| PhopsonNY |
Hi there,
I fully admit I am new to DIY at this level, but I was wondering what anyone thinks of replacing the audio board opa2604 opamps in the SONY SCD 777es with the new Analogue Devices AD8610 opamps?
My research suggests that this opamp outperforms the opa627 with the added benefit of a more neutral midrange and speed of the ad825 with deeper bass response.
Any thoughts or suggestions?
TIA |
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| sonnya |
The max. working voltage on the AD8610 is +/-13.5V
Check the rails. Normaly it is +/-15V or more :(
If you mount them. Check if they oscillates at the output?. If the oscillates maybe they need better decoupling.
Sonny |
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| PhopsonNY |
Hey Sonnya,
thanks for the feedback.
Lcaudio.com and audiocom-uk.com make dual AD825 modules with decoupling capacitors on them.
If I replaced the AD825s ont hes modules with the AD8610s, is you think that might make it work? |
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| sonnya |
Should be no problem.
Sonny |
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| John S. |
| The 2604 is supposed to be a pretty good IC. As a fellow 777 owner, I've been tempted to get mine modded, but the fear of having it develop problems and the need to use the warranty have kept me from doing this. I hope and pray that I never need to send it out. I gather that there have been some issues with these units regarding the spindle/motor/sled section. Y ou may want to think twice about doing any mods. I DO admit that the temptation is great though. |
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| PhopsonNY |
Hi John,
I must admit this is an issue, but I have lready made several mods to my 777 and I am extremely happy.
If you are ver tempted here are the 2 mods that you have to do first. I found that they greatly improved my players perfromance.
I also shanged a number of passive components, but they are another story.
1. Replace the rca jacks with WBT, CARDAS or other high spec jacks and at the same time you simply must do #2.
2. Wire the audio signal directly to the jacks from the audio board bypassing the pin board.
3. Reconfigure the grounding.
See the following llinks:
http://www.audioasylum.com/forums/h...ages/41691.html
http://ryoko.telhope.com/~tkchan/777mod/777Mod.html |
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| John S. |
| I've done this kind of stuff to lesser players,along with changing output IC's. I'd like to see someone come out with a kit of parts and instructions for doing a full mod. |
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| PhopsonNY |
modwright.com has a whole tube output stage he offers.
I am actually waiting for;
www.vacuumstate.com
they have a kit that taps the vc24 chip and bypasses the rest of the audioboard right to a whole new set of output jacks.
They take the bitsream feed and use a low pass filter with on a separate pc board with its own power supply.
They actually give a choice or single ended or balanced outputs.
This will shortly be available as a full kit with instructions for the SCD777es.
:rolleyes: I am indulging my hobby as I know the vacuumstate's kit will be better than the opamps, but I would like to see how much better it is than the best opamp driven signal. |
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| John S. |
| The modwright site seemed to be disfunctional,so couldn't find anything about them. And I'm somewhat leary of circuits that use the 6DJ8/6922/ECC88/7308 family of tubes. I was a former owner of an Audible Illusions preamp that I became very dissatisfied with. Sounded more like solid state.After a bit of reading around, I discovered that others felt the same about equipment that uses this tube. I've found a 12AX7A(I use 5751's) based preamp more pleasing to my ear, but as they say... YMMV. Each to his own. |
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| Brussel Sprout |
Vacumestate's board sounds interesting. I wonder if the LCAudio Zap Filter can be connected directly to the bitstream output? - It's a bit cheaper than the Vacumestate mod, but doesn't include labour...
-Mark. |
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| fmak |
| The AD8610 seems ideal. However it has high open loop gain and my own experience favours the lower gain AD825. Have you listened to the former; I am very interested. |
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| PhopsonNY |
Have not tried the 8610 or the 825 yet.
I am trying to layout a plan of attack first so as to increase chanses of success.
I will probably get Audiocom-uk's OPA627 dual module with its decoupling capacitors and replace the 627 with the 8610s on the modules.
This is probably better fit than the AD825 modules.
Here is a description of the Sony's circuit:
http://www.audioasylum.com/forums/h...ages/33130.html |
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| sonnya |
AD825 and AD8610 have another pin layout than usual!!!!
Sonny |
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| fmak |
SCD1/777 Mods
I have tried the OPA249 and was not impressed. This is a high gain design compared to the AD285. Suggest placing IC sockets and trying different ICs. You can easily make your own 825 DIL units from conversion boards from RSComponents much cheaper. The decoupling capacitors don't matter. If you insist you can put these in yourself. |
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| PhopsonNY |
The mod was a lot easier than I first suspected as thanks to Fmak, I did not need bypass caps in the SONY SCD777es i/V conversion.
As I was not a pro, I had to be carefull and hense it was time consuming.
Works well and much better than the original OPA 2604s.
Still burning in...will see what final sound is.:) |
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| fmak |
| quote: | Originally posted by PhopsonNY
The mod was a lot easier than I first suspected as thanks to Fmak, I did not need bypass caps in the SONY SCD777es i/V conversion.
As I was not a pro, I had to be carefull and hense it was time consuming.
Works well and much better than the original OPA 2604s.
Still burning in...will see what final sound is.:) |
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Reread the 8610 spec sheet. One aspect worries me somewhat, and that is the long settling time. The spec sheet shows prolonged ringing into capacitative loads.
Still, if it sounds good, that is what counts. |
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| PhopsonNY |
Thanks for the feedback.
I will wait a week for burn in and then if I have the nerve to do this again, I will test the AD 826 and compare:rolleyes: .
I do wonder though that if I have to leave the AD826 in for 3 weeks to burn in, will I still be able to tell the difference between it and the AD8610.
The thing is of course to let the AD826 burn in and then try the AD8610 again...:(
A lot of opening/closing and soldering and desoldering.
After last night, I planned to only go back in to put in the VSE mods and your capacitance mods in the digital section.
The AD610s do sound very musical tho...
What are you doing next? |
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| fmak |
[QUOTE]Originally posted by PhopsonNY
[B]Thanks for the feedback.
I will wait a week for burn in and then if I have the nerve to do this again, I will test the AD 826 and compare:rolleyes: .
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I find that it is the long term acceptability and mussicality that counts, and that means a few weeks at least.
I am looking at DVD-A. See my post on the Technics A10 which I took completely apart - very brave and it took a long time to develop the inclination!!!
The answer is a dCS DAC and drive -- but I can't afford it.:( |
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| jarthel |
I just compared an AD826, OPA2604, OPA2132P and OPA2228. I like the OPA2228 best. :)
Jayel
ps. my player is not the sony SACD player. :) |
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| fmak |
| quote: | Originally posted by jarthel
I just compared an AD826, OPA2604, OPA2132P and OPA2228. I like the OPA2228 best. :)
Jayel
ps. my player is not the sony SACD player. :) |
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Can you pl let me know which position you tried it in, I/V, filter, ot buffer/output? Also what CDP?
:) |
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| PhopsonNY |
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.
What do you think about this? |
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| fmak |
[QUOTE]Originally posted by PhopsonNY
[B]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!:) |
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| jam |
Fmak,
If it a servo is not done correctly its effects are far worse than a good coupling capacitor. I would try it both ways and compare the results. You might be surprised.
Jam |
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| fmak |
[QUOTE]Originally posted by jam
[B]Fmak,
If it a servo is not done correctly its effects are far worse than a good coupling capacitor. I would try it both ways and compare the results. You might be surprised.
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I know.In our case, SCD777, there is no evidence that this is so. The player has superb bass and very good overall sound. Removing the servo can cause problems with the buffer amp etc. One should measure first and this is not easy with the 777 unless one buys or makes up the extension kit.
If something ain't broke, why fix it? |
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| PhopsonNY |
Been doing some research elsewhere.
In article http://www.analog.com/technology/am...B-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?:confused: |
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| morsel |
| 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. |
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| PhopsonNY |
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.
:rolleyes: |
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| hatasa |
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!:p |
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| fmak |
[QUOTE]Originally posted by hatasa
[B]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!
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I don't find this; the 627 is very clinical, quiet but hifi sounding in the I/V popsition of the 777. The 825 is much more musical; less impressive sounding but provides for longer term enjoyment. This is in a unit that has the carbon films replaced by Vishay 102s. The Rikkens have never appealed to me except perhaps in some valve units.
My own suspision is that the 627 settles far less quickly than the 825 (see spec sheets) and the bandwidth is not great for the hf pulses of SACD. |
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| PhopsonNY |
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 ?:rolleyes:
any thoughts? |
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| audiogenesis |
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! |
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| fmak |
| quote: | Originally posted by audiogenesis
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! |
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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'. |
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| PhopsonNY |
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.
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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?:rolleyes:
thanks |
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| fmak |
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. |
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| PhopsonNY |
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.:eek:
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.:rolleyes:
Do you know of any good kits out there that I could build?
Maybe like or better than LC audio's Zapfilter?
thanks |
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| fmak |
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. |
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| PhopsonNY |
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? |
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| dorkus |
| oops i typed up a response to the servo question (with or w/o) but then i realized jam and fmak had already discussed it, so i erased it. |
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| dorkus |
sweeeeeeet.
i might stick these in my Sony NS500V SACD player but i wonder if i should fix the awfully noisy switching power supply first... |
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| fmak |
| These things should be banned unless they can be silenced!!! |
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| PhopsonNY |
AD confirmed that these opamps should work fine to a maximum of 26v when voltage is applied to a single rail.
ie is ok up to
+0v and -26v
or
-0v and +26v...
They say it is the total difference that matters... just be that the voltages are well controlled
This is good news for those of us with the SONY SACD Players...
I have the ad8620 in the Buffer/servo position replacing the ad712.
So far Works just fine with single rail voltages of 16v...
Had the ad8610 dual modules in I/V position and they failed, but stupidly forgot to replace a connection when closing up and this may have effected the opamps |
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| NAP 160 |
| quote: | Originally posted by PhopsonNY
Hi John,
I must admit this is an issue, but I have lready made several mods to my 777 and I am extremely happy.
If you are ver tempted here are the 2 mods that you have to do first. I found that they greatly improved my players perfromance.
I also shanged a number of passive components, but they are another story.
1. Replace the rca jacks with WBT, CARDAS or other high spec jacks and at the same time you simply must do #2.
2. Wire the audio signal directly to the jacks from the audio board bypassing the pin board.
3. Reconfigure the grounding.
See the following llinks:
hi john i have done this mod on two 777es players i have never used the chip you qote. but i replaced the burr brown chip with the AD826 AN and the sound stage opens up, lots more deital bargin upgrade for the price. all the best john
http://www.audioasylum.com/forums/h...ages/41691.html
http://ryoko.telhope.com/~tkchan/777mod/777Mod.html |
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| Joseph0 |
unfortunately, if the internal schematic of a soic8 dual op-amp is the same as an audiocom adapter, making two single soic8 opamps into one 8-dip dual, you are providing each of the two opamps in the ad8620 +16VDC and -16VDC, 32VDC, exceeding the 26V limit.
however, the 777es/scd-1 schematic does show the opamps inside the ad712, one receiving a single supply of +16VDC, the other -16VDC, and not a +/-16V dual supply for both, (as though the amps inside AD712 are two completely independant amps with single supply rails). If the V+ and V- pins of the ad8620 are not connected to each opamp, a single V+ for one amp, V- for the other, the 26V limit wouldn't seem to be exceeded.
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| Joseph0 |
the 'regulator amp', IC107, IC207 on Sony board, two of four uses of AD712 is actually supplied +/- 9VDC, so AD8620 is certainly ok there.
the 'line amp', IC104, IC204 is the one supplied +/-16VDC. |
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| peranders |
| Are you aware of that you have waken up a thread from the stone age? |
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| Joseph0 |
| nope. I'm trying to find reason not to unsolder the AD8620's I put in 'line amp' position before finding +/-13V limitation. |
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