The importance of sag?

[SILVERGUN]

I have a Hoffman AB763 type build in my sights....I have no real ties to tradition and I'm not trying to make an exact clone
,,,but I played a Deluxe Reverb re-issue over the weekend and really enjoyed the "feel" of the cleans

How important is the tube rectifier sag to achieving that great vintage clean sound/feel?,,,and would it even come close to use SS?.. with a sag resistor?

Is sag evident at low volume when you're not really pushing the amp, just because the tube rec. is there?....because this thing had great tone all the way down on 2 on the Vol.....I just plugged straight in, turned all the tone controls to 5 and could have sat there all afternoon

Would it be silly/stupid to build this amp type and not use tube rec?
I know what the purists would say,,,what about the progressives?

[stratele52]

IMO sag have noting to do with the great vintage clean sound / fell.

The original Deluxe Reverb is a great amp the most sough after of Fender amp . Great sound is about it desing not only the tube rectifier and sag. A good clone will do the job.

Yes a resistor in power supply will do sag.

[jojokeo]

Hey SG!
I like a certain amount of sag when playing blues and/or slow style passages but not when playing rock/faster playing. It seems to only make me slow down and I don't get the attack I want when playing faster stuff. Rectifier or resistor will accomplish the same thing. But why not have the option for both? Flip a switch for sag and back for no sag. Make it what YOU want.

Yes the cleans are awesome but so is the reverb on ol' Fenders. I've held onto my SFSR through the years to get the mojo when I'm in the mood and my bandmate's got a '65 BFDR to jam into whenever the need arises. The DR is a great amp for sure but there's no simulating having 4 speakers pushing air vs only one.

ps - it's not allowed adn very bad karma to begin a new project until sound files are shared on an old one first!!!

[tubenit]

I like a certain amount of sag when playing blues and/or slow style passages but not when playing rock/faster playing.

I think Jojokeo is right on the mark with that statement. I have a friend who can play so fast that he needs solid state rectification to clearly keep up and fully sound all the notes. (At least it's seems that way to me.)  In contrast, I am rather slow in my playing so tube rectification works out fine for me. 

Having said that,  one thing I like about tube rectification is that I can change voltages   5Y3GT  1.1 X VAC,  5V4  1.2 X VAC or GZ34  1.3 X VAC.   That actually allows me to play 6K6, 6V6 or 6L6 in one of my amps that has 275-0-275 PT.

Just a thought!

With respect, Tubenit

[jojokeo]

Having said that,  one thing I like about tube rectification is that I can change voltages   5Y3GT  1.1 X VAC,  5V4  1.2 X VAC or GZ34  1.3 X VAC.   That actually allows me to play 6K6, 6V6 or 6L6 in one of my amps that has 275-0-275 PT.

+1 tubenit!!! I do that also for my Tweed Super Deluxe and I also have a Weber copper SS recto even though this can be designed with a switch & diodes. But on the very tight/small tweed chassis it's easiest just to put the copper recto in.

[SILVERGUN]

Thanks guys,

Do you think it has anything to do with the touch sensitivity of the amp?

I like that feeling of "streching the note" and working it around a little, and wouldn't want to lose that

There is a feeling of elasticity in those cleans, that makes me want to play slower....is that sag?

[jojokeo]

Also for newer Fender amps, the supersonic sounds very good on cleans

[Ed_Chambley]

Best way I know to describe it is SS id BAM BAM BAM and sag is wooooooosh, wooooooooosh, woooooooosh.

There is really no need for a tube, except for the cool factor.  Tubes are cool.  
+1 on the weber copper caps.

If it makes any difference fender SS amps lend themselves well to twang.  I also have 3 Super Reverbs.  My favorite amp all around.  I have an original JTM 45 with tube rectification and it sags heavily.  Very cool version of the Bassman.

It is all about the attack you need.  If I am shredding, I am using a Fargen Old 800.  If I am playing pretty I like sag.  I also prefer sag when doing rhythm.

All that said, you may not want advice from me.  I prefer Humbuckers through a Marshall Plexi when playing blues like the Allman Bros do.

But the handwired AB763 is so much better sounding than the reissues.  Not that they are bad, the new reissue Bandmaster is killer, but in the deluxe I like a Blackface best.  It is a perfect small club amp.

[Ed_Chambley]

Hey SG!
I like a certain amount of sag when playing blues and/or slow style passages but not when playing rock/faster playing. It seems to only make me slow down and I don't get the attack I want when playing faster stuff. Rectifier or resistor will accomplish the same thing. But why not have the option for both? Flip a switch for sag and back for no sag. Make it what YOU want.

Yes the cleans are awesome but so is the reverb on ol' Fenders. I've held onto my SFSR through the years to get the mojo when I'm in the mood and my bandmate's got a '65 BFDR to jam into whenever the need arises. The DR is a great amp for sure but there's no simulating having 4 speakers pushing air vs only one.

ps - it's not allowed adn very bad karma to begin a new project until sound files are shared on an old one first!!!

I am going to die soon.  My Karma is soooooooo bad.  Is it better Karma to use backing tracks, or simply record the amp alone.

[jojokeo]

I am going to die soon.  My Karma is soooooooo bad.  Is it better Karma to use backing tracks, or simply record the amp alone.

Wicked funny Ed!    Anything will work too!!! The spirits in the sky are not picky spirits. You get bonus credit for actually playing spirit in the sky too!!! ;)

But the handwired AB763 is so much better sounding than the reissues.  Not that they are bad, the new reissue Bandmaster is killer, but in the deluxe I like a Blackface best.  It is a perfect small club amp.

+1 on that one big time. There's another bandmate on the same side of the stage with the re-issue DR (alternates between guitar, bass, and acoustic). So the original & reissue sit side by side together and you can really hear it like that.

[SILVERGUN]

ps - it's not allowed adn very bad karma to begin a new project until sound files are shared on an old one first!!!

Notice how I dodged that one......
Alright I promise  that before I begin a new amp I will put up some clips of the Dr.BognerSoldanoTurboWreck 

Just taking notes right now....and the list is getting longer
-AB763, TOS, Bassman, Plexi6V6, SSS, Dum#102, 1987, SLO, etc,. etc., etc.....

I'm getting close to finishing the breadboard, and then it's ON

[kagliostro]

I'm getting close to finishing the breadboard

Of course we aspect to see some photo from you 

Franco

[HotBluePlates]

Muddying the waters with the original question:

How important is the tube rectifier sag to achieving that great vintage clean sound/feel?

It depends on what the player considers "vintage" sound/feel. Some vintage amps had sag, some didn't.

It depends on how you define sag and whether that's slang for voltage droop due to poor regulation, or if it's a sonic effect. Voltage droop when pushing max power might lead to the sonic effect of compression. Yet a Champ, which should have a largely constant supply voltage because current draw is nearly constant also has compression when it's heavily distorted.

Onset of output tube distortion (and preamp distortion in the case of master volume amps) will probably give some impression of sag/compression.

Is sag evident at low volume when you're not really pushing the amp, just because the tube rec. is there?

No, it isn't (or shouldn't be).

Here's why:
Assume you have a class AB amp. You already know that what makes it AB is that after some amount of drive signal, the tube(s) on one side of the OT will shut off while the tubes on the opposite side conduct much more current. However below that drive point, one side draws less current as the other side draws more current. When both sides are conducting, the action of one side is then offsetting the action of the other, and current drawn from the power supply is largely constant.

If current draw is constant, or varies only slightly, the voltage dropped across the rectifier or power supply impedance must also stay largely constant. So "sag" caused by voltage drop can't occur, can it?

It's my opinion you can't really evaluate sag/compression without pushing the amp close to its output power limit. However, you can evaluate the amp's tone at any volume setting. If you like the tone/response at low volume, then you like the amp. It may respond differently when pushed, or not... you have to crank it up to find out.

I never played on stage much; I loved the sound of all my old Fender amps even clean at low volume. All seemed to have a warm, tubey response that was nothing like the solid-state amp I had when first picking up the guitar. Apparently, sag wouldn't be the (only) deciding factor in my case, for my taste. But no one has to agree that what I like works for them, so you really have to try for yourself to find what works for you.

... I played a Deluxe Reverb re-issue ...

Would it be silly/stupid to build this amp type and not use tube rec? ...

I never measured current draw of the Deluxe Reverb during driven conditions. I have a hunch that with 6V6's, the amp doesn't draw massive current from the power supply, so with a GZ34 (lowest voltage drop in a common guitar amp rectifier) the sag is probably minimal. That said, filter cap sizes enter into the equation. But the fact that players can generally perform with a band in a smaller club with a Deluxe Reverb tells me it has a certain amount of punch.

If you're building from scratch, why couldn't you have both a solid-state and tube rectifier, perhaps with a switch to select which you're using. You could compare for yourself and see what you like. Note that the lower voltage drop of the solid-state under all conditions will mean some amount of tonal difference just due to higher supply voltage throughout.

[SILVERGUN]

Muddying the waters with the original question:

As always,,,thanks for staying with me HBP

If you're building from scratch, why couldn't you have both a solid-state and tube rectifier, perhaps with a switch to select which you're using. You could compare for yourself and see what you like.

Yeah,,, with the breadboard on the way, that's definitely going to happen.....I just like to hear what the panel has to say....
I've been drinking the Mesa Boogie "Kool-Aid" for soo long that I am now enamered with everything else and just trying to get the cliff notes on this stuff from the guys that have actually been paying attention for the last 20 years
In an amp,,,I'd hate to build in extra circuitry if it's not needed,,,,,and I never buy just the "Deluxe Reverb Power Transformer" without looking at my options for more current.....so if I don't need the 5V tap, it changes the options............guess that's where the beauty of the breadboard will show up,,,I can figure it out ahead of time

That said, filter cap sizes enter into the equation.

And thats partially where I was going with this question....I always like a lot of bass response, and it's my understanding that a bigger first filter cap will help,,,,so if I don't care about losing the potential for sag, then I can go SS and "beef" things up a bit

I just want to make sure that giving up sag isn't giving up FEEL 

[SILVERGUN]

All that said, you may not want advice from me.  I prefer Humbuckers through a Marshall Plexi when playing blues like the Allman Bros do.

I really appreciate everything that ALL of you guys take the time to type...and I read it all....I wish I had the kind of experience that you guys have

This is one of those questions that obviously has a lot to do with personal taste.....and I'll never really know until I get one of these amps up past 7...right?

[Ed_Chambley]

All that said, you may not want advice from me.  I prefer Humbuckers through a Marshall Plexi when playing blues like the Allman Bros do.

I really appreciate everything that ALL of you guys take the time to type...and I read it all....I wish I had the kind of experience that you guys have

This is one of those questions that obviously has a lot to do with personal taste.....and I'll never really know until I get one of these amps up past 7...right?

Not always SG, but you get the idea.  A booster like a BB or RC (my personal choices, there are many) will increase signal and therefore cause sag and will do it lower than diming the amps.  Also HPB gave me a tidbit I will pass along.  Increasing the screen resistor value will cause the amp to sag earlier.  Since he mentioned this to me I have been trying different values.  It even works in a SS rectification.  The benefit to it over a sag resistor is less heat.

[HotBluePlates]

...  Also HPB gave me a tidbit I will pass along.  Increasing the screen resistor value will cause the amp to sag earlier.  ...

The potential drawback is by using the resistor to increase sag/compression, you are also reduce the maximum power output of the amp... either a little or a lot, depending on how large you make those resistors. Whatever size you make them, they don't cause an audible sonic effect until they're limiting the output power to some degree.

So it still comes down to pushing the amp somewhere near its limits. Really, this is the range I think guys who are really into tube amps (I should say some guys, some styles) like to hang out; i.e., pushing the amp's output stage to its limits to generate output tube distortion and use sag/no-sag to influence the sound. Aside from mid-scoop, the clean sound of my old '54 Princeton, '73 Marshall 50w and Hiwatt DR504 didn't sound that different. Cranked, they all have a different personality.

But the over-sized screen resistors is a trick that does work, is cheap and easy to incorporate. As Ed says, it doesn't waste as much heat into the chassis.

[kagliostro]

Mesa Boogie do the trick (switchable) in the Lonestar

K

[HotBluePlates]

Interesting. I had no idea they did that.

[kagliostro]

I had no idea they did that

This confirm the high quality of your mind 

K

[Ed_Chambley]

Ed

Experience, Experience,

From your posts, I am sure you have acres and acres more experience in the amp building/repairing area than I do.  Drgonzonm

Probably not in reality my friend.  I am learning.  Sluckey, Dummyload, PRR, Willabe, and HPB are tremendous.  I am now bugging Jojokeo and pulling him from the fuzzy underworld.  I am simply a thorn in their side stealing as much info as I can.  Well that and I am an amp collector.  By that I mean an investor.  Necessity has made me learn.  In reality before becoming a member of this forum I had never built anything outside of typical Marshall designs with a few mods.  I collect mainly Marshall, but have gotten into some others.  It all started with a Kitchen/Marshall purchase about 15 years ago.  I got the original with the original cab.  Paid $700.  Perfect original condition.  It quickly became worth more than I would have imagined.  That lead me down this path.  Also I collect Zeneth Giants, Hammond Organs and Leslie cabs.  I had to learn how to maintain these or any profit would go to repair labor.
If I ever make a correct comment, I promise it was taught to me by the fine people here.  Well except for radio and metal fab.

[Ed_Chambley]

...  Also HPB gave me a tidbit I will pass along.  Increasing the screen resistor value will cause the amp to sag earlier.  ...

The potential drawback is by using the resistor to increase sag/compression, you are also reduce the maximum power output of the amp... either a little or a lot, depending on how large you make those resistors. Whatever size you make them, they don't cause an audible sonic effect until they're limiting the output power to some degree.
 

I agree it could be considered a drawback by limiting power.  Overall with the desire to make amps that can get into power tube distortion I have found the power loss in negligible and can easily be compensated.  What I mean is my SuperfrankModded73sortofAb763 reverb is/was too loud to play in most places if I want tube saturation.  I tried many different values and really liked every increase, but did not want to lose the killer tone of the amp.  I ended up making it switchable with 3 different values and they actually "simulate" a low power switch in a weird way.  There is a noticeable loss in highs when switched to 4meg in series, but turning the mid back just a little lets the highs shine, however the amp takes on a different tonal quality that is nice.  It just makes you play Red House and I am really not a bluesman.
I would say this is the best trick I have been taught in regard to the effect it has on the weber alnico speakers.

[Geezer]

...  Also HPB gave me a tidbit I will pass along.  Increasing the screen resistor value will cause the amp to sag earlier.  ...

The potential drawback is by using the resistor to increase sag/compression, you are also reduce the maximum power output of the amp... either a little or a lot, depending on how large you make those resistors. Whatever size you make them, they don't cause an audible sonic effect until they're limiting the output power to some degree.
 

I tried many different values and really liked every increase, but did not want to lose the killer tone of the amp.  I ended up making it switchable with 3 different values and they actually "simulate" a low power switch in a weird way.  There is a noticeable loss in highs when switched to 4meg in series, but turning the mid back just a little lets the highs shine, however the amp takes on a different tonal quality that is nice. 

Ed, can you provide a diagram (or description) of the switching you did, or at least the values you used and whether parallel or series connected?

G

[SILVERGUN]

Great stuff guys...
Wherever this conversation goes,,,,I'm with it because I'm learning as we go

THANK YOU ALL!

K, you never cease to suprise me with the stuff you pull out 

[HotBluePlates]

There is a noticeable loss in highs when switched to 4meg in series ...

I never tried any value approaching 4MΩ. Max I've tried before was ~10kΩ, but if it's working for you then it's good to go.

[Willabe]

Sluckey, Dummyload, PRR, Willabe, and HPB are tremendous.  

         

Ed that's very kind of you to put me in with those guys, but like you I'm just learning.


              Brad      

[Ed_Chambley]

...  Also HPB gave me a tidbit I will pass along.  Increasing the screen resistor value will cause the amp to sag earlier.  ...

The potential drawback is by using the resistor to increase sag/compression, you are also reduce the maximum power output of the amp... either a little or a lot, depending on how large you make those resistors. Whatever size you make them, they don't cause an audible sonic effect until they're limiting the output power to some degree.
 

I tried many different values and really liked every increase, but did not want to lose the killer tone of the amp.  I ended up making it switchable with 3 different values and they actually "simulate" a low power switch in a weird way.  There is a noticeable loss in highs when switched to 4meg in series, but turning the mid back just a little lets the highs shine, however the amp takes on a different tonal quality that is nice. 

Ed, can you provide a diagram (or description) of the switching you did, or at least the values you used and whether parallel or series connected?

G

Sure, impedance selector switch, 4 positions.  Lifted the screen wire and attached to the center.  First position is 470ohm/3 watt both screens.  Second is a 1k5 meg/3 watt, third is 2k2/3watt and 4th is 4k/3watt.  All are 3 watt.  Yes it is sort of a hatchet job as I use what I had.  I put the resistors on the selector switch and tied pin 4 to 6 and each pin has 2 wires on it to keep me from having to solder 4 wires to pin 4.  I was sure it was going to cause noise, but it hasn't.  Also, there is no measurable voltage on any of the non-connected resistors as I used a diode for each connection on the tube.  I don't know if there would be, but diodes are cheap insurance and keeps me from having to think.  Things do not go well when I think too much.

I have not had the nerve to switch it while on as I think it would be a bad idea and probably pop as well.  At the very least there would be a moment where there is no contact.  I did not know if I would like it, so now I am going to find a better way to do it.  Probably will use a relay, but I am still sort of experimenting with values. With a relay I could keep the stock resistor tied to the screen and simply add the others in series and not run the risk of ever losing screen current.

That's the general info. Let me know if you can think of a better way as you are far better at this stuff than me.  It is cool and I would like a better way to do it.

[Ed_Chambley]

There is a noticeable loss in highs when switched to 4meg in series ...

I never tried any value approaching 4MΩ. Max I've tried before was ~10kΩ, but if it's working for you then it's good to go.

I was wrong.  I posted this way too early.  Meg should have been K.  Sorry.  The largest I liked so far is 4k.

[Ed_Chambley]

Sluckey, Dummyload, PRR, Willabe, and HPB are tremendous.  

         

Ed that's very kind of you to put me in with those guys, but like you I'm just learning.


              Brad      

You have helped me a lot.  I don't think it is all about what someone knows, but how much they care.

[Willabe]

Again, very kind of you Ed, thank you. This is a good place to be, with good people and it kinda rubs off on you.

Now back to our regularly scheduled program.  And'a 1, and'a 2,    


            Brad    

[moonbird]

You have helped me a lot.  I don't think it is all about what someone knows, but how much they care.

Agreed! thx Brad!

[SILVERGUN]

Sluckey, Dummyload, PRR, Willabe, and HPB are tremendous.  

Anytime you make a comment like that, you run the risk of leaving someone out....
I'm glad you mentioned jojo later (and he is tremendous),,,,,BUT, let us not forget to give praise to the mighty tubenit

If I was getting paid for building amps, I couldn't live with myself if I didn't send them a large percentage of the money!

Nice job of turning a simple question into a very informative thread.......I'm not shocked  

Ed, do you live anywhere near Philadelphia?......I have a feeling that visiting your collection would be like my version of going to Graceland  

[moonbird]

And to you Silvergun - you facilitate GREAT threads Sir!!  

[Ed_Chambley]

Sluckey, Dummyload, PRR, Willabe, and HPB are tremendous.  

Anytime you make a comment like that, you run the risk of leaving someone out....
I'm glad you mentioned jojo later (and he is tremendous),,,,,BUT, let us not forget to give praise to the mighty tubenit

If I was getting paid for building amps, I couldn't live with myself if I didn't send them a large percentage of the money!

Nice job of turning a simple question into a very informative thread.......I'm not shocked  

Ed, do you live anywhere near Philadelphia?......I have a feeling that visiting your collection would be like my version of going to Graceland  

South of Atlanta.  I have sold the Kitchen/Marshall and saw it on ebay last month.  Guy is flipping it for about $5000 profit.  Did not sell.  The only unique valued amp I have is an original jtm 45 and 64 Super Reverb.  When I finish the restoration on 62 bassman, I will have 1 more.  I only have 11 amps at home, the organs and leslies are in the paper warehouse of my printshop or should I say paper is stored in my organ shop.

It is not Graceland.  When I read this I heard Elvis complain.  It is true you do leave people out and I am sure I will when I accept songwriter of the year at the CMA's 
I have lots of organ stuff for sale which mainly goes to churches.

[HotBluePlates]

... First position is 470ohm/3 watt both screens.  Second is a 1k5 .../3 watt, third is 2k2/3watt and 4th is 4k/3watt.  

...

... Let me know if you can think of a better way ...

Do you like all 4 settings and want to keep all of them? Said another way, are they all different enough from each other that you want to keep each?

[Ed_Chambley]

Not really.  The 1k5 is not really noticeable, but I have not tried and thing larger than 4k.  I plan to.  If you idea is to get 3 or 2 different values, lets here it.  Like I said, I just used what I had and still cannot believe it worked so well.  I could really live with 2 values, once I find the right one.

[burt_toast]

+1 about the booster/sag thing.
Ed_Chambley said "A booster like a BB or RC (my personal choices, there are many) will increase signal and therefore cause sag and will do it lower than diming the amps. "

yes! i can get a Sonny Landreth-style sag if i push the ex-bandmaster real hard - beautiful...

scott

[HotBluePlates]

...  If you idea is to get 3 or 2 different values, lets here it.  ...  I could really live with 2 values, once I find the right one.

Let's assume the 4kΩ and 470Ω values are must-haves. And maybe 2.2kΩ is a middle-ground (you might in the end decide on an even higher value, or not depending on what you think after listening).

Instead of switching to a discrete resistor for every value, have the highest value always in the circuit. Then switch an additional resistor in parallel to get your lower values.

Ex:
4.7kΩ is always between the screen supply node and the screen, and is your highest-sag setting. A switch then adds 560Ω in parallel. The resulting total resistance is 500Ω.
-  The above could be switched with a DPST switch and control both output tubes of a push-pull stage.
-  4.7kΩ and 500Ω become your highest sage and lowest sag settings, and are approximations of what you started with using easily-available single resistors. If you have to zero in on a more exact setting that's not one of these, different series-parallel combinations can be done, but complicate switching.

Ex 2:
Same circuit as above, but now you want to add a ~2.2k setting. A 4.3kΩ resistor in parallel with the 4.7kΩ yields 2245Ω, which is effectively the same as a 2.2kΩ resistor as it's only 2% higher than 2.2kΩ.
-  Rather than a normal DPDT switch (center off) to get these 3 values, which would make the center position the highest sag, it's possible to find switches that have progressive action to have the resulting resistances be Low-Medium-High so the switch is intuitive. The switch might be more expensive and you'll have to spend some time with a switch catalog to figure to correct one and the best way of wiring it (I figured out something similar for Triode-Ultralinear-Pentode switching for an amp).

[PRR]

> First position is 470ohm/3 watt both screens.  Second is a 1k5 meg/3 watt, third is 2k2/3watt and 4th is 4k/3watt.  All are 3 watt.

Diodes in the G2 connection are a *bad* idea on 6L6. G2 current can go *negative*.

> the nerve to switch it while on as I think it would be a bad idea

Going-open won't hurt the amp... it basically goes "off". This may pop more or less.

However: you could nail the 4K in place permanently. That's your 4th position, so G2 never goes stone-dead. For 3rd position put another 4K (or 4K9) in parallel; makes 2K2. 2nd position 2k4 (or 2k2) with the 4K makes 1k5. And 1st position is 533 (or 470).

While it may pop, I suspect it won't be noticed in a bar (maybe a wedding).

I suspect the 4K could be larger than 3 Watts, especially with EL34. (I used a 10W mostly because it was the only several-K that I had in hand.)

***Ah, I see HBP beat me to it.
________________________________

> I'm just learning.

We are all just learning.

[tubeswell]

I whole lotta love like a bit of sag and bloom with maxed out distorted geetar - especially when doing some of the Zeppy stuff, like Whole Lotta Love, or Rock'n'roll, or Communication Breakdown

[Ed_Chambley]

Diodes in the G2 connection are a *bad* idea on 6L6. G2 current can go *negative*.
 

[/quote]
Since we are all learning.   How could g2 go negative caused by a diode?

[HotBluePlates]

Diodes in the G2 connection are a *bad* idea on 6L6. G2 current can go *negative*.

Since we are all learning.   How could g2 go negative caused by a diode?

Just guessing, I think PRR was not saying the diode will cause G2 to have negative current or voltage, but that in normal use G2 current flows in both directions (positive and negative) and that fact makes the diode a bad idea.

I'm just learning this too, so I'll defer to PRR for more info.