Promitheus DAC anyone?

tanchiro58 · « **Reply #340 on:** 14 Jan 2009, 12:56 am »

Quote from: walkern on 14 Jan 2009, 12:48 am

Hey Tan (or anyone else with a manual handy),

I noticed that you reduced the output level of your DAC to 1 Volt. I just changed amps, and now one click up on my TVC and the volume is already pretty high. I'm too lazy to head to attic to try and find my owners manual for my DAC. Can you let me know how to set the jumpers so I am outputting 1 volt from my DAC?

Thanks,

Neil

Neil,

The jumpers are located before the op amps if you look at the front DAC. Just use a small tip pliers to lift them up then you put the jumpers to the left side of the three.

walkern · « **Reply #341 on:** 14 Jan 2009, 05:30 pm »

Thanks Tan! Will do.

Neil

flathead · « **Reply #342 on:** 21 Jan 2009, 04:10 am »

Thanks everyone for contributing to this thread. I have been looking for a DAC for the SqueezeBox Duet that I purchased recently. After extensive web research and reading all of the informative comments on this thread I just ordered the Promitheus DAC with the Burson op amp. I am really looking forward to receiving it.

tanchiro58 · « **Reply #343 on:** 21 Jan 2009, 12:55 pm »

Quote from: flathead on 21 Jan 2009, 04:10 am

Thanks everyone for contributing to this thread. I have been looking for a DAC for the SqueezeBox Duet that I purchased recently. After extensive web research and reading all of the informative comments on this thread I just ordered the Promitheus DAC with the Burson op amp. I am really looking forward to receiving it.

Flathead,

You will not regret after the DAC is breaking in. But if you have a chance to modify the Duet to a truly 75 Ohm SPDIF (RCA) output you will be more happy to listen to your music.

flathead · « **Reply #344 on:** 21 Jan 2009, 06:01 pm »

Thanks Tan!

I have been considering digital modifications for the Duet based on related comments. The Bolder Cable Company states the following for their 'Standard' digital modification for the Duet.

"We have come up with some changes to the internal parts that we feel improve the sound. We change the internal power supply reservoir capacitor to a higher quality item. We also remove everything in the digital signal path and run a 75 ohm coax direct to a WBT NextGen RCA. We have come up with some improvements based on our work on the RE-BOX project. We now including upgrades to the internal clock power supply."

I just e-mailed them to see if the mods to the internal clock power supply are included in this as they also have an 'Enthusiast' digital mod and it is difficult to tell what the difference is from the Standard mod.

The Standard mod is $200 USD and this seems reasonable given what appears to be included in the mod. Nonetheless I would like to keep the costs down if I can make some or most of these mods myself, particularly the changes required for the 75 Ohm SPDIF. I am a novice modifier and have only made one modification, a capacitor change in the Tice Power Block power conditioner. I am dangerous with a soldering iron, but I have the 'bug.'!

Can the modifications to the digital section of the Duet be done by a novice?

Thanks.

PS Tan - I really like the slide you have of the baby. What an expression! I have shown it to a hundred people.

tanchiro58 · « **Reply #345 on:** 21 Jan 2009, 06:45 pm »

Quote from: flathead on 21 Jan 2009, 06:01 pm

Thanks Tan!

I have been considering digital modifications for the Duet based on related comments. The Bolder Cable Company states the following for their 'Standard' digital modification for the Duet.

"We have come up with some changes to the internal parts that we feel improve the sound. We change the internal power supply reservoir capacitor to a higher quality item. We also remove everything in the digital signal path and run a 75 ohm coax direct to a WBT NextGen RCA. We have come up with some improvements based on our work on the RE-BOX project. We now including upgrades to the internal clock power supply."

I just e-mailed them to see if the mods to the internal clock power supply are included in this as they also have an 'Enthusiast' digital mod and it is difficult to tell what the difference is from the Standard mod.

The Standard mod is $200 USD and this seems reasonable given what appears to be included in the mod. Nonetheless I would like to keep the costs down if I can make some or most of these mods myself, particularly the changes required for the 75 Ohm SPDIF. I am a novice modifier and have only made one modification, a capacitor change in the Tice Power Block power conditioner. I am dangerous with a soldering iron, but I have the 'bug.'!

Can the modifications to the digital section of the Duet be done by a novice?

Thanks.

PS Tan - I really like the slide you have of the baby. What an expression! I have shown it to a hundred people.

Flathead,

I am not much different than a "novice modifier" and did all the mods by myself to the SB3 but not the Duet I used to own. I almost modified the Duet but finally did not and sold it ( I like a cool remote!). That is my starting point. As you know the most critical part is the output part at the chip but not the power supply since Pat (Art) had mentioned in other thread. If you want to do by yourself you should consult with him because I modified my SB3 based on his model. And the modification is actually an excellent idea to improve the digital output of the SB3 to any DAC with truly 75 Ohm IMO. You need to use an excellent 75 Ohm connectors and digital cable too.

Good luck,
Tan

flathead · « **Reply #346 on:** 22 Jan 2009, 01:34 am »

Thanks Tan, I will follow up on this thread. Started to do so just now.

Shogun · « **Reply #347 on:** 22 Jan 2009, 11:07 am »

Nicolas,

the Dac is alway on. If I`m not using it, how many watts does it draw?

thanks

PromitheusAudio · « **Reply #348 on:** 24 Jan 2009, 02:36 am »

Shogun
The dac draws 10watts when its on.
hope this helps

Thanks
Nicholas

walkern · « **Reply #349 on:** 28 Jan 2009, 02:46 pm »

Has anyone tried the GD Audio Discrete opamps? I just order two of their "Moon" model to substitute, and when I install them according to the instructions (minding the notch) I either get no sound (when I ground their ground leads to the chassis) or just clicking/ticking sounds if I leave them ungrounded (just plugged in). I contacted the manufacturer, and he confirmed that I had them installed correctly but had no idea why they didn't work. They are supposed to be fine with voltages ranging from 9V to 23V. Any suggestions would be much appreciated... and if anyone has tried any other op amp substitutions (besided the Bursons) that they love (just in case I can't get these to work) I'd love to hear about your experiences.

Neil

cjng74 · « **Reply #350 on:** 29 Jan 2009, 07:45 am »

My DAC

http://www.audiocircle.com/index.php?action=gallery;area=browse;album=1723

don't know how to add photo? anyone can help?

satfrat · « **Reply #351 on:** 29 Jan 2009, 07:52 am »

cjng74 · « **Reply #352 on:** 29 Jan 2009, 08:00 am »

Satfrat,
thanks.

satfrat · « **Reply #353 on:** 29 Jan 2009, 08:17 am »

Quote from: cjng74 on 29 Jan 2009, 08:00 am

Satfrat,
thanks.

Not a problem.

analogmart · « **Reply #354 on:** 29 Jan 2009, 10:40 am »

Hi walkern,
Actually, you can not put GD Audio Discrete opamps directly on PCB because its big base.
A small capacitor beside opamp connector will block your opamps, so it cannot firmly lock together.
You need extension cord (Audio GD has it) to solve this , or extend capacitor leg instead.
BTW, makes sure that you order "Single discrete opamp" not "Dual"
Mart,

tanchiro58 · « **Reply #355 on:** 29 Jan 2009, 12:20 pm »

Neil,

You also need to adjust the output dc voltages of the gd opamps to match with the opt i guess unless the gd opamps can automatically adjust themself?!

tanchiro58 · « **Reply #356 on:** 29 Jan 2009, 12:28 pm »

Quote from: cjng74 on 29 Jan 2009, 07:45 am

My DAC

http://www.audiocircle.com/index.php?action=gallery;area=browse;album=1723

don't know how to add photo? anyone can help?

How does your dac sound with those big O caps? Did you replace them in place of the two golden Phillip output caps? Looks interesting!

cjng74 · « **Reply #357 on:** 30 Jan 2009, 05:46 am »

i receive the DAC already with the caps installed. i am the 2nd owner. can't compare with the original spec. i enjoy the DAC very much.
compare to TDA 1541, it has more speed and dynamic. i guess Nich is quite familiar with the modification. may be he can add.

walkern · « **Reply #358 on:** 30 Jan 2009, 10:05 pm »

Hey Mart and Tan,

Thanks for the advice regarding the GD discrete modules. I'd gotten the correct units (singles) and the extensions so I could hook them up without having to mess with anything on the main board, but I was assuming the chassis was an ideal place to attach the white "ground" wires. Oops! Those need to be attached to the signal grounds coming off the board to (and then from) the transformers on the right side of the DAC. Once I got the grounds connected correctly the units work like a champ... and I agree with the others who have tried them... they are a very worthwhile upgrade. And they work wonderfully at the +12 and - 12 volts the DACs are preset to, so I didn't have to adjust the voltage to them (whew!).

Neil

adam2434 · « **Reply #359 on:** 6 Feb 2009, 05:00 pm »

Hi, first post here.

I’ve been following this thread for a while and received a Promitheus DAC earlier this week (used from original owner).

As several others have reported, mine also has a significant amount of hum/noise.

Has anyone with the hum/noise heard back from Promitheus on this, or resolved the issue in some other way?

Given that several folks are experiencing this, does this appear to be a design/quality issue with some units, or perhaps a part that gets easily damaged in shipping (mine was double-boxed and packed very well by the original owner, and I do not see any obvious internal damage)?

Here are my specific observations and things I tested:

The noise/hum is audible from my seat (3 meters from the speakers) when I pause my transport and when no track is playing, with the preamp’s volume at a moderate setting of around 9 o’clock. The noise/hum tracks with my preamp’s volume level.

The noise/hum is present when no digital cables are connected, as well as when a coax digital cable is connected. Interestingly, when no digital cables are connected there is a low hum and high whine from both the coax and BNC inputs. However, when a digital cable is connected to the coax input, the coax produces only the hum (no whine), but the BNC still produces the hum and whine.

In troubleshooting this, I tried all of the usual suspects – tried 2 different power cords, 2 different analog cables, 2 different AC circuits, moved the DAC to different locations, tried a cheater plug to lift the ground. Nothing had an impact on the noise/hum.

I also tried the various output voltage jumper positions. The noise/hum is present in all positions, but varies in relation to where the noise/hum becomes audible vs. preamp volume setting. The other thing I noticed is that the output voltage from my jumper settings does not appear to match what is in the manual. For example, the middle jumpers are the loudest on my unit, but according to the manual, the middle jumpers should be the middle (2v) output. Does this mean there is something wrong with my unit?

The one last thing I can think of to try is to get a RCA-BNC adapter and connect digital cables/sources to both digital inputs simultaneously. The thought here is to see if perhaps noise is entering the unused BNC input. I know this is a long shot.

I know that Nicholas from Promitheus posts on this thread, so I hope he (and others) will comment on this issue and how to resolve it.

I will also send Nicholas an email on this.

Thanks,

Adam