Promitheus DAC anyone?

highdfever · « **Reply #240 on:** 29 Jan 2008, 11:01 am »

Hi Tan,

Some more questions:

Some user claimed the performance of Burson discrete op-amp was not good (AD825 is even better) but the problem may be due to voltage supply issue. It claimed the voltage supply is at least 15v in order to optimise this op-amp to function normally. So have you checked if Promitheus DAC provide enough voltage to power the op-amp? (May be Nick can help to answer this question)

I am not technical guy, so if I need to modify the power supply of the DAC in order to change the Burson discrete op-amp, then I am not able to do it.

Have you tried different size of Caps ( from the website, 0.1v - 1v ). What will be the difference?

B. Rgds
Andis

tanchiro58 · « **Reply #241 on:** 29 Jan 2008, 11:15 am »

Quote from: highdfever on 29 Jan 2008, 11:01 am

Hi Tan,

Some more questions:

Some user claimed the performance of Burson discrete op-amp was not good (AD825 is even better) but the problem may be due to voltage supply issue. It claimed the voltage supply is at least 15v in order to optimise this op-amp to function normally. So have you checked if Promitheus DAC provide enough voltage to power the op-amp? (May be Nick can help to answer this question)

I am not technical guy, so if I need to modify the power supply of the DAC in order to change the Burson discrete op-amp, then I am not able to do it.

Have you tried different size of Caps ( from the website, 0.1v - 1v ). What will be the difference?

B. Rgds
Andis

Andis,

Nick said replacement of stock opamps with Burson is fine. I do not have problems at all and did not need to replace any caps for PS. I personally do not like the sound of AD825. Maybe the audio consulting opamps are good but I doubt it. You might look and compared them to Burson. However, I still love the sound of Burson opamps after breaking in.

Quote

http://www.referenceaudiomods.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=RAM&Category_Code=OPAMPS

highdfever · « **Reply #242 on:** 29 Jan 2008, 11:50 am »

Hi Tan

Have you tried different value of Caps ( 0.1uf - 1uf MKP across pin 4 and pin 7 as suggested ). What will be the difference?

Many Tks
Andis

tanchiro58 · « **Reply #243 on:** 29 Jan 2008, 12:09 pm »

Quote from: highdfever on 29 Jan 2008, 11:50 am

Hi Tan

Have you tried different value of Caps ( 0.1uf - 1uf MKP across pin 4 and pin 7 as suggested ). What will be the difference?

Many Tks
Andis

Andis,

Burson suggests 0.01mF which is a perfect value to bypass but you can try higher values. I do not have the high value caps in hand right now.

Tan

Milenko27 · « **Reply #244 on:** 29 Jan 2008, 05:55 pm »

Just got my dac today, and have played for some hours, well what can i say: i am actually speechless...
The Promitheus dac fitted my system like a glove, simply amazing, can hardly wait until the burn in is finished.
By the way, mine had black lid and bottom and also a green (power) and a red (lock?) leds..
Build quality was excellent, this just might be my best hifi buy ever

tanchiro58 · « **Reply #245 on:** 29 Jan 2008, 06:07 pm »

Quote from: Milenko27 on 29 Jan 2008, 05:55 pm

Just got my dac today, and have played for some hours, well what can i say: i am actually speechless...
The Promitheus dac fitted my system like a glove, simply amazing, can hardly wait until the burn in is finished.
By the way, mine had black lid and bottom and also a green (power) and a red (lock?) leds..
Build quality was excellent, this just might be my best hifi buy ever

Congrats to you.

Mine is the first version. Does your DAC have a wooden platform underneath the pcb? If you do not mind would you post some pictures of your Promitheus DAC? Thanks in advance.

Happy listening,

Tan

Milenko27 · « **Reply #246 on:** 29 Jan 2008, 06:27 pm »

Yes, it has a wooden platform under the pcb, and also a piece of wood under the two trans.. on the dacs right side.
Will try to take some photos...

PromitheusAudio · « **Reply #247 on:** 30 Jan 2008, 05:40 am »

Milenko
Good to hear you like the DAC

Tan and Andis

I check out the burson buffer posting of yours and would like to comment that our DAC allows up to +14.5Volts to -14.5 Volts. You would need to turn the potentiometer clockwise to turn up the voltage
Also the maximum voltage may not be fully regulated if your wall drops below 118Volts. To measure place the probe of the multimeter at pin 4 and pin7
Pin4 is the minus voltage
pin7 is the positive voltage
The opamp chips are fed with a double stage regulator that means its a LM317L into a BC556 pass transistor. Hence there more voltage drop than the conventional regulators but the sound is much better because it decouples the right and the left channel

Also there is another tweak i would like to tell is to adjust the voltage of the opamp. Normally we set them at 12volts. I find i like this combo best. IF you system is transparent enough, 11.5 volts the sound would be laidback full body but may lack dynamics. 12.5 volts the sound is more dynamic, thinner and 12 volts is what you hear at the moment. I like 12 volts best. Play around if you are in the state of being able to place the probe steady on the pins of the opamp. The DAC is transparent to show that every little voltage counts

CHeers
Nicholas

analogmart · « **Reply #248 on:** 30 Jan 2008, 06:45 am »

Hi Nick.
Is +/- 14.5V recommend for Burson? What about 230V country?
Regards,
Mart

tanchiro58 · « **Reply #249 on:** 30 Jan 2008, 10:41 am »

Quote

I check out the burson buffer posting of yours and would like to comment that our DAC allows up to +14.5Volts to -14.5 Volts. You would need to turn the potentiometer clockwise to turn up the voltage
Also the maximum voltage may not be fully regulated if your wall drops below 118Volts. To measure place the probe of the multimeter at pin 4 and pin7
Pin4 is the minus voltage
pin7 is the positive voltage
The opamp chips are fed with a double stage regulator that means its a LM317L into a BC556 pass transistor. Hence there more voltage drop than the conventional regulators but the sound is much better because it decouples the right and the left channel

Also there is another tweak i would like to tell is to adjust the voltage of the opamp. Normally we set them at 12volts. I find i like this combo best. IF you system is transparent enough, 11.5 volts the sound would be laidback full body but may lack dynamics. 12.5 volts the sound is more dynamic, thinner and 12 volts is what you hear at the moment. I like 12 volts best. Play around if you are in the state of being able to place the probe steady on the pins of the opamp. The DAC is transparent to show that every little voltage counts

Nick,

I have steadily measured at pin4 and pin7 and see that it has 23.45VDC on the left and 22.74VDC on the right. Why the numbers are higher than your suggestion 12VDC? But the sound has body, transparent and dynamic. I set at 2dB. Any comments? Thanks.

Tan

PromitheusAudio · « **Reply #250 on:** 30 Jan 2008, 10:51 am »

Tan
sorry forgot to write it should pin4 with reference to ground
and pin7 reference to ground

IN your case you would need to retune the voltage because of the burson opamp slightly different current draw hence the voltages are not equal as we set for our opamp 5534

Cheers
NIcholas

tanchiro58 · « **Reply #251 on:** 30 Jan 2008, 11:01 am »

Nick,

How do I retune to match the Burson opamp voltage with the DAC voltage? Thanks for help.

Tan

anthony a. · « **Reply #252 on:** 30 Jan 2008, 09:01 pm »

Quote from: Milenko27 on 29 Jan 2008, 05:55 pm

Just got my dac today, and have played for some hours, well what can i say: i am actually speechless...
The Promitheus dac fitted my system like a glove, simply amazing, can hardly wait until the burn in is finished.
By the way, mine had black lid and bottom and also a green (power) and a red (lock?) leds..
Build quality was excellent, this just might be my best hifi buy ever

wow, you got your dac pretty quickly. good news. i still haven't had a chance to order one, i was in the middle of moving homes during christmas and still have too many boxes to unbox and organize before i can start enjoying audio again. did you get the silver pulse transformer upgrade? can anyone comment if there is a significant improvement by going with it?

Milenko27 · « **Reply #253 on:** 30 Jan 2008, 10:03 pm »

Anthony:
Yes, i got the silver pulse transformer upgrade. The dac sounds amazing and is getting better and better every minute. I hear details in my cds now that were drowned on my cd player which actually is not bad at all (thule spirit 150b). Heard the soundtrack from Pearl harbour today and i could literally pick out layer upon layer in the music, amazing details and still no digital hizz of anykind. It is just warm and musical with all the details. Some of the singers you can hear breathing and some f.ex. Bruce Springsteen has a much more "rusty" and natural voice than before, and...i could go on and on...simply stunning.

Tan:
Will try to post some pictures tomorrow, been busy working, listening to music, playing with my little daughter and so on.

Will like to add a big thank you to everyone who has posted in this tread which helped me to make the right decision.

Also a huge thank you to Nicholas Chua for truly making a fantastic dac at an amazing low price.
I will definately check out your pre-/power amps when it is time to upgrade again.

Sincerly:
Svein

ktfoo · « **Reply #254 on:** 31 Jan 2008, 03:47 am »

Hi, I'am new to this forum, have just received my dac from Nick two days ago and have started using it with my existing system....the sound from this dac was really good....it has a detailed, layered, warm and musical sound....will have to let it break in until it reaches 100hrs to see how much improvement the sound can be!....all in all its a good dac and value for money too.

Milenko27 · « **Reply #255 on:** 6 Feb 2008, 10:00 pm »

Tan: sorry for the pictures delay, my whole family has been sick so....
But now we are much better

Here are the pictures of my Promitheus dac:

First time posting pictures in the forum, hope they are ok.

tanchiro58 · « **Reply #256 on:** 7 Feb 2008, 01:39 am »

Milenko27,

Thanks for nice pics.

I also did the same as Nick about the wooden platform underneath pcb. I will place the ebony wood underneath the PS tranny and output trannies soon. Let see how is the sound improved.

Regards,
Tan

djwilbourn · « **Reply #257 on:** 19 Feb 2008, 01:27 pm »

hey guys,
new to this forum but considering the dac. i wondered how this dac stacks up specifically with the mhdt labs constantine. could someone offer a detailed comparison. thanks

tanchiro58 · « **Reply #258 on:** 19 Feb 2008, 06:30 pm »

Quote from: djwilbourn on 19 Feb 2008, 01:27 pm

hey guys,
new to this forum but considering the dac. i wondered how this dac stacks up specifically with the mhdt labs constantine. could someone offer a detailed comparison. thanks

IMO I have own the modded Promitheus DAC and modded MHDT Renaissance II DAC (same circuit as Paradisea with toroidal transformer PS). I would prefer the Promitheus DAC in my system with some tweaks. Good luck.

highdfever · « **Reply #259 on:** 2 Mar 2008, 05:19 am »

Hi Tan,

Burson replied me that they are out of stock now. I was told by other that this Opamp was not actually made by Burson, it was orginally made by a China company but has stop the production now. Burson has bought all the remaining stocks at that time.

Not sure if it is true or not but in case there is no more Burson Opamp. Would BB627 the best alternative. What will you recommend?

Rgds
Andis