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discrete badger View Drop Down
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    Posted: 23 Apr 2012 at 7:55pm
Remote control of volume?

I am intrigued by some of the feedback on this thread and some I've read elsewhere. Some say that all decent DAC chips sound fairly similar and a key differentiator is the quality of the analogue stages after the chip. In that case a Slee DAC should have a lot to offer. On the other hand, some DACs in this price bracket do a lot of DSP tricks to clean up and reclock the input signal before it hits the DAC chip. With a very clean signal (e.g. coaxial SP/DIF from a top-flight transport capable of square waves with minimal jitter) these tricks are going to be less relevant than synchronous USB from a laptop.

On the bit width / sample rate question I recommend Dan Lavry's white papers, the first of which discusses sample rates. (www.lavryengineering.com - support). They've certainly opened my eyes to some of the myths of digital audio. His views don't sit well with the "bigger numbers = better" camp.  But, in the same way as for a Reflex or a Solo UL, when you listen to the result you quickly realise that the designer knows his stuff.
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ServerBaboon View Drop Down
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Originally posted by Graham Slee Graham Slee wrote:

 

Thank you for that feedback Steve. May I ask...

What type of DAC input for headphone amp? USB or S/PDIF or both?

For phono stage am I safe in assuming USB out? Or will there be a need for S/PDIF?

If USB for these items only, then please explain (somebody) why a particular bit/sample rate is required and what are the assumed benefits of one over another?

If anybody has in depth experience of USB, what do they reckon to the USB being handled by such as the Future Technologies FT230X USB to basic UART IC? (http://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT230X.pdf)

Personally I don't feel the need for SPDIF most digital  sources have analogue out except for computers, true some computers have spdif but not many. My thought for a HPA/DAC was a portable (with laptop) high quality music system.


Phono/ADC - USB out would mean compatibility with almost all computers, I have to admit on my attempts to record vinyl to to computer I have thought it to much of a faff and there are others on this forum who could comment more. Not sure about the support issues for this product either.


Bit depth/Frequency rate - Quite frankly the higher the numbers the better the quality (mmm see DB above), most audio (I think) is recorded at 24bit/192Khz (*) in the studio and some of the audiophile labels and hd tracks are releasing audio at 24 bit resolutions at various frequencies 48/96/192 (and others). a lot of the vinyl lathes also are operated by 24bit/192Khz sources with ADC in the head. A 24 bit 96Khz  recording will have a bandwidth of 30Kz, Checkout HiFi news in our local WH Smiths where they publish response charts for HD tracks in their music reviews.

I  know you have an aversion to the HiFi mags but if you want I can photocopy a writeup of an audio demo of a an audience listening to various levels of digital playback and their reaction.

Personally I listen to vinyl for pleasure but still enjoy other sources and I am considering a network streamer so she who should be obeyed can easily user her ipad to play the 600+ CDs on a server.


(*) Don't worry there are still a couple of analogue only studios left.



Edited by ServerBaboon - 23 Apr 2012 at 9:02pm
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ServerBaboon View Drop Down
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Originally posted by discrete badger discrete badger wrote:

Remote control of volume?

I am intrigued by some of the feedback on this thread and some I've read elsewhere. Some say that all decent DAC chips sound fairly similar and a key differentiator is the quality of the analogue stages after the chip. In that case a Slee DAC should have a lot to offer. On the other hand, some DACs in this price bracket do a lot of DSP tricks to clean up and reclock the input signal before it hits the DAC chip. With a very clean signal (e.g. coaxial SP/DIF from a top-flight transport capable of square waves with minimal jitter) these tricks are going to be less relevant than synchronous USB from a laptop.

On the bit width / sample rate question I recommend Dan Lavry's white papers, the first of which discusses sample rates. (www.lavryengineering.com - support). They've certainly opened my eyes to some of the myths of digital audio. His views don't sit well with the "bigger numbers = better" camp.  But, in the same way as for a Reflex or a Solo UL, when you listen to the result you quickly realise that the designer knows his stuff.

Yes the analogue stage is important but what I was trying to say due to the increasingly saturated market what would be the expected quantities of units to be sold, how would a Slee dac (relatively unknown)  be marketed against the dirt cheap far east dacs or the DCS, Audiolab, HRT, Arcams of this world who are known 'experts' in digital play back never mind the new high end names.


The Lavry document is interesting, did I understand that 96Khz is optimal, interestingly isn't SPDIF only specced to 96Khz?

This document is 8 years old will things not have improved since then?

But at the end of the day if I buy a 24 bit high frequency file from hd tracks, Linn, Naim or BW I want to be able to play them back at this frequency not have it go though some transcoding mangler.




Edited by ServerBaboon - 23 Apr 2012 at 9:05pm
Steve

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Various bits of GSP Kit ..well two so far, unless you count the cables that is.
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discrete badger View Drop Down
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Originally posted by ServerBaboon ServerBaboon wrote:

 
how would a Slee dac (relatively unknown)  be marketed against the dirt cheap far east dacs or the DCS, Audiolab, HRT, Arcams of this world who are known 'experts' in digital play back never mind the new high end names.

It would have to do for digital sources what the Reflex does for TTs and the Solo UL does for headphones. I do think people will give it a chance - audition it - just because of the reputation of those two units. 

Originally posted by ServerBaboon ServerBaboon wrote:

 

The Lavry document is interesting, did I understand that 96Khz is optimal, interestingly isn't SPDIF only specced to 96Khz?

This document is 8 years old will things not have improved since then?

No and I think that's part of his point. There are fundamental reasons why more is less. 
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Fatmangolf View Drop Down
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There are a number of us who are interested and discussing the tech specs. I am one of us, and wondered about the supply and demand - which makes me think Hives rather than price elasticity. Anyway what would we pay for a top notch DAC/ADC from Graham, and how many units are needed to make this viable?
 
Jon
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Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC.
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ServerBaboon View Drop Down
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Originally posted by discrete badger discrete badger wrote:

No and I think that's part of his point. There are fundamental reasons why more is less. 


Although it looks like Dan has been forced to play the numbers game as well since his dacs are 24/96 capable.




Edited by ServerBaboon - 23 Apr 2012 at 9:36pm
Steve

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discrete badger View Drop Down
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SP/DIF refers to the encoding method and is actually the same thing whether transmitted optically via fibre or electrically via coax. Some dislike optical because the LED in the transmitter takes too long to reach full brightness, thus giving the receiver a difficult job of deciding when the LED has reached the state of being on. The inverse for the process of the LED switching off. This is also the reason why it "tops out" at 96kHz. On the other hand, optical works well for long transmission distances and offers ground loop isolation.

In  my liviing room I have a 20m long fibre which runs from a coffee table holding a laptop or DAP to the back of my rack. I use an async USB to SPDIF converter to drive the fibre. The quality is excellent and I rarely play CDs from their physical media.
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