Ad8610 supplies
Peter,
Your results mirror those reported elsewhere, i.e. operating Ad8610 at +-15V gave a thin top-end. I am running mine at +-13V.
http://db.audioasylum.com/cgi/m.mpl?forum=tweaks&n=83275&highlight=15V,+8610&session=
Carlosfm,
I find the use of the Goudreau triplet very beneficial. Maybe your THS4062/1 was needing this. It certainly lowers the perceived noise floor for all op-amps.
Peter,
Your results mirror those reported elsewhere, i.e. operating Ad8610 at +-15V gave a thin top-end. I am running mine at +-13V.
http://db.audioasylum.com/cgi/m.mpl?forum=tweaks&n=83275&highlight=15V,+8610&session=
Carlosfm,
I find the use of the Goudreau triplet very beneficial. Maybe your THS4062/1 was needing this. It certainly lowers the perceived noise floor for all op-amps.
Finally , choosing an op amp depends on your taste
i'm not pleased with Burr Brown op amp presentation
I prefer the AD ( except AD8620 ) , particularly the 826
I 've spent my last two weeks testing op amps on a UCD180 buffer stage ( hypex module , classD)
the second choice was the 5532 in Philips version , which is an op amp with a beautiful distorsion spectrum ( this op amp is coming back , you can see it on the last Accuphase DP65 or last McIntosh preamps or DAC MDA1000 )
alain
i'm not pleased with Burr Brown op amp presentation
I prefer the AD ( except AD8620 ) , particularly the 826
I 've spent my last two weeks testing op amps on a UCD180 buffer stage ( hypex module , classD)
the second choice was the 5532 in Philips version , which is an op amp with a beautiful distorsion spectrum ( this op amp is coming back , you can see it on the last Accuphase DP65 or last McIntosh preamps or DAC MDA1000 )
alain
I've heard very bad sounds from Burr-Brown OPAs whith less than ideal PSU bypass and layout.
On the same circuit the NE5532 wins hands down to the OPA2604 and OPA2132.
When I make it my way, the OPAs (and others) win.
So, I must say that op-amps are not just drop-in replacements as they should be.
Some modern op-amps demand more attention, and then they deliver.
This is my experience, take it or leave it, everyone.
On the same circuit the NE5532 wins hands down to the OPA2604 and OPA2132.
When I make it my way, the OPAs (and others) win.
So, I must say that op-amps are not just drop-in replacements as they should be.
Some modern op-amps demand more attention, and then they deliver.
This is my experience, take it or leave it, everyone.
Subjective opinions on opa604 series Classed A
I've used the opamp Class A polarisation in my opa2604 Arcam's Alpha 7SE output (original opamp was rc2114 -I think that's a tweacked version of ne5532).
I also try that mod in my opa2604 Arcam's Alpha 9 integrated amp in pre amp section (original opamp was tl072
- now you know why they sounded lazzy and with that valve-like sound...yeahhh...).
I also use opa134 in DC servo- it really amazes face to ne5534 (at least in that position, but that will be another topic
).
My opinion:
I think opa604 series are a bit of to mutch WARMMMM. Sometimes they sounded harsh and to mutch processed...meaning not good and very fatigating.
With class A polarization they still sound a bit warm but mutch more correct, plenty of bass, great highs, cleaner vocals, plenty of air, but I think (might me sugestion of mine) a bit less dinamic - maybe just less distorced and/or agressive.
Just my opinion!
Feedback is welcome!
I've used the opamp Class A polarisation in my opa2604 Arcam's Alpha 7SE output (original opamp was rc2114 -I think that's a tweacked version of ne5532).
I also try that mod in my opa2604 Arcam's Alpha 9 integrated amp in pre amp section (original opamp was tl072
- now you know why they sounded lazzy and with that valve-like sound...yeahhh...).I also use opa134 in DC servo- it really amazes face to ne5534 (at least in that position, but that will be another topic
).My opinion:
I think opa604 series are a bit of to mutch WARMMMM. Sometimes they sounded harsh and to mutch processed...meaning not good and very fatigating.
With class A polarization they still sound a bit warm but mutch more correct, plenty of bass, great highs, cleaner vocals, plenty of air, but I think (might me sugestion of mine) a bit less dinamic - maybe just less distorced and/or agressive.
Just my opinion!
Feedback is welcome!
Maybe this will interest you...
Guys,
Really nice thread, I can say (or confirm) that the OPA really sings when in class A. I´ve used it in an number of my (professional)designs, and when the power supply is excellent, you will get truly outstanding performance.
I'm selling my OPA 627AP and BP, as well as many other audiophile opamps. Check my post in the trading post forum.
I think this will give more DIY ers the chance to experiment with these opamps without having to pay the ludicrous prices that local shops are charching them (I've seen as much as 45 euro for an OPA 627 BP !!!!!).
with regards,
Xcel
Guys,
Really nice thread, I can say (or confirm) that the OPA really sings when in class A. I´ve used it in an number of my (professional)designs, and when the power supply is excellent, you will get truly outstanding performance.
I'm selling my OPA 627AP and BP, as well as many other audiophile opamps. Check my post in the trading post forum.
I think this will give more DIY ers the chance to experiment with these opamps without having to pay the ludicrous prices that local shops are charching them (I've seen as much as 45 euro for an OPA 627 BP !!!!!).
with regards,
Xcel
Hello all,
At the beginning of this thread, Carlosfm talks about adding the proper value resistor between pin 4 (-V) and pin 6 (output) to bias to Class A. Although it is not a perfect situation under load, he suggested to try it and assured everyone that this is all you need to do and don't make it harder than it needs to be.. Looks easy enough, why not. It would be nice to make the OPA627AP op amps do even more.
To figure out the value you need to apply the voltage to the formula. Everyone spoke of voltages like 12 volts and 18 volts. When I test pin 3 (+In) OR PIN 2 (-In) and common I get 2.6 volts and 6 volts on pin 6 (output) to common on my Rotel CD Player with new OPA627AP op amps. Am I doing something wrong or measuring at the wrong place? Any help would be appreciated! Thanks!
Regards//Keith
At the beginning of this thread, Carlosfm talks about adding the proper value resistor between pin 4 (-V) and pin 6 (output) to bias to Class A. Although it is not a perfect situation under load, he suggested to try it and assured everyone that this is all you need to do and don't make it harder than it needs to be.. Looks easy enough, why not. It would be nice to make the OPA627AP op amps do even more.
To figure out the value you need to apply the voltage to the formula. Everyone spoke of voltages like 12 volts and 18 volts. When I test pin 3 (+In) OR PIN 2 (-In) and common I get 2.6 volts and 6 volts on pin 6 (output) to common on my Rotel CD Player with new OPA627AP op amps. Am I doing something wrong or measuring at the wrong place? Any help would be appreciated! Thanks!
Regards//Keith
Hello, jarthel,
Thank you for taking an interest!!!!!!!
Here is the hyperlink to the TI specifications pages for the OPA627AP: http://focus.ti.com/lit/ds/symlink/opa627.pdf
Hopefully this can help! I will post the related part of the RCD-965BX schematic next!
Regards//Keith
Thank you for taking an interest!!!!!!!
Here is the hyperlink to the TI specifications pages for the OPA627AP: http://focus.ti.com/lit/ds/symlink/opa627.pdf
Hopefully this can help! I will post the related part of the RCD-965BX schematic next!
Regards//Keith
Hello,
In this thread I did not read about the experience of Hietbrink or fmak at Audio Asylum (AA) already in 2003. As fmak said: ‘In an AA- post on modifications to the SCD777ES, jhietbrink mentioned the use of the LM6172 bypassed by a 0.1 uF NPO ceramic betweeen V= and V- as the I/V opamp...Without the 0.1 uF cap, the sound was thin and unacceptable. Placing a 0.1 uF Rifa PPS cap across pins 4 and 8 'calmed' the sonics although the incisive trable quality was still there. Putting a 0.01 uF stacked 7XR cap in its place made matters worse. However, mounting the 0.1uF NPO has made the 6172 sound clear and yet with warmth. Timing is excellent and the mid range is much better than a current loaded AD826.The cap is not cheap though, and more expensive than the opamp! Amazing change in the behaviour of the 6172 which is otherwise well decoupled between V+, V- and ground.‘. You can read more here (and in associated posts):
http://www.audioasylum.com/forums/hirez/messages/156269.html
A review of someone else: ‘Believe it or not - the LM6172 actually sounds lush with the NPO ceramic caps in place. The bass is ample and powerful - and far more articulate than the bass of the OPA2604. The treble is extended and smooth - no hard edges. Cymbals shimmer and every brush movement can be traced. Now I know that some of you are thinking that this can't be a description of the LM6172 - or that I'm partially deaf. But what the LM6172 sounds like all depends on the bypassing. Without the right caps in the right configuration, the LM6172 can sound lightweight with a hard treble and diminished mid-bass. But with the right caps - the sound is glorious - at least for an op amp.’
Such NPO-caps seem to be advised by National and are for instance the Kemet Goldenmax brand in the C350 case size, Radial NPO 100V .1 uF (available from Mouser or Newark). I did not order them yet, and if someone would buy a bunch I would be interested.
A question about post 56 where Joe Rasmussen seems to have included a picture. Somehow I cannot see that picture. Am I the only one?
Best regards, Arjen.
In this thread I did not read about the experience of Hietbrink or fmak at Audio Asylum (AA) already in 2003. As fmak said: ‘In an AA- post on modifications to the SCD777ES, jhietbrink mentioned the use of the LM6172 bypassed by a 0.1 uF NPO ceramic betweeen V= and V- as the I/V opamp...Without the 0.1 uF cap, the sound was thin and unacceptable. Placing a 0.1 uF Rifa PPS cap across pins 4 and 8 'calmed' the sonics although the incisive trable quality was still there. Putting a 0.01 uF stacked 7XR cap in its place made matters worse. However, mounting the 0.1uF NPO has made the 6172 sound clear and yet with warmth. Timing is excellent and the mid range is much better than a current loaded AD826.The cap is not cheap though, and more expensive than the opamp! Amazing change in the behaviour of the 6172 which is otherwise well decoupled between V+, V- and ground.‘. You can read more here (and in associated posts):
http://www.audioasylum.com/forums/hirez/messages/156269.html
A review of someone else: ‘Believe it or not - the LM6172 actually sounds lush with the NPO ceramic caps in place. The bass is ample and powerful - and far more articulate than the bass of the OPA2604. The treble is extended and smooth - no hard edges. Cymbals shimmer and every brush movement can be traced. Now I know that some of you are thinking that this can't be a description of the LM6172 - or that I'm partially deaf. But what the LM6172 sounds like all depends on the bypassing. Without the right caps in the right configuration, the LM6172 can sound lightweight with a hard treble and diminished mid-bass. But with the right caps - the sound is glorious - at least for an op amp.’
Such NPO-caps seem to be advised by National and are for instance the Kemet Goldenmax brand in the C350 case size, Radial NPO 100V .1 uF (available from Mouser or Newark). I did not order them yet, and if someone would buy a bunch I would be interested.
A question about post 56 where Joe Rasmussen seems to have included a picture. Somehow I cannot see that picture. Am I the only one?
Best regards, Arjen.
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