I have a sin to admit to. I strayed away from the flock for a period of time and built 3 SET amplifiers and I have to admit I preferred one of them over the 3 previous Firstwatt clones I had previously built with my very efficient horns. Now my go to amp is this M2. I did a short A/B last night with some Joe Bonamassa music between my best SET and the M2 and the SET was slow and dull compared to listening with the M2. With acoustic music the preference may change. Too early and not enough A/B ing to form an opinion. I honestly think it is going to take a SIT Vfet build to top this M2 with my horns but then I have never heard the F3 or the J2 or the F7.
Well I took a look at swapping out my aleph boards for the M2 boards in my existing aleph J amp, no go, the case was a DIY custom build and the heat sinks are too short to mount the boards, need longer sinks like I used in my previous F6 build. There is no way I want to dismantle my F6 which leave me with the realization that I need to build another amp. I priced things out and the 400 MM 2U in the DIY audio store is the clear choice. It would cost almost as much to DIY a case with all of the hassle that goes with it. I'll steal a PSU out of a dual mono Honeybadger that I have, that has 40,000 uF per rail to help defer costs.
Dont know how the case was assembled, but I extended one of mine by using angle aluminum on each side of the heat sink. The angle material was 1" on one side and 2" on the other, giving up to 4" longer chassis. You would need a new longer top, bottom may be able to be left as is, just giving a little more ventilation...
Russellc
Hello Wdecho, you are the one that is going to force me to build the M2. I have been a long time lurker in these threads and now I am going to take the plunge and build a Pass designed amplifier. I will be starting to source my parts here in the next month or so and plan to have it done by June. TBH I only have one SS amp.
On another note, without a question the largest contributer to sonics (besides the speakers used) is the audio transformers. I believe the 6CB5A amp you used has Edcor iron. If you really like that amp I would probably splurge for something better. Also I would recommend you try a couple tweaks like adding some large oil/film caps in parallel with the electrolytic in your power supply. On top of that I would add as large a grid stop resistor on the 6CB5A (as big as you can go without rolling off the highs) and also lower the g1's circuit resistance, lower the 500k to around 220k, it shouldn't load the 6N7 down. Adding the grid stop resistor will limit any grid current drawn during transients and lowering the grid leak value will help with any bias excursion response time (in conjunction with the coupling cap). I do really like Edcor transformers and I use them all the time for budget stuff but tubes really start to sing with better iron.
Back to the M2. I have not read through all the posts so excuse my ignorance but I would like to propose that when I do build the M2 I will start with the interstage transformer and then experiment. How about a very linear triode stage for voltage gain for a sort of "hybrid" amp instead of the step up transformer? I noticed that with the 1:5 transformer the amp requires some serious sources to get it to full power anyway, maybe a power triode with really low plate resistance could do the trick?
End rant.
Unfortunately it is not a build that is easily modified, I'll just save my pennies for a 2U 400 mm.
Paul
it's better as autoformer , on all accounts
in "normal" way , you'll need completely different beast , which would be benefitiary only if you can exploit galvanic isolation to avoid cap coupling
as always , amplifier is full sack of compromises
in any case - take M2 as ideally cut diamond , which it really is
no bloody part redundant
in "normal" way , you'll need completely different beast , which would be benefitiary only if you can exploit galvanic isolation to avoid cap coupling
as always , amplifier is full sack of compromises
in any case - take M2 as ideally cut diamond , which it really is
no bloody part redundant
I have a stupid question....
For my M2 HPA build I bought this Cherry Rocker switch RR series.
It has a little light bulb inside with a resistor. It measures about 37 Ohm between 1 and 3.
To get it lit, I have to put 12V DC on it ???? How do I connect this?
I can get 12V DC from somewhere after the superregulators, but I don't think it is wise to connect it that way
Because when switched to 'on' there is 230V on one side of the bulb....
I think it must be something simple, but can't find the solution
Hope somebody can help me out.
For my M2 HPA build I bought this Cherry Rocker switch RR series.
It has a little light bulb inside with a resistor. It measures about 37 Ohm between 1 and 3.
To get it lit, I have to put 12V DC on it ???? How do I connect this?
I can get 12V DC from somewhere after the superregulators, but I don't think it is wise to connect it that way
Because when switched to 'on' there is 230V on one side of the bulb....
I think it must be something simple, but can't find the solution
Hope somebody can help me out.
Attachments
Interesting circuit. Actually it must be possible to convert this circuit in two circlotron stages, so it is possible to operate with only n-channel jFET and MOS-FET.For all the Greedy Boyz,
The M2 officially discontinued, here is the official schematic, assuming that
it has not otherwise been posted.
In particular note the interesting bias circuit that you can use elsewhere.
The disadvantage of using four power supplies for one channel is offset by the advantage of being able to select good available semiconductors and get even better sound quality - so I think.
To find the right and at the same time good available FETs, check out this threads:
http://www.diyaudio.com/forums/solid-state/165116-best-audio-power-mosfet.html
http://www.diyaudio.com/forums/pass-labs/146310-bf862-preamp.html
I have a stupid question....
For my M2 HPA build I bought this Cherry Rocker switch RR series.
It has a little light bulb inside with a resistor. It measures about 37 Ohm between 1 and 3.
To get it lit, I have to put 12V DC on it ???? How do I connect this?
I can get 12V DC from somewhere after the superregulators, but I don't think it is wise to connect it that way
Because when switched to 'on' there is 230V on one side of the bulb....
I think it must be something simple, but can't find the solution
Hope somebody can help me out.
I use those types very often, you should buy one which marked 120/230V that has the proper resistor for the bulb to. I think that is the least problem if you use that. That made for car use and I'm not sure will handle the 230V for long term. I would not use that in my amplifier.
Greetings
So heres a fun fact, the secondary output on the Altek (Antek for clowns) transformer should be positioned as far away as possible from the Edcor's, the wire itself doesn't add any noise. It was causing all the extra hum on the right channel.
Iv'e also noticed that Papa does this. Smart guy!
Iv'e also noticed that Papa does this. Smart guy!
Attachments
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bloody linear change
(I believe something will be soon scorched with 30V rails )
Ok then I will try to use the standard 0R47 on 30V rails...Current draw is aprox. 1.3A I read here...39W dissipation is ok!
No schorching will occur!
What about the 221R resistor should I change it to ZERO whit 0R47R or not???