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The CD Transport

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I start with a copper plate bottom, size 5.8 x 8 x 3/16". The wooden frame (Wenge) is 6.4 x 8.8 x 1.5". There are 6 screws attaching plate to a frame and 3 spikes acting as feet.

I cut out the display opening later, after top acrylic plate is trimmed. There's also an RCA socket and opening for an umbilical cable in a rear panel.

There are 2 pairs of standoffs (1" long) mounted to a plate: two 3/8 are for mechanism support, the other two for buttons pcb.
 

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I modify the original display board next: it's trimmed, and what (needed) traces have been cut, they are now replaced with hookup wire. Unnecessary components in top layer are also removed. I also trim plastic display board housing. It can be removed by taking out 2 screws and desoldering IR receiver, LED and display pins.

There are 5 connection points to the switches:

2 common for all buttons
S stop
P play
B back skip
F forward skip

The buttons are spread 0.7" apart. The display is attached to wooden frame with a single, isolated head, screw. There is additional TOC switch mounted on a side (normally closed type).
 

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The schematic show external PS. Two wires from PS are connected to the pads where choke was. Since BG FK is hard to find these days, I use BG STD with BG N 4.7uF bypass.

I add two output resistors: 300/100 Dale (you may also consider S102/Caddock) and in place of C916 I instal BG N, either 47/50 or 33/16 depending on availability.
 

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Thank you Peter.

Like so many threads here it is the nature for the truly useful stuff such as construction guidance to get lost within a morass of comment and questioning. Then someone new joins the thread and repetition is added!

That you have chosen a topic out of your many contributions which has the lowest commercial return for you is noted and admired!
 
Well, I just follow my signature: “Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” ;)

Getting back to the transport, the last thing is a top panel. I was initially using 1/4" acrylic, but after I tried thin metal top, I though that 1/8 acrylic would be nicer. Most common choice is clear frosted type, as it's easiest to maintain, but recently I was tempted to go with darker color and tried tinted acrylic. The shiny finish is quite impressive, but any fingerprints show right away, so I hand brushed it with quite good results. The look is similar to brushed, anodized aluminum.

I cut out the laser opening first and align it over the wooden frame, then figure out where 4 mounting holes should be placed. After attaching slightly larger panel on top, I trim the sides with a router.

The buttons are 0.314" dia. and I got them years ago surplus. When I run out, I will be making them out of aluminum rod.

I was initially using a bit more complicated front panel which was made out of aluminum with acrylic insert, but later figured out that simple piece of tinted acrylic fits here much nicer and is way easier to make (3.25 thickness). It's also clear enough to provide good visibility.
 

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That concludes the commercial version of a transport, which performs very well based on comments I'm receiving from end users.

Recently, I was experimenting with clocked output and the idea is certainly worth pursuing.

While checking some of the Lampizator ideas: http://www.diyaudio.com/forums/digi...-improving-motor-cec-mabuchi.html#post1926921 I had a chance to compare the clocked output of CEC TL0 vs a simple resistive divider output. In the end the clocked output appeared to be better and for some time I was thinking on trying it with Shigaclone. The guys on Audiostereo Forum made more experiments already, but nothing so far has been documented well: Robimy shigaraki transport / CD Flatfish - Do It Yourself - Forum Audio - Audiostereo.pl

So let's start from the beginning.

Attached is original CEC TL0 clocked output schematic and pics of the boards. "The master oscillator (a crystal which looks like Citizen) controls not the transport mechanism but the output stage, a flip-flop chip that could be considered a 1-bit FIFO. The output data thus have the maximum timing precision, which is where it is needed. The mechanical drive is slaved to the output stage".
 

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This is how it's being done in ML31.5: Stereophile: Stereophile: Mark Levinson No.31.5 Reference CD transport

"More important from a sound-quality point of view, they remove the Philips-supplied 1000ppm-accuracy oscillator from the servo board and replace it with a TCXO (Temperature-Controlled Crystal Oscillator). Spec'd at 5ppm and run at a 256fs rate, this is mounted on its own sprung printed circuit board next to the output. And even more important with respect to sound quality, the transport has changed conceptually. That master oscillator controls not the transport mechanism but the output stage, a flip-flop chip that could be considered a 1-bit FIFO. The output data thus have the maximum timing precision, which is where it is needed. The mechanical drive is slaved to the output stage and therefore needs to be able to respond to its demands, which is why a 2x drive mechanism, with its inherently fast response, comes in useful. (This topology, referred to by Madrigal as Closed-Loop Jitter Reduction, or CLJR, was developed for the less expensive No.37 and Proceed CDD transports.)"
 

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And this how I prototyped it in my transport. Please see attached edited CEC schematic (according to board layout the RCA output is actually taken from pin 9 of the flip-flop)

I added a small board with two chips and few additional parts (used exactly same chips as CEC, some experimenting here with different types maybe worthwhile and will follow), crystal is Citizen and output transformer Scientific Conversion. I didn't use output coupling cap, it's not really needed here as long the DAC does not show any input DC offset.

I didn't use any additional regulator (TL0 does not use one either) the power, data and ground are simply taken from main board, another wire connects clock signal from output board to main board (use resonator pad which is further away from LC78601 chip)

How does it sound? Well, I didn't find anything wrong with the transport in a first place, with a mod though, it has a bit less of edginess and thin sounding, which some people may find sort of annoying. It produces sounds that are better defined in space and possibly more refined. It's certainly worth trying and I would be interested how others find it.
 

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Now comes the PS part.

48VA Hammond transformer (166L24) fits perfectly in a Hammond 1590T enclosure. The diodes are mounted directly to connector socket and the whole thing came out quite elegant and simple.
 

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