a333bt said:
sorry,
correct foil, what i using (not aluminium) is:
http://products3.3m.com/catalog/us/...trical_3_0/command_AbcPageHandler/output_html
regards, Bostjan
Hi maxlorenz,
No problem.
I did feel that sometimes many people are assumed to be armchair critics. So, I figured a comment might be helpful. Anything that has someone pick up a soldering iron and build something is good.
Listening tests are very good, but humans are easily fooled. To stay on track, some measurements are helpful. By the same token we need listening tests to keep our measurements on track. The two exist together.
-Chris
No problem.
I did feel that sometimes many people are assumed to be armchair critics. So, I figured a comment might be helpful. Anything that has someone pick up a soldering iron and build something is good.
Listening tests are very good, but humans are easily fooled. To stay on track, some measurements are helpful. By the same token we need listening tests to keep our measurements on track. The two exist together.
-Chris
John,
Examining your diagram in post 1700, I beleive there is an error there.
Connections to vcc and ground should be reversed on J1, pins 1 and 2. Two things could be done. First, labels on pin 1 and 2 could be swaped, or if you want to maintain concordance with J2 vcc should go to pin 1 and ground to pin 2 of J1.
Hope this help.
Jean-Charles
Examining your diagram in post 1700, I beleive there is an error there.
Connections to vcc and ground should be reversed on J1, pins 1 and 2. Two things could be done. First, labels on pin 1 and 2 could be swaped, or if you want to maintain concordance with J2 vcc should go to pin 1 and ground to pin 2 of J1.
Hope this help.
Jean-Charles
Hi JonHarrison,
I used very thin copper tape (approx. 0.05mm)
The Keratherm-Ferrite F96 tape could work too as it's designed for electromagnetic shielding.
Shields usually need to be connected to ground, but when I did this with the copper tape around chips in the USBDI2S module, the interference measured with the oscilloscope got worse, and jitter slightly increased.
I still have to do some tests by connecting the copper foil to chassis instead of GND.
I used very thin copper tape (approx. 0.05mm)
The Keratherm-Ferrite F96 tape could work too as it's designed for electromagnetic shielding.
Shields usually need to be connected to ground, but when I did this with the copper tape around chips in the USBDI2S module, the interference measured with the oscilloscope got worse, and jitter slightly increased.
I still have to do some tests by connecting the copper foil to chassis instead of GND.
Hi a333bt,
I basically noticed that the sound was more relaxing, I am not sure if it's just cause by reduced jitter or reduced crosstalk between the chips, resulting in slightly better signal to noise ratio.
I measured most significant jitter decrease (with external EMI source) after putting copper foil on both 74F164 chips, and 74HC161.
I got best results so far (lowest jitter) when the foils were not connected to GND, however I didn't test connection to frame yet (requires some modifications on the PCBs).
I basically noticed that the sound was more relaxing, I am not sure if it's just cause by reduced jitter or reduced crosstalk between the chips, resulting in slightly better signal to noise ratio.
I measured most significant jitter decrease (with external EMI source) after putting copper foil on both 74F164 chips, and 74HC161.
I got best results so far (lowest jitter) when the foils were not connected to GND, however I didn't test connection to frame yet (requires some modifications on the PCBs).
Hi maxlorenz,
Electrolytic capacitors already have an aluminum housing, so I think putting copper foil on these only has a cosmetic effect.
But I use large size input (foil) capacitors in the MPA80 power amps, these can pick-up both hum and noise. So placing a shield around these and connect the shield to ground should make the input less sensitive. I will give that a try.
by the way, are you already using the low jitter 48 MHz oscillator?
Electrolytic capacitors already have an aluminum housing, so I think putting copper foil on these only has a cosmetic effect.
But I use large size input (foil) capacitors in the MPA80 power amps, these can pick-up both hum and noise. So placing a shield around these and connect the shield to ground should make the input less sensitive. I will give that a try.
by the way, are you already using the low jitter 48 MHz oscillator?
Hi,
The foil providing a path to inject noise into the ground plane perhaps? It would be interesting to see what happens if you connect the foil to the chassis although I'm not quite sure how you'd do this and achieve a low impedance path. If as you suggest some of the RF is turning to heat in the foil I would expect better results with the ferrite tape.
It's all good fun isn't it !
Cheers,
Jon
The foil providing a path to inject noise into the ground plane perhaps? It would be interesting to see what happens if you connect the foil to the chassis although I'm not quite sure how you'd do this and achieve a low impedance path. If as you suggest some of the RF is turning to heat in the foil I would expect better results with the ferrite tape.
It's all good fun isn't it !
Cheers,
Jon
Hi rfbrw,
About post #1714,
I see you switched to hat-making. Although meant as a joke, EMI protective clothing is already being sold for industrial applications,
Take a look at this
http://www.egis-protection.com/index_en.html
About post #1714,
I see you switched to hat-making. Although meant as a joke, EMI protective clothing is already being sold for industrial applications,
Take a look at this
http://www.egis-protection.com/index_en.html
The low jitter or the ultra low jitter?
I'm using the stock item.
Form my audiophile days, I have used this:
http://72.14.209.104/search?q=cache...eet&hl=es&ct=clnk&cd=1&gl=cl&client=firefox-a[/url]
...in very tinny pieces in other projects, not always with sound improvement. Sometimes the sound becomes slower, less defined.
I could try it...after the copper foil jacket
Cheers,
M
PS: are you considering selling the heatsink blocks for the tower cooling?
Thanks -EC- 
My little hometown lacks a decent radio station, so I use to listen only CD's (and LP's every now and then). Not any more
Netradio's are not at all bad (and will improve surely with time).
I had a jam session the other night with DI8*4 playing on the big active system, listening to http://www.dr.dk/netradio/
from which my preferred are DR P2 Klassisk, DR Jazz and DR World (still XP; not Ubuntu yet...drivers...). DR jazz has the best sound and you may know (and if you don't, I tell you) that my Autographs speakers paint a big scale soundstage with big dynamics and with lots of midbass energy ( which is an attribute of "live music" but which is seldom heard on "audiophile" systems)... but not boom-boom bass/midbass but and articulated and punchy reproduction of live instruments like being at Birdland (NY) or something like that.
Sorry for that but I had to say it.
Cheers,
M
My little hometown lacks a decent radio station, so I use to listen only CD's (and LP's every now and then). Not any more
Netradio's are not at all bad (and will improve surely with time).
I had a jam session the other night with DI8*4 playing on the big active system, listening to http://www.dr.dk/netradio/
from which my preferred are DR P2 Klassisk, DR Jazz and DR World (still XP; not Ubuntu yet...drivers...). DR jazz has the best sound and you may know (and if you don't, I tell you) that my Autographs speakers paint a big scale soundstage with big dynamics and with lots of midbass energy ( which is an attribute of "live music" but which is seldom heard on "audiophile" systems)... but not boom-boom bass/midbass but and articulated and punchy reproduction of live instruments
like being at Birdland (NY) or something like that.Sorry for that
but I had to say it.Cheers,
M
-ecdesigns-
wow, looks like an amazing project! I am looking for a project that involves a NOS DAC that I can use with Nelson Pass's D1 I/V stage that will also allow me to use the i2s output directly from a transport as input. After much looking, I've stumbled upon your projects. Wow, looks amazing. From your design, I do not understand why you only offer RCA outputs, isn't this more-or-less a fully balanced design? How does one choose between your two projects?
wow, looks like an amazing project! I am looking for a project that involves a NOS DAC that I can use with Nelson Pass's D1 I/V stage that will also allow me to use the i2s output directly from a transport as input. After much looking, I've stumbled upon your projects. Wow, looks amazing. From your design, I do not understand why you only offer RCA outputs, isn't this more-or-less a fully balanced design? How does one choose between your two projects?
Hi luvdunhill,
Seems my previous post ended up at the wrong thread, so I repost it
DI DACs need Philips format I2S 64 BCK / WS in order for the timing module to interpolate correctly, if your I2S source has a different format, conversion is needed. Easiest way is the use of a SPDIF audio receiver, followed by a shiftregister reclocker (SPDIFDI2S module).
DI DACs interpolate, so they create higher initial resolution when compared to NOS DACs. Interpolation is divided over two DAC groups, one inverted, one non-inverted group. The balanced design reduces common errors, improves CMMR, and most important, provides a DC
coupled output (no added distortion by coupling cap or transformer). Two I/V converters / channel are needed, these converters need to have excellent tracking (same gain / linearity), accuracy needs to be at least 0.1% or better. The DI 8M uses 0.01% bulk metal foil precision resistors to achieve optimal tracking. If gain / linearity differs in both I/V stages, additional bit errors are introduced.
The interpolation results in a slow rolloff filter that attenuates HF images enough to prevent problems in the rest of the audio equipment. Attenuation is sufficient to leave-out the analog filter, enabling excellent phase accuracy.
I can't guarantee optimal DI DAC performance when different I/V circuits are used. The current LM4562 class A I/V converters with bulk metal foil feedback resistors are extremely accurate, high linearity, very low THD, low DC offset voltage, and fast response. This is very difficult to achieve with any kind of discrete circuit, especially when two virtually identical I/V stages are needed.
If a balanced output is required, the diff amp can be left out, and both I/V converter outputs can be connected to a XLR output. The following amplifier with balanced input will then replace the diff amp stage in the DI DAC. However, when that amplifier isn't accurate enough (amplitude / linearity difference between inverted and non-inverted input), bit errors are introduced, degrading sound quality.
I use higher amplitude output signals (2V RMS), and short semi-balanced Litz wire interlinks. My MPA80 power amps have a gain of only 20x. This combination also produces higher resolution at low volume settings. Noise / hum levels are extremely low / inaudible, even when listening a few inches away from the speaker chassis with no signal applied. XLR interlinks are useful when using longer interlinks, but these longer interlinks could also degrade sound quality (capacitance). Another advantage of the RCA outputs is that the diff amp is located very close to the I/V converters.
Noise / hum is often generated by low-cost rectifier bridges. I received some HEXFRED diodes (fast / slow recovery) from onnosr, these completely eliminated the last bits of noise / hum introduced by the power amplifiers. I already used schottky diodes in the DI DAC (11DQ10). Both Schottky and fast-slow recovery diodes prevent switching noise and peak currents introduced by the diode itself during polarity change.
The DI 16 can be built for a reasonable price, that's also one of the reasons I designed it. It has the typical DI DAC properties, lot's of detail, analog natural sound and high phase accuracy. The only bottle-neck is the higher distortion of the TDA1543 chips, still it managed to outperform my twin TDA1541A DAC with 8th order Butterworth filter.
The Modified DI 8M is the top performer, building it is more expensive, but performance is on a whole different level, direct comparisons with high-performance 24 bit /192 KHz upsampling CD transports, and SACD players showed that the DI 8M revealed much more detail and sounded much clearer. The DI 8M has a very neutral and transparent sound, and fast impulse response.
The added tube diff amp reduces the effects of thermal memory, and the possible problems with the high feedback factor in the unity-gain LM4562 diff amp. Only the diff amp is a hybrid amp (OP-amp + tube OP-amp in parallel). The LM4562 diff amp delivers approx. 2/3 of the output signal now, both noise and distortion (THD) is much lower than a tube-only diff amp / output stage. Since the DI DACs have very high internal signal amplitude, a resistive output attenuator is needed, DI 8M output impedance is 600 Ohm typical.
Seems my previous post ended up at the wrong thread, so I repost it
DI DACs need Philips format I2S 64 BCK / WS in order for the timing module to interpolate correctly, if your I2S source has a different format, conversion is needed. Easiest way is the use of a SPDIF audio receiver, followed by a shiftregister reclocker (SPDIFDI2S module).
DI DACs interpolate, so they create higher initial resolution when compared to NOS DACs. Interpolation is divided over two DAC groups, one inverted, one non-inverted group. The balanced design reduces common errors, improves CMMR, and most important, provides a DC
coupled output (no added distortion by coupling cap or transformer). Two I/V converters / channel are needed, these converters need to have excellent tracking (same gain / linearity), accuracy needs to be at least 0.1% or better. The DI 8M uses 0.01% bulk metal foil precision resistors to achieve optimal tracking. If gain / linearity differs in both I/V stages, additional bit errors are introduced.
The interpolation results in a slow rolloff filter that attenuates HF images enough to prevent problems in the rest of the audio equipment. Attenuation is sufficient to leave-out the analog filter, enabling excellent phase accuracy.
I can't guarantee optimal DI DAC performance when different I/V circuits are used. The current LM4562 class A I/V converters with bulk metal foil feedback resistors are extremely accurate, high linearity, very low THD, low DC offset voltage, and fast response. This is very difficult to achieve with any kind of discrete circuit, especially when two virtually identical I/V stages are needed.
If a balanced output is required, the diff amp can be left out, and both I/V converter outputs can be connected to a XLR output. The following amplifier with balanced input will then replace the diff amp stage in the DI DAC. However, when that amplifier isn't accurate enough (amplitude / linearity difference between inverted and non-inverted input), bit errors are introduced, degrading sound quality.
I use higher amplitude output signals (2V RMS), and short semi-balanced Litz wire interlinks. My MPA80 power amps have a gain of only 20x. This combination also produces higher resolution at low volume settings. Noise / hum levels are extremely low / inaudible, even when listening a few inches away from the speaker chassis with no signal applied. XLR interlinks are useful when using longer interlinks, but these longer interlinks could also degrade sound quality (capacitance). Another advantage of the RCA outputs is that the diff amp is located very close to the I/V converters.
Noise / hum is often generated by low-cost rectifier bridges. I received some HEXFRED diodes (fast / slow recovery) from onnosr, these completely eliminated the last bits of noise / hum introduced by the power amplifiers. I already used schottky diodes in the DI DAC (11DQ10). Both Schottky and fast-slow recovery diodes prevent switching noise and peak currents introduced by the diode itself during polarity change.
The DI 16 can be built for a reasonable price, that's also one of the reasons I designed it. It has the typical DI DAC properties, lot's of detail, analog natural sound and high phase accuracy. The only bottle-neck is the higher distortion of the TDA1543 chips, still it managed to outperform my twin TDA1541A DAC with 8th order Butterworth filter.
The Modified DI 8M is the top performer, building it is more expensive, but performance is on a whole different level, direct comparisons with high-performance 24 bit /192 KHz upsampling CD transports, and SACD players showed that the DI 8M revealed much more detail and sounded much clearer. The DI 8M has a very neutral and transparent sound, and fast impulse response.
The added tube diff amp reduces the effects of thermal memory, and the possible problems with the high feedback factor in the unity-gain LM4562 diff amp. Only the diff amp is a hybrid amp (OP-amp + tube OP-amp in parallel). The LM4562 diff amp delivers approx. 2/3 of the output signal now, both noise and distortion (THD) is much lower than a tube-only diff amp / output stage. Since the DI DACs have very high internal signal amplitude, a resistive output attenuator is needed, DI 8M output impedance is 600 Ohm typical.
Hi maxlorenz,
The ultra low jitter clock should improve sound quality significantly.
Well I put a copper foil screen on the MPA80 Audyn input coupling capacitor and grounded the foil close to the input, hum is inaudible now.
I could make some using the CNC milling machine, got some more requests about these heatsinks.
What drivers? if XP works, Ubuntu should work for sure on the same hardware. There is also a new version, GutsyGibbon (Ubuntu 7.10), perhaps you could try it.
The ultra low jitter clock should improve sound quality significantly.
Well I put a copper foil screen on the MPA80 Audyn input coupling capacitor and grounded the foil close to the input, hum is inaudible now.
I could make some using the CNC milling machine, got some more requests about these heatsinks.
What drivers? if XP works, Ubuntu should work for sure on the same hardware. There is also a new version, GutsyGibbon (Ubuntu 7.10), perhaps you could try it.
Hi -ecdesigns-,
No time to swap clocks yet...I have been busy tweaking my active crossover's power supply because, as you said, when one achieves better resolution it becomes evident that the other parts of the system are limiting the performance.
That said, and at the risk of being called stuborn, I think we can achieve even better sound by tweaking the DAC and output section's power supplies
My first attempt with a gyrator was awful because it probably was too slow, as you said. I have played with a home made gyrator based on BC547->D44H11->LM317/LT1086 with excellent results on other DAC's.
There's even another recommended "regulator", with the linear reg preceding the gyrator:
http://www.pinkfishmedia.net/forum/showthread.php?t=39990
These are the options I plan to test on an uncertain future...
How strange, it is not supposed to bring improvements in axial film caps, based on postulated hypothesis...better keep esotheric audio discussion off line...we can wake up the audio Sanedrin
Oops! too late. I already bought some. But I will need some for my other DI16 future upgrade to DI8*4
Sorry, I meant drivers for some players (software), like Dr.dk netradio's player and Naxos.com player, to which I already suscribed for one year
Bye,
M
No time to swap clocks yet...I have been busy tweaking my active crossover's power supply because, as you said, when one achieves better resolution it becomes evident that the other parts of the system are limiting the performance.
That said, and at the risk of being called stuborn, I think we can achieve even better sound by tweaking the DAC and output section's power supplies
My first attempt with a gyrator was awful because it probably was too slow, as you said. I have played with a home made gyrator based on BC547->D44H11->LM317/LT1086 with excellent results on other DAC's.
There's even another recommended "regulator", with the linear reg preceding the gyrator:
http://www.pinkfishmedia.net/forum/showthread.php?t=39990
These are the options I plan to test on an uncertain future...
How strange, it is not supposed to bring improvements in axial film caps, based on postulated hypothesis...better keep esotheric audio discussion off line...we can wake up the audio Sanedrin
Oops! too late. I already bought some. But I will need some for my other DI16 future upgrade to DI8*4
Sorry, I meant drivers for some players (software), like Dr.dk netradio's player and Naxos.com player, to which I already suscribed for one year
Bye,
M