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Upgraded Single Board PCM1794 NOS DDDAC
Upgraded Single Board PCM1794 NOS DDDAC
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Old 2nd December 2014, 10:38 PM   #21
rickmcinnis is offline rickmcinnis  United States
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Join Date: Jun 2006
nige2000,

Since this seems like a good place to discuss your battery scheme - I have a question.

I am going to try Zen Mod's CCS along with carlsor's.

I have found a nimh battery in a 9 volt format to use for the negative supply.

Could one use the same "charger" for this battery? Of course, with the leads oriented correctly.

Can you think of a reason to NOT to do this?
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Old 4th December 2014, 04:47 AM   #22
PET240 is offline PET240  Australia
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Location: Brisbane Northside
Hey Rick,

What voltages are the other batteries in use and what charge voltage is the "charger"?

Chuz,

Drew.
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Old 4th December 2014, 05:07 AM   #23
nokin is offline nokin  Viet Nam
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I've measured the current feeds 2 boards,
Receiver board # 70mA
Dac board # 60mA
So we can use any super shunt reg power in 100mA ccs range for each board.
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Old 4th December 2014, 02:00 PM   #24
juancho is offline juancho  United Kingdom
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Location: London, England
Quote:
Originally Posted by nokin View Post
I've measured the current feeds 2 boards,
Receiver board # 70mA
Dac board # 60mA
So we can use any super shunt reg power in 100mA ccs range for each board.
No, you can't. I split my analogue and digital supplies. Both analogue and digital used Belleson super SPM super regs rated at 225ma. But the analogue ones failed quickly, Belleson say because the switch on transient with 4 x 47uf would be close to their limits even tho by my calculations the transient shouldn't exceed around 180ma.........Anyway, the normal 0.5a rated ones work perfectly which Belleson kindly substituted
David
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Old 4th December 2014, 03:29 PM   #25
rickmcinnis is offline rickmcinnis  United States
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Quote:
Originally Posted by PET-240 View Post
Hey Rick,

What voltages are the other batteries in use and what charge voltage is the "charger"?

Chuz,

Drew.
nige2000 came up with a version of a scheme used by an Irish DAC to power his computer with the A123 3.3 volts batteries. The charger is a power supply for each voltage needed. For the computer 3.3, 5 and 12 volts. The batteries are constantly being charged when in use, I presume the batteries are acting as giant FAST capacitors in the this application.

Not knowing the provenance of the idea I thought this would be a great way to power the DDDAC. With advice from nige2000 I am using a single battery pack consisting of three cells for the 8 volts analog and a single cells for the 3.3 volts digital. I had intended to use a pack for each channel but nige2000 thought that would be ludicrous. Considering four of these batteries in series can start a car I figured he was correct. Certainly the best best way to begin.

Now with using the blue mainboard I want to use 5 volts for this. So another pack of two cells will be needed to power this. I will be powering WAVE IO with a separate pack of two cells since I think it is worthwhile to keep WAVE IO completely separate from the DAC,

Building a pair of Zen Mods CCSs which require a negative power supply. Easy enough to get the +8 volts from the regular supply. For the negative I am using a 9 volts package NIMH battery. My intention is to use the same charger for the -8 volts but with the leads from the "charger" arranged appropriately to this battery.

I cannot think of a reason this would not be OK but wanted some confirmation.

Using batteries allows getting rid of most of the components off of the DAC board. nige2000 has found caps, even by-pass caps, are not needed - disadvantageous, even.

Using my favorite wood for audio projects, balsa, I have made a three tiered
assembly above the main board to hold the batteries and the switches. Supply wire lengths are minimal and disassembly is fairy easy.

ALL grounds from the DAC are attached to one side of a SPDT switch; all grounds from the batteries are attached to the other. This turns everything on at one time. WAVE IO has its own switch, of course.

The "charger" power supplies are kept a distance from the DAC assembly. Another switch is needed to keep the batteries from discharging when the DAC is not in use. Again, I am tying all of the ground lines together at the switch.

Using my BELLESON regs for the "chargers". 8, 3.3 and 5 volts.

I probably did not make it clear that the chargers keep the batteries at the voltage needed. They are not fully charging the batteries which would blow the DAC up! No need for a regulator after the batteries.

nige2000 says he has listened with the "chargers" not attached (now, he is speaking of a computer setup using lower quality regulators) and hears no difference in the sound.

Yes, it does almost sound too good to be true.
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Old 5th December 2014, 01:04 AM   #26
nokin is offline nokin  Viet Nam
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Does anybody here not use the kit from dddac.com but re-layout and diy following pdf guidance file ?
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Old 5th December 2014, 03:44 PM   #27
rickmcinnis is offline rickmcinnis  United States
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I tried doing this with the DAC part but since I am an absolute ZERO when it comes to SMD solderng I gave up.

AS few of the parts as I retain I thought it would make for a more elegant installation. Oh, well ...

AS you can imagine there is not a chance I would try to mimic the mainboard!
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Old 5th December 2014, 05:04 PM   #28
nokin is offline nokin  Viet Nam
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Ssop28 package like wm8805 and pcm179x is a little bit of hard to work with soldering, but for 74vhc series it is easy for you to do. You can use the magnifier to complete them.
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Old 5th December 2014, 07:22 PM   #29
rickmcinnis is offline rickmcinnis  United States
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Join Date: Jun 2006
Quote:
Originally Posted by nokin View Post
Ssop28 package like wm8805 and pcm179x is a little bit of hard to work with soldering, but for 74vhc series it is easy for you to do. You can use the magnifier to complete them.
You are kind to be encouraging!

I think I do a good job of soldering but have never successfully soldered an SMD device. Of course, practice would improve my efforts but at the cost of PCM1794s ... No question those 74vhcs are a better/cheaper device to practice with!

Take care,
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Old 6th December 2014, 12:54 AM   #30
nokin is offline nokin  Viet Nam
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My exps. for SSOP28 package :
- Put IC on the board and align its pin and pad,
- Make 2 soldering points on pin 1 and 15 to fix the chip
- Use small piece of heatsink for chip and hold it by one hand, soldering by other hand.
- Finish soldering job pin by pin, by squeezing solder tip for each pin from chip's edge side.
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