I did reverse them "for the fun of it" to no avail. No difference.
I put it all back as I found it and gave it back to my friend.
I guess the "gimmick" is the answer I will have to go with.
Thanks for y'all's input.
I don't understand what's happening here
Moderators: pompeiisneaks, Colossal
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Re: I don't understand what's happening here
OK, what I want to know is who came up with the idea (and solution) to add the coil of wire? The guy's certainly a genius, we need him to join the forum and start solving some amp problems....
Most people stall out when fixing a mistake that they've made. Why?
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Re: I don't understand what's happening here
I came upon a similar thing in one of my first Mesa amps I was working on and found out why it was there.
This amp ( and all of this model Mesa amps) had a white wire coming off the plate of a preamp tube gain stage, and this wire was then rapped 3 times around the grid wire for that gain.
I said to myself when a saw this that someone must of been playing games at the factory when this amp was made so I removed the wire, finished the repair that I was making and fired up the amp while looking at the output wave form.
In doing that a saw very clearly that the amp was now oscillating when it was not before, and nothing I did repair wise could have caused that other then removing that wire.
When I reinstalled that wire the oscillating problem was gone!
With that wire Mesa was curing a oscillating problem with reverse feedback, and yes this crutch of a fix that they implemented is also why this model Mesa has such a mid heavy honky tone to it, since that reverse feedback fix also acts to cut high end responce.
This amp ( and all of this model Mesa amps) had a white wire coming off the plate of a preamp tube gain stage, and this wire was then rapped 3 times around the grid wire for that gain.
I said to myself when a saw this that someone must of been playing games at the factory when this amp was made so I removed the wire, finished the repair that I was making and fired up the amp while looking at the output wave form.
In doing that a saw very clearly that the amp was now oscillating when it was not before, and nothing I did repair wise could have caused that other then removing that wire.
When I reinstalled that wire the oscillating problem was gone!
With that wire Mesa was curing a oscillating problem with reverse feedback, and yes this crutch of a fix that they implemented is also why this model Mesa has such a mid heavy honky tone to it, since that reverse feedback fix also acts to cut high end responce.
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
- martin manning
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Re: I don't understand what's happening here
Clearly a negative feedback loop, via the capacitive coupling of the wire wraps on the grid lead. That sort of thing is not uncommon in RF circuits, as mentioned above. The remote coil in the amp in this thread is something different.
Re: I don't understand what's happening here
Yep, I've seen this in a Mesa amp, too. But as I recall, the wire went to a different tube? Maybe reverb circuit or maybe your recollection is better than mine. In fact, it might have gone as far as the output section? But it was a long wire in the amp I saw, not something that attached to the first preamp tube.
Most people stall out when fixing a mistake that they've made. Why?
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Re: I don't understand what's happening here
My mind is not 100% sure it, it may have gone to the grid of a different tube like you recall, but I think it stayed in the preamp section and did not go into the output stage.
Once again though I am not 100% certain.
Once again though I am not 100% certain.
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!