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HEDD192 L+R=????
Old 23rd March 2003
  #1
Gear Guru
 
thethrillfactor's Avatar
 
4 Reviews written
🎧 15 years
HEDD192 L+R=????

Has anyone noticed on the HEDD 192, when using both the D/A and A/D (synchroniously) that the L+R A/D are 1 sample off from each other?

I've been having phase issues with the HEDD and did a Spectrafoo Phase Torch test and discovered this anomaly. It creates some combfiltering in the highs.

I am shipping my HEDD 192 out to Dave this week, but i was just wondering if anyone with this unit has exhibited the same issues.

Peace.
Old 23rd March 2003
  #2
Founder
 
Jules's Avatar
One sample?



Oh dear!



heh

Old 23rd March 2003
  #3
member no 666
 
Fletcher's Avatar
 
🎧 15 years
Yeah... that's the latency of the processing... 1 sample. Pretty damn good ain't it!!
Old 23rd March 2003
  #4
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thethrillfactor's Avatar
 
4 Reviews written
🎧 15 years
Quote:
Originally posted by Fletcher
Yeah... that's the latency of the processing... 1 sample. Pretty damn good ain't it!!
Fletcher,

The funny part is that it doesn't happen when the processing is engaged digitally only when doing a L+R A/D conversion.
Old 23rd March 2003
  #5
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thethrillfactor's Avatar
 
4 Reviews written
🎧 15 years
Quote:
Originally posted by Jules
One sample?



Oh dear!



heh

Hey if one sample will cause comb filtering...than yeah...

dfegadONE SAMPLE!!!!

Old 23rd March 2003
  #6
Founder
 
Jules's Avatar
Keep us posted,

Interesting report,

Thank you.
Old 24th March 2003
  #7
member no 666
 
Fletcher's Avatar
 
🎧 15 years
Quote:
Originally posted by thethrillfactor
The funny part is that it doesn't happen when the processing is engaged
I'd recommend you double check that... when going 'Dig in-processor-Dig out' you're going to find "1 sample latency" from the processor.

Physics.
Old 26th March 2003
  #8
Gear Addict
 
🎧 15 years
i wish large format digital consoles had only a sample of latency.
Old 26th March 2003
  #9
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RKrizman's Avatar
 
🎧 15 years
Just to clarify, are you saying that there is a 1 sample difference between the left and right channels? Or a 1 sample throughput delay, the same for both left and right.

-R
Old 26th March 2003
  #10
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Etnier's Avatar
 
🎧 15 years
...well ThriillFactor says "when using both the D/A and A/D (synchroniously) that the L+R A/D are 1 sample off from each other".

I think Fletcher, however is referring to a more normal latency.

I do the sort of thing Thrill is talking about every day: out of my digital mixer at 48kHz to the HEDD AES input, out of the HEDD analog to mix processing, and back in to the HEDD A/D at 44.1. So, this is of some concern to me.

Anyone know what the cancellation effects of a one sample difference at 44.1 are?
Old 27th March 2003
  #11
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mwagener's Avatar
 
🎧 15 years
Quote:
Originally posted by Etnier
...Anyone know what the cancellation effects of a one sample difference at 44.1 are?
If I'm not mistaken the frequency effected by a 1 sample difference at 44,100 Hz should be 735.29 Hz.
Old 27th March 2003
  #12
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Etnier's Avatar
 
🎧 15 years
I always hated that freq anyhow...
Old 27th March 2003
  #13
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thethrillfactor's Avatar
 
4 Reviews written
🎧 15 years
Quote:
Originally posted by RKrizman
Just to clarify, are you saying that there is a 1 sample difference between the left and right channels? Or a 1 sample throughput delay, the same for both left and right.

-R
1 sample between left and right channel on the A/D.
Old 27th March 2003
  #14
Gear Maniac
 
🎧 15 years
Hi folks,

A sample delay between L & R is worser than a single frequency cancellation @ 44100hz.

On the mono information, you've got major HF attenuation starting @10Khz -3dB. The curve is quite exponential.
The 20Khz is totally cancelled !!!

You can notice this artifacts even is stereo.

The stereo image is shiffted by about 3Β° or 4Β° of center too.


Nice isn't it ? :-)

Salvator
Old 27th March 2003
  #15
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DigitMus's Avatar
 
🎧 15 years
You know, I've seen the same thing posted about several pieces of gear, and it's got me thinking. I wonder if this isn't a display problem with interleaved stereo digital formats, which (while in the digital domain) would inherantly be offset by one sample between the L & R because they use a serial bitstream. Presumably, they would be re-aligned during the D to A process - and during digital processing, should be extracted to separate, parallel streams for processing. I can't believe Dave Hill would let anything out with a severe problem as is being implied here, nor that his many top tier customers wouldn't have heard such a steep roll off above 10K.

Scott
Old 27th March 2003
  #16
Gear Addict
 
Etnier's Avatar
 
🎧 15 years
Anyone remember the PCM-F1, and the correction algorithm that's in the Lex 300?
Old 27th March 2003
  #17
Gear Guru
 
thethrillfactor's Avatar
 
4 Reviews written
🎧 15 years
Quote:
Originally posted by DigitMus
You know, I've seen the same thing posted about several pieces of gear, and it's got me thinking. I wonder if this isn't a display problem with interleaved stereo digital formats, which (while in the digital domain) would inherantly be offset by one sample between the L & R because they use a serial bitstream. Presumably, they would be re-aligned during the D to A process - and during digital processing, should be extracted to separate, parallel streams for processing. I can't believe Dave Hill would let anything out with a severe problem as is being implied here, nor that his many top tier customers wouldn't have heard such a steep roll off above 10K.

Scott

Again I am not posting to rag on Dave Hill's stuff(whiich is mostly great).

It may just be my Hedd 192 needs a look see(i do take it everywhere and maybe something happened while I was transporting it).

I was just curious if anyone had a similar problem with their units.
Old 27th March 2003
  #18
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RKrizman's Avatar
 
🎧 15 years
Quote:
Originally posted by thethrillfactor
1 sample between left and right channel on the A/D.
You must be joking. That is totally unacceptable. Mackie got spanked roundly for this when their D8B did the same thing. If it's true I'm sure it's something Dave Hill would want to know about in order to correct.

OTOH, who's to say that a 1 sample offset to one channel wouldn't excite the mix in a mysterious and possibly desireable way.

-R
Old 27th March 2003
  #19
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RKrizman's Avatar
 
🎧 15 years
Quote:
Originally posted by DigitMus
You know, I've seen the same thing posted about several pieces of gear, and it's got me thinking. I wonder if this isn't a display problem with interleaved stereo digital formats, which (while in the digital domain) would inherantly be offset by one sample between the L & R because they use a serial bitstream.
Scott
I doubt it. Whenever I do a bounce to disc (to a stereo interleaved file) and pull it back into Protools, it phase-flip-nulls out against the session to a satisfactory degree. If one channel was off by even a single sample that channel would clearly not null.

-R
Old 28th March 2003
  #20
Gear Guru
 
thethrillfactor's Avatar
 
4 Reviews written
🎧 15 years
Quote:
Originally posted by RKrizman
I doubt it. Whenever I do a bounce to disc (to a stereo interleaved file) and pull it back into Protools, it phase-flip-nulls out against the session to a satisfactory degree. If one channel was off by even a single sample that channel would clearly not null.

-R
Hey Rick,

A better test is the Spectrafoo Phase Torch.

It will show you if the 2 channels are off by any amount(even slightly).
Old 28th March 2003
  #21
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RKrizman's Avatar
 
🎧 15 years
Quote:
Originally posted by thethrillfactor
Hey Rick,

A better test is the Spectrafoo Phase Torch.

It will show you if the 2 channels are off by any amount(even slightly).
Pardon my ignorance about this, but is it possible for 2 channels to be off by less than a sample? It seems to me that 1 sample would be the "grid" so to speak.

In any case, I'va always been amazed, in lining up tracks to achieve a null, nudging one sample at a time, that in the space of 1 sample you go from clearly audible to dead quiet. Very disconcerting the first time I heard it.

-R
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