1969 Twin Reverb breaking up early?

[sunlapse]

Just picked up a 1969 Twin Reverb, freshly retubed, recapped and blackfaced. Sounded great in the shop where I couldn't try it out too loud, and of course it sounds great at home too. But it seems to be breaking up earlier than I was expecting. Even around 3-4 if I really dig into my ASAT Deluxe (JB in the bridge, '59 in the neck) I get some overdrive. Dimed obviously it will be pretty overdriven, and maybe not even quite as loud as I was expecting. Do I just have a high tolerance for loudness, or is something else at play here? Improperly biased? Speakers are either Black Widows or Scorpions, the owner wasn't completely sure as the speakers were unlabeled (I can take pics if need be.) Any ideas?

[JubileeMan 2555]

Really hard to tell. The fact that you're using humbucking pickups will add to the drive quite a bit.

Where did you get the work done? Do you have any gut shots you could share? There's always a chance someone modified the amp in the past and wasn't caught. Or, you could just have a better tolerance to volume.

[sunlapse]

I bought it modded so I'm not sure where the work was done, but I can check. Again, should be to blackface spec – which has a lower headroom than a silverface, no?

[EricPeterson]

I am surprised a silverface would breakup that early, was it blackfaced at some point by chance? EDIT I see it was blackfaced, that is not crazy then with humbuckers.

[RussB]

Sounds right to me

[sunlapse]

So I guess then the followup question is this: how much headroom do I have to gain by unmodding back to silverface? Enough to warrant spending on something that could be controlled with my volume knob?

[Baminated]

it's hit or miss with those amps, particularly with the output transformer quality. I'd get a Magnetic Components replacement OT. Not that high dollar an investment. The weber JBL clones would help with the headroom.

Also, if you have hotwound ceramic pickups, such will contribute to early breakup. Try lowering the PUPS for starters

[zzmoore]

To me, "Black Facing", is much more of a mod to the bias circuit and some deletion of parts that CBS added to cure their crappy lead dress issues, in their pursuit of more head-room. Some of that stuff killed the brilliance of the black face tone, but it should not slaughter the head-room. Silver Face to Black Face should not cause the amp to go off at 3 on the volume knob, regardless of hums or singles.
You have got something else going on. You need to think about power tubes, bias, speakers, phase inverter, NFB, etc. etc. Do you know who did the work to your amp.? Are you sure it was done right, or that it even has "new" tubes for that matter. There is A LOT to maintain and account for in a Twin of that age. It needs to be looked at by a competent tech. IMO, terms like cap job, bias, black-face, etc. get tossed around pretty nonchalantly.
Anyway.....not saying I solved your problems, just some things to think about.
Best

[sunlapse]

Thanks for the insight. I was thinking that I'd get it checked out by a tech in the area anyways just to confirm everything that's been given to me. It's really a brilliant sounding amp, I just may want to think about getting some stuff done to it to get a tad bit more headroom in the future

[Big White Tele]

Sounds like a Torres mod. Are all the caps orange? Any pics of the board?

[nickyjoe]

Some Twins with some speakers will break a little. I've had several Fenders over the years pretty much...they all were a bit different. That being said; 3-4 should be pretty loud & clean Look for a good fender tech. I get Twins for back line a lot & use my Zendrive for smooth overdrive and I usually run them around the same settings.

[vinniedv8]

If you're looking to tame the early-breakup a bit, drop a 5751 tube in the preamp section. Lower-gain than than the 12ax7. Should increase your clean headroom a bit.

[sunlapse]

Got it checked out by a tech tonight and it appears that the bias as a bit off on the power tubes. The power tubes were also a couple years old and unmatched, so I got a new set of JJs. The amp also has one of the older 80w power transformers rather than the 100w that Fender started using in the early 70s.

I'm also realizing that the Peavey Scorpion speakers in there are pretty inefficient (94.9dB) in comparison to other speakers that people seem to like in Twins which seem to be in the 99-102 dB range. Any recommendations for a good speaker, preferably neo magnet, that'll give me a good overdrive/distorted tone as well as cleans? Eminence Lil' Texas perhaps?

[Baminated]

Yup, I knew it had something to do w/the OT

Get one a these !
http://www.classictone.net/40-18012.html

THing that's weird is the 4ohm tap - so you'll have to have two 8Ω speakers ( I THINK ?? )

These are awesome OT's - I have one in my Superbass clone, and it sounds gorgeous

Look into the Weber ceramic JBL D120 clones. Not sure of what neos can get good OD tones

[Tone Meister]

Originally Posted by sunlapse

...The amp also has one of the older 80w power transformers rather than the 100w that Fender started using in the early 70s...

Originally Posted by Baminated

Yup, I knew it had something to do w/the OT

He mentions the power tranny but not the OT. Personally I'd prefer the 80 watter over the 100 watt version for that amp.

Originally Posted by sunlapse

...I'm also realizing that the Peavey Scorpion speakers in there are pretty inefficient (94.9dB) in comparison to other speakers that people seem to like in Twins which seem to be in the 99-102 dB range. Any recommendations for a good speaker, preferably neo magnet, that'll give me a good overdrive/distorted tone as well as cleans? Eminence Lil' Texas perhaps?

Any speakers you choose will be an improvement over the Scorpions. Consider a pair WGS G12C for classic Fender. At 75 watts each they should be just right to handle that amp when it's tuned up.