5E3 Scratch Build

[Lonely Raven]

Howdy all!

I've been away for a bit. Health issues have kept me from doing much except going to work and back home to rest...

Anywho, I'm looking to build a 5E3 from scratch. I've had some transformers in a box for years now, and I've got a donor cabinet/chassis in the form of some 1X12 Fender transistor amp my Dad gave to me to gut out.

I've built many kits before, but I've never really scratch built anything but a BF Champ before. All the parts options are getting a bit overwhelming. Especially since I want to get parts on the high end side. I'm hoping you all can help me get the right stuff, and hopefully educate me along the way!

My ultimate goal for this 5E3 is to have that harmonically rich, complex overdrive, and touch sensitivity. I typically dial in an amp where I like it, and do the rest with the volume knob and picking. I figure a 5E3 is a good choice for this.


One of the first questions I have - I have some Solen Fast Caps 15uF 630v. Is the higher voltage rating going to be an issue?

Any other key components or design tweaks I should be looking at to obtain my goal?

Thanks in advance.

[Structo]

I think a couple things help the 5E3 become the amp it did.
The undersized output transformer, saturates early for that creamy tone.

The speaker, I'm not an expert but I imagine it breaks up soon.

For coupling caps, since there isn't that many I would be tempted to use something that is as close to the originals as possible.
Didn't the tweeds use the yellow molded Astons?

Anyway, I would probably splurge on the Sozo blue caps.

I hate seeing a tweed reproduction with orange drops or mallory 150's.

But if you are trying to save bucks, you can certainly use whatever you like.

No, I don't think using a high voltage cap hurts the tone, but it usually means a bigger physical size which may prove difficult to fit.

[Lonely Raven]

I think a couple things help the 5E3 become the amp it did.
The undersized output transformer, saturates early for that creamy tone.

The speaker, I'm not an expert but I imagine it breaks up soon.

For coupling caps, since there isn't that many I would be tempted to use something that is as close to the originals as possible.
Didn't the tweeds use the yellow molded Astons?

Anyway, I would probably splurge on the Sozo blue caps.

I hate seeing a tweed reproduction with orange drops or mallory 150's.

But if you are trying to save bucks, you can certainly use whatever you like.

No, I don't think using a high voltage cap hurts the tone, but it usually means a bigger physical size which may prove difficult to fit.

That's exactly the type of suggestions I'm looking for. I was looking at the Sozo, and I don't mind spending the $$. I also have a few Solen Fast Cap .1 @ 600 I could try.

Speakers I have a bunch of to try out. Mostly heavier, high wattage stuff, but I want to focus on the circuit first.

I'll have plenty of room for big caps, since I'm retrofitting this in a 1X12 (modern) chassis, and I make my own turret boards.

[Colossal]

Raven,

Good to see you back around. Hope you are doing well.

No harm at all in using the big 15uF 630V Solens. They will be great in your power supply and the extra voltage rating is a plus. You should get fast, tight bass response with them with maybe a little more perceived top end. The Blue Molded Sozos sound great, I'd recommend them. They are a little darker sounding than the Sozo Vintage mustards but have a nice, warm softness to them on the edges while retaining excellent clarity.

[Lonely Raven]

Alright, I'll test out some Sozo Blue Molded then. See how they compare to what I have in stock...which is (currently) Xicon, 715 OJ, Solen, and Mojo Dijon.

On a similar thread, how critical are resistors? I've got some Allen Bradly NOS from the 60's that I picked up at a garage sale, and I've got some of these DALE metal film 1% 1/2 watters.

http://www.tubedepot.com/r-cmf60.html

[Big Jim]

Raven,
I recently built a 5E3 with the Blue Sozos. I think you are definately on the right track. Everyone that has played this amp raves about the touch sensitivity and smooth, dark (in a good way) tone. I put mine in a laquered cab with a Weber 12A125 alnico speaker. It has quickly become my favorite amp ever.
Jim

[dave g]

Whatever you do, just remember to stick a 470k resistor on the grid of the phase splitter. You will not lose any gain or high end, and it will dramatically improve the distorted sound of the amp. Don't bother with the fixed bias PI ("Paul C mod" as some people call it) or any junk like that. Just add the 470k resistor.

This one resistor (and hell, use a 1/4 watt metal film if you want) will improve the tone of the amp far more dramatically than $50 worth of overpriced caps.

By the way, are the Xicon caps you have the MPPs? Because those are some really great caps...if I had a stash of Sozos laying around, I would probably trade them to you for some MPPs

[Phil_S]

470K as grid stopper or grid leak (to ground)?

[dave g]

470K as grid stopper or grid leak (to ground)?

Grid stopper, directly on the tube socket. Just make sure you put it after the 1M grid reference, not before

[vibratoking]

In what way does the 470k resistor improve the distortion? Can you elaborate more about this?

[dave g]

Merlinb posted an article about it here:

http://www.freewebs.com/valvewizard/cathodyne.html

It's at the bottom of the page under the heading, "Avoiding Unpleasant Overdrive Tones"

[Lonely Raven]

Merlinb posted an article about it here:

http://www.freewebs.com/valvewizard/cathodyne.html

It's at the bottom of the page under the heading, "Avoiding Unpleasant Overdrive Tones"

OK, I've read the article a couple times, but it went over my head still.

Where would I put this resistor on my 5E3? Could you possibly draw it for me?

[rp]

I read thru Merlin's article but I too am still not sure where this goes exactly. Below are 5E3 details, is it across the tube, if so from what pin to pin does it go?

[dave g]

I've attached a drawing showing where it should go on the layout.

[Lonely Raven]

Wow, that's it, huh? Thanks Dave! I'll make sure to try it out in my build!

I'm still waiting on parts. I hope to get started on this on Sunday.