cMoy or Chu Moy is one of the most popular DIY amplifiers because of their easy to build with highly customizable and low cost designs. Over the years, there are many variants of cMoy including the JDS Labs’s cMoy design which have being heavily redesign over the original cMoy amplifier, other designs that use wire with gain which doesn’t have PCB boards (a direct wiring designs) and even cMoy that have been redesigns to use tubes.
Designs
The one that I’m going to be reviewing now is the JDS Labs cMoy BB V2.03 which as I said before has being heavily redesigned and improved over the original version thus given the name V2.03 for version 2.03. Given my lack of experience with different version of cMoy, I will not be comparing them over the other design. However, it is said that the JDS Labs cMoy is currently one of the few tops cMoy design that is available on the market. Currently the latest version of JDS Labs cMoyBB is the V2.03R which as stated in the version numbering is the same in designs as my current version. The only changes are the integration of the charging circuit into a single board as opposed to my version that has a separate port for charging which doesn’t support used while charging. It’s very rare to have a cMoy that can be recharged from the amp directly and this is one thing that sets the JDS Labs cMoy apart from the other designs. After all you are using a 9V battery that always have to be replaced or recharged, so why bother about taking it out to replaced or recharging it when you can charged it directly from the amplifier with the JDS Labs’ cMoy BB.
Although the JDS Labs cMoy support charging or even powering it directly from the wall to give it a better output and smoother response and avoiding the needs to replace or recharging the batteries, they did not supply the wall adapter for a good reason. Our world is so wide and every country would have different voltage ratings on top of different pin designs which make certain wall adapter to be unable to work on certain country. So instead of increasing the cost of an already good sounding amplifier, John has provided the specs instead to help you choose the correct adapter for your country. The Specs and further details can be found here. I would suggest getting a regulated power supply which gives a stable voltage supply as given by the manufacturers rather than the unregulated power adapter. In an unregulated adapter designs, a ratings of 9 volts in the label given by the manufacturer might in fact be higher than 9 volts. And with a 12 volts settings (Some can choose voltage setting) you can get up to 21 volts or more. And if you have a sudden spike in the power you might exceed the recommended 24volts DC and blow the internals. And also please take note, cMoy only supports up to 24v DC ratings and not 24v AC. So please be careful when purchasing your adapter.
Besides that, the cMoy also comes with a circuit that will auto shut down when it does not detect any inputs in the headphone out. This design helps the cMoy saved battery when you have forgotten to shut it down after unplugging your headphone. Silly us, but sometimes we do makes mistake of not shutting down our things when we are in a hurry or when we are busy. The battery lives out of this cMoy can last from 8 hours to 20 hours depending on loads. As for me, using the rechargeable Tenergy 9V from JDS Labs gives me a total of one week time before requiring me to recharge my battery. That’s a good time considering I can at times used until 5 to 6 hours a day.
I’ve heard some people on my local community that complains about the stock version would cause distortion or not powerful enough to power those lower ohm and low sensitivity headphone. The good news is that, John from JDS Labs can help you customize the Cmoy according to your specific headphone/IEM. However, if you have both low impendence (Ohm) and high impendence headphone at the same time, it is suggested that you purchase the stock version. Tough the stock version won’t excel at either powering a low impendence and low sensitivity headphone such as AKG K701 or the high impendence headphone such as those rated 300ohm headphones, they can still do the job fairly well in giving you just enough juice to get you going. So if you have only either side, try to specified the headphone that you have when you purchase the Cmoy, and John will help you customize it. And if you have both high and low impendence headphone, then ordering the stock version will be a better choice.
The cMoyBB comes in a very nice Altoids tin with a Curiously Strong Mint flavor that has total calories of 10 for three pieces. So I guess listening it for too long might not get you increased your weight. Okay, quit the bad joke and come back to serious matters. The tin that I get is in a flawless condition though John does not guarantee that all the tins that you get will be flawless. Well who cares it looks flawless or not since after a few month of bringing it outside, the tins will have scratch all over the place and the paint coming out. That is the condition of my tin right now. It is not noticeable unless you examined it thoroughly. Having the flavor of Curiously Strong Mint is really a good choice because I always dragged curious attention to the cMoy and even more than my headphones or IEM that cost 10x more. So if you do get it, be prepared to be the center of attention among your friends or other people around you. Oh, if you are a frequent flyer, please do check with the laws of both the country you are in and the one you are going on the issue of whether if they allow such bare/ open electronics circuit to be taken on board. (The Airport Security might think of it as a bomb or a bomb triggering device. So do take cautious in this area)
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| OPA2227 and the Toggle Switch is for Bass Boost (Now Off) |
Sounds
The JDS Labs cMOy BB supports a wide variety of different headphone that carries different sound signature. So it gives a very good all rounder support for different headphones that you are having. I have once demo the low z configuration or the low impendence version of JDS Labs cMoyBB V2.03 and I find it to have a very good synergy with the Uniques Melody Mage and Unique Melody Miracle. Working on two great custom headphones is a complement to the JDS Labs cMoy because we rarely sees budget amplifier that can give a very good sounds to high end headphones/IEM. I’ve even heard that some people found good synergy with the HD800 which is very demanding and hard to please even when placed against high end headphones.
The cMoyBB works great with the majority of the songs that I’ve put it on but the moderate paced would make it unsuitable for certain faster songs unless your headphone is fast paced. Running on the JH16PRO with the Hifiman HM-602, the speeds is noticeably even slower because using hifiman as a source is a bit slow in its own and the darker tone of the JH16 makes it felt even slower. On the contrary, I find the pace to be sufficient for the majority of songs when running it with another normal paced DAC and iPod, and headphones besides JH16. So if you have a slow paced headphone and hoping of boosting the speed, then you will have better luck looking at somewhere else.
There is some good news though from JDS Labs for the cMoyBB. Their designs allowed the users to change the opamp to suits the taste of the users. So by finding a faster paced opamps, the users might be able to get a much better speed out of it. The original opamps which comes with the JDS Labs cMoysBB is the OPA2227 which has a moderate speed. As I said before, besides the JH16 and the Hifiman Combo, I did not find much problem in the speed.
The resolution and refinement is very good for this price range. It is not as highly as define as the higher end amplifier such as the SPL Auditor, but at this price range, I believe the refinement is something that is very hard to beat. There is also no grain in the sound for which certain amplifier at this price range will shows a lot of grain. So the clean sound allows you to hear more out of your music. The details is also quite good because you are not missing much around here and you can even get to hear the ambience and the soundstage of the things that is around you. Instruments are well separated with good amount of spacing and positioning. I won’t say it is the ideal ratio between the wideness and depth but again I’m still comparing it to something that cost approximately 16-17 times the priced of JDS Labs cMoy. But I still do hope to see a slightly wider and deeper soundstage (more spacious) from this amplifier. (OPA2228 sounded better because of the increased airiness in the soundstage) The soundstage performance is still above the average crowd, so you do not need to bother about it. (I’m also a sucker for big spacious sound so please judge the soundstage part yourself if it fits you) The only part where the JDS Labs cMoy wins over the higher priced SPL Auditor is on the musical side where the cMoy suits musical listening more than the more engineering sounding SPL Auditor.
The sound signature is on the warmer side with a mild mid centric sound that is quite unnoticeable at times. The mid centric sounds are not those that will congest the sounds like those found in Crossroads HR1. It still retains a lot of clarity to give you a clear sound with lots of details in it. The mids is not limiting the frequency extension on both ends. It does gives quite a nice balanced between the frequency ranged and not too overpowering against each other. (It’s not neutral or balanced sounding, just they didn’t overdone/ over boost the frequency ranges)
The linear frequency eq from the mids down to the bass section is very slow and good. In that sense the bass is quite warm and loveable. You will still get plenty amount of bass to satisfy most people even with Bass Boost off. The only complains in the bass section is the hope of having more low bass to complement it.
There is a bass boost switch inside the casing to allow you to boost the low ends by a small amount to give it an increased low ends and mid bass. The added bass can be good at times in which it solves the problem of requiring more low bass. At times the boost can be a bit unnatural in sounds and may not benefit certain songs. To certain bad tracks they may sound bloated in the bass while on those track that can give a good definition of bass, the added boost is quite good especially you are a jazz lovers that prefer more lower ends performance. The amount of boost still haves to depend on your headphone, some can hear more boost while those that are low on bass and concentrated on the highs (such as Hippo Shroom EB) might not be able to get much boost from it. My suggestion is to experiment on the Bass Boost feature and switch it on and off accordingly to find the flavor that suits you best. (Depending on your headphone and type of music being played) Besides music, running the bass boost does give you a better feel from the added texture in the low bass when watching movie. So watching movie with a bass boost on does give a better enjoyment out of it.
Changing to another opamp such as OPA2228, the sound changes very slightly and sometimes you can’t even guess which one you are using. They still retain much of the characteristics of OPA2227. The biggest changes are in the areas of mids where the OPA2228 is an alternative for OPA2227 for those who thinks the mids is too much on the stock OPAMP. The OPA2228 reduces the mids by a small margin and giving the impression of boosted energy from the top and bottom frequency. The added clarity also gives a slight impression of airiness in the mids. The changes are very mild and will not be as much as other opamp changes. Overall I still prefer the OPA2228 over the OPA2227. It is nothing much of who wins or loose, just a matter of sound preference.
Changing the opamp is an easy task. Using a pliers or other tools such as flat head screw driver could take it out but I do suggest getting a proper IC extraction tools so that you don’t bent the fragile legs/ pin on the opamp. If you do have a stock version of cMoy, I suggest you to get the simpler designs IC extraction tools than the 16 pin extraction tools that I’m having now. There are two large resistor blockings the extra length of the opamp removal tools thus making it quite hard to access the opamp and could pose the risk of bending the legs when not properly removed.
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| The Two Red Thing is blocking the access to the opamp for my IC Extraction Tools |
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| 16Pin IC Extraction Tools as You Can See Some Damage Already is Done on Both The Extraction Tools and the Legs of the Opamp |
This is a really good amplifier which I can say it is a benchmark for those amplifiers that falls within this range. Definitely the amplifier that is worth purchasing if you are after great sound quality with an all rounder sound while having the ability to power those headphone which you are having problem when you don’t have an amplifier such as those 150ohm and above headphones. Please do specify the headphone on checkouts so that John from JDS Labs can customize your amplifier accordingly.
Price: Without Rechargeable Circuit US$59.99
With Rechargeable Circuit US$64.99 (Please contact JDS Labs for more accurate pricing because this is based on the V2.03 version which doesn’t have the integrated charging unit into single PCB board on the latest V2.03R)
Source: Govibe DAC, Hifiman HM-602, iPod Classic
Amplifier: JDS Labs cMoyBB V2.03, Hippo Amplifier, Fiio E5, SPL Auditor
Headphones : JH16PRO, Beyerdynamic DT880 250ohm Premium Version, Superlux HD668B, Crossroads Woody 2 and various other headphone/IEM
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