A NOS 192/24 DAC with the PCM1794 (and WaveIO USB input)

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#2,221
eduard said:
Hello,
The late Allen Wright did describe the choke as an electronic or electric? flywheel. Like a kind of energy storage devive.
If i am right when you double the voltage with the same capacity you will end up with four times the energy.
Tube circuits are high impedance circuits so usually the power supply will have a lower impedance even when using chokes.
The currents with solid state are bigger and solid state have lower impedance so there the tube circuit has some advantages.
Usually my experience with choke inputs is like very easy, powerfull, melodic.
I remember reading that the same transformer can supply about 30% more current with a choke input compared to cap input.
Supersurfer, If you wanna try a 10+5 v 4A with primary and secundary coils next to each other you can lend one of mine. You might be able to use the raise induction
Sincere greetings, Edward
Click to expand...

Hi Edward,

I think you mean current instead of voltage? A chokes inductance is generated by the current in the windings, not voltage.

I would be interested in trying your trannie. I will send you pm.

Regards,
 
#2,222
Hello Supersurfer and the others,
Wich cap input there will be higher current pulses and with choke input there will be a constant but lower current flowing which will result in a lower temperature rise.
Sometimes you will the current rating with cap and choke input mentioned on old transformers.
Sincere greetings, Edward
 
#2,223
lipo battery psu

hi all,

wir are discussing and evaluating different psu with relatively expensive main transformers and chokes exceeding easily 200 euro budget which i am sure improve the sound quality.
however, why not using a relative cheap lipo battery for a fraction of the costs instead which may deliver even a better sound quality (???). has someone tried that and could compare to the choke psu?

here i found 12v lipo offers of 6800ah battery packs incl. charger which should guaranty several hours of enjoying music with the dddac for just 20 euro!
Rechargeable Li Po BATTERY12V DC Multipurpose Batteries for CCTV Cam 6800mAh WK | eBay

oder

DC 12V Super Rechargeable Lithium ion Battery Energy Storage Pack 6800mAh | eBay

i have ordered one of them and will compare that to my modified standard dddac psu as soon as i have received and tested it.

regards
 
#2,224
Hello,
I have been using choke inputs for a long time. 2 years ago i did buy a class D amp in the USA that did come without a power supply. So i did use some spare parts and some new ones ( panasonic caps) to make a choke input. Recently i did switch to battery supply much better.
BUT some people did try batteries with the dac and other supplies were better. So that is why i did start talking about choke input after reading about the chokes Supersurfer is using in a cap input power supply. NOW he also did switch to choke input!!!
There is a story about a pair of big batteries melted together probably because of a charger going wrong. I would stick with brand name chargers and batteries.
Chokes have infinite lifetime so they are not that expensive. For 40 euro you can buy 120 va R core in france. If you use one dac board with no shunts current will not be that big and you could use another choke with less current rating that will be easier to find. I might have one lying around.
We will wait for your results with the batteries.
Sincere greetings, Edward
 
#2,225
If you are not familiar with Lipo safety please take time to read about charging and the potential fire hazard these batteries can pose if mishandled.

Here is a massive thread on lipo safety, lots to read...

Complete Guide to Lithium Polymer Batteries and LiPo Failure Reports - RC Groups


For a shorter more dramatic example of what can happen look on You Tube for lipo fires.

Of course there are thousands in use daily with no problem but be careful handling and charging them.
 
#2,226
mr_whocares said:
here i found 12v lipo offers of 6800ah battery packs incl. charger
Click to expand...
HI. I have no experience with using these battery packs, but in other threads (search Ian's FIFO thread I think) there's posts indicating that the charge balancing and overcharge protection circuits that are embedded in these battery packs produce a lot of noise. It may be ok for a dac power supply but some found it was too noisy for a clock power supply. In Ian's case he built a "charge manager" board that allows using just the batteries with a separate charger/load balancer/protector. The "battery manager" is just a relay that switches between input/output of the battery to the clock when the dac is turned on and to the charger circuit when the dac is off. That way the noisy electronics are out of the way when the battery is powering the clock. Please do report on your findings after you test it!
 
#2,228
palmito said:
HI. I have no experience with using these battery packs, but in other threads (search Ian's FIFO thread I think) there's posts indicating that the charge balancing and overcharge protection circuits that are embedded in these battery packs produce a lot of noise. It may be ok for a dac power supply but some found it was too noisy for a clock power supply. In Ian's case he built a "charge manager" board that allows using just the batteries with a separate charger/load balancer/protector. The "battery manager" is just a relay that switches between input/output of the battery to the clock when the dac is turned on and to the charger circuit when the dac is off. That way the noisy electronics are out of the way when the battery is powering the clock. Please do report on your findings after you test it!
Click to expand...

im testing two lifepo4 cells on float charge by 2 linear supplies, bypassed the lf80 an lf33 similar to what the guys are doing with the shunts
results look promising

the problem with the battery packs is the battery management circuitry.

will report back when i get a bit further on
 
#2,230
Hello,
Some more food for thought on power supply.
If you decide to go for an R core transformer and you would need 18 volt ac because of choke input. There are two 300VA models availabe. Two secundairies 18 volts and put them in parallel are two 9 volts and put them in series. The current rating will be the same but there might be some other things to consider????
Lundahl also has a 400mH 1.7A 3,4 ohm(LL2733 2 windings in series) Seize is a little big bigger. Price too but what about sonic benefits?
Did find some R core 2 times 20mH common mode chokes for 2.5A . Dont know series resistance but will be lower than the big inductance types. For the price of the ll1694 you can buy 3 of these.
Maybe the 400mH as a choke input common mode , then a cap, then a LL1694, some more caps. Stefan ( supersurfer) did add an extra filter ( rc with a resistor). Could be choke too if you have some chokes lying around at home. Just tell us the current rating.
Sincere greetings, Edward
 
#2,231
After some hours enjoying capacitor input with chokes, I've wired the chokes correctly and made a choke input : back to 2*15V secondaries, 2 chokes, 2*4400µF and 75 Ohm bleeder.
I have 14.5V at the bleeder sides.

The first hour of listening gave more meaty tones, a more open and spacious sound, and a more coherent presentation. Details are tones are even more natural and convincing, so this is one more setp toward analog music.

I still have some serious modifications to do on the DAC deck, but the system is a killer as is.
 
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#2,232
G600 said:
After some hours enjoying capacitor input with chokes, I've wired the chokes correctly and made a choke input : back to 2*12V secondaries, 2 chokes, 2*4400µF and 75 Ohm bleeder.
I have 14.5V at the bleeder sides.

The first hour of listening gave more meaty tones, a more open and spacious sound, and a more coherent presentation. Details are tones are even more natural and convincing, so this is one more setp toward analog music.

I still have some serious modifications to do on the DAC deck, but the system is a killer as is.
Click to expand...
excellent feedback, thanks 🙂
Changing back to a 12v transformer and choke input is next on my to-do list. When I tried it previously, I didn't have the chokes wired correctly.
Hopefully I can find the time this week 🙂
 
#2,234
Seeking advice for Shunt regulators with 11-DAC boards

Hi Gents,

Has any one tried beyond 8 decks? I am going to extend my 8 decks to 11 decks so I can precisely making use of AN Tantalum 12R I/V resister(s). Not sure how much improvement I could yield from increase another three more boards? Furthermore, I am also contemplating to have the 11-decks boards and mainboard mod with 47 Shunt Regulators. Will the unregulated chokes(R23, 50mH at 5A) input PS with 200VA EI transformer be sufficient?

Please share your thoughts/advices, especially with the Shunt regulators as I have concerns with this massive investment against my expectation!

Regards,
Chanh
 
#2,236
I found jumping from 4 to 8 has more refined. We experimented my 8-decks vs a friend's 4-decks on several occasions and at both in my setup and a friend setup. We both concur 8-decks sound better. However, we both are a little doubt if the addition 3 is as noticeable?

Nonetheless, my view is 4 to 8 most definitely worth it. 😉

Best,
Chanh
 
#2,238
I have wondered if an odd number of decks could be better.

Might be interesting to listen to seven and hear if there is a difference.

Still wonder about choke input for the digital section of the chip.

Has anyone using a choke input on the digital side noticed a diminution of dynamics? This is what I would worry about but, of course, that does not mean it will happen.
 
#2,239
I am coming back with one more question. I see that there is difference in circuits of dac modules for mainboard with spdif dddac 1794s and without - dddac 1794. I circuits that I downloaded, resistor that is on data output of dac chip is 100R in first case and 1k in second (R7&9). I received motherboard without spdif and dac module of new version - 100R resistor.
What should I do? Follow old schematics and solder 1k resistors or follow new one and solder 100R that I recieved with board? I see that circuits of both motherboards differ and I don't want to fry anything. Difference in resistance is quite significant. 😕
 
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