friedman post phase master design

[Suckseeder]

I have a Friedmann Plexi on the bench. Close to this schematic, but single 250k pot cross line MV!
Coupling Caps .1 , 100pf snubber , 2M2 bias resistors

 

[RealAmpsAreDead]

I have a Friedmann Plexi on the bench. Close to this schematic, but single 250k pot cross line MV!
Coupling Caps .1 , 100pf snubber , 2M2 bias resistors



View attachment 457270

Are you sure it‘s not a dual gang pot?

 

[Suckseeder]

Are you sure it‘s not a dual gang pot?

Absolutely, I was surprised too

 

[RealAmpsAreDead]

Absolutely, I was surprised too

Weird…How exactly is it wired then?

 

[Suckseeder]

Look at the MVC pot, same size like the others. 2 core with shielding

 

[Suckseeder]

Weird…How exactly is it wired then?

 

[Suckseeder]

The pot reduces resistance between the lines. Because the two audio signals are perfectly mirrored (180 degrees out of phase), they cancel each other out. This cleanly starves the power tubes of the signal, dropping the volume.

 

[MacMeda]

Can this be installed in a 1987X

 

[Suckseeder]

Can this be installed in a 1987X

Yes

 

[MacMeda]

Yes

I am not a tech but really could use an mv in my 1987.
Is this all I would need to show a competent tech ?
Do you feel this is a better option to the Rich or Lamar ( or anything else)
Thanks
In San Diego

 

[FourT6and2]

I am not a tech but really could use an mv in my 1987.
Is this all I would need to show a competent tech ?
Do you feel this is a better option to the Rich or Lamar ( or anything else)
Thanks
In San Diego

If a competent tech doesn't already know what Lar/Mar PPIMVs or this version are... they are not a competent tech and I would find someone else. This stuff has been around for 40-50 years. If they need a customer to tell them what it is, run.

 

[MacMeda]

If a competent tech doesn't already know what Lar/Mar PPIMVs or this version are... they are not a competent tech and I would find someone else. This stuff has been around for 40-50 years. If they need a customer to tell them what it is, run.

The guy I just spoke to asked if 1987X was a car.
Then I asked what type of MV he liked to use and he said “ The best” , I ran

 

[RealAmpsAreDead]

If a competent tech doesn't already know what Lar/Mar PPIMVs or this version are... they are not a competent tech and I would find someone else. This stuff has been around for 40-50 years. If they need a customer to tell them what it is, run.

I think his question was just what PPIMV is the best option in the end. Interesting question. Did someone compare the Friedman Plex one to the others?