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Old 23rd March 2008, 03:26 AM   #31
sklimek is offline sklimek  United States
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Corrected link for the Takamisawa RY5W-K data sheet:

http://www.fujitsu.com/us/services/e...s_ry-5w-k.html
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Old 23rd March 2008, 04:20 AM   #32
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There's the Nais/panasonic too:


http://www.relays-r-us.co.uk/webpage...cat_index.htm#

look at the 'DS' (2e)series.
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Old 24th March 2008, 01:08 AM   #33
sklimek is offline sklimek  United States
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Quote:
Originally posted by mpmarino
There's the Nais/panasonic too:


http://www.relays-r-us.co.uk/webpage...cat_index.htm#

look at the 'DS' (2e)series.
Hi Marc, looks like the Nais 5V DS2E should work quite nicely.

Where are you finding them???

Stan
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Old 24th March 2008, 02:46 AM   #34
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Quote:
Where are you finding them???
I don't know where you'd buy them (I never looked for a source).

edit: I'm a junkyard dog...
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Old 25th March 2008, 05:18 AM   #35
sklimek is offline sklimek  United States
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Hi Paul,

When you mentioned:

“For instance I discovered that the transistors for the mute relays aren't shown in his pics, nor mentioned in the notes but the outputs are muted unless they are installed”.

Are your referring to the 2SJ148 and the 2SK982? And if so are the IRF mosfets (9610 and 610) that are parallel just another option if you don’t go w/ the 2SJ148 and 2SK982???

Stan
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Old 25th March 2008, 09:27 AM   #36
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Hi Stan,

Yes Q49,50,51,52. The parallel transistors do seem to represent an either/or option - I used the IRF's because I had a small pile of them and they work fine.

Thanks for the heads up on the DS2E relay option. Was able to find the panasonics at a local surplus parts supplier. Also ordered a handful of 8TQ100 schottky rectifiers to upgrade the PSU's.

cheers
Paul
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Old 26th March 2008, 11:13 PM   #37
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Relay Mod
Output relay mod is done. Apart from a minor "foxes paw"* of connecting + of right channel to gnd and wondering why I had a what sounded like a major ground loop the procedure was straight forward and as described.

It is easiest to jumper from relay side of the output resistors to the output connector pads. I also changed the digital rectifiers to 8TQ100 schottky so not sure what mod contributed what. There seems to be a minor improvement to the precision of imaging, which is similar to the results I got performing the same mod on the DAC2.0. The improvement isn't earth shattering, but still worthwhile I think.

Reclocker
It seems the bias voltage applied to the PPL loop in the original D1 is partly required bias the Fujitsu Lithium Tantalate VCXO used to closer to the middle of it's pull range. I pretty sure this will not be required when using the Tent Labs VCXO.





*faux pas
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Old 27th March 2008, 07:11 PM   #38
sklimek is offline sklimek  United States
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I received two more than I need of the 5V DS2E relays needed (courtesy of mpmarino) to do the relay mod that Paul outlined. If anyone needs these shoot me an email and I’ll send them to you on my nickel…

Stan
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Old 30th March 2008, 08:50 AM   #39
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Default DAC analog regulator mods

Just done a nice mod on the DAC analog regulators based on those described on Martin Clark's pages:

http://www.acoustica.org.uk/t/3pin_reg_notes1.html

I've replaced the each of the 300R resistors R105,109,126,127 with a unit made up of 2 parallel 3.3V zeners and a 1N4148 diode. With the 100R resistor Spencer uses this is pushing the limits giving 5.3-5.4V, tho' this is still within the supply specs from the PCM63. Probably better to change the 100R to 120R or use 3V zeners to give an output closer to 5V.

If you try this make sure you pull the DAC chips and verify the voltages are within spec. I hooked up the negative unit incorrectly and had -17.5V on pin 28, which would have definitely killed the DAC if it had been left in place!!!

I've nabbed the correct diode orientation from this pdf:
http://www.diyaudio.com/forums/attac...amp=1168083193

I haven't implemented the 10uF (or bigger) cap from adj to gnd yet. This is on the to do list.

The result of the mod should be a quieter analog supply to the DAC, which seem to have clean things up slightly. It's hard to be certain as I can't A/B the changes but I seem to be getting slightly better detail and sharper imaging. Instruments stand out from the background a little better than previously using my reference recording - Miles Davis' "Bitches Brew". "Spanish Key" is definitely sounding better than I've heard it before.


I'm also thinking about doing the same mod on the digital supplies, and replacing the LT1117 regs with LM340-T5 smd regs. The LT's have far worse ripple rejection and output noise specs than the lowly 340's so this seems like a no brainer but a little fiddly as a replacement job!!

cheers
Paul
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Old 30th March 2008, 09:06 AM   #40
Dave is offline Dave  New Zealand
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Spencer,

I think the 47uH inductors you have inline with the PCM63 supply rails might be a concern. These will form a resonant circuit with the 47uF capacitors, resonant frequency will be 3.386kHz right in the audio band.
The characteristic impedance is 1 ohm so the DC resistance of the inductor and/or ESR of the cap might be enough to damp it properly but could be worth double checking.

Dave
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