Trace Elliot VA400 Help

[ValleyArts]

Hi everyone I have a VA400, when I engage the pre shape or graphic button it makes a weird short hum, it's hard to explain, and the hum also kicks in when you slap. I've attached 2 videos to show what I mean.

 

Hopefully someone knows what the problem is I would like to use the amp as it sounds great but those noises and the hum coming from the amp makes it almost unusable.

[DGBass]

Is the short hum present when using both the valve pre-amp input ( RED ) and the standard pre-amp input ( GREEN ) or does the symptom change when using either input with the shape/graphic buttons? Also are you using the front buttons or a footswitch to activate the shape/graphic?

[ValleyArts]

8 hours ago, DGBass said:

Is the short hum present when using both the valve pre-amp input ( RED ) and the standard pre-amp input ( GREEN ) or does the symptom change when using either input with the shape/graphic buttons? Also are you using the front buttons or a footswitch to activate the shape/graphic?

Hi, the short hum from activating the buttons is coming from the green channel, but if I use both channels together it happens. Also I'm using the buttons to activate them not a footswitch :) 

[DGBass]

That sort of rules out the tube input and a potentially worn tube as that part sits in front of the green channel. Series 6 GP12 pre-amps are pretty solid and most things i've come across with them are usually age/wear issues with stuff like input jack contacts/ dry solder joints on the front board or occasionally some components failures after a long time. These amps are getting on for thirty years old so a few issues are to be expected. The graphic/pre-shape circuit is solid state switching, a couple of transistors and IC chips. Later SMX heads went back to physical relays instead of ICs. Each have good points and bad points for reliability. It could be just worn buttons or a dodgy transistor in the switching circuit but to be honest without getting the amp up on a bench to test, its just guess work. A VA400 is definitely an amp worth repairing so unless its been in and out of a tech shop costing you tons of money to keep it going, I'd keep it and see if you can find a local tech to check it over for you. Some folks on this forum have mentioned Ashdown might look at a Trace Elliot repair and if your in Essex, Heybridge might not be too far to travel and get your VA400 checked out by them. Worth a phone call I would say. 🙂

For the record, I haven't come across buzzing from the pre-shape/graphic on a Series 6 GP12 other than the actual press in switches being worn out. That usually just causes issues actually switching on/off not random hum noises. 

 

[Chienmortbb]

In general electromechanical components, switches, relays and even Jack sockets are less reliable than pure electronic devices like transistors an electronic switches. thirty year old relays, switches and jacks may well have reached the end of their lives, but are replaceable. 
 

[ValleyArts]

On 07/05/2023 at 13:20, DGBass said:

That sort of rules out the tube input and a potentially worn tube as that part sits in front of the green channel. Series 6 GP12 pre-amps are pretty solid and most things i've come across with them are usually age/wear issues with stuff like input jack contacts/ dry solder joints on the front board or occasionally some components failures after a long time. These amps are getting on for thirty years old so a few issues are to be expected. The graphic/pre-shape circuit is solid state switching, a couple of transistors and IC chips. Later SMX heads went back to physical relays instead of ICs. Each have good points and bad points for reliability. It could be just worn buttons or a dodgy transistor in the switching circuit but to be honest without getting the amp up on a bench to test, its just guess work. A VA400 is definitely an amp worth repairing so unless its been in and out of a tech shop costing you tons of money to keep it going, I'd keep it and see if you can find a local tech to check it over for you. Some folks on this forum have mentioned Ashdown might look at a Trace Elliot repair and if your in Essex, Heybridge might not be too far to travel and get your VA400 checked out by them. Worth a phone call I would say. 🙂

For the record, I haven't come across buzzing from the pre-shape/graphic on a Series 6 GP12 other than the actual press in switches being worn out. That usually just causes issues actually switching on/off not random hum noises. 

 

Going to run it down to Ashdown today 😁

Edited May 9, 2023 by ValleyArts