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Ultimate Twin TDA1541a Non-oversampling DAC with tube buffer & reclock set.......

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#543
Grounding v2 Dac

Ping Quan Tran, Julien, Shane, Thomas

Need some help figuring out ground plan for v2 dac. I'm only using Dac pcb and Tube buffer pcb. Several Qs:

1. Am I correct in thinking that the wires that run between Dac output pcb and Tube input pcb do NOT ground digital and analog pcbs together because Dac output terminals are NOT on Digital ground plane?

2. I see the Gnd terminal on both the Dac pcb and tube pcb (middle of both boards). Most of the pics of finished dacs posted to this thread do NOT have ground wires running from these Gnd terminals to chassis. Unless the wires run underneath the pcb's? By NOT running ground wires from these terminals to chassis, does this mean that the dac pcb and tube pcb are "floating"?

3. Is it simply trial and error to see whether grounding these pcbs results in lower or higher hum? If grounded, should one tie the ground wire from the dac pcb to the same place on the chassis as the gnd wire from the tube pcb? If so, where on chassis?

4. RCA Digital Input. What is best way to install this. I plan to use shielded twisted pair. Does a separate gnd wire need to run from this jack to chassis ground? Should/must I solder 75ohm resistor at rca female jack mounted to chassis? Should this rca contact metal chassis or use use insulated rca jack?

5. RCA Analog Output. Same Q. Does a resistor or cap need to be soldered anywhere at the female rca jack? Does a ground wire need to run from chassis to jack...other than twisted pair?

6. Transformer ground wires. Plan to gather all black ground wires from 3 transformers and terminate at chassis ground at one point. For primaries, if these wires aren't long enough to run all the way to iec input, should I use an insulated copper terminal so that I can run 12awg ac wire from terminal to iec input?

7. If I install a power on switch on the front chassis...opposite the iec input on back chassis, is it better to locate this along/near the tube pcb or the dac pcb?

Thanks very much for any feedback. Sorry for the long post. Your feedback is greatly appreciated.



:smash:
 
#544
Re: Grounding v2 Dac

riotubes said:

1. Am I correct in thinking that the wires that run between Dac output pcb and Tube input pcb do NOT ground digital and analog pcbs together because Dac output terminals are NOT on Digital ground plane?
Click to expand...

I think all the ground pins are connected at some point. I am not sure where.


riotubes said:

2. I see the Gnd terminal on both the Dac pcb and tube pcb (middle of both boards). Most of the pics of finished dacs posted to this thread do NOT have ground wires running from these Gnd terminals to chassis. Unless the wires run underneath the pcb's? By NOT running ground wires from these terminals to chassis, does this mean that the dac pcb and tube pcb are "floating"?
Click to expand...
Yes, my board are floating.


riotubes said:

3. Is it simply trial and error to see whether grounding these pcbs results in lower or higher hum? If grounded, should one tie the ground wire from the dac pcb to the same place on the chassis as the gnd wire from the tube pcb? If so, where on chassis?
Click to expand...
You could try it but I don't think there will be audible difference.

riotubes said:

4. RCA Digital Input. What is best way to install this. I plan to use shielded twisted pair. Does a separate gnd wire need to run from this jack to chassis ground? Should/must I solder 75ohm resistor at rca female jack mounted to chassis? Should this rca contact metal chassis or use use insulated rca jack?
Click to expand...
This is quite tricky due to the lay out. I could not manage to implement a true 75 ohm connection event I have installed a BNC terminal. There is only one way to do it i.e. connect coax cable directly to to PCB and avoid any connection terminal. I don't want to do it because, again, I think there will not be significant audible difference.

Note that the 75ohm resistor is at the secondary winding of the pulse trans.

riotubes said:

5. RCA Analog Output. Same Q. Does a resistor or cap need to be soldered anywhere at the female rca jack? Does a ground wire need to run from chassis to jack...other than twisted pair?
Click to expand...
There is no need for any caps or resistors.
As I mentioned above there is only one way for true 75 ohm.

riotubes said:

6. Transformer ground wires. Plan to gather all black ground wires from 3 transformers and terminate at chassis ground at one point. For primaries, if these wires aren't long enough to run all the way to iec input, should I use an insulated copper terminal so that I can run 12awg ac wire from terminal to iec input?
Click to expand...
I think, this will be perfectly OK.

riotubes said:

7. If I install a power on switch on the front chassis...opposite the iec input on back chassis, is it better to locate this along/near the tube pcb or the dac pcb?
Click to expand...
I think the tube board is more prone to hum from the power line than the DAC board. DAC board is affected more by HF noise from some where also.
 
#545
Quan Tran, Thank you for your prompt and thorough reply. I really appreciate your help. As a novice diy'r, I became a little overwhelmed reading about digital grounding strategies, particularly since there appears more than one way to go about it. Thanks
 
#546
Yes, grounding is quite tricky. If not done properly it will be much worse than floating.

if you would like to try you could ground one single point of either board.

If the electricity system at your house has no earth connection, I think grounding to the chassis is useless.

There are other things that make much more significant improvement in sound than grounding.
 
#548
Hello, some enquiries!

Hello Thomas,

I am considering picking up one of your v.3 kits, but before I proceed, I have a few questions:

1. There are over 500 posts in this thread alone - I'm very sorry, but I only skimmed through al of them. Does this DAC kit:

a. come with instructions on construction
b. come as a full kit (i.e. all I need is a soldering iron, multimeter and nothing else?)

2. Is it possible to replace the TDA1541A chips with S2 versions from your other groupbuy? How much extra?

3. I will be streaming digital in via SPDIF from a computer-based rig - what are the capabilities of the reclocking circuit to handle the (probable) mich higher jitter from my source? Does anyone know of any way to reduce the jitter before my digital bitstream enters the DAC?

You can email me at <oh.aaron@yahoo.com.au>

Cheers! 🙂
 
#549
Adhoc,

If you are going to feed the dac with pc music server, use a usb input and convert to i2s (instead of spdif). If the v3 dac board has i2s solder pins on the pcb (like the v2 board) then one quick way to accomplish this is to do like Shane did and buy Doede's usb-i2s board (ddac.de) and install it in your dac chassis, and run wires from i2s out on this board to the dac board i2s input. You have to desolder a few resistors to make this work. Here's a pic that Shane posted to this board of his tda1541 dac with i2s daughterboard:

http://home.iprimus.com.au/sceglar/250306 012.jpg

For a discussion on how to do this, see this post:

http://db.audioasylum.com/cgi/m.mpl?forum=pcaudio&n=10335&highlight=shane+riotubes&r=&session=
 
#550
riotubes, thanks for that information.

So basically, Doede's usb-i2s board takes a usb signal, reclocks it and sends it out via i2s?

Also, I find no (obvious) mention in the linkage you provided of desoldering various resistors to make this solution work.

I am really confused about this concept of 'reclocking' digital signals; I am not sure whether Doede's board provides this or whether I need it. My understanding is that reclocking reduces jitter?

My apologies - I am an old hand at fiddling around with tubed equipment, but all this digital stuff is going way over my head! :dead:
 
#551
Adhoc,

I was not familiar with Thomas's v3 dac design, but was just reviewing this thread and learned that Thomas's v3 version offers a usb input. I'm sure he designed it so that it is usb-i2s. So, he has made it easy for you. In my case, I have v2 so I need to add a usb-i2s daughterboard and remove R16 and R19 on the pcb to defeat power to the CS8414 spdif receiver when implementing a usb interface.

I am by no means experienced in digital design, but can point you to John Swenson's post on audioasylum if you are interested in learning about the merits of employing a usb-to-i2s interface for your dac (keyword "2706" on PC Audio forum). Just as the cs8412/14 receiver chip (used on v2 of Thomas's dac) accepts spdif input and passes the signal on to the tda1541 dac chip, likewise, the philips pcm2706/7 chip receives usb input, and routes the signal via i2s to the tda1541 dac chip. If you are interested in pc audio, you might as well go i2s the whole way--particularly since the 1541 chip accepts i2s--and cut spdif out of the chain. Jitter exists due to many factors, and there are some ways to reduce it. A reclocking circuit and i2s transmission can reduce jitter.
 
#552
riotubes,

Thanks for that reply.

I have gone back and read the past 100 posts, and now have a much better idea of what's happening. 🙂

Thomas, have sent you an email. Email is from "A. Oh". Please let me know the outcome.

Thanks! 🙂

PS: can someone tell me how to get out of moderation? it's extremely frustrating, being unable to PM or email anyone through the board.
 
#554
Chips groups buy for john's(ECdesign) ultimate 1541a & 1543 DAC

hi all,

This new thread for cheap groups's buy.

for easy management, every transaction will USD 50 & 100.

I thought many diyers was interested for john's ultimate design.

John's design almost the most complicated & he paid much effort for them. But TDA1541a & 1543 was stop production long time.
I paid mch effort on taiwan & found some 1541a & 1543,PCM56 remain in the big store.

For my personal use, I order 1K pcs of PCM56 for the coming parallel 32 pcs PCM56 DAC, Looks was similar to audionote Kondo early period design but was famous. Hope will be another product such as 1541a which was easy accept in diy markets, Mainly was all my design was GOOD Prcie/cost rati😵therwise diyers will not benefit to most diyers.

John's design do the same too, I hope I can use my resource to assitance all the diyers which LOVE his design.

John, now U not need to worry for your project, U can print more PCB if U like to sell the PCB only to lower the basic cost. Hope this cheap groups buy can good support for you.

I check the taiwan's store already.

I can offer TDA1541a USD10 per chip with IC sockets..

so for john's design.

one pc of CS-8414-CS or CS8412-IS.
8 pcs TDA1541a with IC sockets.
Include postage & paypal chage.
USD 100 only.

I will se reg.mail post to ordered diyers.

TDA1543a EVERY 8 pcs USD 10. All with IC sockets
so means 32pcs TDA1543 + CS-8412-IS or CS8414 ( all with Gold pns & adapter)

USD50 include posatge, paypal charge, post method was use air reg.mail.

All chips i will try to match same date code.

AD1865 & PCM63 will coming later.

pls let me know how many diyers had interest.


thx

thomas
 
#555
Hi Thomas 🙂

I'm interested!
But please note that CS8414/12 receivers are no longer used in ecdesigns' project as far as I know: he uses now direct I2S signal from transport.

Could you offer the TDA DAC chips package alone, without the receiver chip?
I'm sure other DIYers will ask for the compo anyway, but it's a 20 dollar save...

I will need:
* 8 TDA1541A.
*32 TDA1543.

Thanks for your constant support to fellow DIYers 🙂

Regards
M
 
#556
hi max,

sorry I hadn't fully read all the detail of john's dac.

exclude the 1541a & 1543 chips any more parts I can asistance john's design???

yes, your order will confirm, can I open another thread for only this several types of chips groups buy, when U compare my price, U will know almost no profit, I like to assiatance john's project already.

Do U advise I open a new one on groups buy or another loaction.

pls advise. My large lot of chips will arrived this frieday.

I will match for them & prepare for U.

not need to pay money first.

I will inform U later.

thx

thomas
 
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