 
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
|
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
113.252.88.247
In Reply to: RE: FOR JULI@ users: Removing output pulse trans could reveal more transparent sound! posted by lga775 on June 11, 2010 at 13:39:25
There is a 74HC125 (the SMD 14 pin ic at the bottom near the PCI slot)driving the digital trans. The idea to add a tube buffer, in addition to the 74HC125, does not appear rational to me. To improve sound quality, I recommend the following two options:1. Replace the SMD 74HC125 with a regular size 54HCxxx, a ceramic version which sound much better than regular 74HCxxx, not to mention SMD version. You can further improve SQ/noise by using small batteries to drive this IC, 3-7V only 15 ma.
2. If a tube buffer is to be used - remove the SMC 74HC125. Trace the origin of the SPDIF signal which should originate from the AKM 4xxx next to it. Tx should be fed to the tube buffer. I recall that Pin 16 is the Tx, download data to confirm this.
With regard to the two options, it matters whether you can provide a clear HT and Filament PS as noise is always an issue associated with tube circuit. The distance between the buffer and the signal source is also a concern, two long will do away the of idea of a good buffer. Too short, the tube can't practically be placed near the sound card or inside the case.
As a diyer, I prefer option 1. In this scenario a tube buffer is not necessarily better. The cost for Option 2 is too high: noise, heat, placement issue. Such discrepancies may outweight improvement to SQ.
Edits: 06/14/10Follow Ups:
Wow Jack you are super smart, straight forward and willing to share. You are a gem for this PCAudio thread. Between you and Cics I have hope for humanity. Keep thinking/posting. I just wish you were modding the GA-G31M-S2L.
Just wanna ask here.. I was failed in running digital tube buffer, is that caused the multiplexer? Hmmm... running tube buffer must bypass that chip?
There is a resistor network between the trans and 74HCxxx for impedance matching, about 75 ohm. I suppose you are taking signal from the trans input side. However, this is not an ideal position to take SPDIF signal from, although it should work with your tube. If it does not, there might be a problem with your connection.Download data from the link below. See pin layout at page 3, and SPDIF config at page 22. Find the corresponding pins on the 74HCxxx using a multi-meter. Ideally, Tx to grid of tube and DVSS (digital ground) to tube ground.
The AK4114 already has a digital buffer, the use of 74HCxxx is to buffer the SPDIF trans. and optical output. So if you retain the 74HC and add a tbe buffer after the 74HC, you will have three buffers in series. Too many buffers will result in poor square wave response.
By the way, if I were you I would first try direct output from Ak 4114, where SPDIF signal should be relatively pure and untouched. The 74HCxxx altogether with optical etc should be cut off.
Good luck.
Edits: 06/15/10
Hi Jack
Quote:
"Ideally, Tx to grid of tube and DVSS (digital ground) to tube
ground."
Can we use this direct connection out to the BNC socket? Or need to replace 74HCxxx with 54HCxxx and take the feed from there?
TIA
Hi TIA,
Of course you can. You may also disconnect the 74HCxxx by lifting the corresponding pin off the PCB (add solder, lift pin and suck off solder). In addition, lifting pin 14 (upper last pin near the back metal plate) will disconnect the power supply. As the Ak4xxx already has an internal buffer, adding one more after it may not improve the output waveform, although the property of signal may vary according to the second buffer used. You need to perform listen test to find out which option is better.
A suitable resistor network, such as the ones given on the datasheet, should be used. Thereafter a cap or trans before your BNC.
Good luck. Let us know the result.
Jack
i.) Signal out from the output trans. "Sound is normal"
ii.) Signal without the output trans. (impedence measure was 100ohm!) More revealing)
iii.) Signal with multiplexer bypass with 75ohm resistor to ground. "Very transparent!"
iv. )Signal from TUBE buffered circuit. "This is where magical inspiration take place, similar transparency as without multiplexer but with more liquid. perfectly defined highs, deep and powerful precice bass, huge stage, you can really pinpoint the instruments in a orchestra, different is night and day. Its not upgrade of the sound but like changes entire sound. This is the way for a computer transport to inject musicality like CD transport!
in fact audio note does this.
is this transformer involved here?
Could this explain the good reports of using I2S with JULI@?
I have heard good results of sound that using I2S compare to SPDIF, but it is not meant for a long length.. I will try I2S using CAT7 ethernet cable later and compare the performance.
if u are using the I2S output then, this has nothing to do with the transformer or SPDIF.
I use about 1.4 meters of i2s using 75 ohm teflon coaxial cable. The outer shield of all cables are grounded both ends....juli@ and buf32s. Sounds very transparent.
theob, Happen to see your config of I2S. I think you would benifit more by disconnecting all ground shields at the BUF32 and use a seperate wire for all ground connections. The reason for doing so is to remove capacitive loading of the cables - the inputs at the Buf32 will see much lower capacitance because the shields will not be actually loaded but still perform their shield function.
I think you would benifit more by disconnecting all ground shields at the BUF32 and use a seperate wire for all ground connections.
Hi Jack I understand disconnecting all grounds at buf32s but what does use a separate wire for all ground connections mean? Can you say a little more about this?
After disconnecting all grounds at buf32s, the input could no longer make reference to the ground signal and the card would not work at all. A seperate grounding connection is required, therefore, an indepenent wire is used to link the grounds at both cards(this provides physical connection for the three original ground connections, only one ground wire is required)
Like this.
......................========================================
75R cable = +++++++++++++++++++++++++++++++++++++++++++++(Hot)
......................========================================(Gnd)
Coxial cable grounded at output side. Input ground disconnected.
Coxial Cable
.............==================================================
I2SO/P+++++++++++++++++++++++++++++++++++++++++++++++++++++++BUF32in
I2SGnd====================================================Connect the digital grounds of both cards by another wire:
Ground Wire
I2SGnd--------------------------------------------------BUF32Gnd
Edits: 06/26/10 06/26/10 06/26/10 06/26/10 06/26/10 06/27/10
ok just to make sure I understand ... either disconnect I2S ground at buf32s or juli@ (but not both) then run a separate wire from juli@ ground to buf32s ground. Is that correct?Ok I just tried disconnecting the coax I2S grounds from the Buf32s end and I added a separate wire from juli@ ground to Buf32s ground. Sonically I can't tell yet....need an hour to warm up... but initially it works with a lot more output from Buf32s...sounds louder/stronger.
Edits: 06/27/10
[either disconnect I2S ground at buf32s or juli@ (but not both) then run a separate wire from juli@ ground to buf32s ground. Is that correct?]
No. The correct way is to disconnect I2S ground at buf32s only. If you do it the other way round, the ground shield (now starting at the buf32s) would need to run much longer way (i.e. through the added ground wire) before connecting to the julia@ ground. This is a one-way-only exercise.
[Ok I just tried disconnecting the coax I2S grounds from the Buf32s and I added a separate wire from juli@ ground to Buf32s ground.]
That's correct.
One more thing, the grounding wire/material may affect the speed of signal transfer. This is called "Skin effect" - tendency of an AC current to distribute itself within a conductor so that the current density near the surface of the conductor is greater than that at its core. That is, the electric current tends to flow at the "skin" of the conductor. The skin effect causes the effective resistance of the conductor to increase with the frequency of the current because much of the conductor carries little current. Therefore, a single strand Solid wire will have more resisitance to high frequency AC curent. Multi-strand wires, preferably, silver coated, will usually do better.
[Sonically I can't tell yet....need an hour to warm up... but initially it works with a lot more output from Buf32s...sounds louder/stronger.]
You have got three ground wires in your previous config., this may not create ground loops provided that all the ground shields are connected to the same grounding point on both boards. In your previous config. with three sheilds connected, this may present three times the capacitive loads of a single cable to the I2S inputs. Note that the I2S outputs at the juli@ are not bufferred. Also note that capacitive load would require current to discharge but the same is lacking in the juli@ I2S output.
A new ground wire needs some time to break-in. The sonical difference may be some refinement in accuracy and depth of music, in particular at low level. Hope the alternative gnd connection will improve the SQ.
You said...'A new ground wire needs some time to break-in. The sonical difference may be some refinement in accuracy and depth of music, in particular at low level. Hope the alternative gnd connection will improve the SQ...'
Ok Jack: right on all counts except even more in my system. What I get is better bass and as result more space around instruments, more air. Definitely more depth and a sonic 'rightness' to the sound. I get better integration between highs and mids as mids are tightened up significantly. I ended up rebalancing my crossover points...down .2 db in bass and mids... to further improve my overall balance.
Thanks again for your unsolicited help!!
.
Jack I can't believe the ease with which you diagnosed that I had an excessive capacitance issue then offered a super simple solution. Are you an audio electronics designer if not you should be. What do you do for a living?
hi theob, No. I'm not an audio electronics designer. I'm an amature who has an immensed interest in audio electronics. After more than 30 years of learning and diy, I can master the basics of audio electronics. As a hobby and second job, I once ran a shop where I built tube amps, did modifications for customers and sold vintage tubes. I treat audio electronics as an art and were not making good profits as would a business. Three years ago I closed the shop in order to focus on my first career, I now used it as a workshop cum listening room though.
I learned a lot from the contributions of cics and you guys, and in return, I will try to contribute if I could.
I notice you've rebalanced your crossover levels after implementing the alternative grounding solution. If you're interested and patient, I have an unimaginable story to tell about crossover leveling. A story about the beauty of a 0.01 ohm resisitor on a crossover.
Please do tell the story. For your info in my system I use passive crossover for my high frequencies (I think its a 12 db octave rolloff below 125 hz, it came with the speakers). For the bass I run part of my Buf32s output into a Behringer electronic crossover then from the Behringer directly to my mid bass and subwoofer amps.
Twenty odds years ago, I saw an audio electronics practitioner, who was my tutor, setting up a pair of speakers for a customer. At that time, I already have basic knowledge on setting up speakers and successfully built several pairs of speakers. I saw him using long chains of resistor to level the mid-range and tweeter. The chains of resistor consisted of various values, but strange enough, I found some values as small as 0.01 and 0.05 ohm.
I was curious as to why standard values couldn’t be used. He told me that standard values such as 0.1 ohm was far from ideal for setting up speakers; in order to achieve best accuracy 0.01 ohm was required. He also stressed that when perfect balance was achieved, either adding or removing a 0.01 ohm resistor would spoil the perfection and it would sound distinctly bad upon comparison.
Although he was a very experienced audio practitioner, I was very doubtful about his theory and had a lot of questions. Why I haven’t heard about that before? Why hi-end speakers weren’t built that way? Were human ears so sensitive to be able to distinguish the difference made by a 0.01 ohm resistor (equivalent to a piece of wire) on a tweeter or mid-range?
If what he said about cross-over leveling was true, all cross-over in commercial speakers would be inaccurate because only standard value resistors were used.
Guys, what do you think?
I don't know. What I do know is I want to hear part 2.
I don't know either. Hope there are only two parts so don't have to keep us in suspense!
Hi theob
Congratulation on the new improvement. Any diagram or photo to show your new implementation?
No diagram but I use 75 ohm teflon dielectric coax for each of the I2S lines. I combine the grounds of the coax @ juli@ then tie to one of the ground pins on Juli@. As Per Jack I float the ground ends of the coax at my Buf32s. Then I run a separate line from Juli@ ground to Buf32s ground. Thats it. Fairly simple but highly effective.
Key to using shielded coax is you can use longer I2S lines (mine are over 1.4 meters long). Those who use unshielded I2S lines are always emphatic to recommend very short lines to keep rfi at a minimum.
Thanks for the prompt reply. Yes, I understand the floating shield principle. Is your Buf32 an outboard DAC? How do you apply the 22ohm damping resistor?
Regards
The Twisted Pair Buffalo is a diy outboard dac using 8 ess sabre chips (4 a side in parrallel) to do the work. I soldered the 22 ohm resitors to the juli@ output pins then soldered my coax inner cable to the resistors.
Thanks again Jack. I have a stranded wire as my ground to ground connection. It never ocurred to me that this may require breakin. I'll report back in a few days on sonics.
You are 'the electronics man!...'
I was attempted to implement I2S connection from my Juli@ to my DAC, it was no sound.***J3 Pin 1 -> 1724 PSDOUT[0] ( I2S data out) -> AK4358 SDTI1 (I2S data in)
***J3 Pin 5 -> 1724 PSYNC ( I2S Word Clock ) -> AK4358 LRCK (I2S Left/Right Word clock)
***J3 Pin 7 -> 1724 PBCLK ( I2S bit clock out ) -> AK4358 BICK ( I2S bit clock in )
J3 Pin 9 - > Xilinx on the digital board -> AK4358 MCLK ( I2S Master Clock in )
J3 Pin 11 - > Xilinx & AK4114 on the digital board - > AK4358 PCN (Reset)
Those with asterisk were the signal i tapped and directly feed into my DAC's CS8420 at pin 16,17,18 and both juli@ and dac ground.
I am not sure what was wrong, do i need to connect the master clock and PDN reset as well?
The wordclock was tapped from the J3 P7. It means using the JulI@ as master and dac as slave.
So the connections still remains by using TUBE SPDIF but with external wordclock SYNC.
Wow. I heard some details i never listen before at the same tracks.
The musical effect was so much better and sound is more accurate in tone.
Hmmm, i have some clue that a good cable with I2S connection could make good sound.
Edits: 06/28/10 06/28/10 06/28/10
I'm not sure whether you need master clock. I don't on my Buf32s. I will tell you that I hooked up the signals several times wrong before I got it right. You may want to check if you want to try again. Also I use 22 ohm damping resistors (to match the juli@ impedance). I'm not an expert but it was the resistors that made the thing sonically a success.
i just directly solder the I2S including master clock from juli@ to my dac.. But still couldnt work. Quite a tough effort.
Now enjoying music using TUBE SPDIF + WORDCLOCK sync from juli@.
Much better.
Post a Followup:
| FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
||||||||||||||
This post is made possible by the generous support of people like you and our sponsors:
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2024, Audio Asylum, all rights reserved ]
