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-   -   Sony CDP 707esd Help (http://www.diyaudio.com/forums/digital-source/217605-sony-cdp-707esd-help.html)

milezone 9th August 2012 02:11 AM

Sony CDP 707esd Help
 
I recently picked up a Sony CDP 707ESD at a good price in pristine condition. The player has a very odd but appealing and indescribable character -- like no other player I've heard. It's extremely detailed (maybe the most) but also presents music in a very laid back manner. It's not very dynamic I guess. The bass and weight of the notes are tremendous however. It seems almost contradictory however that's what I'm hearing.

I like it when it's playing well however theres a very glaring flaw that I'm hoping can be alleviated. On certain tracks (usually where there's lots going on or higher than normal dynamic swings) there's some very audible distortion and the player seems to lose control a bit. It weird however because some cds play through perfectly with no issues. It's not recorded distortion as I've tested other players and they've rendered the same passages with clarity.

I've read (on here) another member describing similar issues. One thing that alleviated the problem to a degree is switching the input from "fixed" to "variable" line. The problem here is that to get the player up to desirable levels you're increasing the output impedance from an already high 200ohms.

I'm wondering if there's a known fix for the issue. I'm considering replacing the clock, and certain key caps (not sure which ones would help if any).

Info or details on the issue would be greatly appreciated. Thanks in advance.

stephensank 9th August 2012 05:23 AM

It's possible you are hearing the ill effects of the horrible GIC filter used for low-pass. You can find out quite easily by simply removing opamps IC413 & IC513. There will be plenty enough passive low pass elements leftover that there's no worries about leaving it that way permanently, if you like the sound better, which I am sure you will.

There is NOTHING in the signal path that should be coming anywhere close to clipping/distorting on even the highest level peaks, so if there is distortion, there is something wrong with the unit. Normally, the symptom indicates bad output muting transistors, but this player thankfully does not use any. Depending on exactly the nature of the distortion, it is somewhat possible that you could simply have alignment issue, which would be indicated if similar material/levels distort with one cd and not on another.

PlasticIsGood 9th August 2012 06:07 AM

Service manual is available free if you don't have one, as is the datasheet for the Burr-Brown PCM64P DAC.

It's an epic machine, and worth fixing I think. If it has a glaring flaw there's probably a fault.

The variable output is simply the fixed one, after the volume control pot, and before the headphone amp. If the pot is set to maximum, then there should be no difference between the two outputs. If the problem reduces when the pot is adjusted, and compensated for with the amp's volume control, then that narrows down the problem to the output op-amps, your cables, and your amp's inputs.

Are your cables and amp inputs normal?
Is the problem the same on both channels?
What measuring equipment do you have?

It's a particularly complicated circuit. It would be worth finding the fault before you start swapping parts.

Mooly 9th August 2012 07:28 AM

A scope check would be useful here.

Have you tried a test disc disc recorded at 0db to see if that sounds clipped ?

A scope check of the front end (RF) wouldn't go amiss either. Some players can sound distorted when the RF is marginal and things get "busy" on the disc.

tvi 9th August 2012 07:59 AM

I brought one of these new when the first came out and one night I notice my tweeter quietly singing away to itself with nothing playing, got out my lowly scope and low and behold 5mV of 5MHz (from memory) on all the outputs, even without a disc inserted, sent it to Sony Service and they said it was acceptable. Eventually both tweeters failed

I think the ground is contaminated. One of the jumper connections seen here carries what I think is the offending signal.
http://lampizator.eu/LAMPIZATOR/REFE...D/IMG_5882.jpg

Never did fix(?) this as when I changed amps, it stopped, my Hiraga 30W Class A amps didn't care about the RF unlike the Onkyo I used previously?

You might find this of ineterst here

Rgds
James

milezone 9th August 2012 08:18 PM

Appreciate all the suggestions and information. Seems like some opposing opinions here. Part of me doesn't want to open the thing up as it's so well built. That being said, if there's a known fix for issue I describe I'd happily do it.

In my observations, what I'm hearing doesn't like a ground issue but rather distortion (low headroom due to crappy opamps). There's no real "noise" except during crowded/dynamic passages on certain cds. I hear nothing coming through my amp/speaker/tweeter though I'm also using a class A tube amp. I've read that the analogue section in these models can be improved. I'll likely try removing the opamps described. Are there any others that should be swapped out? Furthermore is there a likelihood that replacing the caps help the issue? Lastly I'm wondering if maybe there's a issue which could be alleviated by recalibrating it.

milezone 9th August 2012 10:53 PM

I don't have a working scope at the moment but will look into getting one. I'm in no rush to start bastardizing the player though I do agree it's worth investigating and being patient with. Any other suggestions are much appreciated. Thank you.

tvi 10th August 2012 02:56 AM

All about RFI and how to eliminate it in your studio...

Quote:

RFI can also have more subtle effects. Several years ago, it was shown by experiment that RFI can combine with audio signals in amplifier circuits. If the circuit is nonlinear (as most bipolar transistors are at radio frequencies), the RFI and the audio will intermodulate to create new audio signals not found in the original program. In other words, distortion.

This distortion usually shows up as hardness and harshness in the high frequencies. Sibilants splash, guitar pick noise is exaggerated, strings become steely. Sound familiar? This is the rap solid-state gear has had to endure from the beginning, and digital equipment still lives under its cloud. Much of the problem may be traceable to RFI intermodulation.

milezone 10th August 2012 05:06 AM

Really interesting article. Thank you!

milezone 4th September 2012 04:28 AM

Having had the player for almost a month now and using it as my main player, the issues mentioned in my initial post seem to have vanished. I truly think there is a burn in period for this chipset, potentially having to do with the heat of the dac chips. I know the player hadn't been used in over ten years and was sitting in the garage of the person from whom I purchased it. The player sounds great now.

If my odd hypothesis is true, I'm curious if this may have contributed to Sony's decision to abandon Burr Brown chips in favor of Philips chips (though keep in mind I'm speculating) soon after production ended on these player. Furthermore if anyone has similar experiences with digital components needing some time to run before functioning properly, please share.

Lastly, on a different note, does anyone have experience bypassing the oversampling in these players. Soon after picking up this one, I saw a similar player on ebay a 608ESD that had been modded to seemingly extreme proportions (dual torroids with two power cables coming out the back, lots of replaced internal wiring, teflon caps replacing the electrolytics etc.). The player is fairly beatup physically but it works quite well. In my experience it sounds about the same as the 707esd, even with all its mods though I need to spend more time comparing. I bought it as a means to learn a bit about what was done to it. Pictures of the 608ESD are posted below. The device near the transformers is a switchable filter. Unfortunately practically all the components have heatsink plates on them so it's a bit hard to tell whats going on. Furthermore the topology is fairly different from the 707esd. It seems one of the big changes was a simplified analog stage.


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