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Old 4th April 2008, 10:28 AM   #1
wixy is offline wixy  Australia
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Default Fostex Sibilance?

Don't get me wrong, I enjoy the sound of my FE206E's (modded with phase plugs, basket damping and earthed negative terminal). However, i do notice a lot of sibilance, both with cd's and lp's. It can be really annoying at times.

Is this just a Fostex trait?
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Old 4th April 2008, 10:35 AM   #2
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Can't say I've noticed it myself to any significant extent when listening 206s. The plugs should put a hole in the FR across that region, reducing potential issues anyway. So it might just be that it's revealing sibilance on the recording. A lot of female vocals in particular suffer from it. You could try a notch or shelving filter if its bothering you.
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Old 4th April 2008, 10:52 AM   #3
MJK is offline MJK  United States
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You really need a BSC filter, it will attenuate the top end and eliminate the sibilance. Sibilance is a clear indicator of an unbalanced SPL response, the top end is rising relative to the bass and mid-bass.
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Old 4th April 2008, 11:26 AM   #4
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Without a degree in advanced maths, how can you calculate or guesstimate the values for a BSC?

Fran
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Old 4th April 2008, 11:41 AM   #5
MJK is offline MJK  United States
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There is an Excel spreadsheet on my site and a link to an on line calculator. Both can be found under the General Speaker Related Articles link.
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Old 4th April 2008, 12:42 PM   #6
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Sibilance is a fact in most female voice recordings.

I have gone to a computer front end using Foobar 2000 as my player. One of the plug-ins I installed is a spectrum analyzer. I spend a lot of time looking at the music. You learn some weird and wonderful thing, like the harmonic structure of various instruments and the power spectrum of the human voice.

Funny thing. Operatic sopranos produce very little energy above 4-5kHz. Jazz singers however, produce gobs and gobs of energy in the 5-7kHz range. This is sibilance. It is there and it is real. If you are paranoid about producing exactly what is on the CD or LP, then you will have to live with sibilance.

Funny thing 2. If you are using a driver with a seriously rinsing response (FEx06E, Lowther DX3 and DX4, etc.) you are going to exaggerate the sibilance. These drivers will be bright because of the elevated response above 1kHz, but classical and jazz instrumental don't have all that much energy above 5kHz, so you don't notice it so much, just more "air". But a spitty singer becomes unbearable.

What can you do about it? You need filters. Now if you can't bring yourself to use filters, then stop reading and learn to live with it. For the rest of you, first you need a BSC to bring down the highs to the level of what is below 300-500Hz. Second, you may or may not need some series resistance to flatten out the rising response. A lot depends on you amp. Finally, with the Lowther's and anything else with exaggerated response in the 5-7kHz range, you need a notch filter.

Since I use a computer front end. I use the equalizer built into Foobar 2000. It is not a true 1/2 octave equalizer, but close enough. (I am looking for a better equilizer.) I just crank in what ever is needed to flatten the response. No passive filters!

Does this digital EQ degrade the sound? Technically, for sure. In reality, maybe. Certainly no more than an external equalizer or passive filter. The advantage of a balanced response far outweighs any signal degradation.

YMMV, but that's my story and I'm sticking with it.

Bob
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Old 4th April 2008, 01:18 PM   #7
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Thanks Martin et al.


I've just built some fonkens (enabled fe127) and at first they had a skewed response that left me without bass and sore ears. The baffle on these is quite narrow - maybe 135mm (can't recall the exact figure right now).

On a guess I added some polyester filling to the speakers and it improved things a lot. Then I tricked about with a resistor in series with the + lead. I tried 5, 7.5, 9.7 and 15R - of these with 5 it was still harsh and 9.7 and 15 tended to rob the dynamics and life out of the speaker. 7.5 seems pretty good to my ears, with maybe still a tendancy towards being bright - although some would just call it revealing. It would still tend towards sibilance - I don't think nina simone at town hall would sound good on this for example!

So my question now is if the R in series works, should I purchase a 1.5mH inductor and trick about with this again? Maybe a little more filling might do the job and leave it at the resistor only? Decisions decisions!

Fran
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Old 4th April 2008, 01:45 PM   #8
Kensai is offline Kensai  United States
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I live by the digital EQ in the PatchMix app that runs my E-mu 0404, especially since I spend most of my listening time with small OBs. To my ears, the only situation where SQ can be superior to my EQ stacks in PatchMix is upsampling to 176.4kHz. Thing is, PatchMix can't apply EQ when sampling is above 48kHz, so I lose alot of bass response. Funny thing is the top end (I'm using Pio B20s with no tweeter) seems to be fine, maybe better than non-upsampled with EQ, and the rest of the range, other than the bottom seems as smooth or smoother, too.

Some interesting things can be done in the digital domain, often without negatively impacting SQ.

Kensai
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Old 4th April 2008, 05:20 PM   #9
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Ok,

I don't have all the components for the zobel network but I am going to have a crack at making an inductor tonight.

So my values then would be 7.5R and 1mH in parallel. What do you think?

Fran
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