govibe v5s which opamps do you use?
May 6, 2007 at 3:25 PM Thread Starter Post #1 of 24

theBigD

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i want to get govibe v5s. just looking for different op amp suggestions. really want to know if it is worth upgrading to ad8610/8620 from stock op amp. using with ety er6c and akg 701 and grado sr 125. thanx for your time and recommendations.
 
May 6, 2007 at 7:24 PM Post #2 of 24

jenhwa

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definitely yes
 
May 6, 2007 at 8:24 PM Post #3 of 24

chris_ah1

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How about putting in a LM4562 in there if it will work with the voltages?
Need to put it on a SOIC adapter though.

Some like OPA2227 too.

Which is stock? AD8620 are considered to be the best by many though.
 
May 7, 2007 at 2:09 PM Post #4 of 24

DDF

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I've compared the 9620/8610 in my V5S to the stock ICs in my V5 and I'm still on the fence.

The 8620/10 are much clearer, have pin point imaging, great seperation and much more detail. But (you knew this was coming) I find they increase the sibilance and almost sound more like hyped detail (odd order distortion).

This is with an MSB Link DAC, into DT770s (old pair)

I have to reserve judgement. Is it that the stock ICs provide synergy with my cans but the 8620/10 are more accurate? Or is it that the 8610/20 are actually too aggressive? I don't know.

I know its not the dac, as I've lived with for 10 years over many different systems and high end speakers.

That being said, if your source is a typical DAP or budget CD player with a bit of a muddy sound, I can see the 8620/10s adding a missing sparkle, and the stock ICs adding too much vagueness and warmth.
 
May 7, 2007 at 2:29 PM Post #5 of 24

theBigD

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DDF, thanx for your concise report on 8610/8620, that was what i wanted to hear. i am listening to mp3 on computer with x-fi with akg 701 and etymotic er4p (now) er6s soon and grado sr 125. i think i am going to order op the stock go vibe along with 8610/20 for comparison. i am a detail freak, so it will be interesting to experiment a bit. does anyone know of any opamp compatable with govibe 5 besides 8610/20 that is excellent for midrange and treble extension, maybe a bit more analytical sounding than 10/20?
 
May 7, 2007 at 3:53 PM Post #6 of 24

Dexdexter

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Quote:

Originally Posted by theBigD /img/forum/go_quote.gif
does anyone know of any opamp compatable with govibe 5 besides 8610/20 that is excellent for midrange and treble extension, maybe a bit more analytical sounding than 10/20?


The AD8620/8610 is the best I've heard in my V5S, but the LM4562 runs it very close indeed; either are much better than the stock LM6172/6171.

Quote:

Originally Posted by chris_ah1 /img/forum/go_quote.gif
How about putting in a LM4562 in there if it will work with the voltages?
Need to put it on a SOIC adapter though.



The LM4562 is available in a DIP-8 mount also, so there's no need for a SOIC adapter.
smily_headphones1.gif


So you could order an LM4562 and just swap it out for the LM6172, leaving the LM6171 in the ground socket, if you don't want to spend the extra cash for the AD8620/8610.
 
May 7, 2007 at 6:43 PM Post #7 of 24

DDF

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>The AD8620/8610 is the best I've heard in my V5S, but the LM4562 runs it very close indeed; either are much better than the stock LM6172/6171.


Hi, I'm curious, what are you using for a source in this comparison?
 
May 7, 2007 at 7:39 PM Post #9 of 24

atx

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I put opa627s in the v5s. the battery drains like a hummer but I like it a lot. I use it with my triport IE's since i'm a soundstage freak and this gives the best soundstage.
icon10.gif
 
May 7, 2007 at 8:10 PM Post #10 of 24

DDF

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Quote:

Originally Posted by Dexdexter /img/forum/go_quote.gif
Sony CD Walkman D-EJ2000 & iPod 5G

The AD8620 remains superior overall, it's just that in my set-up the LM4562 performs closer to it than it does the LM6172.



Thanks, that makes sense. The 8620 sounds better than the 6172 with my Sony walkman also, and with my iRiver DAP, but not with the higher end MSB link dac (different, not clearly better).

I think its important when rating amps that the system be considered (and mentioned) as so much of this is synergy.

Reading the posts all these months I see a clear trend for preferring certain ICs (e.g. 2134s) with daps and PCDPs, but not with Pcs or stand alone dacs.


I'm thinking of changing the msb's o/ps to OPA627s (bought a bunch off eddy), I'm thinking that might let the 8620 really strut its stuff given it has a less clinical sound than the motorolas in there.
 
May 7, 2007 at 8:35 PM Post #11 of 24

Filburt

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I would ask for some other configuration from what Norm offers by default, personally. I don't think the AD8620 is really suitable for driving headphones both from its specifications and from its sound. The damping ratio isn't that great nor is the recovery, and it's not designed to drive low impedance loads. So, overall, you're likely to get substantial distortion. The topology of the PINT and related designs (like the GV5/6) was designed with an op-amp like the AD8397 in mind, because that chip is designed to drive low impedance loads and has excellent damping/recovery, reactive load driving characteristics; e.g. far superior drive characteristics compared to something like the AD8620. Op-amps like the AD8610/20 and OPA627, if you must use them, really shouldn't be used to drive headphones without a buffer. The AD8397 does well because it has a buffer stage integrated into it.

Maybe try AD8397 with ADA4899-1 on 'Ground' channel *shrug*.
 
May 8, 2007 at 1:09 AM Post #12 of 24

DDF

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Quote:

Originally Posted by Filburt /img/forum/go_quote.gif
I would ask for some other configuration from what Norm offers by default, personally. I don't think the AD8620 is really suitable for driving headphones both from its specifications and from its sound. The damping ratio isn't that great nor is the recovery, and it's not designed to drive low impedance loads. So, overall, you're likely to get substantial distortion. The topology of the PINT and related designs (like the GV5/6) was designed with an op-amp like the AD8397 in mind, because that chip is designed to drive low impedance loads and has excellent damping/recovery, reactive load driving characteristics; e.g. far superior drive characteristics compared to something like the AD8620. Op-amps like the AD8610/20 and OPA627, if you must use them, really shouldn't be used to drive headphones without a buffer. The AD8397 does well because it has a buffer stage integrated into it.

Maybe try AD8397 with ADA4899-1 on 'Ground' channel *shrug*.



Must be talking about a different part? Pulling down the 8620 spec sheet from the AD site:

The spec sheet rates it for 30ma with 2V o/p, which is a min 67 ohm load. Unfortunately no distortion spec at this load, but it looks more than fine for HD (it'll push 60 mA into a short).

Damping factor is more than fine. At gains as high as ten its under an ohm to 100 kHz, and at the gain of the V5s (2) its under an ohm out to 500 kHz.

The large signal response is unbelieveably clean from the spec sheet, and the small signal overshoot blows away the 6121, so its recovery also looks to be exemplary.

All in all, it specs out great for headphones.

But these are just specs. I notice the amp gets warm, which is strange. Mine may be oscillating (just a guess), which would explain some of the reservations I hear, and explain the heat.
 
May 8, 2007 at 2:10 AM Post #13 of 24

Filburt

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Quote:

Originally Posted by DDF /img/forum/go_quote.gif
Must be talking about a different part? Pulling down the 8620 spec sheet from the AD site:

The spec sheet rates it for 30ma with 2V o/p, which is a min 67 ohm load. Unfortunately no distortion spec at this load, but it looks more than fine for HD (it'll push 60 mA into a short).

Damping factor is more than fine. At gains as high as ten its under an ohm to 100 kHz, and at the gain of the V5s (2) its under an ohm out to 500 kHz.

The large signal response is unbelieveably clean from the spec sheet, and the small signal overshoot blows away the 6121, so its recovery also looks to be exemplary.

All in all, it specs out great for headphones.

But these are just specs. I notice the amp gets warm, which is strange. Mine may be oscillating (just a guess), which would explain some of the reservations I hear, and explain the heat.



Hmm, I remembered a different practical result from the 8620 when I tested that, but maybe I am thinking of a different part. I don't think the impedance comes out so low when trying to drive something like headphones (especially since the load is variable, which brings into account the overall stability of the system), but maybe I'm wrong on that. I wouldn't use the 6171/2 as the benchmark, though, as it suffers in several areas in terms of performance. I can't find anything in the SSO specs that gives sufficient data to extrapolate recovery on headphones; my experience with the chip gave the impression that it wasn't that stellar at low impedance, but it could be something else was responsible for this.

Maybe I was thinking of a different part for some of the criticisms, although I didn't think so...odd. I've tried to use the 8610 several times in audio, though, and have never gotten particularly exemplary results, either in listening tests or running it on some test equipment. Subjectively, I think it sounds inferior to much of AD's suitable offerings, but I guess it isn't the worst I've ever heard, although it was one of the worst I'd tested in the PINT. In terms of measured performance, I didn't manage to get out of it what I expected by the hype of its datasheet, although I think some of the criticisms of the 627 that it points out are fair, and it did perform better than something like the 6172. After using about 50 or 60 op-amps now in various duties, I still don't think the 8610/20 is really a good choice, especially for this kind of application. I didn't get around to testing it but maybe its problem is something like TIMD or something related rather than simple HD problems...or something else that isn't occurring to me at the moment. Unfortunately, AD doesn't provide a plot from DC of the open loop response, though the very high gain at DC and relatively low slew rate suggests that it's probably not very wide. That isn't always fatal but it does seem to be detrimental to performance with some designs. The 8610 seems to perform considerably better with a buffer at its output, which is one thing that made me look to recovery amongst other things, although still not what I'd consider a high performance choice for audio.
 
May 8, 2007 at 2:44 AM Post #14 of 24

DDF

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The small package makes me a bit nervous about driving dynamics into lower impedance loads, especially with no heat sink. But I've been using it with 600 ohm cans, so its not being stressed.

I really thought what I heard was high order THD, it sounded so familiar as brightness in the sibilance and an edge to breathy vocals. There's a common trait in some metal cone speakers: high order THD providing hyped sense of detail, and I thought thats what I heard here. But it also could be that something went south on the Link DAC, I'll check that too.

I picked up an ESI Julia, so I'll put them on the PC "bench" some time next week. If I get time at work I'll stick it on an analog scope and look for any Rf ringing.

Its a wierd part, in some ways it sounds so good, but the over-all presentation is a bit too high on the contrast control. Oddly enough, it seemed to be the Ic of choice in the GV5 thread.
 
May 8, 2007 at 3:12 AM Post #15 of 24

Filburt

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Quote:

Originally Posted by DDF /img/forum/go_quote.gif
The small package makes me a bit nervous about driving dynamics into lower impedance loads, especially with no heat sink. But I've been using it with 600 ohm cans, so its not being stressed.

I really thought what I heard was high order THD, it sounded so familiar as brightness in the sibilance and an edge to breathy vocals. There's a common trait in some metal cone speakers: high order THD providing hyped sense of detail, and I thought thats what I heard here. But it also could be that something went south on the Link DAC, I'll check that too.

I picked up an ESI Julia, so I'll put them on the PC "bench" some time next week. If I get time at work I'll stick it on an analog scope and look for any Rf ringing.

Its a wierd part, in some ways it sounds so good, but the over-all presentation is a bit too high on the contrast control. Oddly enough, it seemed to be the Ic of choice in the GV5 thread.



Higher order HD is one thing I've heard as well as what I witnessed in some cases when trying to test the chips; in fact, I was going to include that in an edit of my post but I guess I closed the window before applying. However, I think maybe TIMD or just straight IMD is probably in play as well. I really think the AD8397 is much better suited in something like this, personally. The AD4899-1 is a chip I haven't tested yet, but it seems to have a buffer stage on it as well, like the 8397, and has wide open loop response (relatively speaking) which I tend to favour. The 8620 probably does sound considerably less muddy than the 6172, which doesn't recover well, but I find that it's not a good performer overall. AD makes several op-amps that work well with audio, so it's not like there aren't alternatives.
 

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