see post #2152
your measured values are better than what i had.
later i have changed R3/R4 to 20R pot
got 0V at point C
no audible performance difference.
A.
your measured values are better than what i had.
later i have changed R3/R4 to 20R pot
got 0V at point C
no audible performance difference.
A.
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my M2 is playing really nice for some weeks now buttttt...
i don't get it to work within the proclaimed specs on the attached scheme.
point A is 72mV,
point B is -64mV,
point C is 5mV,
voltage across R13/14 is 600mV,
voltage at optocoupler is 1-2: 1.047V
4-5: 10.4V
offset is fine
same on both channels.
all parts from Teabags BOM except Q1,2 = FQA
and Q3,4 = 8.84mA selected Toshibas from NicMac.
am i splitting hair or is there a real bug?
any input welcome
i was referring to the schematic Atilla I attached to his post #2454
see post #2152
your measured values are better than what i had.
later i have changed R3/R4 to 20R pot
got 0V at point C
no audible performance difference.
A.
thanks. wasn't sure about the -2mV at Pin 1 of the Edcor on one of the channels.The Toshiba 1530/201 sound great.
M2 is for Sissies !
![]()
That’s why you love it so much 😛
A sensitive amp for sensitive speakers
that's trivial , feeding two channels with antiphase (balanced) taking output from two hots
properly bridged M2 demands proper differential autoformer , so you can input either SE or balanced signal , having all virtues of full (differential) signal through one magnetic circuit
that way only output stages are on elevated levels of independency from each other
in layman terms - two separate channels fed with antiphase signal - same as two legs commanded with slightly drunk brain
proper differential input ......... legs are acting together , brain right as after first morning coffee , chill and sound
properly bridged M2 demands proper differential autoformer , so you can input either SE or balanced signal , having all virtues of full (differential) signal through one magnetic circuit
that way only output stages are on elevated levels of independency from each other
in layman terms - two separate channels fed with antiphase signal - same as two legs commanded with slightly drunk brain
proper differential input ......... legs are acting together , brain right as after first morning coffee , chill and sound
After some more effort, my M2 now resides in a more stable and portable chassis. The chassis is almost entirely recycled and left-over parts. The sinks was a flea market find for $6, the top plate is one of my veneer test panels that I made when I built my FHXL speakers, and the front and back panels are scraps from the garage. The only new purchases for the chassis were the aluminum brackets at the rear to provide room to mount the mosfets appropriately on the sink and a handful of screws. The sinks appear to be a good size for this amp, they only see a 20c rise after more than an hour.
The chassis is 12" wide, 12" deep, and 8" tall. The bottom of the sinks are elevated about an inch above the tabletop by the front and rear panels. The bottom is open and the hole in the back panel provides air circulation through the chassis. The input jacks are temporarily on pigtails while I wait for proper ones to arrive - the current ones are too small in diameter (cheap crap from Chinese seller on e-bay). Not even the super-tight Monster cables can hold these jacks tightly. This is my second amp to use my modular power supply. F4 was my first and Aleph-J will be my next.
Now it's time to spend some time listening 😀
Your idea of a modular power supply has interested me for some time. I have thought of stripping a couple of the power supplies out of my amps and building one to power all. My BA3 has a monster and would likely leave it as is. The M2, Aleph J and others could benefit.
My F5 has 2 Antek 300 VA and double Peter Daniels Power supplies. The others have 1 Antek 500 VA and Teabag power supplies.
2 of those 500VA and double Teabag power supply boards would be over kill, but I like over kill.
I have though they would be connected with something like power Conn, and short fat wires.
Problem is, having used power Cons on a build or two, they really don't allow for as fat a wire as I have thought of, and maybe it isn't necessary.
Is there a build thread for yours? It sure may give my M2 some more cajones!
In reference to post 2677.
Your "correct" ps schematic is how i did my build.I have a 500va antek non shielded toroid toward the back of the chassis (close to the edcors which are not shielded).The rectifier bridges (2 cheap square fwb) next and finally the diy ps board (36kkuf/0.1R/36kuf) close to the front of the chassis.Measured ripple is 40mv rms both rails. I have no hum.I've used this ps for an aleph j,F6,F7 ish and all configurations are dead quiet.I don't understand why all the people have hum?
Same here, 500 VA Antek just as you say, no probs here either.
Russellc
I have extra loaded M2 boards and am thinking of building another with the Toshiba outputs.thanks. wasn't sure about the -2mV at Pin 1 of the Edcor on one of the channels.The Toshiba 1530/201 sound great.
Did you do any of the suggested resistor changes or just use Toshibas?
Russellc
that's trivial , feeding two channels with antiphase (balanced) taking output from two hots
properly bridged M2 demands proper differential autoformer , so you can input either SE or balanced signal , having all virtues of full (differential) signal through one magnetic circuit
that way only output stages are on elevated levels of independency from each other
in layman terms - two separate channels fed with antiphase signal - same as two legs commanded with slightly drunk brain
proper differential input ......... legs are acting together , brain right as after first morning coffee , chill and sound
Thanks ZM - great analogy !!! 😀
I have extra loaded M2 boards and am thinking of building another with the Toshiba outputs.
Did you do any of the suggested resistor changes or just use Toshibas?
Russellc
I believe its short R11 and use .33 s at R13 and R14.
Yes, Zenmod commented on certain changes, then also I've seen folks who just substituted directly. Just wondering how poster here did it?
Russellc
Russellc
I have received Modu 4U/400 steel cabinettes and will finish my M2s in the coming weeks. What voltage should I monitor during first startup? Over R13 or R14?
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no need to change anything going to Toshiba outputs ....... everything will be in same ballpark , as having IRFPs in place
those mentioned changes were made to increase Iq , if I remember correctly
though , if one is able to make these changes - it's really substantial upgrade to go Babelfish M25 route
most informative illustration is M2 gone Berserk
those mentioned changes were made to increase Iq , if I remember correctly
though , if one is able to make these changes - it's really substantial upgrade to go Babelfish M25 route
most informative illustration is M2 gone Berserk
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of course that generally sound is having same bone .......
up to few watts , there is no difference , simply because currents involved aren't on that level needing any Berserking 🙂
after few watts , there is simply more authority in practically everything , and of course easiest detected in bass part of spectrum
as usual - lesser THD down is giving lesser THD in rest of spectrum
maybe I didn't wrote enough in layman terms ( forgive me , still having that overwhelming sense of proudness , as usual when reinventing the wheel ) , but I believe there is plenty of info in Berserkin' M2 (Babelfish M25) thread ......... in post #59 few impressions of test with usual fifi twosmallbassesand4ohmsoverall speakers ......

up to few watts , there is no difference , simply because currents involved aren't on that level needing any Berserking 🙂
after few watts , there is simply more authority in practically everything , and of course easiest detected in bass part of spectrum
as usual - lesser THD down is giving lesser THD in rest of spectrum
maybe I didn't wrote enough in layman terms ( forgive me , still having that overwhelming sense of proudness , as usual when reinventing the wheel ) , but I believe there is plenty of info in Berserkin' M2 (Babelfish M25) thread ......... in post #59 few impressions of test with usual fifi twosmallbassesand4ohmsoverall speakers ......

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