AnthonyAsh said:
I know that, but that's a very low biasing, and not at all optimized for the OPA627.
For a +/-15v psu, try 1.8k, for +/-18v, 2k.
I suppose you have missed this:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=38984&highlight=
I will try it,it actually very easy to implement and listen,then spend time in discussions🙂
BTW ,I've got good results with 10uf Black Gape P-K in decoupling+0,1 polypropylene+wima 2200pf.They must be connected directly to pins,i put BG on back side,and polypropilene on chip botton. And I've got some improvement of sound.
I heard very good is BG N 0,1 uF,will try it soon.
BTW ,I've got good results with 10uf Black Gape P-K in decoupling+0,1 polypropylene+wima 2200pf.They must be connected directly to pins,i put BG on back side,and polypropilene on chip botton. And I've got some improvement of sound.
I heard very good is BG N 0,1 uF,will try it soon.
I used AD825 in my RCD990 mod. I put them in I/V , filter , output (coupled with Mundorf Supreme ) . Sound is top rate by every point of view. I did not try 627 , but i don´t think it will do better than much faster AD825(much shorter settling time , faster rise time...).
OPA2604 can be very good performer in line stage preamp section.
The very important thing is the level of negativ feedback used with this and other OP-s (if we dont count the quality of PS). I discovered that NFB resistors ratio must be close to 1:10 , 1K to ground /10K from output to invert input. Sound was very transparent fast and neutral.
I dont think that OP-s distorzion can afect sound that much. I mean we are talking abuot 0.0003% for 1KHz step.
It is nothing compared to some tube or discrete designs which are musical, and neutral .
I think the quality of perifer components and PS around OP ,are of bigger imprtance than the type of OP(I am talking of good ,and fast OP-s) .
OPA2604 can be very good performer in line stage preamp section.
The very important thing is the level of negativ feedback used with this and other OP-s (if we dont count the quality of PS). I discovered that NFB resistors ratio must be close to 1:10 , 1K to ground /10K from output to invert input. Sound was very transparent fast and neutral.
I dont think that OP-s distorzion can afect sound that much. I mean we are talking abuot 0.0003% for 1KHz step.
It is nothing compared to some tube or discrete designs which are musical, and neutral .
I think the quality of perifer components and PS around OP ,are of bigger imprtance than the type of OP(I am talking of good ,and fast OP-s) .
Gasho said:
I agree with you, it sounds better on a line preamp than inside a CDP (either for I/V or for buffering).
This thread started because of mods to a CDP.
I always find the OPA2604 a little "rude", coarse sounding here, specially in the midband and treble.
The OPA2132 is superior in either role, and the LM6172 is (most of the times) even better.
What I haven't tried was feeding the OPA2604 with +/-24V.
carlosfm Aug '04 said:
carlosfm Oct '04 said:
Carlos has the OPA 637 now beaten the LM6172 for you?
IanAS said:
I was just talking about double op-amps.
And notice: nothing's universal.
The OPA627/37 is better than the LM6172, but it's not a night and day improvement.
Also, an op-amp can't be the best everywhere.
The 627/37 are amongst the best, but I have had better results with the AD847 in a particular application.
IanAS said:
I have recently used the THS4062 (the same, but double) on the headphone output of a cdp and the results were very good.
But I don't have much experience with it on other circuits, so I can't comment much more.
carlosfm said:
I find the OPA2604 sounds rather screechy. It sometimes sounds as if the musicians aren't quite playing in proper time. It's among the worst of the many op-amps I've tried, JRCs included.😉
I've have an AD8620BR (I'll be useing it with an SOIC-to-DIP adaptor) and a OPA2277P on order, they should arrive on Monday. I'll post my impressions of these chips in a few days. FWIW the OPA2277s are the stock op-amps in the RCD-1072.
The OPA2277 is now my favorite BB chip, far better then the OPA2132! I'm very pleased with it, it has a very lovely top-end. It doesn't seem quite as fussy about PS bypassing as the other BBs I've tried; the bloated bass thing doesn't happen, it just gets a little bit fuzzy in the mid-range. I do have a minor gripe; it lacks a little bit of dynamic impact or 'bass snap' but other then that it's excellent. If your a BB fan you owe it to yourself to try it.🙂
I'm going to order a couple of Linear Technology op-amps; the LT1113 and the LT1124. Does anyone have any experience with these? The LT1115, a single, looks very nice, it has ultra-low noise, the first page of the datasheet shows a MC/MC phono RIAA circuit as typical application! That's my kind of company.😀
http://rocky.digikey.com/scripts/ProductInfo.dll?Site=CA&V=161&M=LT1115CN8
http://rocky.digikey.com/scripts/ProductInfo.dll?Site=CA&V=161&M=LT1115CN8
This is neverending searching with dubious results, based on subjective opinions. Can someone define, what is " realy good " opamp ? But without these " hifimagazine's newspeak ", please. 😎 .
Hans L said:
Thanks. 🙂. I will get to it soon; first I have to adjust my regulators for lower voltage, the AD8620 has a max of +-13V.
Gaucho said:
The 8620 is an interesting chip, easily the most detailed of all the op-amps I've tried. It's good but not without fault; it lacks some dynamics and the top-end is a touch dry. In spite of it's short coming the mid-range refinement/detail retrieval is quite special, it in an not-so-abstract sort of way it turns the sound of your box speakers into panels.
The Linear Technology chips I ordered last night arrived today, all the way from Minnesota! Only 8 bucks shipping, Yeah Digi-Key! My initial impressions of the LT1113 are very very good! Even cold with no break in it betters the OPA2132! It has fantastic dynamnics and is tonally very well balanced. The trebble althought very good is not quite in the same league as the AD823 and the OPA2277 but perhaps with some burn in...
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