The coveted OPA637 in Pimeta...
Dec 13, 2007 at 3:43 PM Thread Starter Post #1 of 16

slowpogo

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I just got my two OPA637's in the mail. I put them in my Pimeta, and wow, they do sound good. I can hear the ambient space of the room/hall so much better than any other opamp, and the bass is full, deep and tight. Soundstage is respectable, detail is lively and musical...verrry nice.

I'm having trouble finding a good match for the ground channel, though. The AD744 sounds OK, but not very exciting. The AD829 seems too intense; things get super thin and punchy. I tried the LMH6654 in ground, and it sounds good but there is a hiss when I turn the amp on, which slowly dies down but is still very audible.

I know the OPA627 is the traditional match for the ground channel, but what else works well? I'm thinking of trying the AD825 and AD8065 next.
 
Dec 13, 2007 at 4:23 PM Post #2 of 16

Bjornboy81

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what type of headphones are you using? I'm finding the AD8620 (L&R) and AD8610 (G) are a bit harsh with grados and I wanted to try something else.
 
Dec 13, 2007 at 5:53 PM Post #4 of 16

majkel

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As I remember, Audio Technica's tend to be bright, so you can try AD845 in the ground channel but actually there is no clear answer. You have to try as many as possible and find the one. OPA637 is very good for DT880's but too polite for Senns. AD845 is dark and tubey, AD811 is on the opposite side. AD825 is one of my favourites, adding meat to low bass, broadening the soundstage and adding nice timbre to the midrange. AD8065 is darker, with narrower soundstage, and a bit hollow lower midrange. Its trebles are are a bit too pronounced for me.
OPA211 is also very interesting, clean, with big soundstage and no aggression. And so on, and so on...
 
Dec 14, 2007 at 10:31 AM Post #5 of 16

NelsonVandal

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Quote:

Originally Posted by majkel /img/forum/go_quote.gif
OPA211 is also very interesting, clean, with big soundstage and no aggression.


Majkel, so you've got your OPA211's. Can't you please review it and compare it to some other opamps. Do you still prefer AD825? How is it compared to LM4562? I'm awaiting AD797, and I'm thinking of trying them both unbuffered and in the LISAIII-clone. Like you've said, AD744 is a bit anemic, and has that typical "Analog-harshness".
 
Dec 14, 2007 at 11:29 AM Post #6 of 16

majkel

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Well, OPA211 is kind of weird to me. Mostly it resembles OPA604 but sounds more transparent. While being more than good, it doesn't deliver enough fun IMHO. There is big soundstage, neutral to dark presentation, slightly too distant and small instruments. If it sounded a bit more harsh, meaning better audibility of instrument texture, then it would be perfect. AD825 is less transparent but what it makes to the HD595 (already sold, BTW) is like a horse and a carriage. Same for the HD600's. AD825 is less transparent but more fun, OPA211 more transparent but the remaining imperfection is of a worse kind IMHO. The closest comptetitor for the OPA211 is ADA4841-1 but this op-amp is way better. Maybe it's the best one I've heard but it's 12V max. total supply only, so not to be used everywhere. Too bad.
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Dec 14, 2007 at 12:46 PM Post #7 of 16

Epicurean

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I like the OPA637 a lot and has been one of my favorite opamps for a while now. I recently tried some AD825s and while they are very nice in their own way, I still like the OPA637 better and think it sounds more life-like. And note that I'm using HD650s and HD600s!

My favorite opamp right now though is the OPA2107, it is INSANE! I've had them for almost a year already and thought they were nice in my Zhaolu before I got the Zapfilter. Then in a moment of boredom I made a PINT-like thing using my 2 OPA2107s and it totally rocks! The sound is very much like the OPA627/37 but with more punch and a thunderous bass without getting annoying. The funny thing is the PINT doesn't even have any buffers after the opamp and it still beats my PPA right now
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The senns needing a lot of power to sound good has got to be one of the biggest myths on this forum.
 
Dec 14, 2007 at 7:16 PM Post #8 of 16

slowpogo

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Quote:

Originally Posted by Shopper /img/forum/go_quote.gif
I have read that the LT1363/4 (which is one of my favorites) would sound better than the AD825 (which I've not heard). The LT1360/1 is also very good.


Do you mean the LT1363 is a better match with the OPA637, or just better in general?
 
Dec 15, 2007 at 12:33 AM Post #9 of 16

majkel

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Four year old thread. Since that time many new op-amps have appeared like i.e. OPA1632, and if you know how to wire it unbalanced, that's it. I have a hard time do decide which one is better: ADA4841-1 or OPA1632? The former is very linear, and the biggest non-linearity is around 4uV in the 1-4V amplitude region. So this means ADA4841-1 is linear like hell. OPA1632 is one of very few op-amps you can find out something about its IM distortions. This is where most op-amps and circuits with NFB loop suck, so nobody is going to share these data. And actually I could say that compared to ADA4841-1 or OPA1632 all low output current op-amps suck, more or less. You can like some because of this or that sonic feature but they suck in terms of transparency and lack of ingerention into timbre, soundstage, PRAT, etc. Probably no electronic circuits remain transparent but many op-amps are obviously changing the sound, cutting off some sonic content.
Regarding LT's, I tried 3 types which I don't remember and they did not impress me at all. Secondly, Linear often stops sending samples to Poland which doesn't make it easy to try their products, so I don't care either.
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I know an amplifier designer who claims old LT1028 is still better than LT1364, so if I feel in need of discovering another op-amp, maybe I'll check those out.
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Dec 15, 2007 at 11:47 AM Post #10 of 16

NelsonVandal

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Majkel, or anyone, when you think of it, don't you think there's a bipolar and a jfet sound? Think of LM4562, LM6171, AD8058, ADA4899, AD8045, AD829, LMH6642, LMH6654 etc and compare the sound to OPA2134, OPA2107, AD823, AD744, AD8599, AD825, AD8066 etc. I find the jfet's to be grainy, warm, add contours, add "body" even in the high frequencies. Maybe they're more musical. Bipolars are more free floating, clean, airy, vague, and maybe more neutral. AD8397 is bipolar but is grainy and add contours, it doesn't fit the description.

What about ADA4841-1, isn't there an offset problem? Using Tangent's calculator, there should be 127 mV DC-offset at a gain (1k/4k resistors) of 5 using a 10k pot and a 100k from input to ground.
 
Dec 15, 2007 at 1:20 PM Post #11 of 16

majkel

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NelsonVandal - I haven't found anything like FET or bipolar sound. However, I think bipolars sound cleaner. Even regarded OPA637 isn't perfectly clean.

Shopper - I'm a Linear noob. I've read they are sending samples again so I can try. Regarding AD825 - wrong guess. It does not add sibilants but some more color. Imagine a TV set, you suggested it bumped the sharpness, I claim it turn up color intensity a bit, but you need to listen to this chip. Disregarding LT's which I merely know, there is nothing like AD825. I'm not saying it's the best and only, but it's very interesting, indeed.
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I don't like LM6172 either - too cold, thin, technical...
 
Dec 15, 2007 at 3:54 PM Post #13 of 16

majkel

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Quote:

Originally Posted by Shopper /img/forum/go_quote.gif
Which other opamp with colorful tonality would you recommend me for the output stage of a DAC?


AD8022, it's dual and no single version. And is musical like... music.
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Watch out its high input currents, but if there are other opamps/buffers before it, you can try. Directly from the DAC chip - I don't recommend. Better will be FET input here.

OPA211 is single, OPA2211 is dual but I haven't tried the dual version.
 
Nov 17, 2008 at 4:04 AM Post #14 of 16

luvdunhill

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Quote:

Originally Posted by NelsonVandal /img/forum/go_quote.gif
Majkel, or anyone, when you think of it, don't you think there's a bipolar and a jfet sound? Think of LM4562, LM6171, AD8058, ADA4899, AD8045, AD829, LMH6642, LMH6654 etc and compare the sound to OPA2134, OPA2107, AD823, AD744, AD8599, AD825, AD8066 etc. I find the jfet's to be grainy, warm, add contours, add "body" even in the high frequencies. Maybe they're more musical. Bipolars are more free floating, clean, airy, vague, and maybe more neutral. AD8397 is bipolar but is grainy and add contours, it doesn't fit the description.

What about ADA4841-1, isn't there an offset problem? Using Tangent's calculator, there should be 127 mV DC-offset at a gain (1k/4k resistors) of 5 using a 10k pot and a 100k from input to ground.



NelsonVandal: what do you think of the LMH6642? Listening to it right now and sounds very good for a low power. Probably best I've heard <= 3mA Iq. What do others think?
 

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