Mayfield
06-14-2009, 10:42 AM
I have a mid 80's JCM 800 Marshall combo amp that has been my go to amp for decades.
About two years ago I took it to a fantastic amp builder to get tuned up and add a couple of mods. She came back a new amp. Absolutely amazing! Now this is a model that has the high and low imputs. When I got her back, the first thing I noticed was when I plug into the low input I had warm crunch OD at low volumes!! It was AMAZING! Now I could use it more for recording and use at home. I was thrilled at this unexpected change!!
Snap to a few years later....about two months ago...I plugged into the low input like I normally do and .,.....nothing. The OD crunchy tones were gone. Insead the warm cleaner sounds were back from the low input So I am back to using the high input for more dirt, which still sounds incredible.
I took it to another well renown tech god and he gave it a clean bill of health (as a side note..when I dropped it off he had 4...count em 4 original Super Bass and JTM 45 heads that a collector just brought to him to restore! He could barely get me out of there!)
Anyway....the amp has checked out clean...mods are great, board and parts are all tip top. I explained the change and we could not find anything that was wrong. We tested a similar head version he had in his shop and it sounded almost identical to mine.....warm and cleaner on the low channel, which makes sense since it does not engage a gain stage.
So I throw this out to the wisdom of the TGPers......what caused this mysterious Santana like gain to pour out of the low input for years only to vanish into the wind?
About two years ago I took it to a fantastic amp builder to get tuned up and add a couple of mods. She came back a new amp. Absolutely amazing! Now this is a model that has the high and low imputs. When I got her back, the first thing I noticed was when I plug into the low input I had warm crunch OD at low volumes!! It was AMAZING! Now I could use it more for recording and use at home. I was thrilled at this unexpected change!!
Snap to a few years later....about two months ago...I plugged into the low input like I normally do and .,.....nothing. The OD crunchy tones were gone. Insead the warm cleaner sounds were back from the low input So I am back to using the high input for more dirt, which still sounds incredible.
I took it to another well renown tech god and he gave it a clean bill of health (as a side note..when I dropped it off he had 4...count em 4 original Super Bass and JTM 45 heads that a collector just brought to him to restore! He could barely get me out of there!)
Anyway....the amp has checked out clean...mods are great, board and parts are all tip top. I explained the change and we could not find anything that was wrong. We tested a similar head version he had in his shop and it sounded almost identical to mine.....warm and cleaner on the low channel, which makes sense since it does not engage a gain stage.
So I throw this out to the wisdom of the TGPers......what caused this mysterious Santana like gain to pour out of the low input for years only to vanish into the wind?