Viper combo amp

[K_G_1]

I picked up a ADA Viper at a pawn shop about 8 years ago when I also bought my first electric guitar. I could find very little information about it, but the sound of it was awesome, so I bought it for a little over $200, thinking that I'd upgrade later. Long story short, I still have it and have yet to find anything for less than a grand that I like significantly better.  Clean tone is beautiful, and actually works quite well when amplifying my acoustic as well.  Red channel has a fantastic range of distorted sounds as well. 

Anyway, it's a great amp that looks mint, and everything on it works great, except the "varicab" cabinet emulation feature.  When I press the button for that feature, there is no sound except a very quiet hum.  Does anyone know if the cab emulation was any good? Is it something worth worrying about, or should I just continue to enjoy the amp as is?

[Harley Hexxe]

Hi K_G_1,

    First of all, welcome to the Depot :wave:

    Those amps are pretty rare, and the only person I can think of who could answer your question would be Kim. He had one but sold it to a friend of his. I think the Vari-cab would come in handy if you were recording with the amp, but it could also come in handy if you're mic'ing the amp in a live situation too. It all depends on your application.

  Harley 8)

[Iperfungus]

You can find the manual here:

http://adadepot.com/index.php?topic=129.0

or here:

http://adadepot.com/manuals/ADA-Snake-series-manual.pdf

Maybe there's some useful info about the Varicab...

[rnolan]

Hey K_G_1, Welcome to the depot 

(When I press the button for that feature, there is no sound except a very quiet hum.), there should still be sound coming from the internal speaker (unless you are in standby mode). There should also be signal at the record out jack (line level) and the Fx send jack, if not seems something's wrong in the Varicab circuit, definitely worth fixing  ADA cab emulation is very good. And, as far as I can see from the manual, it should make the very small combo seem ALLOT bigger  >:D

[Kim]

Hi and Welcome!   :wave:

When I had the Viper I left the VariCab on nearly all the time I played it.  The amp sounds good itself, but the WOW factor when the VariCab was engaged really surprises you.  Almost like when you bypass it, it feels like something is missing.....I didn't get to try any recording with the amp though.

Speaking of surprises, I was really impressed with the Crunch setting on the Green channel and the Drive all the way up.  Such a sweet singing sustain....

As for the question "Is it something worth worrying about, or should I just continue to enjoy the amp as is?"  the answer is YES.   ;)

[MarshallJMP]

Hey KG, first welcome the the ADAdepot 

As for the varicab, I looked at the schematic and it could be a couple of things, thee bypass switch, the high cut pot or an opamp (U8)

[K_G_1]

Thanks for all the replies so far and sorry I disappeared for awhile. I've played around with it some more and discovered that I was lying about there only be a hum. If I crank the amp with the gain and volume to 10 there is sound with the varicab turned on, it is just very quiet. The signal is the same through both the record out and effects send - weak, but there. Should I just start replacing the parts you mentioned, or does this development help diagnose the problem?  Thanks again!!

[Dante]

Welcome to the Depot K_G_I!!

Have no fear, you have stumbled across the best place on the web to get your ol' amp back to new (well, old new).

Dante

[MarshallJMP]

Well it should be one of those 3 things I mentioned, maybe start with the opamp.

[K_G_1]

I found the schematics posted elsewhere on the site, and see two op amps labeled U8.  Are you suggesting the replacement of both, or is there one that is more likely the problem than the other? (I've attached a screen shot of the two U8 op amps in the schematics).  Also, there seems to be a huge variety of NE5532 op amps available.  Is there a specific one that would be best for this application?  Are they standardized in terms of pin positioning, size, ect?  Are the op amps available from mouser (http://www.mouser.com/Search/Refine.aspx?Keyword=ne5532) what I want?

Sorry if these are silly questions, but while I have done some circuit board soldering and repair, I am totally inexperienced in terms of amp repair.  Finally, given my inexperience in this area, am I risking the correct operation of the rest of the amp if I screw something up, or is the varicab circuitry totally separate/bypassed until the switch is engaged?  Looking at the schematics, I think its the latter, but I'd like to confirm before I start this project just so I know the stakes involved  :-\.

[MarshallJMP]

Well the NE5532 is a dual opamp, which means there are 2 opamps in one pdip-8 housing. So you actually only need one.
This one will from mouser will be fine 595-NE5532P, I also recommend using a ic socket 575-11043308

[K_G_1]

Well, I opened it up, and I found that the high cut pot (good call on that being a likely culprit) is snapped in half, so I'm​ guessing I don't need to worry about the op amp. I'm going to check at a few shops locally tomorrow to see if I can find a replacement, as the few I found online that match it have a long wait for delivery.

[K_G_1]

Also, I am planning on changing the tubes while I have it torn apart, as they've never been changed to my knowledge.  Any particular 12ax7's that anyone would recommend, or is one as good as the next in a preamp?

[MarshallJMP]

Well, I opened it up, and I found that the high cut pot (good call on that being a likely culprit) is snapped in half, so I'm​ guessing I don't need to worry about the op amp. I'm going to check at a few shops locally tomorrow to see if I can find a replacement, as the few I found online that match it have a long wait for delivery.

Ok look no further, that is the problem. Also make sure you get the "C" 50k !!!

[rnolan]

Wow, wonder how the pot snapped  .  Tubes are very subjective and they all sound different, some not much, some quite allot. Also it's very dependent on the circuit.  I suspect it will be similar to the MP1 so check out the tube threads on here for some ideas.  Tube choice is a hot topic around here LoL