Original 5E3 Info Please!

[Platefire]

I was doing a little research on the 5E3 wondering what the real DCV output loaded was before filter caps. The original schematics don't have any voltages. I found one statement on a forum post that said it was 350VDC?

Also does anybody have the specs on the the transformers. I know there are lots selling so called "5E3" transformers but I would like to know what the original spec was. Plate

[FYL]

The 5E3 - and other Fender amps from the same period - used a Triad 6452 PT. At 110V/60Hz mains, B+ was 380-0-380V unloaded with a highish 230R secondary DCR, leading to app. 350V loaded at C1 with a real 5Y3GT.

Measured unloaded & loaded voltages + specs of an actual '57 vintage 6452:
B+: 380-0-380V 230R, 100mA => 358VDC
H: 7V 0R45, 3A => 6V4
V: 5V5 0R26, 2A => 5V

Loaded voltages measured using a typical all-RCA period correct tube set (12AY7, 12AX7, 2x 6V6GT, 5Y3GT) and a vintage board fitted with recent elcos. B+ could be slightly lower with lossier caps, but still in the 350V range.

[HotBluePlates]

Check out the 5C3 Deluxe schematic. The 5D3 and 5E3 schematics do not have voltages listed.

It is not obvious, but the plate voltage at the output tubes is approximately 360vdc. The OT center-tap is fed from the rectifier output pin, and the first filter cap is connected to that point. The Fender schematic states voltages are +/-20%, so by that statement aything from 432v-288v is "within spec".

Realistically, the 360v number is very close to what it will be, and the +/-20% applies more to small bias voltages.

The Fender Transformer Conversion chart implies that most or all tweed Deluxes used the same PT.

Given FYL's unloaded numbers and DCR, I'd guess the "spec voltage" would be about 350-0-350, 100mA for the transformer or 320-330vac and slightly higher current.

Note the conversion chart (and most vendors' PTs) have only corresponding transformers for blackface models. The tweed Deluxe PT is definitely not the same as a later Deluxe PT.

[Platefire]

Thanks Guys! That helps and I really appreciate it. I built a 5E3 last year using a 325/325 70mA PT which was the Hammond P-T290AX. The voltage to OT was 319 and to plates was 314. The amp was suprisingly clean and loud. I am planning to building another 5E3's and I want to get it closer to original spec as possible. I will start looking for a slightly higher PT than the 290AX.

Don't know if you have ever read the "Modified Fender Tweed Deluxe" ECE 445-Senior Research Design(on the net)? It is a reasearch report where they took the 5E3 and sought to correct all the design flaws and possibly bring it up to modern standards. At some point I think they may have defeated what made the 5E3 famous (in which they admit in the report). Anyway the 5E3 Deluxe plus that I built last year was also my own twist to the circuit but this time I want replicate the same old circuit except for a few minor updates--two inputs(instead of four), screen resistors and grid stopper resistors, three conductor power cord, stanby switch and everything else original.  Plate 

[HotBluePlates]

The voltage to OT was 319 and to plates was 314. The amp was suprisingly clean and loud. I am planning to building another 5E3's and I want to get it closer to original spec as possible.

You want to fight with success? 

But seriously... what might you gain by having 35-40v more B+?

[Rev D]

 The one I built was a cheapy, I used a 270dx and 125e and I don't have any fancy tubes in it. I might try a older 5y3 in it and get a decent set of nos's just to hear how it sounds, but honestly even with the cheaper transformers it sounds darn nice. I did use decent board components in it. I'll tell you, I have the 12ay7 in it, but often I'll put the ax7 in V1 and then it'll get some darn nice rock tones. Dimed its just a little beast. My bandmates called it the little green monster cause of the paint on green bed liner I put on it.
 My point is, my other bandmate had his built with all the best including Mercury trans and to be honest they don't sound that far apart. Yeah his is a tad louder, but once they get above a half there's not much difference.
 The circuit sounds how it sounds and if you dig it its great, I get a little tired (and I'm not speaking of what your wanting to do) of hearing people doing this and that to change its sound. The point is why bother with a 5e3 if people want to go fixed bias or add this mod or that? I've had people say oh man, that doesn't have enough current, this and that ain't right, tell ya what I've rocked the amp for 6 hours a week in rehearsals for 4 years and never had a problem with it.
 Good luck with it, I'm sure you'll enjoy it, they're great amps and If I could only have one on a desert isle I can't think of a better one.

Regards,

D.

[Platefire]

Hi Rev D

Well yeah, the first one I built I moded it from original(see pixs). The one I'm considering now will be pretty much original except I don't go quite as far as some folks. I like a standby switch--which I don't think will change performance. I don't see any use in installing 4 inputs---I would just use two.
I would add the 1500 R grid stopper and 470 R screen resistor. I will never fork out enough funds to purchase a vintage 5E3, so if I'm going to hear what it operates like, I will have to re-create it pretty close to original.

[phsyconoodler]

Hey Plate,
   I've built quite a few 5E3's with the Hammond 290AX PT and they were never under 350v at the plates.It depends on the rectifier tube you used.I use only NOS 5Y3's now because they keep the voltage right around 350v.With a Sovtek 5Y3 the voltage climbed to 385v.
  I never use screen resistors as I feel they are a waste and they alter the tone slightly.A 6V6 doesn't need them at 350v.
The speaker is the most important thing in a 5E3.Weber's 125 is probably the closest to the original Jensen,but I've even used Celestions with great success.
  The key to getting the most from a 5E3 is using your guitar's volume pot.I leave them cranked to at least 7 and turn down for clean tones.But...I use a high-pass filter on the volume pot of the guitar to retain the highs as you turn down.
  It gives the most incredible clean tones you have ever heard that way.Many guys just write off the 5E3 as having no clean headroom,because when they turn down they lose the highs and it gets muddy.I often show up at a jam with the 5E3 and nothing else and get amazing cleans and dirt all night long.Guys come and ask me what amazing pedal am I using.I point to the amp,the guitar and the cable.No pedal buddy!

[Rev D]

 Yeah Plate, I did fudge and add a standby too. It just replaces the ground switch, but I went cheap and used a aluminum Hammond chassis (no faceplate, but it was for me and how hard is it to remember three knobs   ). I did use 4 inputs and really just play off the bright ones, but it is kinda neat to be able to jumper them and play with both volume knobs for a few different tones. Using 4 inputs you can even come out of the first channel through a effect and then into the next channel doing that you can turn down the level of the effect coming into the channel (which is probably redundant if it has a level control on the effect) while still having a channel clean. Course with the 5e3 the volume knobs are kinda active between the channels anyway, I think that's one of the most charming things about it. Anyway, good luck with it, they're a hoot.

Regards,

D.

[Platefire]

Phsyco

You da 5E3 Man! I'm hopen you will told me some 5E3 stuff:

1-As I recall, I used an ol used RCA 5Y3 on that 5E3. You recon that tube was faulty was the reason for my low plate voltage???

2-I hear ya, on the screen resistors. What do you think about replacing the 5K resistor in the power supply with a choke?  

3-I basicly want to build another 5E3 to get the sound that made it famous--like your getting. It will be a head and I hear you on matching it up with the right speaker. So do you have a schematic of your favorite 5E3 build?

4-Attahed is the schematic of the last 5E3 build, the channels were seprated and I had some cathode bypass cap/resistor switch going on on channel #2. I think the customer wanted more early breakup and it tended to be more loud and clean. I plan on this next one to go with the original 5E3 tone stack arrangement. I also plan to install the shared cathode resistor and bypass cap like the original also.

5-So I'm thinking I probably shouldn't update the circuit too much to obtain that original sound. What ya think? Plate

[phsyconoodler]

Plate,
  You can't use a choke and expect the original sound,it makes it too modern sounding.Smooth but too modern.
I use the schematic and layout from schematic heaven.Just like the original.
 A Weber 125A or 150 Alnico speaker sounds absolutely delicious.Ceramics sound too modern also.The woody tone is lost with ceramic speakers.
   I don't know why you got low plate voltages,but it could have been the rectifier tube or a wrong resistor value somewhere in the circuit.

[tubeswell]

According to my off-the-cuff memory the original 5E3 PT was rated (off 110VAC mains supply??) at:

325-0-325VAC @ "70mA" (*)
6.3VAC @ 2A (just enough for 2 x 6V6, 2 x 12A_7, and a 0.5A bulb)
5VAC @ 2A

and it was the same as the BFPR PT** (and OT). But don't ask me where I 'remembered' this from.

* Hmmm... I guess this assumes that the 6V6s would be conducting less than the full 360 deg cycle. I think that the rating on the PT was conservative. The fact that it was designed with a 110VAC mains  could explain why FYL's measured example would be quite a bit higher.

** listed as a 125P1B here http://www.unclespot.com/FenderXFMRs.html 

Meanwhile, Hammond rates their Tweed Deluxe PT at 81mA (325-0-325 loaded off 120VAC), see -  http://www.hammondmfg.com/pdf/EDB290AX.pdf, probably for a bit more of a reliability buffer

Weber makes theirs 100mA - http://taweber.powweb.com/store/022772sch.jpg,

According to Mercury magnetics its 380-0-380 off 120VAC, which is pretty much what FYL says

http://www.mercurymagnetics.com/images/transformers/schematics/PT/FTDP.pdf

Fraught with different opinions init?

[Platefire]

OK, Thanks! Yeah I'll just go with the original setup and probably same transformers I used last time(no choke). Now to make a parts list. Plate

[FYL]

and it was the same as the BFPR PT** (and OT).

Tweed amps used Triad iron, most BF's were fitted with Schumacher models. But both PT's were quite similar voltage- and current-wise and mechanically compatible.

I guess this assumes that the 6V6s would be conducting less than the full 360 deg cycle.

They don't: the SE3 PP works in deep class AB1, not class A.

[bnwitt]

I don't know how many 5E3 amps I have out there.  Around 30 or so.  All but a couple of them have chokes, screen resistors, Jensen reissue P12Q's and the Hoffman layout.  I have at least one that is part of the amp list in a local studio along with an original 5E3.  That one has been A/B'ed next to the original 5E3 numerous times and every time it has been the Hoffman 5E3 that has been laid down on the recordings due to it's superior tone and touch response.  The recording engineers love the Hoffman because it is quieter than a dead mouse.  That situation has generated more then one additional 5E3 amp sale for me.  I personally find the Hoffman 5E3 to be the amp I love to play the most.  Tone is an individual thing, but numerous individuals choosing one amp over another in a pristine listening environment tells me something.

The main reason I use a choke is to strengthen the power supply of the 5E3.  One of the biggest complaints regarding the original 5E3 circuit is "Farting" bass notes.  It has always amazed me that a cheap practice amp from the 50's obtained holy grail status with farting bass notes.  I find the choke eliminates that original problem the 5E3 suffered.  Google 5E3 and farting and you'll see lots of complaints about it.

The reason I use screen resistors is to extend tube life.  I don't find a major tone change with them or without them in the Hoffman 5E3 so to me they are worth using.  

I use the reissue Jensen Q's because they sound great.  I also like the Eminence Red Fang in the amp and have sold some of them with that speaker too.

In my opinion the 5E3 is a great circuit but the original amp had some short comings.  Namely a weak power supply, too much noise at idle and and a cheap Jensen R speaker.  I believe Doug Hoffman addressed two out of three of those issues with his 5E3 layout and even though my first couple of 5E3's were faithful to the Fender layout, I realized the Hoffman layout with the optional choke was the best sounding 5E3 to me and many others who have played the Hoffman version I build.

[phsyconoodler]

I've never used a choke in a 5E3 yet and I don't have noise issues either.I don't use hoffman's layouts either.It just takes some careful lead dress.
  I do like chokes in many amps but a 5E3 doesn't really need one to sound great.Not that they don't sound great with a choke,just different.That's what makes the world go round.

[bnwitt]

I don't use hoffman's layouts either.It just takes some careful lead dress.

That is one of the things about the hoffman layout.  Even if it is built with less than stellar lead dress, it is still very quiet.  I find the Fender 5E3 layout (as you suggest) takes more attention with lead dress to make it quiet.  The Hoffman layout when done with care is so quiet you can't tell the amp is on even at high volume settings without putting your ear near the speaker.  I can't say that about any Fender 5E3 I've ever worked on. I did work on a 5B3 one time that was close to that quiet.

  I do like chokes in many amps but a 5E3 doesn't really need one to sound great.Not that they don't sound great with a choke,just different.That's what makes the world go round.

Agreed on the viva la difference.  I think the choke no choke is dependant upon what kind of guitar and pickups one is using.  With a strat or tele I don't think the choke is needed.  With humbuckers however, I think it makes a very important difference.  I think a builder should try it both ways to see if it makes the amp better suited to his/her playing.  This is why I encourage builders to try any variance from original they want with the 5E3.  I've seen so many threads where coupling caps are changed, bypass caps are changed all in the effort to eliminate the farting bass of the 5E3.  When you do that, you are just limiting the frequencies making it to the power section.  I think that is handicapping the amps output.  A choke enables the amp to reproduce the low mids and basses from your guitar and there is nothing like a jumped channel 5E3 for in your chest mids and lows when a choke is added.  Man I love that tone.

[Platefire]

Well I never played over an original 5E3, even the one I made prior wasn't original. I think I will make it very close to original except just 2 inputs, better grounding scheme and standby switch. I don't think those variation will effect the original amp operation. That way I can see how the original 5E3 is performing and decide then rather I want to change it or not. Plate

[Platefire]

This is a good discussion on the 5E3. Good info wrapped up in this thread. Got a question---------has anybody wired up a successful effect loop to the 5E3. It's going to take pedals to get your effects through this amp---for a clear sound--driver pedals need to go though the guitar input and time base effects need to go though effects loops. Surely this has been done also? Plate