SOLVED = sort of

[mildmanofrock]

I've got a gig tonight and thought it would be a good idea to buy some nice new tubes from the lovely people at Watford Valves. I whipped out the old valves from my Ampeg SVT-6 Pro and didn't note which valves went where. Yes, I'm an idiot, I know.

To cut a long story short, I need to put the original valves back in.

There are four 12AX7 valves and two 12AU7 valves.

I've hunted high and low for a schematic - called Panic Music, spoken to Watford Valves, and left a message with Loud Technologies and no ones entirely sure what goes where.

Can anyone help??? I've attached a picture of the empty valve slots!

Thank you folks!!

Steve

Edited June 12, 2010 by mildmanofrock

[Ou7shined]

A quick search turned up some guys that have the same amp.

Here's 2 of them, perhaps shoot 'em a friendly PM to see if they could have a squint in the backs of theirs.

[url="http://basschat.co.uk/index.php?showtopic=90983&hl=Ampeg+SVT-6+Pro"]1[/url]
[url="http://basschat.co.uk/index.php?showtopic=89989&hl=Ampeg+SVT-6+Pro"]2[/url]

These were just the first 2 there are plenty more.

Edited June 11, 2010 by Ou7shined

[chris_b]

Try John Chambers at Champ Electrics www.chambonino.com

Good luck

[mildmanofrock]

Ou7shined and Chris - thanks so much for taking the time to reply - I really appreciate it.

Problem is solved now - its four 12AX7s in J11, J14 and the front two slots... and two 12AU7s in slots J12 and J39.

Thanks again - people like you make this forum a godsend - cheers!

Steve

[mildmanofrock]

Well, I thought all was fine... then played gig and the sound was very crackly. It was actually going crackly when I first put the valves in. I put the old valves back in - same problem. So back in with the new valves, then I screwed the cover on, put it in the rack case, and all seemed fine... but was not to be...

Does anyone know what the problem might be and if/how it can be solved?

Thank you folks!

Edited June 12, 2010 by mildmanofrock

[escholl]

[quote name='mildmanofrock' post='864978' date='Jun 12 2010, 10:34 AM']Well, I thought all was fine... then played gig and the sound was very crackly. It was actually going crackly when I first put the valves in. I put the old valves back in - same problem. So back in with the new valves, then I screwed the cover on, put it in the rack case, and all seemed fine... but was not to be...

Does anyone know what the problem might be and if/how it can be solved?

Thank you folks![/quote]

was it crackling to begin with, and that was why you initially replaced the valves? It may very likely be a dry joint or loose connection within the amplifier. How handy are you with electronics?

[mildmanofrock]

[quote name='escholl' post='865237' date='Jun 12 2010, 02:49 PM']was it crackling to begin with, and that was why you initially replaced the valves? It may very likely be a dry joint or loose connection within the amplifier. How handy are you with electronics?[/quote]

Hi, I just changed the tubes in an outburst of GAS. There wasn't a crackle before I changed them. I'm not that handy with electronics unfortunately so I think I'll seek professional help!

Cheers

[Lfalex v1.1]

Valve Biasing?

[Mr. Foxen]

[quote name='Lfalex v1.1' post='865516' date='Jun 12 2010, 08:50 PM']Valve Biasing?[/quote]

Don't need it with preamp valves.

[escholl]

[quote name='mildmanofrock' post='865339' date='Jun 12 2010, 04:49 PM']Hi, I just changed the tubes in an outburst of GAS. There wasn't a crackle before I changed them. I'm not that handy with electronics unfortunately so I think I'll seek professional help!

Cheers[/quote]

You may have just wiggled one of the valve bases loose when changing the valves, may have had a nearly dry joint already and the added pressure wiggled it free. Don't worry, there was no way you could have known it would happen. Should be a quick, easy fix for any professional tech.

If you happen to have any contact cleaner, have you tried using it to clean the valve sockets? It is also possible they are just a little oxidised, and just need a bit of a clean.

[Lfalex v1.1]

[quote name='Mr. Foxen' post='865523' date='Jun 12 2010, 09:12 PM']Don't need it with preamp valves.[/quote]
Which will teach me to skim-read posts!
I just read "Ampeg" and "pulled all the valves out"!

[mildmanofrock]

[quote name='escholl' post='865659' date='Jun 13 2010, 12:51 AM']You may have just wiggled one of the valve bases loose when changing the valves, may have had a nearly dry joint already and the added pressure wiggled it free. Don't worry, there was no way you could have known it would happen. Should be a quick, easy fix for any professional tech.

If you happen to have any contact cleaner, have you tried using it to clean the valve sockets? It is also possible they are just a little oxidised, and just need a bit of a clean.[/quote]

Thanks escholl, Ifalex, Mr Foxen...

Escholl... I think you're right - I'm taking it to an amp repairman this afternoon - I don't trust my fat fingers any more!

Cheers,

Steve