Official M2 schematic

[brianco]

What speakers are you using? What is their efficiency?

 

[Zen Mod]

mine is 66mF per rail , dual mono,sounds perfect

you have more info , pictures ?

which output mosfets ?

 

[DIYspaceW]

What speakers are you using? What is their efficiency?

I use full range sonido, horn loaded and infinity quatom 5...With mcintosh Ma 6100 I have greater bass fundament for comparison...

The transistors are matched toshibas Mosfets and jfets...

 

[DIYspaceW]

Full range are 93dB (5 ohm) and Infinity 89dB (4 ohm)

 

[Zen Mod]

what preamp with M2 ?

first time I hear ( and I can't even think ) of bass deficiency , when M2 is in question

 

[DIYspaceW]

My line stage is 6e5p choke loaded!!!

 

[Zen Mod]

try connecting M2 directly to source

in case od PC playback , set volume in player to min, power up M2 , then listen

preamp need to sound better than that ......... and only then you can blame (any) power amp for flaws

 

[DIYspaceW]

Already done...preamp sounds and measures ok! I assume speakers missmatch and room specifics...also can I raise power lowering source resistors to 0.39R...

 

[Zen Mod]

clarify that 0R39

 

[DIYspaceW]

Right now I have 0R5 as source resistors for Mosfets but thought to lower for more power...
I have solved the bass problem a little bit, I have optocoupler volume control and this was the source of problem...
So far its interesting that M2 is driving the Infinity quantum 5...

 

[Zen Mod]

leave it as Nelson made it

 

[Soundhappy]

@ Diyers

By copper shield foil i mean like on this one.
M2 need care protect from all magnetic components interaction.
Experiment & find efficient solutions My best

 

[Russellc]

M-2 questions, Toshiba resistor change and pand preferred J Fet idss

Have completed another set of Tea's M-2 boards for a Toshiba output version and have a couple of questions.

What is the ideal idss for the Jfets used in M2? I have a set from the store, BL grade,and I have a few sets from High 8 to low 9 idss on hand... and secondly,

As these boards are already assembled with stock values, how much of a problem is NOT changing R11 to .1 R (from 100R) and R13 and R14 to .33R (from .5R) as Zen and others suggested? (See posts #891 and #902) Or just R11 changed and source resistors left at .5?(with Toshiba mosfets)

Thanks,

Russellc

 

[needtubes]

What is the ideal idss for the Jfets used in M2? I have a set from the store, BL grade,and I have a few sets from High 8 to low 9 idss on hand

Those will work fine. The JFETs see the 24V rail, so you want to keep the IDSS under 10mA to keep them running cooler.

I don't have any experience with the Toshiba MOSFETs, so cannot comment on that.

 

[Zen Mod]

optocoupler thingie will set Iq , even if you use two submarines as outputs , as long they (submarines) are having proper governing electrode

so - Toshibas , IRFP , 2SJ/2SK ,FQP/FQN , whatever , even bipolars will be biased at approx. 1A2-1A3

edit : that being with original Rs values (0R47)

if you decrease Rs values , Iq will rise in same amount/percentage

 

[Russellc]

Anyone have any feelings about bass output when comparing IRF type mosfets with the Toshibas? Same, less, more? (as far as M2 is concerned.)

Russellc

 

[Zen Mod]

Have completed another set of Tea's M-2 boards for a Toshiba output version and have a couple of questions.

What is the ideal idss for the Jfets used in M2? I have a set from the store, BL grade,and I have a few sets from High 8 to low 9 idss on hand... and secondly,

As these boards are already assembled with stock values, how much of a problem is NOT changing R11 to .1 R (from 100R) and R13 and R14 to .33R (from .5R) as Zen and others suggested? (See posts #891 and #902) Or just R11 changed and source resistors left at .5?(with Toshiba mosfets)

Thanks,

Russellc

just leave everything as in original
my comments from posts mentioned above were strictly to Generg , regarding Iq increase, in fact , decreasing value of Rs , so decreasing deeneration , so increasing xconductance

Anyone have any feelings about bass output when comparing IRF type mosfets with the Toshibas? Same, less, more? (as far as M2 is concerned.)

Russellc

I believe Generg (Golden Ear ,officially) will have most to say

comparing to him , it seems as I spent several years playing with elephants , while their fave game was farting in general direction of my ears

 

[Russellc]

Well then! Elephants notwithstanding, I am pressing on. I guess I will use the 8.8 or 9.3 idss sets, I assume the store set of Jfets I have, which are BL could be within spec, yet over 10 idss, right? Thinking BL goes up to 12? I would like to try the store set, all I have used on previous builds were Toshiba J fets, but alas, supplies dwindle!

Russellc

 

[Zen Mod]

if you have higher Idss range ones (more than , say , 8mA) , just check their current in circ , measuring voltage drop across R3 and R4 (ref. to post #1)

increase R3 and R4 if needed

 

[dimkasta]

I'm half way through the thread. Really tempting stuff.

I have a noob q about the schematic.

How Q1's gate receives its signal? Through C3?
That's why mighty ZM liked the 1uF across it? And value was chosen because biggest silmic is 3300?