1956 5E4-A Super

[heymymy]

Hey all,

I just picked up a '56 Super 5E4-A, with the 6V6 tubes.  I've heard that these amps run on the same voltages as their 5F4 Brothers
on the 6V6's... can you switch them out or would you have to modify, (which I don't want to do.)

Also, it still has the Selenium Rectifier in it, which scares me a little, so is it safe to leave in there or should I take it to a tech and have them put a Diode in there?

Thanks all!

[sluckey]

Are you saying you want to put 6L6s in it? You can, but why would you do that on an old vintage amp?

I'd leave the selenium in it too. Just don't lick it.

[heymymy]

I was asking about the 6L6's because I'm curious to see if it's the same as the 5F4 circuit, which it seems to be the same, except I think my PT (8160) is a lower voltage than the 66 version.  I actually don't really like 6L6's in general.

I won't lick the selenium, well, today i won't, but the weekend... who knows.

[heymymy]

Also, now that I'm looking at it, the ground wires are all soldered to the chassis, safe or should I move them to the PT bolts?

[navdave]

Don't mess with it you'll devalue the amp. If it aint broke?

[Danskman]

Hi!
Why on earth would you mod an oldtimer like this? If it is in its original state, I would just replace the mains cable with a new one, grounding the chassis, for security purpose.
If it was me, I would buy an amp kit, build it and mod it; you'll learn a lot about tube amps and improve your knowledge. But beware: this is a very addicting hobby and there's no cure for it (excepting an empty wallet   )
Best regards,
Danskman

[chocopower]

Some pics for the guts addicts?

 

[tommytornado]

You can try popping 6L6's in there for a test run, but I wouldn't do it and then run out and use the amp at a gig for 3 hours.  6L6's draw more current than 6V6's, so you run the risk of doing damage to the power transformer when putting 6L6's in an amp with a PT spec'd for 6V6's.  Also, unless someone added a bias pot, the only way to adjust the bias for the 6L6's would be to replace the bias resistor.. which might take trying several different values to get the bias right.  I've never heard a fixed bias amp with 6V6's sound good with 6L6's biased for 6V6's.

[bruno]

actually I think it's more likely that he'll damage current production 6V6s with that PT, then it is that he'll damage the PT with 6L6s, since I believe the PT used for that version  of the circuit is the same used for the 6L6 (5F4) version... So running a set of 6L6, might be just fine.

[Fresh_Start]

Short answer to original question:  NO

5e4a - bias voltage -32
Plate  - 380?

5F4 - bias voltage -40
Plate - 405?

Despite the slightly lower plate voltage, I would expect 6L6s to be biased way too hot with only -32 on the control grids.  Also, the output transformer primary should be near 8,500 (Deluxe) for 6V6s but only 4,000 (Super) for 6L6s.  Even if it weren't biased too hot, I don't think it would sound right.

+1 on not changing anything except for adding a 3-prong power cord.

Cheers,

Chip

[bruno]

several owners of 5e4-a have documented the original power and output triad transformers to be the same used in regular 5f4/5E5-a/5e7 circuits, so my guess is that the ot is indeed close to 6k primary, and there would definitely be no problem to install 6L6s in the amp, especially if you bias it accordingly, as a matter of fact, I believe the amp will be happier running 6L6s.

Changing output tubes, really doesn't mean he is changing the amp, now does it?

[Willabe]

Leo was a frugal man and would use what was in stock/on hand to get the unit out the door sometimes. There are/were also transitional models that are documented too. So just because maybe some 5F4/5E5/5E7 amps might have the tranny set you are refering to, does'nt mean that they all have that same set. See if you can read the code numbers on them and look them up, just to be sure/safe. Just my $0.02.

        Brad            

[HotBluePlates]

I just picked up a '56 Super 5E4-A, with the 6V6 tubes.  I've heard that these amps run on the same voltages as their 5F4 Brothers
on the 6V6's... can you switch them out or would you have to modify, (which I don't want to do.)

I'll second what Chip told ya; don't put 6L6's in there without modifying the (non-adjustable) fixed bias. You could adjust it if you lowered the series resistor in the bias circuit to increase the bias voltage at pin 5. The circuit is only "non-adjustable" because there is no adjustment pot to make it an easy change.

Also, now that I'm looking at it, the ground wires are all soldered to the chassis, safe or should I move them to the PT bolts?

I would strongly advise not touching these.

I used to own a '55 Tremolux. The filament wiring system used had a small wire running from 1 side of the filament at each tube socket to the chassis. What few people notice is that the pilot light holder assembly is also grounded to the chassis in a way that's hard to detect. If you get clever and rewire the heater circuit without undoing that ground at the pilot light, you'll likely burn up your filament winding.

Surprisingly, most of the time, you won't have any obvious hum due to the heater circuit in these amps.

So only fix what's actually broke.

[heymymy]

Ok, so basically I'm not going to touch anything inside the amp... the only thing I can't figure out tube wise, is I have heard that the PT AND OT for my 5E4 is the same as the 5F4 Super circuit, which would make me feel like the amp might be happier with 6L6's in it.

Is there a way for me to tell which transformer I have?  Or should i measure the plate voltage on the power tubes and see if it's running at around 380V, or if in fact it's running around 400+V? And would that give me an accurate answer.

I definately don't want to burn it up by using the wrong tube, but sure as anything I'm gonna use this thing, so three hours gigs and cranking it is non negotiable, I didn't buy to look at, that's for sure! 

[bluesbear]

I have to say this. I've been playing pro for 46 years and REALLY understand to urge to go out with extremely cool equipment. This amp more than qualifies. You will be happier if you build one just like it and use it instead. The pride of cool equipment pales next to the pride of your own build. I swear this is true. I still own a few great store-bought amps ('59 Les Paul GA-40, early Traynor, Music Man, Seymour Duncan, a couple old Fenders, etc) but I haven't used an amp I didn't build on a gig for 7 or 8 years. In fact, since I finished the amp for my bass player last fall, no one in my band ever uses store-bought. The other guitar player has been using his own builds for 20 years. The pride of build beats the pride of ownership every time... and it's not as hard as it looks. You've got all the help you'd ever need right here, the best in the world.
My point is that your Super is worth a fortune stock and it's only going up. Mess with it and you lose hundreds, maybe thousands of dollars. That's why my '59 Les Paul sits in my music room, not in a bar.
There are hundreds of guitar players here in Cincinnati. Probably 1/8 of them have really cool store-bought amps. I know of 4 that use amps they built themselves and another 20 or so that use amps we 4 built for them. Cool and exclusive; how can you beat that?
Just something to think about.
Dave

[heymymy]

Well, it's not totally untouched, there's been caps and resistors changed in it, and the speakers were changed to Weber P10Q's, but i see your point 100%.   I'm actually looking for some original 50's Jensen P10Q's so if anyone's selling, I'm paying.

I actually tried to build a 5F6A, last week and it was so frustrating, because i know enough to replace parts and not kill myself, but not enough to diagnose anything beyond measuring voltages.  And of course on my build everything lights up, barely any sound comes out,
and I don't show anything close to the right voltages, in fact, some have no voltage where it should be.  I did the schematic hi-lighter, I re wired the whole ENTIRE thing. Power up, same problem, barely any output.  But that's another topic.  

I did build a Metro Amp JTM45 which works perfect and sounds awesome, but it doesn't touch my 1970 JTM50.  I'm not of any knowledge to speak of, but my ears hear something different in old amps.  I don't think things like Victoria's sound like the real tweeds at all.   I just feel like the old amps "feel" different, like the amp and the guitar are singing to each other.   The boutique stuff I've heard and the clones all sound stiff and bright, or they just lack any character.  Truthfully the only reissue I've heard sound like the original was Marshall's 1974x 18watt, which I love.  

I totally get what your saying Bluesbear, and with the utmost respect, I just don't like my own builds as much.  I think I'm more happy knowing enough to maintain my amp and just standing back in awe of the fantastic craftsmanship when I turn up an old amp and play it everynight.   I don't even care who knows if it's real or clone, I just care how it sounds to me and makes me smile.

And I'll get pictures up soon after the holiday family madness is over seeing my in-laws all over the tri state area!

MERRY CHRISTMAS EVERYBODY!

[bluesbear]

Hey, I'm not an "old Fenders are sacred" purist. I've hacked my share. I just thought you should think of that angle before busting in. That being the case, replace the electrolytic caps, install a 3 prong cord, and let 'er rip! I wouldn't mess with the speakers, either. I've found 50's Jensens for amp restorations before. It's a crap shoot at best. Even NOS, the cones can be dry rotted.  I know from experience. If you like the Weber's (and it sounds like you do), they're probably better made than the Jensens were, anyway.
Enjoy,
Dave

[Willabe]

This is from Dave Funk's book "tube amp workshop". There's a list in the back that has many/most of the Fender amp trans set code #'s. Where he got them (and how true they are), book doesn't say.  

       Name       Model            PT         Choke         OT         Ohms        Tubes

       5F4          Super            8087        14684       45216       4            3 @ 12_7    2 @ 6L6      1 @ 5U4G

       5E5-a       Pro               6516        125C1A     1846         8            3 @ 12_7    2 @ 6L6GB  1 @ 5U4GA

       5E7         Bandmaster    67233      125C1A      N/A         2.6          3 @ 12_7    2 @ 6L6G    1 @ 5U4G    

       5E9-a      Tremolux        8160        14684       108         8             3 @ 12_7    2 @ 6V6GT   1 @ 5Y3GT  

       5G9        Tremolux         8160       14684       108          8            3 @ 12_7    2 @ 6V6GT    1 @ 5U4GB

The book shows schemos for 5E4-a Super and 5G9 Tremolux using the same tube type and count, so using the same PT would be an easy factory option.

All Super's before (5B4, 5C4, 5D4) the 5E4 and 5E4-a models and after (5F4, 6G4, 6G4-a, AA763, AB763, ect.) all used 6L6's. Only (from whats shown/listed) the 5E4 and 5E4-a used 6V6's.  
The 5G9 schemo has a factory written note > "Late 5E9-a models are similar to this (5G9) model". So late 5E9-a was a transitional model. This could be why the 5E9-a schemo (of early model?) he shows, has 5Y3 instead of the 5U4 rectifer tube that was used in the 5G9.

If your 5E4-a has a different OT code # than any of the ones listed here, post it and I will try to match it up for you to a model from his chart.

He has no code #'s listed for 5E4 & 5E4-a models, this is interesting IMO, maybe not many of these 2 models were made? If so, it make's it possibly more of a valueable model, which would only add to the advice given above as to not mess with it. The schemo's show tubes as >  3 @ 12_7    2 @ 6V6GT     1 @ 5U4GA   and shows 2 speakers (10's ?) were used in both models, if so, for a Fender it should be 4 ohms for OT secondary.

Hope this is helpfull to you.


        Brad        
  

      

[heymymy]

I'll look in the morning and see exactly what PT and OT are in mine. 
I'll also measure voltages and post and I'll get pics up, Lord willing...

So far, I know for sure all the caps on the board are newer, (mostly Dijon) and 50% of the resistors are NOS Allen Bradley's or Original.

Is there a way I can add a bias pot to the circuit that would be easily removable?  Does anyone have a layout?
I can see how to do it with a blackface style bias pot, but all I have on me are the tiny 50k Hoffman style, and
I'm not sure how to hook those up into this circuit.

[Willabe]

Is there a way I can add a bias pot to the circuit that would be easily removable?  Does anyone have a layout?
I can see how to do it with a blackface style bias pot, but all I have on me are the tiny 50k Hoffman style, and
I'm not sure how to hook those up into this circuit.

  Yes, look in Dougs library. Then go to >  servicing Fender amps > biasing the amp > (scroll down to) changing non adjustable fixed bias to adjustable fixed bias.

I belive Doug would solder one leg of the bias pot into one of the eyelets of the fender board, so it can be taken back out with no damage done to the amp. Should be no reason to take it back out, should be in there anyway IMO, though you still have the option to do so if need be.

         Brad              

[heymymy]

Ok, thanks for the link. 

I think I'm going to have to take it to a tech to have someone look it over, it seems to  be making a few weird hisses
and noises now when I touch my hand to the strings of the guitar, like there was a wire loose.  It's very quiet but i hear
it, and there's some weird noise when I turn the bass up on the amp.  Like a fuzz box would make.

[Willabe]

there's some weird noise when I turn the bass up on the amp.  Like a fuzz box would make.

Is it only when your turning the bass pot? It could be a dirty pot? Do you have any good pot cleaner? Easy to do. As to the other noises, could be same pot acting up, or maybe dirty tube socket and/or dirty pins on the tubes, maybe even dirty input jack contacts. Worth a try to clean them your self, tech's probably gonna have do that any way. Even if thats not it, you've elimanated some "checks" off of the problem list. Just a couple of thought's.

I'm sure others here will have more/better ideas than I do. 

If your 5E4-a has a different OT code # than any of the ones listed here, post it and I will try to match it up for you to a model from his chart.

If you post the trany code #'s, I'll try and look/match them up for you.


         Brad         

[heymymy]

I really appreciate you guys digging around for info on this amp for me, I waited a long time to get one of these, and I'm excited to
own it, but I also want to know how to maintain it and fix whatever might be wrong with it, but my knowledge is limited.
 
The transformer codes are:
Choke: 14631 (I think, it's pretty faded.)
OT: 1848
PT:  8160

While I was there I noticed the paper (?) where the code is stamped on the outside of the OT is cracked on one side, it looks pretty brittle, can anyone tell me what this is, and what to do about it? 

I also decided to check the voltages myself and they seems high to me, so here's what I got.
V1
PIN 1: 145v
PIN 3: 2.3v
PIN 6: 143v

V2
PIN 3: 1.5v
PIN 6: 292v
PIN 8: 191v

V3
PIN 1: 233v
PIN 3: 1.7v
PIN 6: 288v
PIN 8: 60v

V4 & V5
PIN 3: 425v
PIN 6: -36

Thanks for your help!

[Willabe]

Book lists,

       OT > 1848 > was used in, 5B4, 5C4, Super, 4 ohm. Schematic's show both models used 6L6 for OP tubes, and each had 2 speakers.

       PT >  8160 > was used in, 5E9-a, 5G9, Tremolux, 8 ohm. Tube type and count as listed in above post.

       Choke > 14631 > not listed, but 14684 was listed as being used in 5F4, Super. No other number for choke listed comes close.

So, if this info. is correct, the OT that was used in your amp, 5E4-a, was for -- 6L6's --, and the PT used was for -- 6V6's --.  

What rectifer tube is in your amp? 5Y3 or 5U4? Is there a paper tube chart (still) glued to the inside of the cabinet, can you read it?


          Brad                    

[heymymy]

Hey, that's weird... the Paper Chart is very clear... it says 5u4, 6V6, 6V6, 12AX7, 12AY7, and 12AY7 and it says 5E4

Is this a mistake? or did Fender just swap stuff around at the time?  It's definitely the original OT, either that or somebody changed it a LONG time ago. 

[Willabe]

No, it's probably not a mistake. Leo just had them use up the "old" paper tube charts before having new ones made for the "new" model. There are many Fender amps out there like this, some even have the tube numbers (changes) hand written in. It's common with old Fenders.

Are you going to try to clean the bass pot?


                      Brad             

     

[heymymy]

Wow, that's nuts that they just used all that stuff interchangeably.

The bass pot wasn't making the noise, it was more like a bad tone when the bass was all the way up, once I biased the power tubes and changed the preamp tubes it cleaned up, today I had it going for a while and no noises at all. sounding great!
Thanks!