PG M25 info needed

[Bertje]

I'm modding a Route 66 (M44 + M25) to a full 6 channel amp, with 6 inputs (normally 4). Therefore I need to transform the M25 pcb in the Route 66 into a real M25, with RCA inputs and gainstage etc.
I need a defect M25 (or a very cheap one ), or a sharp photo of the resistor/capacitors....
Thanks a lot!
Rob.

[wooferdog]

Here's a link to the mod if this is what you want to do.

http://download.phoenixphorum.com/Manua ... 66_Sub.pdf

[Bertje]

Thanks, but i knew that one. The purpose of my mods is to make a 6ch fullrange with 6 inputs from the route 66. There are a lot of 6ch DSP's to drive this nice amp.
So I need a M25 and replace this for the M25 in the Route 66...

[LowandLoud]

This is something like i wish to do. If only there was a way to just swap it out, but im sure the inputs and all the pots will not line up without drilling\filling holes. Too bad, i do have another M25 i could use for this.

LL

[Bertje]

The original M25 pcb is exactly the same as the M25 part of the Route 66, but only the gainstage potmeter, RCA sockets and all the caps/resistors/opamps are not mounted on the pcb. So you only heave to drill three holes...
If someone knows a M25 for sale, please PM.

[LowandLoud]

After looking closer, i see what you are saying. Im not sure why but i always assumed the m25 was on the right side. Its not, lol. so ya, 2 holes for pots, 2 more for RCA inputs and its a 6 channel. The only thing missing would be the output RCAs for the m44. No big deal.

My only issue with it is modding a SE amp. I will have to think on it. But thanks for giving me a solution to a problem i have been thinking about for a few weeks.

LL

[Bertje]

Today i did succeed in analyse (and draw) the inputcircuit of the M25, just a single gainstage and bypass the useless bassboost section, tbc...

[trickyricky]

So you are going to add a pair of rca's and a potentiometer for the gain?

[LowandLoud]

Someone sell this man an M25 so he can perform this mod, lol. I guess this stuff is a little harder to find over where you are. I keep an eye on the local buy and sell and seem to find quite a bit of PG stuff. I just bought another M50, not because i need it, but just because he was 3 blocks away and i talked him down to $40.

Good luck, although it sounds like you have it pretty well figured out. Post lots of pics when you get it finished.

LL

[Bertje]

I'm going to replace the gainpot from the M44 sub-part to the M25, and add the components needed for the gain pre-amp (opamp, resistors, caps, rca sockets). Only adding a gainpotmeter and the rca sockets is not enough...
There are some very good M25 for sale overhere, but way too expensive for this purpose ($120,00 i think..)

[trickyricky]

I got a m25, do you need close up pics? I would sell mine but for no less than 80 bucks (got brand spanking new caps, burr brown opamps).

[Bertje]

This afternoon I succeed in putting all the parts on the pcb and it's working! Opamps are the National LME49720, I allways use this one when possible, very low distorsion, nice sound. But Burr Brown OPA2134 or Philips NE5532 are very nice...
Also did a mod on the input sensitivity, 0,2-2V range is a bit low today. I have to tweak it a little more to get 4V.

Some pics:
new caps:

Empty pcb:

PCB with some new parts...