How do I reduce the gain on my build ?

[catnine]

 First here is a schem of my build .


 I added a spdt switch to break the 25uf bypass cap on V2 and add in a 112K NFB resister double the value of the 6G2 has . On a stock 6G2 there is no bypass cap and always the 57K NFB . I can switch mine in or out . When I have the NFB out and the bypass cap in at about 4 the amp is clean and sounds good but above 4 say at 5 it begins to break up and the breakup is not pleasent sounding . If I switch out the bypass cap and add in the NFB then I need to crank the vol up to 6 before the breakup accures.

 At 4 no NFB the amp is clean and pretty loud . I looked at the princeton AA964 and it is like a SF champ up to the PI but it seems to keep the 25uf bypass cap in place to bring the gain back  lost by the BF tone stack. And it has a 2.7K NFB resister so it feeds back more NFB .

 I already use a 12ay7 as the preamp tube since using a 12ax7 makes it break up even sooner.

 The only thing I can think of to have the open sound of no NFB is to somehow break the 25uf bypass cap and not add the NFB resister. In order to do that I need another switch since the way I have it now is usefull . I don't know where I can place another on/off switch just to break the NFB .

 I already tried the BF tone stack in this build and it sucked all the character out.

 Any thoughts' that might help?

[PRR]

So play it at "4". What's a number?

[Ed_Chambley]

325-0-325 rectified with 5y3 and you are getting 415?  I assume you are wanting to get more clean headroom.  Reducing bypass cap values are going to lessen bass response which will eventually eliminate any breakup coming from low Hz on the speaker.  If I wanted the most, I would self bias the PI.  Paul C mod.  Decrease the dropping resistors and get more voltage at v1 and the PI.  Maybe even add a choke.  I would also make use of V1b and use a different bypass.  Since you have 2 inputs it will add another tone and can add another volume pot.

I attached a tone stack I use for this purpose.  It is a 5e3 layout, but it is not much different.  I have used various versions of this tonestack and found it to deliver the most clean headroom with the other things I have mentioned.  The final results are a symmetrical breakup/tube saturation.  More of a singing quality as opposed to raw breakup.  It doesn't have that point in volume where it goes from clean to break-up, it is more gradual.  I am also able to "tune" the 2 inputs one for single coils and one for humbuckers, however it is a completely different amp.

[printer2]

The only thing I can think of to have the open sound of no NFB is to somehow break the 25uf bypass cap and not add the NFB resister.

Get a DPDT switch with a center off position. If you want to reduce the gain of the first stage capacitor bypass put it on the other pole. To clean up the distortion, leave the Cathodyne stage and put a 470k grid stopper on the grid. Reduce the 0.02uF capacitor before it to 0.005uF. This should smooth out some of the breakup in the PI.

[catnine]

I built it with larger transformers to get more headroon and bottom end.

 Most of the suggestions aim toward reducing the low end .

 There is no room for a dpdt ,  all I could fit in the spot I had was the same switch fender used for the old ground switch . Although switching out the second gain stage bypass cap does not affect the bottom that I can tell but then the NFB is in play so it's there but just tighter.

 There is no room for another vol pot either.

 Here is a shot of the switch


 this is the inside of the chassis. the only place to add a switch would be the right back but it would be right close to the preamp section tubes.


this is the front of the amp and where I placed the switch, there was already a hole in the chassis where the vol pot would go on a SF champ , in fact when I used the BF tone stack I used a BF Champ faceplate since the music master bass amp and the SF champ use the same chassis, just different cutouts in the bottom and back .
 
This is the back of the amp


 

[catnine]

So play it at "4". What's a number?

That's good advice.

However, if that's not going to do it for you .............................

1) Use a 12AT7 instead of 12AX7

2) Use 4.7uf or 5uf cathode caps

3) You can drop the volume pot down to 500k or parallel a 500k from wiper to ground.

4)  Change the .02 coupling caps to .01 & the .1 to .047 or .033.

With respect, Tubenit

 Are saying change the 12ax7 to an at7 for the V2 second gain stage and PI ?

[catnine]

So basically what I have built is a fixed bias 5E3 with one vol and one tone and 2 inputs since I only use 1 triode of the 12ay7. just a higher voltage version with fixed bias . Is that correct?

 I left the dropper values of the 5E3 because the 6V6's plates with these trannys would have been to high . At first I had the one vol and one tone wired like a 5E3 but it went into breakup far sooner so there is some difference it the later 6G2 tone stack as far as the way it is wired because that changed quite a bit. My PT has a much higher mA rating than the 6G2 which is 70mA and mine is 150 mA. The OT is twice the size of a stock BF deluxe .

 My voltages are similar to the AA964 princeton yet it has the same PT as the SF Champ with 325-0-325 @70 mA so they used a GZ-35 rect one extra filter cap yet a 1K dropper before the screens I don't get the 18K dropper between the two 20 uf caps because it is tied to nothing so it must just act as another filter stage to another 18K dropper so that's 36K before the PI and preamps tubes @ 290VDC before the plate load resisters. I have the 5k and then a 22K and still have 312VDC before the plate load resisters.

 I suppose I could use the two inputs and have one to each triode of the V1 12ay7 . I used to use the #2 input to cut down the input a bit . But if I did use the two triodes I would need to use 33K ohm to each grid of V1 and then add another 1.5K bias resister with no bypass cap , I wouldn't have a high low input any longer. I guess I could leave the 1 meg on the inputs to ground as they are now , at least I think so , it has to be there I know that. But to do this I would need another vol pot , I can't just jumper pin 1 to pin 6, I have to think about that one. There is no room to use a stacked pot or it will hit the eyelet board. The dual gang pots are on one shaft so if one did fit wouldn't the grid signal be shorted through the 1 meg on the input jack I was not using?

 The other thing I could do is not dig in so hard when I play but that's a hard habit to break. I also use heavy strings 13 to 59 .

[catnine]

Are saying change the 12ax7 to an at7 for the V2 second gain stage and PI ?

Sure, 12AT7 is 70% the gain of a 12AX7.

So, if it were mine ...................... with your goal of less gain ................. I change that tube and the 25uf cathode caps to 4.7uf.

With respect, Tubenit

 What about the bias of the 12at7 can I leave it like it is with the 12ax7 ? If so maybe I'll try the 12at7 first and then go frome there , the 12at7 may just be just enough to reach the goal I'm after. These days I sort of like doing one thing at a time to see what it does and a tube is not a big deal and I have a 12at7 .

[HotBluePlates]

HBP has left the building.

[catnine]

Why not lose the input stage bypass cap altogether? That creates local negative feedback and reduces the gain of that stage to about half.

You could just unsolder one leg of that cap and play the amp to see if it moves in the direction you want. You'll have the answer quickly.

 I could except that I just replaced that cap and the reason I did is because the resister would not reach across the eyelets on the weber 5E3 board I used and I had the on 1.5K break loose at the second gain causing noise and once I fixed that the one on the preamp broke loose because I just soldered them against the caps leads thinking they would hold but they didn't so this time I twisted each end of the resisters around the caps leads which reach easy and soldered them to the caps leads and then bent the new caps leads down so they would stay put in the eyelets. . So while I was in there last week I replaced both bypass  caps and resisters the same way . I didn't want any more broken joints .

 I was getting all sorts of noise when I turned the vol pot up or down and found the broken solder joint just by checking the voltage on the preamp bias the probe touched it and it was obvious where the noise came from. All I can do now is add a bit of lead to another 1/5K bias resister and remove the new cap with the resister I have in there now.

 I suppose it's worth a shot . I was told on another forum that I would need a scope to see what stage was overdriving at what point. I see that same 1.5K and 25 uf cap on just about every fender amp whether it uses a 12ay7 or a 12ax7.is that just standard fender style?
  You saw my schematic would you say I basically have a high voltage version of a 5E3 with fixed bias with larger tranny's? I'm near the point that I'm close to wiring it like a BF tone stack and a LTP like a BF Deluxe. Maybe it's the split load I don't like. I never played a brown princeton or a 5E3 all I know is BF fenders when more for clean and headroom . Of course I wouldn't know what values to use for a LTP and if I did know I may find out that it was all the wrong thing to do. Man I'm lost.

[Ed_Chambley]

Here is a layout that will increase headroom a lot.  You can start at the front and check as you go.  The only other thing is to self bias the PI.  Easy to do.  You can put dual pots in, but it will be tight.  It is difficult using a fender chassis, but I have used dual PEC pots in the same type of chassis, but I have to cut the chassis, with alpha dual it is not necessary.  When installed they are not as long as the input jacks.  May have to remove all the jacks and pots where you can lift up the board.

You will not lose bass by changing the 25uf to 4.7.  Actually you will gain a more focused bass.

You can ignore the tonestack and the trick switch.  Tubenit's James stack will work very well.   Also, you will be able to use a 12AX7 in the PI and it still will have lots of headroom.  I found I have more than using an 12AT7. A 5751 is also a viable option for the PI.  I tried them all and found I get the most headroom with the 12Ax7 is using the board values, but it is so easy to audition different tubes.

[Willabe]

Man I'm lost.

       
The guys offering advice aren't lost & you've been given some very easy simple things to try.
I mean this respectfully ...................
I'm guessing you're over thinking this project.  

Yep.

The suggestions you've been given:  1) lift one end of the cathode cap   or 2) replace the 25uf caps with 4.7uf   and replace the 12AX7 with a 12AT7  are very very simple and quick mods to try out.   Really straight forward stuff to try that will only take a few minutes to do.  

Those suggestions are MUCH easier than rewiring the amp to an LTPI which probably won't accomplish your goal.

Double Yep. Just try them, 1 at a time.


          Brad    

[Ed_Chambley]

Man I'm lost.

       
The guys offering advice aren't lost & you've been given some very easy simple things to try.
I mean this respectfully ...................
I'm guessing you're over thinking this project.  

Yep.

The suggestions you've been given:  1) lift one end of the cathode cap   or 2) replace the 25uf caps with 4.7uf   and replace the 12AX7 with a 12AT7  are very very simple and quick mods to try out.   Really straight forward stuff to try that will only take a few minutes to do.  

Those suggestions are MUCH easier than rewiring the amp to an LTPI which probably won't accomplish your goal.

Double Yep. Just try them, 1 at a time.


          Brad    

I hear you brother tubeman.
Take the quote from Nike-Just Do It!
BTW Brad, I know the layout of the tweedy deluxe works quite well and even better when you split the cathode in V1.  I don't really care for the tonestack, but it's not bad if you are looking to play blues.

Then again, I am guilty of over-thinking sometimes.  I know where Catnine is coming from.  Trying to understand, but sometimes you just gotta melt some solder and change some tubes to understand.  I forget that I don't have to know how oranges are grown to eat one.

[catnine]

Ok . Right now I don't have any 4.7 uf caps . Ed I think suggested the Paul C mod , I have heard of it but don't know what it does.

 I only have a vol and tone pot and in order to add another pot I lose the spdt switch I have now which takes out the 25uf bypass cap on the gain stage before the PI and ands in NFB and that does change things a lot. So to make a stack with a vol treb and bass I would need to take off the BF music master face plate and install the BF champ faceplate like I did once before. I could lose the low input jack and place the switch there. I do like that feature .

 I am confused about the bypass cap in the respect that in my head and from what I've read a smaller bypass cap does not allow the low freqencies to pass and a 25 uf passes all guitar freqencies or lets say add's gain to all freqencies. I know this because it did this on my SF Champ build . That brings me to this point of thought. What affects the bass response through the speaker the most , the bypass caps or the size of the OT?

 I you guys are all trying to help and I do appreciate that really. Yes I am overthinking this , problem is once I do a change like lifting the 25uf bypass cap in V1 preamp by the time this is done I like to be able to switch it in and out to compare it and if I like both then leave the switch there. There are some things you can't make switchable.

 Printer2 suggested placing a 470K grid stopper on the grid of the PI and lowering the coupling cap to a smaller value, I don't what this does , should I check the voltage of the PI grid and if so what should it be at idle?

 I am going to start with playing the amp again. Then since it's simple try the 12at7 . Then go  with the preamp bypass lift with a temp switch. One thing I don't want is drilling holes to add switches unless I decide I like certain changes that can be switchable. If none do the trick then I may just install the BF tone stack and change the build to a SF princeton no trem since it is a SF champ all the way to the PI and from there it's a 6V6 fixed bias P-P amp . Then I can play with the tone stack if needed.

[Ed_Chambley]

Ok . Right now I don't have any 4.7 uf caps . Ed I think suggested the Paul C mod , I have heard of it but don't know what it does.

It self biases the PI.

 I only have a vol and tone pot and in order to add another pot I lose the spdt switch I have now which takes out the 25uf bypass cap on the gain stage before the PI and ands in NFB and that does change things a lot. So to make a stack with a vol treb and bass I would need to take off the BF music master face plate and install the BF champ faceplate like I did once before. I could lose the low input jack and place the switch there. I do like that feature .

However you want to do it.  I use dual pots.

 I am confused about the bypass cap in the respect that in my head and from what I've read a smaller bypass cap does not allow the low freqencies to pass and a 25 uf passes all guitar freqencies or lets say add's gain to all freqencies. I know this because it did this on my SF Champ build . That brings me to this point of thought. What affects the bass response through the speaker the most , the bypass caps or the size of the OT?

Both really.  Amps were not just made to amplify Guitar.  With guitar you do not need to pass frequencies as low as a bass guitar.

 I you guys are all trying to help and I do appreciate that really. Yes I am overthinking this , problem is once I do a change like lifting the 25uf bypass cap in V1 preamp by the time this is done I like to be able to switch it in and out to compare it and if I like both then leave the switch there. There are some things you can't make switchable.

 Printer2 suggested placing a 470K grid stopper on the grid of the PI and lowering the coupling cap to a smaller value, I don't what this does , should I check the voltage of the PI grid and if so what should it be at idle?

 I am going to start with playing the amp again. Then since it's simple try the 12at7 . Then go  with the preamp bypass lift with a temp switch. One thing I don't want is drilling holes to add switches unless I decide I like certain changes that can be switchable. If none do the trick then I may just install the BF tone stack and change the build to a SF princeton no trem since it is a SF champ all the way to the PI and from there it's a 6V6 fixed bias P-P amp . Then I can play with the tone stack if needed.

[Ed_Chambley]

HBP was kind enough to explain to me and give me a formula to determine what frequencies will be amplified with a combination of a cap and resistor.  It finally sunk in that cap and resistors when used as cathode bypass is not a "brick wall" meaning it is not going to block anything really, it is just amplifying what you do want.  You are focused on your OT which seems to be a nice one.  Now you have it, but you are attempting to tweak your amp.  Your OT will send to your speaker what your circuit dictates.

The formula is 1/(2*pi*Resistance*Capacitance).  http://www.vaughns-1-pagers.com/music/musical-note-frequencies.htm
This will show you the notes on guitar and piano and their respective hertz.

First try the simple things that have been suggested as you do not have any caps to play with.  It will give you something to try until your cap order arrives.  You are placing an order for some caps, right?  Don't get hung up on the 4.7 as it is just one value.  I mentioned going to mouser.com and order some 1.1, 2.2, 3.3, 4.7, and something in the 7 or 8 and 10uf.  I get 50v.  They are cheap.

Forget the Paul C. mod for now.  It is just a common mod for princetons.  I tried it in a 5e3 as well.  It does help if you are looking for clean, but do it later as you may not want to.  It deals with the PI and this is not where I begin tweaking.

Anyway, HBP told me to not try to restrict later in the circuit, but to amplify the Hz I want.  You don't even have to use the formula, but if you do you will understand more and it will reduce tweaking time on future builds.

Guitar open e is 82.407Hz.  Lowering the cap on v1 will get you closer to this and at the same time reduce how much you are amplifying lower Hz, not removing them.  Remember, it is not a brick wall.

Just try an experiment.  After trying tube changes and lifting the cathode you are not happy with what you get then use the layout I posted.  Starting at v1 change.  Check it and see if you like it better if only slightly.  Moving left try another.  Each change will remove a little more speaker flap and give you the ability to raise the volume with less breakup.

The way I understand it is it takes more wattage to reproduce lower Hz cleanly.  That is why bass amps traditionally have lots of wattage.  Amplifying lower frequencies than your guitar is capable of producing is a waste and often not very good sounding with guitar.

Continue this process until you reach the tone you want.  If you make a change and do not like it you can either change it back or try something in-between.  What I am saying is it is not written in stone, but I can tell you I have a 5e3 built this way with no trick switch.  My OT 6k6.  I have 2 different channels.  The one I use for my telecaster is cap 4.7uf/820 ohms on v1a and les paul humbucker 3.3uf/680 ohms.  Has lots of headroom, but someone who likes the tone of a stock deluxe would not like it.  Works very nicely, but if you plug in an electric piano it does not sound very good in the first octave.  It will play the notes just fine, but it is sort of thin.

It is actually possible to put on a "better OT" and you amp sounds worse because it is reproducing a frequency from your circuit better, but it is not a frequency you want.

[catnine]

I haven't done anything yet. I just played through it again today. I had it on 4 without the NFB and then raised it to 5 and then I got some breakup on chords only but if I bring in a bit more treb using the tone pot the breakup seemed smoother . Once I dialed it to 5 the breakup was not that bad as long as I keep the tone pot near 7 . By that point my wife came in asking me to turn it down because I was drowning out the TV . I had the bedroom door shut and the hallway door shut .

 I kept it on 3 and she said that was fine.

 I tried it with the bypass cap switched out and the NFB in and brought up the vol just to get it as loud as on 3 and if I bring up the treb to 8 the bass is there but just tighter and when I bring up the vol I hit 7 before any breakup comes in and the more treble opens it up so it does not sound so choked off .

 It's more touch sensitive without the NFB and the bypass cap in play . The amp is quieter when the NFB is in play. Being 5 feet away without the NFB I could hear the typical strat hum buzz but then the fish tank filter was on so it may affect this some . I don't hear that in the living room since there is nothing on in there. It's like when you have a florescent lamp on near the amp.

 It does not take much turning the vol pot to bring up the vol  a lot . Just one number up and it's real noticable , it may be the 1 meg vol pot but most fenders use that value that I have seen . I did change the first coupling cap long ago from .1 uf to .02 to get rid of some bottom end because at the time I had a 30 watt HD weber silver bell ceramic 12 with a 40 oz mag and 1 3/4" in the amp and I could not get the tone pot to tame the bottom end, no treble at all When I changed that to a lighter sig 12S alnico the tone pot then had a real difference.

 I don't know now perhaps PRR is right. just play it at 4 . I usually never use the strats tone pots but if the tone is a bit bright I can dial it back and that changes things as well but in a different way than the amp tone pot does. I only use the neck PU or neck and middle sometimes the middle never the bridge.  By the way how do I get the post space box where I don't run out of room?

[Willabe]

Trying to understand, but sometimes you just gotta melt some solder and change some tubes to understand.  I forget that I don't have to know how oranges are grown to eat one.

Triple Yep.

And mmmm oranges!  


            Brad    

[catnine]

Thanks Ed;
 
 I see you use a different cap value with a different bias resister value doesn't this affect the tubes cathode bias seting. I also se you have a 15 volt 5 watt zener diode on the HT center tap , what is that for?

 I'll tell you . what I am confused by is why fender on most all of the amps use the same 1.5K bias resister and the same 25uf cap . I know other builders use different values for different reasons yet I did follow what fender did just so it would sound like a fender and not a marshall .

 Before my 77 fender MM bass amp died the first thing i did was replace the OT with the one I use now and right away I got a lot more lows and that's basically what I was looking for . but the PT was leaking some black tar like stuff when I got it and it went out and took the tranny that they used as a phase inverter with it . Then I got the Allen Amps PT to go with the OT I got from him since he used them in many of him builds as a set and recommended them . The 5E3 seemed to be simple and easy to build and was close and not knowing that's what I began with .

[tubeswell]

what I am confused by is why fender on most all of the amps use the same 1.5K bias resister and the same 25uf cap .

in a typical 12AX7 stage the 1k5/25uF combination bypasses all the frequencies you're likely to get from a geetar (boosting the full spectrum). In v1 this isn't actually a bad thing - provided that you can manage to keep the excess bass out of the signal path in other ways, because having maximum gain in V1 helps with a better signal:noise ratio overall.  Having said that, knocking the bypass cap size down enough often does help clear up the signal. try experimenting with lowering the Ck values to 1uF or less, or try dropping the Ck altogether from various stages.

[HotBluePlates]

HBP has left the building.

[catnine]

I'm near the point that I'm close to wiring it like a BF tone stack and a LTP like a BF Deluxe. Maybe it's the split load I don't like.

The cleanest guitar amp I've ever heard uses a split-load inverter. My McIntosh MC-30's (tube hi-fi power amps) use a split-load inverter (though the signal is later boosted with a differential amp). The Hiwatt DR504 I used to have, which can be brutally loud and clean (unless you really want dirt) uses a split-load inverter.

I'm thinking you just want conversation. Otherwise, you'd have saved yourself 23hrs 55min and removed that bypass cap, found your amp's signal level goes down some and that it stays cleaner to a higher setting on the volume knob. I also think that, like the rest of us, what trips your trigger one day doesn't strike you the same way next so you look for something more, better.

 No HBP, it's not conversation just advice so I understand . Yes on the second part " what trips my trigger one day doesn't strike you the same way the next so I look for something more , better". So true , when I had ten amps I had a choice and some days one did not sound quite the same so I used another. I wouldn't toss up topics and take up peoples time just for the sake of conversation. I read all of this stuff and try to understand and these days most of it just blows right past me. I have done a lot of searches like tube amps preamp bias /resister and come up with forums with all sorts of diiferent opinions/info or lord valve and read through it but get lost because I don't understand the terms used.

[Ed_Chambley]

 I see you use a different cap value with a different bias resister value doesn't this affect the tubes cathode bias seting. I also se you have a 15 volt 5 watt zener diode on the HT center tap , what is that for?

To drop voltage.  I did not use a zener and never have.  I posted the layout because the board values make for a 5e3 with the most headroom I have ever heard from a 5E3.

 I'll tell you . what I am confused by is why fender on most all of the amps use the same 1.5K bias resister and the same 25uf cap . I know other builders use different values for different reasons yet I did follow what fender did just so it would sound like a fender and not a marshall .

[/quote]
I seriously doubt any old Fender amp would actually be 25uf/1k5 if tested.  I have a very nice sounding 73 Super Reverb that has been modded through the years.  A friend wanted to copy it, so I loaned it to him so he could change the values to match mine.  It still doesn't sound the same, but why would it?  He doesn't have the same speaker arrangement, but if you plug his amp into my cabinet, it still doesn't sound the same.

Here is a couple of questions for you.  Jerry Reed used a Les Paul to record Amos Moses and Jimmy Page toured with Led Zepplin using a Les Paul.  Which one sounds like a Les Paul?  Ted Nugent recorded Stranglehold with a Fender and Keith Urban frequently uses a Marshall 1987 to record.  Which one sounds like a Fender and does a 5E3 Deluxe sound like a Fender or does a AB763 Blackface Deluxe sound like a Fender?  What is "the Fender sound"?  If you had a twin with upgraded JBL's, does it sound like a Fender or would it be better to have CTS or UTAH's speakers?

[catnine]

I seriously doubt any old Fender amp would actually be 25uf/1k5 if tested.  I have a very nice sounding 73 Super Reverb that has been modded through the years.  A friend wanted to copy it, so I loaned it to him so he could change the values to match mine.  It still doesn't sound the same, but why would it?  He doesn't have the same speaker arrangement, but if you plug his amp into my cabinet, it still doesn't sound the same.

Here is a couple of questions for you.  Jerry Reed used a Les Paul to record Amos Moses and Jimmy Page toured with Led Zepplin using a Les Paul.  Which one sounds like a Les Paul?  Ted Nugent recorded Stranglehold with a Fender and Keith Urban frequently uses a Marshall 1987 to record.  Which one sounds like a Fender and does a 5E3 Deluxe sound like a Fender or does a AB763 Blackface Deluxe sound like a Fender?  What is "the Fender sound"?  If you had a twin with upgraded JBL's, does it sound like a Fender or would it be better to have CTS or UTAH's speakers?

 Well since they both used Les Pauls it would depend on what amps they used and their playing style. All fenders have a different sound so each one sounds like a fender in it's own right and it depends again on the player and the guitar used . If you wanted a stock twin depending on the type of  twin since there were a few through the years but if it were a SF twin and you wanted it to sound close to original you would get speakers as close to the original , if you  wanted something different you would go with the JBL's . Then again I can't tell you what speakers were offered in a SF twin. If it were SRV's super reverb then it would not sound like an out of the box SR. If any amp is modded it's going to sound different but if it were a new 69 twin it's going to sound very close to any new 69 twin. I do get the point. Ted Nugent 

[catnine]

Today I spent hours reading through Valve Wizards site all about preamp tubes and bypass caps and internal tube resistance so I have a better idea of how they work . Also read about cathodyne PI's and he stated this "This is the real 'secret' to obtaining a smooth, consistent sound from the cathodyne, no matter what kind it is. If you are using a cathodyne always give it a nice big grid-stopper. The tonal reward is startling!!! Yes I know Leo Fender didn't use any, but he wasn't designing amps to be overdriven, and this is the 21st century."

 I don't see any harm in trying that ,it's easy enough.

 So I am going to add another switch so I can take the 25uf bypass cap in and out of the preamp section. and try the 100K on the grid of the PI , can't say if fender ever had this problem but then mine is not a fender in the true sense. I'll just see how that goes then go from there if I need to.
 Spoke to David Allen today he said this about the OT I have " The core of an OT eventually saturates so no more power can pass through it.  The larger core of the TO25 compared to a typical Deluxe size OT allow it to pass around 30W before saturation.  The bass is the first to distort so a larger OT appears to allow more clean bass.  The TO25 is on the large side for 6V6s but on the small side for 6L6s.  It need a 2 ohm or a 4 ohm load with 6L6s."  I asked about the split load PI and he said they have a raspy ratty OD sound to him. I can't define mine sounding like that.

[Ed_Chambley]

 Well since they both used Les Pauls it would depend on what amps they used and their playing style. All fenders have a different sound so each one sounds like a fender in it's own right and it depends again on the player and the guitar used . If you wanted a stock twin depending on the type of  twin since there were a few through the years but if it were a SF twin and you wanted it to sound close to original you would get speakers as close to the original , if you  wanted something different you would go with the JBL's . Then again I can't tell you what speakers were offered in a SF twin. If it were SRV's super reverb then it would not sound like an out of the box SR. If any amp is modded it's going to sound different but if it were a new 69 twin it's going to sound very close to any new 69 twin. I do get the point. Ted Nugent 
[/quote]
I am sorry if you considered my questions off topic.  I actually was attempting to bring the discussion back on topic.  Using the term gain, I assumed you were wanting to get more clean volume before breakup.  Gain is commonly referred to as distortion I guess because if an amp has a gain knob it usually adds distortion.

In reading your comments you stated you did not want to change things and end up with a Marshall which I understood to mean distortion because most people refer to Marshall amps as having distortion.  The older Marshall's have beautiful clean tones and we all know the first Marshall was a Bassman.

I got sort of conflicted because I thought you did not want to mod your amp which I did not understand because the amp has been modded as soon as you used a different OT.

The point I was making was to try some of the suggestions you have been given and let us know how your amp responded.  These suggestions were/are simple and quick to do and to change back if you do not like them.  This is a forum and a lot of us read others topics to learn and understand.  I guess your approach is different as it seems as if you want to know what the modifications sound like before you do any.

My questions were simply examples of different modifications players make to achieve the tone they want.  The reason for the Les Paul comment was the guitar has to be considered as well.  Moving forward, I now understand how you approach your amp tweaking and will keep my comments on topic and try to keep in mind Gain=Distortion even though sometimes people refer to distortion and speaker flap being the same thing.

I will just read and wait and see how you tweak your amp.  Also, I did want to mention when I was looking to buy a Egnater Tweaker 15 watt amp, I tried out a lot of different ones with the same specs and they did sound different from one to the other.  In some cases, much different.  All the same amp, but maybe in 69 when Fenders were hand built the tone was probably a lot closer from amp to amp.

Sorry for rambling and if I got off topic again.

[catnine]

Ed
 
 I only meant Ted Nugent was off topic not the suggestions you and other offered . Just don't like Ted Nugent , he played in a band called the Amboy Dukes that happened to play in on of the same clubs the band I was in played at in Illinois. That's all I don't want to go into details on him . It was not a personal attack on you or anyone else , I appreciate everyones input . If you read my post again I specifically wrote Ted Nugent and after that put the off topic thing.

 As far as my amp goes it began with those transformers right after I put the OT in the music master bass amp then the PT burned out so I got the PT Allen amps used with the same OT I got since he used this pair in similar builds the TP25 and TO25 . I used them because they fit right in the MM bass amp chassis without any cutting yet I never considered the voltage would be higher and they would work with both 6V6's and 6L6's .

 I didn't know , it was my very first attempt top build my own amp other than a kit I got before to build a 5F2A but that was a kit all designed to mimic a 5F2A using a Hammond chassis and trannies . I gutted the MM chassis and looked at different simple fender circuits to find one that ran 6V6's and used a 5Y3 and it seemed that the 5E3 was simple was similar to many power sections using 6V6's and a split load which was again simple to build and I wanted to use the one vol and one tone setup since that is  what the faceplate and chassis on the MM bass amp had , I didn't want to butcher the face plate and at that point the 6G2 tone stack seemed like the perfect simple fit minus the trem which I never use and would require two more pots = butchering the faceplate. I was happy with the MM bass amp once the PT went for whatever reason I just went with what seemed close enough. So here I am now. The amp sounds fine yet I feel it could be better all I am trying to do is figure out the simple way to get to sound better with less gain. I have to work with what I have since I can't afford more trannies . I have been studying other fender schems of similar design and voltages at each point to see if there is a way to perhaps change the voltage on the preamp section and PI and second gain since they seem higher in later princetons mostly in the preamp. I know the higher voltage I have is the result of the PT and larger OT because I later built 6G2's with replacement PT and OT from weber that were in line with the 6G2 and they sounded much different. I used the 1k and 10K droppers on them yet I don't want to lower the voltages I have now I   don't want to use zeners to waste voltage I want to find a way to work with them.

[catnine]

Is it worth adding a 100K grid stopper on the grid of the PI to pin 7 > Valve Wizard seems to think so. ? I posted that a few posts back .

 Also the voltages are close to a SF princeton yet the preamp on my build has 153 on the plate of the 12ay7 and the sf princeton has 190 with a 12ax7 so I though if I raised that it may offer more headroom , I know thw 12ay7 draws more mA so before I do that I will plug in a 12ax7 and see what it reads on the plate.

 I am not like most of you, I don't know the math but came figure it out . Iknow I have to try thing to see the outcome these are just general questions.

[Willabe]

There was recent thread that discussed modifications to a 5e3 by some undergraduate students as a senior project.  These students found a way to 12ax7's in place of the 12ay7s. They cut the gain on a 12ax7 in half

They removed the 2'nd gain stages cathode bypass cap.

Here's the link;

http://www.el34world.com/Forum/index.php?topic=14910.0


             Brad     

[catnine]

I think I saw that a while back . They removed the second gain bypass cap and added NFB and a few other things if I recall.

 I was going to try a few things today but had other things I had to do . I already have a switch that cuts out the second gain bypass cap and add's NFB and it works fine yet it's not quite that same when you stick a 12ax7 in V1 then it just add's back the gain you removed at least most of it.

[catnine]

So far all I did was swap tubes. First I removed the 12ax7 in V2 and installed a 12at7 . At that point the amp didn't sound different all it did was allow me to bring the vol up from 4 1/2 to 6 1/2 before the breakup set in . Then I left the 12at7 in V2 and changed the 12ay7 in V1 to a 12ax7 . It didn't really change the sound much but it changed the point of breakup to about 5 1/2 on the vol pot. It seems the 12at7 makes the most difference overall. There was a subtle change in tone in the bass yet it was really difficult to tell. The treb seemed to a bit more pronounced with the 12ax7 in V1 and the bass was a bit more focused. Yet with a bit of a turn on the tone pot I could bring it back to pretty much the same as with the 12ay7 in V1.
 
 If I switched out the second gain bypass cap and added the NFB loop the gain is less no matter if i use a 12ax7 or 12at7 in V2 yet if I raise the vol level 2 numbers up the vol level is about the same with the bypass cap and no NFB , however the bass nots are tighter and the breakup is smoother but if I use a 12ax7 in V1 then the breakup seems to hit that raspy sound, this was not the case if I had the NFB off and V2's bypass cap in. So I can see how the preamp affects the second gain and how the second gain affects the preamp. 

 I did notice that with the 12at7 in V2 the breakup was not quite so raspy as with the 12ax7, it was more smooth this was either with the 12ax7 or 12ay7 in V1. 

 Like I said the 12at7 in V2 seems overall to make the most difference.  I am not sure why the breakup is more raspy with the 12ax7 in V1 with the V2's bypass cap out and the NFB on. It's really difficult to tell it seems to  sound best with the 12ay7 in V1 and 12at7 in V2. Once I get near 7 on the vol the amp is very loud . It's difficult to tell because by the time I change tubes I sort of forget how it sounded before . The main difference is the vol setting which means nothing but the less raspy breakup means a lot. If I just turn the vol pot a tiny bit down on any strat the buzz goes away. I don't get this with my Champ build. It may be the larger OT I can't say. I keep thinking it may be because I have the switch that switches out the V2 bypass cap and add;s the NFB is right next to the input jacks so I have a output lead right next to the inputs.

 Another thing I did notice even before the tube change is with any one of my 3 strats if I stand next to the amp it seemed quiet , I used a long cord from the guitar to the amp and seemed like the further away I moved this buzz I get was worse but if I put the strat behind the wall it was gone so it must be typical strat buzz, none of my strats have shielded cavities.

[Ed_Chambley]

I assume you have some caps 25uf or smaller.  They do not have to be electrolytic.

Just for a test, put one across the first 25uf going to the cathode of v1 and another across the other 25uf.  They look like sprague elitics.  You do not have to solder them in, just use alligator clips.  If you do not have clips, just twist them around the leads on both sides paralleling the caps you have there making sure you have contact.

Keep the 12Ay7 in v1 and a 12Ax7 in v2.  Play it and see if you like it better.  You will not have to remember what it sounded like before.

Let us know what happens.

[catnine]

I assume you have some caps 25uf or smaller.  They do not have to be electrolytic.

Just for a test, put one across the first 25uf going to the cathode of v1 and another across the other 25uf.  They look like sprague elitics.  You do not have to solder them in, just use alligator clips.  If you do not have clips, just twist them around the leads on both sides paralleling the caps you have there making sure you have contact.

Keep the 12Ay7 in v1 and a 12Ax7 in v2.  Play it and see if you like it better.  You will not have to remember what it sounded like before.

Let us know what happens.

 If I put the caps across the existing 25 uf won't that make it in parallel and make the 25uf higher ?

 Also if you would look at post #5 . I have a switch to switch out the 25uf cap on V2 and add NFB but looking at it I have the NFB (output) right next to the input jacks to the right , the switch is seen just the back and you can see the green lead on the left , that is the NFB lead form the output jacks that could be causing problems can't it . also you can see how I moved the +side of the bypass cap to the switch . I think that is not a good idea .

 Also since a 12at7 draws more current than a 12ax7 dosen't that alter the bias placing a 12at7 in a circuit biased for a 12ax7?

[Davidg]

Dude! I do not mean to offend but u have been going on with this for almost a week and have been offered numerous suggestions and have yet to touch a soldering iron.Ed has even given u a suggestion u dont even have to solder and u are still on the computer working out theory.

Go try something! Even if its wrong, you can easily reverse it and try something else.Bottom line is no one knows what this or that tweak will do to your amp exactly because what is on paper doesnt always jive with what sounds good and all we have to go on is your description of what your amp sounds like from your perspective.If the theory is always right why did fender have to abandon the bias balance circuit? On paper and "In Theory" it was a great idea and all the math worked but in the amp it sounded like KAKA! I really understand where u are coming from as I was much like you once and still catch myself overthinking things but the best thing to do is grab an iron and melt some lead.

I have learned far more with an amp and iron and a DMM in front of me than I ever have from the internet or Merlin or TUT etc.. (Norman Crowhurst being the only exception)

I am sorry if this seems offensive but I promise u will learn more by trying each suggestion one at a time and listening and then go back over why it sounded different in theory than mapping out the theory beforehand to see if the idea or mod suits you.There are way too many variables and things going on in any circuit too know what every little part change will sound like-sound being subjective to everyone anyway.

Again I apologize if I offended you but I feel it is in your best interest to hear this and think about it.

[catnine]

Davidg:

  .I know what you are saying and read all the possible solutions others here have offered.

 Don't think  haven't tried some of them , I have . I also realize there are others here asking questions that is what a forum is for .

 I also realize that no one other than me can hear the results or find the sound I am looking for. I am not stupid and I am not implying you said I was.

 Right now as far as I am concerned the amp sounds better than it did and I will find a way to get it where it needs to be , after all I did build it.

 Don't you think I already thought about all of this before I posted anything, if not then you would be wrong.

 I will tell you what I take offense to is you coming on here out of the blue telling me what I already know as if I'm a child who put absolutely no thought into anything before asking a question . The fact is no one is forced to answer and I do appriciate all the people here who have taken the time to do so. Fact is I already have the amp opened up and even before I made the post I had it open and looked everything over to go over everything I could to see if there was a way to go and I looked up everything I could find and read all I could find before even posting this in the first place. It may have been a week here but it's been a month since I began looking through the amp before I asked anything so I could be as specific as possible.

 Question is , why does it bug you so much to feel the need to jump in and voice your thoughts especially when you have no idea what I am doing or have done well before I posted this . I have seen  posts not so very long ago from some asking questions very similar to mine that are now offering me advise, not that it does not make their advise valid. I have worked and reworked this amp a few times since 2005 when I first built it. I thought perhaps someone here may have run into the same thing I have and it's as simple as that.
 
 Bottom line . I didn't build this amp out of the blue and have melted plenty of solder. Yes perhaps I am over thinking this entire thing and this has already been pointed out to me a few times, but lets be honest here and tell me you still don't overthink every single build you have done that didn't turn out just like you hoped it would especially when it's a copy of a build with some minor changes. What's offensive is passive aggressive, if the posts bother you just come right out and say it . I already know everything you have stated, this is not my first time around the block telling me what's in my best interest.

[Ed_Chambley]

I assume you have some caps 25uf or smaller.  They do not have to be electrolytic.

Just for a test, put one across the first 25uf going to the cathode of v1 and another across the other 25uf.  They look like sprague elitics.  You do not have to solder them in, just use alligator clips.  If you do not have clips, just twist them around the leads on both sides paralleling the caps you have there making sure you have contact.

Keep the 12Ay7 in v1 and a 12Ax7 in v2.  Play it and see if you like it better.  You will not have to remember what it sounded like before.

Let us know what happens.

 If I put the caps across the existing 25 uf won't that make it in parallel and make the 25uf higher ?

Yes, you understand parallel capacitance, but I was hoping you would do it and maybe, just maybe you would try series as well while you were there.  You see, I do not think "Gain" and reducing it is going to get the amp to respond in the way you want.  Instead of attempting it, you have moved your discussion off topic and begun discussing current.

Go and get a Boss GE-7.  It will fix the problem.

[Ed_Chambley]

I have seen  posts not so very long ago from some asking questions very similar to mine that are now offering me advise, not that it does not make their advise valid.
 
Yes perhaps I am over thinking this entire thing and this has already been pointed out to me a few times, but lets be honest here and tell me you still don't overthink every single build you have done that didn't turn out just like you hoped it would especially when it's a copy of a build with some minor changes.

I already know everything you have stated.
[/quote]
If you have seen post from others similar to yours and they did what was suggested, they learned a great deal.  Their comments are not advise or opinion anymore, their comments are experience.  This experience keeps them from having to over think.

For instance, there was a time when I only knew reducing cap values would reduce bass, but I did not know why nor could I have ever known why.  With blind faith based on knowing that there are a lot of members with great knowledge, I simply did what was suggested and got results.  Sometimes what I wanted, and sometimes not.  Not to take away the importance of reading Merlin's stuff, I certainly do not use this information to form an argument as to why it is wrong to do what is suggested.

And yes, lots of people reading these post know what you have tried and what you have not.  You tell us every time when you refer to something you have read elsewhere basically stating The Valve Wizard state.....................(fill in the blank) so what you are suggesting will not work so I am not going to do it.

What type of caps did you order anyway?  If you did not order any, what did paralleling your caps do?  Did they make for less or more headroom?  If it was less and you want more, what happened when you put them in series?  If you get the amp close by trial and error you can them post your findings.  Then someone will explain what the changes are and remove the need to over think.  When you know something, you no longer over think it.

It appears that a lot of the members I have great respect for and who have taught me have left this post.  Like you said, you built it and will get it working the way you want so I really do not even know why I am posting this.  If you really want more clean headroom, jack it up and drive a 5F4 under it.

[catnine]

This is a forum that enjoys helping people that post some problem, concern, or challenge. You've had some remarkably knowledgeable builders list specific things to try.

There is a culture and courtesy on this forum that when someone knowledgeable posts a suggestion,  that the original poster posts a reply regarding their efforts at trying those specific suggestions.

You've been given some very easy & reasonable suggestions to try.

Yet seven days later & 40 posts later, you have done a very very poor job of stating what you have tried regarding those  specific suggestions. 

For example, have you gotten & tried the 4.7uf cathode caps and then reported that?  In fact, there have been numerous other specific suggestions made that you have not reported back on.

However, you have reported that you've read for hrs &  named new concerns and questions ....... many of which also have been answered.

I am wordy and frustrating

Yes perhaps I am over thinking this entire thing and this has already been pointed out to me a few times

I will not try to help you further with this build until you take the responsibility and extend the appropriate courtesy of doing a much more thorough job of posting specific replies of  what you have tried.

With respect, Tubenit

You told me put a 12at7 in V2 which I did and reported the results. I didn't have any smaller caps so I couldn't try those. I see a total of 18 posts by me in this topic and two were a schematic and one were photos of the actual build with the hope someone might see something wrong with the way I placed the switch perhapes oscillation.

 You tell me to put the 12at7 in and Ed tells me not to. So most of it boils down to lowering bypass caps which I don' have so I can't report the results. The other posts to you were asking if the 12at7 will change the bias if set in a 12ax7 biased circuit. Ed told me to reduce bypass cap values as well as you. Ed said to change the tone stack  if all else fails which I expressed there is no room to do so. I said what I can and cant do.

 Some of the post were links from others and one was one member basically telling me to stop asking anything.

[catnine]

I have seen  posts not so very long ago from some asking questions very similar to mine that are now offering me advise, not that it does not make their advise valid.
 
For instance, there was a time when I only knew reducing cap values would reduce bass, but I did not know why nor could I have ever known why.  With blind faith based on knowing that there are a lot of members with great knowledge, I simply did what was suggested and got results.  Sometimes what I wanted, and sometimes not.  Not to take away the importance of reading Merlin's stuff, I certainly do not use this information to form an argument as to why it is wrong to do what is suggested.

And yes, lots of people reading these post know what you have tried and what you have not.  You tell us every time when you refer to something you have read elsewhere basically stating The Valve Wizard state.....................(fill in the blank) so what you are suggesting will not work so I am not going to do it.

What type of caps did you order anyway?  If you did not order any, what did paralleling your caps do?  Did they make for less or more headroom?  If it was less and you want more, what happened when you put them in series?  If you get the amp close by trial and error you can them post your findings.  Then someone will explain what the changes are and remove the need to over think.  When you know something, you no longer over think it.

It appears that a lot of the members I have great respect for and who have taught me have left this post.  Like you said, you built it and will get it working the way you want so I really do not even know why I am posting this.  If you really want more clean headroom, jack it up and drive a 5F4 under it.

 Yes I know many have left this post . Can't say  blame them or you. I already know lower bypass cap values change gain. I felt since it worked quite well for fender all these decades then they had a reason for it, this is not something I cared to argue about. I don't have the funds to go out and buy all sort of caps and parts, yes they may be cheap yet cheap is relative right now in my life and it's personal so I didn't bring it up.

[sluckey]

.
Lamb Chops Song

[Willabe]

Hush Puppy was my favorite.     


            Brad     

[Willabe]

I don't have the funds to go out and buy all sort of caps and parts, yes they may be cheap yet cheap is relative right now in my life and it's personal so I didn't bring it up.

Well you may just have to wait untill things turn around for you and try them then.

There's a lot of people hurting badly in this country right now and who knows when it will get better. Might get a lot worse.

But it's not going to help you or anyone else to keep asking the same things untill your able to try them for yourself.


             Brad     

[Davidg]

Catnine-I think Ed and Tubenit pretty well said what I think and want to say as I said in my post I was not trying to offend or attack and I am sorry if u took it that way.I will  also apologize if I came off as condenscending or preachy or anything similar.Your posts did not bother me  per say but it really seemed that u were disrespectful to people trying to help you although I am sure it was not your intent.I have been in hard spots as well and not that long ago and truly hope whatever your situation is it only improves from here out.I am no guru and would bet there are things that you could teach me about our mutual "obsession" of all things tube so that was not where I was coming from.Now as for your amp do you have something else to pull some caps off of? Know where any old electronics(or maybe even new) are that u could pull some caps from? Old Tv,defunct stereo,radio whatever u can find may have what u need at the moment.I had to do this when I started as I couldnt afford to order many parts and not very often.Get creative and if you like pm me a list of what u would like and your adress and I probably have most or all of it and I will gladly ship all I can and mybe u can help me fix an amp sometime.At the end of the day we are all here to help each other and though we may disagree about some things or have some misunderstandings I think we all just want to learn and have fun and help each other find that sound in our heads we have always wanted to come out of our speakers.

[catnine]

It was never my intent to disrespect anyone on this forum . I really don't see where I did this. So I did some research on my own and added in a bit about what I read on Valve Wizard , well I was told I can ask questions but it would be better if I got some books and learned myself then come back and ask ,so I did research and found some info and asked if the info I found might apply to what I was trying to do. Don't others do this or is it just me?

 I read every single suggestion offered and printed them out and marked them beginning with the simple ones to the more involved ones.

 I have got what I would consider some smart a$$ remarkes but I don't take them personal .
 I looked at all my posts on this topic that I started and I don't see me asking more and more of the same question , I only asked if the poster would confirm something that was not quite clear to me before I dug in and found out I missread it. Like asking if putting a 12at7 in place of a 12ax7 was going to change the bias of the tube , thought if it did it may take me in the wrong direction. It was not to inply they didn't know what they were talking about  and I did all I could to find out before I asked them to confirm.

 Sitting in front of a computer is not quite the same as talking one on one . I don't know anyone here , never met anyone. I got try this tube and then someone else said keep the 12ax7 and do this or maybe the OT I got is making the amp go in the wrong direction. Try the Paul C mod , then don't try it maybe later. Or larger value coupling caps or bypass caps don't lose bottom end they muddy it. Well the bass is not muddy , it's far from muddy .

 So reading all of this offered and I know how my amps does sound I tried to sort through all of it and find what seemed consistent enough that just might offer the change I was looking for. I was first told to just play it on 4 since that's when what I consider raspy breakup to come in just after 4 on the vol so I accepted that and even said so i on reply. I don't even have that many posts on this forum . I asked about transformers and how they affect the sound and bypass caps . I figured if I posted a schematic with all the voltages and a few photo's that might help yet I get the impression no one looked at them and I spent hours on paint to combine the two fender circuits I spliced and then screwed around for more hours to fight with a mouse trying to hand write the voltages in paint. Sure I can see how many views there are of the schem and photo's yet who knows who looked at them. I took the time to look at and study the schems offered to help me and asked questions of the ones that offered them up.
 I didn't like Ted Nugent and I cleared that up but never got any response to that since the poster got offended thinking I was refering to him , well I am not that way , I don;t go out of my way to offend anyone. In one post I said I'm sorry I  won't ask any thing any more and was told I should not feel that way.

 I honestly don't know what to think of all of this. That is why I said I'll figure it out since I'm the one who built the amp then this was taken as an insult with smart remarks. I can tell you this much , if I offered help and someone didn't take it so what , so what , I'm not going to take it personal or as an insult  and then express that on top of it all. what's the point , what do I gain? It helps no one .

 So Ed and Tubenit and anyone else who feels offended I'm sorry it was not what I wanted to do and if you feel it is then I can't help that . If anyone thinks I would actually ask for help then came back on the defense then you are dead wrong.

 I had SF Champs and know what they sound like so I could compare the homebrew I built to that and get it there. I never had a 5E3 or 6G2 I just picked a very simple amp and went from there and it eneded up a lot closer to what I wanted in sound and tone . it's just the sound of the breakup I don't like and for all I know when I placed the NFB switch right next to the inputs that may be all that's wrong and output next to an input so I am going to change that and move the switch so it is not right next to the input jacks and then find a way to plug the 1/2 hole in the BF faceplate , perhaps a dummy input jack with a input jack insulation washer as long as it looks ok and if not I have the original SF faceplate that come with the 77 music master bass amp chassis with no hole there and I;ll put that back on . I like the BF look better but the SF has it's own look and I can certaily live with either. If the breakup still sucks then I have a BF Champ faceplate and I'll go with a BF tone stack and go from there. I am just talking out loud here , I am not asking for advise.

[HotBluePlates]

HBP has left the building.

[catnine]

Yes HBP . That is why a while back I asked about the definition of gain and OD and headroom . Headroom I know about. Then I wondered about the affect OT's had . I suppose I did shortchange myself not using the proper terms .

 I assumed which one should never do it was gain causing the gritty breakup sound.

 I was trying to get an idea asking about gain and OT's before I posted this post but I failed.

 I thought since the circuit was simple and not something like a super reverb I could start out with the 5E3 and then tweek it and some of this did get me closer to what I wanted . The 6G2 tone stack helped as did the fixed bias .

 I never really cranked this amp past 3 because it was plenty loud at that point and I was running two 50 watt HD ceramic mag 12's at the time. But with the 5E3 vol and tone pot setup, like they are, it brokeup as soon as the amp was set at 2 . 

 Now since I changed the 12ax7 to a 12at7 in V2 I can tell the break up is smoother , I kept the 12ay7 in V1 .

 Still it does seem to me that all I have done for the most part is make the amp breakup later at a higher vol setting.

 I haven't moded anything in or past the output tubes other than the larger OT and speaker. It may be the speaker since it is a far cry from the two 50 watt twelves , in fact one was a eminence tonker and the other a weber 50 watt silver bell I think the tonker was over 100 watt . I did have the silver bell in this build with this cab and it was much tighter but again I never got it past 3 , usually I would plug into the low input so the vol pot was at least useful but I could not get any highes with the silverbell by itself for some reason. I guess with both 12's the tonker took the bass more and had more high end , the tone pot was either all bottom or a bit less bottom so I changed the coupling caps and that helped some but not enough. I got the weber sig 12 alnico and then I had bottom and mids and highs and with that came the raspy breakup. it was a trade off I was willing to live with. Was is the word here.

 Yet it does seem just by changing the V2 to an 12at7 cut the rasp in half . I lifted the bypass cap on V1 but all it did was allow me to turn up the vol more but the rasp was still there , not as bad but there none the less. I seemed reasonable when I switched out the V2's bypass cap and added the NFB loop I would get less rasp but all it seems to do is again allow me to turn the vol up more and the raspy OD is almost the same as with the bypass cap and no NFB, it's just a bit tighter but it sort of kills the highs . I have no idea what I created here. I certainly don't need 2 twelves and can't afford another speaker and don't have the desire to put this build in the larger taller cab I had it in but what I can do is put one ten I have left in that cab and run 4 ohms using the 12 I have now and see if that changes things . I put the chassis back in it's original cab because the other one is to big to haul around , I must have been out of my mind building that thing. I also think I made a mistake putting the switch with the NFB lead on it right next to the input jacks and that may be adding some issues too. I just know there must be something I can do to get this thing more into the area I want it to be using what I now have to work with . My other thought was to use the BF tone stack since as you know the brown face tone stack has less loss so then I may be in SF princeton territory since I already have the voltages close to that. Seems what I have now is just a high voltage 5E3 with a loss loss tone stack and a speaker that can't handle breakup very well and an OT that lives on bass. But I am not giving up yet. So far the only thing that offers hope is my wife did say my amp sounded  a lot better after I put in the 12at7 and she did notice the raspy breakup before,she commented on it , said it sounded like the TV up to loud buzzing the metal book case behind it. I know in this long reply I am contradicting myself.I started this build from the wrong end now I have to back peddle.

 I know a few people that have the brown 6G2 with both the oxford and later ceramics they said the Oxford breaks up sooner and is brighter they like it better for blues.

[HotBluePlates]

HBP has left the building.

[catnine]

 I have one more possibly stupid question on lead dress.

This is a close up shot of the switch I installed to either take out the V2 bupass cap and add in the NFB of switch it back stock.
here is what bugs me since I did this. This is about lead dress.

 you see how I took the + end of the bypass cap and soldered it to an eyelet from the eyelet it goes to the right lug on the switch via a short lead. If the switch keeps the bypass cap in circuit then to goes through the switch to a white lead on the left side of the switch back to the eyelet across the 1.5K cathode bias resister which in turn sets the bias for the second gain stage right before the PI triode.

 Once the switch is thrown the white lead and the green NFB lead on the left side of the switch are now connected , bypass out NFB in.

 Then you see a white lead dropping down right next to the green NFB , the white lead goes to pin 2 Grid of V2 from the vol pot wiper .

 Then you see a yellow lead to the right of the switch dropping down . This yellow lead is off the tone pot wiper to the vol pot outter lug through a .02uf coupling cap to the 100K ohm plate load resister to pin 6 (plate) of V1 .

 My point , since the switch is so close to the input jacks as is the NFB lead off the output jack + lncluding the vol pot and tone pot leads might this cause an issue AK bad lead dress perhaps causing as issue ?

[Willabe]

Catnine, I looked back at my post and would like to apologize for not saying that I hope your situation gets better very soon.


          Brad     

[Ed_Chambley]

If you look at reply #26, you will see where I mentioned Gain=Distortion in your definition.  Why shouldn't we think this way.  Every time we see a knob marked Gain and turn it up, we get distortion.  So I went on the assumption that you wanted to reduce distortion and not gain.

I have a build very close to what you are doing.

Things you mentioned that were contradictions.
1. Why I said to put the 12Ax7 in the PI and the 12Ay7 in v1.  If you put a 12Au7 in V2 it will reduce Gain even more, but you are correct, all it will do is allow you to turn the amp to a higher number.  It will not be louder and clean.  The suggestions you received are correct and will reduce gain.

2. The reason I said to put off the Paul C. mod is I begin tweaking at v1 and them move to v2 ( it doesn't have to be done this way, it just works for me).  All the Paul C. mod is removing one resistor and putting in another.  If you want to know how to do it, I will find a schematic and post it.  It is said this mod will make the distortion more symmetrical.  I did one on a couple of princetons, but I did not need to do it on the 5E3.  Doesn't mean you cannot do it or will like it for that matter.

3. I am not a fan of the 5E3, but that is no secret.  The reason is I like loud clean and punchy.  So I began tweaking with the attitude I will get this thing the way I want it.  I did.  You seem to like volume numbers, so I will say you can turn it up to 10 on either volume and it is clean, it goes to 12.  This is with a 12Ay7 in v1 and a 12Ax7 in V2.  This is where breakup begins and it is loud, very loud and clean.

4. As I mentioned before, someone who likes the 5E3 sound would not like this amp and why worry about preamp bias if it sounds like you want.  I am not in any danger of burning up the tube.

Finally, I understand having hard financial times and cannot afford throwing away money on amps right now.  I may be wrong, but I do feel keeping the gain up and changing a few caps to lower values will get you closer to what you are looking for.  More of singing quality as opposed to distorted sound the 5E3 is famous for, but I cannot know for sure.

Solution: If this is what you are looking to do, PM me with your address and I will be happy to send you some caps to try.  Like I said, they are very inexpensive and you can return them when things get better for you.