2. amps-preamps
  3. 1171208842

VTL 450 mystery - please help


Hello Folks:

I am now the very proud owner of the VTL MB-450 monoblock. They were built in 1998 and upgraded with every available option in 2003. The seller has an impeccable reputation and I trust him. With that said, something very very upsetting is happening that I could use some advice on.

The first night that I used them, I brought them over to a friends home who has a new PS Audio Premier power conditioner and we plugged both of the amps in and listed for a few hours with no problems. Late that night, after I left, one of the amps B+ fuses blew out.

When I went over to run some tests, we found that both amps tube bias readings are about dead-on and while we were working on one of them with no signal, the other fuse in the other monoblock also blew and I thought I observed one of the tubes near the front of the unit glow unusually bright just before that happened.

The preamp that my friend has is passive, built by Creek and was not muted. The home also has one dedicated power line and one older power line that the other unit was running through.

Bea at VTL told me that sometimes power conditioners inhibit the amount of current that these amp's need to function. She also recommended that I buy a new set of tubes.

Can anyone help?!!

Thanks.

D.H.
danhirsh
jc51373
548 posts
 
Do you have a line dedicted to your system?

If it works for you by all means go for it, I just wouldn't try it. Maybe Shunyata is the exception...I still would not do it.
nrostov's avatar
nrostov
199 posts
 
No I don't. When I got my Shunyata I a/b'ed with the wall outlet. There was a dramatic(and I am talking night and day difference here) increase in dynamics when I plugged my amps into the Shunyata Hydra 8.
dennis_the_menace's avatar
dennis_the_menace
467 posts
 
agree w/ everyone else. just bad tubes, definitely happens, and actually happened to me just this wkend. replace the tubes that blew (in matched pair) and keep the left over for spare, and you should be good to go.
cytocycle
1,043 posts
 
Also your friend might have his PS Audio Premier set for Multiwave and this is not good for you tube amp... check that..

I have experienced that after shipping (moving), I've had problems with tubes that worked perfectly before hand.. the flaring up is a sure sign of a tube problem.

The Shunyata is passive versus these regenerators and balanced conditioners.. so it won't limit current typically.
theduker's avatar
theduker
53 posts
 
Just so people know, there is a rolling update on these amplifiers that lowers the voltages and makes them more "friendly" to modern production tubes. Local dealers can do this, Mine in Minneapolis did... I have lots of VTLs and have had occasional problems with tubes failing, but only when they were old and weak,
More to discover