Friday, October 1, 2010

[REVIEW] JDS Labs' cMoyBB v2.02

I have had and certainly heard a few variation of cMoy before, but this is the first cMoy I have heard with a bass boost switch. cMoy is itself an fairly old design, first made and schematic published by the well respected Chu Moy @ It is the portable headphone amp that invented the whole portable amp market, which is something we ought to thank Chu Moy for. The cMoy with Bass Boost v2.02 by JDS Labs that currently under review is however said to be the more advanced version of the original design. The obvious question is of course, how good can a cMoy be?

cMoyBB v2.02 comes in a mint tin, as most eBay's cMoys do.

The bass boost switch is in the middle. Both volume pot and the headphone jack (left jack in picture) are acting as power switch.

Build quality wise, this cMoy'BB' is pretty close to top notch for what essentially is a hand-soldered, DIY'ish product. The only other DIY product I have ever seen that has a better build quality are the PenguinAmp series, made by the same guy who are currently running Headphonia / HeadStage (maker of the Arrow 12HE amp).  As you can see from the picture, the cMoyBB is built on a professional PCB (Printed Circuit Board) instead of a more rudimentary protoboard. If you are the type who likes to DIY, you can purchase the PCB from JDS Labs and make the cMoyBB yourself. The PCB is around $6. The whole amp, fully assembled and with battery, is about $70 + shipping (or $75 + shipping if you buy from eBay).

As far as the sound quality goes, cMoyBB is indeed the best cMoy I have heard so far. I rolled the same opamp used on cMoyBB (OPA2227) into my other cMoy, the Jaben cMoy (which I soldered about 2 years ago and I always thought it to be pretty decent sounding), and compared it to the cMoyBB. There is almost no comparison - cMoyBB is simply a class above Jaben cMoy. But given I only paid around $20 in total for the simple Jaben cMoy kit and soldered it myself, I guess the result is to be expected.

cMoyBB next to an old, first gen. Penguin amp. It is pretty obvious why it is called a Penguin amp.

Left: Penguin amp; Right: cMoyBB v2.02. Penguim amp is a modified cMoy as well.

So how good cMoyBB is when compared to a similarly priced amp, said FiiO E7, which is about $85 with free shipping? Fed by Sansa Fuze's line-out via my newly mod'ed FiiO L6 LOD and listened with HifiMan RE0 and Etymotic ER4S, cMoyBB sounds more spacious and airy, bass note is full of impact but doesn't quite have the texture to go alone (even with bass boost on). It has better detail, but also sounds just a little sibilant. E7 is warmer and smoother, vocal is sweeter and bass, though can't be boosted to the same level as cMoyBB, still has better texture. Overall the performances are comparable between the two, though it is worth to note that cMoyBB has higher gain than E7. For example, E7's volume 30/60 is roughly equal to 9 o'clock and a half on cMoyBB volume pot.  Two things that I like about cMoyBB over the E7 are: 1st, cMoyBB bass boost is better than E7's in the sense that it not only give a big bass boost, but also adds warms to the sound and does not reduce the treble much. It works fantastically well with analytical sounding IEM such as HifiMan RE0 and Etymotic that I used for this review. 2nd, the opamp on cMoyBB is roll-able (exchangeable), which means it can be improved (or simply tuned differently) if you are willing to spend a bit more on new opamp. In fact, my cMoyBB is not on the default OPA2227 anymore. So in short, if you are only interested in amping and nothing else, cMoyBB is a probably a better choice. But if you ever need a DAC, then E7 is still the bigger bang for the bucks as a complete package.

Now let's talk about opamp rolling on cMoyBB. The default OPA2227 is pretty good sounding and definitely better than the previously popular cMoy-opamp-of-choice, the OPA2134. However as mentioned before, the downsides of OPA2227 on cMoyBB are it sounds just a little sharp and doesn't quite have enough bass texture. I tried a few other opamp that I have in stock, mainly OPA2134, OP275, AD8066 and AD8620. Personally I find both AD8066 and AD8620 to work out really fine on cMoyBB. They have a more textured, better layered sound and can produce detail without being sibilant. The other main difference is the both AD has a warmer sound while the OPA2227 is colder in comparison. With the AD8620, I reckon cMoyBB is almost as good sounding as many $100+ portable amp. It certainly is better than my iBasso T4 and gives the  T3D a run for its money. Still, as good as cMoyBB with AD8620 is, my cMoy2 remains the best DIY portable amp in my collection.

From left: cMoyBB v2.02, cMoy2, Jaben cMoy.

Do note that AD8066 and AD8620 are SOIC8 package so they won't fit on cMoyBB's DIP8 socket without an adapter, such as those from BrownDog.  Premounted (on adapter) AD8066 and AD8620 can be found online though, but they are not cheap - roughly $15 and $30 each. If you do get them, you will also need another DIP8 socket as well, to create enough clearance in space since there are 8 resistors mounted too closely to the original DIP8 socket. Without an extra DIP8 socket, the adapter might not get enough space to go in. Also, if you use a DC adapter to supply extra juice to the cMoyBB, you need to be sure that whatever opamp you are using can accept the DC voltage you supply to the amp.

Overall, I am impressed and pretty happy with the JDS Labs' cMoyBB v2.02. Sure it is almost twice as expensive as most cMoy on eBay these days, but it does have the quality as well as the performance to justify the price tag, and maybe even the claim of best cMoy in the market.


Anonymous said...

Hi clie, I really love your blog. I own an iPod Touch and Sennheiser IE6 and planning on buying FiiO L9 and an amp. I'm quite confused for the amp because I'm not really sure which amp suits me the best. I like to listen songs with big bass but I also like acoustic and classical stuff. What amp shoud I get? FiiO E11, cmoy, or maybe other amp? Thanks a lot

Tai / ClieOS said...

For IE6, I think cmoyBB might be a better match than FiiO E11, especially consider the genre you are listening. Do remember to get a LOD.

Anonymous said...

How about IE8? I may also buying it if the price is right. Or is there any better suggestion for in-ear?

Tai / ClieOS said...

IE8 probably pairs better with cmoyBB as well.

Anonymous said...

Thanks a lot!

Anonymous said...

If i want to change my opamp, which one is better? AD8066 or AD8620?

Tai / ClieOS said...

Both will sound better than the stock opamp (OPA2227), but AD8620 will be more refined than AD8066. Note though, AD8620 on battery will be underpowered. It still sound really good but only when it is used with wall adapter that it will sound really good.

Anonymous said...

can this cmoyBB handle balanced TRRS plugs like the Zero/262/272 , without the extra adapter?

Tai / ClieOS said...

As far as my cmoyBB v2.02 goes - yes, it can be used without the TRRS adapter though RE262 (I think) and RE272 don't use TRRS adapter anymore, but TRRS extension cable. So it really doesn't matter if cmoyBB takes TRRS or not for them.

Andi said...

Hi, thanks for your interesting review, i think of getting the AD8620 now that you mentioned it. Do you know what Voltage the original OPA2227 and the AD8620 can take maximum when powered with a DC Adaptor? I have a 9V - 24V DC adapter with a switch; The manual said a DC 9V-24V is okay (it even mentions to use one with 18+V, because it increases dynamics, but i'm scared to fry it.) Thanks


Tai / ClieOS said...

They can both handle the 24V (which split into +12V and -12V), but I won't recommend setting it that high, especially if the adapter isn't regulated. Personally I think 18V or so is more than enough. You can even set it as low as 12V.

Anonymous said...

Hello, how about CMoy Tri Channel ?
which one is better ?
for transparation and separation.. detailed and staging.

thank you

Tai / ClieOS said...

Never heard the Three Channels cmoy before. But from the picture floating around Head-fi, it looks very much like a cmoy2 clone.

Devirdaim said...

now it is more complicating to me. so what is the best cheapest (<50- max60 usd) amp to add some fun (sub bass quantity, without loosing treble detail) for my lovely sounded RE0

Tai / ClieOS said...

Choices are pretty limited at your budget - but cmoyBB should fit your need as well. It has everything you need and you can find a used cmoyBB around/under $50. Otherwise, a FiiO E11 might do the trick as well.

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