Finally, an affordable CD Transport: the Shigaclone story

I have a question for those who are messing with the Shigaclone longer than me.
I am using the Shiga with an Audiosector NOS DAC and have quite some problems to get it to lock...
Sometimes it will play music just fine... sometimes I only hear distant hum which makes me think of a grounding issue.
Neither DAC nor Shiga are connected to earth, all my other gear is...

Anyone encountered a similar issue or has some advice?

I had a problem that sounds similar. In my case it turned out that the culprit was the connection between the Shiga and DAC - one of the joints linking the digital ground to the socket was loose.
 
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Just my 2 cents on the mechanism tests:

From my test, i have 2 mech of each type and although it's very critical on either , to get the right distance to lazer to have good focus and lock, the puck version gives consistently better sound, in my case at least.

Maybe because CD vibrates less...have to do more tests.

The puck version on the other hand would maybe benefit from a better magnetic puck, the stock one having a lot of side play represents an unstable rotating mass....bound to introduce focus distortion.

The previously posted new magnetic puck version might be worth a try but the lighter it is the better is my reasoning.
 
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The biggest issues I see with a magnetic puck are (1) the mass of the magnets and ferrous mating coupling surface, and (2) getting it balanced.

1) Mass is a - for accelerating the disk to speed, but may help maintain constant speed. Probably a wash. However, the mass may impact the servo feedback since it is the equivalent of capacitance in an LC circuit.

2) magnetic position is critical for rotational balance. Any eccentricity in the position of the magnets/coupling results in out of balance mass. This will cause vibration, modulation of the bit time, and poor tracking.
 
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The biggest issues I see with a magnetic puck are (1) the mass of the magnets and ferrous mating coupling surface, and (2) getting it balanced.

1) Mass is a - for accelerating the disk to speed, but may help maintain constant speed. Probably a wash. However, the mass may impact the servo feedback since it is the equivalent of capacitance in an LC circuit.

2) magnetic position is critical for rotational balance. Any eccentricity in the position of the magnets/coupling results in out of balance mass. This will cause vibration, modulation of the bit time, and poor tracking.


Agree with all the above but it still beats the other option because the CD remains on a flat plane with fewer vertical vibrations.
 
Jut another piece of the puzzle. Tonight I went back at the 3 ball mech. I had also noticed that it was more sensitive to marks on the CD than the regular transport (I have 2 shigaclones side by side at the moment to test, one with the normal puck and the other with the 3 ball type). Anyway I seemed to remember somewhere from the bowels of my mind that someone had mentioned a problem like this and that it was due to a slight bend in the mech. So I slackened off the mounting bolts (mounted on 2 stands as per the okapi mods) and lo and behold!! the sound all came right!!

I must have just cranked down on them too hard. I went back and just "pinched" the 2 screws tight and its all AOK now. Sound is indistinguishable from the magnetic puck now - good news I think for everyone. It is still a little more sensitive to marks on the CD than my other mag puck shiga, but not as bad as before. This may even be due to variation from one selection to the other.


This brings me back to one of the early discoveries in this thread - for any new shiga people here, please bear in mind that the physical mounting of the mechanism is very important indeed. 2 posts in opposite corners, fixed to high mass, and that whole mass sitting on a compliant base, eg 4 springs. It would be well worth each of your time to go back through all 5413 posts on this thread so far and quickly read through them. Also, I have most if not all of the PDFs and critical drawings etc saved (I think) if people need them. Might not be any harm to start a new "building the ...." type thread if the group buy comes off. The first post of that thread will be editable forever, and pertinent pdfs, jpegs, main findings about power supplies, clocks etc etc and so on could all be added there to keep them in one place as the thread grows.


Fran
 
Here's the main ones:


This is a collection of stuff..... some not of interest maybe anymore. The acrylic puck is the actual 47 labs one. I also have the original okapi mods PDF, but its too big to upload here. If a google search doesn't turn it up for you, send me a pm with your email address and I'll email it to you. Likewise for the EZ31 manual.
 

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Oh yeah - another thing. I've mentioned them a load of times in this thread but no-one has used them (here) other than me.

The shiga puts out a TTL level S/PDIF signal - too high for most DACS. Most use a resistor combination to drop the level to 0.5V, using all sorts of combinations of fancy resistors, riken and the like to get there.

A better sounding alternative (IMHO) is to use RF attenuators to drop the signal to 0.5V or lower. These attenuators are precision lab devices available from minicircuits.com and cost about 12-15$ each. Look up part# HAT-6-75. Its the precision 75dB ones you want.
An externally hosted image should be here but it was not working when we last tested it.


I would recommend anyone to try them, maybe buy 1 x 6dB, 1 x 10dB and 1 x 15dB. You can stack them in series to try out different levels. Note that they are BNC only, so you want to figure on that.

Main page here: http://www.minicircuits.com/products/attenuators_coax_fixed.shtml

HAT-6-75 here: http://www.minicircuits.com/pdfs/HAT-6-75.pdf

Fran
 
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Here is the schematic of the new shiga.
There are few modifications who will allow you to improve further the performance of this transport:

1. entire LC78601RE audio section removed
2. option to use original oscillator or a low jitter XO, aka Tentlabs.
3. separate power supply for each chip
- external 8V for BTL driver LA6541
- +5v for display IR using build-in LA6541 regulator
- power supply for LA9242M is split in two separate sections. One +5V for RF section - pin 64 -, laser and pin diodes and second +5V for servo and digital section - pin 56.
- last +5V regulator is for LC78601RE
4. option to use two regulated +8V. One will go directly to LA6541, second for cascaded LT1763-5 regulators.
5. 4 button display board
6. s/pdif is on board - R50 and R51

Except display and IR all other +5V regulators are low noise LT1763-5 and will be on main board.
You don't like this approach ? Just strap each regulator section using 0ohm resistors - R25, R44

If you have any observations and/or further modifications you like to be included, please let me know.
Please note that this is not final schematic and during PCB design may suffer further small changes.

Regards,
Tibi
 

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