Hello Thomas,
I was looking at the DAC schematics and I found a SK6 jumper. Is there any advantage or disadvantage of having both DACs synchronized?
Thanks.
I was looking at the DAC schematics and I found a SK6 jumper. Is there any advantage or disadvantage of having both DACs synchronized?
Thanks.
Phillips CDM9 Pro opening/closing gear
Hi,
any diyers lke to order cdm9, CDM1,M4 mechanism & cdm9, M4 wheel .
pls email to me. USD 23 per pair CMD9 or USD 28 CDM4 wheel. Brand new with excellent plastic material.More durable0. Price include posatge & paypal charge.
pls email to thomas@diyaudiocraft.com
thx
thomas
Hi,
any diyers lke to order cdm9, CDM1,M4 mechanism & cdm9, M4 wheel .
pls email to me. USD 23 per pair CMD9 or USD 28 CDM4 wheel. Brand new with excellent plastic material.More durable0. Price include posatge & paypal charge.
pls email to thomas@diyaudiocraft.com
thx
thomas
Kit order
Hi Thomas,
I sent you email to the mail account on your web site requesting information to order your DAC kit (with 240v transformers).
Regards,
Dean
Hi Thomas,
I sent you email to the mail account on your web site requesting information to order your DAC kit (with 240v transformers).
Regards,
Dean
I tried this some time ago and the first impression was that the image was better. However later I found that the sound become a little hard. In the end I prefer to leave this jumper open.
Julien_M said:
quantran said:
That's interesting. I also tried connecting SK6 and I got a lot of noise. And the sound wasn't that great either.
Thomas, any suggestions?
Is this J6 SYN, that links the two #16 pins of the D/A chips together?
Also, are people pulling out R16 and R19 from the input section before sending I2S direct in to the D/A chips?.
thanks,
shane
Also, are people pulling out R16 and R19 from the input section before sending I2S direct in to the D/A chips?.
thanks,
shane
Hum in the Tube Buffer
Hi All,
I inspired by this thread and end up ordering this dac kit. The dac board and opamp board are perfect and working flawlessly. When I'm finish the tube board and connect it to dac board, I have a hefty hum from RCA output. The hum in one channel is louder while the music play but they are both hum. The RCA output has around 100 mv.
I try to check the circuit and soldering point but everything is fine. The AC heater of regulator tube is a bit high at 7.8 Vac. When I put 6X4 together with EZ80 then it drops to 6.8 Vac. I feel that the AC does not effect much about the hum. I connect E from all PT together and connect it to IEC ground. I noticed that the high voltage PT has generated a lot of hum and I guess that it may be the source of the hum because the hum at output and noise from PT has the same sound and tone. Can PT is the origin of this problem? Hence, I have only one transformer from Thomas, I cannot do a swap to check this problem. I try to swap many tubes for 6DJ8 including 6N1P, 7308, 6922 but the hum is still there.
Can anyone help me to solve this problem? Thanks.
Kittikun
Hi All,
I inspired by this thread and end up ordering this dac kit. The dac board and opamp board are perfect and working flawlessly. When I'm finish the tube board and connect it to dac board, I have a hefty hum from RCA output. The hum in one channel is louder while the music play but they are both hum. The RCA output has around 100 mv.
I try to check the circuit and soldering point but everything is fine. The AC heater of regulator tube is a bit high at 7.8 Vac. When I put 6X4 together with EZ80 then it drops to 6.8 Vac. I feel that the AC does not effect much about the hum. I connect E from all PT together and connect it to IEC ground. I noticed that the high voltage PT has generated a lot of hum and I guess that it may be the source of the hum because the hum at output and noise from PT has the same sound and tone. Can PT is the origin of this problem? Hence, I have only one transformer from Thomas, I cannot do a swap to check this problem. I try to swap many tubes for 6DJ8 including 6N1P, 7308, 6922 but the hum is still there.
Can anyone help me to solve this problem? Thanks.
Kittikun
Kittikun
Since we are living in the same city, you might want to e-mail me. I have 2 kits from Thomas and none of them have problem either tube or Opamp.
Withaya
Since we are living in the same city, you might want to e-mail me. I have 2 kits from Thomas and none of them have problem either tube or Opamp.
Withaya
Re: Hum in the Tube Buffer
Hello Kittikun.
Check to see if you connected J2 and J3 in the tube board. If you leave these open, you get hum. I did that mistake in the beginning.
I'm not sure if both tube regulators should be used in parallel, I think they're both included for comparison purposes.
For the rectifier tube filament supply, you can use two 1R or 1R25 2W (or higher) resistors (one for each lead) between the transformer and PCB. That will lower your AC voltage to 6.3V - 6.6V. The filament current is 600mA.
I replaced R4 and R29 with 20K resistors for a lower B+, around 230V now.
I have done a few tweaks lately with very good sonic results:
- I replaced the s/pdif input parts with higher quality ones. I used a 75R Holco resistor and a 1uF Black Gate N (non polar).
- I resolder all os-con caps flush to the PCB as to reduce lead. And I replaced eight 0.1uF bypass film caps in the power supply rails to all 3 chips with ceramic surface mount ones.
- I remove both DAC's and cleaned their pins and sockets.
These little changes brought major sonic benefits. The sound is more open and smoother. Easier on the ears. The midrange is very life like.
I'm still waiting for my TCXO for the DAC re-clock. Hopefully that will bring similar improvements. (Thomas, any news?)
I tried both single and twin DACs and they both offer advantages. One DAC is very detailed and transparent, but two DACs are very dynamic with a high output and a bigger image presentation. If you like big orchestra or chorals, by all means go for twins, the impact on crescendos is glorious. But if you prefer chamber music, a single DAC might suit you better.
kittikun said:Hi All,
I inspired by this thread and end up ordering this dac kit. The dac board and opamp board are perfect and working flawlessly. When I'm finish the tube board and connect it to dac board, I have a hefty hum from RCA output. The hum in one channel is louder while the music play but they are both hum. The RCA output has around 100 mv.
I try to check the circuit and soldering point but everything is fine. The AC heater of regulator tube is a bit high at 7.8 Vac. When I put 6X4 together with EZ80 then it drops to 6.8 Vac. I feel that the AC does not effect much about the hum. I connect E from all PT together and connect it to IEC ground. I noticed that the high voltage PT has generated a lot of hum and I guess that it may be the source of the hum because the hum at output and noise from PT has the same sound and tone. Can PT is the origin of this problem? Hence, I have only one transformer from Thomas, I cannot do a swap to check this problem. I try to swap many tubes for 6DJ8 including 6N1P, 7308, 6922 but the hum is still there.
Can anyone help me to solve this problem? Thanks.
Kittikun
Hello Kittikun.
Check to see if you connected J2 and J3 in the tube board. If you leave these open, you get hum. I did that mistake in the beginning.
I'm not sure if both tube regulators should be used in parallel, I think they're both included for comparison purposes.
For the rectifier tube filament supply, you can use two 1R or 1R25 2W (or higher) resistors (one for each lead) between the transformer and PCB. That will lower your AC voltage to 6.3V - 6.6V. The filament current is 600mA.
I replaced R4 and R29 with 20K resistors for a lower B+, around 230V now.
I have done a few tweaks lately with very good sonic results:
- I replaced the s/pdif input parts with higher quality ones. I used a 75R Holco resistor and a 1uF Black Gate N (non polar).
- I resolder all os-con caps flush to the PCB as to reduce lead. And I replaced eight 0.1uF bypass film caps in the power supply rails to all 3 chips with ceramic surface mount ones.
- I remove both DAC's and cleaned their pins and sockets.
These little changes brought major sonic benefits. The sound is more open and smoother. Easier on the ears. The midrange is very life like.
I'm still waiting for my TCXO for the DAC re-clock. Hopefully that will bring similar improvements. (Thomas, any news?)
I tried both single and twin DACs and they both offer advantages. One DAC is very detailed and transparent, but two DACs are very dynamic with a high output and a bigger image presentation. If you like big orchestra or chorals, by all means go for twins, the impact on crescendos is glorious. But if you prefer chamber music, a single DAC might suit you better.
Hi Julien,
Thanks a lot for your advice.
I try what's that you suggest. J2 and J3 are connected in the first place so it is not the source of hum. I put 1R on the AC heater of the regulator including with single and twin regulator and the hum is still there. I did not replace R4 and R29 bacuase the B+ is arounf 205 V which is OK when I put both 6DJ8 and 6C45 on board.
Finally, I notice that the 3 from 4 transformer have hum and the hum has the same tone from the tube output. Then I try to disconnect one 18-0-18 transformer for Opamp which has the loudest hum. Yes, when I turn the dac on again, the hum is much lower from the tube output. Therefore the source of hum is exactly came from the transformer but not one, they are 3 transformer, 2*18-0-18 and a high voltage transformer. I can't hear the hum when I use the Opamp output because the supply is regulate but the high voltage for tube buffer is not. The tube buffer is suseptible from the hum from their own transformer and other when they all connected on the same main supply and other transformer are also polluted the main line. I will try to replace all the transformers to see whether I can eliminate all the hum problem.
It will take sometime to order a new transformer from local factory here. Once I'm finish, I will update the result on this thread.
What do you think about my observation for the transformer?
Kittikun
Thanks a lot for your advice.
I try what's that you suggest. J2 and J3 are connected in the first place so it is not the source of hum. I put 1R on the AC heater of the regulator including with single and twin regulator and the hum is still there. I did not replace R4 and R29 bacuase the B+ is arounf 205 V which is OK when I put both 6DJ8 and 6C45 on board.
Finally, I notice that the 3 from 4 transformer have hum and the hum has the same tone from the tube output. Then I try to disconnect one 18-0-18 transformer for Opamp which has the loudest hum. Yes, when I turn the dac on again, the hum is much lower from the tube output. Therefore the source of hum is exactly came from the transformer but not one, they are 3 transformer, 2*18-0-18 and a high voltage transformer. I can't hear the hum when I use the Opamp output because the supply is regulate but the high voltage for tube buffer is not. The tube buffer is suseptible from the hum from their own transformer and other when they all connected on the same main supply and other transformer are also polluted the main line. I will try to replace all the transformers to see whether I can eliminate all the hum problem.
It will take sometime to order a new transformer from local factory here. Once I'm finish, I will update the result on this thread.
What do you think about my observation for the transformer?
Kittikun
I also have small mechanical hum from transformer but it's not going through the output. I don't think that's the problem. Don't waste your money to order more transformer. Another trick for now, let's try to by pass the L input at the tube buffer. You can use clip lead to try first if it cure the problem.
kittikun said:
Hi Kittikun,
I agree with WT. I don't think the transformers are the culprit.
The 1R resistors were a solution only for the high heater voltage so your tubes last longer.
I'm not sure if it's a good idea to keep both regulator tubes in the circuit.
I think the source of your hum could be a ground loop. How did you ground the DAC?
Did you connect the PCB grounds to earth? Try floating both PCB's.
I only have the digital PCB grounded. But it goes through a 10R resistor to earth.
Hope that helps.
Hi Julien & WT,
OK. I won't touch anything on the transformer. Now, I use only one regulator tube but the hum is still a good friend of mine. All ground of 3 boards is floating. I just connect all E from transformers to IEC ground. I will try to connect dac ground to chassis. Should I connect it directly to ground or through 10R for grounded?
WT, Do you mean that I should shorted the L input to ground to see whether the hum is still? Am I right?
Thanks everyone for your kind help. I will try and let you know.
Kittikun 😀
OK. I won't touch anything on the transformer. Now, I use only one regulator tube but the hum is still a good friend of mine. All ground of 3 boards is floating. I just connect all E from transformers to IEC ground. I will try to connect dac ground to chassis. Should I connect it directly to ground or through 10R for grounded?
WT, Do you mean that I should shorted the L input to ground to see whether the hum is still? Am I right?
Thanks everyone for your kind help. I will try and let you know.
Kittikun 😀
Schematic?
Thomas's Dac just arrived. I'm a novice. Can someone please email me a schematic? I'm using ~110-120V if that matters. Thanks 😉
Thomas's Dac just arrived. I'm a novice. Can someone please email me a schematic? I'm using ~110-120V if that matters. Thanks 😉
Mechanical Resonances
I'm glad I was able to provide some comic relief to Elso. I'm interested in learning how to reduce mechanical resonance when assembling this Dac. Peter Daniel linked to an article (see link below) with suggestions on how to reduce resonances when designing and assembling a component. Two of the ideas are:
1. Isolate transformers from chassis. I'm using Thomas's metal chassis. Is there any benefit to placing some type of damping material underneath each transformer? Any negative to just screwing the metal transformer to the metal chassis?
2. PCB Standoffs. The author suggests, where possible, to use brass screws instead of nylon standoffs. With Thomas's PCB, is there a risk that this would short the PCB, or cause a ground loop? As an alternative, ceramic spacers are suggested...although I don't know where I'd source those.
Link to full article: http://www.soundstage.com/maxdb/maxdb111998.htm
I'd appreciate any of your thoughts on this topic. Also, if someone has a schematic or zip file, could you please email to marvelli@hotmail.com. Thanks!
I'm glad I was able to provide some comic relief to Elso. I'm interested in learning how to reduce mechanical resonance when assembling this Dac. Peter Daniel linked to an article (see link below) with suggestions on how to reduce resonances when designing and assembling a component. Two of the ideas are:
1. Isolate transformers from chassis. I'm using Thomas's metal chassis. Is there any benefit to placing some type of damping material underneath each transformer? Any negative to just screwing the metal transformer to the metal chassis?
2. PCB Standoffs. The author suggests, where possible, to use brass screws instead of nylon standoffs. With Thomas's PCB, is there a risk that this would short the PCB, or cause a ground loop? As an alternative, ceramic spacers are suggested...although I don't know where I'd source those.
Link to full article: http://www.soundstage.com/maxdb/maxdb111998.htm
I'd appreciate any of your thoughts on this topic. Also, if someone has a schematic or zip file, could you please email to marvelli@hotmail.com. Thanks!
Re: Mechanical Resonances
Either tightly screw the PCB, I mean really tight, or hang the PCB loose in rubbers..........
riotubes said:
Either tightly screw the PCB, I mean really tight, or hang the PCB loose in rubbers..........
Ultimate Twin TDA1541a Non-oversampling DAC with tube buffer & reclock set...........
Hi Julien_M quantran,
Sorry to late visit the forum. I was handover the hand work of WTO operationto other dept already. I can spend more time for forum now.
TCXO was arrived. They were mita Made. 1.25 ppm.I will post to U asap.
BTW, the new Nano-amorphous pulse trans will post U one.
All the buyer for old DAC pls email to me. I will only collect the postage & free to upgrade for it.
I was checking the old thread will answer all the question today.
thx
thomas
Hi Julien_M quantran,
Sorry to late visit the forum. I was handover the hand work of WTO operationto other dept already. I can spend more time for forum now.
TCXO was arrived. They were mita Made. 1.25 ppm.I will post to U asap.
BTW, the new Nano-amorphous pulse trans will post U one.
All the buyer for old DAC pls email to me. I will only collect the postage & free to upgrade for it.
I was checking the old thread will answer all the question today.
thx
thomas
Ultimate Twin TDA1541a Non-oversampling DAC with tube buffer & reclock set...........
Hi kittikun,
do U made sure that the hum was coming from the power trans. Do you had some friends coming to hong kong.
I will take one to him for U. I got some 0.22 nippon steel lamination for new Power trans. Looks the noise will lower more with copper shield.
do u et the tcxo already. if not, pls let me know. I will follow with one new nano amorphous pulse to u. PE-65612 is not amorphous core. use magnet only. Now I use Nano will much better than stanard one.
thx
thomas
thx
thomas
Hi kittikun,
do U made sure that the hum was coming from the power trans. Do you had some friends coming to hong kong.
I will take one to him for U. I got some 0.22 nippon steel lamination for new Power trans. Looks the noise will lower more with copper shield.
do u et the tcxo already. if not, pls let me know. I will follow with one new nano amorphous pulse to u. PE-65612 is not amorphous core. use magnet only. Now I use Nano will much better than stanard one.
thx
thomas
thx
thomas
- Status
- Not open for further replies.