Super Reverb AB763 tube questions

[scp]

Hi:

My amp is a '66 Super Reverb, AB763. I'm wondering:

1. If I replace the 12ax7 in V1 with a 5751 or 12at7, will I be able to crank the amp up and get power tube distortion at lower volumes?

2. If yes, can I do the same in V2?

3. If I can replace the TAD 6L6WGC power tubes with KT66s? TubeAmpDoctor.com says yes. Lord Valve says no, it will draw too much from the transformer and damage it. Can anyone resolve the apparent conflict?

4. If I can do it, what tonal differences can I expect?

This is the first time I've been on this site and don't know when I'll make it back, so if you want to reply to scp@posnerlaw.com, I'd be obliged.

Thanks!

[Bruce / Mission Amps]

Originally Posted by scp

Hi:

My amp is a '66 Super Reverb, AB763. I'm wondering:

1. If I replace the 12ax7 in V1 with a 5751 or 12at7, will I be able to crank the amp up and get power tube distortion at lower volumes?

NO, it takes more preamp distortion with higher gain to do that.

Originally Posted by scp

2. If yes, can I do the same in V2?

NO, it takes more preamp distortion with higher gain to do that.

Originally Posted by scp

3. If I can replace the TAD 6L6WGC power tubes with KT66s? TubeAmpDoctor.com says yes. Lord Valve says no, it will draw too much from the transformer and damage it. Can anyone resolve the apparent conflict?

Hmmm not sure, but I bet the old Schumacher PT can take it.
That would only be another 700ma to 800ma of 6.3v filament current.
I've know players that have run two EL34s in those amps for years and that's even a bit more load then the KT66s.

Originally Posted by scp

4. If I can do it, what tonal differences can I expect?

A little less total clean power with a slight warmer sound and some slightly different power tube/overdrive, squeezed tone. I think it would sound pretty good even if the SR output tranny is a little bit of a mismatch for KT66s.

Originally Posted by scp

This is the first time I've been on this site and don't know when I'll make it back, so if you want to reply to scp@posnerlaw.com, I'd be obliged.

Thanks!

I know you are new but many wouldn't bother answering questions here which require a personal response to your private email unless asked in a personal email to us, so why don't you just plan on coming back and joining the group....
Why?..... Most of us old timers respond here so that the many many other participants read our comments for their own general info too.

[scp]

Thanks, Bruce. I understand what you're saying, but maybe I didn't make the question clear enough:

With a 12ax7, the amp begins to break up at a volume setting of 6, and the breakup occurs as the volume level increases. But that volume level is awfully loud in small clubs.

What I was thinking is that with a lower gain pre-amp tube, I might be able to crank the volume to 10, maxing out the power tubes and getting more power tube distortion (and less pre-amp tube distortion), and the perceived volume would not be as great.

Not possible?

[Chuck H]

If you re read Bruce's post you may "get" it. The preamp drives the power amp. Whatever level that takes. If you lower preamp gain in any way this will decrease your ability to make the preamp drive the power tubes into overdrive. So if the amp is currently too loud at 6, with the lower gain preamp the amp will be "cleaner" at 6 and still too loud by the time you get into overdrive at 10. Nothing you do to the preamp will make the power tubes overdive at a lower volume. And if anyone tells you different they are either ignorant or lying.

There are alot of things you CAN do to make the amp quieter when overdriven. A less efficient speaker can help alot. Maybe plug into a lower efficiency 1x12 cab. Or get a pair of low efficiency 10's that can handle the watts and load them in the combo. Leave the other two 10's in the cab unused. That way your speakers are less efficient AND your moving less air. Reduced screen voltage and a rebias can help. As was mentioned with the kt66 idea, tubes that break up sooner will help. Groove tubes used to match tubes according to their breakup character. I don't know if they still do that under the new Fender management. But a pair of low # Groove tubes and a rebias would give you more breakup at slightly lower volume.

Chuck

[scp]

Thanks!

[Rick Erickson]

Or you could just get a TS-808 Tube Screamer, or some flavor-of-the-week boutique distortion pedal. This way you can set the amp to whatever volume you need and always get the same amount of breakup at that level when you engage the pedal. Use two tube screamers and you can get three levels of distortion and clean too. I see no reason to stress a Super Reverb with KT66 tubes. If it is working correctly it should be plenty clean and loud as it is.

BTW - The Super Reverb wants to see a Two Ohm load. I don't know of any suitable 1-12 cabs that meet this spec.

RE

[Bruce / Mission Amps]

For that extra kick in the pants....
another really decent sounding, low cost pedal is the Bad Monkey.
Set up for just a few extra dBs of gain, really turns a SF or BF Fender Reverb anything amp into a terrific sounding setup.

Check this out:

http://www.youtube.com/watch?v=7LOWP...eature=related

[scp]

Actually, what I've using is one of the Boss '59 bassman pedals, because it gives a little extra kick at low volumes without coloring the sound unless I want it to.

If I were to buy another pedal, I'd look for one that could add a slight sawtooth edge to the otherwise smooth sound of the Super. It's a pretty subtle thing: The best example I can think of is that sometimes SRV would grab the strings high on the neck and slide down; and instead of sounding like guitar strings, it would sound like a ricochet, and it wasn't done by scraping the pick. It's a minor item in his repetoire, but I've never been able to figure out how he did that. It's almost as though a sine wave, examined closely enough, has a subtle sawtooth configuration. Any ideas?

Anyway, Bruce, I'll go to the youtube site and check out the Bad Monkey. Thanks again.

[Rick Erickson]

[sometimes SRV would grab the strings high on the neck and slide down; and instead of sounding like guitar strings, it would sound like a ricochet]

From the videos I've seen of SRV, he usually wasn't anywhere near his pedals when he would do that. It's more likely a little echo and a lot of technique. I'm not a SRV fanatic though so this is just a guess on my part.

RE

[scp]

I'm not an SRV fanatic, either. My taste runs more to John McLaughlin and Joe Pass. But I'd love to know how he did that one thing, and it has to do with the tone he was getting. At first I thought it was delay-related, too. But it's not.

[Chuck H]

Stevie did that trick with both clean and distorted tones. It's all technique. Roll back the tone knob a little and fret the E and B strings at the 12th fret with your ring finger. Use your middle and index fingers to mute the other strings. Hit more than just the E and B strings when you pick. The added percussion from the muted strings is key. Slide down just as soon as your pick leaves the strings. Easy peezy. Once you get the idea you can experiment with different chords aslo.

The trick is the added percussion from the tone knob rolled back and the muted strings. And timing of course.

Chuck

[scp]

Thanks, Chuck. I've been trying similar approaches but haven't quite gotten there, yet. I'll give yours a shot.

[Chuck H]

Cool. Anyone know how to do that Billy Gibbons thing in Nationwide.

dooOO wakita wakita wak wak wak.... I'd love to do that one.

Chuck

[scp]

Hi, Chuck:

Tried the technique. Haven't gotten it down yet but developed a blister on a part of my pinky I've never used before. It's closer than other techniques I've tried, but there's something about the sound that SRV got as he slid down the strings that had nothing to do with percussion--an edgy whine that made the ricochet come alive.

Also listened to the Bad Monkey. Didn't care for it. Like so many pedals, it seems to saturate the signal with its own sound and I didn't hear the character of the guitar.

Another question, for anyone who cares to answer: I've got a Two-Rock, one of the prototypes that K&M experimented with while moving from the Opal to the Custom. Dumble-style circuitry, including adjustable gain and EQ inside the amp to voice the lead channel. Recently it seems to me that the amp has been losing treble response. Maybe it's just that I recently got the Super Reverb and am comparing them. But if I am losing treble response, I'd like to know the possible causes. For example, could one of my pre-amp tubes be giving out? The power tubes? The transformer? Any insight would be appreciated.

[Chuck H]

Most Two Rock amps are really straight foreward. As a consequence (or result) different tubes can make a bigger than average difference in the overall EQ of the tone. Definitely experiment with the first preamp tube and power tubes. Most Two Rock amps can generate a good amount of gain so microphonics can be a problem. Try a NOS RCA gray plate 12ax7 in the first preamp socket. I do pretty well with those. Good top end, very good tone and about one in 5 is a little too microphonic for the first slot in higher gain amps. A really great tube overall. I haven't experimented much with recent power tubes so I can't make a recomendation.

You might also try plugging your Two Rock into your Super reverb cabinet for an honest comparison. Speakers can make a huge difference.

One thing about the SRV thing is that he had thick, heavily calloused fingers. That will make a difference in tone that YOU can't recreate. There are some really good players that do that same "trick" and it always sounds thinner and more ordinary than when Stevie did it. His touch was very individual and so was his guitar. The one he called "#1". When he first tried it out he said that he had to have it because "it sounds like wood". Stevie had a very woody, reedy solo tone both clean and dirty. I didn't always like his tone. But it's hard to separate good tone from good playing sometimes. Point is, to make it just like he did it all things would have to be equal.

Chuck


Chuck

[ahamay79]

My fave is a Menatone "Bluecollar",older model, handwired, with the "skinny guy" on the graphic.

[Analog Assassin]

Originally Posted by Chuck H

Cool. Anyone know how to do that Billy Gibbons thing in Nationwide.

dooOO wakita wakita wak wak wak.... I'd love to do that one.

Chuck

I'm pretty sure he's pushing his string up against the pickup's polepiece.

[Chuck H]

Cool. Thats sounds like it could be it. Unfortunately I don't have a guitar with a neck humbucker right now to try it properly. But I'll try what I have and see how it goes.

Chuck