Sibilance/tin with some amps not others - diyAudio
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Old 18th March 2011, 02:15 PM   #1
Markgm is offline Markgm  United States
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Default Sibilance/tin with some amps not others

Hi,
I am curious about this from the amplifier angle. I am finding discussion on sibilance problems in the speakers forums, and I wanted to ask about this here.

I have a pair of speakers, two-way, with vifa 8" woofer and 1" tweeter, and have had since 2000. The number of amplifiers that I can hook up to these without excess sibilance/tin in high vocals and symbols and the like seems like half. Half do and half don't.

I was wondering if it might be possible to track down what it could be. I am listening to a tripath that has fantastic resolution, but has this going on with this speaker.

I know my brother's old heathkit amp doesn't do this with this speaker, nor did my old denon pma2000r. I had some of this with an Odyssey Stratos, a Marantz 7002 AVR, and I am having this with a tk2050-based amp. Not with a Proceed. Not more than the standard "clinical sounding" line with Bryston (close). I don't recall more than a tad of this with the Rotel RB-1090, or the NAD C-370.

TIA,
Mark
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Old 18th March 2011, 10:31 PM   #2
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There many discusions about this.
Whether it is a harmonic distortions or a frequency compensation issue I wouldn't be able to tell you.

But it is my opinion that it is this issue that gives one a false since of the amplifier being more acurate or not.
Especialy class d ones.

There are many here that are much much more experienced with that design.
I am not,but, I am also interested in what others have to say about this issue as well.
Good luck. jer

p.s. What I don't undertand is if the technology is so prefect then why is everbody being compelled to have too modify that very same amplifier!

Last edited by geraldfryjr; 18th March 2011 at 10:37 PM.
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Old 18th March 2011, 11:34 PM   #3
Markgm is offline Markgm  United States
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Have you experienced this more-so with class D?
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Old 19th March 2011, 12:04 AM   #4
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One of the pro amp designers on here discussed a test of amps on here: a 15khz + 19 khz intermodulation test. This is up in the range where sibulance occurs. This is not a published spec on any amp I have seen, but would be very interesting to me. Amps that don't respond this high in frequency obviously would not fail this test, but they would fail a flat frequency response test. The published IM distortion measurements, where available, involve I believe mixing 1 khz and some other frequency. Intermodulation distortion involves the production of sum and difference frequencies of the two test frequencies, divided by the actual frequencies it is supposed to generate.
None of my current amps have this sibulance. Music that has energy in these frequency ranges include top octave piano (elite brands) cymbals, trangles, other percussion with significant high frequency components. My favorite amp test record, Peter Nero "Yound and Warm and Wonderful" has a top octave piano solo on one cut. Very instructive to compare this to an actual Steinway piano. My St70 is currently good at that portion, but has some honkiness (Harmonic distortion) in the mid piano octaves, that is the middle frequencies. This correlates to the 1% HD spec of the magazine tests of the amp.
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Old 19th March 2011, 12:14 AM   #5
Markgm is offline Markgm  United States
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I have tried (limited-ly) to measure frequency response of this speaker, to get what looks like a bump from 5-7 KHz, only a half-octave there (like +10 dB there), and a tweeter roll-off starting around 17.5-18 KHz. I can't hear above 16 KHz, but this sibilance sounds fully evident to me.
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Old 19th March 2011, 01:06 AM   #6
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Quote:
Originally Posted by Markgm View Post

I have a pair of speakers, two-way, with vifa 8" woofer and 1" tweeter...
What is the crossover frequency and what order?

Regards
Mike
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Old 19th March 2011, 01:07 AM   #7
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I don't particular have any extensive experience with class d amplifiers persay.
But this this effect is very prominet in cd's ,cd players and sound cards as alot of them use the same form of conversion, pulse width modulation.

One example is queens "Tie your mother down" comes out like (ssssstdie your mohzssser stown" the analog album does not sound like that at all,
I have heard very few 16 bit cd players duplicate this correctly.

I am very critical and choosey when it comes to sound as I have been in the (and have a)recording studio aspect for a number of years.

I once tried an expreiment to eq it out and dump it to analog tape.
This smoothed it out quite nicely but I could not get rid of the sibilance as it was part of the orginal signal.

This is where the 24bit format with a higher sample rate execels.

So this leads me to my next question: what is the source of the material that you are trying to compare analog or digital?

This would be a very good test.
Exclueding dynamic range and SNR from the result of course.

As the amp may very well be working correctly but over emphasizing some of the nuances from the source and/or source material.
I hope that helps. jer

Last edited by geraldfryjr; 19th March 2011 at 01:11 AM. Reason: spelling
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Old 19th March 2011, 01:51 AM   #8
Markgm is offline Markgm  United States
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Quote:
Originally Posted by Michael Chua View Post
What is the crossover frequency and what order?

Regards
Mike
A friend helped me look at the parts in the x/o and measure them. We measured one 2.2 mH coil in series on the low pass, and another across the tweeter. With a 4-ohm resistor and a 6.8 uH cap in series on the tweeter, and a 8.2 uF cap across the woofer.

The Vifa drivers are:
Woofer: P21WO39-08 8" poly cone, 40mm voice coil
Tweeter: D27TG45-06 1" textile dome - bulged faceplate - chambered

I also found my old sine wave tests 20-20K, and the bump was more-so from 5 Khz up to nearly 10 KHz (not 7 KHz, sorry).

Last edited by Markgm; 19th March 2011 at 01:57 AM.
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Old 19th March 2011, 02:04 AM   #9
Markgm is offline Markgm  United States
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jer,
For me, this is on half of my recordings. I think this is more-so the case with CD as well. I haven't had a working record player in 6 months right now. It is simply when it gets to vocals - the Ss, and high vocals very often, and symbols, and high treble sounds like that.
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Old 19th March 2011, 02:39 AM   #10
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Very good,keep posting on any thing else you may find.
I have said before that I very much am found of class d but it is still very much in its infancy. jer
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