Official M2 schematic

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#962
The 9 pin all in one is an easy build, and not too expensive to build. I built the 9 pin and after that a no holds barred dual mono because I was so impressed with the sound. The dual mono sounds like the all in one, just a lot more expensive, go with the all in one.
 
#963
PJN said:
The 9 pin all in one is an easy build, and not too expensive to build. I built the 9 pin and after that a no holds barred dual mono because I was so impressed with the sound. The dual mono sounds like the all in one, just a lot more expensive, go with the all in one.
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Do you have a link to the schematic you used? I built and am using this very simple tube pre build and I enjoy it very much but then I like a healthy dose of 2nd harmonic. I did change the design a little for just the 12AU7 tube.

4S Universal Preamplifier for 12A*7 Tubes

It does not get much simpler than this circuit.
 
#965
PJN said:
The 9 pin all in one is an easy build, and not too expensive to build. I built the 9 pin and after that a no holds barred dual mono because I was so impressed with the sound. The dual mono sounds like the all in one, just a lot more expensive, go with the all in one.
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Although I have two 9 pin mini twin triode tube preamps on hand, (with phono stages) I not a big fan of them any longer, future builds will be with 8 pin octals. If one is a fan of 12au7, try 6ns7 types

Russellc
 
#970
Nelson Pass said:
It would allow you to play with it. That's a real advantage.

😎
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Nicoch,

in response to your PM: The arrangement to add a trimpot to the input stage of the M2 looks like the attached.
The snippet is taken from p.2 of the F5Turbo article by Nelson.
 

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#973
generg said:
İ put a piece of Mu metal over the small transformer only, first.
I had still some hum.

It was gone completely, when I shielded the transformer also, this contributed more to silence than the small shielding.
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Hi Generg,
Can you show a picture on how you shield the transformer? My friend is experiencing hum when the PS board or the rectifiers are close to the amp module/Input transformer. Even if just the rectifiers close to the input transformer will cause hum. No hum if we put all the power supply cap bank, rectifiers and power transformer in another case or away from the amp module. We have also noticed that the rectifiers gets quite hot and vibrates, is that normal ?


Thanks
 
#975
I noticed a 3db increase on my left channel without the star ground. Im going to try running a separate ground from: supply-board-thermistor-ground and see if that lowers it, I also read that shielding the power transformer is better than shielding the input transformer. Overall my un-shielded M2 is buzzing about 6db louder than the F6 on 115db/w drivers.

On Antek transformers their is a shield wire, where is the best place to connect it?
 
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#979
To make it clear:

You want the shield to be connected to a point which has the biggest distance to your audio signal, and also from the audio ground. And this is the ground/earth from the AC mains, where it gets into your amplifier's case. You can put it to the connection, where you grounded your case (so where the ground/mains connects to your case).
A picture does say more like 1000 words (especially if it's not your mother tongue 😉 )
 

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#980
Member - @ wdecho has twisted my arm as we have similar speakers and he loves the M2
Have joined & ordered the M2 in group buy scheme from @ teabag

So hopefully in a couple of months I will have the parts delivered and have the M2 amp built
I'm just looking at a self assembly chassis using Conrad heatsinks - Conrad Heatsinks - Products

I could do some nice work with the MF20 double flange heatsinks
You have to start planing early ( so they say )

FR
 
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