Official M2 schematic

[JR_W]

I'll call them. I can use any zip code in TX and get the same message.

 

[xrk971]

Try ordering just one. I think two exceeds weight limit of USPS priority mail. You actually only need one of those for the M2. I have the same one and it's not lacking in power at all.

 

[JR_W]

I called and ordered them over the phone - their shopping cart is messed up at the moment.

I'm building 2 amps, one with Toshiba outputs and one with Tea Bag specials.

 

[massimo]

I'm building 2 amps, one with Toshiba outputs and one with Tea Bag specials.

That's very interesting! Pls keep us updated on the results. I'm planning to build an M2 with the big Toshibas in the next future

 

[xrk971]

Which Toshiba outputs are we talking about?

 

[JR_W]

2SK1530/2SJ201

 

[Bangla H]

2SK1530/2SJ201

That is my choice too, but must order two big heat sinks. I will not pull out my fine playing
Aleph J to fix this one.

 

[Soundhappy]

Here's a picture of the layout in progress

@ BDP

Do you put into circuit jfet's BL grade with Idss around 8mA or they are GR pairs ?
Greetings

 

[BDP]

Yes, they were between 8 and 9 mA Idss. I still have a stash from a few years ago, but my 2SJ's are running low, 20 left. Everything I build has them.

Haven't had time to do more. I have a coffee can I will cut up and cover the toroid.

 

[Soundhappy]

I have a coffee can I will cut up and cover the toroid.

Why i ask about jfets ? Well i never see 2SJ/SK with leg's shape like on your photo but if you say is ok..
Yeah coffee can !
Good idea let's try
Best regards

Post scriptum: On my bench few 10 R wire wound's for jfet buffer who stuff nicely on pcb's
but they are magnetic and pretty close to Edcor...finaly my decision is not to use them for M2.

 

[BDP]

Those are the 2sK's. Cut and Reel type package. The transconductance measures good from a couple of data points.

 

[woody]

For us in the U.S.A. where is the best place to get those transformers ?

 

[needtubes]

For us in the U.S.A. where is the best place to get those transformers ?

Which transformers? The input transformers are from Edcor in Arizona and most people in the US use Antek power transformers. Are you referring to some other transformer?

 

[woody]

Thanks I have the power transformers I just need the input transformers.

 

[needtubes]

The input transformers are here. Just be sure to get the "600 to 15k" and not the "15k to 600." One user from a while ago accidentally selected the wrong one from the drop-down menu and had to order twice.

 

[Soundhappy]

Those are the 2sK's. Cut and Reel type package. The transconductance measures good from a couple of data points.

Was year ago i stuffed by mistake with GR grade jfets all have the same legs shape so today i am always alarmed by see this cut & reel package.
Great they are BL ones

I see some amateurs use copper flexible rubans for shield do you know is efficient ?

Get this vintage LUX transformers they are dual magnetic shielded A.F
and perfectly balanced hum bucking windings version.
For my diy M2 i use Edcors anyway just must shielded them.

 

[Dennis Hui]

I was hoping someone with a factory M2 might stick their DVM on the speaker terminal and give us a number?

BDP

With input interconnect shorted, I measured about 0.32mV AC across an
8 ohm load.

Thanks,
Dennis

 

[BDP]

Thanks for the measurement Dennis. My layout is comparable to the factory units. I guess I will have to call it good.

An update on a couple thing I tried.

A cover over the transformer, that made no difference.The shield on the transformer is doing its job.

I mounted some thick steel plates to the bottom plate that come up to cover the front of the Edcor transformers and that dropped the noise a little more.

Now I am about 0.26mV AC on the speaker outputs.

BDP

 

[Full Range]

Hi folks a quick update in between my busy schedule
I have constructed some fully enclosed MuMetal box surrounds for the Edcor transformers

Next week I'm away overseas on work related business, and upon my return I will construct the Tirodial enclosure
Soon after I will swap over the newly arrived JFets

NOTE - Haven't sound tested for any changes as yet

Fingers crossed, if I can steel away some hobby time prior to my flight I may just get the Tiroidal enclosure finished

Until the next update instalment
FR

 

[DIYspaceW]

Hi guys,
I dont know if someone of you also observed that his M2 clone is mid bass and bass weak! Or am I missing something! My configuration is 180.000 uF per rail dual mono in separate cases. Is there any way to tweak for a little more bass!

Thanks.