# Anyone tried the OPA 2111 ?



## PinkFloyd

Seems there is nothing about the OPA 2111 on Head-Fi even though it seems an ideal substutute for the likes of the OPA2132 / 2604 etc.

 details here: http://focus.ti.com/docs/prod/folder...t/opa2111.html

 Comments on its use in place of a OPA2132 appreciated 
	

	
	
		
		

		
			





 Pinkie.


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## PinkFloyd

Surely someone here has got experience of this op amp?


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## morsel

A quick glance at the pdf shows the OPA2111 to be a laser trimmed DIFET opamp suitable for professional audio equipment. This would seem to be a good omen, however, the rated output current is only 10mA, which definitely rules it out for any direct drive applications, such as a cmoy. It is pricy, at $12 a pop. Has anyone listened to this opamp as an input stage?


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## PinkFloyd

I couldn't wait for feedback and I popped the 2111 into the Chiarra headphone amp and WOW! I really mean "WOW" I thought I was hallucinating, the headphones "disappeared" and the sound is just so airy and effortless with this Op amp on board. 

 Slighty less of a WOW factor compared to the OPA 2107, which is absolutely breathtaking in the Chiarra, but the 2111 is a MAJOR improvement over the OPA 2132 / 2604 / 2227 / 2228/ 2134/ and the AD823 / 712

 I'm surprised there isn't any info on the 2111 on head-fi cause it's a magical sounding OP amp (in the chiarra anyways) it may be expensive but boy does it sound good!

 Pinkie.


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## Dan the audioman

Just out of curiosity...how do you think it would sound in a PIMETA?


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## Magic77

Quote:


 _Originally posted by Dan the audioman _
*Just out of curiosity...how do you think it would sound in a PIMETA? * 
 

I guess someone will have to give it a try first. I just may order these OPA2111's and try them out for myself.


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## Dan the audioman

Hey Magic77, 

 Let me know what it sounds like in the PIMETA. thanks

 -Dan


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## ADS

I just ordered one for my PIMETA. I'll let you all know how it sounds.


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## Dan the audioman

great. thanks.

 Dan


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## ADS

I'm slightly worried about the slow slew rate (2V/us compared to 20V/us for the OPA134). I'll see what I think when I get it though.


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## IMEP

Quote:


 _Originally posted by ADS _
*I'm slightly worried about the slow slew rate (2V/us compared to 20V/us for the OPA134). I'll see what I think when I get it though. * 
 

I'm tempted to try this opamp but, I also question the slow slew rate. 

 Has anyone else given this opamp a try?


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## ADS

I still haven't received the opamp, but after looking over the spec sheets a little more I'm pretty sure it's going to be pretty terrible. The settling time is slooooow, something like 12 times as slow as the AD823AN I'm using now, and the slew rate is nearly as bad (10 times less than the AD823AN). Noise levels are decent, but nothing better than any other opamp. Output current and output voltage are both rather low. In all honesty I see nothing that would make this opamp sound good. I guess I'll find out though, should be here soon.


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## KTpG

Any comparisons with OPA637BP (ya BP, not AP)? I have two of these laying around waiting my new amp to be finished... when I get motivated enough.


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## PinkFloyd

Quote:


 _Originally posted by ADS _
*I still haven't received the opamp, but after looking over the spec sheets a little more I'm pretty sure it's going to be pretty terrible. The settling time is slooooow, something like 12 times as slow as the AD823AN I'm using now, and the slew rate is nearly as bad (10 times less than the AD823AN). Noise levels are decent, but nothing better than any other opamp. Output current and output voltage are both rather low. In all honesty I see nothing that would make this opamp sound good. I guess I'll find out though, should be here soon. 
	

	
	
		
		

		
		
	


	


* 
 

What looks good on paper doesn't necessarily equate to good sound........... If the 2111 performs in your amp the way it performs in the Chiarra be prepared for a very welcome surprise indeed


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## PeterR

Quote:


 _Originally posted by ADS _
*I still haven't received the opamp, but after looking over the spec sheets a little more I'm pretty sure it's going to be pretty terrible. The settling time is slooooow, something like 12 times as slow as the AD823AN I'm using now, and the slew rate is nearly as bad (10 times less than the AD823AN). Noise levels are decent, but nothing better than any other opamp. Output current and output voltage are both rather low. In all honesty I see nothing that would make this opamp sound good. I guess I'll find out though, should be here soon. 
	

	
	
		
		

		
		
	


	


* 
 

Hmm. So how much slew rate do you need? The output can swing +/-11V max, so a 2V/µs slew limit means it can put out 7.8 Vrms (with a buffer at the output that's enough for 120dB from HD-600s...) up to 29kHz.


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## IMEP

In my never ending quest for knowledge, I just re-read the HeadWize paper titled "Designing an OPamp Headphone Amplifier". On page 2 it recommends a slew rate of 5uV/sec or more. If this is a good rule of thumb, the 2111s slew rate of 2V/uS would be more than enough. Right?? 

 Is the HeadWize article's 5uV/sec sugestion correct or a misprint? 5uV/sec seems really slow to me, but what do I know! 
	

	
	
		
		

		
			




 IMEP

 Edited: Removed my erroneous decimal conversion


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## Magic77

I'm no expert on Slew Rates; but maybe op-amps with very high slew rates are not really necessary for headphone amps?

 Another words; a high slew rate is ok, but it may or may not yield better quality sound or performance?

 I think we may need a "Slew Rate" Thread.


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## PeterR

Quote:


 _Originally posted by IMEP _
*In my never ending quest for knowledge, I just re-read the HeadWize paper titled "Designing an OPamp Headphone Amplifier". On page 2 it recommends a slew rate of 5uV/sec or more. If this is a good rule of thumb, the 2111s slew rate of 2V/uS (2000V/sec) would be more than enough. 

 Is the HeadWize article's 5uV/sec sugestion correct or a misprint? 5uV/sec seems really slow to me, but what do I know! 
	

	
	
		
		

		
		
	


	



 IMEP * 
 

µ=micro=1e-6, 2V/µs=2,000,000V/s
 At 5µV/s it would take the amp over two days to swing up to 1V, a tad too serene perhaps...


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## PinkFloyd

Quote:


 _Originally posted by Magic77 _
*I'm no expert on Slew Rates; but maybe op-amps with very high slew rates are not really necessary for headphone amps?

 Another words; a high slew rate is ok, but it may or may not yield better quality sound or performance?

 I think we may need a "Slew Rate" Thread. 
	

	
	
		
		

		
		
	


	


* 
 

It depends on the application the Op amp is used for Magic77 but measurements count for screw all when music is involved. Something that measures absolutely dire can sound absolutely breathtaking whereas something that measures perfectly can sound utter crap.

 Musical appreciation can be measured by one thing (two things actually) your ears. So much of todays equipment is designed purely by measurement alone...... if it "plots" well it goes into production. In the halcion days of Hi-Fi mathematics made up 90% of the design, the remaining 10% involved months (even years) of tweaking and honing to get the sound just "right"

 It's NEVER a good idea to employ a component in a design in the final "listening tests" on the merit of "it measures well" The traditional designer was not afraid to use his ears. In the case of the 2111 "my" ears tell me it is the best op amp for the Chiarra amp as it sounds fantastic. I don't give a flying screw what the spec sheets say, this op amp is my choice in my amp.

 Let's get back to the trial and error design approach with Hi-Fi and stop regarding TI spec sheets as the bible to audio Nirvana cause good sounding equipment is not something that can be produced by soldering a few "perfectly" measured components together. 

 Use your ears 
	

	
	
		
		

		
		
	


	




 Pinkie.


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## rickcr42

Quote:


 I'm no expert on Slew Rates; but maybe op-amps with very high slew rates are not really necessary for headphone amps? 
 

correct , though everyone seems spec sheet sensitive it comes down to listening 

 i have used the PMI/AD OP27 in many audio stages and from memory it is a 3V/uSEC slew rate .

 it sounds just fine-especially with a discrete output stage for higher current .

 another point worth consideration is high speed layout is not that simple , sometimes slower is actually better and settling time is far to often an overlooked spec


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## IMEP

Quote:


 _Originally posted by PeterR _
*µ=micro=1e-6, 2V/µs=2,000,000V/s
 At 5µV/s it would take the amp over two days to swing up to 1V, a tad too serene perhaps... * 
 

Thanks for correcting my error. I must have had "mili" on the brain. Sorry for the confusion. Actually, we went to my wife's cousin's home for lunch/dinner. At the table (bored of course) I was mulling the conversion over in my head and realized I made a mistake. I was hoping I would get back home and correct it before anyone noticed! 
	

	
	
		
		

		
		
	


	




 No such luck!

 Edited: Regarding the HeadWize article's =/> 5uV/s slew rate recommendation - I guess you can't always believe what you read!


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## ADS

Quote:


 _Originally posted by rickcr42 _
*correct , though everyone seems spec sheet sensitive it comes down to listening 

 i have used the PMI/AD OP27 in many audio stages and from memory it is a 3V/uSEC slew rate .

 it sounds just fine-especially with a discrete output stage for higher current .

 another point woth consideration is high speed layout is not that simple , sometimes slower is actually better and settling time is far to often an overlooked spec * 
 

Agreed, and I was hoping that the slower slew rate would mean a much better settling time which could do wonders for smoothing out treble response, but the settling rate is 12 times slower. I'm not passing judment on this amp until I hear it of course, and it should be hear the 23rd. I'll tell you all what I think of it when I get it.


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## IMEP

Quote:


 _Originally posted by PinkFloyd _
*It depends on the application the Op amp is used for Magic77 but measurements count for screw all when music is involved. Something that measures absolutely dire can sound absolutely breathtaking whereas something that measures perfectly can sound utter crap.

 Musical appreciation can be measured by one thing (two things actually) your ears. So much of todays equipment is designed purely by measurement alone...... if it "plots" well it goes into production. In the halcion days of Hi-Fi mathematics made up 90% of the design, the remaining 10% involved months (even years) of tweaking and honing to get the sound just "right"

 It's NEVER a good idea to employ a component in a design in the final "listening tests" on the merit of "it measures well" The traditional designer was not afraid to use his ears. In the case of the 2111 "my" ears tell me it is the best op amp for the Chiarra amp as it sounds fantastic. I don't give a flying screw what the spec sheets say, this op amp is my choice in my amp.

 Let's get back to the trial and error design approach with Hi-Fi and stop regarding TI spec sheets as the bible to audio Nirvana cause good sounding equipment is not something that can be produced by soldering a few "perfectly" measured components together. 

 Use your ears 
	

	
	
		
		

		
		
	


	




 Pinkie. * 
 

Hi Pinkie,
 I didn't mean to offend you with my posts. I respect your opinions and knowledge of headphone amps. Your original post is what made me look closer at the OPA2111.

 I completely agree that a spec sheet can't tell you how an opamp will sound. It does however tell you how it performs electronically; which should give you a rough idea how it will perform sonically.

 Like I said, I respect your opinions and your audio knowledge, but your (or anybody’s) personal impressions of a devices sonic quality is subjective. What you may consider sounds "dark" or "bright" others may consider differently. 

 A spec sheet on the other hand is pretty darn objective. I am trying to better understand what is and isn't important when reading an opamps spec sheet. When I compared the 2111 specs with the AD8620 the difference in slew rates was one of the things that jumped out at me. I am pretty sure an opamps slew rate has some sort of sonic effect. What I don't know yet is what is the minimum slew rate for good sound and at what point it's a matter of diminishing returns (or even detrimental). Hence my posts.

 I am pretty much a mechanical guy with very limited "sparky" experience, so please forgive my ignorance. This hobby is great way for me to learn more about electronics and have lots of fun to boot!! 

 No harm, no foul? As always, I will continue to look forward to reading more of your opinions and impressions.

 IMEP


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## ADS

Well, if we assume that we're all listening to redbook CD, we have 44,100 discrete voltage levels per second, and lets say we want to be able to swing from 0V to 12 V in a single sample. To do that we'll need a slew rate of:

 12/(1/44100)= 0.5292 V/usec

 OPA2111's slew rate=2 V/usec

 This means that the OPA2111 should be just fine. Now let's say that we want the output to have settled before the next sample. Within the OPA2111 specs we find the following:

 To settle to 0.1%: 6 usec
 To settle to 0.01%: 10 usec

 A single sample takes about 22.67 usec, which would mean that if the slew rate was infinite the output would always have settled down by the next sample, but due to the fact that the slew rate is not really perfect, it is possible that at high frequencies/output levels the voltage output will not have settled by the time the next sample comes around. What this means in terms of audible effects, I have no idea. 
	

	
	
		
		

		
		
	


	




 If someone could tell me that would be wonderful. I'm guessing that this means that you may get some high frequency sibilance/distortion if you drive the opamp too hard. At half the volume (6V, which I think is plenty to drive most headphones) none of these problems exist. I guess the conclusion to this long rambling post is that yes, in extreme cases the OPA2111 may be too slow, for most uses it's just fine. I can't wait to hear it.


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## rickcr42

ADS-funny thing about specs is they can tell you if something sucks if the specs are _really bad_ or the noise figure is high and the application is fopr low noise and high gain (mic or mc amps) but can never tell you if something spounds good

 as for speed ,it is not all it is cracked up to be-some very "slow" tube amps with limited bandwidth sound very convincing while a some state of the art (specs ) can sound very uninspiring.
 I guess that is why we listen

 BTW-I can remember the TL072/LF357 being called the "ultimate" opamp and we would not even consider its use now unless for a musical instrument effect .

 In fact I beleive the LF357 was the Van Alstine 'secret" opamp upgrade for the original Dynaco PAT-4 preamp and the reviewers all touted the quantum leap forward in sound !

 It also depends on system matching what will or will not sound good

 for example the often disregarded OP275 will sound great in a system with a light bottom end but sound bloated and dull in a bass heavy system.The '275 also has a nice settling time

 system integration is more important than flavor of the week or the ultimate spec


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## ADS

In a little addition to my above post, here's the time required for the OPA2111 to settle in a discrete voltage sample at maximum extension (12 V and redbook CD just like before)

 (12 V) / (2 V/usec) = 6 usec

 To reach 0.1%=12 usec
 To reach 0.01%=16 usec

 Since the time between samples is 22.67 usec it looks like the OPA2111 has plenty of headroom for what we're going to do with it, even at levels it's unlikely to ever see so the possibility I mentioned in my previous post of high frequency problems won't happen. Conclusion? I guess that we're all using parts that are way too fast.


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## rickcr42

if it measures good and sounds bad, it is bad; if it measures bad and sounds good, you have measured the wrong thing." 

 - Daniel R. von Recklinghausen,
 former Chief Research Engineer, H.H. Scott


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## PeterR

Quote:


 _Originally posted by ADS _
*Well, if we assume that we're all listening to redbook CD, we have 44,100 discrete voltage levels per second, and lets say we want to be able to swing from 0V to 12 V in a single sample. To do that we'll need a slew rate of:

 12/(1/44100)= 0.5292 V/usec

 OPA2111's slew rate=2 V/usec *
*


Okay, first of all the output of your CD player doesn't look like discrete steps (neglecting for a moment sake induced esoteric DACs by designers who decided reconstruction filters are for wimps, but even in this case you wouldn't necessarily want to reproduce them). You need to look at the waveform of the signal you want to reproduce. The steepest slope of a sinewave is Vpk*2*Pi*f, so for the CD's 20kHz upper limit and 12V you'd need a slew rate of 1.5V/µs.

 Settling time is the time it takes the output of the amp to settle to a value within a certain percentage of the target value when you apply a step signal at the input.
 So in this case, if you instantaneously change the input from 0V to 10V, the amp will try to change its output as fast as its slew limit allows to -10V (G=-1). At 2V/µS this takes 5µS. The output may then overshoot (could be also seen in the frequency response) and you'd have a damped oscillation around the final value. The 2111 needs an additional 1µS for its output to stay within 10mV of -10V. For our application, this figure is pretty insignificant.*


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## PeterR

Quote:


 _Originally posted by ADS _
 Agreed, and I was hoping that the slower slew rate would mean a much better settling time (...) 
 

Slew time is included in the settling time. Slower slew rate -> longer settling time (all else being equal).


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## bigcat39

Heh, I work for a really major research lab .... as in 100+ EE PhD level researchers. About half of them are analog guys. (BTW, I'm a metrologist, so I really BELIEVE in measurements). The engineers I have shared my plans for PPA building with are all intrigued by the circuit .... and totally mystified by the super high performance opamps we all choose. Anything you can't measure is indistinguishable from magic ... and there has never been an instrument devised, IMHO, that can tell what an audio circuit will sound like subjectivly.
 It's interesting to get insights from all this high priced talent (You should hear what they say about super expensive power cables for high end audio 
	

	
	
		
		

		
		
	


	




 ), but I their advice all boils down to one thing: I'm going to let my ears be my guide. I have made a lot of electronic measurements over the years, and how an audio circuit behaves is often unrelated to anything you can measure. Measurements, even those made by the manufacturer, follow the laws of uncertainty. What they don't tell you in spec sheets is that sometimes the uncertainty of the measurement is LARGER than the measurement itself. What is important is PERFORMANCE, relative to the ears to be stimulated.


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## PinkFloyd

Quote:


 _Originally posted by IMEP _
*Hi Pinkie,
 I didn't mean to offend you with my posts. I respect your opinions and knowledge of headphone amps. Your original post is what made me look closer at the OPA2111.

 I completely agree that a spec sheet can't tell you how an opamp will sound. It does however tell you how it performs electronically; which should give you a rough idea how it will perform sonically.

 Like I said, I respect your opinions and your audio knowledge, but your (or anybody’s) personal impressions of a devices sonic quality is subjective. What you may consider sounds "dark" or "bright" others may consider differently. 

 A spec sheet on the other hand is pretty darn objective. I am trying to better understand what is and isn't important when reading an opamps spec sheet. When I compared the 2111 specs with the AD8620 the difference in slew rates was one of the things that jumped out at me. I am pretty sure an opamps slew rate has some sort of sonic effect. What I don't know yet is what is the minimum slew rate for good sound and at what point it's a matter of diminishing returns (or even detrimental). Hence my posts.

 I am pretty much a mechanical guy with very limited "sparky" experience, so please forgive my ignorance. This hobby is great way for me to learn more about electronics and have lots of fun to boot!! 

 No harm, no foul? As always, I will continue to look forward to reading more of your opinions and impressions.

 IMEP * 
 

???? I'm not offended by anything?? I was just saying to myself that I don't care what the spec sheets say cause the 2111 sounds great in the application I'm using it in. Looks like my comments were read out of context...... again


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## ADS

Well, just received my OPA2111 and popped it into my PIMETA. It's burning in now, but my initial reaction is WOW! Tight, deep, powerful bass and liquid smooth treble. Compared to my AD823 this is a major improvement. Larger soundstage, smoother treble, and amazing bass. I really recommend this chip to anyone looking to replace their OPA2134 or AD823. I'll post updated impressions in a bit, but right now I can definitely say that this opamp is a superb match for my DT880s. Thank you PinkFloyd.


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## ITZBITZ

Well, I got some 2111's today with my parts order. I must say, in a CMOY, I'm not impressed. 

 The 2107 sounds much cleaner, close to the 2132P/PA. But the 2111 sounds deep in the bass, but very low in the treble. I would say the hi end seems vacant with the 2111. This is only with 18V (+/- 9V) and the 2111 indicates a minimum +/- 10V on the sheet, so I'll try it with more juice later.

 I haven't tried it in the PIMETA yet, but since it's a buffered output, I would guess it might sound better since it's not driving the load directly. We'll see when I get the time for that.

 I'm impressed by the 2107 in the CMOY, almost beyond what you get with the 2132 in that setup. The 2111 just didn't cut it though.

 Of course, these all pale compared to the 637/627 PPA setup, but that's obviously two different levels of technology.


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## ADS

Quote:


 _Originally posted by ITZBITZ _
*Well, I got some 2111's today with my parts order. I must say, in a CMOY, I'm not impressed. 

 The 2107 sounds much cleaner, close to the 2132P/PA. But the 2111 sounds deep in the bass, but very low in the treble. I would say the hi end seems vacant with the 2111. This is only with 18V (+/- 9V) and the 2111 indicates a minimum +/- 10V on the sheet, so I'll try it with more juice later.

 I haven't tried it in the PIMETA yet, but since it's a buffered output, I would guess it might sound better since it's not driving the load directly. We'll see when I get the time for that.

 I'm impressed by the 2107 in the CMOY, almost beyond what you get with the 2132 in that setup. The 2111 just didn't cut it though.

 Of course, these all pale compared to the 637/627 PPA setup, but that's obviously two different levels of technology. * 
 

The OPA2111 has a really really low output current capability, so using it in a cmoy is not a very good idea. Try it in the PIMETA, it's lightyears better than the OPA2312 when buffered. 
	

	
	
		
		

		
		
	


	




 *EDIT* The minimum supply voltage is +/- 5V, not +/- 10V


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## Nigel

Hi,

 I purchased the OPA 2111 & OPA 2107 from Mr Floyd for my Chiara. They will be replacing my current favourite, OPA 2132. Anyway, with regard to the OPA 2111, I conclude with some of the postings on this thread. For instance, massive soundstage the biggest I've yet heard whilst listening to headphones. Very good musical detail retrieval, yet presented in an extremely smooth fashion. Deep bass, not too sure about it's timing qualities though, maybe there's a degree of overhang. Strange, but it seems that songs are lasting longer. Donald Fagen's "Ruby Baby" lasted about twenty minutes.  

 An extremely warm sounding chip this one. However, when it comes to the treble...... it's as if you've installed some tone controls & turned the treble right down. The treble becomes very warm & looses a lot of it's sparkle. Tonally very different to anything I'd heard before. Maybe the presentation could be classed as 'valve like.' It's strange, the 2107 sounds very tonally similiar to the 2132 but slightly better, but the 2111 is very different. On the other hand, I can hear certain details on recordings, via the 2111, but not on the 2107. Which is weird with it being less brightly lit. Also, when your listening to the 2107 you kinda want to see how the recording would sound on the 2111 which probably means I'm still not sure. It's as if it does some things brilliantly but lacks the ability to present a true sonic picture, maybe it's a flawed gem.

 I've spoke about sound qualities not musical qualities so I'll post again in a couple of weeks when I've had more listening time & see if the 2111 truly engages my emotions. Also, maybe it needs more than just a couple of days burn-in period to show it's complete best.


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## Nigel

Oh, I forgot to mention - thank you Mike for 'discovering' the OPA 2111. It's good to know your still trying to squeeze every drop of musical juice out of that little Chiara.


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## ADS

Quote:


 _Originally posted by Nigel _
*Hi,

 I purchased the OPA 2111 & OPA 2107 from Mr Floyd for my Chiara. They will be replacing my current favourite, OPA 2132. Anyway, with regard to the OPA 2111, I conclude with some of the postings on this thread. For instance, massive soundstage the biggest I've yet heard whilst listening to headphones. Very good musical detail retrieval, yet presented in an extremely smooth fashion. Deep bass, not too sure about it's timing qualities though, maybe there's a degree of overhang. Strange, but it seems that songs are lasting longer. Donald Fagen's "Ruby Baby" lasted about twenty minutes.  

 An extremely warm sounding chip this one. However, when it comes to the treble...... it's as if you've installed some tone controls & turned the treble right down. The treble becomes very warm & looses a lot of it's sparkle. Tonally very different to anything I'd heard before. Maybe the presentation could be classed as 'valve like.' It's strange, the 2107 sounds very tonally similiar to the 2132 but slightly better, but the 2111 is very different. On the other hand, I can hear certain details on recordings, via the 2111, but not on the 2107. Which is weird with it being less brightly lit. Also, when your listening to the 2107 you kinda want to see how the recording would sound on the 2111 which probably means I'm still not sure. It's as if it does some things brilliantly but lacks the ability to present a true sonic picture, maybe it's a flawed gem.

 I've spoke about sound qualities not musical qualities so I'll post again in a couple of weeks when I've had more listening time & see if the 2111 truly engages my emotions. Also, maybe it needs more than just a couple of days burn-in period to show it's complete best. * 
 

I agree completely with this assessment. I'm hearing significantly more bass energy with my DT880s when using the OPA2111, and at the same time the treble detail seems increased significantly as well, and the sibilance I had been hearing with the AD823 is gone. The soundstage is superb. I'm still unsure about the midrange however, as it seems about the same as with the OPA2134 and AD823, maybe slightly smoother but no too much different. I didn't think an opamp could make this much of a difference in tonal quality, but the OPA2111 has proved me wrong. Anybody with more experience want to try one out? Tangent?


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## morsel

It is easy to improve on the AD823 or OPA2132, but have any of you OPA2111 fans listened to the respective top of the line AD8620 or OPA627 (on BrownDog adapters)?


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## ADS

Quote:


 _Originally posted by morsel _
*It is easy to improve on the AD823 or OPA2132, but have any of you OPA2111 fans listened to the respective top of the line AD8620 or OPA627 (on BrownDog adapters)? * 
 

Nope, I've got two OPA637s sitting right next to me that I plan to install as soon as I get my BrownDog order from Tangent.


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## PinkFloyd

Quote:


 _Originally posted by morsel _
*It is easy to improve on the AD823 or OPA2132, but have any of you OPA2111 fans listened to the respective top of the line AD8620 or OPA627 (on BrownDog adapters)? * 
 

What "fans"?? this op amp hit me out of the blue and I gave it a try in the Chiarra amp, I originally started this thread asking if anyone had any experience of the 2111, the lack of replies forced me into trying it out for myself so I doubt there are many "fans" as yet. To my ears it sounds light years ahead of any other I've tried, after a good 2 weeks of 24/7 burn in, and I haven't experienced the lack of treble phenomenon. Thing is, I don't "plug and play"....... I tend to "plug and wait a day or two" and then listen. 

 Could be that you're expecting an op amp to "instantly" perform Nigel......... try leaving it powered up for a few days (preferably 200 hours - minimum) and then have a listen...... I think you'll be pleasantly surprised / shocked at what a difference adequate burn-in yields. You wouldn't expect to get the best out of a black Gate or Cerafine after "2" hours so why should an opamp be discounted after such a "brief" period in the circuit?

 Remember how the Chiarra sounded for the first few weeks and remember you've added a new component which will need a burn in too........ the 2107 may "initially" sound good but the old addage "good things come to he who waits" may well hold true with the 2111 

 Pity there isn't a burn in rack for op amps, it would make rolls a lot quicker and a lot more subjective.

 Pinkie


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## Nigel

Pinkie wrote :- To my ears it sounds light years ahead of any other I've tried, after a good 2 weeks of 24/7 burn in, and I haven't experienced the lack of treble phenomenon.>>

 Hi Mike, you think it sounds better than the 2107? Even one with shining pins


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## Nigel

Cheers Morsel,

 The AD-8620 I'd love to hear that! PinkFloyd, what do you reckon? Can you get your hands on a couple of these? Am I correct in thinking this would be a direct drop in replacement?

 With regard to the OPA 627, I know this one needs an adaptor, is this much different, musically speaking, to the OPA 2107?

 Pinkie, I'd love to hear a PPA, is this the top sounding unit? Wouldn't you love to compare the Chiara with one of these amps, Mike?

 After 48hrs using the 2111 I still find the treble dull but I'll give it a week to burn in like you suggest. I have to be honest & say that I can't hear major differences between the OPA 2132, 2604, & a unburnt in OPA 2107. However, the 2107 does sound similiar but marginally better, especially with my higher grade vinyl source. In fact it's the best opamp I've heard so far. The 2111 is a different kettle of fish however, or should that be different kettle of slew


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## PinkFloyd

Quote:


 _Originally posted by Nigel _
*Pinkie wrote :- To my ears it sounds light years ahead of any other I've tried, after a good 2 weeks of 24/7 burn in, and I haven't experienced the lack of treble phenomenon.>>

 Hi Mike, you think it sounds better than the 2107? Even one with shining pins  * 
 

Sounds "different" not better not worse.


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## wordsworth

Well I gave the 2111 a listen without any burning-in and I have to have I agree with Nigel, the treble frequency ends well before it does with the AD823. Personally i still prefer the AD823 but will give the 2111 a 2 day burn in. 

 Mike is it possible to connect the AD8620 or OPA627 with an adapter as I would like to try them out as its seems to be the choice of many on here?

 Wordsworth


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## wordsworth

I suppose to in part answer my own question, is there enough space for a browndog to fit in the chiara? Maybe some can tell on here as to whether it would fit or not. 






 The image is not the clearest as it is a croped version of PinkFloyd's chiara amp image.

 Wordsworth


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## PinkFloyd

Quote:


 _Originally posted by wordsworth _
*I suppose to in part answer my own question, is there enough space for a browndog to fit in the chiara? Maybe some can tell on here as to whether it would fit or not. 







 The image is not the clearest as it is a croped version of PinkFloyd's chiara amp image.

 Wordsworth * 
 

It will fit no problem Mark as the dip socket has the height to clear the nearby resistors comfortably. You're probably best buying the browndog direct and it will simply be a case of plugging it into your existing socket.

 Mike.

 PS: I've ordered a couple of AD8620's and will attempt making a contraption which will plug directly into the DIP8 socket


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## PinkFloyd

A slighty larger picture


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## wordsworth

Quote:


 I've ordered a couple of AD8620's and will attempt making a contraption which will plug directly into the DIP8 socket 
 

Let me know how you get on, I am keen to know your views on the op amp. 

 Wordsworth


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## ADS

Okay, I just plugged two OPA637s on a browndog adapter into my PIMETA to replace the OPA2111. The first thing I noticed was the HUGE soundstage, much larger than with the OPA2111. Treble is more prominent, and slightly more detailed with the OPA637s. Bass is more controlled, but equal in depth. The OPA637 really brings you back to the usual BB sound, which the OPA2111 departs from. I like the OPA637 a little bit more, but the OPA2111 comes _very_ close. Both are leagues ahead of the OPA2134, OPA2132, and AD823AN. The DT880s are extremely sensitive to changes in the amp, more so than I could have imagined. I'm probably going to have to upgrade to a PPA soon.


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## morsel

Try the AD8620 and let us know how you like it.


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## PinkFloyd

Quote:


 _Originally posted by morsel _
*Try the AD8620 and let us know how you like it. * 
 

I've ordered one from Tangent Morsel, is it really "that" good? Seems pretty reasonable at $12 for the chip and $4 for the adapter


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## blipblop

Why are more people not using the ad8620? I thought they were well-known to be the best. Is it the price, or the desire to experiment around? I ask because I bought the 8620 without batting an eye based on what I had thought. Now, maybe i should shop around with other chips to find one that suits me?


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## morsel

Personal preference, builder preference, and the belief that more expensive equals better are possible reasons.


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## PinkFloyd

Quote:


 _Originally posted by morsel _
*Personal preference, builder preference, and the belief that more expensive equals better are possible reasons. * 
 

The 8620 is "cheap" compared to a opa2107 / opa2111 In the UK a 2111 costs $32 compared to the AD8620 at a mere $12 ...... the OPA2107 clocks in at around $28 so if "expensive equals best" the 2111 / 2107 should be flavour of the month?

 I prefer to use my ears and in the Chiarra (this cannot be emphasised enough.. CHIARRA... not every application!) OPA2111 / OPA 2107 and AD823 / 712 are superb sounding op amps. I've ordered a few 8620's on Browndogs and can't wait to hear what all the fuss is about 

 In the meantime I'm listening to an AD OP271 and it's performing admirably...........

 AAAAAAARGH!!!! this op amp "rolling" can drive you crazy!!!!

 Pinkie.

 I "still" reckon the AD712 is the best op amp in the Chiarra but am afraid to mention it here in case it's slagged off as "old fashioned" or "Cheap" I don't give a damn......... the 712 rocks!


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## ppl

The OPA-2107 is and has been my fav for over 15 years in Dual Di-Fet BB OPA's I would avoid the OPA2111 its 2 Volts per uSec slew and 2 MHz GBP place it below the AD-712,OPA-2107 and not much better than the popular 4558. The AD-8620 IMHO is an upgrade to all of these althought I do have a fondness to the Warm non hard sounding AD-712 But you give up detail compaired to these newer devices.


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## Nigel

At the moment the OPA 2107 is the best sounding opamp I've heard in the Chiarra amp, obviously I've not heard as many as your goodself, ppl but would you agree that once you get to a certain standard sound quality differences tend to be minor.


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## PinkFloyd

Quote:


 _Originally posted by ppl _
*The OPA-2107 is and has been my fav for over 15 years in Dual Di-Fet BB OPA's I would avoid the OPA2111 its 2 Volts per uSec slew and 2 MHz GBP place it below the AD-712,OPA-2107 and not much better than the popular 4558. The AD-8620 IMHO is an upgrade to all of these althought I do have a fondness to the Warm non hard sounding AD-712 But you give up detail compaired to these newer devices. * 
 

Hi PPL,

 The Op amp utilisation in the Chiarra circuit would appear "theoretically" to have no effect whatsoever on sound quality but swapping op amps has a very pronounced effect on the sound and there is a "very" audible difference (see diagram) This amp seems to respond very noticeably to a change of chip and I wonder why this is the case........ can you throw any light on the matter after looking at the diagram??

 My favourite was always the AD823, closely followed by the AD712....... then again, the 2111 sounds valve like with undercurrents of guava floating on a honey base, the 2107 very nice with a hint of nettles dancing on a bed of strawberries with a strong sense of tarmac underpinning the bass, the 2227 could be described as "organic" you can really smell the soil with this op amp and can taste the earth....... 2132 is analytical though the infusion of camomile and aloe vera tame its microscopic view on the proceedings , 2604 warm ,moist and seductive, 2132 integrated, 2134 honky, 2228 organic though slightly GM Modified, LF353 harsh yet smooth, NE5532 a slight hint of water melon, AD OP271 mellow with a hint of raspberry ........... screw will somebody please hit me over the head with a hammer!!!!

 <screaming>


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## PeterR

Quote:


 _Originally posted by PinkFloyd _
 The Op amp utilisation in the Chiarra circuit would appear "theoretically" to have no effect whatsoever on sound quality 
 

Why? In a circuit like this (opamp + output stage in its feedback loop) I'd expect the opamp to be the single most important factor on the sound quality...


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## RichardH

I have the AD8620 on BrownDog in my Chiarra (as does London Luke). Very nice - mine's out on loan to a friend at the moment (spreading the Chiarra word), so can't currently do any opamp swaps for feelings on the differences. However, I liked it more than the 823, by a fair way.

 Be careful - the standard power supply puts out +-15v, and I believe (it was certainly suggested to me) that the AD8620 will only take +-12v.


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## PinkFloyd

Quote:


 _Originally posted by RichardH _
*I have the AD8620 on BrownDog in my Chiarra (as does London Luke). Very nice - mine's out on loan to a friend at the moment (spreading the Chiarra word), so can't currently do any opamp swaps for feelings on the differences. However, I liked it more than the 823, by a fair way.

 Be careful - the standard power supply puts out +-15v, and I believe (it was certainly suggested to me) that the AD8620 will only take +-12v. * 
 

Hi Richard,

 I'll measure between R1 "3k3" and 0V to see what voltage is being supplied to the opamp. I've looked at the 8620 data sheet and the voltage range is +/-5V to +/-13V. I hope the voltage supplied to the opamp "isn't" 15V 
	

	
	
		
		

		
		
	


	




 The absolute maximum "stress rating" of the 8620 is 27.3V so, even if it was receiving 15V it wouldn't melt but I don't want to sail that close to the wind!!!

 Mike.


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## wordsworth

well as I also bought a 8620 on a browndog from tangent I really hope that it can work in the chiara without having to make any major alterations. 

 Mike I will wait on your view as to whether it is safe or not to use the 8620 before I put it in the chiara.

 Wordsworth


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## RichardH

Changing the regulators from 7815/7915 to 7812/7912 on the power supply would do the job (and at little cost too), but I think Mike is keen to compare the ICs under identical circumstances - not that other ICs won't run happily at +-12v.


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## PeterR

Quote:


 _Originally posted by PinkFloyd _
 I'll measure between R1 "3k3" and 0V to see what voltage is being supplied to the opamp. 
 

That's the input, not the supply voltage. 
  Quote:


 I've looked at the 8620 data sheet and the voltage range is +/-5V to +/-13V. I hope the voltage supplied to the opamp "isn't" 15V 
	

	
	
		
		

		
			




 

According to the schematic it is...
  Quote:


 The absolute maximum "stress rating" of the 8620 is 27.3V so 
 

+/-15V means 30V supply voltage.


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## PinkFloyd

Quote:


 _Originally posted by PeterR _
*That's the input, not the supply voltage. 

 According to the schematic it is...

 +/-15V means 30V supply voltage. * 
 

So there will be no problems whatsoever in slotting the AD8620 into the circuit then Peter? Sorry but my brain is still suffering from over indulgence at New year!


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## 00940

Quote:


 ABSOLUTE MAXIMUM RATINGS*
 Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27.3 V

 Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those listed in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. 
 

So, no you can't simply drop the AD8620 into the Chiarra since it would get +/-15V, that is 30V from rail to rail.


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## PinkFloyd

Quote:


 _Originally posted by 00940 _
*So, no you can't simply drop the AD8620 into the Chiarra since it would get +/-15V, that is 30V from rail to rail. * 
 

LOL, and there was me with my "electrical" hat on thinking 15V is 15V forgetting the + / - making up 30V........ told you I had too much to drink over the new year!

 Well........... that's sailing VERY close to the wind so it looks like the AD8620's will be useless in the Chiarra "unless" the voltage supplied to the opamp measures + / - 13v or under.

 Does Tangent do refunds? 
	

	
	
		
		

		
		
	


	




 Pinkie.


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## 00940

can't you just drop a pair of LM7812/7912 regulators instead of the 7815/7915 currently in ? The heatsinks look big enough to dissipate 3 more volts. Pinout is identical.

 edit : richard beats me on this


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## PinkFloyd

Quote:


 _Originally posted by 00940 _
*can't you just drop a pair of LM7812/7912 regulators instead of the 7815/7915 currently in ? The heatsinks look big enough to dissipate 3 more volts. Pinout is identical.

 edit : richard beats me on this 
	

	
	
		
		

		
		
	


	


* 
 

Yep, I could do that but then "is" it worth it for an amp I am already really happy with? I was stupid to not check the voltage specs of the AD8620 before ordering 2 of them and I think I would rather just keep the PSU at the 15V the designer specified and say goodbye to the 8620's and just listen to the amp with the OPA 2107 which is sounding great.

 It's tempting to start replacing every component in the design and modifying it beyond recognition but to what end? The amp sounds superb in its natural form and I would hate to over egg my pudding and transform it into some kind of mutant device that is far removed from the original. The addition of a couple of cerafines and OPA2107 sounds good to me 

 If the 8620 could have simply been dropped in then, fair enough, but I'm not faffing about with 7812/7912 regulators just to accommodate this opamp. I doubt the 8620 would bring about an earth shattering "improvement" anyway? Maybe a subtle difference but certainly not night and day?

 Anyways, time to listen to the music instead of listening to the components


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## morsel

Ouch, sorry I suggested the AD8620. ±12V is the maximum safe supply for this opamp.


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## PinkFloyd

Quote:


 _Originally posted by morsel _
*Ouch, sorry I suggested the AD8620. ±12V is the maximum safe supply for this opamp. * 
 

That's ok 
	

	
	
		
		

		
		
	


	




 You weren't to know the Chiarra was 15V Morsel. Thank God RichardH pointed it out or I would have been smelling melted opamp emitting from my headphone sockets 
	

	
	
		
		

		
		
	


	




 If anyone wants to swap 2 x 8620 on browndogs for 1 x 627 on browndog let me know.

 Pinkie.


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## 00940

Well, even if you changed your mind, it wouldn't be as easy as i initially thought. I certainly wouldn't change the +/- 15V needed for the discrete buffer.

 You would have choice between two solutions : a complete different power line taken before the lm7815/7915 currently in, regulated to +/- 12v and then brought right to the ad8620 pins. Heavy work. Or an hack solutions, bringing down the 15V lines to 12v. But a 3V margin is a bit low for regulation and could lead to more losses than gains.


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## PinkFloyd

Quote:


 _Originally posted by 00940 _
*Well, even if you changed your mind, it wouldn't be as easy as i initially thought. I certainly wouldn't change the +/- 15V needed for the discrete buffer.

 You would have choice between two solutions : a complete different power line taken before the lm7815/7915 currently in, regulated to +/- 12v and then brought right to the ad8620 pins. Heavy work. Or an hack solutions, bringing down the 15V lines to 12v. But a 3V margin is a bit low for regulation and could lead to more losses than gains. * 
 

Exactly!! Thanks for that 00940, I'm glad you said that and not me 
	

	
	
		
		

		
		
	


	




 Thanks!!!!!


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## blipblop

So, any comparisons. now that time has passed, on AD8620/8610 versus the OPA637/627 opamps?


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## RichardH

The only "easy" way to do it would be to make use of the spare sections on the Andante - it has a board capable of providing up to 5 rails - 3 pos and 2 neg IIRC - you could add the components to give the +-12v. But Pinky, I think you're right - it's very easy to start going round and round, and if you're happy as it is, then just sit back and listen! I must say though, that I will (at some point) be trying alternative power supply regulation in the next few months.


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## PinkFloyd

Quote:


 _Originally posted by RichardH _
*The only "easy" way to do it would be to make use of the spare sections on the Andante - it has a board capable of providing up to 5 rails - 3 pos and 2 neg IIRC - you could add the components to give the +-12v. But Pinky, I think you're right - it's very easy to start going round and round, and if you're happy as it is, then just sit back and listen! I must say though, that I will (at some point) be trying alternative power supply regulation in the next few months. * 
 


 Problem solved! I've got a couple of OPA627BP's (the mil-spec version of the 627AP) and am now awaiting a dual single Dip8 adapter from Tangent 
	

	
	
		
		

		
		
	


	




 These should sound PDG!!

 Pinkie.


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## Budgie

For what it's worth, I tried the 8610/8620 as the opamp in my CDP and found that not only is it the nicest sounding opamp I have tried, yet, I also found out my chips could survive +/- 15 volt rails for about an hour or so, until I took a second look at the spec sheet.
	

	
	
		
		

		
			





 I would not, however, recommend any one else try this "exsperiment" (screwup). 
	

	
	
		
		

		
		
	


	




 I now have OPA627/637 in there. Does not sound as good, but not bad, and they will take the rail voltages. I am still searching for the best opamp for my application, however. The surprise for me was that the 5534 actually sound pretty damn good when biased class A.


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## PinkFloyd

Quote:


 _Originally posted by Budgie _
*For what it's worth, I tried the 8610/8620 as the opamp in my CDP and found that not only is it the nicest sounding opamp I have tried, yet, I also found out my chips could survive +/- 15 volt rails for about an hour or so, until I took a second look at the spec sheet.
	

	
	
		
		

		
		
	


	




 I would not, however, recommend any one else try this "exsperiment" (screwup). 
	

	
	
		
		

		
		
	


	




 I now have OPA627/637 in there. Does not sound as good, but not bad, and they will take the rail voltages. I am still searching for the best opamp for my application, however. The surprise for me was that the 5534 actually sound pretty damn good when biased class A. * 
 

Doesn't always make sense Budgie. I still rate the AD823 in the Chiarra but "market forces/ peer pressure" dictate I should listen to browndogs / browncats / brownrats...............

 ce sera sera......... ces't la vie

 Pinkie.

 It's all Bollox........ if it sounds good you're either pissed or stoned


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## london luke

Hi Richard

 What do you reccon... try one of these in my amp ??( ladies and gents.. I havent a clue whats in my amp...!!!! I just go with the flow)

 Again the Chiarra is making a name for its self.

 Luke


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## RichardH

Luke, you have the AD8620 in your amp. I may have an AD823 spare if you want to try that for interest - I'dd agree with Pinky that it's certainly a good 'un, but I do prefer the one you have in there at the mo'.


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## moeburn

Sorry to resurrect an old thread, but I have to say, the 2111 is far to amazing to not be tried. 

 I'm using an A47/Cmoy variant, four opamps, and one 9v battery so it will fit in an altoids case. I replaced the two 2227 opamps with two 2111 opamps, the difference is noticeable. Treble is no longer piercing, before it sounded like an icepick in my skull, now it sounds warmer, but not absent. I don't know why they're rated at 10v minimum, they sound just fine on a dying 9v battery.


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## diredesire

Quote:


  Originally Posted by *moeburn* 
_Sorry to resurrect an old thread, but I have to say, the 2111 is far to amazing to not be tried. 

 I'm using an A47/Cmoy variant, four opamps, and one 9v battery so it will fit in an altoids case. I replaced the two 2227 opamps with two 2111 opamps, the difference is noticeable. Treble is no longer piercing, before it sounded like an icepick in my skull, now it sounds warmer, but not absent. I don't know why they're rated at 10v minimum, they sound just fine on a dying 9v battery._

 

Gotta say, my interest is piqued... Can anyone compare (in depth) these chips to OPA 627/637 & 2132/2227? (I know there are a few comparisons to the latter in the thread, but looking for some more input)... Maybe PinkFloyd can comment on this now that he is older and wiser?


----------



## IEATTEFLON

I tried them in a cmoy circuit. IMO it sounded too polite and bland. I still prefer the good old opa2132 with a nice power section. In my tests the OPA627 is also on the bland and mushy side considering how much it costs.


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## moeburn

Since I'm on the "sample" budget, I didn't get any 627s, but I have that fancy dual AD chip that everyone's been raving about on the way. Gonna solder it to a DIP adapter and compare. 

 I should probably find out what this 2111 thinks of 18v too...


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## AsuAmo76

Ad8620 is great by all accounts - both specs and reviews. However...

 I am doing new amp now (opamp in 1st stage feeding irf510 with some tweakings in current sinks). When I started rolling up opamps, it's became the shoking experience. 

 ad8620 - very and I mean VERRRRRY airy. Sort of cardas senns replacement cable. Very detailed, but definitely on the bright side. Overall wasn't happy, not good for long listening. 

 ad823 - pleasant. Accurate. Nothing special, but they sounded way more quiet compare to all others. Assumed overload and ruled them out on this design stage. 

 LF412 - fast and clear. Nothing spectacular, but still detailed and better than 8620 (at least for this schematic, sr-325 and my ears)

 LF442 - clear winner. You will lough at their specs http://www.national.com/ds/LF/LF442.pdf , but they produced very musical sound, grainy (bipolars?), dark and inspairing. You will want to enjoy music rather than evaluating your gears. Krall, Piaf, Tchaikovsky and more ...
 --------------------------
 By the way, did somenone experience this too much "air" sound? Is it a sort of oscillation on very high frequences? ad8620 can be critical to assembley, wires length and parasite capacities.
 -------------------------------
 My immediate response - why do I need all this??? Move to all discrete schematics, asap.


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