Moth Audio S 2A3 Amplifiers

4/5 (4 Reviews) MSRP : $3400.00


Product Description

Stereo Power Amplifier - Single Ended - Class A1 Vacuum Magnetic - 3 Watts


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Reviews 1 - 4 (4 Reviews Total)

User Reviews

Overall Rating:1
Value Rating:1
Submitted by Denis vieira a Audio Enthusiast

Date Reviewed: April 15, 2006

Bottom Line:   
This is not a review for their amp bot for the Black Head II moving coil transformer. They said handmade inUK, they sould leave the assembly to the chinese,they do a much better joband for less money, The trans were out af a big blob of glue (clips are to expensive i suppose) and banging on the walls inside They were hold only by the wires. Rca female were all looses and enclosure is sealed with glue not screws. I connected to a tube preamp and a ss preamp same results very loud hum mure like a buzz
these items don't have a ground screw so connect the tonearm ground direct to
preamp but with same load hum. Now if you tried to have somebody to take a look at it, good luck. Everybody seems to have vanished

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Used product for:   Less than 1 month

Duration Product Used:   Audio Enthusiast

Product model year:   2006

Price Paid:    $300.00

Purchased At:   Audiogon



Overall Rating:5
Value Rating:5
Submitted by Cineboy10 a Audio Enthusiast

Date Reviewed: June 15, 2001

Bottom Line:   
Update! If you have purchased the new si2A3 and are interested in doing the modifications I outlined in my previous review, the values of the gridstopper resistors have been changed to 1k ohm. Instead of 6 330ohm tantalum resistors, you will need 6 1kohm tantalums. Of course, you should check on your schematic to make sure. The latest revision that I am aware of is labeled "Revision D."

Also, Shinkoh has ceased manufacture of tantalum resistors. Audionote North America, however, sources their own tantalums. These are still being manufactured and are available at www.audionote.on.ca .

Have fun!

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Used product for:   More than 1 year

Duration Product Used:   Audio Enthusiast

Product model year:   1999

Price Paid:    $1800.00

Purchased At:   www.mothaudio.com



Overall Rating:5
Value Rating:5
Submitted by Cineboy10 a Audio Enthusiast

Date Reviewed: March 11, 2000

Bottom Line:   
Yes, it's true! See the review below. The Moth Audio S2A3 is, indeed, a truly fine amplifier. It's essential, however, to choose your speakers wisely. I've been running mine with a pair of Minitower speakers loaded with Lowther DX-3s. The sound is awesome! Take note, however, that with systems as direct and simple as these, every little thing can and will be heard.

What do I mean by that? Well, things like directionality of cables, for instance. In my system, I use the copper Alpha Core Goertz MI-1 speaker cable. In one direction, there appears to be no bass at all! Facing the other way, the sound is much better balanced. Same thing with interconnects. Again, I and many others can hear this effect. If you can't hear it and don't happen to believe in cable directionality, congratulations! That's one less thing for you to worry about. All the better for you to just enjoy the music. I do hear this effect, so be aware that this phenomenon does exist for some.

By the way, Stereophile gave this a class B rating in their Recommended Components list. Here's a tip that will put it into class A, in my opinion (disclaimer: that is, the sound quality will improve so greatly over the stock unit that it would be hard to imagine that it wouldn't be rated as such. I actually don't have extensive reviewing experience with class A gear). OK, here's what I did:

Number one: get a good grounding in electronics or contact someone who has one. As always, don't start taking apart your gear unless you know what you are doing and are aware that LETHAL voltages are present. These can kill you! Also, a poor or mishandled modification can burn down your house! Yikes! Be very careful! Unplug everything first! It usually voids the warranty, as well. Again, I'm not recommending that you do this, just telling you how it worked out in my system.

Alright, then. Craig and Ron at Moth Audio do a great job packaging this amp. You really do feel good just looking at the owner's manual and the hefty wood shipping crate that it all comes in. Included in the owner's manual is a schematic of the amp. This comes with all the appropriate warnings and is sealed in it's own little section of the folio with sealing wax! This is embossed with the Moth Audio logo. Nice touch.

Looking at the schematic, you'll see that the S2A3 is a direct coupled design. That is, there are no capacitors in the signal path. There are, however, several resistors in series with the signal path. If you look inside the amp, you'll see that these resistors are small carbon composition units, probably Allen-Bradleys. I changed these out.

The amp sounds great already, and a lot of tube enthusiast seem to love the sound of Allen-Bradleys, but after changing these out, I'm of another mind. Take note that the resistor that you choose to replace these with will have a major impact on the final sound. Remember, this is an extremely simple circuit.

The resistors that I chose to use are the Shinkoh tantalum film resistors sold by Steve at Angela Instuments (www.angela.com). These are the same ones that Audio Note uses in their top of the line all silver amps, like the multi-$10K ONGAKU. If you do this mod, you'll need 6 330ohm 1/2 watt resistors. Steve sells these for $6 each.

After this mod, the sound just opened up, became much more transparent and resolved, and the pace became much more rhythmic and bouncy. The amp became much more engaging and fun to listen to. In contrast, the stock unit sounded muddled. It sounded great to begin with, mind you, but muddled and less involving in comparison. With the tantalum film resistors, the sound was still just as warm, only more resolved and lively. There was none of that hardness that a lot of metal film resistors can impart. The increase in enjoyment was major.

Interestingly, just changing out these resistors had more impact than all of the mods that I did on my Audio Note Kit One, which involved changing out the signal resistors to carbon film Kiwame units (no tantalums used in that project), upgrading the signal caps to the Jensen/Audio Note/Angela copper foil paper-in-oil units, upgrading the key electrolitic capacitors to BlackGate standards, and rewiring the signal path with Kimber silver wire.

Oh, and by the way, if you do purchase this amp, try out the new Sovetek 2A3 tubes. These are such a major upgrade over the Chinese ones, you'd be really missing out if you don't. Craig and Ron may have already made these standard on the s2A3s, I'm not sure.

For speaker, I would recommend a good Lowther based system. If you're a bass freak, however, this may not be the best choice for you. I've also had really good success with the Klipcsh Heresies and have heard a lot of great things about the Klipsch La Scalas. Remember that you need high sensitivity ("96db or higher" has been thrown around a lot when referring to 2A3 based amps) and a steady and highish impedence characteristic.

I really do recommend this amp. It really is terrific. Also, in speaking to Craig and Ron, I'd say they really do have a genuine interest in you, the customer. They're very knowledgeable and opinionated and seem much more interested in getting your system sounding good than in selling you something. I love that. For that reason, and for the fact that the make some of the finest amps around, I would definitely do business with them again. I'd also refer anyone who's looking for an system like this to them. They're at www.mothaudio.com. Give them a call. Good luck with your listening!

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Used product for:   3 months to 1 year

Duration Product Used:   Audio Enthusiast

Product model year:   1999



Overall Rating:5
Value Rating:5
Submitted by Kelly Van Arsdel a Audio Enthusiast

Date Reviewed: January 21, 2000

Bottom Line:   
It's a honor to be the first to review the Moth s2A3 because it really is an extraordinary product. From the handmade wooden packing crate to the amp itself everything about it is of exceptional quality.
The amp itself is a class A vacuum tube single-ended triode design that uses a 5AR4 fullwave rectifier, two 6SL7
drivers and two 2A3 output tubes. The chassis is both gorgeous and substantial. It weighs forty lbs and is constructed of anodized aluminum and cold-rolled steel.The fit and and finish are nothing short of phenomenal. The pride that Moth builds into their product is obvious as soon as you get the product into your hands. Simply flawless fit and finish from front to back, inside and out. The amp features a volume control, headphone jack, and a pair of Cardas inputs for a single source. The speaker binding posts as well as the solder used in the construction are made by Cardas as well. The amp is handmade using point to point wiring throughout. The circuitry is very simple with no capacitors in the signal path.
So how does it sound? In a word, breathtaking! It makes you listen intently to recording you've listened to for years as the Moth extracts nuances and sound that you have never heard before. It may sound trite but everything sounds like you are hearing it for the first time. Nothing hides from it! Very revealing without being fatiguing. The bass the thing makes is just amazing! It goes deep and detailed.
Bass has so much dimension to it as I have never heard before. Not just a bunch of thuds and thumps that your garden variety solid state amp produces. It is the best bass I have heard from any amp in my life.
The mids as expected are glorious. Horns sound simply like horns with all the life and vitality that one would expect from a live performance. Stringed instruments resonate with life. The highs are very detailed unlike some other tube products I have heard.
Overall, it is the finest amp I've ever encountered. The only caveat that I'd offer is that your speakers need to be 96db efficient to mate properly with the Moth. If they are you'll find yourself in total amazement at all the power and majesty and room-filling volume it's three supreme watts can make!

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Used product for:   Less than 1 month

Duration Product Used:   Audio Enthusiast

Product model year:   2000




Reviews 1 - 4 (4 Reviews Total)

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