Official M2 schematic

[Zen Mod]

well,I'm still trying to make distinction between mV and MV , even if I'm less often having contact with later



which outputs you're using ?

regarding offset - everything up to 30mV (either +/-) is practically nothing , which means OK

do not bother with normal fluctuations , resulting from change in temp. , because of open/closed lid

 

[Russellc]

well,I'm still trying to make distinction between mV and MV , even if I'm less often having contact with later



which outputs you're using ?

regarding offset - everything up to 30mV (either +/-) is practically nothing , which means OK

do not bother with normal fluctuations , resulting from change in temp. , because of open/closed lid

I'm using the ones in Tea's group buy, this, IRFP240PBF Vishay Semiconductors | Mouser

And a NOS Harris IRFP9240 that tea is supplying for his group buy.

Russellc

 

[Russellc]

Its in system now "reheating" so far, like every Pass DIY piece I have made it is DEAD quite, even on horns...well, half horn half box Econowave.

Russellc

 

[Zen Mod]

so , let us now what's level of pleasure

now , and in a week or so

 

[wdecho]

Good news RussellC. Yes tell us first impressions compared to your recent F6 build.

 

[Russellc]

Well its playing music....warming up with a little FM. Another 30 mins and I'll start in in earnest, listening to it break in with higher quality sources.

Then upstairs to the vinyl rig, which is where F-6 resides now.

Russellc

 

[Zen Mod]

well , F6 s ....... F6

while M2 is ........ Mighty Mouse of amps

 

[wdecho]

well , F6 s ....... F6

while M2 is ........ Mighty Mouse of amps

 

[Russellc]

First notions are that it is a little distant and way laid back with not tons of bass. This is already starting to change, bass much better, less laid back which is good. Needs more time like F-6 did.

Soundstage expanding more, better and better. This parts list I used:

https://docs.google.com/spreadsheet...kL0s0l0HVg6NHbedx5RN8/edit?pref=2&pli=1#gid=0

Russellc

 

[Russellc]

While M-2 had very good results with horns, things got very interesting upstairs on vinyl system and two way mini monitors.

Ahmad Jamal's Rossiter Road was simply hair raising. May have a new favorite Firstwatt amp!

Russellc

 

[jborden]

Its in system now "reheating" so far, like every Pass DIY piece I have made it is DEAD quite, even on horns...well, half horn half box Econowave.



Russellc

My M2 displays some hum with speaker sensitivities >100Db or so.


Room treatments for headphone users

 

[wdecho]

My M2 displays some hum with speaker sensitivities >100Db or so.


Room treatments for headphone users

Nelson has made the comment that a slight amount of hum might be present because of the input transformers. At least I think I remember reading this in the past. I have LaScala's and mine is quite but it probably depends on your horns sensitivity. You may try shielding the input transformers or maybe checking your grounding scheme.

I awoke this morning with anticipation of reading your review of this M2 Russellc and was disappointed earlier by not seeing anything but I guess you were too busy listening last night to bother posting anything. I understand. This amp has reached the top of my FW builds as well.

 

[franzm]

Wouldn't a belly-belt over the input transformers help against hum? At lest it's easyer to build then a magnetic shield.

 

[Dennis Hui]

It seems you guys are having a lot of fun with the M2. Has anyone compared
different output devices?

Cheers,
Dennis

 

[generg]

Liveliest presentation with FQA, more rocking.
IRF more well tempered.

Over all most convincing SK1530/SJ218 combo, but only with not current demanding speakers.
Do not know why.....

 

[wdecho]

Just a foot note about my 85mv dc offset. I replaced R6 47K resistor with 42.9K resistor and zero'ed my offset without a problem. I had to series a 39K and 3.9K because that is all I had. I did it without removing boards but future builders would be wise to leave R6 and R7 proud of the boards with some extra leads where it will not be a big problem replacing resistors. I sealed it up this morning as well.

 

[Russellc]

Good news RussellC. Yes tell us first impressions compared to your recent F6 build.

On vinyl rig, like zenmod said...F-6 is F-6...this amp is mighty mouse.
Best Firstwatt so far to me.....

Russellc

 

[Russellc]

Liveliest presentation with FQA, more rocking.
IRF more well tempered.

Over all most convincing SK1530/SJ218 combo, but only with not current demanding speakers.
Do not know why.....

I have a very few sets of SK1530/SJ218, which FQA devices and are they available?

Russellc

 

[WalterW]

I guess you mean 2SK1530 / 2SJ201 ?

 

[Russellc]

My M2 displays some hum with speaker sensitivities >100Db or so.


Room treatments for headphone users

What did you use for input wire? Teabag had a little hum that went away once he replaced input wiring with shielded cable. I used 2 short runs of Silver Sonic BL-2 interconnect cable, which is shielded...no hum.

Russellc