hi i know this is a bit off topic at the moment, but ive been lurking in the background whilst deciding on how to mod my cd67 which a got for a great price 12 pounds in full working order just a little rust on the back plate which was taken care of with white spirit and a lot of elbow greace.
anyway my question is that i want to build a completly separate power supply for it how many trannys will i need at what voltage out do they need to be and waht va rating would you recommend
any help would be greatly appreciated
anyway my question is that i want to build a completly separate power supply for it how many trannys will i need at what voltage out do they need to be and waht va rating would you recommend
any help would be greatly appreciated
reddish75 said:
Hi,
I'm heading in this direction too. So far I have the following:
Transformer #1: clock supplies
winding #1: 'superclock' feed
winding #2: servo clock divider feed (not needed in CD67)
Transformer #2: digital supplies
winding #1: DAC and decoder digital pins
winding #2: DAC clock reference pin
Transformer #3: analogue supplies
winding 1 (centre-tapped tx.): DAC and decoder analogue
That is the situation at the moment. It sounds superb. I will be adding a further transformer (number 4) just for the servo (one winding analogue, one digital).
The internal transformer will keep powering the op-amps in mine (it's a KI so has a good transformer).
You might like to use a separate, dedicated power supply with it's own transformer for the +/-12v.
Every voltage rail used for audio (every one bar the logic chip basically) should be fed by a low noise regulator. This will allow the full, sweet, natural detail to come through. The sound will not be digital in the slightest. You'll need the other mods too of course (reclocking, op-amps etc.)
To go external you'll need an "umbelical" cord to connect things up. I can recommend the use of DIN plugs. Get nice ones of course. If you want to go mental why not use one cable for analogue psus, and a second for digital? This will be easier to solder up too, if that's an issue.
Simon
Attachments
As for VA and voltages, just make the voltages sensible and the VA macho-high. It's generally considered that high VA transformers sound better.
Most of the voltage rails are 5v - dac, decoder, servo. So for these I'd recommend transformers that will provide roughly 10vac or a touch under. This will provide plenty of headroom for regulators to work with.
For the 12v + and - you will obviously need a slightly higher voltage, like 17vac.
Just bear in mind you will need about 3 volts minimum overhead for the regulators to regulate properly. And most regulators will take 30 to 35 volts input.
Use schottky or HEXFRED diodes.
Simon
Most of the voltage rails are 5v - dac, decoder, servo. So for these I'd recommend transformers that will provide roughly 10vac or a touch under. This will provide plenty of headroom for regulators to work with.
For the 12v + and - you will obviously need a slightly higher voltage, like 17vac.
Just bear in mind you will need about 3 volts minimum overhead for the regulators to regulate properly. And most regulators will take 30 to 35 volts input.
Use schottky or HEXFRED diodes.
Simon
Another thing to bear in mind is the transformer type. It is often said the best sounding are R-core. If you have the cash to splash give them a whirl! If on a tight budget you could use E/I core for the digital, as less high frequency noise passes through than with a toroid. Also some people are generally against toroids for hi-fi, saying they sound lifeless and clinical. Don't use old E/I cores unless you don't mind some mechanical hummmm!
Simon
Simon
Hi guys I got some samples of these ultra low esr capacitors in the mail the other day and I was wondering if they would be any good to use in my cd67. They are 470/16v so they would be a nice size to use for the DAC or opamps. I know I read someplace that ultra low esr isnt always a good thing. What do you guys think?
imperfectcircle said:
Go ahead. Someone has done the experiment, but do try it yourself. Let's hear your result.
http://www.diyaudio.com/forums/showthread.php?postid=1041995#post1041995
http://www.diyaudio.com/forums/showthread.php?postid=1042192#post1042192
Well the caps I have are much lower esp than the Panasonic FC, so they proably wont sound very good for the analog sections. Ill stick to Silmic, Cerafine, Muse or BG for analog. Now ive heard good things about Rubycon ZL and Oscons for digital decoupling, maybe these caps I have would work well for digital? They are lower esr then even Rubycon ZL/ZA, Ive heard they are omong the lowest esr cap you can buy. Very popular among computer overclockers to get better stability at high freq. But never tried them in digital audio.
Hi Guys,
I'm back to annoy you.
I'm about to order a number of Black Gate caps for replacements and also to build the reg board below. I've modified Brent's diagram posted earlier.
Since the recommendation is to draw power for the board from C803, I realised I would need some preregulation if I was going to use 16V caps. I've chosen 14V to give enough juice for the 12V regs but not go to close to the 16V max for the caps.
I'm going to be running the following regs on this board:
DAC 5V (analogue)
DAC 5V (digital)
DAC 5V (clock)
Decoder 5V (digital)
Decoder 5V (analogue)
Trichord Clock 12V
2 x Opamps 12V - hopefully placed close to the opamps
Question time:
I figured I'll need a capacitor after the 14V prereg. Have I hooked it up correctly in this diagram? Is it big enough or can I use a smaller value?
What type of caps would be suitable for C3 & C4 and what values?
Thanks again for your help,
Simon
I'm back to annoy you.
I'm about to order a number of Black Gate caps for replacements and also to build the reg board below. I've modified Brent's diagram posted earlier.
Since the recommendation is to draw power for the board from C803, I realised I would need some preregulation if I was going to use 16V caps. I've chosen 14V to give enough juice for the 12V regs but not go to close to the 16V max for the caps.
I'm going to be running the following regs on this board:
DAC 5V (analogue)
DAC 5V (digital)
DAC 5V (clock)
Decoder 5V (digital)
Decoder 5V (analogue)
Trichord Clock 12V
2 x Opamps 12V - hopefully placed close to the opamps
Question time:
I figured I'll need a capacitor after the 14V prereg. Have I hooked it up correctly in this diagram? Is it big enough or can I use a smaller value?
What type of caps would be suitable for C3 & C4 and what values?
Thanks again for your help,
Simon
Gooch said:
Are we talking commercial disks or CD-R / CD-RW ??
When I had my shop, some years ago, A cd-player came in that would only play 2 cds out of 50 or so around. Both were Eric Clapton - obviously a player with taste !
Andy
EDIT :- I could not fix it and eventually sold it to a Japanese student for a fiver with a full fault description. He never complained or came back!
poynton said:
But isn't 18v a little close to ~20v in the latter scenario? Perhaps he should preregulate at just under 16v and just let the caps run close to tolerance - they're expensive and not delivering much current, surely they won't mind it.
Also, might it be wise to NOT take the voltage for the clock, op-amps and everything else from this one supply?
Perhaps the clock and op-amps should take their voltages from different places. I'd suggest a dedicated transformer is used to power the clock. It need only be very small.
Do you think you can manage to knock up a small power supply for the clock, Simon?
Simon (lol)