Integrated gainclone, NOSDAC and DAR

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#21
Excellent ... thanks fior the clarification. Keep up the good work.

! & 2: I as well have no problems with the EtherNet connections, wireless or otherwise. I guess I was just trying to discover your motives if other than convenience = no wires. (I have not seen any effect of the wired connection visa vis power supply noise feed through, etc.)

3: " ... I personally feel you are better off choosing your own DAC and using the SPDIF out on the SB3. I have been extremely happy using an outboard DAC; first a modded Bel Canto and now Peter's NOSDAC. ..." ... good advise.

Thanks for taking the time to answer my pecular questions.
 
#27
Kooka,
The squeezebox does come with it's own onboard DAC. As a stock unit i found it quite flat so have always used an outboard DAC. First a Bel Canto and now Peter's NOSDAC. With an outboard DAC the I found that the sound improved tremendously. If you search the forums you will find that others have had similar experiences and opted for another DAC.
In the next week or so i plan on implementing a buffer circuit, at which point i feel that i will be in a better position to comment on the sound of the whole get up
 
#29
added buffer

I finally added Peter's buffer. The sound has improved remarkebly and the amp seems to have an easier time driving my speakers.
I can only describe the sound as being easier and more control over the base.
I didn't swap out the coupling caps on the DAC, and once eveything was wired up i hadn't left any room to desolder... oh well next time.
I am very happy with the way it all worked out. It is dense inside the chassis, what with 4 toroids, one smps and 6 boards.
 
#36
Neil,

First of all, great job! I'm sure many others thought about a solution like yours, but you executed it! Wow! I looked at those enclosures you used but they looked a little pricey for me!

Anyway...I was curious with regards to the buffer you added. I'm trying to figure out why you needed the buffer, or the extra 'oomph.' The output voltage of Peter Daniels' NOS dac I believe is about 2V, so it has plenty as the input sensitivity of these gainclones are about 0.6V RMS. Most of my colleagues have told me that even if you match up the DAC and amplifier perfectly, you still ought to have about 8-12 dB of headroom. So that looks like the answer here.

:smash:I'm currently finishing up my gainclone amp using Peter's boards. Per his recommendation I'm also using a pair of Plitron 400VA transformers. In addition, I've added a pair of Lundahl input transformers for 6dB stepdown switching. I'm also finishing up Peter's NOS dac + HagUSB in one enclosure. I have a transformer coupled tube preamp using Magnequest transformers that should sound pretty good here.

All very, very cool and inspiring.

Thanks for the bandwidth,

Anand.
 
#37
Anand,
My transformers may have been slightly undersized (a pair of 120VAC) which in my ear / mind appeared to truncate some of the sound.
It was purely on a whim that i decided to add the buffer. I think it made a difference, subtle but definitely there.
I had made no allowance for a pre-amp and i believe the buffer fills that role.
Regardless, it sounds like your setup is going to be pretty ideal. I would be interested to hear what you think of the tube pre with the gainclone.

Thanks for the words.
Neil
 
#38
nycavsr2000 said:
Anyway...I was curious with regards to the buffer you added. I'm trying to figure out why you needed the buffer, or the extra 'oomph.' The output voltage of Peter Daniels' NOS dac I believe is about 2V, so it has plenty as the input sensitivity of these gainclones are about 0.6V RMS. Most of my colleagues have told me that even if you match up the DAC and amplifier perfectly, you still ought to have about 8-12 dB of headroom. So that looks like the answer here.
Click to expand...

The buffer does not add any gain. It is a stage that provides impedance matching. The output of the DAC is based on passive I/V and as such its output impedance is rather high at 2k7 ohm. Adding a buffer directly after the DAC, lowers the output impedance of that stage to 6ohm, which translates in better impedance match to the next stage and is expressed in more dynamic and dimentional sound.
 
#39
Peter,

Thanks for the explanataion. I overlooked/didn't know what the output impedance of your NOS dac which you say is 2700 ohms. So indeed you would want an amp/preamp whose input impedance is at least 10 times or about 30K to prevent high frequency rolloff and limited dynamics. I was about to ask you what the output impedance of your dac was, but you beat me to it!

Thanks,
Anand.
 
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