AB763 Deluxe reverb clone - Ugly break up

[el_fela]

Its my second build and I'm having the same problem i had on my first one.

I dont like the way it breaks up. I never played an original deluxe reverb, so I'm not sure how it's supposed to sound.

So I made a recording with volume at about 5, treble 0 and bass 10.
You can listen to it here: ab 763 deluxe reverb distortion.mp3 - 0.99MB

It would be of great if someone could share with me a recording of a true deluxe reverb with the same settings.

I made a lot of tests to find the problem. The most significant of them consisted on listening to the signal coming from the PI with and without the power tubes installed:
When the power tubes are installed, there is some harsh distortion present at the PI's output, but without them its not there.

Please share a recording with me! Thanks!

Felipe

[cminor9]

I can't play that sound on my iPad. There are a lot of good videos on YouTube. That might give you a good idea of what they sound like.

[Jazz P Bass]

Why do you have the treble on zero & the bass on ten?

[Tom Phillips]

Why do you have the treble on zero & the bass on ten?

That's a good question and a red flag that something is wrong with the amp/speaker or you are expecting a sound much different from a DR.
Is there any chance that you can find a real DR to audition?

[el_fela]

well, there are no deluxe reverbs in any musci store in my city, and i dont know anyone who owns one.... but its good to know that is not the way a DR sounds hehe. thanks for your reply tom.

[Raybob]

I own a 68 DR but there's no way I'd record a sample with treble on zero & bass on ten.

My Tube-Tone Deluxe sounds basically identical to my 68 Fender.

[MWJB]

El Fela go to Fender.com & save a copy of the 65 Deluxe Reverb schematic, set as per the Wattage test & compare dc & AC voltages, you probably won't match volt for volt but look for similar proportions.

Any pics of the build, schematics just show how everything connects electronically....but, how everything connects physically has a bearing on performance too (what I'm saying is that you need a hell of a lot of luck to build a good example JUST by copying the schem & layout - google chassis shots of the BF Deluxes and try and spot any areas in which yours differs).

[el_fela]

hi

Why do you have the treble on zero & the bass on ten?

Well, I did that just to emphasize the problem im having. The clean sounds are OK, and the mid/treble break up much later on the volume scale.

[Jazz P Bass]

You have to understand these Fender amps.
With a 100mv sine wave at the input & all controls at 12:00, you will observe, as you sweep the frequency, that the bass freq will clip long before the treble freq.
Play the amp with the bass & mid control on zero & the treble & volume maxed..
How does that sound.
Now bring up the bass until it starts to sound farty.
That is the bass clipping.
Back it off & play it.
Now bring up the mids.
Same thing. Bring it up & then back it off.

[el_fela]

All voltages are -+ 10 within range as per fender schematic.
With treble at max, bass at 0 and volume at 6 (I cant set it louder here at my apartment) there is much less distortin.

Tried changing all tubes. Also I pulled all unused tubes for testing.

It seems that the distortion/noise comes from the PI or the power amp circuit.

Today I reduced the value of the coupling caps feeding the power tubes. I thought the distortion was better, but then i realized that it was still there, but the the low frecuencies were gone and icouldnt hear it so well.

[cminor9]

I'd listen to that clip and try to offer help, but I don't know how to use that page you linked to. I hate those file sharing pages. Soundcloud is much better and doesn't try to trick me into downloading russian crapware. This forum supports direct mp3 uploads, so you could just upload the mp3 file. I think I am not the only one who is utterly confounded by those sites.

My most recent build is a deluxe reverb, which came out perfectly, so I still have deluxe reverb on the brain.

[MWJB]

Why the extreme tone pot settings?

We are trying to carry out a diagnostic exercise on your amp, the conditions of the test are laid out on the schem. Follow them. Observe pot & switch settings.

Voltages being +/- 10v doesn't tell us much, please list dc voltage at idle for power tubes pins 3, 4 & 5 & plates & cathodes for preamp tubes. Pulling out unused tubes will give unrealistic readings, the amp should have all the tubes installed for the test conditions.

Deluxe reverbs work fine with 0.1uf coupling caps at the PI.

Other than specifying the voltages a look at the amp might be illuminating?

[Raybob]

hi

Well, I did that just to emphasize the problem im having. The clean sounds are OK, and the mid/treble break up much later on the volume scale.

If it's just the 'bass' range that you have the problem with, you can change the first stage filter caps to 22uF instead of 16uF. That will tighten up the bass.

[el_fela]

I'd listen to that clip and try to offer help, but I don't know how to use that page you linked to. I hate those file sharing pages. Soundcloud is much better and doesn't try to trick me into downloading russian crapware. This forum supports direct mp3 uploads, so you could just upload the mp3 file. I think I am not the only one who is utterly confounded by those sites.

yep that site is not cool... here a new upload:


***EDIT****
http://soundcloud.com/el_fela/ab763-...b-ugly/s-YRoy5



I will post pics as soon as I get a USB to micro USB cable.

Why the extreme tone pot settings?

I'd like to listen to the way the bass clips on a deluxe reverb, so I can tell if what I´m doing is working or not. Im so used to this distorting sound that I started thinking it was normal...

All voltages are very close to the ones shown at the schematic, with all tubes installed

B+ = 412
POWER TUBES:
pin 3: -34
pin 4: 409
pin 5: 410

V1
pin1 164
pin2 0
pin3 1.36
pin6 179
pin7 0
pin8 1.42

V2

pin1 163
pin2 0
pin3 1.39
pin6 166
pin7 0
pin8 1.42

V3
pin1-6 407
pin2 0
pin7 0
pin3-8 9

V4
pin1 173
pin2 0
pin6 170
pin7 0
pin3-8 1.43

V5
pin1 338
pin2 16
pin3 0
pin6 324
pin7 -16
pin8 0

V6

pin1 178
pin2 22
pin6 168
pin7 24
pin3-8 70

[el_fela]

If it's just the 'bass' range that you have the problem with, you can change the first stage filter caps to 22uF instead of 16uF. That will tighten up the bass.

I cant tell the difference in tone