[majkel]

OPA2137 is great when stable. I had problems with the OPA2137 in one of my headphone amps so I left it alone. But when stable, I like it very much. It's pretty confusing that such a slow op-amp produces artifacts, i.e. on piano notes being obvious it's instability. AD8066 is interesting for bass alone. Otherwise, you can use the AD8599 for instance.

 

[digger945]

Quote:

joshatdot, you could diy adapters, see here: http://www.headphoneamp.co.kr/ftp/si.../Tip/SMD-4.jpg

yup, browndogs are expensive as hell... first you think 'only 3$ per piece'.. but you have to order alot of them.

I recently got on a opamp buying spree... I already have or will receive:
NE5532
LM6172
LM4562
OPA2107
OPA2604
OPA2227
OPA2132
NJM4556
AD8066
AD823
AD843
AD744
AD8620
RC4558

now I just have to order parts for my pimeta (board has already arrived) and compare them & write a review here

fortney: considering opamps, I think a long time listening test is more suitable. I must say, short-time a/b-ing seems inferior to me. well, except if it's a very clear difference between two opamps

majkel: you seem to have a non-standard opamp liking. would you care to explain which opamps you like and why?
Filburt also seems to have a quite different oppinion about popular opamps, would be nice if he'd posted in here too

I have some RC4558s. The JRC4558 is used in my NAD 1130 preamp, which was one of my very first headphone amps. I still really like listening to it, and it's fun to play around with the bass and treble. I think nikongod uses JRC4556s in his balanced cmoy.
 

 

[HAWK1111]

I see that your post is years old, however I am having a cmoy amp built and wanted to know if the AD825 is still the best chip to use. I like punchy, hard hitting bass, very detailed mids & highs. Great soundstage. I listen to mostly hard rock. Looking at your detailed  reviews of all those chips, I am undecided on the following chips; AD8066, AD8620, TLE2082, TLE2142, AD8397, or AD825
I am very new to this and would appreciate your advice. I am not sure if this would affect your recommendation, but I will be using Koss Portapro headphones with the following specs; 15-25,000Hz, Impedance 60 ohms, sensitivity 101 dB SPL
 
Thank You 

 

[ElephantAudio]

Any thoughts on the OPA 2111 Dual Low Noise Precision Difet Operational Amplifier audio chip? OPA2111
It is suggested as better than NE5532. I'm not a technician at all and wish to know if can be use on cMoy v2.03?

 

[stv014]

Quote:

Any thoughts on the OPA 2111 Dual Low Noise Precision Difet Operational Amplifier audio chip? OPA2111
It is suggested as better than NE5532.

 
Not really, it is noisier, has much lower GBWP, and much higher open loop output impedance. It is probably not great for driving a low impedance headphone load.
If you can get the NJM4556, I would recommend it, using the lowest gain that is sufficient; it can output up to 100 mA current, drives low impedance loads well, is stable (no output resistor is needed), and costs less than $1.

 

[Tommy Thong]

i tried with LM4562Na, sounds perfect on high and details, tight-bass

 

[guanglier]

Hi guys !
 
I'm really surprised to see your replies concerning the op amps !!
 
could someone describe the setup ?
 signal source (with THD)
 headphone used
 impedance and THD of the headphone.
 
 
why ?
because i see that this op amp is bad, this one is marvelous... am i the only one to find this wierd ?
 
example : it has been said that OPA2227 is aweful... but !  with 3nv/SHz this is an awesome performance ! moreover channel separation is 138dB ! but the main thing is the THD (total harmonic distortion), at 1Khz it's 0.00005 % !!!!!!!!!!!!  (3.5V rms) how could you ear that ?
 
So why this marvelous op amp isn't able to drive correctly headphones ? maybe the problem is not the OP amp !!
 
have a look at impedance of the headphone vs frequency, its wery non linear. considering the fact that these op cannot supply so much current, there are frequencies where sound is well amplified and many other frequencies where it is not. Example : sennheiser HD650, 300ohms at 10hz, 490 ohms at 100hz, 310 ohms at 2khz ... so the point is : non linear load, weak op amp -> uncertain results.
 
That's why the sound is so different from differents op amp : each smal technical characteristic is amplified by the difficulties for the op amp to drive. In electronic it's a way for disaster.
 
my conclusion : the CMoy is a bad amp, the op amp is not a concern.
 
a final power stage is needed for the headphone amp to work correctly. Think about headphones with 45 ohm impedance, what's the difference wetween your sound card and this weak amp ? this poor op amp cannot supply the 45 ohms headphones ! ! that's not a power amp !
 
one good headphone final stage can be found here (this is NOT my schematic)
http://electroschematics.com/wp-content/uploads/2009/06/hifi-headphone-amplifier.gif
 
in this case, the op amp compensates for the conduction gap of the transistors, and ensure minimum THD when transistors ensure power. to improve you need condensators in  // with diodes, but that's another topic.
 
I'm open to discuss more.

 

[james tayao]

Hi everyone... I'm new here and also to headphone amps... I was able to try the JRC 4565 yesterday (these came from an old Creative Viba sound card)... not yet fully tested... but is working using sine waves... will try them today using different loads and different frequency...
 
also I came upon another opamp the M5216 (from a creative SB 5.1 live sound card)... data sheet indicates it's best for portable headphone amps they have curves for 32ohm loads... has anyone tried them?

 

[guanglier]

hi,
can't find the part "m5216" or "NJM5216", is the ref correct ?
 
Anyway the opamp like JRC 4565 is just an opamp, not a poweramp !
 
what is the impedance of your headphones ?

 

[james tayao]

hi,
can't find the part "m5216" or "NJM5216", is the ref correct ?

Anyway the opamp like JRC 4565 is just an opamp, not a poweramp !

what is the impedance of your headphones ?

Yes, m5216 is correct, i just googled it and found the datasheet somewhere.. its made by panasonic.
I got it to work now using a different circuit
.. cmoy circuit does not work well for me..
I'm am using a 32 ohm TDK HP.

 

[guanglier]

the cmoy is not a good amp. That's my point of view.
 

 

[Synthax]

Which one do you can advise for CMoy bb 9V to got: very wide soundstage, analog deep bass, and not as exposed heights as with OPA2227

 

[guanglier]

the OPA 2227 THD is 0.00005% !!!!!
could you ear the distortions of the bass ??

 

[Magicman74]

My favorite Duals
LM4562   LT1364

 

[Synthax]

Well, maybe it is not a metter of bass perception, but I hope you agree that the op-amps change the sound characteristic.