New Poster, New Amp: OTR-120

[Les Paul Lover]

The transformers might be old surplus from the late 70s early 80s.


@5810 - I've change electrolytic in a 15yo DVD player after it failed. It was a Panasonic cap (Panasonic DVD player too), so not a crap cap - like everything else, they can fail anytime.

I think I need to replace the caps on my AD15 though. I get a high gain high volume squeal I've noticed recently. Nothing I notice at the volumes I usually play at though.

[fiveightandten]

Well, woke up this monin' and did the po' boy mess around as a last resort type stuff. De-Oxit all sorts of contacts, re-swapped preamp tubes, tighten a couple things then turned it on and after a few hours still no "whoosh." In fact, running pretty quiet, almost creeping me out. Dimed the treble/presence too, no oscillation, wierd. Keeping my fingers crossed.

Also got to the hardware store for m5/6 screws. No square nut to faux weld in though, guess I'll have to order that online or try another hardware spot. Thanks for all the assistance!


I can say after a few more hours of playing I think I'll eventually order a pair of G12-65's and ditch the vintage 30's. It already sounds good, they're solid and loud speakers, but they keep it so I won't go past "5" on the treble knob, the less efficient darker speakers change the feel a bit, allow wider knob twiddlin', and are my thing for these kind of big iron amps.


Oh, the writing on the PCB seemed to say "NLOL DRIVE"...no idea, not a signature though. And, to me, compared to every other part of the amp the transformers still look like they themselves sat in a moldy basement before being put on the amp. Even the wire on them has that olive dark tint to all the colors which I don't recall seeing on my other 90's era amps. Seems a bit fishy, like they were used/scrap, lol. But, I guess maybe that's how they looked.

Interesting. I've never experienced an oscillation from dirty contacts, but that's great that it seems to be resolved. Nice job!

The transformers could be older irons that were sitting for a while. The amp does have a 70's PCB, so clearly they had older parts kicking around in stock. The 70's irons are nicer than what was put in the 90's heads, so it's not a bad thing if they're older.

The brightness you're experiencing could very well be the KT77's, as opposed to the speakers. I think those have a more strident top end than the EL-34's the amp was designed with. Also, it's worth mentioning that if you're playing the amp with the master volume below full, it will sound like a shell of itself. Crank the master up full and use the gain knob to dial in the grit you want. That'll show you how the amp is supposed to sound.

It's also worth double checking the speakers to make sure they're wired in phase. I guess what I'm saying is I've never heard someone complain about one of these being too bright. The complaint is usually that they're too dark. The OTR is brighter than an OR-80/120. But it's still dark in the great scheme of things.

The tone stack is a Baxandall style and much different than your typical FMV. It's *not* a regular tone stack without a mid knob. Lower treble and bass settings mean more midrange. Higher treble and bass yields a more scooped sound. Dial in accordingly and compensate with the FAC and presence knob. As you've likely already noticed, the amp covers a LOT of sonic ground with the seemingly simple controls.

[fiveightandten]

The transformers might be old surplus from the late 70s early 80s.


@5810 - I've change electrolytic in a 15yo DVD player after it failed. It as a Panasonic cap (Panasonic DVD player too), so not a cheap cap - like everything else, they can fail anytime.

I think I need to replace the caps on my AD15 though. I get a high gain high volume squeal I've noticed recently. Nothing I notice at the volumes I usually play at though.

15 year old DVD player maintenance? That's the labor of love.

Re-capping is a good idea. I just figured I'd provide a data point, as it's a big bill to stomach from the tech when you just bought the amp and have to spend money trouble shooting another problem as well.

Maybe I'll get around to recapping my 90's head at some point. But for now they're still going strong!

-Nick

[Phlowen]

That's a beauty!

I like your screen name even more though!

[deytookerjaabs]

Thanks fellas!


I scoped out some pics of older amp chassis plus their innards and along with the little markings/lettering/etc on top these transformers sure look matching to some of the older ones. Again, especially that trademark ugly 70's-eque tint to the wire...and the wire isn't dirty, that's just how it looks That's kind of neat.


I've got a long history with vintage 30's, did the same to swap them out of a blackstar artisan 30 and a germino club 40...both times I was much happier with the G12-65 and thought the top end was well tamed but more than that there was an increased "punchiness" (for lack of better terms) to single note lines, hard to explain. I could swap some real EL34's in there too at some point. Speakers appear to be wired properly, parallel 16ohm speakers so 8 ohm load, + to +, - to -, real clean solder job on the speakers too.

[bclaire]

Oh, the writing on the PCB seemed to say "NLOL DRIVE"...no idea, not a signature though. And, to me, compared to every other part of the amp the transformers still look like they themselves sat in a moldy basement before being put on the amp. Even the wire on them has that olive dark tint to all the colors which I don't recall seeing on my other 90's era amps. Seems a bit fishy, like they were used/scrap, lol. But, I guess maybe that's how they looked.

Can you get a clearer shot of that writing? Could it be Noel, referring to Noel Gallagher?

[Les Paul Lover]

Oh, the writing on the PCB seemed to say "NLOL DRIVE"...no idea, not a signature though. And, to me, compared to every other part of the amp the transformers still look like they themselves sat in a moldy basement before being put on the amp. Even the wire on them has that olive dark tint to all the colors which I don't recall seeing on my other 90's era amps. Seems a bit fishy, like they were used/scrap, lol. But, I guess maybe that's how they looked.

Can you get a clearer shot of that writing? Could it be Noel, referring to Noel Gallagher?

Good thinking!!!
So the OTR is an OR tweaked to hit requirements, that would make a lot of sense.

[Les Paul Lover]

The transformers might be old surplus from the late 70s early 80s.


@5810 - I've change electrolytic in a 15yo DVD player after it failed. It as a Panasonic cap (Panasonic DVD player too), so not a cheap cap - like everything else, they can fail anytime.

I think I need to replace the caps on my AD15 though. I get a high gain high volume squeal I've noticed recently. Nothing I notice at the volumes I usually play at though.

15 year old DVD player maintenance? That's the labor of love.

Re-capping is a good idea. I just figured I'd provide a data point, as it's a big bill to stomach from the tech when you just bought the amp and have to spend money trouble shooting another problem as well.

Maybe I'll get around to recapping my 90's head at some point. But for now they're still going strong!

-Nick

Tell me about it..... a month later the 15yo tv I used it with died.... got new tv.... newly fixed DVD player doesn't go on it.... modern tv's have no SCART plugs......

I just hate throwing stuff away if there's a chance I can fix it.....

[deytookerjaabs]

Here's the writing:




Eh, looks like it was written with a crayon. To me I still get NLOL DRIVE, huh.

[Jarkko Mattheiszen]

Just noticed this thread now, I’m the guy from the other thread mentioned earlier. I’ve got the same signature, always thought it was N/O/Drive. I’ve got the same oscillation with treble cranked, but to be honest, it’s so bright at the oscillating settings I haven’t even bothered with it even though it would be a pretty easy fix.

The schematic from mine differs quite a bit from the production run OTR, and I gathered the differences here if you want to compare: https://docs.google.com/a/taintedstudio ... sp=sharing

Cool to see another one of these, as mine is the only weird one I’ve been able to find until now! I’ve been on the fence of selling it, as I’m a studio owner and could use a classic clean amp in there, but I actually finally got to play the OTR myself with a band a couple of weeks ago, and man, it’s an incredible amp! Just perfect for dirty, mid-heavy rock tones!

[deytookerjaabs]

Just noticed this thread now, I’m the guy from the other thread mentioned earlier. I’ve got the same signature, always thought it was N/O/Drive. I’ve got the same oscillation with treble cranked, but to be honest, it’s so bright at the oscillating settings I haven’t even bothered with it even though it would be a pretty easy fix.

The schematic from mine differs quite a bit from the production run OTR, and I gathered the differences here if you want to compare: https://docs.google.com/a/taintedstudio ... sp=sharing

Cool to see another one of these, as mine is the only weird one I’ve been able to find until now! I’ve been on the fence of selling it, as I’m a studio owner and could use a classic clean amp in there, but I actually finally got to play the OTR myself with a band a couple of weeks ago, and man, it’s an incredible amp! Just perfect for dirty, mid-heavy rock tones!

Thanks for the info, I just saw your post for the first time! I've been riding this amp pretty hard and have to say it might be my favorite amp I've ever owned. Only complaint...maybe a wee bit more clean headroom but there's still a good amount there to hang just fine.

That FAC knob, and getting to twiddle (which I don't do very much) the other knobs in between setting that foundation feel is really something else. Some rooms are bright/sterile, some hollow/fat, and that knob kind of lets you tweak the feel so you're comfortable or at least countering crappy acoustics. Whereas, other amps I'll be stuck in some rooms thinking it goes from too muddy to too bright no matter how I tweak it.

When I sold my '63 6G2 Fender Princeton a while back I told some fellow players "Look at this" as I'd play through the 6G2 where it gets this little bit of smokey breakup and nice rounded cleans...then I'd get damn near the same sound from the big daddy OTR!

Yeah, just this right amount of clarity in the amp without being harsh, and the breakup doesn't go overbearingly square wave sounding which the Marshalls can do sometimes. I use the sucker for any type of music too.

In the future I'd like to get practically the same amp with a bit more portability too, maybe a vintage OR80/120 head w/a small but fitting cab. But, I don't mine lugging it around one bit, totally worth it.


Glad to see someone else has one!