Finished the DAC
I have just finished the DAC with the opamp buffer AD797 and initial impressions are good, excellent soundstage although the highs are a little soft.
How much difference does the tube preamp make? Where can I source the tubes at a reasonable price?
Have people been tweaking the DAC? Care to post what tweaks have worked for you?
Has anyone tried the CS8414 filter adjustment that seems popular (the "wildmokeysects" filter) 270R, 0.22 uF, and 2200/3300 pF?
One last question, Thomas indicates from a previous post that the following should be adjusted:
R22/44 jumpered. R22 is part of another voltage regulator and shorting this will also short a cap. I can't find R44.
R8/R42 change to 820 ohms. R42 is a 68 ohm 2w resistor providing current to a regulator, surely you dont want to increase this to 820 ohms? Also, R8 is the top of a voltage divider for another regulator and quite different from R42. Is this correct?
R28/R47/R39/R48 remove. These are the i/v resistors. If using the op amp buffer you need these to convert the output current to a voltage to amplify, surely you dont want to remove these unless the opamp is setup to do the i/v conversion?
Regards,
Dean
I have just finished the DAC with the opamp buffer AD797 and initial impressions are good, excellent soundstage although the highs are a little soft.
How much difference does the tube preamp make? Where can I source the tubes at a reasonable price?
Have people been tweaking the DAC? Care to post what tweaks have worked for you?
Has anyone tried the CS8414 filter adjustment that seems popular (the "wildmokeysects" filter) 270R, 0.22 uF, and 2200/3300 pF?
One last question, Thomas indicates from a previous post that the following should be adjusted:
R22/44 jumpered. R22 is part of another voltage regulator and shorting this will also short a cap. I can't find R44.
R8/R42 change to 820 ohms. R42 is a 68 ohm 2w resistor providing current to a regulator, surely you dont want to increase this to 820 ohms? Also, R8 is the top of a voltage divider for another regulator and quite different from R42. Is this correct?
R28/R47/R39/R48 remove. These are the i/v resistors. If using the op amp buffer you need these to convert the output current to a voltage to amplify, surely you dont want to remove these unless the opamp is setup to do the i/v conversion?
Regards,
Dean
More impressions
After letting the DAC burn in all day, I listened to it for a couple of hours tonight. As reported above, the DAC is smooth with excellent soundstange / imaging, however the highs are a little soft and undefined, to be expected with a NOS DAC (poor resolution above 10K and sinc attentuation).
As I am using a PC with a pro audio card (EMU 1820M) as the source, I thought I'd try a very high quality resampling to 88.1Khz. What a difference this makes, the highs spring to life (as the sinc envelope is pushed out above 20KHz), the music seems more dynamic and even the bass is firmer. Occassionally the DAC will not start a song correctly and you get a buzz out of the speakers, I assume due to the high sampling rate. Worth trying for those who can do this (and yes, I know it is no longer a true NOS DAC when you do this).
I'm still interested if anyone has any answers to my questions above and can share their experience tweaking this amp. An obvious tweak would be to remove the output cap in the opamp buffer if the offset is not too great (OK for FET input opamps).
Regards,
Dean
After letting the DAC burn in all day, I listened to it for a couple of hours tonight. As reported above, the DAC is smooth with excellent soundstange / imaging, however the highs are a little soft and undefined, to be expected with a NOS DAC (poor resolution above 10K and sinc attentuation).
As I am using a PC with a pro audio card (EMU 1820M) as the source, I thought I'd try a very high quality resampling to 88.1Khz. What a difference this makes, the highs spring to life (as the sinc envelope is pushed out above 20KHz), the music seems more dynamic and even the bass is firmer. Occassionally the DAC will not start a song correctly and you get a buzz out of the speakers, I assume due to the high sampling rate. Worth trying for those who can do this (and yes, I know it is no longer a true NOS DAC when you do this).
I'm still interested if anyone has any answers to my questions above and can share their experience tweaking this amp. An obvious tweak would be to remove the output cap in the opamp buffer if the offset is not too great (OK for FET input opamps).
Regards,
Dean
Deandob,
I suggest that you try the tube buffer and also make use of the reclock module. The opamp output stage was not good enough for me. The reclock module is definitely an improvement.
These preamp tubes are not expensive and are readily available online. I bought mine on eBay.
Many parts can also be changed for better parts.
I suggest that you try the tube buffer and also make use of the reclock module. The opamp output stage was not good enough for me. The reclock module is definitely an improvement.
These preamp tubes are not expensive and are readily available online. I bought mine on eBay.
Many parts can also be changed for better parts.
Help needed with tube buffer
Hi,
I am trying to get the tube-buffer working for some weeks now.
But for some reason I cannot get a non distorted sound out of it.
If I put in the 6922 tubes, which according to the internet is fully compatible with the 6dj8, the signal is completely distorted and weakened.
If I put in the 6C45PI the signal is amplified but still distorted. But a lot less then the 6922.
What happens is when I feed the DAC with a 1kHz 0dB sinus signal the "tops" are a bit "flattened". With the 6922 the signal does not even look like a sinus anymore.
When listening to music the 6C45 it sounds "good" but you can hear distortion through it. When listening to the 6922 the sound level is low and completely distorted.
I did some measurements on the DC levels:
the 6.3 V DC is present and on the correct pins.
Between pin 2 of J12 and R16 (R22, R49, R50) I have about 180 VDC.
Between pin 2 of J9 and R16 I have about 30 VDC.
I have not put the 82 Ohms resitor between the DAC board and the tube-buffer (I thought this is only needed for the Opamp buffer).
I have not changed anything on the buffer and build it according to the diagram.
Any help would be very much appreciated because I have absolutely no experience with tubes.
Thanks in advance,
Jeroen
Hi,
I am trying to get the tube-buffer working for some weeks now.
But for some reason I cannot get a non distorted sound out of it.
If I put in the 6922 tubes, which according to the internet is fully compatible with the 6dj8, the signal is completely distorted and weakened.
If I put in the 6C45PI the signal is amplified but still distorted. But a lot less then the 6922.
What happens is when I feed the DAC with a 1kHz 0dB sinus signal the "tops" are a bit "flattened". With the 6922 the signal does not even look like a sinus anymore.
When listening to music the 6C45 it sounds "good" but you can hear distortion through it. When listening to the 6922 the sound level is low and completely distorted.
I did some measurements on the DC levels:
the 6.3 V DC is present and on the correct pins.
Between pin 2 of J12 and R16 (R22, R49, R50) I have about 180 VDC.
Between pin 2 of J9 and R16 I have about 30 VDC.
I have not put the 82 Ohms resitor between the DAC board and the tube-buffer (I thought this is only needed for the Opamp buffer).
I have not changed anything on the buffer and build it according to the diagram.
Any help would be very much appreciated because I have absolutely no experience with tubes.
Thanks in advance,
Jeroen
Member
Joined 2002
Tube buffer
Jleaman,
Did you get your buffer working correctly?
If yes could you tell me which voltage levels you are having on the tube buffer.
I am not sure if this is the problem, but according to the diagram they should be arround 200V at R16 but mine is a lot lower.
Jleaman,
Did you get your buffer working correctly?
If yes could you tell me which voltage levels you are having on the tube buffer.
I am not sure if this is the problem, but according to the diagram they should be arround 200V at R16 but mine is a lot lower.
Member
Joined 2002
Mine is working but not the way i wanted it to. Mine is not distorting it is changing the frequency range 🙁
jleaman said:
IV resistors on the DAC R28/R39 can be changed to 47 to 68 ohm to increase output for tube stage.
Try removing the two inductors L3/L4 on the input of the tube buffer and repalcing them with 7.5K 1/2 resistors. Also check the value of these caps 1n 63V C23 C24 C42 C48 they form a CLC input filter with the inductors. It may be best to run a CRC on the input filter.
Anthony
Member
Joined 2002
Member
Joined 2002
Member
Joined 2002
hi all,
i was back. Alert, alert, alert!!!!!
Don't paid much money to buy the S1 or S2 chips.
I call one of my friend in china & take me to go to the reprint base of many IC chips. Most was famous as PCM1704 to K grade, AD1862 to N-J grade, opa 627Ap to BP etc.
some was use NE5532 or other chip IC reprint to famous one.
such as in TDA1541a to S1 or S2.
i told them that I was the middle man & hope to see the re-print chips. I will order many chips MOV 200pcs. I ask that can i paid money & take them away. they said no. I said if not how can I show to my boss to see the quality.
At last they only agree to show me the mould for print. Sp pls take care, In my opinions, Pls don't buy S1 or S2 in China or east asia. so why recently quite many 1541a S1 or S2 chips in market.
take care feiends. They use polishing machine to erase theold words & re-print the new one. its not east to versify the reprint or not.
I hadn't ask them any overseas order or not. So I did not know any chips was sold to oversea or not.
BTW, take care!!!!!!!!!!!!!!!
thx
thomas
i was back. Alert, alert, alert!!!!!
Don't paid much money to buy the S1 or S2 chips.
I call one of my friend in china & take me to go to the reprint base of many IC chips. Most was famous as PCM1704 to K grade, AD1862 to N-J grade, opa 627Ap to BP etc.
some was use NE5532 or other chip IC reprint to famous one.
such as in TDA1541a to S1 or S2.
i told them that I was the middle man & hope to see the re-print chips. I will order many chips MOV 200pcs. I ask that can i paid money & take them away. they said no. I said if not how can I show to my boss to see the quality.
At last they only agree to show me the mould for print. Sp pls take care, In my opinions, Pls don't buy S1 or S2 in China or east asia. so why recently quite many 1541a S1 or S2 chips in market.
take care feiends. They use polishing machine to erase theold words & re-print the new one. its not east to versify the reprint or not.
I hadn't ask them any overseas order or not. So I did not know any chips was sold to oversea or not.
BTW, take care!!!!!!!!!!!!!!!
thx
thomas
Attachments
Pinging Sceglar
Hi,
Trying to speak to Shane (Sceglar) about your USB implementation...
Could you email me privately?? I could not reach you trough this website. My email is ligascon@hotmail.com
Thanks.
Luis
Hi,
Trying to speak to Shane (Sceglar) about your USB implementation...
Could you email me privately?? I could not reach you trough this website. My email is ligascon@hotmail.com
Thanks.
Luis
hi good news,
this is my recent order!
Quotation
Qty Prefix Part Number Cust. PN Mfr. DC Cond. Delivery Price
------- ------- ---------------- ---------------- ----- ---- ------ --------- --------
200 SAA 7220PB PHILI 95+ New $5.7000
Comments:
Thank you for this opportunity to be of service to you.
Best regards,
www.zdi.com
chips will arrive new week.
I will free to all old clients.
only need to pay. USD 4.5 for postage.
chips will free to old clients to upgrade.
will collect with IC socket.
thx
thomas
this is my recent order!
Quotation
Qty Prefix Part Number Cust. PN Mfr. DC Cond. Delivery Price
------- ------- ---------------- ---------------- ----- ---- ------ --------- --------
200 SAA 7220PB PHILI 95+ New $5.7000
Comments:
Thank you for this opportunity to be of service to you.
Best regards,
www.zdi.com
chips will arrive new week.
I will free to all old clients.
only need to pay. USD 4.5 for postage.
chips will free to old clients to upgrade.
will collect with IC socket.
thx
thomas
riotubes said:
It's a 4x oversampling digital filter. With it installed the dac won't be non oversampling anymore though.
Thomas, with your dac is there a switch installed to enable/disable this filter?
Hi,
as I previous said.
all the pervious ( old clients) will enjoy automatic upgrade service. They only need to pay the postage.
So why I order 200 pcs SAA7220P/B grade.
I will post one chips for them to upgrade by themselvers.
certainly a little re-work was needed.
In vintage design from philips. Such as CD95 DA95 or other DAC which use TDA1541a chips as the modern marantz project D-1.
All will use this SAA7220 chips with the 1541a, running in 4X already. If running in 8x the sound will dry & thin, lost most smooth. There will be the only one Digital filter can support for 1541a. Its SAA7220. Since 1541a was operate in I2S format only. Other digital filter such as the DF1700, 1704,NPC SM5842,5843 cannot support or said it must combine with some circuit converted back into I2S format to work.
If U felt NOS was a little bit lack of HF, try mix with SAA7220 & running in 4X mode. U will got back more HF but the smooth & high density MF will not distort more.
This SAA7220 can use jumper enable/disable.
Non-oversampling was a very good idea from audionote, which had lower digital noise, more smooth , high density LP sound, more analog soundstage but the Hf will roll of serious or said little bit weak in HF. Normally diyers will combine with reclock such as the Oscillator (XO r TCXO) with the 74XXXX ICs to make it operate most linear & got back some HF. but the best format still need combine with Oscillator & saa7220.
Actually the best was used this format.
Combine this format there will had one machine in market.
Its
Marantz project D-1.
Project D1 (\500,000) D/A.
http://www.geocities.co.jp/Hollywood-Miyuki/7088/projectd1.htm
I bought one second hand from Japan for me to compare with the new coming machine.
The new version coming will operate in this format.
Standard version ( Fully assemble).
Input source: RCA, BNC, OPtical, TTL,XLR.
Chips. Nano pulse input trans,CS8414, SAA7220, TCXO,74HCXXXX & TDA1541a.
Digital data steam input>> Nano-amorphous pulse transformers.
then pass CS8414>>SAA7220( Philips special design for 1541a Digital filter) ( can default & operate in NOS stage)(With TCXO 2ppm with 74HCXXXX as the reclock) then pass into tda1541a.
Decoupling caps was 0.1~022uf tantalum capacitor which advise from member of this forum & also will follow with standard 0.22uf philips MKT caps for exchange.
Use Dual op-amp which will follow with 4 pcs OPA627 by the adapter.
All fit into one aluminium chassis.
fully assemble. After china funish it I will pre-run in 24 hrs & re-test.
I guess we all were computor use. Most diyers there will had OLD CD-Rom on hand. So every standard set will follow with one Cd-com controllor with remote control. So why the new DAC had TTL input was fit for the CD-Rom input. BTW, If U had plextor DVD rom U will be the lucky one. Because Plextor had silient mode to ad the start speed of the rom. This will not easy to damage the CD-disk. But another cd-romalso compatible but I strong suggest use one old disk to test first.
http://www.plextor.com/
At last will be the price.
large decrease already, due to I openone production line in China already. low Labour cost offer me to provide good price products to diyers.
Full set ( fully assemble DAC with the CD-rom controllor w/ very slim thin size remote control will USD 220~250 only.
Price was included the EMS postage already.
Every DAC will weight over 5kg. Postage will cost me USD 65.
So U only cost around USD 180 for a fully assemble Dac. It is a very good rice.
full sample will post to forum after 10 days.
I prepare this machine which was test with marantz D-1 already.
Pls saw the project that I bought from japan to test with the new dac.
It will be a good Dac, low noise than previous one & zandan labs.
very good P/C ratio & 100% fully assemble.
It can be upgrade by another coming USB 2.0 receiver which was advise another diyer in this forum. Chips was PCM 2708.
But it can exchange chips by yourself, Support 2706~2708 & CM 106.
support Win98 SE / Win ME / Win 2000 / Win XP and Mac OS9 / OS X.
U can use your standard or AV computor cd-rom machine rundisk or save all the music ( non-compress version ) in hard disk & work with this DAC.
This Options USB 2.0 spdif card was factory funish by all SMD parts but the resistors I choose was 0805 such as the 1/6watts standard resistors. I prepare space for diyers to change parts already.
thx
thomas
as I previous said.
all the pervious ( old clients) will enjoy automatic upgrade service. They only need to pay the postage.
So why I order 200 pcs SAA7220P/B grade.
I will post one chips for them to upgrade by themselvers.
certainly a little re-work was needed.
In vintage design from philips. Such as CD95 DA95 or other DAC which use TDA1541a chips as the modern marantz project D-1.
All will use this SAA7220 chips with the 1541a, running in 4X already. If running in 8x the sound will dry & thin, lost most smooth. There will be the only one Digital filter can support for 1541a. Its SAA7220. Since 1541a was operate in I2S format only. Other digital filter such as the DF1700, 1704,NPC SM5842,5843 cannot support or said it must combine with some circuit converted back into I2S format to work.
If U felt NOS was a little bit lack of HF, try mix with SAA7220 & running in 4X mode. U will got back more HF but the smooth & high density MF will not distort more.
This SAA7220 can use jumper enable/disable.
Non-oversampling was a very good idea from audionote, which had lower digital noise, more smooth , high density LP sound, more analog soundstage but the Hf will roll of serious or said little bit weak in HF. Normally diyers will combine with reclock such as the Oscillator (XO r TCXO) with the 74XXXX ICs to make it operate most linear & got back some HF. but the best format still need combine with Oscillator & saa7220.
Actually the best was used this format.
Combine this format there will had one machine in market.
Its
Marantz project D-1.
Project D1 (\500,000) D/A.
http://www.geocities.co.jp/Hollywood-Miyuki/7088/projectd1.htm
I bought one second hand from Japan for me to compare with the new coming machine.
The new version coming will operate in this format.
Standard version ( Fully assemble).
Input source: RCA, BNC, OPtical, TTL,XLR.
Chips. Nano pulse input trans,CS8414, SAA7220, TCXO,74HCXXXX & TDA1541a.
Digital data steam input>> Nano-amorphous pulse transformers.
then pass CS8414>>SAA7220( Philips special design for 1541a Digital filter) ( can default & operate in NOS stage)(With TCXO 2ppm with 74HCXXXX as the reclock) then pass into tda1541a.
Decoupling caps was 0.1~022uf tantalum capacitor which advise from member of this forum & also will follow with standard 0.22uf philips MKT caps for exchange.
Use Dual op-amp which will follow with 4 pcs OPA627 by the adapter.
All fit into one aluminium chassis.
fully assemble. After china funish it I will pre-run in 24 hrs & re-test.
I guess we all were computor use. Most diyers there will had OLD CD-Rom on hand. So every standard set will follow with one Cd-com controllor with remote control. So why the new DAC had TTL input was fit for the CD-Rom input. BTW, If U had plextor DVD rom U will be the lucky one. Because Plextor had silient mode to ad the start speed of the rom. This will not easy to damage the CD-disk. But another cd-romalso compatible but I strong suggest use one old disk to test first.
http://www.plextor.com/
At last will be the price.
large decrease already, due to I openone production line in China already. low Labour cost offer me to provide good price products to diyers.
Full set ( fully assemble DAC with the CD-rom controllor w/ very slim thin size remote control will USD 220~250 only.
Price was included the EMS postage already.
Every DAC will weight over 5kg. Postage will cost me USD 65.
So U only cost around USD 180 for a fully assemble Dac. It is a very good rice.
full sample will post to forum after 10 days.
I prepare this machine which was test with marantz D-1 already.
Pls saw the project that I bought from japan to test with the new dac.
It will be a good Dac, low noise than previous one & zandan labs.
very good P/C ratio & 100% fully assemble.
It can be upgrade by another coming USB 2.0 receiver which was advise another diyer in this forum. Chips was PCM 2708.
But it can exchange chips by yourself, Support 2706~2708 & CM 106.
support Win98 SE / Win ME / Win 2000 / Win XP and Mac OS9 / OS X.
U can use your standard or AV computor cd-rom machine rundisk or save all the music ( non-compress version ) in hard disk & work with this DAC.
This Options USB 2.0 spdif card was factory funish by all SMD parts but the resistors I choose was 0805 such as the 1/6watts standard resistors. I prepare space for diyers to change parts already.
thx
thomas
Attachments
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