[parked07]

Hey John thanks again and again for this amp. It's crazy to me how much of a difference it has made in my music. 
 
When I say that the bass boost is not worth using with the other amps I mean (and this may be completely different with another amp, maybe with more power) that its so wide of a boost, in that with the 2227 it is a tight boost with a good punch to it, this sounds like someone just turned up the low mids to a point where it sounds hollow, and without any definition. This was the same with both amps, but less so with the 823. I plan on getting a power adapter later so I'll see if that helps. The new amps do seem to need a bit more juice to get them going. 
 
Also the credit card did seem to help. The potentiometer (?) still seems a little fussy but I can live with that. I'm stoked with how this sounds. Thanks again man!
 

 

[jseaber]

Ah, that's the cutoff frequency of the bass boost. Swapping the stock 0.068uF Cb capacitors for 0.1uF parts will shift the curve down to your liking.

 

[UltimateCrash]

Hello all, I received a new cMoy 2.02 a few weeks ago as a gift from somebody and it's been working ok, except that I can't turn the volume knob up to the levels that I would like to before my headphones start cutting out ( The cutting out has gotten worse, I can barely turn the knob at all until it starts up again).  I'm using JVC HA-S700 headphones (32 Ohm impedance, one month old, and tested with other audio sources, so I think it's not the headphones) if that helps, but I myself do not know much about sound, so I don't know what the problem is really.  I went to your site Mr. Seaber and read that you can customize the amp to specific headphones, but is that what I need to get done?  Or are my headphones simply too weak? Or is my cMoy damaged somehow?  Thanks in advance to anyone who answers my questions, and pardon me if my question does not belong here.
 
- Crash
 

 

[jseaber]

Yes, customization is strongly recommended for 32 ohm headphones and below. Low impedance headphones demand more current. If you've been pushing the amplifier into distortion for weeks on end, you've likely damaged the TLE2426 by continuously pulling more current than it can safely supply. Along with gain adjustment, I can also install a second TLE2426 to double the current supply.
 
Note to all: Please contact us directly via e-mail or through JDSLabs.com if you need help.
 
Edit: Several have asked about this modification. The cMoyBB is normally assembled with a single Texas Instruments TLE2426 "rail splitter". These chips have been used in CMoys since 1998 for their superior performance over resistive voltage dividers. The majority of CMoy users need just a single TLE2426, but in rare cases (very low impedance headphones played at very high volumes), more current is demanded than any CMoy can supply. Turning on bass boost exacerbates the problem by roughly doubling the current draw. In such cases, the cMoyBB can be modified to accomodate dual TLE2426 chips. This leads to higher current handling and therefore higher clean playback volumes. So why not always use dual TLE2426 chips? Four reasons:
 
1) Most headphones above 32 ohms achieve very high volumes with less than 30mA (one TLE2426 is fine)
2) Battery life is nearly cut in half with 2 chips
3) Parts & assembly cost increase
4) The listener risks hearing damage at those higher volumes!
 
Therefore, it is optimal to use a single TLE2426.
 
Quote:

Hello all, I received a new cMoy 2.02 a few weeks ago as a gift from somebody and it's been working ok, except that I can't turn the volume knob up to the levels that I would like to before my headphones start cutting out ( The cutting out has gotten worse, I can barely turn the knob at all until it starts up again).  I'm using JVC HA-S700 headphones (32 Ohm impedance, one month old, and tested with other audio sources, so I think it's not the headphones) if that helps, but I myself do not know much about sound, so I don't know what the problem is really.  I went to your site Mr. Seaber and read that you can customize the amp to specific headphones, but is that what I need to get done?  Or are my headphones simply too weak? Or is my cMoy damaged somehow?  Thanks in advance to anyone who answers my questions, and pardon me if my question does not belong here.
 
- Crash
 

 

[UltimateCrash]

Thanks a lot Mr. Seaber, I'll go ahead and do that.

 

[gilency]

Just purchased the PCB. I will be using it only with IEM's with an impedance of 56 ohm (ES3X) and would like to be able to control the volume better than my Headsix (which I believe has 5 or 6 db at low gain).
Is 4X the lowest recommended gain?
Also, the volume knob from digi-key is hard to find  anywhere else since I am not willing to pay 8.00 just for shipping for a 6.00 item. Any other options?
Is the CUI 2.5mm Mono Jack needed? Mouser does not have an equivalent item.
Thanks

 

[jseaber]

@gilency: Lower gains are fine. Try a gain of 2 (R3 = R4 = 10.2k). The DC jack can be omitted (see Modifications). Any volume knob with a 0.25" shaft diameter can be used. RadioShack sells several (since you're in the US), or you can search the DIY forums here for more recommendations.

 

[gilency]

Thanks.

 

[gilency]

Which opamp would you recommend to increase the soundstage of IEM's like the ES3X?

 

[gilency]

Just received all the components. John, I had to pay 3.00 extra for the PCB package (had incomplete postage). The PCB looks very nice, like much much better than the Banzai 2.0.
Purchased 3 different opamps and will use a gain of 2 for my IEM's.
DigiKey and Mouser delivered. Just need a better hole puncher. 

 

[jseaber]

@gilency: No one has ever reported anything like that. Every single package from JDS Labs is manually weighed and processed by our local post office in Maryville, IL, USA (yes, despite their digitally prepared labels). Unless our post office made a mistake, there should never be additional postage due.
 
E-mail me a photo of the package/bill and I will be glad to reimburse you for the $3.00 charge anyway.
 
Quote:

Just received all the components. John, I had to pay 3.00 extra for the PCB package (had incomplete postage). The PCB looks very nice, like much much better than the Banzai 2.0.
Purchased 3 different opamps and will use a gain of 2 for my IEM's.
DigiKey and Mouser delivered. Just need a better hole puncher. 

 

[gilency]

I am very happy with your PCB.  Much better quality than the Banzai v2.
I should have kept the postage issue private. An issue not even worth mentioning regarding a very professional individual. My apologies.

 

[gilency]

I finished my cMoy BB tonight in a chocolate Altoids can. Looks and sounds pretty cool.
My second cMoy, and the best.  I have several opamps to try but is 3 am and have to go to bed. DIY is exciting!
I used a gain of 2 as suggested. Ideal for IEM's with better volume control.
There is something unusual I don't understand though:
a) with my iPod Classic, it sounds great either from the phone out or Lod.
b) with my 5th gen iPod Nano it sounds great from the phone out, but no sound comes out when using the Lod. Not sure if this particular Lod does not work with 5th gen Nanos or not. Any other explanations?

 

[komebudu]

Again, my CmoyBB burnt due to mishandling with the DC supply.
 
Sent to John for repair .... the job done was very fast...  without any additional cost requested... Thanks, John.
 
Then  I had the idea to go further to put some muscle to this unit... John suggested to DIY by adding additional dual TLE2426  http://www.jdslabs.com/diy_mods.php .
 
Equipped with AD823 chip, driving 12 Ohms NE-6 is such a breeze now...  no issue with clipping whatsoever...  Even with K701...  i can really push the volume LOUD ....  not only talking about quantity here...  the quality as well...  Awesome upgrade!!
 
My Fav setup at this moment:
 
NAD 502 CDP + DAE-1 (similar to MF X10D) + CmoyBB + NAD302 power amp section....  Sublime combination at very affordable price..!!!
 
Again..  always impressed iwth the CmoyBB ability and excellent customer service by John.
 
Cheers....

 

[jseaber]

Mishandling was by komebudu's young son, if I recall.

 
Quote:

Again, my CmoyBB burnt due to mishandling with the DC supply.
 
Sent to John for repair .... the job done was very fast...  without any additional cost requested... Thanks, John.
 
Then  I had the idea to go further to put some muscle to this unit... John suggested to DIY by adding additional dual TLE2426  http://www.jdslabs.com/diy_mods.php .
 
Equipped with AD823 chip, driving 12 Ohms NE-6 is such a breeze now...  no issue with clipping whatsoever...  Even with K701...  i can really push the volume LOUD ....  not only talking about quantity here...  the quality as well...  Awesome upgrade!!
 
My Fav setup at this moment:
 
NAD 502 CDP + DAE-1 (similar to MF X10D) + CmoyBB + NAD302 power amp section....  Sublime combination at very affordable price..!!!
 
Again..  always impressed iwth the CmoyBB ability and excellent customer service by John.
 
Cheers....