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  »  New  Recording options: Pacific Microsonics vs. Lavry Gold...  Pacific Microsonics vs. Lavry Gold in D/A mode....  Didital Things  Forum     24  218682  09-27-2007
  »  New  The BSO and Digital Music...  Around the BSO recording practice....  Didital Things  Forum     44  265307  12-02-2008
  »  New  DA architecture: True Multibit vs. anything else...  If it might…....  Didital Things  Forum     17  144663  12-09-2007
  »  New  The optimum Sampling Rate for bass...  Lynx can handle up to 200.000Khz...  Didital Things  Forum     3  32820  02-19-2008
  »  New  Analog Transfer: the first draft...  What I am after in this test....  Didital Things  Forum     19  126784  04-11-2006
  »  New  Weiss Engineering DAC202..  Attenuation...  Didital Things  Forum     5  40221  06-21-2010
  »  New  Pacific Microsonics Model Two: What Platform, Software ..  XLR to RCA adaptor. Watch out...  Didital Things  Forum     1  21277  03-17-2011
  »  New  Berkeley Audio Design's Alfa Reference DAC...  Well, it fits the pattern....  Didital Things  Forum     4  32077  09-02-2014
05-27-2010 Post does not mapped to Knowledge Tree
manisandher
London
Posts 157
Joined on 09-05-2008

Post #: 81
Post ID: 13626
Reply to: 13380
Some interesting information
fiogf49gjkf0d
I asked Dave Peck of Avid (formerly Euphonix) a few questions regarding the Model Two (otherwise known as the PMI). The responses he received from Keith Johnson (one of the original designers of the PMI, head of Reference Recordings and chief design engineer at Spectral Audio) are shown below:
 
1. What is the max. RMS output voltage of the Model Two? 
The PMI converters produce a specified maximum output of +24 dBu from 0 dB FS modulation, which translates to 12.28 volts RMS. or 34.7 Volts peak to peak as seen on a scope. I believe the output impedance is less than 20 ohms so the machines produce roughly 11.5 Volts into a 600 ohm load. The driving amplifier is capable of at least twice this output so it can accommodate DAC outputs with ringing and other filter artifacts that might be introduced or chosen for sonic reasons. It can energize loudspeakers to reasonable volume.

2. Having used the Model Two for a year or so now, I am convinced that it is non-oversampling at 176.4/192KHz rates. Could you confirm this either way?
Up conversion is not used at 176.4 kHz and 192 kHz sample rates. Instead, A passive analog filter with group delay correction removes alias products so that all 24 bits of information are captured from each sample by the ADC process. Conversion is made with ladder-pipeline architectures and analog added - DSP subtracted dithering, a first of its kind that is still used for instrumentation. Unlike sigma-delta methods, jitter sensitivity is low and accuracy does not degrade at high program levels.
 
Mani.
05-27-2010 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,734
Joined on 05-28-2004

Post #: 82
Post ID: 13627
Reply to: 13626
The Keith Johnson’s response.
fiogf49gjkf0d

 manisandher wrote:
I asked Dave Peck of Avid (formerly Euphonix) a few questions regarding the Model Two (otherwise known as the PMI). The responses he received from Keith Johnson (one of the original designers of the PMI, head of Reference Recordings and chief design engineer at Spectral Audio) are shown below:
 
1. What is the max. RMS output voltage of the Model Two?
The PMI converters produce a specified maximum output of +24 dBu from 0 dB FS modulation, which translates to 12.28 volts RMS. or 34.7 Volts peak to peak as seen on a scope. I believe the output impedance is less than 20 ohms so the machines produce roughly 11.5 Volts into a 600 ohm load. The driving amplifier is capable of at least twice this output so it can accommodate DAC outputs with ringing and other filter artifacts that might be introduced or chosen for sonic reasons. It can energize loudspeakers to reasonable volume.

2. Having used the Model Two for a year or so now, I am convinced that it is non-oversampling at 176.4/192KHz rates. Could you confirm this either way?
Up conversion is not used at 176.4 kHz and 192 kHz sample rates. Instead, A passive analog filter with group delay correction removes alias products so that all 24 bits of information are captured from each sample by the ADC process. Conversion is made with ladder-pipeline architectures and analog added - DSP subtracted dithering, a first of its kind that is still used for instrumentation. Unlike sigma-delta methods, jitter sensitivity is low and accuracy does not degrade at high program levels.

Mani, I am not sure what Mr. Johnson meant by saying that Pacific’s output “can energize loudspeakers to reasonable volume”. It sound ridicules statement coming from him. Anyhow, about the second question. Since it uses ladder-resistor architecture then it is multibit, which is good. Multibit at 4x sampling rate would require much less alias removed, if any. This is what I would like to try – to run 4X DAC with no post-conversion filter of any kind – with multibit architecture it is possible in case my electronics can handle HF. Do not forget the I power my system with Melquiadeses that have low pass filters built-in (bias resistor in grid against the Miller capacitance of the driver tube).

The Pacific’s however do not have the output as a normal multibit. If you look at the Pacific’s output at minus 90-100dB then you will not see the individual sticks as it would be with other pure Multibits (Lavry 924). The individual sticks will be blurred and I think that here is where the Pacific’s dithering in work.

I understand that you like the sound of your Pacific but you do not know it sound as you use just D/A section. The Pacific A/D section is much more interesting then it’s D/A section. You need to record with Pacific to get a true understanding what kind machine it is. In addition as I understand Pacific has an ability to write dither during recording and then to inject in D/A the same dither in the opposite polarity – this is superbly cool idea. Anyhow, start to record and you will love this processor even more.

Rgs, Romy the Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
05-27-2010 Post does not mapped to Knowledge Tree
manisandher
London
Posts 157
Joined on 09-05-2008

Post #: 83
Post ID: 13628
Reply to: 13627
What to record?
fiogf49gjkf0d
 Romy the Cat wrote:
Anyhow, start to record and you will love this processor even more.

I'd love to give this a go... I just need something worth recording!

I have a good FM antenna on my roof and a half-decent tuner in the guise of a Rotel RHT-10, but I don't think the FM in the UK is up to much - it's all NICAM stereo - though I do like a lot of what BBC Radio 3 puts out live.

My turntable? Well, a Technics SP-10 on a wall-mounted solid metal plinth with 3009 S2 (pre-improved) and a trusty old 103 - perfect for playing the badly-scratched LPs of my student days, but perhaps not up to much else.

Another option is to buy an open-reel machine. But I suspect that sourcing interesting material would be difficult.

The final option is recording live. And this is the one I'll probably pursue. My own musical skills are totally dire, but I know a few amateur musicians who I might be able to start off with.

If I go for the last one, do you (or anyone else) have any ideas on good value-for-money mics and pres that I could plug straight into the Model Two?

Mani.
06-01-2010 Post does not mapped to Knowledge Tree
manisandher
London
Posts 157
Joined on 09-05-2008

Post #: 84
Post ID: 13674
Reply to: 13628
Really putting the horse before the cart
fiogf49gjkf0d
EDIT: I was obviously so distressed about what I was just about to write that I got the title of this thread totally wrong. Of course, it should read, "Really putting the cart before the horse".

It's dawned on me that it's a bit silly to buy a recorder and then look around for something to record... for the sake of recording something. I'm usually more rational than this.

The Model Two is a great DAC. If its ADC is even better, then it must be something truly special. And unfortunately, something that I will never be able to take full advantage of.

I think I will be putting my unit up for sale. I've already been approached by a mastering engineer in Australia. Hopefully, I'll find a good home for it...

Mani.
06-21-2010 Post does not mapped to Knowledge Tree
manisandher
London
Posts 157
Joined on 09-05-2008

Post #: 85
Post ID: 13804
Reply to: 13674
What was I thinking?
fiogf49gjkf0d
Following on from my last two posts, I finally managed to try the Model Two in AD mode. With the Model Two set to 24/4fs and wordclock master, I cannot discern a difference between the source and the source passing through the Model Twos AD/DA. Furthermore, and much to my delight, I cannot discern a difference between the source and the source passing through AD/AES/PC/AES/DA. It's good to know that my RME AES-32 and my 'cheap' Sommer AES cables provide a transparent connection between the PC and the Model Two.

Another nice surprise is that some 16/44.1 files I've recorded from a one-sided 45rpm LPs sound so much better than the CD rips of the same albums. The digitized vinyl files have 'life' - the CD rips sounds 'cold' and 'dead' in comparison. I know that Romy has written extensively about the issue with CD rips, but it amazes me that there can be such a difference, even with a modest vinyl setup such as mine.

In any event, the up-shot of all this is that I will certainly NOT be putting the Model Two up for sale. Instead, I will begin getting hold of as much interesting vinyl as I can, digitizing it and listening to these files. I suspect that this will become my main source of music until more good-sounding downloads become available.

But I have one issue. Using RME's Digicheck software, I can see a fair amount of energy coming off the vinyl right up to ~40KHz (and a gradual decline thereafter). But I'm seeing some periodically varying 'noise' of up to -20dB (!) at ~25Hz. I'm not sure what's causing this. It certainly isn't feedback from the speakers - I do all my recording with the volume set to zero.

Perhaps this is off-topic, but it would be good if someone could just verify if this is resonance caused by using a low compliance cartridge with a 3009 pre-improved. If so, could I improve things by changing to a new plinth and switching to a 3012 (or perhaps a new M2 12-R)? Should I do away with the 103 altogether and get a new cartridge/arm, considering that I want to make high-quality recordings?

Any thoughts much appreciated.

Mani.
06-22-2010 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,734
Joined on 05-28-2004

Post #: 86
Post ID: 13811
Reply to: 13804
This is very typical.
fiogf49gjkf0d
 manisandher wrote:
Another nice surprise is that some 16/44.1 files I've recorded from a one-sided 45rpm LPs sound so much better than the CD rips of the same albums. The digitized vinyl files have 'life' - the CD rips sounds 'cold' and 'dead' in comparison. I know that Romy has written extensively about the issue with CD rips, but it amazes me that there can be such a difference, even with a modest vinyl setup such as mine.

 This is very-very common. You do not need spend a lot of efforts to get better sound than commercial transfers. The commercial transfers are mostly over mastered as have a lot of DSP manipulation, not to mention the rates and resolution conversions. Do not also forget that with commercial transfers you are listening CD, not the raw files. Try to render your raw file to CD format and you will lose 60% of Sound…


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
Page 5 of 5 (86 items) Select Pages:  « 1 2 3 4 5
   Target    Threads for related reading   Most recent post in related threads   Forum  Replies   Views   Started 
  »  New  Recording options: Pacific Microsonics vs. Lavry Gold...  Pacific Microsonics vs. Lavry Gold in D/A mode....  Didital Things  Forum     24  218682  09-27-2007
  »  New  The BSO and Digital Music...  Around the BSO recording practice....  Didital Things  Forum     44  265307  12-02-2008
  »  New  DA architecture: True Multibit vs. anything else...  If it might…....  Didital Things  Forum     17  144663  12-09-2007
  »  New  The optimum Sampling Rate for bass...  Lynx can handle up to 200.000Khz...  Didital Things  Forum     3  32820  02-19-2008
  »  New  Analog Transfer: the first draft...  What I am after in this test....  Didital Things  Forum     19  126784  04-11-2006
  »  New  Weiss Engineering DAC202..  Attenuation...  Didital Things  Forum     5  40221  06-21-2010
  »  New  Pacific Microsonics Model Two: What Platform, Software ..  XLR to RCA adaptor. Watch out...  Didital Things  Forum     1  21277  03-17-2011
  »  New  Berkeley Audio Design's Alfa Reference DAC...  Well, it fits the pattern....  Didital Things  Forum     4  32077  09-02-2014
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