Mesa 50/50 deep mod
- Thread starter Warheart
- Start date
glassman
Electron Herder
Re: Mesa 50/50 deep mod
There are two different ways of doing it. All it does is flattens out the frequency response of the amp; the amp is set up originally to accentuate the mids and highs. The 50/50 mod would be the same as the 20/20.
(1) remove the cathode bypass caps on the first stage of each channel. This effectively lowers the gain of the mids and highs to the level that the bass is already at.
(2) replace the cathode bypass caps with a larger value (10uF - 250uF). This will bring the bass gain up to the level of the mids and highs and allow you to select the bass roll off point with capacitor selection (10uF will be significantly fatter than the 1uF that is in there and a 250uF may be too much).
Personally, I would go with #1.
If you're not used to working with high voltage, leave this to a professional!
There are two different ways of doing it. All it does is flattens out the frequency response of the amp; the amp is set up originally to accentuate the mids and highs. The 50/50 mod would be the same as the 20/20.
(1) remove the cathode bypass caps on the first stage of each channel. This effectively lowers the gain of the mids and highs to the level that the bass is already at.
(2) replace the cathode bypass caps with a larger value (10uF - 250uF). This will bring the bass gain up to the level of the mids and highs and allow you to select the bass roll off point with capacitor selection (10uF will be significantly fatter than the 1uF that is in there and a 250uF may be too much).
Personally, I would go with #1.
If you're not used to working with high voltage, leave this to a professional!
glassman
Electron Herder
Re: Mesa 50/50 deep mod
It sounds like you made it how it should have been all along! Enjoy!
It sounds like you made it how it should have been all along! Enjoy!
glassman
Electron Herder
Re: Mesa 50/50 deep mod
There are two 15uF @ 35 volt electrolytic caps on the board; they are the only two capacitors of this value in the amp. They both bypass 2.7k ohm resistors. simply cut the caps out, leaving the resistors in place.
As always, if you are not accustomed to working with high voltages, leave this to a pro.
Oh...and welcome to the forum.
Please someone. Where do i do the deep mod on my old Fifty/Fifty ???
Cant seem to find any likeness with the 20/20 mod
There are two 15uF @ 35 volt electrolytic caps on the board; they are the only two capacitors of this value in the amp. They both bypass 2.7k ohm resistors. simply cut the caps out, leaving the resistors in place.
As always, if you are not accustomed to working with high voltages, leave this to a pro.
Oh...and welcome to the forum.
Re: Mesa 50/50 deep mod
Hi!
Old thread I know but would love to know if it is ok to make this option switchable?
If I install a true bypass switch on those capacitors will it cause damage to switch it on and off of the circuit? Or I need to provide a path to ground when the capacitor is out to allow it to discharge? Or I don't know what I'm talking about and just asking for trouble?
The later sounds likely... but if it can be done I'd love someone to show me how! I have quite a lot of experience with a soldering iron so executing the mod won't be a problem, I'm just no electronic expert....
Thanks!
Hi!
Old thread I know but would love to know if it is ok to make this option switchable?
If I install a true bypass switch on those capacitors will it cause damage to switch it on and off of the circuit? Or I need to provide a path to ground when the capacitor is out to allow it to discharge? Or I don't know what I'm talking about and just asking for trouble?
The later sounds likely... but if it can be done I'd love someone to show me how! I have quite a lot of experience with a soldering iron so executing the mod won't be a problem, I'm just no electronic expert....
Thanks!
