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#44798 - 01/27/03 09:23 PM Re: A Q about phono stages & the 950
Jason J Offline
Desperado

Registered: 09/02/02
Posts: 615
Loc: Northern Garden State
Censor? Hmm...

I do apologize if I came across harsh. It's true I've always have been more of an analog fan. It's just that I've never heard of a record being described in "bits". Nor do I understand how you can claim a record can be of a lower resolution than a redbook CD? I would actually would love to hear your reasoning behind either of these ideas.

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#44799 - 01/27/03 09:33 PM Re: A Q about phono stages & the 950
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
Sure. I'm just a little gun-shy about confrontation in this forum lately....

Basically each bit in a PCM data word gives 6db of S/N ratio (in theory) and it takes a very good LP to achieve anything around 60 db S/N ratio (IIRC) so at least from a bit depth standpoint that's pretty much it, allowing for similar QoI in both systems of course.

Sample rate vs. bandwidth is a whole other discussion and has nothing to do (other than consuming bandwidth) with the above discussion. In any case, something like 11 bits at an adequate sample rate should give slightly better than LP performance.

One other thing - in the world of analog formats LP isn't near top dog. Good analog can be very, very good, but also very very big, expensive and so on.

I'm not an expert on analog stuff and I'm sure (once a cease fire is called ) there are others here who can certainly speak with more authority on those formats.
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Charlie

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#44800 - 01/27/03 10:06 PM Re: A Q about phono stages & the 950
soundhound Offline
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Registered: 04/10/02
Posts: 1857
Loc: Gusev Crater, Mars
Charlie is right on that analog can be very good - as a matter of fact, there are mastering tape machines that run at 30 inches per second and use 1" wide tape for mastering two track stereo. Such machines give even 24 bit digital a good run for the money in some aspects. In other aspects, digital has it all over analog. One of these is modulation noise in any tape recording system, another is the somewhat lacking bass response of tape, especially as the tape speed gets as high as 30 i.p.s. Both have trade-offs that must be weighed when working at such levels of precision.

12 bits is actually pretty darn good - that CD that I circulated (and got me put away in a Mexican jail for copyright infringement ) proves this fact.

I have actually been questioning however if analog noise floors and digital ones can be compared, even somewhat directly. It can be proven that with the addition of dither to a digital word, it is possible to hear below the theoritical noise floor limit for a particular word length. Gonk has a CD that I made that proves this fact (it has test signals I made myself, so there is no danger of me ending up in the slammer again ) But there has to be a limit to how much can be done when adding dither to the least significant bit of a digital word. There has to be a downward limit, below which nothing can be perceived.

Analog however does not have any theoritical lower limit of resolution. The signal just continues to be submerged further and further into the noise floor.

I guess a test could be devised to determine just how much difference there actually is, but personally, I'd rather go out for pizza.

Anyway, I'm open for discussion on this subject.

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#44801 - 01/27/03 10:47 PM Re: A Q about phono stages & the 950
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
The difference in practice between a theoretical limit and a real limit is, of course, immaterial...

At some point the original signal becomes hopelessly obscured for all intents and purposes and even if you give a few orders of magnitude away digital (well implemented) still comes out smelling like a rose. I do think digital has some time to make up before the level of sophistication is reached that analog systems have simply due to the years of effort that have gone into maturing them, but I think digital is getting there.

I still maintain that most of the issues with redbook CD are QoI and not actual limits of the format. The human ear has finite resolution, once we can resolve below the width of a hydrogen atom there's no more to listen to.

Just IMO and YMMV, etc.
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Charlie

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#44802 - 01/27/03 11:08 PM Re: A Q about phono stages & the 950
soundhound Offline
Desperado

Registered: 04/10/02
Posts: 1857
Loc: Gusev Crater, Mars
Quote:
Originally posted by charlie:
The difference in practice between a theoretical limit and a real limit is, of course, immaterial...


Yes, of course. I just have a gut feel that the signal will hold on below the noise floor a bit farther with analog than it will with dithered digital. I really don't think it matters much in the real world as there are more important considerations in both formats. On the CD that gonk has, I created a whole bunch of stimuli including reverb tails that were originally 24 bit and reduced them to 16, 12 and 8 bits. It is absolutely amazing to hear the sound continue through the noise floor (from the dither) and fade to inaudibility on the 8 bit examples. When dither is omitted, the sound gets very, extremely ragged and then drops off suddenly to nothing.

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#44803 - 01/27/03 11:54 PM Re: A Q about phono stages & the 950
Jason J Offline
Desperado

Registered: 09/02/02
Posts: 615
Loc: Northern Garden State
I've worked in studios where 2" analog is a format option. It is very, very expensive compared to digital formats. However, there is a warmth on the analog side that really isn't explainable using specs. After an eight hour session with analog, I didn't have a headache. After a few hours with digital, my head was pounding. This isn't scientific at all, but just feeling. Feeling that something was missing in the digital that was there on the analog version.

I still have an issue with the idea of converting a record to digital. True, it would be great for archiving purposes, good for noise restoration on the proper system, and certainly more convenient. The problem arrises in the idea of a DAC inside of an inexpensive phono preamp. There's a reason why major and minor studios use mega-buck outboard converters. (Interesting side note: It's really amazing to read about how many digital users like to put their mix through analog at least once during the recording stage.) Just as there is good and bad analog, there is just as good digital compared to bad digital. IMHO, for an average home listener to get the best experience from their vinyl collection, keeping it in the analog domain is their best option.

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#44804 - 01/28/03 12:38 AM Re: A Q about phono stages & the 950
soundhound Offline
Desperado

Registered: 04/10/02
Posts: 1857
Loc: Gusev Crater, Mars
Jason:

I am constantly amazed whenever I see "24 bit / 96Khz" analog to digital and digital to analog converters that sell for $150.00 or something like that. Really, just how good could they be??

I have in my studio a vintage vacuum tube compressor/limiter made by Collins Radio back in the 1950's. It uses basically the same circuit that the famed Fairchild limiters that the Beatles used on most of their albums. I use it quite a bit to put vocals and dialogue through. In goes crap, out comes ELVIS, 1954!!

Here's a picuture of it:



[This message has been edited by soundhound (edited January 28, 2003).]

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#44805 - 01/28/03 10:24 AM Re: A Q about phono stages & the 950
Philip Hamm Offline
Gunslinger

Registered: 08/29/01
Posts: 93
Loc: Northern Virginia, USA
Quote:
I have a low output Sumiko MC cartridge. Even though the Rotel is set up for MC operation, I find my system sounds better with a Levinson phono pre/preamp ahead of the Rotel. Then I run the Rotel in MM mode.
Wouldn't that run the RIAA curve twice? Seems dubious at best to me as a vinyl fan to run two phono preamps.

Charlie, s/n is only one part of the equasion. Your assessment that vinyl resolves to about 12 bit is very simplistic and only involves one of many factors in creating good audio. S/n is vinyl's achilles' heel, for sure, but the music above that noise level can be at least as precisely resolved than redbook CD (IMO - assuming a good record).

------------------
Philip Hamm

[This message has been edited by Philip Hamm (edited January 28, 2003).]

[This message has been edited by Philip Hamm (edited January 28, 2003).]
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Philip Hamm

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#44806 - 01/28/03 12:27 PM Re: A Q about phono stages & the 950
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
Quote:
... s/n is only one part of the equasion ...


Of course S/N ratio is only part of the equation. It's exactly the part bit depth addresses, though. I always thought harmonic distortion at high output and channel separation were vinyls' weakness, maybe it has more than two heels?

12 bit is pretty good - don't get too hung up on the bit depth wars.
_________________________
Charlie

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#44807 - 01/28/03 01:18 PM Re: A Q about phono stages & the 950
bobliinds Offline
Gunslinger

Registered: 03/10/02
Posts: 221
Loc: Las Vegas, NV
Quote:
Wouldn't that run the RIAA curve twice?


Good catch.

But, in fact, it doesn't. The reason is that I'm not running the signal through two phono preamps. The Levinson device is just a head amp that raises the low output MC signal to a level that a MM phono preamp can process effectively. It doesn't run the RIAA curve.

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