AB763 Deluxe reverb clone - Ugly break up

[Jazz P Bass]

I , for one, am absolutely clueless where the OP is going with this thread.
It is all about "it sounds like this"
Voltage measurements, an oscilloscope on the output.
Something.
I posted way back of the fact that the tone controls have a huge influence on the preamp signal. (ie: which frequency clips first)
Turning the bass control to 10 on any Fender is going to clip those frequencies first.
And we all know how crappy "that" sounds
I submit that the amplifier is doing what it was intended to do.
Amplify a guitar signal.
Without concrete information, what more can be said?

[J M Fahey]

Hi el fela.
Please listen carefully to:
Fender Deluxe Reverb Reissue - YouTube
There are zillions of videos but this one should do.
1) to demo the Clean sound, he uses volume on 3
2) to show the beginning of crunch he uses 4
3) to show overdriven sounds, he uses 7.
All with sensible EQ, of course. Definitely not Bass 10 Treble 0 by any means.
4) he´s overdriving it with regular classic Strats and Teles, no powerful pickups, boosts , pedals, nothing special.
5) maybe a Deluxe is not what you need, sorry.
Anyway, you built an excellent amp, used a good speaker, it sounds like it should; if not what you were after, I´m sure *a lot* of Blues/Classic Rock/Country/Funky/Reggae/etc. Guitarists will be more than happy with it.
Or a Recording Studio.
No, no Metalists, Punks, etc. Not even with a MetalZone .

[Tom Phillips]

I'm tossing in another comment that your amp sounds normal for a DR. We are back to the comments of #3 & #4 of this thread.I think you were expecting something that a DR cannot do. In fact no classic fender blackface amp will sound good with the volume and bass on 10 and the treble on 0.

[Jazz P Bass]

A typical distortion, thrashy amp setting, with the guitar on bridge pickup, should not include bass tones.
They do not sound good distorted. (farty?)
Even the mids can get out of hand.
Marshall uses a 1uf cathode bypass cap for this explicit purpose. (as opposed to Fender 25uf)
Peavey Triumph type amps have a dedicated circuit to remove bass tones when you select the crunch channel.

[überfuzz]

I don't know whether to add something or not..? Forums wizes already chimed their wisdom.

Don't start tinkering before you record some action with your band, next time you rehears. My perception is that break up/distortion fades a bit in a band setting.

To me the amp sounds good. Maybe the guitar is kind of high in output? Did you play the amp in a band setting?

[Bruce / Mission Amps]

Wow... some really good comments about unrealistic expectations here!
Most novice and intermediate builders/players have a tendency to think you can build one or play a stock SF or BF Fender amp, reasonably loud, with the bass up past 4-5 .... it's not gonna happen and sound any good.
There's just too much bass and low mids. And a high volume setting with a 6V6 amp makes it worse!
Depending on the guitar (I don't care for a hot HB guitar with many *stock* Fender amps) most all the good players I've ever heard has the bass on SF or BF Fendery built amp, set at around 2.5 to 3 max, mid at 4-6 treble 5-6 & the volume around 4 to 5.
That just seems to be about the sweet spot for most players and that preamp with tone/section.

Play it loudly, keep the bass low... and that's no secret with gigging Fender amp users.
Well... those who are looking for a classic driven Fender amp sound.

[el_fela]

Wow, a lot of feedback!! I really apreciate it.

I agree the amp sounds quite fendery and it rocks.
Thanks to what you're telling me, I understand now that it's not supposed to sound good with every eq setting. It's a relief to know that.
Still, there is something funny going on with the bass mid/bass frecuencies, even with bass at 0 and treble at 10.
It's not as bad as I thought, I know, but there is something there. It doesnt sound like the demo on youtube. The bass starts to clip too early.
It doesnt show much on my recording, but when i use a dummy load and listen to the amp trough my headphones you can hear it clearly.
Specially the undertones, which might be causing the problem.
I'm going to record precisely that so you know waht I'm talking about.

Lead dress, bad layout, yeah, I know.
Oh, and I was using 4,7uf bypass caps at V2 and V4. Forgot to say that, sorry.

Voltage measurements, an oscilloscope on the output.
Something.
I posted way back of the fact that the tone controls have a huge influence on the preamp signal. (ie: which frequency clips first)

I will gladly upload some scope captures (software scope,thats all I got), at least for the record, so it might help someone else.
But I'm not an expert, and I need some hints regarding what to measure.

Thank you guys

Felipe

[J M Fahey]

when i use a dummy load and listen to the amp trough my headphones you can hear it clearly.

Well, don´t
Test tones, dummy loads and oscilloscopes are *great* for troubleshooting, but then you must plug a guitar and play.
Just like that.
Good luck, friend.

[jmaf]

..... I need some hints regarding what to measure.

The sample you posted initially sounds like square wave clipping by the end, IMO it's just overdrive but since you used bass 10 and treble 0 it sounds like Atari race car. If you want it cleaner, why not use a lesser gain tube for V1? Try a 12AU7 in there, it should be pretty clean then. Or remove those 4.7uF cathode bypass caps....

[J M Fahey]

why not use a lesser gain tube for V1? Try a 12AU7 in there, it should be pretty clean then. Or remove those 4.7uF cathode bypass caps....

Maybe .... but it wouldn´t be a Deluxe anymore , would it?
Why bother building one to begin with?
Face it, el fela does not like what a Deluxe Reverb does or sounds like. Simple as that.
No amount of tweaking will change that.

[jmaf]

Maybe .... but it wouldn´t be a Deluxe anymore , would it?
Why bother building one to begin with?
Face it, el fela does not like what a Deluxe Reverb does or sounds like. Simple as that.
No amount of tweaking will change that.

That's very true. And it's exactly how I think about this issue. You can't make a Twin sound like a JCM 800 and they're both great (series of)amps, each for a musical taste.

Edit: Of course, before sticking the soldering iron in there, changing to a 12AU7 would be an easy to reverse "mod".

[J M Fahey]

True.
But I still seem to see that rather than a preamp problem, we have a headroom/power amp one here.
I already PM'd el_fela suggesting 6V6 , with their early breakup, lovely for reasonable volume crunch in Rock and Blues amps, may not be the best for what he needs.
Maybe a new project with 2 or 4 6L6 would be an entirely different beast.
Since by sheer chance he lives just 2 hours away from my shop, I also offered him free access to my oscilloscope and whatever else he needs to check it, on some idle Weekend.
Although I anticipate the amp will perform as any other healthy Deluxe.
jm2c

[jmaf]

Since by sheer chance he lives just 2 hours away from my shop, I also offered him free access to my oscilloscope and whatever else he needs to check it, on some idle Weekend.

Nice that a fellow Porteño can find your help over there.

A cap job, without modifying anything, may help harden the power section....

[überfuzz]

...

A cap job, without modifying anything, may help harden the power section....

Care to elaborate..?

Have had thoughts of tightening one of my ab763 builds...

[jmaf]

Care to elaborate..?

Have had thoughts of tightening one of my ab763 builds...

This: http://aga.rru.com/Events/MM-DRRI-re...s/image033.jpg
( Source: Deluxe Reverb Reissue Rebuild )

If using a tube rectifier, add two 1n4007 diodes with the white band facing the plates of the rectifier to protect it.

And without changing a thing on the amp, replacing 40+ year old caps tend to tighten the bass response and gives the amp more definition.