Re: SCD 777es DC servo AD712 replaced with CAP?
PhopsonNY said:Hi there Fmak,
Been doing some more research with the SCD audio path.
Someone in the Tweaker's asylum suggested eliminating the DC servo AD712 and installing a good cap there instead.
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As far as I am concerned, not at all. The coupling cap governs the tonal colour both in the bass and treble regions and I have not yet found a cap that sounds better than none, despite having speent a lot of money and gone to great trouble.
One may as well try getting rid of the output amp and taking the output from the buffer! This may work for systems with high input impedance, but not passive pres like I use.
Since you use a valve pre, there is perhaps no need for a coupling cap at all!
ad8512 instead of Ad712
Been doing some research elsewhere.
In article http://www.analog.com/technology/am...solutionsBulletins/amps12_01/SB-AMP-12-01.pdf
Analog designed the Ad8512 as a replacement to the ad712...
Would this work well as replacements in the buffer, filter and servo stages in the SCD 777es?
Been doing some research elsewhere.
In article http://www.analog.com/technology/am...solutionsBulletins/amps12_01/SB-AMP-12-01.pdf
Analog designed the Ad8512 as a replacement to the ad712...
Would this work well as replacements in the buffer, filter and servo stages in the SCD 777es?
I have a couple of AD8512 SO8 ICs sitting around, I plan to try them out as soon as the standard S08 to DIP BrownDog adapters get here, probably later this week. I will hazard a guess that these chips are not as good as using 2 AD8610 or AD825 with the BrownDog opamp adapter instead, but I guess I'll find out soon enough.
Have to use SO8s
Sony uses so8 ad712s in their audio board for their buffer, filters and servos so I do not have the option of DIPs hence the ad8610 is out for this application.
Your thread lead me to do the research so until the Ad 8620s show up, I am considering the ad8512s as they seem to be the direct dual replacements.
I would think they have to at least be better than the ad 712s.
Looking forward to hearing your opinions.
Sony uses so8 ad712s in their audio board for their buffer, filters and servos so I do not have the option of DIPs hence the ad8610 is out for this application.
Your thread lead me to do the research so until the Ad 8620s show up, I am considering the ad8512s as they seem to be the direct dual replacements.
I would think they have to at least be better than the ad 712s.
Looking forward to hearing your opinions.
Hi:
I tried to made the convertsion board for the dul to singal opamp. Then I used the OPA627BP for the I/V stage of the 777ES!
The result is good! And actrally there have over 40% improvement for the performance!
I compare this to the AD825 and the OPA627AP and the BP...
I found that OPA627BP is much much better then the others!
Will post the image later for the convertsion board....
About the zapfilter mk2 on the 777es
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I am not sure can be directly input with the current mode. Becoz I tried this on the 9000ES already. I found that there have about 8V output voltage there! I dont know why!
Finally I tried to connect with the voltage mode after the I/V satge. It works fine! And the result is great! But I think if can be connect with the current mode directly. It should be much better!
I tried to ask about this to the LCaudio but actrally still havent got the reply yet!
Cheers!
I tried to made the convertsion board for the dul to singal opamp. Then I used the OPA627BP for the I/V stage of the 777ES!
The result is good! And actrally there have over 40% improvement for the performance!
I compare this to the AD825 and the OPA627AP and the BP...
I found that OPA627BP is much much better then the others!
Will post the image later for the convertsion board....
About the zapfilter mk2 on the 777es
-----------------------------------------------
I am not sure can be directly input with the current mode. Becoz I tried this on the 9000ES already. I found that there have about 8V output voltage there! I dont know why!
Finally I tried to connect with the voltage mode after the I/V satge. It works fine! And the result is great! But I think if can be connect with the current mode directly. It should be much better!
I tried to ask about this to the LCaudio but actrally still havent got the reply yet!
Cheers!
Changed the ad712s >>> ad8512s
At this stage I feel that I am getting more daring in my intervention into audio tweaking.
Anyway changed the buffer/servo ad712 opmaps in the SCD77es last night to the ad8512s with relatively little difficulty. Very delicate work soldering surface mounts though.
Sonically, there is much greater transparency with this adjustment. The bass is audibly deeper and the the soundstage became undoubtedly deeper and wider.
It is funny that purely acoustic performances became clearer while amplified music sounds "different". Not quite got a handle on this yet.
Still not sure about the midrange...still cooler than when I had the ad8610 as the I/Vs. Only replaced these with the ad825s on Friday so I guess I have to leave it all alone now for everything to break in and get a good reading.
Overall the ad8512s are definetly better than the ad712s at this point.
When I get back in I might try the 8065 fastfets in the I/V and/or replacing the opa2123s mix amps with ad8512 also ?
any thoughts?
At this stage I feel that I am getting more daring in my intervention into audio tweaking.
Anyway changed the buffer/servo ad712 opmaps in the SCD77es last night to the ad8512s with relatively little difficulty. Very delicate work soldering surface mounts though.
Sonically, there is much greater transparency with this adjustment. The bass is audibly deeper and the the soundstage became undoubtedly deeper and wider.
It is funny that purely acoustic performances became clearer while amplified music sounds "different". Not quite got a handle on this yet.
Still not sure about the midrange...still cooler than when I had the ad8610 as the I/Vs. Only replaced these with the ad825s on Friday so I guess I have to leave it all alone now for everything to break in and get a good reading.
Overall the ad8512s are definetly better than the ad712s at this point.
When I get back in I might try the 8065 fastfets in the I/V and/or replacing the opa2123s mix amps with ad8512 also ?
any thoughts?
Just a note from down under...
I did the AD825 mod last night using the BrownDog adaptors. Very worthwhile, I think.
I personally feel the OPA2604 has a certain 'sound' - a bit tubby and restrictive, mildly overblown midbass, and slightly rolled off. In comparison the 825s sound very open and 'easy'. Wider soundstage, a nice natural feel.
I'm very interested in your exploits in the buffer/servo stage. Keep us posted!
I did the AD825 mod last night using the BrownDog adaptors. Very worthwhile, I think.
I personally feel the OPA2604 has a certain 'sound' - a bit tubby and restrictive, mildly overblown midbass, and slightly rolled off. In comparison the 825s sound very open and 'easy'. Wider soundstage, a nice natural feel.
I'm very interested in your exploits in the buffer/servo stage. Keep us posted!
-------------------------------------------------------------audiogenesis said:
I have been exploring opamp differences when current loaded by placing a buffered CRD between output and V-ve. The 825 with 1 mA CRD buffered by a 1 k resistor really sounds good. The 627 needs about 1.6 mA before sounding decent. Try it. Pecking order is:
resistative loading say 22-33k
CRD 1-2 mA
buffered CRD 1-2mA
Unfortunatley I cannot easily fit a buffered 2 fet circuit onto a SOIC to DIP adaptor but I'll try someday. Any comment about the possible improvement?
Each of the above steps I took gave significant improvements in terms of reducing sibilance and 'openess'.
Sorry need a little further explanation
Hi Fmak,
Read your last post and my knowledge of electronic nomenclature is limited.
What is a CRD? I presume you are suggesting connecting a resistor from the negative voltage feed to the output of each opamp.
Did you find that this worked better than the opamps on their own? What is the theory based on?
Did this make the opa627 sound acceptable and possibly better than the ad825?
On a separate question...I am interested in applying the ad8610 in the SCD777es. I was so impressed with their temporary role as I/V that I have feeling they will be better than the ad8512 as buffer/servo or even as mix amps.
.
1. AD suggests an LDO to reduce the voltage from 16 down to 12v. Is there a convenient possition to install one on the Sony's audio board.
2. Is it wise to reduce the B+/- rails as it might effect other unrelated parts of the Sony?
Might be dumb, but what do you think?
thanks
Hi Fmak,
Read your last post and my knowledge of electronic nomenclature is limited.
What is a CRD? I presume you are suggesting connecting a resistor from the negative voltage feed to the output of each opamp.
Did you find that this worked better than the opamps on their own? What is the theory based on?
Did this make the opa627 sound acceptable and possibly better than the ad825?
On a separate question...I am interested in applying the ad8610 in the SCD777es. I was so impressed with their temporary role as I/V that I have feeling they will be better than the ad8512 as buffer/servo or even as mix amps.
.
1. AD suggests an LDO to reduce the voltage from 16 down to 12v. Is there a convenient possition to install one on the Sony's audio board.
2. Is it wise to reduce the B+/- rails as it might effect other unrelated parts of the Sony?
Might be dumb, but what do you think?
thanks
Re: Sorry need a little further explanation
What is a CRD? I presume you are suggesting connecting a resistor from the negative voltage feed to the output of each opamp.
Did this make the opa627 sound acceptable and possibly better than the ad825?
1. AD suggests an LDO to reduce the voltage from 16 down to 12v. Is there a convenient possition to install one on the Sony's audio board.
2. Is it wise to reduce the B+/- rails as it might effect other unrelated parts of the Sony?
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Have a look at the tweaks section in audioasylum, message 31186 which explains reason. The easy way to do so on an adaptor is to use a current regulator (Vishay J50X) range, buffered by a 1k resitor from V-.
The 627 lost its mid/hi edge and was a lot more musical, though somewhat less open than the 825. It's a matter of opinion which is best; I prefer the 825. Also shows the 8610 to have an hf edge too.
You will have to make a new adaptor board and cut the supply rails in the Sony. With good design you can use lo noise regulators like LT1762 and 1964. Lots of work though.
Good luck; but you really should assess the thing on SACD, not CD.
What is a CRD? I presume you are suggesting connecting a resistor from the negative voltage feed to the output of each opamp.
Did this make the opa627 sound acceptable and possibly better than the ad825?
1. AD suggests an LDO to reduce the voltage from 16 down to 12v. Is there a convenient possition to install one on the Sony's audio board.
2. Is it wise to reduce the B+/- rails as it might effect other unrelated parts of the Sony?
---------------------------------------------------------
Have a look at the tweaks section in audioasylum, message 31186 which explains reason. The easy way to do so on an adaptor is to use a current regulator (Vishay J50X) range, buffered by a 1k resitor from V-.
The 627 lost its mid/hi edge and was a lot more musical, though somewhat less open than the 825. It's a matter of opinion which is best; I prefer the 825. Also shows the 8610 to have an hf edge too.
You will have to make a new adaptor board and cut the supply rails in the Sony. With good design you can use lo noise regulators like LT1762 and 1964. Lots of work though.
Good luck; but you really should assess the thing on SACD, not CD.
Only for I/V opamps?
From what I see it implies this is only applicable to I/V (ie current loaded) opamps?
I can see how this would be a major project with the brndog adaptors in place with the ad825s. I will prpbably try this later
Thanks for the info on the moddes ps rails. It does in deed sound like a lot of work.
At this point, I am wondering if I shoud go find a good design for a dicreet component audio stage that will allow me use the balanced output of the dacs or the I/V opamps.
Do you know of any good kits out there that I could build?
Maybe like or better than LC audio's Zapfilter?
thanks
From what I see it implies this is only applicable to I/V (ie current loaded) opamps?
I can see how this would be a major project with the brndog adaptors in place with the ad825s. I will prpbably try this later
Thanks for the info on the moddes ps rails. It does in deed sound like a lot of work.
At this point, I am wondering if I shoud go find a good design for a dicreet component audio stage that will allow me use the balanced output of the dacs or the I/V opamps.
Do you know of any good kits out there that I could build?
Maybe like or better than LC audio's Zapfilter?
thanks
Re: Only for I/V opamps?
Do you know of any good kits out there that I could build?
Maybe like or better than LC audio's Zapfilter?
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Why not try the ZAP filter, provided the band width is suitable for SACD. Geting LC top reply is a problem but may be the US agent can help. If you do, post the result.
Do you know of any good kits out there that I could build?
Maybe like or better than LC audio's Zapfilter?
----------------------------------------
Why not try the ZAP filter, provided the band width is suitable for SACD. Geting LC top reply is a problem but may be the US agent can help. If you do, post the result.
Cascoded JFET
I have been doing some research and a few people have applied the ZAPFILTER successfully to an SACD player and reported ggod results.
They have to connect after the I/V conversion and even then, there seems to be residual noise in CD mode.
I have found this design at the Borderly Audio site for a CASCODED JFET dac. It conncects in current mode and seems simple.
http://www.borbelyaudio.com/index36.htm
What do you think of it.
It seems different from Vacuum state as he uses a low pass filter instead of converting to voltage.
With the discreet I/V conversion, it might be possible to take advantage of Sony's error correction DAC stage.
any thoughts?
I have been doing some research and a few people have applied the ZAPFILTER successfully to an SACD player and reported ggod results.
They have to connect after the I/V conversion and even then, there seems to be residual noise in CD mode.
I have found this design at the Borderly Audio site for a CASCODED JFET dac. It conncects in current mode and seems simple.
http://www.borbelyaudio.com/index36.htm
What do you think of it.
It seems different from Vacuum state as he uses a low pass filter instead of converting to voltage.
With the discreet I/V conversion, it might be possible to take advantage of Sony's error correction DAC stage.
any thoughts?
ad8620 (Dual 8610) now available
Hey all,
Just checke the analog devises site
the ad8620 (dual version of ad8610 is now available)
cheers
http://products.analog.com/products/info.asp?product=AD8620
Hey all,
Just checke the analog devises site
the ad8620 (dual version of ad8610 is now available)
cheers
http://products.analog.com/products/info.asp?product=AD8620
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