[krisjan]

A while back I posted this poll: http://www.head-fi.org/forums/f46/em...h-cmoy-374301/ just to show where i am coming from.

You can see my signature for equipment details...I recently received some opamps from an electronic engineer friend of mine that received it as free samples from texas instruments. In the packet there was 2x 2107's and 2x 2132's. From what I have read thus far I believe the 2132 is not as good as 2227 - but I'll try it out sometime anyway - so I took out the 2227 from my BSG CMOY and inserted the 2107. Now the BSG CMOY is only a single 9v battery, but it does have a jack for DC power supply (up to 15v according to bsg) - so I used a 12v power supply, since I believe the 9v doesn't have quite enough juice for the 2107 (even 12 is apprently a little on the low side). Here's some initial impressions:
ok - first - just for fun, since i bought a multimeter i measured the dc - on the 2227 i got 4.6mv on one channel and 5.5mv on the other, which is acceptable. With the new 2107 in i got -1.3mv and 1.5mv - so a little lower. I also just did a no-source noise test when i turn the amp all the way up. The 2227 for some reason gave some hiss/noise when i turned it way up (maybe there was something wrong with it?) - the 2107 was quiet all the way - in this process i just realized there is some noise when i touch the tin-enclosure of the amp - whenever i adjust the volume knob/touch the enclosure there's this noise that sounds like static - very soft - i realized i heard it with the 2227 on this test but thought it had something to do with the volume adjustment...anyway to avoid this when building a cmoy? maybe isolate the components from casing? it's quite annoying...but at least only discernable when the volume is quite loud.
Then in terms of listening:
First off - there is definitely an immediate improvement - I must agree with majkel and I quote Quote:

OPA2227 - terribly laid back, bass heavy, veiled and slow. Completely not my type

(that's from a thread comparing some cheap opamps...That chip was way to bass heavy, and in a bad way - the sound seemed very muffled/veiled and kind of sluggish. The 2107 sounds much cleaner - listening to a trakc such as smoke city's underwater love my immediate reaction was a "wow!". The bass is impactful and deep but not as overpowering and sluggish.
Just comparing it with the EMU0202's headphone out (I know the cmoy I have might also play a significant part in the sound here) - the sound on my cmoy, now with the 2107 especially, sounds very "analytical" - not too sure if that's the right word - it's hard to describe - there's a lot more detail, especially in terms of transient response, there's more bass, but the EMU sounds sweeter - when listening to things like piano especially (I listened to Alfred Brandel plays Mozart) - the piano sounds more pleasant and perhaps "natural" in a certain sense on the EMU. On the more dynamic material such as pop/rock/exp stuff such as ryoji ikeda i prefer the cmoy...

ok - just initial impressions - i'll post more later as i continue listening. I have ordered parts to build my first CMOY (using the tangentsoft tut) - seems like the best place to start DIY - and then hopefully I will move on to the starving student (I'm mostly a desktop listener - seldom have need for batteries). It seems as if power is quite an issue in all these amps - the more there is the better? especially in terms of bass response and dynamics...

any thoughts?

k

 

[rembrant]

Too bad you didn't post this yesterday. I ordered 4 PCS of opa2132 and 4 of opa2227. Perhaps I would have only gotten 2 of the 2227 and 2 of the 2107. If the 2227 is too slow and mushy for me they will be the first ones to go. what input caps are in your Cmoy?

 

[krisjan]

Quote:

Originally Posted by rembrant /img/forum/go_quote.gif Too bad you didn't post this yesterday. I ordered 4 PCS of opa2132 and 4 of opa2227. Perhaps I would have only gotten 2 of the 2227 and 2 of the 2107. If the 2227 is too slow and mushy for me they will be the first ones to go. what input caps are in your Cmoy?

I'm not too sure of the make - maybe you can recognise them from the pic - details here: Biosciencegeek Headphone Amplifier cMOY Premium Amp - eBay (item 140285073962 end time Nov-28-08 10:45:49 PST)
it's blue box caps - he says it's polypropylene, but i'm not sure of the capacitance,etc. on the cap it says 680n J S and then 63V which is probably the max voltage and then BC and then 2 numbers 0551 and 370...so maybe capacitance is 680nano farad?

 

[millwood]

is the test done sighted or unsighted? in an unsighted test, how accurately do you think you can tell the chips based on their sound?

on the offset: opa227 has a unique bias current cancellation circuitry that I haven't seen in other opamps. because of that, the conventional offset cancellation scheme will actually cause more offset - which may be what you are experiencing.

on the hum: maybe you can ground your amp to the case?

 

[majkel]

Too bad you didn't post this yesterday. I ordered 4 PCS of opa2132 and 4 of opa2227.

As you can see, using Search feature of this forum can save our time and your money.

The aforementioned op-amps were discussed many times, among other better choices.

 

[cfcubed]

Quote:

Originally Posted by majkel /img/forum/go_quote.gif As you can see, using Search feature of this forum can save our time and your money. The aforementioned op-amps were discussed many times, among other better choices.

Yes & I've bookmarked one of your posts on the topic

Although a bit dated now, Tangent has some good info and although perhaps not directly relevant, this thread has some interesting info.

BTW, of the opamps I've tried in SOHAs the OPA2107 is my fav but it is not the easiest to find...

 

[krisjan]

Quote:

Originally Posted by millwood /img/forum/go_quote.gif is the test done sighted or unsighted? in an unsighted test, how accurately do you think you can tell the chips based on their sound? on the offset: opa227 has a unique bias current cancellation circuitry that I haven't seen in other opamps. because of that, the conventional offset cancellation scheme will actually cause more offset - which may be what you are experiencing. on the hum: maybe you can ground your amp to the case?

the test is not blind - but please, there is a huge difference in sound, and it's defn. not in terms of being predisposed based on other opinions. I've read so many posts and heard so many "opinions" that the EMU0202 headphone out will never come close to a seperate headphone amp (such as cmoy thru the line-out), but i'm sorry it still sounds great to me - and better than the cmoy on some genres...the opa2227 sounded terrible - maybe mine was a bit of a dud, or damaged - i wish i had another one to test - but nevertheless, now is the first time i actually enjoy this cmoy (with 2107)

 

[krisjan]

Too bad you didn't post this yesterday. I ordered 4 PCS of opa2132 and 4 of opa2227. Quote:

As you can see, using Search feature of this forum can save our time and your money. The aforementioned op-amps were discussed many times, among other better choices.

such a pity the search feature of this forum really sucks - it's better to use google - first links that pop-up is usually head-fi...

 

[Pars]

If you use the search at the top of the forum, there is a Google search in there restricted to head-fi (I believe). Works much better.

 

[millwood]

Quote:

Originally Posted by krisjan /img/forum/go_quote.gif the test is not blind - but please, there is a huge difference in sound, and it's defn. not in terms of being predisposed based on other opinions.

it is tough to be definitive when you have no empirical data.

I was recently in a conversation when someone said his headphone amp sounded great, only to find out that the pins on his output transistor were reversed.

or another person who insisted that his amp sounded louder, only to learn that he had lowered the gain by close to 4db.

or a couple others who praised their superior sounding amp, only to learn that they were oscillating like crazy.

that's why blind listening tests were invented,

.

so take the listening test I linked for you here (http://www.klippel-listeningtest.de/...tructions.html) and show us how you do on that test.

you may learn a thing or two about your hearing.

 

[krisjan]

Quote:

Originally Posted by millwood /img/forum/go_quote.gif it is tough to be definitive when you have no empirical data. I was recently in a conversation when someone said his headphone amp sounded great, only to find out that the pins on his output transistor were reversed. or another person who insisted that his amp sounded louder, only to learn that he had lowered the gain by close to 4db. or a couple others who praised their superior sounding amp, only to learn that they were oscillating like crazy. that's why blind listening tests were invented, . so take the listening test I linked for you here (Listening Test - Instructions) and show us how you do on that test. you may learn a thing or two about your hearing.

ok, let's talk about this whole "extremist" empirical angle for a mo. it's not that i have anything against dong blind tests etc. but i think it's taken to an extreme at times - i mean, why don't we go all the way to the point where we just test audio equipment with ultra-accurate measurement devices, and then sit back and say "now that's a great opamp/headphone" without ever listening to it...you see the problem is, in the end it's humans listening to the gear, not machines - and wether i know the number of an opamp, it doesn't make a difference to me - i listen to the sound...and guess what ten different people will have ten different opinions - and then i don't care whether the output transistor pins are reversed, the amp is oscillating like crazy, or whatever - if a tree falls in the forest and no one hears/sees it, does it matter (to us) - if such a person then hears a "better" working amp then great - it doesn't matter wether they are blind at that moment or not...i also believe in tests over time as opposed to single high-intensity blind sessions, because there are certain psychological principles at work with blind tests which put people in "stressed" unnatural state of mind which has an effect on what you hear...

sorry - i'm not attacking anybody here, but audio, and the enjoyment there-of is VERY subjective - so there is a definite limit to an empirical approach...

k

 

[millwood]

Quote:

Originally Posted by krisjan /img/forum/go_quote.gif in the end it's humans listening to the gear, not machines - and wether i know the number of an opamp, it doesn't make a difference to me - i listen to the sound...

isn't that why people do blind listening, rather than measurements, to judge sound quality?

Quote:

if such a person then hears a "better" working amp then great - it doesn't matter wether they are blind at that moment or not...

there is some logic to that, for sure.

Quote:

i also believe in tests over time as opposed to single high-intensity blind sessions,

so take the klippel test as many times as you want, whenever you want it.

Quote:

so there is a definite limit to an empirical approach...

there is a definite limit to any approach. That deson't mean such an approach is invalid.

 

[rembrant]

Too bad you didn't post this yesterday. I ordered 4 PCS of opa2132 and 4 of opa2227. Quote:

As you can see, using Search feature of this forum can save our time and your money. The aforementioned op-amps were discussed many times, among other better choices.

Heh you assume much sir. I did do a search and was lead to a topic with a poll that indicated that most people proffered the 2227.

Head-Fi: Covering Headphones, Earphones and Portable Audio - View Poll Results Hmm ironic that that is the same thread your talking about is it not?

 

[millwood]

Quote:

Originally Posted by rembrant /img/forum/go_quote.gif Heh you assume much sir. I did do a search and was lead to a topic with a poll that indicated that most people proffered the 2227. Head-Fi: Covering Headphones, Earphones and Portable Audio - View Poll Results Hmm ironic that that is the same thread your talking about is it not?

it simply shows you how unreliable our hearing is and how powerful the desire to conform is.

 

[majkel]

Quote:

Originally Posted by millwood /img/forum/go_quote.gif it simply shows you how unreliable our hearing is and how powerful the desire to conform is.

It just depends on the actual sound quality of the components people use, starting from the source and ending at the headphones. Some op-amps just don't fit low-voltage, low-impedance-load portable applications. For Cmoy, the best are: TLE2072, TLE2082 (cheap, work very well), AD8397 (much juice but power hungry), AD8620, AD8066 if you like the sound. OPA2228 if the gain is >=5 or you compensate it, sounds better than the AD8066.

Regarding more desktop applications. OPA2107 sounds simply worse than similarily priced and designed OPA2111. The last one is amongst the best dual op-amps but not perfect. I prefer OPA2228P and statistics saying AD8066 is better are just funny to me. I don't use AD8065/AD8066 for audio any more. The OPA2227 is ridiculously bad. Actually, I care for no op-amps but a few these days: AD797BRZ, AD8022, AD8021, LME49720, AD8599, OPA2228P. And the AD797BRZ is the only one I could say transparent and not sounding like op-amp. The AD8022 maybe, too but is a bit nasty.