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Old 19th March 2008, 11:30 PM   #21
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Default 8412/4 PLL tweaking

The PLL filter for the 8412/4 on the D1 and D1V3 is taken straight from Crystal's datasheet for the 8412. Based on past experience with the 8412 in my old Assemblage DAC 2.0 it's worthwhile applying the "Wildmonkeysects" filter mod.

I was discussing this via email with Skilmek so have cut and pasted the info here:

--

Just checked the schematic for the DIR9001 and see that it has a loop filter on the adapter board. So it seems that applying the wildmonkeysects loop filter will not effect plug and playability.

There were slightly different recommendations for 8412 and 8414:

http://www.audioasylum.com/audio/twe...ges/30313.html

http://www.AudioAsylum.com/audio/twe...ges/44352.html


So component selection depends on which one you plan to use. The components Spencer has listed on the schematic are the datasheet recommendations for the CS8412, while the values for the CS8414 should be slightly different. If you reclock the dac this mod will probably have no impact whatsoever, but without the reclocker it should be worth doing, as parts cost is minimal.

cs8412

replace C200 with 0.22uF
replace R114 with 470R or 500R resistor
add 3300pf cap between FILT (pin 20) and AGND (pin 21) keeping leads as short as possible


cs8414

replace C200 with 0.20uf or 0.22uF
replace R114 with 270R resistor
add 2200pf or 3300pf cap between FILT (pin 20) and AGND (pin 21) keeping leads as short as possible
WMS adds the note "Presuming it locks, I would try different values of the resistor, 220R, 240R, 270R, 300R and stick with the smallest one that sounds good."

So effectively you add one part, soldered directly to the pins of the socket. If you are using an adapter I'd solder the 2200/3300pf cap between the pins on the adapter to get it closer to the chip or if you are brave use a smd cap and try soldering it as close to the pins on the chip as possible.

--

I haven't done the mod on the my D1V3 as yet but will be making the changes after the easter break..

cheers
Paul
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Old 19th March 2008, 11:52 PM   #22
sklimek is offline sklimek  United States
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Default Re: 8412/4 PLL tweaking

Quote:
Originally posted by spzzzzkt

I haven't done the mod on the my D1V3 as yet but will be making the changes after the easter break..

Enjoy your Easter break...
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Old 20th March 2008, 12:22 AM   #23
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Thanks, you too! Four days of camping and bird watching in the Victorian Mallee at Hattah-Kulkyne national park. should be nice...

this is how it sounded one windy morning last september, there is a loud call that clips the recording about half way thru so beware!!:

http://www.mactrix.com.au/files/reco...tah_Edit_2.mp3

fwiw the recording was done with a DIY mic preamp - using a walt jung design with THAT1510 chips as a replacement for the original ssm's.

I'll be trying out a new mic rig this trip so hopefully should get some nice recordings.
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Old 20th March 2008, 03:46 AM   #24
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Default Another D1V3 "tweak": Output Relays

Checking Spencer's schematics vs the D1 service manual I've discovered the D1V3 mute relays have contacts in the signal path , rather than the ground shunt used in the D1 Should be easy to work around, as my old DAC 2.0 had the same type of bypass surgery done on it. Looks like a job for the post holiday tweak session.

Update: Ironically the assembly instructions direct you to cut the pins required to implement the fix off the relays!! If the pins are left on and soldered to the pads - which are grounded, it's a simple matter of cutting the traces between R19,20,30,40 and the relays, then running short jumper wires from the relay side of R19,20,30,40 to the output pads. In normal operation the relay is not connected, but in mute mode the outputs are shunted to ground.


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Old 20th March 2008, 04:30 AM   #25
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Default rewire

Ran out of time to edit the post. I've attached a pic of what needs to be done.
Cut traces on the X. The relay pins that need to be soldered are in the red circles, and the green lines show where the jumpers need to go.

If the pins are already cut on the relay you will need to replace the relays to perform this mod.

While I would not have even contemplated making a DAC like this from scratch without Spencer's boards, I'm finding enough things I would have done differently that I'm now seriously thinking about making my own boards. Gotta love DIY
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Old 20th March 2008, 05:44 AM   #26
spencer is offline spencer  Hong Kong
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Hi,

I have posted the assembly instruction manual and on the page 2 and 3 of first file, there is a more simple way to address this pcb error.

NP D1 DAC clone with enhancement

Spencer
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Old 20th March 2008, 09:19 AM   #27
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Hi Spencer,

The instructions you refer to in the assembly manual leaves relay contacts in the signal path. Which is precisely what you don't want if you are concerned with good sound, and what the original schematic avoids by using a shunt arrangement.

The description in the assembly instructions show the two pins being taped to AVOID being grounded. I'm saying these pins NEED to be grounded, to allow the output to be shunted to ground. The output from the resistors R19,20,30,40 should be wired directly to the outputs, and the traces connecting R19,20,30,40 them to the relay should be cut. In this arrangement there is always a direct connection to the output jacks with no contacts in the signal path. The output is shunted to ground when the mute engages.

cheers
Paul
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Old 20th March 2008, 09:36 AM   #28
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Default And the D1 way...

This how it should be done....

Outputs shunted to GND to mute. No contacts in the signal path. Lovely.
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Old 20th March 2008, 09:37 AM   #29
spencer is offline spencer  Hong Kong
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Paul,

Yes I got your point now. Thanks for the comment.

Spencer
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Old 23rd March 2008, 01:58 AM   #30
sklimek is offline sklimek  United States
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Default Re: rewire

Quote:
Originally posted by spzzzzkt
Cut traces on the X. The relay pins that need to be soldered are in the red circles, and the green lines show where the jumpers need to go.

If the pins are already cut on the relay you will need to replace the relays to perform this mod.

Hi Paul, I decided to take your advice and get the relay out of the signal path. The supplied relays from spencer (Takamisawa relays R5YW-K) are hard to locate. I believe I found a substitute for anyone else interested in this mod and need to secure two more relays if the two pins were cut for your kit; you can get Omrons from Mouser for 2.95 ea.

Here is an attachment if you are interested at looking over the data of both relays and how they match up w/ a Mouser link for the part.

Stan

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