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Review: cMoy Headphone Amp Bass BOOST Edition - Page 13

post #181 of 192

Yeah... John...  your memory is intact...smily_headphones1.gif

post #182 of 192

Hello mr Saber


I am thinking of buying one of the 2.2 version i saw in your ebay page to drive my re-252 and re-262 through a clip+


i wanted to ask if there is any modifications need to be done to your amp or it works fine as it comes ?


I am a complete noob with amps but this looks like a good one for starters


My only concern is , will it require anychanges or these 2 IEM's are fine for use with the 2.2. version ?


Thank you


(if anyone else can help me out , please chime in your 2 cents)

post #183 of 192

How much would a customized unit be with 2 chips?  I will be using Audio technica es7 32 ohm headphones

post #184 of 192

  Mr. Seaber repaired my Mccoy very quickly and shipped it back to me very fast as well.  My headphones sound great with this awesome amp!  I am very pleased.



post #185 of 192
Originally Posted by ADD View Post

I always wonder where all the actual mints go with these things.

Some ones  getting pretty hefty ha ha !


post #186 of 192

Any plans for making it rechargeable? How about selling on Amazon?

Edited by UnityIsPower - 12/9/11 at 3:57pm
post #187 of 192

I would like to apologise to John Seaber, famed cMoy maker, Electrical Engineer, Chief Executive Officer and President of JDS Labs, Inc. (based in Illinois, Maryville, US), and a DIY enthusiast.

I am going to make no excuses, but here is the simple point; I let John down, twice, by not writing reviews for two amps I bought of him between 2008 and 2009 (cMoyBB v2.00 and a Custom cMoyBB v2.02). Rather than write a brand new review for either (since both are technically discontinued), I would like to write a report on how awesome John is, some of the messages and emails we sent to each other in purchasing/building cMoyBB amps, and my mini-review of the Custom cMoyBB v2.02 that I wrote to him but never published anywhere. There is a reason why I am resurrecting this thread, but that reason will become clear at the end, or you can just check out this topic.


So, lend me your ears (eyes) for a moment (as a disclaimer, this is a potential TL;DR post; if you have the strength to read it, then you are seriously awesome, but not as AWESOME as John :p):


The first time I contacted him was in March 2008 when I was searching for an amplifier for my newly acquired Ultimate Ears Super.Fi 5 Pro’s and my Etymotic Research ER-6i’s; both items are now discontinued (and Jerry Harvey no longer works at UE and UE is owned by Logitech). At the time, he was still studying a degree in BSEE at Missouri S&T, and he operated a shop using eBay as a frontend.

After working through the Head-Fi.org forum, I had selected a few amps that I was considering to buy, but to keep things short, I went and opted for the cMoyBB v2.00 headphone amplifier from John. We exchanged messages between us using mainly the eBay messaging service, but some of this has been lost, and some are unnecessary for this thread

I promised to write a review of the amp on this forum (the one I am in right now), and I never, never did.


Fast forward just over a year later, to 6th July 2009. I re-contacted John again at the end of that Summer to inquire about his latest amp, the cMoyBB v2.02, but also to talk about my previous amp and, at the time, my new job.

First, my old cMoy v2.00. It was malfunctioning. Badly. For just under a year. Here is a quote, from me to John, when I wrote him an email describing the problem:


“The problem is that: the input 3.5mm jack is not performing as it should, cuts out the left channel, introduces noise, lowers overall volume, does not provide a secure fit (an inserted TRS/3.5mm connector sometimes pops out during use)…


“I have looked at the differences of the socket on the PCB with my naked eye, and can see that whereas the output socket looks like it is double the size of the input socket. I assume that this was done for space. I also shone a light done the two sockets, and can clearly see that the internal parts of the connectors look different; the output socket has what looks like two prongs touching, whereas the input prongs hardly make contact. I presume that when I connect my cable in, the input connector prongs do not make a complete connection to the TRS jack, thus causing issues with sound.”


I also wrote:


“Rather than having this fixed, I would like a new amp, but for one very important change (beyond my suggestions for a possible custom built amp); I would like both I/O sockets to be of either higher quality, or that the sockets are more durable from stress (such as in my jean pockets or otherwise). At least so that this problem does not arise again.
I can also salvage the old amp, and do some opamp rolling ;)”


So, what about his latest (then) amp? I wanted a custom built amp, not the standard one he offered to customers. I went and wrote what I wanted in detail, and told him that I was pushed for time; my new job would start very soon (August), but I did not want to rush him. Of all the customisations I wanted, I especially wanted no more issues with cable connections (TRS contact issues) at all. (For the purposes of this post, I won't write what those inital customisations were, as it is irrelavnt).

He replied back, told me what was not possible, but offered many alternatives to really make a great amp. After some more exchanges, we agreed on what the build should be and the total cost via email. I paid him (via PayPal) and, seriously the best part, he actually built it quickly for me. To be clear, I spoke to him on the 6th July ’09, paid him on the 9th, and received a fully built Custom cMoy BB v2.02 on the 16th. A further note, I live in the UK. Yeah, seriously, I bet there are few people who could do this, and he really is awesome (will continue to say this, bear with it :D).


This following is a list of what made my cMoyBB v2.02 a ‘custom build’ over the, at the time, standard (he actually wrote this on my paper order form when I received my jiffy-bag envelope parcel, so I will transcribe it word-for-word):


  • Hand Selected Alps RK097 potentiometer
  • 330Ω DC coupling
  • Gain = 4
  • Premium nichion 470µF KW capacitor
  • New Kyron STX-3100-9C output jack.


(He underlined the ‘9C’ part of the ‘STX-3100-9C’ output jack for emphasis on my order form).

Just to expand, the Gain is set at 3.3kΩ, and the Alps RK097 is a 10k potentiometer.

The amp would also uses the Burr-Brown OPA2227PA op-amp, which is such a beautiful OPAMP, *swoons*!

On that note, one or two of these modifications are mentioned on the JDSLabs.com DIY section, which talks about building your own cMoyBB v2.02 amp; take a look :)

To make the whole affair sweater, in the original discussions he said not to use a particular OPAMP, the LM4562NA, as it causes interference with wireless access points, but he included it, for free, in case I ever wanted to use it. Unfortunately, I have never used it; it is still in the original anti static bag inside my (still kept) jiffy-bag envelope he used to send me my custom amp.

Before I go any further, his last email to me (20th July 2009), he asked me to say in my future review (I never wrote a review for either my amps...) that the Kyron STX-3100-9C will be a standard part until mid-August 2009; obviously too late now, but at least it is mentioned.


When I received the new amp, I immediately compared it with my old one; to get the old one to work, I had to physically push the TRS connector of my interconnect cable to one side to make contact, but other than that, I was able to make some healthy observations. Rather than write this out again after two and a half years, I will post my mini-review that I sent him, now visible and open to the public. As another disclaimer, I was much younger then, so please ignore the biased, sometimes childish, and poor writing/reviewing skills:



Sent to John Seaber on Sunday, 19 July 2009 @ 08:09. (Click to show)


Sent to John Seaber on Sunday, 19 July 2009 @ 08:09.




"Hi John,

I have finally received your amplifier on the 16th!
Just looking at the internal restructuring of your Custom cMoyBB v2.02 circuit board against my old v2.00, and I am quite impressed at your handiwork! It seems that you have continually tried to improve on your older designs rather than re-hashing old ideas; something that I commend you for.

I also had a look and identified the custom internal components; the 330Ω DC coupling value resistors and the Nichion 470uF "KW" capacitor are the most obvious changes, and both look well soldered (I actually like the look of them on this new circuit board rather than the v2.00 respective components). I am very, very pleased with the Alps RK097 10k potentiometer; the pot is simply incredible over the old amp's pot. I love the movement of the pot; it is just so much more responsive than the v2.00. I like the smooth, but resistive/solid turn of the pot, which feels very reliable, far exceeding the older amp. More importantly, the volume is better controlled with this amp, very accurate over the v2.00. I also like that the volume knob of the potentiometer is not too close to the lid of the amp, which makes turning the pot more comfortable, and looks better (does not have an 'angled' look like my v2.00).
There are major design improvements I find with this custom v2.02 amp over the old v2.00 amp. The potentiometer and input/output jack’s re-placement make it easier to use cables and I have a more accessible pot (rather than thumbing between my cables trying to use the v2.00 pot). The internal bass boost switch is a smart idea, giving the amp a more discrete look, and better allows for better fit in my pockets. Although a bass boost potentiometer would have been nice, in reality, the internal switch is a far more convenient option and is less susceptible to environmental changes, such as the rubbing of my amp/iPod in my pockets (unlike the v2.00). The threaded Kyron STX-3100-9C jacks look superb against the older jacks from the v2.00, and give a more, secure fit when I use my 3.5mm connectors. Indeed, your cut holes are far better than the v2.00!
This custom cMoyBB v2.02 amp simply looks more professional than the old v2.00 amp.

So, after enjoying the look and build of your amp, what do I think of the sonic quality? Absolutely stunning!
As a stress test, I performed an A/B test between your custom cMoyBB v2.02 and the cMoyBB v2.00 amplifiers, using my iPod Classic 160GB as the source. This was connected to my NuForce Icon amplifier (with the stock 23W PSU), and I played lossless music to first my JohnBlue AudioArt JB3 loudspeakers.
It was obvious that the two amps had very different SQ. I could play my music at a higher volume on the custom cMoyBB v2.02 than the old cMoyBB v2.00. Also, the bass is far more controlled with the new custom v2.02 amp when I switch on the bass boost switch. I can actually go louder overall with the BB switch on without bass distortion, something the old amp cannot achieve. The increased volume is not what I intended as being important, just the fact that the custom v2.02 is more powerful and more refined in dynamics and soundstage than the old v2.00 amp, and can achieve this at both lower and higher volumes. Overall, very impressive!
Now, onto a harsher test; the same setup, but using my 'AKG K 701' circumaural headphones instead of my loudspeakers.
These headphones are super accurate, very precise, and have amazing imaging coupled with breathtaking soundstage. So how did the custom v2.02 fare in this test? Fairly well, I would say, but it brought down the overall finesse of the K 701, simply because this cMoy amp cannot give enough [head] room for the headphones to breathe; the K 701 are extremely hard to drive, so even when I used the v2.02 as a preamp before the signal is passed to my main amp, the headphones suffered from detail and soundstage. Indeed, they felt like I was using in-ear monitors (IEM), albeit an awesome beast compared to my two IEM's. I tested before and after the BB switch and it helped bring out the best bass of the K 701, but at a loss of fine detail in the other frequencies. Nevertheless, I still enjoyed this setup, and I am impressed that custom cMoyBB v2.02 performed so well.
I tried using just the iPod, cMoy v2.02 and my K 701, but this was not a good combination. The bass boost needed to be on for the K 701 to actually present the music well in the lower frequencies, but there was not enough power from both the v2.02 and the iPod to really allow the K 701's to work at their best in all the frequencies and both soundstage/imaging suffered. I believe the iPod is the first, main cause of this issue. Yet, again I am surprised at how the custom cMoyBB v2.02 can perform so well on the AKG K 701, there are not many amps, let alone portable amps, that can at least drive and play music on these headphones, and play at least somewhat well (I still enjoyed listening to this setup, just that it does not beat my soundcard and amp).

Finally, I have used your amp for its intended purpose, portable headphone amp. I have used both my Etymotic Research ER-6i isolator and Ultimate Ears Super.Fi 5 Pro IEM's with the custom cMoyBB v2.02 and my iPod; absolutely superb!
Playing music like this is fantastic, the ER-6i's gains new life when I use your amp, and are stunning with the BB switched on. The Super.Fi 5 Pro's are extremely soulful and have a 'live' like sound to them with the v2.02, and the BB switched on gives me the impression that I am at a live gig! I enjoy (and missed) using your amps and this new amp simply blows my old v2.00 away into the nether regions. The soundstage and imaging from your amp is amazing and very enjoyable.

My custom cMoyBB v2.02 amp is clearly ahead of my old v2.00 in SQ, it is far clearer and causes less clipping on my audio gear when I increase the volume; the amount of headroom from your amp is stunning.

I will publish this mini-review, with much refinement, in the future on Head-Fi.org, as I am away with a new job. I shall road test the custom cMoy BB v2.02 and report on changes of the amp and my listening experiances later.

Thank you John for making this amp, I am extremely pleased, and I cannot wait to see how you progress in the world of cMoyBB!

Kind regards

[Contact Information and name redacted]



(P.S I apologise for some of this email if there is any illegibility and/or repetition)

(P.P.S. feels good to update my audio signature :p )



Desktop Audio Rig:

  • PC (Vista SP2 with ASIO4All drivers) playing MP3 [Lame], High Resolution WAV or AIFF, FLAC or ALAC/Apple Lossless via Foobar2K/Songbird/iTunes respectively;
  • Asus Xonar D2X PCI-E soundcard;
  • Zu Audio Zu Cable Pivot™ (Mk2) Miniphone > RCA Cable (1.0 m) [stereo miniphone connector (3.5 mm) > RCA / RCA with 8" leadout]
  • NuForce Icon Desktop Amplifier/DAC/Pre-Amp/Headphone Amp;
  • JohnBlue AudioArt JB3 loudspeakers or AKG Acoustics K 701 circumaural headphones.


Portable Audio Rig:

  • Apple iPod 6G 160GB;
  • Audio Line Out (ALOaudio.com) iPod Female Connector;
  • ALOaudio.com JenaLabs Jena Wire Jumbo Cryo 3.5mm Mini to Mini (4 inch cable, 6 inch tip to tip) cable;
  • JDS Labs (John Seaber, www.jseaber.com) custom cMoy v2.02 Bass Boost (via internal switch) headphone amplifier with Texas Instruments Burr-Brown OPA2227PA op-amp. This amp is custom built with the following changes: gain selection at 4 (3.3kΩ), Nichion 470uF "KW" electrolytic capacitors, 330Ω DC coupling value resistors instead of Vishay/BC 1uF Metallised Polyester Film Capacitor or WIMA 1.0uF Polyester Film Capacitors, Kyron STX-3100-9C (threaded) input/output jacks, and a hand selected Alps RK097 10k potentiometer;
  • Ultimate Ears Super.Fi 5 Pro canalphones;
  • Etymotic Research Inc. ER-6i isolator canalphones."






He wrote back, in his last email to me, the following reply:



Received from John Seaber on Monday, 20 July 2009 @ 04:10 (Click to show)


Received from John Seaber on Monday, 20 July 2009 @ 04:10






Thanks for your thorough and praiseful remarks! If I had the time, I’d give a more thorough response. Again, I truly appreciate your feedback. Customer responses such as yours are the reason I continue running JDS Labs.


One thing: If you mention the STX-3100-9C in your “future” Head-Fi review, please remember to note that this will be the standard part by mid-August 2009.


Best regards,


John Seaber








Since that time, near the end of 2009, I lost one of the Super.Fi 5 Pro earpieces, which left me devastated, but also my entire lossy collection of music (13,000+ tracks) became corrupt on my PC, leaving my 6th Gen iPod Classic 160GB (2007 edition) the only place where they now exist; it also had some 3,000 lossless FLAC files, but not my entire collection. My FLAC/Apple Lossless stuff on my PC was fine, but I have (still) never updated my iPod since. My lossless collection has since grown, and I use Spotify Premium for lossy music playback, but I hardly ever use my portable rig except long car journeys.

In some ways, my initial rigs, as outlined in the first email written above, has not changed much, save for using foobar2k almost exclusively for all music using WASAPI mode and other tidbits.


Now that you may or may not have read that report, here is why I am posting this after a long time.

I am in the market for a new amp, simply because I just bought an Ultimate Ears Triple.Fi 10 Pro IEM from Amazon.co.uk Boxing Day Deals (still going) for £109.99, which I have mentioned in various, many topics, including my own.

Unfortunately, when I received my IEM’s early in the morning of the 31st Dec 2011, I had received a defective, D.O.A IEM. I have described it here (and again in a follow-up post) and here if you are interested, but please read the rest of both topics; I am receiving a new replacement this week or next Monday (6th - 9th Jan 2012) from Amazon, so all is good; their customer service is brilliant.


At the moment, I don’t have a huge amount to spend, so my budget is small, but I decided to do one of three things, either: get a professional portable amp, continue to enjoy my still working Custom cMoyBB v2.02 amp, or invest in a customised Rechargeable, 2x9 batteries cMoyBB v2.03.

I have decided to go for the former option, but pre-order and buy the c421 Headphone Amplifier from John (get the amp now with 2nd batch faceplates, and get the new, 3rd batch faceplates in February). After much research, he still comes up top for amazing quality amps at very budget prices.

This gives me room to possibly order a set of custom mould ear sleeves (tips) for my Triple.Fi 10’s later this month, since I have been entertaining this idea for a while now. ACS Communications Solutions (alternate site) are pretty famous in the UK for making ear moulds for Etymotic, but they do make ear moulds for other earphones (ACS UK Custom Fit Earphone Sleeves). I have three places where I can get this (HiFiHeadphones.co.uk, iHeadphones.co.uk, or BootsHearingCare.com), so there is no rush and I can mull over which would give me the best to purchase from.

I can also invest in a nice new line-out-dock (LOD). Indeed, I  am thinking getting Moon-Audio.com’s Silver Dragon V1 LOD Cable  or Silver Dragon V3 LOD Cable, but this depends on what cash I have remaining.

Finally, I am interested in purchasing the FiiO RC-UE1 Replacement Cable for Ultimate Ears IEM’s from HiFiHeadphones.co.uk, but this is more of an afterthought. Plus, there is no memory wire in these cables, which I like, and due to the weight and the little fact that I wear spectacles, I will need to do further thinking and research before I shell out money for it.


I will be making this order very soon, but first, I need to send some…emails...to John Seaber; I will make an apology to him for not writing any reviews all those years ago, and then ask him some (lots of) questions about the C421.


I will update the following thread, and create a separate one to review the C421 Amplifier (depending on the conversation between John and myself via email), and thank you to anyone who read the entire post. I think you may be crazy, but I guess if your already a Head-Fi member... :)

Edited by TheOneInYellow - 1/3/12 at 1:08pm
post #188 of 192
Hope you guys don't mind me bumping the thread. I was debating between keeping my fiiO 5 or getting the FiiO 6 or 11 after research I decided to order a Cmoy with the AD823 and bass boost from hpa_labs at $45 hopefully I didn't make a mistake. I'm not a Audiophile by any means just a good music fan boy.
post #189 of 192

The JDS cmoy I use generally provides more raw power then my portable player for my HD25s, depends on the headphones you will be using them with.

post #190 of 192

I ordered a V2.03 rechargeable CmoyBB today from JDSLabs through John, really great service, he was prompt to reply to my emails when I wanted to make an order correction as it's going to be customized for my triple-fi 10 and other IEM's 32 ohms and under. Cant wait to try it after all the rave reviews I've been reading! This amp sounds perfect for my applications and portable needs!  Price seems really resanable too. Shipping to Australia was next to nothing compared to other purchases I've made.

I'll report back when it arrives! 

Edited by H20Fidelity - 6/5/12 at 10:02pm
post #191 of 192
Is the sound neutral or does it add flavor? Is there any noise like hiss? I saw one that uses TWO 9v batteries for an "audiophile" grade Cmoy. Is that hot air?
post #192 of 192
Thread Starter 

Those wondering if I am still around, yes I am and till today it is still one of my most favourite cMoy amps.

However I did order a new unit, after my first great one that I gave to my uncle.

The only thing I was not too happy about was that John only gave me a tiny tiny discount. 

Otherwise? Same old, solid product. Be sure to keep your 9V's fresh otherwise the bass tends to distort once your low on battery.

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