jitter reduction?

I'm not saying DSPs are bad. They have their place in audio. For HT.. DSPs are great! None of them I've heard do well with 2 channel music. I owned Meridian and friend owns Lexicon. Dealer friend carried McIntosh and now carries Anthem DSPs. I've heard quite a few over the years.

I'm not totally against DSP. I've recently been playing with the idea of buying a second pair of speakers that use active crossovers. I would of course still use the analog inputs of the active crossovers and a analog style preamp.

The Dacs in these units at least IMHO still leave something to be desired in musical enjoyment. Now if someone can talk Steve into modding the digital crossovers and offering it at an affordable price for the average Joe(like myself)..we're in business! LOL

All I can say is you'll have to put the papers down some day and listen for yourself.From your statement "there are a lot of DSP amps out in the market today in HT setups"...you are correct..key word being HT.

Good listening

Shadorne, thanks for your above post, gotta love objective measurement.

The threshold of audibility for pure tones was found to be about 10 ns rms at 20 kHz and higher at lower frequencies.

I would like to seek your opinions on the above, though.

1. I am gong to assume that Dolby typically has experienced (read, greybeards;)) and to listen for audibility at 20kHz and on a pure test tone, would seem to be counterintuitive. Firstly, high frequency hearing goes down with age and you really have to crank a 20kHz tone up, to hear it, were they trying to perform a "worst case" secenario? But the above makes sense as they do say it is higher at lower frequencies.

2. Secondly, why do it with a pure test tone, when we react to complex waveforms in another manner, and music is, of course made of complex waveforms so I am surprised they didn't use a beat frequency oscillator or any other complex waveform. Do you have input on that?

3. If the threshold of audibility was indeed higher at lower frequency, why not take most of the tests at 1kHz, right in the middle of the curve?

Not attacking you nor their tests at all. I have been an executive for so long, and off the test bench, that I am just curious if you knew?

Now, unless I am missing something, when I look at Atkinson's Miller Suite data,it seems about 250pS PEAK is where he draws the line on good/bad DAC performance, which means, if I am understanding this correctly, that virtually any audiophile DAC is an 100X better approximately than what they say is the hearing threshold..Yes? No?

Thanks,
C

Gmood1 - I have a Proceed AVP. No problem hearing the effects of jitter on this one. It beats the Lexicon hands down. It's so good that I have not bothered to mod it. I dont listen to music on it anymore, only movies.

As for the crossover, I do mod the DEQX, but it is expensive. In the future, I wil be doing fewer mods, not more. My own products take up most of my time now.

Steve N.

Chris,

The authors found experimentaly through listening tests that pure tones made it easier to detect jitter. They looked at all frequencies not just 20 Khz. The paper is a mix of mathematical modelling and lab measurments and lab listeting tests. Jitter creates sideband intermodulation distortion - new frequencies appear as the jitter frequencies modulate the musical or primary signal. According to the paper, the best way to hear distortion is to get the sideband distortion in the ears sensitive 1 to 4 Khz range whilst keeping the music outside this range so there is as little masking as possible.

I'd strongly recommend to download and read it if you are interested - refreshingly absent of any formulas and complex mathematical jargon that you often see in AES papers. They used headphones in listening tests so loud speaker distortion was not an issue (most loud speaker distortion would probably make it even harder to hear jitter)

The important thing to walk away with is that it still recommends that you should always keep jitter as low as possible as distortion is cumulative...what might not be audible distortion from one root cause can accumulate with other non-linearities to become audible.

Shadorne, thanks.
c