Hi guys,
I have been searching for information regarding this cd player, which is a stock Pioneer PD-S904 that was heavily modded by Tom Evans.
http://www.tnt-audio.com/sorgenti/eikose.html
Information is scant and I was hoping that you can provide me with some details on the type of electronics mods that was done to this cd player.
All I know was that a Tricord clock was added, and the voltage regulators changed.
Btw, does anyone have the service manual for the Pioneer PD-S904 ?
Thanks
I have been searching for information regarding this cd player, which is a stock Pioneer PD-S904 that was heavily modded by Tom Evans.
http://www.tnt-audio.com/sorgenti/eikose.html
Information is scant and I was hoping that you can provide me with some details on the type of electronics mods that was done to this cd player.
All I know was that a Tricord clock was added, and the voltage regulators changed.
Btw, does anyone have the service manual for the Pioneer PD-S904 ?
Thanks
Hi,
I spoke with Tom Evans about his mods a few years ago, and can remember some details ...
Tom Evans uses a new output stage for the Eikos, powered by his super regs. The standard pioneer stage is based on a NE5532 as a SIL package - could easily be replaced using an adaptor.
Other mods are to fine tune the servo focus, pay attention to noise/decoupling of the servo, filter and DACS, bond a non resonant platform to the base of the player and build a high capacity outboard PSU.
Also, IIRC, all data and clock signals in the DAC are buffered with 1K resistors to reduce noise on the PSU lines. However it may pay to replace the bit-clock resistors with mayber 47 ohms in order to speed up the rise-time and reduce jitter. Tom removes them all, but I'm not sure that's a good idea.
Hope this helps.
I spoke with Tom Evans about his mods a few years ago, and can remember some details ...
Tom Evans uses a new output stage for the Eikos, powered by his super regs. The standard pioneer stage is based on a NE5532 as a SIL package - could easily be replaced using an adaptor.
Other mods are to fine tune the servo focus, pay attention to noise/decoupling of the servo, filter and DACS, bond a non resonant platform to the base of the player and build a high capacity outboard PSU.
Also, IIRC, all data and clock signals in the DAC are buffered with 1K resistors to reduce noise on the PSU lines. However it may pay to replace the bit-clock resistors with mayber 47 ohms in order to speed up the rise-time and reduce jitter. Tom removes them all, but I'm not sure that's a good idea.
Hope this helps.
Well, the Eikos costs a alot more than the stock pioneer, so MR. Evans has to justify that.
The main benefits will come from clocking and replacing the op-amps with something like LT1364s. You don't need a scope for better decoupling - try just fitting some OScons/Blackgates etc. at key locations. If I remember correctly, the laser board on top of the transport has a tantalum decoupling cap that can beneficially be replaced with something like an OScon.
If you change the op-amps, try removing the output coupling caps if DC offset isn't too high. In general, just do one mod at a time and learn as you go.
The main benefits will come from clocking and replacing the op-amps with something like LT1364s. You don't need a scope for better decoupling - try just fitting some OScons/Blackgates etc. at key locations. If I remember correctly, the laser board on top of the transport has a tantalum decoupling cap that can beneficially be replaced with something like an OScon.
If you change the op-amps, try removing the output coupling caps if DC offset isn't too high. In general, just do one mod at a time and learn as you go.
I have one of these players. I purchased it second hand as they are very hard to get hold of now. When I bought it the player was still at base spec. There were three extra upgrades to the player:
Lithos A - which upgraded the analogue circuits
Lithos D - which upgraded the digital circuits
And a power supply upgrade, which I believe seperates the power circuits for the audio circuitry from the main player electronics circuits.
Obviously one of the upgrades includes a later version of the Trichord clock upgrade.
Even though the player was a few years old I contacted Tom Evans and had all the upgrades done. At the time he was working on the Pulse Power Supply (a two box PSU) for the Vibe amp and he reckoned this would work extremely well with the EIKOS CD player to reduce even more noise. So I had a Pulse Power Supply fitted as well. The complete upgrade cost around £2500 from what I remember.
Lithos A - which upgraded the analogue circuits
Lithos D - which upgraded the digital circuits
And a power supply upgrade, which I believe seperates the power circuits for the audio circuitry from the main player electronics circuits.
Obviously one of the upgrades includes a later version of the Trichord clock upgrade.
Even though the player was a few years old I contacted Tom Evans and had all the upgrades done. At the time he was working on the Pulse Power Supply (a two box PSU) for the Vibe amp and he reckoned this would work extremely well with the EIKOS CD player to reduce even more noise. So I had a Pulse Power Supply fitted as well. The complete upgrade cost around £2500 from what I remember.
I'm afraid I don't know much about the electronics, and I've not taken the lid off it. There are some pictures of the insides of one of these players in one of the earlier issues of Hi-Fi+ magazine. I'll see if I can find it for you.
As you may remember the EIKOS is fitted with a special base, I'm not sure what this is made from. It also doesn't have the standard PDS-904 feet, but 4 yellow dot squash balls that it sits on!!
As you may remember the EIKOS is fitted with a special base, I'm not sure what this is made from. It also doesn't have the standard PDS-904 feet, but 4 yellow dot squash balls that it sits on!!
Thanks a million typeo. It is a great article.
From what I can gather from the pictures, Tom Evans did the following mods:
i. Replaced JRC5532 opamps with what appears to me like discrete amplification stages
ii. Replaced the regulators with custom-made regulators
iii. Replace aluminium electrolytic caps (at the analog stage) with tantalum caps
iv. Dedicated transformers for the analog stages
Thanks again typeo
From what I can gather from the pictures, Tom Evans did the following mods:
i. Replaced JRC5532 opamps with what appears to me like discrete amplification stages
ii. Replaced the regulators with custom-made regulators
iii. Replace aluminium electrolytic caps (at the analog stage) with tantalum caps
iv. Dedicated transformers for the analog stages
Thanks again typeo
typeo said:
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.