Thanks Julien, my DAC is playing music now. One thing I notice is that SAA7220 is running hot in comparing to anything else. This is running DAC in open air. It is very close to my hot water which is 50C/120F. Is this normal? Oh yes! It doesn't take long to get to that temperature, within 20 min.
The LM317 on U5 is running warmer that any of the rest but is no way near the SAA7220.
Sam
The LM317 on U5 is running warmer that any of the rest but is no way near the SAA7220.
Sam
hi samL,
7220P/B was a digital filter. it will hot. don't worry for it. I hadn't increase any operate voltage for it. don't worry. 1541a & 7220P/B was 1980~1990 products. working temp will higher then nowadays chips. but all will safe working. I had switch my DAC over two months. My design was suppose U 24 hours operate to less any run in time.
happy listening!
thx
thomas
7220P/B was a digital filter. it will hot. don't worry for it. I hadn't increase any operate voltage for it. don't worry. 1541a & 7220P/B was 1980~1990 products. working temp will higher then nowadays chips. but all will safe working. I had switch my DAC over two months. My design was suppose U 24 hours operate to less any run in time.
happy listening!
thx
thomas
Hi Thomas,
Thanks. I am running in the DAC at the moment although I have not build the case for it yet. Music is more important
Everything is on a piece of MDF at the moment 
After 4 hours of running in, must say I am quite please with it. I have a mod Pioneer 667 DVD player with Opa627 opamp and blackgate caps. Never think highly about the player until I got the Baresford TC7510 MKV about 4 months ago. Well, my mod player give the TC7510 a good run for its money. For less than $100 I spend on the mod, it is extremely value for money. As for your DAC, it got the high but without the harsh. Has midrange clarity with a more quiet background and music flow with less effort. On a slow pace female vocal, I can live with my player with no problem however when the music get into its climax, my mod pioneer will start to loose its grips and music will become incoherence. Everything will sound very flat with high noise level. This may due to me using a 10K DACT attenuator as preamp. Your DAC however is holding its candle on this and continue to 'dance' when the music get tough. Which is a quality I am looking for. This may due to the hefty power supply or maybe the reclocking, or maybe both.
The bass is on par with my player but I think it will get better after a longer burn in. What I am quite keen to do other than building a case is try pairing OP42 with Opa627. Have a few mod in mind but will wait till it been nicely burn it.
Btw, did I mention that I am using a 2M CAT6 network cable as the digital interconnect for your DAC? Well, a last minute mock up as your DAC is sitting on the floor and too far from the amp. Consider how I set it up and the sound I am getting ... I am a happy man.
Thanks. I am running in the DAC at the moment although I have not build the case for it yet. Music is more important
Everything is on a piece of MDF at the moment After 4 hours of running in, must say I am quite please with it. I have a mod Pioneer 667 DVD player with Opa627 opamp and blackgate caps. Never think highly about the player until I got the Baresford TC7510 MKV about 4 months ago. Well, my mod player give the TC7510 a good run for its money. For less than $100 I spend on the mod, it is extremely value for money. As for your DAC, it got the high but without the harsh. Has midrange clarity with a more quiet background and music flow with less effort. On a slow pace female vocal, I can live with my player with no problem however when the music get into its climax, my mod pioneer will start to loose its grips and music will become incoherence. Everything will sound very flat with high noise level. This may due to me using a 10K DACT attenuator as preamp. Your DAC however is holding its candle on this and continue to 'dance' when the music get tough. Which is a quality I am looking for. This may due to the hefty power supply or maybe the reclocking, or maybe both.
The bass is on par with my player but I think it will get better after a longer burn in. What I am quite keen to do other than building a case is try pairing OP42 with Opa627. Have a few mod in mind but will wait till it been nicely burn it.
Btw, did I mention that I am using a 2M CAT6 network cable as the digital interconnect for your DAC? Well, a last minute mock up as your DAC is sitting on the floor and too far from the amp. Consider how I set it up and the sound I am getting ... I am a happy man.
hi samL,
take a look of this.
i was prepare the tube buffer PCb & this.
nano amorphous IV transformers.
turn ratio was 1:10.
running 10ma current.
take a look. U can use this to relief the op-amp IV region.
thx
thomas
take a look of this.
i was prepare the tube buffer PCb & this.
nano amorphous IV transformers.
turn ratio was 1:10.
running 10ma current.
take a look. U can use this to relief the op-amp IV region.
thx
thomas
An externally hosted image should be here but it was not working when we last tested it.
Hi Thomas,
What is your DAC output impedance when using opamp buffers? What about when using the tube buffers?
Will be keen to try the tube buffers if it is below 50 ohm. I am quite keen to build the Lightspeed Attenuator by George. He explain the requirement of the source at the end of page 1.
http://www.diyaudio.com/forums/showthread.php?postid=926676#post926676
Also, can I replace the C3, C5 on the I/V&LPF (single opamp) to a 6.3V cap? To what I can see they are directly on signal path and I would like to use the blackgate NX. Also, the 100uF value, does it control the signal roll-off? What frequency is that?
What is your DAC output impedance when using opamp buffers? What about when using the tube buffers?
Will be keen to try the tube buffers if it is below 50 ohm. I am quite keen to build the Lightspeed Attenuator by George. He explain the requirement of the source at the end of page 1.
http://www.diyaudio.com/forums/showthread.php?postid=926676#post926676
Also, can I replace the C3, C5 on the I/V&LPF (single opamp) to a 6.3V cap? To what I can see they are directly on signal path and I would like to use the blackgate NX. Also, the 100uF value, does it control the signal roll-off? What frequency is that?
A simple upgrade using left over plated Teflon Cat5 cable as connection cable. Improvement is like replacing factory RCA cable with a teflon Cat5 cable.. well not as big improvement but the quality is there. For $2.00, it is worth the effort and can easily switch back. For those who have some good offcuts wire/cable, this is a good place to use them.
Will solder them directly when I have a permanent home for the DAC
Have fun
Will solder them directly when I have a permanent home for the DAC
Have fun
Attachments
Sam,
Looks like you`re having fun with this DAC.
I`m using the I/V board with 4 op-amps (iv1) as it has a higher output than the simpler version (I need to drive a passive TVC pre and a sub). This board also outputs the right (+) polarity, the simpler one doesn`t invert polarity, so you have to do it somewhere else in the system, like the speakers if you want an in-phase system output.
One thing I`ll be trying soon is to use the spare +5V outputs in the PS to supply the clock and SAA7220 chip independently. That might improve things when using the re-clock and OS circuits.
I`m also considering using a low noise Jfet I/V instead of the op-amp I/V.
Regarding the DC blocking cap(s) at the output, you can use a low voltage cap if you like. I only measured about 2VDC at the output. But you`ll probably be better off with a polypropylene film cap (or Teflon). Something between 4.7uF and 10uF. On the dual op-amp board I replaced C7 and C8 with Auricaps and bypassed C11 and C12 since there was no DC present at the output.
I believe the output impedance on both op-amp I/V boards is 100K.
PS: nice cable upgrade. I shall get to that once I have a final layout for the DAC.
Looks like you`re having fun with this DAC.
I`m using the I/V board with 4 op-amps (iv1) as it has a higher output than the simpler version (I need to drive a passive TVC pre and a sub). This board also outputs the right (+) polarity, the simpler one doesn`t invert polarity, so you have to do it somewhere else in the system, like the speakers if you want an in-phase system output.
One thing I`ll be trying soon is to use the spare +5V outputs in the PS to supply the clock and SAA7220 chip independently. That might improve things when using the re-clock and OS circuits.
I`m also considering using a low noise Jfet I/V instead of the op-amp I/V.
Regarding the DC blocking cap(s) at the output, you can use a low voltage cap if you like. I only measured about 2VDC at the output. But you`ll probably be better off with a polypropylene film cap (or Teflon). Something between 4.7uF and 10uF. On the dual op-amp board I replaced C7 and C8 with Auricaps and bypassed C11 and C12 since there was no DC present at the output.
I believe the output impedance on both op-amp I/V boards is 100K.
PS: nice cable upgrade. I shall get to that once I have a final layout for the DAC.
Hi Julian,
Thanks for sharing your mod. I have not started anything on the I/V opamp board as I am not sure if I will stay with single or double opamp. Well, you info on the polarity issue on the single opamp will help with my decision. A low noise Jfet I/V will be better but only if it is not too big and easy to build.
One thing I have done is replaced the C33, C35 and C37 on the TDA1541A board with 470uF 35V ZL that I have. This change some character of the sound. Music have a bit more bounce and with a bit better flow but lost a bit of 'thumb' on the bass area. However, this is base on listening to one CD. Will leave it there a bit longer to see if it is a keeper.
As for the recolocking part, well I was thinking of replacing the stock 11.2896MHz crystal with a lower noise version like this http://shop.hifidiy.net/product/152.htm
Another alternative is Tent's crystal but don't think it is a drop in replacement.
Looks like we all have ideas of improving this DAC. Will like to hear what others do with their.
Thanks for sharing your mod. I have not started anything on the I/V opamp board as I am not sure if I will stay with single or double opamp. Well, you info on the polarity issue on the single opamp will help with my decision. A low noise Jfet I/V will be better but only if it is not too big and easy to build.
One thing I have done is replaced the C33, C35 and C37 on the TDA1541A board with 470uF 35V ZL that I have. This change some character of the sound. Music have a bit more bounce and with a bit better flow but lost a bit of 'thumb' on the bass area. However, this is base on listening to one CD. Will leave it there a bit longer to see if it is a keeper.
As for the recolocking part, well I was thinking of replacing the stock 11.2896MHz crystal with a lower noise version like this http://shop.hifidiy.net/product/152.htm
Another alternative is Tent's crystal but don't think it is a drop in replacement.
Looks like we all have ideas of improving this DAC. Will like to hear what others do with their.
xaudiox said:
Right now I`m runing it only in NOS, no re-clock. I found OS to be a little less detailed than NOS (both settings without re-clock). I`ll soon try using an idependent +5VDC supply to the clock and OS chip and compare again. I think that should help the sound when using these circuits.
Julien_M said:
That is what I found too. The 'wind' sound in the beginning of "Hotel California" is a big clearer with NOS. However I find the OS have better authority. Both with reclocking. There time I prefer the NOS and there time I prefer OS.
Have not tried the other settings. Man, there so many setting available on this DAC to tailor to taste, it is incredible. 
Julien, do keep us inform about your test on independent +5VDC to the clock and OS chips.
Have fun everyone
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