The main issue I personally would have with your suggestion an giving the amp back to
the customer is the removing of the 10ohm cathode resistor and biasing the amp with a
scope, at that point the customer has no clue how to check his amp, replace tubes, ect.
Cathode bias and triode are things known and understood, even for the guy just listening.
(I do appreciate the suggestions though, thanks)
Cheers,
Keg
the customer is the removing of the 10ohm cathode resistor and biasing the amp with a
scope, at that point the customer has no clue how to check his amp, replace tubes, ect.
Cathode bias and triode are things known and understood, even for the guy just listening.
(I do appreciate the suggestions though, thanks)
Cheers,
Keg
This link isn't of the st-85 but the st-75 would be very similar, but it uses kt90s instead of el34s.
http://w3.uniroma1.it/chemo/image/hifi/VTL-stereo75-schematics-mod.png
http://w3.uniroma1.it/chemo/image/hifi/VTL-stereo75-schematics-mod.png
That is lunacy; 550V on U-L rigged audio tubes? I have no issue doing this( actually 600V ) to 813 and 4E27, but they are not in the same class as these KT90...LOL
cheers,
Douglas
cheers,
Douglas
I had my 1998 st-85 rebuilt new caps the board and beefed up bias circuts and ceramic
tube sockets cardas binding posts and rca jacks with Mullard reissue kt88's
worth every damn cent. Don't tall Bea at VTL thay will say i'm wrong.
tube sockets cardas binding posts and rca jacks with Mullard reissue kt88's
worth every damn cent. Don't tall Bea at VTL thay will say i'm wrong.
I repaired a VTL amp using Triode connected 807's running at 600 volts. When I received the amp some one had set the Bias to 70Ma and the 807"s where bright red. Found out from VTL that it should be set to 26Ma. Later I built a Triode 807 amp Fixed bias and ran it at 560 volts for many years. No problems. The data recommends no more than 400 volts, cathode bias.
Phil.
Phil.
That was the reason for the tube switch from el34's to kt88's, the amp was eating tubes every 300 hours or so.
circuit diagram vtl st-85
Hello,
because I did not find a diagram, I have drawn one. Sorry I am not an artist. Power supply was left out. Please send me PM for request. Don´t know how to insert a .jpg file here.
best regards, frank🙂
Hello,
because I did not find a diagram, I have drawn one. Sorry I am not an artist. Power supply was left out. Please send me PM for request. Don´t know how to insert a .jpg file here.
best regards, frank🙂
hope this link for ST-85 diagram works https://www.dropbox.com/sh/dwx3uhbl...eX_qs5aZt9Ra/20 Schaltplan VTL St-85.jpg?dl=0
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