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Old 1st October 2011, 08:35 PM   #11
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There is a foobar plugin that uses convolution and selects the filter kernel based on the track's tags.
Yet Another Convolver - Hydrogenaudio Forums
With convolution you can do as many eq bands as you want.
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Old 3rd October 2011, 09:19 AM   #12
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The adjustment I often like to make is a cut somewhere in the 8k to 13kHz range. This is to compensate for the "glassy" sound that arises from many female classical singers and the "grainy" sound of many a male classical singer. If anyone knows of a better way to deal with this I'd love to know. It's a problem that I've been aware of for my entire life, showing up on all systems I've ever had. As my system has got better, it sounds more and more like simple resonances in the upper band.
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Old 5th October 2011, 09:07 AM   #13
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Sox is the holygrail. You also might want to start learning Linux and the JACK audio system which would allow you to filter the output inline, amongst many many other things.

You can be absolutely precise with what filtering you want to do. You could happily chain 32 (or what ever number you want... there somewhere I read an upper limit) EQ levels. Some of the SoX effects are primarily intended to be applied to a single instrument or ‘voice’.


From the Sox page Effects

equalizer frequency[k] width[q|o|h|k] gain

Apply a two-pole peaking equalisation (EQ) filter. With this filter, the signal-level at and around a selected frequency can be increased or decreased, whilst (unlike band-pass and band-reject filters) that at all other frequencies is unchanged.

frequency gives the filter’s central frequency in Hz, width, the band-width, and gain the required gain or attenuation in dB. Beware of Clipping when using a positive gain.

In order to produce complex equalisation curves, this effect can be given several times, each with a different central frequency.

The filter is described in detail in [1].

This effect supports the −−plot global option.
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Old 5th October 2011, 09:23 AM   #14
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Quote:
Originally Posted by CastleJohn View Post
The adjustment I often like to make is a cut somewhere in the 8k to 13kHz range. This is to compensate for the "glassy" sound that arises from many female classical singers and the "grainy" sound of many a male classical singer. If anyone knows of a better way to deal with this I'd love to know.
Its classic sibilance you're describing. Do you find it on the recording (call up the wav file in Audacity to check)? If its not been introduced at that stage then the problem is almost certainly out of band interference from various sources, coming into and out of your various components via the grounds of your signal cables. Regrounding is one solution (rigorous adoption of star earthing within a component), power supply (including mains) filtering is another. I don't find its so common on recordings as professionals tend to use balanced signal cables which mitigates it. But I do have a couple of prized tracks to demonstrate it

Quote:
It's a problem that I've been aware of for my entire life, showing up on all systems I've ever had.
I reckon I lived with it for dozens of years without paying any attention. Then noticed it for certain in the past couple of years. Since noticing it, I've been chasing it down relentlessly...

Quote:
As my system has got better, it sounds more and more like simple resonances in the upper band.
Yes, I take it its intermodulation between HF energy and interference but I don't know why it always seems to have the signature you've described.
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Old 5th October 2011, 12:18 PM   #15
phofman is offline phofman  Czech Republic
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Originally Posted by reverse View Post
Sox is the holygrail.
It sure is
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Old 5th October 2011, 04:33 PM   #16
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Quote:
Originally Posted by abraxalito View Post
Its classic sibilance you're describing. Do you find it on the recording (call up the wav file in Audacity to check)?
I haven't got Audacity. For some reason I thought it had to be paid for, but I see that it is actually free. I'll try it out and report back in due course.

I'm surprised by what you say about interference. I did have a serious problem with radiation from the rectifiers in my power amp. When I changed to a Musical Fidelity CD player it made occasional random dropouts - which ceased when I put 4x100nF capacitors across my amp's rectifiers - so I guess that was pretty bad. Maybe there is some residual? I do use a mains filter.

As far as grounding is concerned, the amp is strictly star-grounded. My DAC is supposed to be earthed but I've tried de-earthing it (making everything floating) but that makes no difference.

John
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Old 6th October 2011, 03:49 AM   #17
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this is one of the best free Parametric EQ's i have found so far it is a VST type.


KVR: Christian Budde Noname-EQ - Virtual Effect

JER
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Old 6th October 2011, 04:16 AM   #18
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Quote:
Originally Posted by CastleJohn View Post
I'm surprised by what you say about interference.
Yeah, I was surprised to discover it too.

Quote:
I did have a serious problem with radiation from the rectifiers in my power amp. When I changed to a Musical Fidelity CD player it made occasional random dropouts - which ceased when I put 4x100nF capacitors across my amp's rectifiers - so I guess that was pretty bad.
Yes I had a audio design which used a bridge rectifier which failed conducted EMC testing because of just that. I prefer to use snubbers these days to absorb the RF rather than just recirculate it. Having an amp's rectifier noise affect a CD player is really something

Quote:
Maybe there is some residual? I do use a mains filter.
What kind of mains filter may I ask?

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As far as grounding is concerned, the amp is strictly star-grounded.
Are you sure its really really strict? Just as one example, Doug Self violates strict star grounding (in his book) at one place that really does make a difference to the sound - the input.

Quote:
My DAC is supposed to be earthed but I've tried de-earthing it (making everything floating) but that makes no difference.
What kind of transformer does the DAC contain? Does it have its own dedicated mains filter - internal or external?
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Old 22nd October 2011, 03:31 PM   #19
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Interesting questions, abraxalito. Sorry I've been so slow to respond.

I'd be interested to know more about your snubber arrangement.

My only possible doubt about star grounding is at the input. To eliminate hum (because the PSU is in the same unit) I take a twisted pair from the RCA socket, which is isolated from the grounded chassis. This takes the input signal to the PCB, accompanied all the way by the ground, with the ground wire then bent back to the star point without making contact with the PCB.

Audacity has proved there is recorded sibilance on some recordings, others just show an excessive top end but without specific peaks. It is these latter ones I find most troublesome. Some sound as though there is very significant sibilance around 11-12kHz, requiring -18dB or so of cut to eliminate (using foobar's 31 channel graphic equalizer).

My DAC is a Benchmark DAC1 and I don't know what sort of PSU it's got. Input to DAC is by optical fibre.

I'm thinking about further quietening the rectifier emissions by a 0.5 ohm resistor in the power circuit to the reservoir capacitors. Do you think that would be worth trying? It will reduce the voltage by a volt or so but I'm not worried about that.
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Old 26th October 2011, 03:59 PM   #20
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Quote:
Originally Posted by CastleJohn View Post
I'd be interested to know more about your snubber arrangement.
These days I'm using a 1uF Z5U ceramic (50V) in series with 47R across each diode.

Quote:
My only possible doubt about star grounding is at the input. To eliminate hum (because the PSU is in the same unit) I take a twisted pair from the RCA socket, which is isolated from the grounded chassis. This takes the input signal to the PCB, accompanied all the way by the ground, with the ground wire then bent back to the star point without making contact with the PCB.
That sounds fine, doesn't violate the star grounding.

Quote:
My DAC is a Benchmark DAC1 and I don't know what sort of PSU it's got. Input to DAC is by optical fibre.
Judging by the pictures Google found it has a toroidal, so moderately high capacitance to mains. Not easy to tell if there's any mains filtering going on behind the shroud over the mains inlet - my guess is not. So there's a potential culprit for sibilance.

Quote:
I'm thinking about further quietening the rectifier emissions by a 0.5 ohm resistor in the power circuit to the reservoir capacitors. Do you think that would be worth trying? It will reduce the voltage by a volt or so but I'm not worried about that.
A resistor like that will tend to dampen down ringing on the secondary of the transformer and tend to reduce higher order harmonic magnetic coupling in to the rest of the circuit but do little to quench rectifier emissions methinks.
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