Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › Best sounding cheep op-amp for CMoy's? OPA2227, OPA2228, AD8066...other?
New Posts  All Forums:Forum Nav:

Best sounding cheep op-amp for CMoy's? OPA2227, OPA2228, AD8066...other? - Page 7

post #91 of 102
Quote:
Originally Posted by Bassman999 View Post
 

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.

post #92 of 102
Quote:
Originally Posted by Bassman999 View Post
 

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.

post #93 of 102

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

post #94 of 102
Quote:
Originally Posted by bootdsc View Post
 

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.

post #95 of 102
Quote:
Originally Posted by bootdsc View Post
 

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..USB LiIon/LiPoly charger

Simple and cheap

post #96 of 102

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.


Edited by bootdsc - 4/6/14 at 1:06am
post #97 of 102

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

post #98 of 102

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.

post #99 of 102
Quote:
Originally Posted by bootdsc View Post
 

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.

post #100 of 102
Quote:
Originally Posted by Bassman999 View Post
 

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.


Edited by bootdsc - 4/7/14 at 2:15am
post #101 of 102

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


Edited by NuClear235 - 4/7/14 at 6:08am
post #102 of 102
Quote:
Originally Posted by NuClear235 View Post
 

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. 

New Posts  All Forums:Forum Nav:
  Return Home
Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › Best sounding cheep op-amp for CMoy's? OPA2227, OPA2228, AD8066...other?