SVT - changes after updates

[pbman1953]

More than a year ago I bought a 70's SVT from a friend. I went through and updated the caps. I remember both channels being very strong and quick to reproduce.


I haven't used the amp that much since its more of an investment/studio amp. Turning it on last night I noticed the second channel was slightly overpowering the first channel at the same tone settings. For the selectable midrange , the only frequency that made a difference  , based on a full pot swing back and forth, was the 200 hz. With the 800 and the 3k I hardly noticed a difference.


Does anything come to mind of what I should check?


The amp is still quiet and sounds fine , but the first channel seems to have lost its gut compared o what I remember.


Thanks for any thoughts

[Willabe]

Got a schematic you can post?

[pbman1953]

Got a schematic you can post?

Yes, from the Ampeg site labeled SVT 1972 w/ 6550 tubes

[pbman1953]

This one may be clearer

[tubeswell]

second channel … slightly overpowering the first channel at the same tone settings. For the selectable midrange , the only frequency that made a difference, based on a full pot swing back and forth, was the 200 hz. The 800 and the 3k hardly were noticeable.

So are you saying ‘the channel is okay but the 200Hz selector is quieter’?

[pbman1953]

second channel … slightly overpowering the first channel at the same tone settings. For the selectable midrange , the only frequency that made a difference, based on a full pot swing back and forth, was the 200 hz. The 800 and the 3k hardly were noticeable.

So are you saying ‘the channel is okay but the 200Hz selector is quieter’?

For any SVT owners out there you know that the amp is strong and reactive to string touch. Channel 2 has that effect where 1 is still good but doesn't have the attack of 2.

For the mid eq statement , I had to go back and modify that line, above. With the 200, sweeping the pot back and forth you hear the increase and decrease of the frequency. With the 800 and 3k , even with playing on higher strings (D & G) there wasn't much a difference at all.