VTL tiny triode 25 limited edition

[mcgjohn]

Tried recapping the unit and reassembling it. Ran into an issue. When I first powered it on I used a dim bulb and there were no issues. Unfortunately I'm getting about -600v on all of the bias points. No smoke and nothing obviously fried.

I tried using 0.1uf film bypass caps on two of the large capacitors and ended up clipping them out to see if that was the issue but it wasn't.

All of the caps seem to be the right value and in the right orientation. Must be something wrong with the way I wired it.

I think maybe something is touching something it's not supposed to. I'm not a hundred percent sure I reinstalled the RCA jack correctly but I don't think this would cause the issue.

If you did only one amp, you can use the other amp to double check all your connections.
Sounds like a connection may have ended up at the wrong wiring contact.

 

[Will2225]

I found a local shop near me and paid them to check it out. It's a bit too nice of an amp for me to afford to make any mistakes on it. I'll find out in around ten days or so. They thought it was either a resistor or maybe I had lost ground connection.

 

[mcgjohn]

OK good. post what you find out. they are nice amps.

 

[Will2225]

So it turned out on the faulty amp it had lost the ground connection to the board due to a fault in the circuit board. I paid them to add a jumper to restore ground and it works great now.

Ive been listening to one pair of them for awhile and they sound great. The tech checked both of them and said there really wasn't much hum but for some reason I'm getting a small amount of hum in my system. Not enough to really bother me though. I think it's most likely my tube pre amp.

I should probably try to recap the second amp in this pair but right now I'm just enjoying listening to them.

 

[mcgjohn]

they are nice amps with more eff. speakers.

 

[Will2225]

Yeah I like them a lot. I'm using Tannoy Mallorcans, so pretty efficient speakers.

The tech I ended bringing them to was great, only took about 9 or 10 days to fix them and wasn't that expensive.

 

[styua]

@mcgjohn do you what the fifth bias point is for? The one that's separate from the rest. There's also one trim pot on the underside of the board that I'm not sure what it's for.

Regarding bias, from web pic I collected, it indicated 200mV but pic named 185mV suggested. Again this is TT25 old version for your reference only. Pic labeled 5th pot as "ne pas toucher" (do not touch, LoL). Hope VTL get back to you.

 

[Will2225]

Thanks for the info. I might change the bias to 185mv. They sound really good as is at 200mv and el84 tubes aren't too expensive.

VTL never got back to me but I don't really blame them. The amps are probably over 20 years old at this point.

Quite happy with them though. Have to decide if I want to do the work on the other pair myself or ask this tech if he would be willing to do it.

The hum is a little strange. Its only happened a couple times and hasn't happened at all today. I definitely think it's something in the rest of my set up causing it.

My set up is kind of a rats nest of wires. Rainy day here, might get around to doing some cable management and tidying things up a bit.

 

[Will2225]

Just wanted to follow up on this thread. I have been listening to first pair for the past few months and have really been enjoying them.

I decided to try the other pair again and get back to troubleshooting them. I adjusted the bias on them and no hum at all. The bias on one of the monoblocks seemed to shift a bit. Luckily, I ordered replacement NOS Soviet el84s and replaced all of the power tubes and set the bias. The sound is excellent! With the new tubes this pair of monoblocks sound even better than the pair I've been using for the last few months.

I'm not sure why I was having hum in them originally but now both pairs of monoblocks are up and running well! I definitely need to order another 8 el84s for the other pair as the new tubes made a big improvement.

 

[Will2225]

I gave them a good cleaning. They look much better now.