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Old 8th November 2010, 02:14 AM   #621
qusp is offline qusp  Australia
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because thats all he bought, if he sells you just the parts, then he will have a board but not parts. as he explains he only bought enough parts for the number of boards he has
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Old 8th November 2010, 03:09 AM   #622
pidesd is offline pidesd  Canada
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what i want to know is: why did he not order kits for those who wanted kits and boards for those who wanted boards? i mean if i wanted a kit i had to want a board, right?

and let me just say i m not angry at all , just in case anyone would think so

i m just confused .

Last edited by pidesd; 8th November 2010 at 03:27 AM.
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Old 8th November 2010, 08:08 AM   #623
qusp is offline qusp  Australia
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ooh I dunno, maybe because it was easier to just order sets of everything so that when people just drop out without arranging someone to take their place, which lets just say is not unusual, he would not be stuck with just a set of parts, or just a board to find a home for. I really do not think that there are any grounds for questioning someone who put 2000 out of his own pocket to cover this for everyone. then of course the time spent on design, testing and now support.
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Old 8th November 2010, 09:45 AM   #624
qusp is offline qusp  Australia
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the above wasnt meant to sound as harsh as what it reads, and not directed at anyone in particular, but lets just say I get why people arent always that keen to get involved. most were excellent, so its not a sweeping statement and I do get that **** happens, just guys, leaving things to the last minute is not fair given the amount of warning

BTW I found the heatsinks needed at conrad if anyone is keen on adding them, it will increase shipping costs a bit, but the sink itself is pretty reasonable.

Last edited by qusp; 8th November 2010 at 09:47 AM.
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Old 8th November 2010, 11:17 AM   #625
NicMac is offline NicMac  Italy
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Default Rail voltage and current draw

Is 45VDC regulated still true in the final circuit? What is the current draw of the I/V rails at this DC voltage? Thanks!
Nic
Quote:
Originally Posted by opc View Post
Hi Guys,
- Transformers from Antek:
Antek - AN-0240
They're $11 each - 2 x 38.4VAC with 480mA current draw, which should give about 53.5VDC. I'm using +/- 45VDC regulated which is about perfect. You could probably get away with +/-50VDC as well. They're 25VA, and the circuit needs about 21VA. I don't like over-sizing transformers for low level circuitry, so I'd rather be at 84% capacity with a 25VA than 42% with a 50VA. Any comments here are welcome, and there is a 50VA version for $13 if people prefer that.
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Old 8th November 2010, 03:24 PM   #626
qusp is offline qusp  Australia
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haha my only comment is i'm glad I got chunky heatsinks coming. I specified the 90va center tapped +/-45vac secondary for mine to allow me to use it with other circuits if need be. so i'll be running +/-50v again. I got a custom potted sumR trannie with 2 x center tapped 25vac secondaries @ 1A and the center tapped 45vac @2A for a total of 140va.

its a bit of a monster for a DAC. Richard was kind enough to put 18AWG solid core copper leadouts on it for my own peace of mind.

so going by the above the new design layout is roughly the same, except i'll have more current to burn as I dont need to account for so many regulators voltage drop. although i'm sure my minigold isnt anywhere near as efficient as the ICs.

apparently my salas shunts are on the way also
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Old 9th November 2010, 05:45 AM   #627
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Quote:
Originally Posted by qusp View Post
haha my only comment is i'm glad I got chunky heatsinks coming. I specified the 90va center tapped +/-45vac secondary for mine to allow me to use it with other circuits if need be. so i'll be running +/-50v again. I got a custom potted sumR trannie with 2 x center tapped 25vac secondaries @ 1A and the center tapped 45vac @2A for a total of 140va.

its a bit of a monster for a DAC. Richard was kind enough to put 18AWG solid core copper leadouts on it for my own peace of mind.

so going by the above the new design layout is roughly the same, except i'll have more current to burn as I dont need to account for so many regulators voltage drop. although i'm sure my minigold isnt anywhere near as efficient as the ICs.

apparently my salas shunts are on the way also
Do you plan to power the buffalo with the Salas shunt ?

D.
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Old 9th November 2010, 05:47 AM   #628
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I am quite lost in this thread. Is it possible to use this circuit/board for a dual mono DAC configuration ? Does it have only Balanced out or also unbalanced ?

Thanks,

D.
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Old 9th November 2010, 10:03 AM   #629
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Quote:
Originally Posted by Nikon1975 View Post
I am quite lost in this thread. Is it possible to use this circuit/board for a dual mono DAC configuration ? Does it have only Balanced out or also unbalanced ?

Thanks,

D.

Better use a balanced/unbalanced like the TP Ballsie Filter/Buffer to get full potential.
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Old 10th November 2010, 01:48 PM   #630
opc is offline opc  Canada
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Hi Guys,

Well, the additional caps arrived yesterday, and I finished the kits late last night. I'll start shipping this evening, so the first 10-20 people who paid should see their board ship today.

pidesd:

I made an announcement several pages back that because there was an equal number of boards and kits (I wrongly assumed that everyone with a board wanted a kit to go with it) it would be easier to just sell them as a set.

I actually have no idea what you would want with just the SMD parts? The only use I can see would be if you're etching your own board with exactly the same layout. If that's the case, then take it from someone who has etched dozens of his own boards: it's easier, cheaper, and better to just get them made professionally. I can promise you that making your own will cost you significantly more than $20.

Anyhow, unless someone here wants just a board without parts, then I'm not willing to separate them. I'll ask those on the waiting list, and we'll see what happens.

NicMac:

My plan is to use +/-45VDC, and that's more or less what the board is designed for. You can use up to +/-50VDC, or down to whatever voltage you want. I saw a steady decrease in distortion as voltage was increased, but distortion started to increase again above +/-45VDC. Performance was slightly worse at +/-50VDC, and when you factor in the added dissipation, I see no reason to use anything other than +/-45V unless power dissipation is a problem and you're willing to give up performance in exchange for running lower rails. I posted some THD+N curves at different voltage levels to show this somewhere earlier in the thread. +/-45VDC is what Nelson would call "The sweet spot" for this particular circuit.

You'll see between 110 and 120mA of current draw from each leg with +/-45VDC. That means each channel will draw about 230mA total from the regs.

Nikon1975:

I know this thread has become a little unruly (I should have split the GB stuff into a separate thread) but all you really need to do is read the first 15-20 pages or so.

The balanced vs. SE question has been asked and answered at least a dozen times, and there are even measurements to show you what you can expect.

As for dual mono, it would certainly be possible, but you'll need four BAL/SE converters, one for each output on two boards. Then you'd get dual mono balanced output.

One thing I forgot to mention, and that I noticed the other day, is that if you use this circuit in SE mode by just taking the positive output to ground, then you WILL get clicks and pops on power up and power down. The circuit relies on the CMRR of the next stage to reduce clicks and pops on power up/power down.

I tested it plugged directly into an Anthem A2 amplifier (balanced input with 36dB of gain) and there was very minimal clicks on power up, and nothing on power down. With just a SE RCA output though, there was a very significant pop on startup and shutdown. For this reason, I strongly suggest a proper BAL/SE converter which is what I've been saying all along.

Regards,
Owen

Last edited by opc; 10th November 2010 at 01:51 PM.
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