Spin Off of 2015 list (5E9-A) Im gonna build the 5G9 instead

[lego4040]

Correction made, thanks Steve

[sluckey]

Hammond 290Cax...
   6.3v/2a is perfect for this amp.
   5v @ 2a is fine too, just don't use a 5U4. Plenty of other 5xxx rectifiers to choose from.
   The choice of which HT winding to use can be a plus factor.
   You don't need a bias tap to develop bias voltage. Look at the Princeton Reverb.
   You already got it!

The Allen PT looks good too, but it won't do a 5U4 either. 6.3v @ 4.5a is overkill, but works fine. Does anyone even use 5U4s anymore?

[lego4040]

I was just looking and will swap rectifier to a 5y3, done. Hammond 290cax it is. I will put that on the spread sheet. I hope to work on sheet more tonight but my main goal is to have my board/ resistors and some others ordered tonight. I'd love to get this 100% done and give everyone here a chance to build with out having to go crazy sourcing parts. Stomach virus going thru house past week just put my Kids nanny out of commission

[Willabe]

That's tight Wallibe mentioned that the 6.3 or the 5volt didn't have enough amperage.

So now I'm Wallaby, or how ever you spelled it?     

You need 3A's for a 5U4, but you can use a GZ34/5AR4 or a 5V4 with a 2A wind. Might be fine.   


             Brad     

Edit; I see I'm late with this.

[lego4040]

  Willibe, sorry.

[Willabe]

No problem, I'm just jokin with ya.


         Brad     

[lego4040]

ordering parts now, I have a question on the speed pot for this circuit. I will replace the 2mra and use the 3mra, should I wire it like the rest of the fenders here with leg2 going to 100k to ground?

[sluckey]

It'll work equally well either way. Even so, if I was building a 5G9 I'd follow the 5G9 schematic.

[lego4040]

The only reason why I am changing that to a 3mra is because I cant locate one

[Willabe]

to a 3mra

Not to be a nit picker, but - m = mili , - M = Meg

The 3MRA pot will be fine and if anything will slow down the trem speed a hair? It's what I have in mine.


                 Brad   

[sluckey]

The only reason why I am changing that to a 3mra is because I cant locate one

I know that. My answer pertains to your question about how to wire the pot.

[lego4040]

Ah I see Steve, I will do that. Doug says he'll make the Board on natural color turret

[Willabe]

Hammond 290Cax...
   6.3v/2a is perfect for this amp.
   5v @ 2a is fine too, just don't use a 5U4. Plenty of other 5xxx rectifiers to choose from.
   The choice of which HT winding to use can be a plus factor.

Sluckey's right of course. 

I bought the Merc Mags iron to get pretty close to the old 5G9 power supply (PSU) voltages and current plus the 5U4 rectifier, but that doesn't mean you can't do it other ways with other iron and rectifier tubes. And I already have a 5E3 I built with a 5Y3 rectifier in it. I wanted to hear/play a PP 6V6 15/20w amp with a possibly little 'stiffer' PSU (5U4) to hopefully hear what a 5G9 sounds like. I wanted something a little cleaner but still with the tweed warmth and the trem was a HUGE bonus!

I was also very curious what difference in sound and feel the -bias output stage and LTPI would make compared to the K bias and concertina with the same pre and same 12" speaker. For me I like the 5G9 much better and I think a LOT of guys, but not all, would too!

I also think that IF G. Weber would have talked about them as much as he did other Fender tweed amps in Vintage Guitar Mag. and/or Mark B. at Victoria amps would have been making them early on and had a chassis made and sold it/gave it to Mojo music it would be a very different story right now.     It wasn't 1 of the classic amps that were cloned early on, so you couldn't just buy a pre punched chassis, eyelet board, iron set and cab for it.     

Anyway, did Leo switch from a 5Y3 in the tweed deluxe 5E3 and tweed Tremolux 5E9A to a 5U4 in the 5G9 for a little cleaner, stiffer PSU? Was he experimenting? Or got a deal on them? All of the above? 

Different rectifiers can handle different loads and will start to compress (sag) sooner then other rect. tubes. I posted some rect tube #'s on current handling some posts back to show this.

If you don't push the amp hard the rect tube won't be taxed and will be able to keep up so no real difference in playing touch/feel and sound.

Depends on where you think you will set the volume most of the time. You can think of it as a built in tube compressor where you can set the amp at a certain volume where along with riding the volume control on your guitar, so that when you pick soft it will be clean and when you pick hard it starts to break up along with some compression. Touch sensitive. (It will be different on different amps, a big factor in having different sized amps for different sized gigs/rooms so you can turn up the amp to that point without blowing everybody out of the room)

I don't play out anymore and I never really did turn my amp past 6 or so and that was with a BF SR and 4 1/2 is still really clean compared to other Fender amps. If I can get to 3 1/2 to 4 1/2 now I very happy with my 5E3 and 5G9. (I had a Mesa MII years ago with a single 12" that was SOOOOOO STIIFF I never got used to it. NOOOOO forgiveness at all. The least little thing and you heard it.   )

I think these are things to consider but........    Build it like you want.



                        Brad   

[lego4040]

That was a good read there Willabe, I see where your coming from. If I choose to buy a PT then why not buy the one that's made to those specs and allow me to use a 5u4. I'm not on a time schedule so I can put it to thought. Back when I was building Hot Rod Chevy's and driving them sometimes I would come up to another Chevy and we'd swap stories. When we open the hoods I'd have my Chevy engine in my Chevy car and they'd have a Mopar Hemi in their Chevy.  It's not a Chevy if it ain't 100%. It  does makes one hell of a Hot Rod but it's different

[Willabe]

If I choose to buy a PT then why not buy the one that's made to those specs and allow me to use a 5u4.

Maybe yes, maybe no. I'm trying to unconfuse what I may have confused up.   

Back when I was building Hot Rod Chevy's and driving them sometimes I would come up to another Chevy and we'd swap stories. When we open the hoods I'd have my Chevy engine in my Chevy car and they'd have a Mopar Hemi in their Chevy.  It's not a Chevy if it ain't 100%. It  does makes one hell of a Hot Rod but it's different.

Yes and there's more than 1 way to skin a cat.

The suggestions Sluckey and DL gave are very good choices. They may sound just as good or better as the Merc Mags iron with a 5U4 even if you have to use a different rectifier tube.

I'm not trying to convince you to go with what I went with. I was just trying to say why I choose what I did, even though my thinking on it is debatable.

Sluckey and DL won't steer you wrong and know more than I do.   


                Brad     

[lego4040]

Meat and potatoes ordered last night. Chassis,OT, capcan& choke needed to complete

[lego4040]

I was just reading up on a LouisElectric Tremolux based amp and he has the 5AR4/GZ34 Rectifier in it. hopefully today Ill pick up a OT and Chassis.I still am a little undecided on which Pt to get??? I will more then likely go with the

Mojo768sp from here

[Ed_Chambley]

I was just reading up on a LouisElectric Tremolux based amp and he has the 5AR4/GZ34 Rectifier in it. hopefully today Ill pick up a OT and Chassis.I still am a little undecided on which Pt to get??? I will more then likely go with the

Mojo768sp from here

I have a theory that has served me very well.  When in doubt, lower the voltage.  The trans you mentioned will work fine, but Edcor has one with a 50v bias tap.  Just takes a little while to get it.

[Willabe]

I was just reading up on a LouisElectric Tremolux based amp and he has the 5AR4/GZ34 Rectifier in it.

I just looked at his site and his 5G9 knockoff says 'classic 6L6 tone'. Must have changed it since the Tone Quest Report mag review.

The review he has posted is from and say's new Tung-Sol 6V6's with a new EH5U4, yet his spec. description lists 6L6's and 5AR4/GZ34.

He also added a presence control which means he had to add a -FBL which the old 5G9 does not have.


                          Brad       

[lego4040]

Mistake, it was the OT i wasnt sure about really. Steve you had said I didn't need the bias tap, just look at the Princeton reverb. If I use the Hammond 290CAX which doesnt have the bias tap, What changes would I have to make? my other PT I have has the bias

[lego4040]

so looking at how the PR does its bias off the intensity pot seems like to much work out figure out and I don't want to deviate off the circuit

[Willabe]

No their similar. They both have the -bias connected to the intensity/depth pot because that's how they vary the -bias.

Just look at the -bias part.

5G9 has a bias tap, PR doesn't so they take the bias voltage off of 1 B+ secondary leg with a 100K R to knock down the ac voltage before they send it to the reversed bias diode. It's simple.


                Brad       

[sluckey]

so looking at how the PR does its bias off the intensity pot seems like to much work out figure out and I don't want to deviate off the circuit

The circuits are exactly the same! The bias voltage is fed thru the intensity pot on both amps. The only difference is the 5G9 uses a bias tap for it's source of AC voltage and the PR uses the HT winding as a source for AC voltage. That means you would use a big resistor (100K to 220K) between the HT winding and the bias diode rather than no resistor with the bias tap (or as I recommended, 470Ω like many of the AB763 amps use).

It's a one resistor change to compensate for 330VAC input to the bias diode rather than a 50VAC input to the bias diode.
 

[lego4040]

Ok, I'm flipping back and forth between both PR and 5G9 and I am seeing(I believe) what you guys are talking about. Take the leg from intensity pot that would be going to the triangular circuit on the 5G9 and set it up as the PR. I would then not have to use that triangular portion, it's inly for the Bias.

[Willabe]

I would then not have to use that triangular portion, it's inly for the Bias.

No.

1. To study and compare the circuits use the schematic not the layout drawing, much easy to see the circuits flow.
(Layout drawings are to find where the parts in the schematic are located in the chassis.)
2. Print them both out and look at them side by side, your going to need at least 1 if not both of them.
3. Start at the PT for the source ac bias voltage as Sluckey said, not the intensity/depth pot and work your way toward the 2x220K grid return R's in the schematic.

The 5G9 has a pi filter (cap/resistor/cap in the -bias supply to filter out the ac ripple from the diodes turn on/turn off, just like in the B+ PSU. The PR has only 1 -bias filter cap.

                        Brad   

[lego4040]

I have both layouts but left schems at shop. I totally see the pi you described and the single cap in the BFPR. I drew out two different ways and as I was drawing I could see how it might not work. I want to understand be able to decipher but aside from these forums and books/net it's still tough when you don't have someone to sit down with you and teach you. In my field of work HVAC we don't get this deep and their are no tubes. Thankfully the schooling has helped me with schematics.

[Willabe]

I drew out two different ways and as I was drawing I could see how it might not work.

Both circuits work.

You could use either circuit in either amp.


                     Brad   

[lego4040]

Well this is what I drew up first and it's the BFPR bias board schematic that I put on the 5g9 board, where the "pi" would be. How far off am I? I can handle it. Disregard bottom drawing

[Willabe]

You don't have a way to adjust the bias, ie, a bias pot.


                   Brad   

[sluckey]

You're making this way to complicated. Just build the 5G9 like the schematic/layout. Replace the selenium with a diode and resistor. Connect a 470Ω resistor to your PT bias tap if it has one. Connect a 100K-220K resistor to pin 4 or 6 of the rectifier socket if your PT does not have a bias tap.

Replace the 56K resistor on the board with a 50K pot and 22K resistor regardless of which PT you use.

See pic...

[lego4040]

I do tend to over think things I don't understand. As you see there was a second scetch I started and the third scetch I was thinking was the way you drew it out but I never got that far. I will compare schematics and follow. Thanks for all your help again and again.

[lego4040]

Steve, thanks for your help with that diagram, using your diagram this is how I will wire in the trim pot in the circuit where you show the 50k

[Willabe]

Ok here's my 5G9 and 5E3 build voltages;

5G9- NOS RCA 6V6's, NOS RCA 5U4GB, Merc Mag iron set, voltages taken with amp plugged into variac set at 120vac;

5U4GB; pins 4/6, each ~345vac, pin 8,  395vdc

6V6; 3. 388.4vdc, 4. 394.6, bias, 26.9, other tube; 3. 386.7vdc, 4. 394.7vdc, bias, 28.2 (measured through 1 ohm K R, pretty hot for 6V6's?)

Plate B+ node 395vdc, screen B+ node (after choke, 99.4 ohms) 397vdc

(Edit; Fender schemo for tweed Tremolux 5E9A lists 395vdc at 1st B+ node with a 5U4GA. But that would have been with 110ac wall voltage? Still 25vdc higher than the 370 listed on the 5G9 schemo. Who knows if either schemo is correct?)

PI; 1. 211.1, 6. 210.6

LFO/Driver; 1. 249vdc, 6. 389vdc

Pre; 1. 232.7vdc, 6. 224.7vdc

5E3- same NOS RCA 6V6's, NOS JAN 5Y3, 15+ year old Kendrick (Gerald Webber) iron set.

5Y3; pins 4/6, each ~362vac, pin 8, 362.6vdc

6V6; 3. 351.9vdc, 4. 319.2vdc, other tube, 3. 351.7vdc, 319.1vdc, K. 19.79vdc

Pre; 1. 124.7vdc, 6. 136.0vdc

PI; 1. 167.7vdc, 6. 229.6vdc

K; 19.79vdc

Yes the Merc Mag set gives higher voltages then found in the Fender schematic (plate, 370vdc, Merc Mag plate, 388vdc, not bad, only 18vdc+, but I am biased on the hot side and then some) but still lower then if I went with, say a DR PT.

PI is very close, on the $$ on 1 plate, pre, I'm 232.7vdc and 225.7vdc, Fender schemo, 175vdc, but I don't have a NOS RCA, I can change the B+ dropping R that feeds the pre B+ node and nail it.

Driver is 389vdc, Fender lists 368vdc, 28vdc higher, not bad, I have a separate B+ node for it so I could dial it in with the B+ dropping R. LFO is 249vdc, Fender 270vdc, so 21vdc lower, not bad, I don't know why 1 comes out higher and the other lower than in Fenders schemo, but the trem works fine. So I'm not worried about it.

I think I'm going to try a new 5Y3 and a NOS 5V4 rectifiers in the 5E3 and see where the B+ voltages end up.


             Brad   

[lego4040]

Thanks for those voltages, that will help me out when I get there. Question? Your Vac&Vdc are the same for the 5Y3?

[Willabe]

Thanks for those voltages, that will help me out when I get there.

There also to possibly help you with picking your PT.

Question? Your Vac&Vdc are the same for the 5Y3?

The vac and vdc are for the same rectifier tubes I listed. Why would I change them from what I listed to something else while still taking voltage measurements?

It would throw off the voltage measurements.


                      Brad                       

[lego4040]

Your 5U4GB; pins 4/6, each ~345vac, pin 8,  395vdc. Your voltage went up 50 as expected when converting to dc but your 5Y3; pins 4/6, each ~362vac, pin 8, 362.6vdc. Your Vdc only went up .6?

[Willabe]

I'll have to measure again. I can try another NOS 5Y3 or 2 also.


                   Brad     

[tubeswell]

I did a 5G9 using a PT with a 300-0-300 HT (@150mA) and a 3A 5V winding. Using a 5U4 and 40uF reservoir, I got 580V B+. If I couldn't find a PT with 300-0-300 and a 3A 5V winding, I'd try and work out the power supply to get the same B+ using a 5AR4 (instead of a 5Y3) because these amps like a stiffer power supply. So with a 5AR4, that'd want around 280-0-280 or 290-0-290 on the HT winding.

[lego4040]

What model Mercury did you use? Was it the FTTP/M with the lower B+? It's within my budget and whichever Rectifier I choose, I still need to buy. Another new Favorite Band of mine

[Willabe]

I did a 5G9 using a PT with a 300-0-300 HT (@150mA) and a 3A 5V winding. Using a 5U4 and 40uF reservoir, I got 580V B+.

580V B+?


             Brad   

[lego4040]

I been reading your thread you did over at music-(something) and remember you saying you used a FTTP/M. That's a incredible build. I went with the ClassicTone 40-18090 OT and got Hoffmans 125C3A small fender choke

[sluckey]

I did a 5G9 using a PT with a 300-0-300 HT (@150mA) and a 3A 5V winding. Using a 5U4 and 40uF reservoir, I got 580V B+.

You sure 'bout that? The maximum you could possibly get would be √2 x 300 = 424vdc. And that's with no load.

[DummyLoad]

I did a 5G9 using a PT with a 300-0-300 HT (@150mA) and a 3A 5V winding. Using a 5U4 and 40uF reservoir, I got 580V B+.

how is that possible? MAX in FW config is 424.2V AT 300Vrms. did you mean 480V?

480V would be realistic if the NL rating was 340V per 1/2 primary, however, 320-325V NL per 1/2 primary would be a more realistic figure for for a 600VCT 150mA PT.

--pete

[drew]

Hey Brad, somewhere on the net I came across a layout for a 5G9 that had a bunch of extra jazz like a sag control, a master volume, maybe some kind of power scaling deal -- it was a poor quality image, so I'm not sure what all is there.  It says "Brad" on it -- was this yours?  Did you ever build it?

[Willabe]

It could be.   

Early on I drew up a 5G9 with a bunch of Kevin O'Connor's circuits added, like power scaling, sag and his PPIMV. I might have posted it at the Power Scaling forum several years ago. I drew it up with Sch.

I never built it. Glad I didn't because it would have been a bear to wire up in the chassis I was going to use, in fact I think it would NOT have worked in it at all.


             Brad      

[Willabe]

Ok, tried another (brand new in box) NOS JAN Philips 5Y3, same voltages within ~2volts.

Also tried a NOS GE 5V4GA;

5V4GA; B+ pin 8, 398vdc

6V6; pin 3, 384vdc, 4, 349.2, K, 21.9vdc

Fender schemo for tweed Tremolux lists 395vdc at 1st B+ node with a 5U4GA.

Odd thing at 1st I was trying to read the dcv at pin 8 on the 5V4GA and I was using the regular pin meter probe and 1 of the heater wires sparked to the K sleeve, I think. I'm sure I saw it spark, saw it out of the corner of my eye and heard a pop through the speaker the 1 time and thought what the heck, then the 2nd time, a few seconds latter, as I was watching the tube, I saw it clearly and heard it again and I turned it off.

I shut it off instantly and tried again with a little spring hook probe and no problems.   



                      Brad           

[lego4040]

This time of year when humidity is at zero and that air is real dry I've encounted zaps touching metal and have had arcs jump out to the fingertip. Kinda like as a kid and you rub your feet on the carpet and touch a light switch. I want to make this as close as possible to the real deal and use the 5U4GA tube, I'll save my other pt for my next build. I want to make sure I get the right Mercury Mag. They don't show specs on site but I'm pretty sure its the FTTP/M, is that what your running

[Willabe]

This time of year when humidity is at zero and that air is real dry I've encounted zaps touching metal and have had arcs jump out to the fingertip.

But this was inside the tube in a vacuum.


                        Brad        

[lego4040]

My mistake, I thought it was coming from the bare point of probe to chassis as well. Was it only happening when you would put probe on and off or happening as you kept probe on?

[lego4040]

Bad tube? If you can return the tube then see if it happens with its replacement