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Tone Controls/Graphic EQ?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote tg Quote  Post ReplyReply Direct Link To This Post Posted: 18 Nov 2008 at 1:40pm

Analog Kid,

http://www.enjoythemusic.com/magazine/equipment/0101/behringer8024.htm 

this is the article I referred to earlier, it addresses exactly the issues you raise.

The unit reviewed is obsolete and has been replaced by the DEQ 2496 - it offers many options for programmed preset equalisation curves for either room/speaker correction or the taming of difficult recordings.

The learning curve is rather steep but the unit is exceptionally powerful and relatively inexpensive.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 19 Nov 2008 at 6:04am
Here's a comment pro-tone controls...

Whilst researching cross-feed for professional headphone use (because we have an enquiry with us at present for that sort of use), I wanted to figure out the relative level of what the left ear hears from the right speaker, and vice-versa. To answer this enquiry didn't require an in depth scientific explanation of hearing and psychoacoustics, just that the enquirer needed some opposite channel "sidetone" in each ear - simple?

Therefore "at what level?" was the question I needed to answer. I model things in a mathematical way and the dominant "feed" to the opposite ear is the most direct reflection off the nearest wall. By using a typical room model (a sketch on paper) and knowing the 6dB per doubling of distance rule, I was able to calculate that it's around -20dB, therefore requiring -20dB of "sidetone" from the opposite channel to satisfy the enquirers wish.

But what about absorption of the "nearest wall" at different frequencies? Well, a plastered brick wall gives pretty constant absorption end to end (my reference tables said so), and therefore I modelled the required mod to a Solo based on that. It's headphones after all (meaning, the listener will hear as if he/she were in a room with plastered brick walls).

However, then I thought about real speakers and different walls. Modern homes tend to use plasterboards for reason of economy. So I looked up plasterboards in the tables. Shock and horror! Plasterboards absorb a ton of bass! In fact, end to end we have a 10dB (approx) slope that favours the treble end! I don't live in a plasterboard home, but the workshop is plasterboarded and it sure sounds bright in there!

Therefore, the only way I can think of equalising such a room is using tone controls.

That old argument about tone controls upsetting phase can be thrown out of the window if you consider that any frequency dependant attenuator alters phase. Yes, plasterboards alter phase - if they didn't there would be no "slope" to the response. Phase and frequency are inseparable!

Thus, the phase IS going to be OUT using a flat amp in a plasterboard room. Now if tone controls were adjusted to counter the "slope" then the phase is corrected!

Bang goes another old HI-FI journalism myth!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Analog Kid Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov 2008 at 10:43am
There are two different solid-state amps I am fancying. Both have tone controls. One has turnover frequencies of 300 Hz for the bass and 3 kHz for the treble. The other has adjustable turnover frequencies of either 40 Hz or 100 Hz for the bass and either 8 kHz or 20 kHz for the treble.

Which is more useful? Or does it depend entirely on the type of music I am listening to?



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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov 2008 at 4:30pm
Hmmm, more info please!

Turnover frequency and boost/cut frequency are two different things. I'm pretty sure the second one refers to boost/cut? Either that or you've just discovered one of those manufacturers I was on about... Ermm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Analog Kid Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov 2008 at 6:59pm
Originally posted by Graham Slee Graham Slee wrote:

Hmmm, more info please!

Turnover frequency and boost/cut frequency are two different things. I'm pretty sure the second one refers to boost/cut? Either that or you've just discovered one of those manufacturers I was on about... Ermm


Oh yes, I mean boost/cut frequency, but the manufacturer calls it "turnover frequency" in their product catalog. So anyways, to sum up: the tone controls of the first model boosts or cuts at 300 Hz and 3 kHz for the bass and treble respectively, and the second model is capable of boosting or cutting at either 40 Hz or 100 Hz for the bass, and either 8 kHz or 20 kHz for the treble. Also worth mentioning is that the first one has a boost/cutting range of +/- 10 db, whereas the boosting/cutting range of the second amp is +/- 8 db.

Here it is:

http://www.accuphase.com/model/pdf/e-450_e.pdf

http://www.accuphase.com/model/pdf/c-2110_e.pdf


First one is an integrated amplifier and second one is a preamplifier. Both are 100% solid-state. In each PDF catalog scroll down until the last page where the technical specifications are listed. There you will find the boost/cut frequencies for the tone controls.

So which one is more useful?




Edited by Analog Kid - 23 Nov 2008 at 7:13pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 24 Nov 2008 at 12:34am
SOS!

Sense of Specs!

Making sense of specifications



Question: What is meant by turnover frequency?

Answer: The frequency at which things start to change.

     The turnover frequencies are indicated by the (inner) dots marked fLB (bass) and fHB (treble).


Question: What is meant by the boost (or cut) frequency?

Answer: The frequency at which the maximum boost (or cut) occurs.

     The boost and cut frequencies are indicated by the (outer) dots marked fL (bass) and fH (treble).

     Where the curve starts to flatten out after its "climb" or "fall"


The specification for the two amplifiers AK asked about are not written very well. I think it's a case of the manufacturer knows what its doing but isn't very good at communicating it.




This explains that the turnover frequencies - the frequencies at which things start to change - are selectable but doesn't actually say what they are.

It shows that the frequencies which maximum boost or cut occurs at is 40Hz or 100Hz (bass) and 8kHz or 20kHz (treble)

And the maximum boost or cut is 8dB.




This explains that the turnover frequencies - the frequencies at which things start to change - are 300Hz and 3kHz.

And that the frequencies which maximum boost or cut occurs is 50Hz (bass) and 20kHz (treble).

And the maximum boost or cut is 10dB.

Please say you understand this???

I'll leave it up to you to choose which one to buy based on your new knowledge.




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Post Options Post Options   Thanks (0) Thanks(0)   Quote iamalexis Quote  Post ReplyReply Direct Link To This Post Posted: 01 Aug 2009 at 7:33pm
i was thinking about tone controls the other day. i'm into the idea of a simple set of tone controls (unfortunately my amp doesn't have any). the reason for thinking about them is because i have just moved into a new place and the room my hi-fi is in gives a bass boost at around 100hz. if the tone controls were to have a true by pass then i wouldn't have a problem using them in my system.
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