Eduard, what effect is there in the choke when there is lower than recommended current through it? Lower inductance?
Good news.
Doede, I only said to take it up with your credit card provider if AUDIO CREATIVE did not do anything. Kind of surprised you took that as an incendiary comment.
Oh, well ....
I just receive theyr email with apologize and VAT refound.
I think that they have a wrong calculation in theyr automatic system
Hi everyone, sorry of being out of topic! Is someone interested in buying my 4 stack DDAC1794? Full assembled and listened for 12 months. I´m selling it because i´ve switched to a DSP DAC. Anyway, the DDDAC1794 with cinemag 15/15B sounds terrific!
Here are the parts i want to sell altogether.
-DAC motherboard without SPDIF (red one) with a Belleson 5v 500mA regulator for digital
-4 DAC boards stacked
-2 power supplies, 12v and 5v from DDDAC
-no WaveIO, i will keep it
-2 cinemag 15/15B output transformers
-4 R-load wire wound resistors from rhopoint 0,1% GG102D
-2 AMRG Amtrans 12k bleeder resistors
-soldered with Mundorf silver/gold tin
Altogether i´ve spent 900€ for all parts an the kit. I would like to sell it for 750€+shipping costs, which is a fair price i think.
Please send me a PM if you´re interested in.
apoo
Here are the parts i want to sell altogether.
-DAC motherboard without SPDIF (red one) with a Belleson 5v 500mA regulator for digital
-4 DAC boards stacked
-2 power supplies, 12v and 5v from DDDAC
-no WaveIO, i will keep it
-2 cinemag 15/15B output transformers
-4 R-load wire wound resistors from rhopoint 0,1% GG102D
-2 AMRG Amtrans 12k bleeder resistors
-soldered with Mundorf silver/gold tin
Altogether i´ve spent 900€ for all parts an the kit. I would like to sell it for 750€+shipping costs, which is a fair price i think.
Please send me a PM if you´re interested in.
apoo
Hello,
A lower current will give a higher induction. With some chokes reduction in current gives a much higher induction. This depends on the design.
Sincere greetings, Edward
Coming back from holidays & found a pair of Lundahl's delivered at the neighbors. 
Inspired by James and Stefan, this is what I’m planning to build this coming weekend.
I think a 100Ohm bleeder will be plenty to load the chokes (initially in a standard serial configuration) and with less heat to dissipate, should not need a heat sink. I’m curious to see if my calculated output voltages will work out.
I'm planning to play with the cap values, so nothing set in stone, obviously.
Inspired by James and Stefan, this is what I’m planning to build this coming weekend.
I think a 100Ohm bleeder will be plenty to load the chokes (initially in a standard serial configuration) and with less heat to dissipate, should not need a heat sink. I’m curious to see if my calculated output voltages will work out.
I'm planning to play with the cap values, so nothing set in stone, obviously.
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Excellent discussion
Thanks for the intel Stijn. Will follow closely (assuming you'll be kind enough to share the outcome).
Incase anybody was still interested, I settled for a 2.5Kohm Z-foil shunt and a KHOZMO stepped 10K pot. A DDDAC 4 board stack seems to drive 2.5Kohm shunt easily with enough power in the bottom end left. My impression is that in particular the Z-foil shunt sound very good, very lucid/balanced and undistorted. It will take a long time for a the Takman Rex carbon resistors on the pot to burn in, so it’s full consistent potential will only reveal itself in due time. The Khozmo is expensive but its quality well worth it, imo.
Thanks, added a 50k Alps in the meantime, which is doing quite well surprisingly. Prior I had some plops etc, but gone now. Sound quality also decent. But will look into your option, although I am wondering if you considered a stepped attenuator given your expenditure as that was a step I was considering.
I had a cheap chinees stepped (balanced) rotary attenuator lying around and I tested with that but it wasn’t giving me much joy, I never got to fully understand why. I tried L-Pad and U-pad style shunt attenuation with a lot of different value shunt resistors ranging from 1K to 10K and found 2.5K was the sweetspot in combination with the input impedance of my amplifier, with regards to gain in combination with Bass output. There is a trade-off here, to little attenuation will give you to much gain and possible clipping and to high a shunt resistor value and the bass frequency will lose power/ impact (by what I was hearing).
In theory a shunt attenuator will influence the sound signature differently at different gain levels, due to the different impedance the dac will be seeing. But I found that when I used for example a 2.5k or a 5k shunt resistor, the audible difference was quite small,(i.e the DDDAC seems to be able to drive different loads quite well (1 or 4 boards will make a difference here)). Now if you plug in the number in the online calculator below you’ll find that with a logeritmic 48step attenuator, only at the last ¼ of the steps the impedance will rise significantly. Which for me was an acceptable compromise as I will be hardly using these steps.
http://rssconsultancy.co.uk/shunt.html
I have finally able to replicate Stefan's Unregulated PS. This is my first iteration, hence only cheapy Nippon 2200uf 35V (Japan made) were used. Once am able to finalise it, will have the bank of Solen film caps in place of electrolytic.
Since this is still a preliminary experimenting stage, appreciate your feedback if you could pick the abnormality?
Basically, I have 2x15V 200VA EI transformer going through the 1st Choke, output of the Choke into an array of 4 x 2200uf, the output is then into 2nd Choke which going to the last array 2x 2200uf. A 200R 12W Mills Wirewound resister is acting as bleeder. Somehow, I do not feel the heat other than a touch warm to touch.
Note I have both secondaries 15V output connecting in parallel. I was told parallel the secondary output will double the VA at same output voltage while in serious will double the voltage at same VA. Please correct me if my understanding is in correct?
Observation: I really like it!!! It reminded me of the KillerDAC sonic signature. Very mellow mid, the guitar, cello, and vocal are very real like an un-amplify concert. All the edginess seems dissipated. Sound are more 3D and bigger sound image than my setup was used to. The downside is the bass isn't as articulate nor forced. The bass impact seems loosen up, and sluggish. I think once the tent shunts are fitted, God knows if I will camp in my shed for life!
I have also did an unusual experiment to reassure myself that evenly distribute the DAC boards top and bottom of Mainboard for shortest i2s signal path will not yield the better sonic improvement despite previously reported here. Guess what?!? My findings concur with previous findings. Stacking DAC-boards top and bottom of the mainboard is A BIG NO NO...!
Note - I went even further by adding little film caps to very top and very bottom, and it still unsuccessful! I have since went back to my 11-decks tower. LoL!
Since this is still a preliminary experimenting stage, appreciate your feedback if you could pick the abnormality?
Basically, I have 2x15V 200VA EI transformer going through the 1st Choke, output of the Choke into an array of 4 x 2200uf, the output is then into 2nd Choke which going to the last array 2x 2200uf. A 200R 12W Mills Wirewound resister is acting as bleeder. Somehow, I do not feel the heat other than a touch warm to touch.
Note I have both secondaries 15V output connecting in parallel. I was told parallel the secondary output will double the VA at same output voltage while in serious will double the voltage at same VA. Please correct me if my understanding is in correct?
Observation: I really like it!!! It reminded me of the KillerDAC sonic signature. Very mellow mid, the guitar, cello, and vocal are very real like an un-amplify concert. All the edginess seems dissipated. Sound are more 3D and bigger sound image than my setup was used to. The downside is the bass isn't as articulate nor forced. The bass impact seems loosen up, and sluggish. I think once the tent shunts are fitted, God knows if I will camp in my shed for life!
I have also did an unusual experiment to reassure myself that evenly distribute the DAC boards top and bottom of Mainboard for shortest i2s signal path will not yield the better sonic improvement despite previously reported here. Guess what?!? My findings concur with previous findings. Stacking DAC-boards top and bottom of the mainboard is A BIG NO NO...!
Note - I went even further by adding little film caps to very top and very bottom, and it still unsuccessful! I have since went back to my 11-decks tower. LoL!
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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Great to hear that it's sounding nice, but I don't understand how you have wired your transformer secondaries and diodesI have finally able replicate Stefan's Unregulated PS. This is my first iteration, hence only cheapy Nippon 2200uf 35V (Japan made) were used. Once am able to finalise it, will have the bank of Solen film caps in place of electrolytic.
Since this is still a preliminary experimenting stage, appreciate your feedback if you could pick the abnormality?
Do you have a diagram?
In my choke power supply I run 'Full Wave rectification with centre tap' which can be achieved with 2 diodes and looks something like this.
So it's ok to join the 2 centre output wires of the transformer together before they reach your circuit, as they become the GND, but you have also joined your 2 outer wires together before they get to the diodes, and I don't think that's right.
I've changed stuff around since I did this, and it's a proper mess, but maybe here you can see the 2 blue wires coming from the transformer going into separate diodes into the first choke and the 2 brown wires for the centres of the secondary windings joining and becoming the gnd
hope that helps,
James
200R will only dissipate about 1 watt with your caps/voltage, so shouldn't get very warm.
www.nilno.com/docs/BleedRes.xls
@Chanh, what voltage is your PSU putting out, before connecting to the DAC and when connected? In your case with 2x15V transformer I would suspect the DC out to be quite high..
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....but I don't understand how you have wired your transformer secondaries and diodes
Do you have a diagram?
Have a look at the diagram in post #2307. That's how I'm doing it too.
Hi James,
I think with your configuration, lower output voltage transformer is needed. i.e below 12V?
My setup is based on diagram provided by PET-240 via email.
I think with your configuration, lower output voltage transformer is needed. i.e below 12V?
My setup is based on diagram provided by PET-240 via email.
An externally hosted image should be here but it was not working when we last tested it.
Hi stijn001,
It is currently outputting 13.4V with 15V secondary EI. Have asked Doede sometime back if 14V of a car battery would damage the stock regulators, and he replied "no".
My ps is very much similar to yours in post 2307, except no first stage filter capacitor and different chokes are used (mine are Valab).
Thanks,
Chanh
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Hello,
I am not sure if the bleeder will drain enough current to make it function like a true choke input. Usually the choke input will give lots of energy in the lower region.
of course having the cables much shorter might help too.
And you could try a common mode choke as input choke.
i will probably fet two different lundahls next week.
The shunt will also give an improvement.
Sincere greetings, edward
I am not sure if the bleeder will drain enough current to make it function like a true choke input. Usually the choke input will give lots of energy in the lower region.
of course having the cables much shorter might help too.
And you could try a common mode choke as input choke.
i will probably fet two different lundahls next week.
The shunt will also give an improvement.
Sincere greetings, edward
Hi Edward,
With 11-decks, I think they yield approx 1.2A plus bleeder resister. However, DAC will required approx 2.8-3A when fully shunt for 11-DAC boards. Is that sort of current adequately utilise my unregulated ps configuration?
You have mentioned the comon mode choke, is this applicable to only Lundahls? My Valab do not have common mode.
@James, grateful if you could pls PM or post the closeup pics of where your shunts are installed within? I have now dissembled my DAC boards and getting ready for the Tent Shunts. Hopefully am getting a response from Guido soon!
Many thanks.
With 11-decks, I think they yield approx 1.2A plus bleeder resister. However, DAC will required approx 2.8-3A when fully shunt for 11-DAC boards. Is that sort of current adequately utilise my unregulated ps configuration?
You have mentioned the comon mode choke, is this applicable to only Lundahls? My Valab do not have common mode.
@James, grateful if you could pls PM or post the closeup pics of where your shunts are installed within? I have now dissembled my DAC boards and getting ready for the Tent Shunts. Hopefully am getting a response from Guido soon!
An externally hosted image should be here but it was not working when we last tested it.
Many thanks.
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