[bootdsc]

  Does the higher V circuitry and opamp benefit the higher impedance cans?
I have a pair of 600 ohm 990s
 

Sure does, use this calculator. Put in the ohm rating and play with the voltage to get an idea of the max amperage physically possible at any given voltage, oh and remember each rail can only sink half the voltage so cut your V source in half(best case scenario if using rail to rail op amp) . Now that you know the max amp's you can pull check the sensitivity of your headphones to figure out how much amperage you need in order to driver them loud enough for your liking. Please forgive any errors in my statements as i'm not a expert but just a hobby enthusiast.

 

[bootdsc]

  Last question is how much voltage can the rest of the cMoy circuitry handle if I switch the opamp and use a step-up?

Missed this one, to be safe you should use capacitors rated double that of the power supply voltage but for a cmoy you can get right up to the cap voltage long as you don't go over. For instance i use 10v caps because of the much smaller physical size and run my cmoy's at 9.05v. But don't listen to me, its not the proper use of caps.

 

[Bassman999]

I have never heard of LIPO chargers, but I am looking that up as soon as I type this.

 

[Bassman999]

  Missed this one, to be safe you should use capacitors rated double that of the power supply voltage but for a cmoy you can get right up to the cap voltage long as you don't go over. For instance i use 10v caps because of the much smaller physical size and run my cmoy's at 9.05v. But don't listen to me, its not the proper use of caps.

Ok so the weak link in my cMoy and its ability to have a higher rail voltage will be the caps...
Ill look in there and see what its comprised of, and if I can mod this thing.
I cant do a from scratch one I dont think based on my poor vision.

 

[Bassman999]

  Well i only use batteries with cmoy's because the power supply will add a lot of noise unless its filtered but then you are getting way to complicated for a simple cheap cmoy type amp. Maybe i left out a key detail, i use a 3.7v lipo with the step up converter and a li po charger with all of the portable amps i have built. Depending how much space i have and if the battery can be easily removed ill ether use a usb lipo charger or external charger. I could never understand why people are willing to pay for disposable batteries especially 9v's having such a low ma rating. 

do you use a high capacity 3.7v LIPO batter like 1200 or 4400 mAH or small like 500mAH
 
I saw this charger..

Simple and cheap

 

[bootdsc]

I have them in a bunch of capacity's, it really just depends how much space i have but this probably gets the most usage 
http://www.amazon.com/Trust-TrustFire-Protected-Rechargeable-Batteriesed/dp/B005X4SG7W/ref=pd_sim_e_5?ie=UTF8&refRID=1CR3B248EEDDF53NX25A
 
For longer battery life ill use the 2400ma version but it's kind of bulky and doesn't fit most cases
http://www.amazon.com/TrustFire-Protected-2400mAh-Rechargeable-Batteries/dp/B00ABE7WB0/ref=pd_sim_e_5?ie=UTF8&refRID=1AZG23FCFBZCGWZ4ZC0J
 
Amazon is not the cheapest place to buy them but its the quickest place to find. Make sure what ever you get has protection circuit built in. 
 
There is one problem with using lipo's like this, the dc dc converter will keep running and drain the battery well past its safe limits and i have killed one or two batteries this way. You can tell when the battery is getting low because the step up converter starts acting weird and you will hear the distortion. My advise is to just remember to recharge long before the battery fully drains. with 900ma and the 80% efficient dc converter and depending if you run the cmoybb v2 in class A i get about 15 to 30 hours of play time so other then leaving it on over night it feels like i never have to recharge them. BTW the 900ma battery (with protection circuit that adds a few mm length) will fit in a AA battery holder.
 
Oh and the power switch needs to go between the batt+ and anything else. Depending on the charger board they sometimes slowly drain the battery if its left plugged in so its a good place for the switch.

 

[Bassman999]

I grabbed the 900mAH with protection and a charger.
I am going to go with the adjustable step up that goes to 25v, since the caps are all 40v and 50v rated

 

[bootdsc]

That might not work, there is a limit to how high a voltage you can get based on the input voltage and the type of IC used on the board. it might not go all the way to 24v with only 3.7v input but you'll get at least a high enough voltage to be useful.
 
The max voltage you can use is based on the max input of the tle 2426 rail spliter. OP-AMP you choose, Capacitors and you will need to change the resistor thats in line with the led or the led will burn out. I could give you all the numbers but wheres the fun in that. You really only need to run at 18v, i don't think there is any benefit going higher.

 

[Bassman999]

  That might not work, there is a limit to how high a voltage you can get based on the input voltage and the type of IC used on the board. it might not go all the way to 24v with only 3.7v input but you'll get at least a high enough voltage to be useful.
 
The max voltage you can use is based on the max input of the tle 2426 rail spliter. OP-AMP you choose, Capacitors and you will need to change the resistor thats in line with the led or the led will burn out. I could give you all the numbers but wheres the fun in that. You really only need to run at 18v, i don't think there is any benefit going higher.

I dint think I would go that high anyway, but the choice was up to 12V or up to 25V for the step ups.
Although even at 12-18V I could use a few 3.7V in series for higher Voltage.

 

[bootdsc]

  I dint think I would go that high anyway, but the choice was up to 12V or up to 25V for the step ups.
Although even at 12-18V I could use a few 3.7V in series for higher Voltage.

Don't put them in series, you have to use a special battery protection circuit made for using multiple cells. In fact you cant safely use that type of battery in series or parallel. Has to do with the built in protection circuit not being able to handle the higher voltage or something.

 

[NuClear235]

I will use LiIon accus.
http://www.amazon.de/Lithium-Ionen-14500-Protection-accu-seidel/dp/B005VFP9RI
They have thermal, short circuit and undervoltage deep discharge protection.
 
2x3 cells = 6 x 4,2V = +- 12,6 V. Charging will thru RC model charger.
 
Here is project with external charger adapter:
http://www.head-fi.org/t/586042/what-i-did-next-with-texas-headamp-chip-a-digital-control-desktop-portable

 

[bootdsc]

  I will use LiIon accus.
http://www.amazon.de/Lithium-Ionen-14500-Protection-accu-seidel/dp/B005VFP9RI
They have thermal, short circuit and undervoltage deep discharge protection.
 
2x3 cells = 6 x 4,2V = +- 12,6 V. Charging will thru RC model charger.
 
Here is project with external charger adapter:
http://www.head-fi.org/t/586042/what-i-did-next-with-texas-headamp-chip-a-digital-control-desktop-portable

That projects circuit has no way of monitoring the voltage of each cell when charging and relying on the batteries built in under voltage protection board is also a really bad idea because if you manage to drain the battery to far the protection board will keep you from recharging. 

 

[kaiss3r]

Hi! I am planning to design my own "Cmoybb v2.03r". But I am a little bit confused which "opamp" should i use. Confuse in a way that in their schematic diagram, the opamp used is "OPA2134P". But when what is written in their Bill of Materials, they used "OPA2227". So which is which?

 

[Andymaxwell]

Hi All, I hope this isn't too off topic. I've just bought a CMOYbb to partner my X3 and am looking to experiment with differing sound signatures - with the hope of matching the LO of the X3 (I really like it's sound sig). 
 
@walfredokindly suggested a couple of op amps to try in the CMOYbb, namely JRC4556 and AD712 and some other fine forum member suggested the Lm4562. 
 
However, the AD712 comes in a number of different guises and I can't figure out which one to get. Would someone be able to advise?...
 
http://uk.rs-online.com/web/p/operational-amplifiers/7096152/
http://uk.rs-online.com/web/p/operational-amplifiers/0553589/
http://uk.rs-online.com/web/p/operational-amplifiers/6060121/
 
P.S. To al lus UK buyers, RS components has both the AD712 and LM4562 the JRC4556 seems to only be available on ebay.
And another site to try for op amps is  http://uk.farnell.com.
 
Thank you

 

[TheAlpha]

  Hi All, I hope this isn't too off topic. I've just bought a CMOYbb to partner my X3 and am looking to experiment with differing sound signatures - with the hope of matching the LO of the X3 (I really like it's sound sig). 
 
@walfredokindly suggested a couple of op amps to try in the CMOYbb, namely JRC4556 and AD712 and some other fine forum member suggested the Lm4562. 
 
However, the AD712 comes in a number of different guises and I can't figure out which one to get. Would someone be able to advise?...
 
http://uk.rs-online.com/web/p/operational-amplifiers/7096152/
http://uk.rs-online.com/web/p/operational-amplifiers/0553589/
http://uk.rs-online.com/web/p/operational-amplifiers/6060121/
 
P.S. To al lus UK buyers, RS components has both the AD712 and LM4562 the JRC4556 seems to only be available on ebay.
And another site to try for op amps is  http://uk.farnell.com.
 
Thank you
 
Lol I just bought a cmoy off of BSG on ebay, and I then bought all those chips you listed Lol how ironic and strange eh? lol anyways , I like the ad712, and the Jrc and the LME is really super crisp on highs and mids, the lows are decent and not punchy.
next chips coming through mail that I read on and then ordered are:
ad823an
lme49720na
opa2604ap
opa627b
lm4562na
 
I read somewhere that the above chips are great depending on what headphones you use with them and what gain settings are on your Cmoy, so like you im experimenting as well and really it all comes down to what you like and prefer I guess?
anyone have an opinion on the chips I listed? thanks