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Calling Moth 2A3, s2A3, si2A3 Owners

post #1 of 13
Thread Starter 

As Craig has plans to re-introduce an updated version of this amp, I am wondering how well the older versions drive the new breed of planar-magnetic headphones and what headphones you have found to be most suited to this amp?  I think Craig is also looking to develop a heater supply that is less prone to hum. Do you have any hum issues with your cans?


The pic is of the old S2A3 version.



Moth 2A3 Headphone amp

post #2 of 13
I owned two different versions. The original s2a3 pictured above and the tweaked version si2a3/45H.

The original s2a3 had hum with low impedance as the power transformer was in the same chassis as the output transformers which due to proximity picked up some low level hum. Otherwise it sounded great.

The si2a3/45H placed the power transformer in an external chassis, and coupled with power supply and various cap improvements, was dead silent with low impedance cans. It also sounded great.

I preferred the two above with my grados, some of the best sound I ever achieved.

Never had the chance to hear the new planar stuff but my gut tells me with 2a3 power on reserve it would have been more than plenty and would have sounded beautiful with the lcd2 and may have done a decent job with the heavy duty HIfiman stuff.
post #3 of 13



Edited by thinker - 1/19/14 at 1:13am
post #4 of 13
Thread Starter 

Thanks.  Craig was looking at some new OPTs when I spoke with him, but i did not know about the external box for them. I'll ask him.  I hope someone with the si model replies. I wonder if he'll bring it to RMAF?  I can't attend, but some members should be able to give listening impressions, if he does.

post #5 of 13
Thread Starter 
Originally Posted by thinker View Post

i have the oldest  2A3 and no hum issues at all.It drives easily all new planars.Sound HD-800 9/10,AKG -702 with SAA endorphine cabling 10/10,LCD-2 9/10  and the new OTL Ederer with HD-800 10/10,AKG-702 9/10 LCD-2 10/10



TThanks.  This is exactly what I wanted to know.  Who built the amp in the wooden chassis and what are the typologies and tubes?  The power tubes are easy to ID, but not the driver or what I guess are the rectifiers, unless you are driving with DHTs!





post #6 of 13


Edited by thinker - 1/19/14 at 1:13am
post #7 of 13
I have a Si2A3. Stock, though I understand it was modded (at the factory) to bypass the speaker ouput when a headphone is plugged in.

I have not had the opportunity to run it with planars, but it does a phenominal job with everything in my collection. I love the HD-800 with it and it did great with all the headphones I sold (HD-600, HD-650, K-501, RS-1, DT-880) save for the K-701 which never sounded good no matter what I plugged it into. It does an amazing job with the K-1000, though I connect it to the speaker taps.

I'm very glad to hear Craig is bringing a new version out. The 2A3 is almost perfectly suited to headphone listening. I don't talk too much about the Si2A3 (or other OOP stuff I have) because I don't like encouraging the "I have something better than you and you can't buy one" attitude that shows up around here. It'll be nice to recommend the new version - I think a lot of people will go nuts over it. (Not to take away from the greatness of the Zana Deux, of course. That still might be the best amp on the market.)
post #8 of 13


Looks like there's not so many of us  out there. Not surprising really, I'm sure Mr. C didn't sell boatload. 


A few years back I scored my little beauty, but like the others have never ran her to an electrostatic. I was wondering how they would work with the Lcd2 and thought of picking them up to give it a whirl, but then my right channel died. Dead as a doornail.


I'm not in a position to overhaul it myself so I need to find someone in Toronto that can save her life, but not ruin her as they do so. She's serial #10, so I assume very early in the production run. Might need more than the channel repaired, but if replacing dry caps, re-biasing et al. is in order it's hard to imagine how much better she'll sound, but I think it's definitely worth a go.



post #9 of 13
Oh yes, absolutely get it fixed.

See if there is an amateur radio club nearby. Up there, it's the Radio Amateurs of Canada (www.rac.ca). Your local club will have at least one person who tinkers with tubed radios. They will know how to fix it and probably won't charge you much.

Did you get the schematic with yours? It came with them. If you don't have it, ask Craig for a copy.

Too bad you're not quite in driving distance. I'd be happy to help you fix it.
post #10 of 13

Uncle E, let me know if you are interested in listening to the Super 7 later.


I don't even have it yet, but would enjoy sending it to you for your comparisons (have not yet heard Zana or Moth).


Damn my curiosity/obsession!!!  redface.gif


After the Bay Area Meet in Feb.?


I'm excited to be on the pre-order...the prototype sounded great.


And, thanks again for being on H-F.  (When I meet up with other Head-Fiers, I always say that I'm glad you're here- doing what you do!)

post #11 of 13

I don't know if I'll free up until early 2012, though. I'll start a new job within a week or so and might buy a house in the same timeframe. smily_headphones1.gif Plus we're trying to finish off some stuff for the family biz, then there will be holidays and a week of vacation.

But I'd be happy to share the Zana and Si2A3. I might be able to knock off the Barbour Brute Force amp that has been about 80% complete for two years and possibly the Ciuffoli SESS 417A and Dynamid amps, too.

I haven't been to a meet since CanJam '10, so I'm eager to get back out there and see everyone. And there are several people I really want to meet, too. Once things normalize, I'll be hitting all the San Diego, LA and Phoenix meets. And if the house goes through, I'll be happy to have people over.
post #12 of 13

^We'll keep in touch!  bigsmile_face.gif


Any recommendations for a good tube-tester, Uncle E?


(Would be good to have a nice one for California members and also have at the next Bay Area Meet for people to check their collections.)

post #13 of 13



I listened of my new purchase an Moth S2A3 with rectifier tube on top since 1 weeks.

I owned many high amp like Woo WA5, Balancing Act 300B, DNA Stratus and 2A3MKIV. 

The amp was completely cleaned, checked and recapped. I use Sylvania or RCA 2A3 dual black getter, Amperex GZ34 and Roger ECC35.

IMHO it's a marvellous amplifier. Honestly I didn't like the 2A3MKIV and DNA Stratus with the HD600 as the sound were too ethearal, thin with tizziness in treble.

The Balancing Act where smooth and fluid but a bit distant, I didn't have the best tubes for it so I cannot hear him at his best. The WA5 was a bit harsh and overpriced.


Hearing the HD600 on the Moth it's hearing another headphone, more body, heft, smoothness and openess. The Moth is a bit more intimate sounding in the sense less distant than the others amps I owned. In the same time it has more openess because each sounds has more depth and intensity.

To sum up it has an textured thick sound with solid bass foundation, speed and heft with smoothness that removes tizziness. Also it has unique lively and vibrant sounds that let you to travel into the music.

Edited by Hun7er - 4/12/15 at 2:27am
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