Google Search  |  Meridian Systems  |  Meridian Streaming  |  Restaurant  |  WiKi  |  Duncan's Meridian Info  |  Board Rules  |  Restaurant Rules
Page 1 of 2 1 2 >
Topic Options
Rate This Topic
#91419 - 2009-04-13 23:45 Stereophile Review of Meridian 808.2
Registered: 2000-05-30
Posts: 2,641
Frank Offline
Great Green Arkleseizure
Frank Offline
Great Green Arkleseizure

Registered: 2000-05-30
Posts: 2,641
Loc: Nashville, Tennessee, USA
Stereophiles review of the 808.2 is now up at their website:

http://www.stereophile.com/cdplayers/mer...fier/index.html


Two-channel: Meridian G02, G08, 557, Director, Explorer, Prime
Multi-channel: Meridian G68ADV, HD621, DSP5500s, DSP5000C

Founder and Editor
Ultra High-End Audio and Home Theater Review
www.ultrahighendreview.com
Top
#91424 - 2009-04-14 02:14 Re: Stereophile Review of Meridian 808.2 [Re: Frank]
Registered: 2000-05-28
Posts: 8,672
Fiddler Offline
President of the Imperial Galactic Government
Fiddler Offline
President of the Imperial Galactic Government

Registered: 2000-05-28
Posts: 8,672
Loc: Northeastern, USA
Great review. Didn't have time to read the whole thing in detail.

But one thing that immediately caught my eye was the at length discussion of apodizing filter and how it helps restore problems from ORIGINAL A/D conversion.

So why is it that in the current context of discussion to date that the apodzing fileter is only applied if Meridian applies upsampling?

Am I missing something, did John Atkinson miss something (doubtful I know)?


- Fiddler (IMHO)

If you think listening to music is fun, try learning an instrument.
HT: G61RSL, 4x5K, 5.5KHC, 2xSC6000, Transporter, HD621, Philips BDP7501 4K, Tivo, 65" LG OLED 4K C6
Computer: Foobar2000, 5K, Mojo, HiFiMan HE1000 V2
Top
#91426 - 2009-04-14 03:19 Re: Stereophile Review of Meridian 808.2 [Re: Fiddler]
Registered: 2001-11-05
Posts: 703
DLinsley Offline
Formerly Meridian506 Paranoid android
DLinsley Offline
Formerly Meridian506
Paranoid android

Registered: 2001-11-05
Posts: 703
Loc: Seattle, USA
I was going to post about the following last week after reading the print issue, but forgot. However:

Originally Posted By: Stereophile Review
The apodizing filter used in the 808.2 and 808i.2 was optimized using listening tests. It is realized using a DSP chip operating at 150MIPs with 48-bit precision that also performs the upsampling. It appears that the CD data are first upsampled to 88.2kHz, then processed by the apodizing filter which has a null at 22.05kHz.


So hopefully the G68 (and G61R to relate to the other thread) will be a candidate for upgrade. At only 6 channels in currently, that would be just 450 of the 900MIPS available - hopefully the remaining 450MIPS is good enough for MRC and 6->8 channel expansion.


Theater: G68ADV, Anthem MRX-1120, DSP5500.3 x 3, M33x4, Kef Ci200QRx4 Rythmik D15 sub, JVC RS600, RadiancePro, Panamorph UH480, Oppo 103 + Vanity 103 Lite
Living room: DSP5000.3
Kitchen: F80
Bathroom: P200ZQ
Work: Explorer
Top
#91428 - 2009-04-14 03:53 Re: Stereophile Review of Meridian 808.2 [Re: DLinsley]
Registered: 2000-05-28
Posts: 8,672
Fiddler Offline
President of the Imperial Galactic Government
Fiddler Offline
President of the Imperial Galactic Government

Registered: 2000-05-28
Posts: 8,672
Loc: Northeastern, USA
I think I'd give up a bunch of MRC filters for it. I think I typically use about half.


- Fiddler (IMHO)

If you think listening to music is fun, try learning an instrument.
HT: G61RSL, 4x5K, 5.5KHC, 2xSC6000, Transporter, HD621, Philips BDP7501 4K, Tivo, 65" LG OLED 4K C6
Computer: Foobar2000, 5K, Mojo, HiFiMan HE1000 V2
Top
#91431 - 2009-04-14 05:46 Re: Stereophile Review of Meridian 808.2 [Re: DLinsley]
Registered: 2004-04-15
Posts: 12,640
VirusKiller Offline
Don't Panic
VirusKiller Offline
Don't Panic

Registered: 2004-04-15
Posts: 12,640
Loc: nr. Milton Keynes, UK
Originally Posted By: meridian506
At only 6 channels in currently, that would be just 450 of the 900MIPS available - hopefully the remaining 450MIPS is good enough for MRC and 6->8 channel expansion.
Unfortunately, it doesn't quite work like that. Until the G68 "morphed" into a 900 MIPS machine from 750 MIPS, it was believed that 150 MIPS was available for upsampling on the receiver card with the other 600 MIPS reserved for DSP presets, time and level alignment, and MRC. So is the split now 300 MIPS and 600 MIPS? Not clear at all. Also, whilst the 808.2 uses a 150 MIPS chip, I doubt that all of it is used up.


Roon Developer and ex-moderator of this Forum
I am #25 in the HH1 photo of fame.
Top
#91433 - 2009-04-14 07:52 Re: Stereophile Review of Meridian 808.2 [Re: VirusKiller]
Registered: 2004-07-21
Posts: 1,792
MI' Offline
Knows where his towel is
MI' Offline
Knows where his towel is

Registered: 2004-07-21
Posts: 1,792
Loc: United Kingdom
Dear All,

Stereophiles review of the 808.2 is now up at their website:

It has been on Duncan's site for some time too.

Regards


Under review
Top
#91435 - 2009-04-14 08:38 Re: Stereophile Review of Meridian 808.2 [Re: MI']
Registered: 2004-04-15
Posts: 12,640
VirusKiller Offline
Don't Panic
VirusKiller Offline
Don't Panic

Registered: 2004-04-15
Posts: 12,640
Loc: nr. Milton Keynes, UK
Interesting review (now that I've actually read it). Lots of brownie points to the team from Huntingdon...

Regarding the 150 MIPS chip, I noted that it is used to upsample (and apodize) to 88.2kHz for the digital outputs, and is also required to upsample the 88.2kHz (conventionally) to 176.4kHz for the internal DACs. These would seem to be separate operations (I can't see how they could be combined), so apodizing a stereo signal will require considerably less than 150 MIPS.


Roon Developer and ex-moderator of this Forum
I am #25 in the HH1 photo of fame.
Top
#91471 - 2009-04-14 15:22 Re: Stereophile Review of Meridian 808.2 [Re: Fiddler]
Registered: 2003-09-04
Posts: 137
ScottB Offline
Hitchhiker
ScottB Offline
Hitchhiker

Registered: 2003-09-04
Posts: 137
Loc: Lake Oswego, Oregon, USA
Originally Posted By: George Mills
Great review. Didn't have time to read the whole thing in detail.

But one thing that immediately caught my eye was the at length discussion of apodizing filter and how it helps restore problems from ORIGINAL A/D conversion.

So why is it that in the current context of discussion to date that the apodzing fileter is only applied if Meridian applies upsampling?

Am I missing something, did John Atkinson miss something (doubtful I know)?


The discussion of eliminating artifacts from the original A/D conversion is not a function of apodising filters per se, but rather a function of the specific filter parameters chosen. Peter Craven, when he originally proposed minimum phase filters, also proposed that the filter should roll off very steeply after 20 khz, more steeply even than the usual filters applied at the A/D and D/A conversion. That way, any ringing from the A/D conversion process would be filtered out, albeit at the expense of considerable post-ringing and phase shift from the apodising filter itself - which shows up in JA's measurements.

By contrast, the Ayre white paper I've mentioned frequently before claims that their implementation sounds better with quite gentle filter slopes, which will obviously allow more ringing from A/D conversion to get through, as well as more aliasing distortion, but will create much less post-ringing from the minimum phase filter. That's a pretty interesting disagreement between the ears of two of the best digital audio designers in the business, and JA's evaluation of the new Ayre MP filter will bear watching.

BTW, you must upsample to do apodising, or any digital anti-aliasing filtering, because the filter knee is so close to the Nyquist frequency. Whether you speak of the filtering being applied after upsampling, or as part of the upsampling process, is really a matter of semantics. From the perspective of upsampling the original digital signal, you must upsample in order to filter, and you must filter if you upsample.




861v?, MBL 116/111/121, McIntosh amps, music server, Oppo/switch-box 980 SACD/DVD
Top
#91475 - 2009-04-14 15:39 Re: Stereophile Review of Meridian 808.2 [Re: ScottB]
Registered: 2004-04-15
Posts: 12,640
VirusKiller Offline
Don't Panic
VirusKiller Offline
Don't Panic

Registered: 2004-04-15
Posts: 12,640
Loc: nr. Milton Keynes, UK
Hmm. I seem to recall Bob Stuart mentioning "more gentle" rolloffs. I guess this is why the choice of algorithm came down to listening tests in the end; human psychoacoustics is simply too complex and too poorly understood to do more than generate technical "options" for aural evaluation.


Roon Developer and ex-moderator of this Forum
I am #25 in the HH1 photo of fame.
Top
#91479 - 2009-04-14 15:58 Re: Stereophile Review of Meridian 808.2 [Re: VirusKiller]
Registered: 2003-09-04
Posts: 137
ScottB Offline
Hitchhiker
ScottB Offline
Hitchhiker

Registered: 2003-09-04
Posts: 137
Loc: Lake Oswego, Oregon, USA
Originally Posted By: VirusKiller
I guess this is why the choice of algorithm came down to listening tests in the end; human psychoacoustics is simply too complex and too poorly understood to do more than generate technical "options" for aural evaluation.


If you've ever listened to that interview/lecture Stuart did for the UK AES, that's almost word for word what he said. Thankfully, there are engineers like Stuart who are willing to trust their ears over their instruments.




861v?, MBL 116/111/121, McIntosh amps, music server, Oppo/switch-box 980 SACD/DVD
Top
#91482 - 2009-04-14 16:09 Re: Stereophile Review of Meridian 808.2 [Re: ScottB]
Registered: 2004-08-07
Posts: 7,868
Ian Offline
President of the Imperial Galactic Government
Ian Offline
President of the Imperial Galactic Government

Registered: 2004-08-07
Posts: 7,868
Loc: Surrey, England, UK
VK. Were you awake at the time ? wink


Meridian owner since 1992
Prime & PSU, Focal Elear headphones, Roon (ROCK 8Gi5 Nuc), Explorer 1 & 2, F80. 200/203, various Sonos (via Roon).
Top
#91486 - 2009-04-14 16:42 Re: Stereophile Review of Meridian 808.2 [Re: Ian]
Registered: 2004-04-15
Posts: 12,640
VirusKiller Offline
Don't Panic
VirusKiller Offline
Don't Panic

Registered: 2004-04-15
Posts: 12,640
Loc: nr. Milton Keynes, UK
Originally Posted By: Ian
VK. Were you awake at the time ? wink
Must have been if my recollection was spot on! wink

@scott: I was at the lecture!


Roon Developer and ex-moderator of this Forum
I am #25 in the HH1 photo of fame.
Top
Page 1 of 2 1 2 >

Moderator:  Carl, Duncs, ncpl 
Who's Online
1 registered (Not'arf), 72 Guests and 1 Spider online.
Key: Admin, Global Mod, Mod
Newest Members
Ehsaanul_Haq, Xebxorro, LeonardoDelgado, SunValleyLaw, PaulMichaelMiller
4821 Registered Users
Top Posters (30 Days)
Mike_500 39
Ratbert 33
3dit0r 27
CMB Integrations - Bruce 22
Jeremy A-H 21
Top Posters
VirusKiller 12640
Fiddler 8672
ncpl 8578
Carl 8007
Ian 7868
Forum Stats
4,821 Registered Members
18 Forums
26,898 Topics
268,893 Posts

Most users ever online: 607 @ 2020-01-20 17:19
Meridian  |  Media Centre  |  Support  |  Firmware Release Notes  |  RSS Systems  |  RSS Streaming  |  RSS Restaurant