Presence not working. Please Help!

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psychepool
Posts: 260
Joined: Fri Apr 18, 2014 8:29 am

Presence not working. Please Help!

Post by psychepool »

I made a amp that based on Blackface.
To be accurate, It is Mesa Rectoverb clean channel.
http://www.pedalparts.co.kr/shop/board/ ... %26div%3D0

It has very Fenderish sound. I'm very satisfied with it.
Now I remove the capacitors at the gain pot and add a bright switch.
And I can use it as Deluxe Reverb by install the cathode bypass capacitor switch.
And Add a PPIMV. Now I can get hotter sound in bedroom level.

But there is just one trouble.
Presence pot dosen't works at all.

I checked the layout and wiring status several times, but I can't find the different from the circuit diagram.
So I want to ask if there is a problem with the schematic.


And I would like to ask if there is a problem in other areas besides the schematic.
I used Hammond Deluxe Reverb OT.
http://www.hammondmfg.com/pdf/EDB1750H.pdf
frankdrebin
Posts: 131
Joined: Wed May 14, 2014 11:40 am

Re: Presence not working. Please Help!

Post by frankdrebin »

Nfb must be connected, try jumper the 2.7k resistance.
When ppimv is low you have less presence effect.
psychepool
Posts: 260
Joined: Fri Apr 18, 2014 8:29 am

Re: Presence not working. Please Help!

Post by psychepool »

Thanks for advise! I don't install NFB switch.(always connect)

It did not seem to change anything even if set the PPIMV full.
(I certainly do not remember. When I go home I will check again)

I'll try to jump 2.7K. Thanks!
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