[Beefy]

Very nice Linuxworks!

I'd love to hear some listening impressions compared to your B22. I'm currently torn between building a second M3 and re-casing it with my current one to go balanced, or building something entirely new......

 

[linuxworks]

would I be tarred and feathered if I said I liked the m3 as much as (or more) than the b22?

the 'build JUST enough to do the job' engineer in me likes the m3 better. I think its JUST enough for a phones amp and not an obscene amount of overkill (lol).

the m3 also allows more 'on the fly' gain setting. that's VERY practical! on my photo, you can see some small red and white jumper shunt blocks in the middle of the m3 board. that's an intercept point for bass boost OR variable gain! what I'm thinking of is having some latching relays (1 or 2 bits worth) to select 2 or 4 levels of gain. true gain settings; in addition to a regular attenuator for input. that really lets you tune the S/N based on whether you're driving high-z or low-z cans. will probably have a controller cpu do the setting for me, too (lol).

I may end up using the b22 as dual monoblocks for my spkrs (only) and this m3 for phones listening.

 

[Beefy]

Quote:

Originally Posted by linuxworks /img/forum/go_quote.gif would I be tarred and feathered if I said I liked the m3 as much as (or more) than the b22? the 'build JUST enough to do the job' engineer in me likes the m3 better. I think its JUST enough for a phones amp and not an obscene amount of overkill (lol).

Not at all! You hear what you hear, and you build whatever floats your boat. My practical nature tends to agree, and I seriously wonder whether my ears are good enough to tell the difference - or whether I would care anyway.

Mind you, in my case building a balanced amp doesn't exactly fall into the non-overkill camp......

 

[grawk]

I preferred my balanced m3 to any b22 I'd heard, too

 

[rds]

Quote:

Originally Posted by TeraHz /img/forum/go_quote.gif Well there it is, about a month later: ... Sounds great with both my uFonken speakers and SR80 phones.

Why did you decide to add the zobel?

 

[Emooze]

Dramatic pause, makes everything better

 

[TeraHz]

Quote:

Originally Posted by rds /img/forum/go_quote.gif Why did you decide to add the zobel?

It is advised by the designer:
Quote:

Originally Posted by http://www.amb.org/audio/beta22 ... if the amplifier is intended to drive speakers, the Zobel networks ... should be connected across the output binding posts of each channel to compensate for the inductive speaker load. Without the Zobel network, the amplifier may become unstable under certain conditions.

On a side note, my dpdt switch stopped working on the headphone side after the second switch now I only have speaker output working...

 

[linuxworks]

zobels can only help and not hurt, right? I have one on my b22 and I do drive spkrs with it, but when I'm driving phones I don't notice any 'bad' effect. I think it can only help, so why not add it.

 

[MisterX]

Twins?
(there is a Mini3 in the "other" case)

 

[mattcalf]

Awesome build TeraHz and MisterX.

I find all this talk of the M3 being liked better intriguing.. still I don't think I could resist a B22.

 

[ShinyFalcon]

Indeed! I have the sudden urge to revisit the M³, now that I have a σ22.

I really like those γ2 panels. All the ports on the front makes the γ2 look strange, but now maybe my leftover γ1 board will have a purpose after all

 

[pixeljedi]

Quote:

Originally Posted by MisterX /img/forum/go_quote.gif Twins? (there is a Mini3 in the "other" case)

γ2! Drool! Very nice!

Out of curiousty, how did you mount the Mini³ board in that larger case?

 

[ShinyFalcon]

There is one hole for a screw where the battery lies. I'll say that he placed the board into a slot for support, and held the board in place using the hole where the battery lies. You could probably use the hole on the LM317L as well.

 

[MisterX]

The circuit board is held in place on the front by the nut on the pot.
I cut a piece of flat aluminum stock that fits in the top slot of the enclosure to support the back and then drilled a pair of "mounting holes" in the circuit board.
Attached the "bracket" to the board with a couple of screws, nuts and standoffs and the whole thing slides right in.
It was kind of a PITA but I did not have to drill any holes in the extrusion that way.

Maybe will take some pictures the next time I remove the panels...

 

[pixeljedi]

Quote:

Originally Posted by MisterX /img/forum/go_quote.gif I cut a piece of flat aluminum stock that fits in the top slot of the enclosure to support the back and then drilled a pair of "mounting holes" in the circuit board.

Very creative. I like. How much room in the back did you end up getting with that extra space? enough for RCA input?