[wackyterbacky]

Your problem may be caused by other software that is running at the same time.

What is your setup on the PC? OS? Music player? Juli@ driver?

I have XP SP3. I use Foobar2000 0.9.6 beta 2 which I run in Realtime priority mode. I use the native Juli@ ASIO 2 drivers. I have a simple batch file that launches Foobar2000

Batch file information. Paste the following into Notepad, make any changes needed, save as YourFilename.bat on your Desktop:

@echo off
c:
cd "Program Files\foobar2000\"
start/realtime foobar2000.exe

Also, I run Juli@ drivers 0.979 which I think are the best for Windows XP.

I turn off all System Sounds in Windows Control Panel:

Start>Settings>Control Panel>Sounds and Audio Devices>Sounds Tab>Sound Scheme>No Sounds

I found that some programs (or websites) play sounds and those come through.

Sometimes just opening web pages will cause enough CPU cycles to hit 100% and that can step on the music player.

There is lots of info here and on audioasylum about PC setup for best sound.

 

[FibCouple]

Quote:

Originally Posted by wackyterbacky /img/forum/go_quote.gif Your problem may be caused by other software that is running at the same time. What is your setup on the PC? OS? Music player? Juli@ driver?

Thanks for your reply. My PC is dedicated music server with cic's mods & running cMP & cPlay (audioasylum pc audio threads) or albumplayer. The cpu cycles at 2% or so & no other programs running. I think I am running 0.978 driver. I remember trying .979 but for some reason Juli@ didnt agree as I had removed the analog board.

This sound a bit like the occasionl crackle I had with adaptive usb interface I tried earlier, I guess when there was data overflow??

Regards

Fib

 

[FibCouple]

Hi wackyterbacky

Could you please tell me which connector you have used for the coax connection to Jui@ pins. If there is a part no. that will be really handy too. Presently I have soldered the wires directly & I am thinking of redoing all connections more securely to see if I can find a reason. Many thanks


Regards

Fib

 

[audioengr]

Quote:

Originally Posted by wackyterbacky /img/forum/go_quote.gif Thanks Steve. I thought I read one of your posts saying the Perpetual DAC sounds better without the case. That is how I am running it now, so I could probe the PCB. Do you have a mechanism for that?

Yes, it is the parasitic capacitance in the Op-amp feedback loops. My mods pretty much eliminated this, but I dont mod the P-3A anymore. In fact, I will not be modding anything starting 2009.

Steve N.

 

[audioengr]

Quote:

Originally Posted by FibCouple /img/forum/go_quote.gif Dear Wackyterbacky Thanks for taking time to put your juli@ mods here as I have been able to tap the i2s for my TDA1541 dac. Dear Steve Thanks for detailing the i2s cabling info and sharing your excellent knowledge here. Could I ask for some help in solving my little problem please. I have i2s signals exiting juli@ to my TDA1541a dac & can get a lock on 16/44. Each signal is going via a star quad cable (Gotham) with 2 wires for signal & 2 for ground. The grounds are tied together in juli@ at vss (pin 5 header 7) & in the dac at analog ground & master clock ground. Overall sound & presentation is amazing. At present I have 390R damping resistors just before the dac (as part of original dac design - Arcam delta 70.2) The problem I am having is a crackling sound every minute or so. The sound remains whether I choose internal reclocking in dac or not. As this is not a continuous crackle, I am not sure it can still be ground or is it a clock/timing issue. Many thanks Regards Fib

Are these 390 ohm resistors to ground or in series with the signals?

Steve N.

 

[FibCouple]

Quote:

Originally Posted by audioengr Are these 390 ohm resistors to ground or in series with the signals? Steve N.

Hi Steve

Thanks for the reply. Yes these resistors are in series with the signals.

Regards

Fib

 

[wackyterbacky]

Quote:

Originally Posted by FibCouple /img/forum/go_quote.gif Could you please tell me which connector you have used for the coax connection to Jui@ pins. If there is a part no. that will be really handy too. Presently I have soldered the wires directly & I am thinking of redoing all connections more securely to see if I can find a reason. Many thanks Fib

I used flat ribbon connectors - 2 rows x 5 positions I think. Standard 0.1 spacing. I don't have a part number, but you can probably find them ( maybe more positions) at Radio Shack. The Juli@ uses similar connectors, but PC mount.

I decided not to solder to the board in case I decided to sell the Juli@ at some point.

 

[audioengr]

Quote:

Originally Posted by FibCouple /img/forum/go_quote.gif Hi Steve Thanks for the reply. Yes these resistors are in series with the signals. Regards Fib

That's really high. Should not be more than maybe 80 ohms with a twisted-pair 110ohm cable. Large series resistors will slow the edge-rate and add jitter. R-C effect.

Steve N.
Empirical Audio

 

[FibCouple]

Quote:

Originally Posted by wackyterbacky /img/forum/go_quote.gif I used flat ribbon connectors - 2 rows x 5 positions I think. Standard 0.1 spacing. I don't have a part number, but you can probably find them ( maybe more positions) at Radio Shack. The Juli@ uses similar connectors, but PC mount. I decided not to solder to the board in case I decided to sell the Juli@ at some point.

Thanks wackyterbacky, I'll look these up in farnell or digikey here in UK.


Quote:

That's really high. Should not be more than maybe 80 ohms with a twisted-pair 110ohm cable. Large series resistors will slow the edge-rate and add jitter. R-C effect. Steve N. Empirical Audio

Thanks Steve. I'll install some 30 ohms as recommended earlier by you. My cable's single conductor's resistance is <83 ohm/km.

Now I have seen in some designs, that these damping resistors are placed at source as well at the dac end on the cable. Would it be enough if I just changed the dac end resistors? Thanks

Regards

Fib

NB: Must say that going back to spdif definitely has lacked detail compared to i2s, even with this crackle, though admittedly I am using rca instead of the bnc connector.

 

[audioengr]

Quote:

Thanks Steve. I'll install some 30 ohms as recommended earlier by you. My cable's single conductor's resistance is <83 ohm/km. Now I have seen in some designs, that these damping resistors are placed at source as well at the dac end on the cable. Would it be enough if I just changed the dac end resistors? Thanks

The resistance of the conductors is entirely different than the characteristic impedance. This is an AC impedance at high-frequency. You are quoting a DC resistance. A twisted-pair of teflon insulated wires is around 100 ohms characteristic impedance. It takes both forward and return path conductors to measure characteristic impedance.

For series termination, which is what we are talking about here, the resistor should be located as close as possible to the source driver, preferable within .1". There should be no resistor at the destination. The output driver impedance plus the resistor should equal the impedance of the cable.

Steve N.
Empirical Audio

 

[FibCouple]

Quote:

Originally Posted by audioengr /img/forum/go_quote.gif The resistance of the conductors is entirely different than the characteristic impedance. This is an AC impedance at high-frequency. You are quoting a DC resistance. A twisted-pair of teflon insulated wires is around 100 ohms characteristic impedance. It takes both forward and return path conductors to measure characteristic impedance. For series termination, which is what we are talking about here, the resistor should be located as close as possible to the source driver, preferable within .1". There should be no resistor at the destination. The output driver impedance plus the resistor should equal the impedance of the cable. Steve N. Empirical Audio

Sorry, yes I was quoting the dc resistance. The cable I am using is a Gotham star quad, with opposite two wires connected together to form either an i2s signal component or its correspoding ground. The wires have PE insulation and the pigtailed conductors become 21awg equivalent. Sorry I havent got a foggiest clue yet how to calculate my ac impedance.

I will email gotham support as well to see if they have the characteristic impedance figure handy.

In all TDA1541a designs I have come across, I always see these resistors right next to data, bck & ws input pins on the dac (ie close to destination) but I understand you are suggesting them at the i2s output chip. Unfortunately, even looking thru the datasheet of Envy1724 (juli@'s i2s output chip) very carefully, I cant find any evidence of output impedance. Maybe wackyterbacky has looked at that figure to calculate the damping resistors?

I really appreciate you taking time to help. Thanks.

Regards

Fib

 

[audioengr]

Quote:

Originally Posted by FibCouple /img/forum/go_quote.gif Sorry, yes I was quoting the dc resistance. The cable I am using is a Gotham star quad, with opposite two wires connected together to form either an i2s signal component or its correspoding ground. The wires have PE insulation and the pigtailed conductors become 21awg equivalent. Sorry I havent got a foggiest clue yet how to calculate my ac impedance. I will email gotham support as well to see if they have the characteristic impedance figure handy. In all TDA1541a designs I have come across, I always see these resistors right next to data, bck & ws input pins on the dac (ie close to destination) but I understand you are suggesting them at the i2s output chip. Unfortunately, even looking thru the datasheet of Envy1724 (juli@'s i2s output chip) very carefully, I cant find any evidence of output impedance. Maybe wackyterbacky has looked at that figure to calculate the damping resistors? I really appreciate you taking time to help. Thanks. Regards Fib

Characteristic impedance is usually only specified for impedance-controlled cables.

Just because you see something done repeatedly in designs does not make it correct. There is a lot of blind leading the blind in this industry IME.

Steve N.

 

[FibCouple]

Quote:

Originally Posted by audioengr /img/forum/go_quote.gif Just because you see something done repeatedly in designs does not make it correct. There is a lot of blind leading the blind in this industry IME. Steve N.

Fair comment. I wouldnt know where I have been led except by reading up articles/posts from people more clever than me as re electronics.

My presumption was that resistor close to entry into dac were damping resistors but what do I know

Anyway, now a 110 ohm impedance starquad cable is going in with flat cable connector as used by wackyterbacky. As I dont know the exact i2s output impedance for envy1724, I am going to use 30 ohm resistors close to julie i2s out. I'll keep everbody posted. Thanks for the comments.

Regards

Fib

 

[nopietns]

Now I can confirm that the North Star Design M192 DAC locks to the I2S signal of the Esi Juli@ and the sound is quite sweet. Haven't had any problems (apart from that ESI cards don't like nVidia chipsets and have problems playing higher samplerate and bit files)

Attached an image of my temporary test cable, which is the cheapest RJ45 from the nearest supermarket. I haven't spent time comparing to the sound from SPDIF signal, though.

Many thanks for answers to my questions, mostly to audioengr and wackyterbacky.

 

[audioengr]

Quote:

Originally Posted by nopietns /img/forum/go_quote.gif Now I can confirm that the North Star Design M192 DAC locks to the I2S signal of the Esi Juli@ and the sound is quite sweet. Haven't had any problems (apart from that ESI cards don't like nVidia chipsets and have problems playing higher samplerate and bit files) Attached an image of my temporary test cable, which is the cheapest RJ45 from the nearest supermarket. I haven't spent time comparing to the sound from SPDIF signal, though. Many thanks for answers to my questions, mostly to audioengr and wackyterbacky.

Very welcome. Most of my customers are now getting the Revelation Audio Labs Silver-cryo reference I2S cable. This one really makes a difference, even if it's longer.

Steve N.