Ideas for tweaking a 5e3?

[CapnCrunch]

Hey all,

I've recently finished a Rocket and have been playing the snot out of it. It has caused me to play around with some tones and sounds that are fairly new to me. One the things that it has done has made me much more aware of the value of a great clean tone.

On that note, I hadn't played my first amp build (a straight up 5e3 clone with the exception of Brown deluxe tone control) in a while so I set it up and AB'd it with the Rocket. I was quickly reminded why I hadn't played the Deluxe in a while..... The boomy, flabby bass. However, set fairly clean, the tone of the 5e3 is nearly on par with the Rocket in a different way. I'm not a big u2 fan, but I instantly realized that a lot of the Edge's clean tone comes from his tweed amps, and not his AC30's.

Sorry for the long lead up, but what I would like to do is tweak my 5e3 so that it is more balanced tonally. I would like to keep its' basic character, but reduce the bass, so that it is not boomy with humbuckers. At the same time I don't want to ruin how it sounds with single coils. Can this be done with out a switching options? I know it will be a compromise, but I'd like to avoid switches if possible.

This is where I'm thinking of starting. I have some .022 uf and .047uf caps on hand, so I'm thinking of swapping .022's for the .1 coupling caps on v1 and v2. I've read on other forums that some people suggest swapping out all four .1uf caps for .047's. Anyway, it will only take a few minutes to swap coupling caps so I think I'll try it and see what happens. I don't think I want to add NFB, but I'd be open to playing with bypass caps and R values. I will need to order some other e-lytic cap values though

[billyz]

What speaker are you using ?

I have played 5e3's for over 30 years and the only ones with flabby bass had p12r speakers. Also the original OT is too weak . The best I found is a vintage Deluxe reverb OT coupled to a p12q. RCA 6v6 or True Tungsols 6v6's are the ticket. The Brimars are too bright and thin. JAN GE's are good, might try the new EH or ri tungsols.


I just reread your post. Boomy, none of mine we ever boomy. you might like the Brimars then. and yes , I use a 64 335 and 345, fat not boomy.

[Jana]

Replace the 25uf cap(s) on the first and/or second stages with a .68uf.

[CapnCrunch]

Billy Z,

I have run of the mill EH 6v6's in the amp. Can't afford the good stuff right now. This is built from Bruce Collins' Mission Amp kit and has Mercury PT and OT. The OT appears to be a standard "tweed deluxe" OT. I almost forgot, I'm running a Weber p12b 30 watt Blue Dog in the amp, and like it a lot. I don't think the speaker is contributing to the bass issue appreciably.

I don't know if I'm using the best words to describe what I'm hearing. Clean, the bass is not flabby or loose it is just overpronounced. With HB'ers and the amp really driven, the bass is not well defined. I know that is part of the "charm" of this amp but I'm looking for a way to get the amp to have a little flatter frequency response I guess.

Jana,

Are you referring to the cathode by-pass caps? I have 22uf 50v elytics in there now. Would you change out both of them? Would you mess with the 820 R or 1k5 resistor values, or just change the caps? Also, what are your thoughts on changing the values of the coupling caps?

Thanks

Dee

[Jana]

Yes, I am referring to the cathode bypass caps. Maybe bump the second stage resistor up to 2k7 as well if you try a .68uf cap there.

Going to a .022uf coupling cap isn't going to change things much.

I would fiddle with the bypass caps first.

As Billy Z mentioned, some bigger iron always works wonders for the low end. But that's bucks.

[CapnCrunch]

O.K.

I went through my components and found two 4.7uf 50v e-lytics and one 2.2uf 50v e-lytic. I have a few other values but they aren't in the ballpark. I am thinking of splitting the cathodes on v1, replacing the shared 820R resistor with two 1k5 resistors and bypassing each of those with a 4.7uf cap.

I think I'll try that first and then see if I want to swap the 2.2 for the 22uf I have bypassing the 1k5 on v2. I could also just swap both 22uf caps with a 4.7uf respectively. I'm not sure which makes the most sense.

I've read some posts elsewhere by Bruce Collins where he recommends splitting the cathodes on v1. I kind of understand why the reduction in value of the by-pass cap reduces the bass response, but I don't understand the benefit in splitting the cathodes and giving each it's own bias resistor and by-pass cap.

I pulled the chassis and I think I'll head out and heat up the iron.....

[CapnCrunch]

Well, I did what I said I was going to do above. I pulled the shared 820R bias resister for V1a&b and split the cathodes. I gave each cathode a 1k5 bias resistor and bypassed the half serving the normal channel with a 2.2 uf cap. I bypassed the resistor on the bright channel with a 4.7 uf cap. I played the amp with my tele and my Les Paul.

This is the first amp I've really tried to tweak. Wow. I have a lot of respect for those of you that venture off the beaten path. You really have to listen analytically and try to pick up on every little thing. I am sitting here trying to figure out how to describe the effect that this change had, and I don't think I can do it. Oh well, I'll start simple. This mod definitely reduced the bass, and I may be crazy but it seemed to make the amp considerably louder. I'm not sure if that is just because the mids are more present now and that's tricking my ear or what.

I was surprised that the the highs seemed kind of brittle in a black face sort of way. I never used to turn the treble down past 3/4. I ended up with the treble almost off after this mod. I played both channels to see if I could tell a big difference between the two. The normal channel with the 2.2uf cap seemed pretty lifeless. It was pretty dark, which is something I'm not familiar with in this amp. It just didn't have much life in it. The bright channel with the 4.7uf cap had more of everything. More bass but less then before, and it had some cool 3d swirling going on. The highs, however, don't sound like a tweed amp anymore.

It had a more aggressive driven tone with a very sharp high end bite to it. Another thing that I think was there before, but wasn't objectionable, was a particular type of distortion that is hard to describe. It's like it was separate and distinct from the familiar power tube distortion; kind of buzzy and harsh and going on kind of separate from the power tube drive. I'm guessing it is coming from the PI. After this mod, it jumped to the front. Like I said, it was in there before, but now it is really prominent and ratty sounding.

The other thing I didn't expect was how different the amp would feel. A lot of the familiar 5e3 sag disappeared. Over all, it sounded really good in the bright channel with the Les Paul. The Tele didn't like either channel. If I were going to dime the amp and only play the Les Paul through it, I'd keep it this way for a one trick Rock and Roll amp. Overall, I think it was more versatile the other way around. I may try some values between 4.7uf and 22uf to see if I can find a compromise I can live with, but I really missed the spongy clean tone the amp had before. If my descriptions make no sense, my aplologies. It's the first time I've actually listened so critically, and tried to describe what I heard. That's an eye (or ear) opener in itself

[billyz]

Maybe try the Stock 5e3 tone circuit. ie. use a .005 cap instead of .01 on the brown deluxe. the stock 5e3 will lose less mids . and have more gain left on tap.

[tubeswell]

.022uF coupling caps after V1 remove a lot of flab. I did this with a 5E3 I made a couple of years ago. Works much better than .1uF. To take boominess out with bypass caps, you have to go down to 2.2uF or 1uF, but I'd try the .022uF coupling caps first. Worked for me anyhow. YMMV

[CapnCrunch]

Tubeswell,

I returned the circuit to it's original state with the 22uf bypass cap and 820R shared bias resistor for v1. I then replaced the .1uf coupling caps for v1 with .022 caps.

Much better. It's not perfect but it's much closer. It sounds very close to the original except that the bass frequencies are amplified at about the same level as the treble. Before, I think the bass was amplified at roughly twice the level of the treble. It's interesting, though, that this mod also changes the feel of the amp. Not as much squishy sag. I'm going to to play it a while and then put it back stock and see which I prefer.

My theory is that the original circuit taxes the recto tube to produce the bloated bass. The result is that familiar sag even in the high end. By reducing the amount of bass, less is required of the recto and it can keep up better thus less sag. I'm probably full of S$%t but that's my theory.

Thanks