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VTL ST-85 Repair

I have a 2002 VTL ST-85, which has of late been blowing the main fuse (6A, slow-blo). Rather than bring the amp to my local dealer (who would be happy to look at for at least $150), I'd like to have a go at repairing it myself. (As background, I'm an EE with some analog circuit experience.)

Most books I've found covering tube amp repair are written for guitar amps, not stereo amps, though I'm sure the principles are basically the same. As some may have already discovered, VTL is extremely restrictive about who they'll send documentation to - end users of their equipment don't qualify.

So, I'm looking for suggestions of good titles covering stereo tube amps, or perhaps specific suggestions regarding my particular problem.
melodious_vibrationz
oddiofyl's avatar
oddiofyl
3,887 posts
 
First check the cathode resitor between the tube socket and the test point. I have had these go out of spec and cause the tubes to draw excessive current, blowing the main fuse. I had a few tubes get red hot and the bias seemed OK at the test point, the resistor was out of spec and was something like 18 Ohms instead of 10 Ohms.

I would never buy another VTL again, it sounded great when it worked but they don't even want to service older products.
samujohn's avatar
samujohn
291 posts
 
The VTL book (the original one if possible), and Valve Amplifiers by Morgan Jones ISBN 0-7506-4425-7.

Luke Manley is a nasty piece of work. I had VTL's but no more.Too bad cause David was an excellent designer.
melodious_vibrationz OP
4 posts
 
Thanks Oddiofyl & Samujohn for these tips.

Regarding Mr. Manley, its not hard to find some fairly venomous opinions of him at various audio sites. VTL definitely builds some sweet-sounding equipment, but seems fairly disdainful when it comes to customer service. My local dealer has even quit carrying their stuff because of the hassle. C'est la vie.

I'll definitely consider other tube manufacturers next time around.
oddiofyl's avatar
oddiofyl
3,887 posts
 
I agree Luke Manley is the rudest, most arrogant person I have ever had the displeasure of speaking to in my life. An absolutely horrible experience dealing with him after he renegged on his "lifetime warranty", what a scumbag.
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