[jseaber]

The behavior you and "bolinao" have described is definitely abnormal. A cMoy with a gain of 6 (default for the cMoyBB) should be capable of producing clean playback up to 60-75% of its volume knob rotation when paired with 64 ohm headphones and an iPod at maximum volume. Lower impedance, higher sensitivity headphones generally reach maximum playback volume sooner. However, JDS Labs adjusts the cMoyBB's gain according to customers' headphones, so this example should remain true for most cMoyBB owners.

Regardless, a cMoy with a fresh battery should be quite capable of driving headphones to volume levels at least as loud as the portable audio player to which it is connected. Distortion should not occur from a source set above 25%.

I will be examining bolinao's amplifier as soon as possible. Each cMoyBB is hand assembled and hand tested. Therefore, there are no bad batches. This issue is most likely caused by a blown IC. As to how such a defect could arise, that is a mystery at this point.

Should anyone else encounter trouble, please do not hesitate to contact me.

--JDS
Quote:

I have had mine (2.02) for a few weeks, about 5-8 hours use as I went back to my old amp. My cans are ultrasone HFI-780 32ohms  . I dont know if the recent batch is faulty as i cant imagine this is standard. Ill check with my senn 555 which are 50ohms to see if its a sensitivity thing

 
EDIT (June 7, 2010):  I personally tested bolinao's amplifier and can confirm that it was an isolated faulty unit. Although his description suggested a weak battery, results were inconclusive due to moderate shipping damage. The amplifier passed oscillation/FFT tests at low volumes. However, it was received with obvious physical damage to capacitor C1, component U2 (TLE2426CLP), and the opamp. This type of damage can occur for any of the reasons stated in the Instructions guide (including shipping damage). A brand new cMoyBB would never make it past my workbench with such extensive flaws. bolinao's amplifier is shown below to provide documentation of a bulging/blown capacitor (also notice the spots of capacitor acid scattered across the board). Any device with a blown capacitor should be returned for repairs.
 
In conclusion: Be sure to follow the Instructions!
 

 

[Sinty]

i purchased a v2.2 on ebay today, cant wait to see how it works

 

[beaglepower]

I just got mine today. It shipped quick!
 
This is my first amp so I can't say how it compares to other, but I have my paired with my Senn HD555s and the sound quality has improved greatly. The BB is an awesome feature.
 
Ratatat has never sound better than now, in my case anyways.
 
Thanks for the great product!

 

[swbf2cheater]

I'd like to point out the 2.02 BB cmoy is perhaps the best portable amp I've ever used.  I actually prefer it to the D3 Python.  
 
It's got just the right amount of coloring and kick, the bass booster is pretty awesome.  I couldn't be happier.  Its one of the few buys I would recommend to anyone and that I am not at all dissatisfied with.  Amazing amp.  Got it in blue wintergreen
 

 

[sluker]

X2
I bought this amp in January and have since then expanded my collection with an icon mobile, a D3, a Tomahawk and an Sflo2 (includes a built-in amp). Even though all of these are more expensive and supposedly higher quality amps I still use my BB especially with the AKG 701's (the base boost compensates for the lack of base) and the HD280's for which it seems this amp was designed for.
My only gripe is that with todays air travel security I am hesitant to take this with me on the plane (I travel for work a fair bit) for fear of the plastic glove treatment

 

[TheGame21x]

Quote:

I'd like to point out the 2.02 BB cmoy is perhaps the best portable amp I've ever used.  I actually prefer it to the D3 Python.  
 
It's got just the right amount of coloring and kick, the bass booster is pretty awesome.  I couldn't be happier.  Its one of the few buys I would recommend to anyone and that I am not at all dissatisfied with.  Amazing amp.  Got it in blue wintergreen
 

Definitely agreed on all counts there. I love my CMoy BB.

 

 

[KnightK]

I built one myself by sourcing the parts and it was pretty fun to build. The final product was definitely worth it; I think it is the best bass boost under $100 that I have tried, ie bass seems pleasant and with minimal distortion. Plus, it just looks cool!

 

[komebudu]

Months ago I got problem with my CmoyBB...
 
Then had sent the unit back to John Seaber for repair (I'm pure mechanical guy after all), with $6.50 additional cost...shipping and parts.
 
The item had been repaired (Once received, John only took less 3 days to send it back to me..only the shipping time is sometimes very annoying, i would say) and i received it nearly a month later...  - Not your fault, John..
 
I had explained him how the amp was used. Fortunately my CX500 weren't affected by the fact that i accidently common ground my NW-A808 external supply to CmoyBB..see further below    - Not your fault, John..
 
Therefore, below are some observation and report by him:
 
------------------------------------------------------------------------------------------------------------------
Diagnosis:
Components U2, D2, and C1 damaged due to external electrical bridging of V- and Vgnd.
 
Cause:
Audio ground of the audio player shares ground with USB power supply ground. Charging of audio player via USD cable and common 22V adapter to headphone amplifier create an electrical connection between power supply ground and audio ground within CmoyBB.
 
Solution:
Disconnect CmoyBB power adapter before charging audio player from common USD charging cable.
 
Components repaired:
Replaced circuit board and ALL components. Amplifier optimized for AKG K701 headphones:
-Gain reduced from 6 to 4
-Rb changed from 24k to 16.2k
-C1 changed to Nichicon 470µF, KW series
-R2 and R4 changed to 1/8W parts
 
------------------------------------------------------------------------------------------------------------------------
 
 
Nice..and when i received my CmoyBB..  the best thing was he included in the bubble pack 2 pcs opamps.. LMXXXX  and ADXXXX... allowing me to evaluate personally the sound by swapping those opamps.I think it was my best $6.50 spent so far... on top of that... he even supplied me another 9V battery - Totally not your fault, John..
 
Now i love my CmoyBB better than ever. Paired with CX500 and newly received NE-6...make me happy again.... (NE-6 with OPA2227 is the way to go... IMO)
 
Can't try with K701 yet, since it had been sent for repair, due to distorted sound on left channel. Yes..  K701 needs power...but hey, it's no harm to get Cmoy amplifier to drive it...as long as I'm happy. Did I mention that I'm poor...?

 
I'm not promoting..  only to express my satisfaction how  sincere he is towards one of his customers.
 
Highly recommended product, and service...
 
Thank you John..!!! Maybe it's time for you to introduce us your another great product...

 
 
 
(sorry for my substandard writing skill)
 
 
 
 
 
 

 

[komebudu]

My friend gave me his Octave's DAE-1 on loan, which hw didn't use it for a while. I never know this product before.. . http://octave-electronics.com/Products/dae.shtml from NW-A808 > DAE-1>CmoyBB>NE-6... and WOW!.. CmoyBB seems to be more powerful..less prone to clip.. even i only run with 9V battery.... and even the NE-6's 12 Ohms.....
 
Can't wait to try it with K701...

 

[substance90]

Guys, would you recommend the cMoy v2.02 for AKG K271 MKII for usage with the headphone output of a notebook or do I need a DAC for this purpose? I`m just not happy enough with the bass of my cans.

 

[komebudu]

 
Quote:

My friend gave me his Octave's DAE-1 on loan, which hw didn't use it for a while. I never know this product before.. . http://octave-electronics.com/Products/dae.shtml from NW-A808 > DAE-1>CmoyBB>NE-6... and WOW!.. CmoyBB seems to be more powerful..less prone to clip.. even i only run with 9V battery.... and even the NE-6's 12 Ohms.....
 
Can't wait to try it with K701...

Got my K701 finally....
 
The drive units had been changed to new pairs.. Technically..  it's brand new K701.
 
The problem is that..i have to run the burn-in process again..   Alas !!  
 
"Out of the box", combined with Toshiba DVD player, DAE-1 and modified CmoyBB 2.02..  K701 Wows! (i hope more WOW! prior to burn-in process)...  sweet and pleasant sounding. ..  very nice indeed, compared to previously, a slight trace of sibilance though. And now i can use Bass Boost at the CmoyBB.   This CmoyBB seems less tendency to clip after being optimized, as mentionned before. For normal or confortable listening level, i don't have any issue... because mainly i listen to classical, jazz and acoustic concert. My fav CD right now is Lara Fabian - En Toute Intimité... ahhh.... superb performance...great recording.
 
Now I'm a happy man...  (until my head-fi desease re-occur, one day)

 

 

[pekingduck]

Ordered one today... Can't wait to compare it to the PA2V2

 

[parked07]

First off I apologize for bumping a somewhat old thread. I believe this is my first post on this board. I've been lurking for quite a while and decided to write in about my experience with this amp. I have decided to replace the stock OPA2227 with a AD823ANZ and have tried a AD712JNZ. I haven't read anything about amp rolling with this amp in particular so I'd like to share what I found if you guys don't mind
 
I use a pair of ATH-M50s with this amp. These sound great unamped but I was looking for something to help increase the sound stage and maybe give me a bit more kick and volume then what my Macbook and iPod can give me. 
 
Out of the box this is a great amp. I've had it for about a year now and it has been great. It definitely grabs attention for it's design (but I would imagine the same is true for any CMoy) and the build quality is superb. Little things like the auto power off when the battery's unplugged, or the foam to help hold in the battery shows their attention to detail and knowledge of what matters to the customer. It's more than capable of driving my headphones and the OPA2227 sounds great. Very detailed (after burn in) and but it seemed to do nothing for my main problem with my M50s, which is the limited soundstage. They did have a somewhat neutral sound to them but I feel like the highs were kind of accentuated, and the low end was kind of lacking. After looking around on this forum I read some reviews of other amps and looked a lot into amp rolling. I had no prior experience with this kind of thing and so I emailed JDSLabs and like when I bought it, he got back to me within three hours. He gave me a lot of good reference links and recommended a few amps. Customer Service is amazing with this guy. It's unlike anything I've experienced from any other company. I'd buy fifty more amps just because of that. 
 
I took advantage of the sample program with AD (which I feel kinda bad about) and got the amps very soon after. Rolling was a piece of cake because of the socketed amp and detailed instructions can be found on the JDSLabs website. 
 
I'd like to talk about the 712 first. It is extremely crazy to me how revealing it is. I can hear members of the orchestra from The Parent Trap Suite (I'm completely aware at what a lame choice of music this is, but I have a thing for soundtracks and this suite always gets me nostalgic) breathing or flipping pages. Piano benches creak in Diana Krall's "Live In Paris" and I can hear the plucking stand out on both the guitar and the bass as well as audience members coughing, etc... The mids are just there and they seem right. The low end is AWESOME. But let me say that on both of the amps I tried, the bass boost is useless. Which I understand as I assume they have been tuned to the OPA2227. Regardless I don't even care as the sound from this amp was great. The highs were just so perfectly tuned it seemed like they had been made for my headphones. But alas, my soundstage problem had only been mildly helped, and at times the amp seemed unable to power the amp, as distortion occurred where I know the headphones could reach. On a side note I have tested these headphones using both a Samson Servo120 and a very old Sony MDR 4 track minidisc recorder and an EQ to see just what (or rather where) these headphones can reach. I know that I can buy a power adapter or wire in another battery but I'm only 17, my source of income is non existent and those adapters are wicked expensive. 
 
Anyway I decided to switch to the AD823 and to prevent redundancy, I'll just say all of the revealingness of the 712 was there but with such a better texture (its smooth and responsive and able to keep up better with fast music. I'm not good at using descriptive adjectives and for that I apologize. Also it fixed my tight claustrophobic music with (YAY) an incredible soundstage. Everything has a place now. I listen to a lot of Owl City, Rocket to the Moon, Hawk Nelson and Diana Krall as well as some recordings I've done myself and one of my favorite pianists, Emile Pandolfi. Everything sounds stereo ya know? All the instruments have places and I can feel like I'm in the middle of the band. 
 
I'm really sorry about the quality of this. I'm not nearly as good at reviewing as the other members on here. But I would like to say if you have this amp, try rolling the amp. It's an amazing difference. The amp out of the box is amazing, you won't regret it. But if you can find a way to get these amps, do it. It's awesome. Especially if you can get a power adapter because even the 823 seems thirsty once in a while. Also be aware the bass boost is not worth turning on anymore, which I'm more than fine with as they really helped bring out the bass in my M50s. 
 
If your still reading and want to know more I'd be more than happy to post more. I just don't know what to post about Thanks for reading though.
 
P.S. If your reading this still Mr. John ever since I rolled this bad boy I seem to be having a problem with the VGround. I hear humming when I touch the input or the volume pot. Also the pot seems wicked dirty now. When I turn the knob it kinda crackles. Any suggestions? 

 

[komebudu]

Hmm..  interesting.  
 
John had also recommended me to try AD823 chip for K701...  which i didn't yet.  Perhaps should give a try.....
 
thx P07

 

[jseaber]

Great info! Could you elaborate on what you mean by, "bass boost is not worth turning on anymore" with the other opamps? This is surely not true for everyone. The OPA2227 goes well with the default bass boost configuration, but it is purposefully tuned for a warm, powerful sound that can be overwhelming with certain opamp/headphone combinations. Some slight adjustments would restore the feature's impressiveness with your equipment.
 
Regarding the humming after opamp rolling, have you tried reverting to the OPA2227? I have never known humming to be a problem. I can only suspect that a short has occurred, or the potentiometer has physically worn out. Slide a business card (or something equivalent) beneath the circuit board; this will ensure the board is isolated from the tin. If that doesn't help, send me an e-mail and we can get your potentiometer replaced.
 
--JDS
 
Quote:

First off I apologize for bumping a somewhat old thread. I believe this is my first post on this board. I've been lurking for quite a while and decided to write in about my experience with this amp. I have decided to replace the stock OPA2227 with a AD823ANZ and have tried a AD712JNZ. I haven't read anything about amp rolling with this amp in particular so I'd like to share what I found if you guys don't mind
 
I use a pair of ATH-M50s with this amp. These sound great unamped but I was looking for something to help increase the sound stage and maybe give me a bit more kick and volume then what my Macbook and iPod can give me. 
 
Out of the box this is a great amp. I've had it for about a year now and it has been great. It definitely grabs attention for it's design (but I would imagine the same is true for any CMoy) and the build quality is superb. Little things like the auto power off when the battery's unplugged, or the foam to help hold in the battery shows their attention to detail and knowledge of what matters to the customer. It's more than capable of driving my headphones and the OPA2227 sounds great. Very detailed (after burn in) and but it seemed to do nothing for my main problem with my M50s, which is the limited soundstage. They did have a somewhat neutral sound to them but I feel like the highs were kind of accentuated, and the low end was kind of lacking. After looking around on this forum I read some reviews of other amps and looked a lot into amp rolling. I had no prior experience with this kind of thing and so I emailed JDSLabs and like when I bought it, he got back to me within three hours. He gave me a lot of good reference links and recommended a few amps. Customer Service is amazing with this guy. It's unlike anything I've experienced from any other company. I'd buy fifty more amps just because of that. 
 
I took advantage of the sample program with AD (which I feel kinda bad about) and got the amps very soon after. Rolling was a piece of cake because of the socketed amp and detailed instructions can be found on the JDSLabs website. 
 
I'd like to talk about the 712 first. It is extremely crazy to me how revealing it is. I can hear members of the orchestra from The Parent Trap Suite (I'm completely aware at what a lame choice of music this is, but I have a thing for soundtracks and this suite always gets me nostalgic) breathing or flipping pages. Piano benches creak in Diana Krall's "Live In Paris" and I can hear the plucking stand out on both the guitar and the bass as well as audience members coughing, etc... The mids are just there and they seem right. The low end is AWESOME. But let me say that on both of the amps I tried, the bass boost is useless. Which I understand as I assume they have been tuned to the OPA2227. Regardless I don't even care as the sound from this amp was great. The highs were just so perfectly tuned it seemed like they had been made for my headphones. But alas, my soundstage problem had only been mildly helped, and at times the amp seemed unable to power the amp, as distortion occurred where I know the headphones could reach. On a side note I have tested these headphones using both a Samson Servo120 and a very old Sony MDR 4 track minidisc recorder and an EQ to see just what (or rather where) these headphones can reach. I know that I can buy a power adapter or wire in another battery but I'm only 17, my source of income is non existent and those adapters are wicked expensive. 
 
Anyway I decided to switch to the AD823 and to prevent redundancy, I'll just say all of the revealingness of the 712 was there but with such a better texture (its smooth and responsive and able to keep up better with fast music. I'm not good at using descriptive adjectives and for that I apologize. Also it fixed my tight claustrophobic music with (YAY) an incredible soundstage. Everything has a place now. I listen to a lot of Owl City, Rocket to the Moon, Hawk Nelson and Diana Krall as well as some recordings I've done myself and one of my favorite pianists, Emile Pandolfi. Everything sounds stereo ya know? All the instruments have places and I can feel like I'm in the middle of the band. 
 
I'm really sorry about the quality of this. I'm not nearly as good at reviewing as the other members on here. But I would like to say if you have this amp, try rolling the amp. It's an amazing difference. The amp out of the box is amazing, you won't regret it. But if you can find a way to get these amps, do it. It's awesome. Especially if you can get a power adapter because even the 823 seems thirsty once in a while. Also be aware the bass boost is not worth turning on anymore, which I'm more than fine with as they really helped bring out the bass in my M50s. 
 
If your still reading and want to know more I'd be more than happy to post more. I just don't know what to post about Thanks for reading though.
 
P.S. If your reading this still Mr. John ever since I rolled this bad boy I seem to be having a problem with the VGround. I hear humming when I touch the input or the volume pot. Also the pot seems wicked dirty now. When I turn the knob it kinda crackles. Any suggestions?