Help me decide which ebay dac please?

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pre65
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#331

Post by pre65 »

Ali Tait wrote:Nick, I wonder if that's the problem with mine? What's the mains voltage at your place?
Ali, stick your DMM on the transformer 15V ac outlets and see if you are getting 15V.

Since I resistored mine down to 15V the regs don't get so hot.
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Nick
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#332

Post by Nick »

Ali Tait wrote:Nick, I wonder if that's the problem with mine? What's the mains voltage at your place?
235v normally.
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Paul Barker
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#333

Post by Paul Barker »

colin.hepburn wrote:OK so finally got my AK4396 DAC and going to get a pair of Toroidal transformers from rapid
So just want to check I have this right the regulators are 12 volt and 9 volt so
So for the 12 volt regs one 50VA 0-15-0-15 and one 50 VA 06-0-06 wired in series see link for TX wiring http://solderman.dapj.com/2005/09/trans ... allel.html
I would order 12 0 12 and 6 0 6 my little Talemas are that and no issues at all. Also 50 VA is overkill and will create problems of over voltage for you. A small toroid is given a 10% underwind of the primary to account for regulation. Regulation is the factor applied to take into account the iron and copper parasitic losses. So if you don't draw the full 50 watts your secondary voltage will be up to 10% too high. furthermore if it is wound for 230v your secondary would likely be high unl;ess you live in London in which case it will be low one minute and high the next.
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colin.hepburn
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#334

Post by colin.hepburn »

Paul Barker wrote:
colin.hepburn wrote:OK so finally got my AK4396 DAC and going to get a pair of Toroidal transformers from rapid
So just want to check I have this right the regulators are 12 volt and 9 volt so
So for the 12 volt regs one 50VA 0-15-0-15 and one 50 VA 06-0-06 wired in series see link for TX wiring http://solderman.dapj.com/2005/09/trans ... allel.html
I would order 12 0 12 and 6 0 6 my little Talemas are that and no issues at all. Also 50 VA is overkill and will create problems of over voltage for you. A small toroid is given a 10% underwind of the primary to account for regulation. Regulation is the factor applied to take into account the iron and copper parasitic losses. So if you don't draw the full 50 watts your secondary voltage will be up to 10% too high. furthermore if it is wound for 230v your secondary would likely be high unl;ess you live in London in which case it will be low one minute and high the next.
Right I was going by the print on the dac for 9 to 15volts and 13 to 15 volts and allowing for regulator drop out the VA Rating is me I always use bigger than is needed well in solid-state Amp so thought it was ok for the dac as well my Main Voltage is always a good 241 volts
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al newall
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#335

Post by al newall »

I use 2x 12v transformers and my mains is always above 240v.
No problems so far.
Much to learn there is.
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colin.hepburn
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#336

Post by colin.hepburn »

I was just going by what i read somewhere about regulator Drop out think thats why the 3 volts over came in
Plus I reminder reading on the other WD forum about this some have had this problem with dropout on the WAD phono so must depend on your main voltage if it drop off
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Ali Tait
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#337

Post by Ali Tait »

Nick wrote:
Ali Tait wrote:Nick, I wonder if that's the problem with mine? What's the mains voltage at your place?
235v normally.
Not that I'm questioning your thoroughness, but if you measured how it was doing with that voltage, I wonder if the slightly higher voltage I have here would be enough to upset the reg? Normally runs at 240-243 here. I haven't checked the secondary voltages yet, I can do so tomorrow. Whaddaya reckon?
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Nick
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#338

Post by Nick »

Everything is possible. I still suspect damaged the dac or it was naff to start with. But hard to say. Having said that you found it was running hot. I found it warm, but not hot, so maybe thats part of it.
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Ali Tait
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#339

Post by Ali Tait »

I suspect you are correct also, but it sounds bloody good when it's behaving itself. I think I'll order another built one to compare with the other I'll build with boteek bits. It'll.serve to see if I've wasted money on better components if nothing else.
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Nick
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#340

Post by Nick »

Yep, I can send you the stock board for comparison if you like.
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Ali Tait
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#341

Post by Ali Tait »

Yes please Nick, that would be helpful.
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Ali Tait
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#342

Post by Ali Tait »

The board had arrived, so when I got home earlier I fitted it. Distortion seems to be gone I think, the only problem is it now sounds pants compared to how it did before, and I seem to catch a little glimpse now and again of a little distortion, but it may be it's just sounding glassy as it needs to run in. Again!

I have fitted 100R padding resistors as you suggested Nick, and the voltage at the terminals is just over 15v. I will go to Maplin tomorrow and get a higher value so as to get it under the 15 mark.

We'll see how it goes running in.
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Ali Tait
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#343

Post by Ali Tait »

Interestingly, all three boards have different caps on. Guess they just fit what they have.
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Nick
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#344

Post by Nick »

One of the cap that came with the 96 board I built was crap so I put one out of the parts box in.

Next week or whenever you are away again, send the DAC (and the 96 board) to me Ali and I will see if I can get to the bottom of whats going on.
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Ali Tait
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#345

Post by Ali Tait »

Ok, I will, thanks Nick. Listening further with the new board it is indeed still distorting with full output from the Touch. :(
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