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Old 5th December 2005, 06:13 AM   #461
sanjeev is offline sanjeev  United States
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Default WTB Audiosector DAC

I would be interested in purchasing an assembled Peter Daniel DAC if anybody has one they don't need anymore.

Peter, please let me know if you think this post doesn't belong here.

Thanks!
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Old 5th December 2005, 06:22 AM   #462
Nordic is offline Nordic  South Africa
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In setting up the GC I finished yesterday, I accidentaly connected a speaker between the 2 positive output poles of the 2 channels...
And it played? is this bridgeing? or is this just how to connect a subwoofer...

I would never have intentionaly tried this...lol

Sorry Peter, I just thought if anyone knew what I experienced there for the first time, it would be you.
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Old 5th December 2005, 08:34 AM   #463
lohk is offline lohk  Europe
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You found the "pseudo surround trick" by chance - as so many others: You will hear only the signal difference between left and richt channel, no mono signals.
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Old 6th December 2005, 01:35 AM   #464
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Default Re: WTB Audiosector DAC

Quote:
Originally posted by sanjeev
I would be interested in purchasing an assembled Peter Daniel DAC if anybody has one they don't need anymore.

Peter, please let me know if you think this post doesn't belong here.
I don't mind posts like that at all. I also like buying second hand to save
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Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it. - JC
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Old 6th December 2005, 09:18 AM   #465
Magsy is offline Magsy  United Kingdom
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Just finished my 3875 premium and after a false start I have it working fine, it sounds far better than I had expected

One slight issue is that with my 91dbm speakers there is some hiss, I can be heard within a few feet of the speakers and over the music and very low volumes. It does not increase with volume.
It happens with preamp connected or not, its an always present type hiss. It is much less with 87dbm speakers.

DC offset is very low, sub 40mv at least (can't remember off top of my head) The amp(s) are cased, wiring is short and twisted.

At present nothing is grounded bar the chasis,all components/jacks are isolated.

Is there anything I can do to fix this? Is it to do with me not hooking up ground?

I've also read about leaving R1 out, I assume I jumper this position? Is it worth doing?
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Old 6th December 2005, 10:09 AM   #466
lohk is offline lohk  Europe
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Does it hiss with inputs shortened? Than it is probably oscillating at high frequencies. All my Chipamps show only very little hiss, audible only with most of the speakers with my ears quite close to the tweeter.
I also would never leave out R1, in my experience this is an important part for stabilty, although i did not really find an evidence for that in the spec sheet. My Chipamps always seem to work better with R1 in place (but 150-220R not 1k).
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Old 6th December 2005, 11:57 AM   #467
Colin is offline Colin  United Kingdom
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Quote:
Originally posted by Peter Daniel
This time for sure, I remember you needed one.
Thanks, Peter. I promise this time that there will be no typographical comments!

Colin
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Old 6th December 2005, 04:26 PM   #468
Magsy is offline Magsy  United Kingdom
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Quote:
Originally posted by lohk
Does it hiss with inputs shortened? Than it is probably oscillating at high frequencies. All my Chipamps show only very little hiss, audible only with most of the speakers with my ears quite close to the tweeter.
I also would never leave out R1, in my experience this is an important part for stabilty, although i did not really find an evidence for that in the spec sheet. My Chipamps always seem to work better with R1 in place (but 150-220R not 1k).
Just testing it out now. With shorted inputs the hiss is tiny, well within acceptable limits.

As soon as I connect the preamp there is much more hiss.

With nothing connected there is hiss and hum, but I'm led to believe this is to be expected.

Groudning seems to make no difference to hiss.

So it looks like my preamp, which is a M headphone amplifier, is the cause. ( http://www.amb.org/audio/mmm/ )

Too much gain? The GC is a default of 33 and the headamp is 10, the volume does come up pretty quick, with max being about 10-11oclock.

I have 23mv / 14mv of DC offset on the GC with music playing and speakers connected (pretty much any volume)

I get no hiss on the headamp with my HD580s...nor when the speakers are directly connected to the headamp (it produces ~6 watts)

I have a simpler OPA637/BUF634 headamp I will try later as a preamp (Pimeta)
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Old 6th December 2005, 04:42 PM   #469
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Yes, the hiss is from your preamp. If I fully open volume on my ML380S I also get some hiss.

You can reduce the gain of the amp. One way would be replacing 680R resistor with 1k2 resistor (or similar).

When no input connected to the amp, the noise and hum are normal, the input has to be loaded for proper operation.

You can try to short the input 220R resistor (I'm doing it presently with my amps). The advantage would be less coloration that this resistor inevitably introduces.
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Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it. - JC
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Old 6th December 2005, 07:14 PM   #470
karma is offline karma  Canada
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peter do you have any of the classic lm3875 in stock?

pic of my dac geting some wood
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