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
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.
hope this link for ST-85 diagram works https://www.dropbox.com/sh/dwx3uhbl...eX_qs5aZt9Ra/20 Schaltplan VTL St-85.jpg?dl=0
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
- Home
- Amplifiers
- Tubes / Valves
- EL34, KT88, High Voltage?, VTL..