Tube CD Player

Hi guys,

Thought I'd share this project here.

It's a tube cd player for one of my customers.

Overall build up of the player consist of :

1) Superb chassis recycled from a very reputable cd player but kena lightning strike so almost everything ori in that player went kaput ( I let u guess it).

2) CDrom SPDIF output. The digital output level is a bit too powerful for normal CS8416 of the DAC's input so I've attenuated using a 330/100 ohm resistor before feeding it to the DAC.

3) DAC using a Monica 1 with passive I/V converter with reclocked I2S signal.

4) The output of Monica at about 0.6v is fed to a 6922 tube in common cathode amplification stage. Voltage supply is 140VDC.

5) Power supply is a highly dedicated one. Each function of the above item has their own PSU.

--> CD Rom's 12V and 5V is supplied by a highly modified SMPS with plenty of AC filtering and fast output caps.

--> CD Rom's controller 5V is taken from the SMPS

--> Monica's 12VDC is supplied by its own transformer

--> Tube output stage is supplied by its own 120VAC transformer rectified using MUR860 fast soft recovery diode bridge

--> Tube's filament supply is supplied by a 6VAC transformer and then rectified to DC then supplied to the filament via 10ohm resistor.

Preview

Wikin,

Nice job!

yeah bro! we need more pictures.

Wow nice looking DIY CDP. Cant wait to hear yr comments on the SQ.

Thanks for the support guys.

BTW HF4Sale site was really difficult to access for the past 24 hrs. Now seems ok.

Ok back to the details of this player.



I used this cdrom controller kit as the basics for controlling a CDRom - yes CDROM, not a DVDrom. Why? Because it seems that the tray of a CDRom is just 1mm narrower than most DVDRoms which gets through the front faceplate opening of the player just ngam ngam.



The easy part is to purchase this kit and make it to work with the CDRom.

The hard part is to make it integrate with the existing player so that the beautiful buttons of the old player can be re-used without having to drill new holes in alignment with the CDRom's new buttons.

How to do just that?

nice work! first class modification bro!

jat wrote:nice work! first class modification bro!

Thank you bro

Wikin wrote:
The hard part is to make it integrate with the existing player so that the beautiful buttons of the old player can be re-used without having to drill new holes in alignment with the CDRom's new buttons.

How to do just that?

The CDRom kit's display is actually embedded behind the front panel. The 4 buttons of the original panel has their signal tapped/ hard wired to the controller.


Darth Vader unmasked.


A new 16 strand ribbon cable was soldered to the Kit's LCD display and the signal was brought to the front.

The 4 original and beautiful push buttons were retained. You can see the hard wired signal cables being tapped. From left to right, their respective functions are Previous, Next, Play, Stop.

It was a bit tricky to perform this hard wiring as the signal from the Kit's push button is crossed all over the place in the PCB and I wanted to pull as minimal wiring as possible.

The ideal number of wiring to pull from the kit's push button panel is just 6 --> Stop, Eject, Play, Previous, Next, Ground.

On the other end of the front panel's PCB locates the eject button and Remote control sensor. They are also hard wired.

From the top view of the LCD display, the front plate just barely sandwich it properly. I got lucky this time.

Once the metal perimeter trim is inserted between the front plate and the chassis, all is covered.

Here comes a shot of the guts.




The left side of the chassis locates all power supplies, middle is the CDRom and the right side locates the Monica+Reclocker and the tube output stage.

Between the PSU and CDRom is the controller.

At the player's first power on, it ran for just 2 seconds and then the whole house tripped ! Yes it literally tripped the switch box of my house I thought WTF !

Not believing my luck, I re-activated the mains and switch on the player. My heart was actually pounding pretty fast for fearing something would blow up. After 2 seconds it tripped the whole house again...

Back to the drawing board.

Tripping the switch box means that something is either shorting or there's a leaking current going back to the earth wire.

Using a multimeter and setting it to the lowest ohm setting (with beeper on), I started probing around the mains inlet and around the transformer's primary circuitry to check if there's a short somewhere.

Nope none.

Next I switched to the Mega ohm setting, connecting 1 probe to the earth pin of the player, and the other probe sniffing around to see if there's a Mega ohm connectivity linkage to the earth.

Aha found it at the secondary side of the high-voltage transformer.

Cursing myself for being so careless, I actually used a 240/120V Autotransformer instead of a 240/120V Normal Transformer. This transformer supplies the 140VDC to the Anodes of the 6922 Tube. It seems that by using an Autotransformer, the secondary side, when connected to a bridge rectifier, leaks current back to earth.

So what I did was to remove that Autotrans and replace it with a Normal transformer from my collection of transformers.

All is solved and the player can now power on properly.

phew... too technical & complex for layman but excellent job. So does it sound better than its predecessor?

boxer wrote:phew... too technical & complex for layman but excellent job. So does it sound better than its predecessor?

Actually I wanted to do more coverage of foreplay caressing every inch of the player but seems that several of you can't wait for the cum-shot so oklah I'll cover the sound quality


It will be too easy and definitely biased to say that the current player is great sounding as it's my labour of love.

Also worth mentioning about the predecessor player is the extensive amount of modifications done - having all Black Gates capacitors worth RM2K on its PCB!

Comparing the predecessor player and its reincarnation, they are 2 totally different characters akin to a comparison between Honda Civic Type R vs. Toyota Harrier 3.0 respectively.

Both delivers powerful performance in their own right. The Honda Type R is very fast with great pick up and great top speed, accurate on the corners, BUT, try driving from KL to Penang non-stop.... I bet you'll end up in a fatigue mood.

The Toyota Harrier 3.0 is also a powerful vehicle which delivers power in a different way that is much more comfortable, silky smooth and relaxed. It doesn't take the corners as well as the R, but going to Penang will be a breeze. The Harrier is also a bigger vehicle which can be linked to its sound. Big sound.

At the end of the day I want my music delivered big bold without fatigue so you can already guess which is my vote.

2 very critical steps was discovered and then implemented inorder to eliminate noise that is heard on the speakers.

1st is the incoming AC filter with a common mode choke and x + y rated capacitors.
I find this very important because without it, the SMPS power supply tend to modulate the AC supply and then noise can be heard thru the tweeters.



2nd is the cdrom chassis grounding. This is also important.

CDP with auxiliary input.

This is a specially modded so that the user can have 1 additional analog input directly into the tube stage.

The output from Monica is routed to the front panel where there is a 3.5mm stereo female jack being connected. The jack's output will be connected to the tube stage.




What's the aux input used for?

An Ipod dock.

A comparison was made between the CD Rom vs an RM110 Philips DVD player as a transport feeding the Monica DAC.

Verdict: No fight... the CD Rom really kills the DVD player in all aspects of the sound. Clarity went up several notches and not only that, the sound is just more involving because we get to hear and feel more of the singer's nuances.

Replaying some non audiophile CDs, e.g. Michael Jackson's Man In The Mirror, this track is particularly not an easy feat to reproduce as its musical mixing is very busy. Playing back with poorer systems, Michael's voice will be recessed inside the sound stage one can't hear it clearly.

With this CDP, I can almost feel Michael is singing in front with full emotional impact. The starting track has its treble information floating across sound stage totally unattached from the speakers. Low bass from this track is weighty enough to satisfy bass freaks.

If I had to nit pick on the sound, I would say that the amount of tube sweetness and bloom in the mid band may not go so well with systems that already have a sub woofer. One might have to tune down that sub otherwise it's easy to blame the CDP for having excessive boom.


Going on to the sound of DOCKed Ipod, this Philips Dock was modified whereby I tapped the line signal from its preamp stage. That means the DOCK's preamp stage is routed out using phones 3.5mm jack and then input into the front of the CDP where the signal will be fed to the tube stage.

The sound takes a much brighter presentation albeit with less bass quantity. Clarity is still good but it's just not as good as the stock CDP as if dropping 2 notches down.
This is not too shocking as the build of the DOCK's analog circuitry is just regular mid-fi construction. It's opamp is powered from just 8vdc single supply and the coupling caps are using SMT ceramics (hence bright bright sound).

All in all, as a standalone CDP I'm not shameless to say that this CDP can smoke many commercial offerings even in the RM five digit figures. Listening to this CDP can make people wonder whether if our audio technology has really advanced in the right direction or not - or are all those numbers in bits are just a marketing and sales pitch.

cheers.