High End Tone Control

[EUVL]

Further to this discussion on EQ & Tone Control:

http://www.diyaudio.com/forums/anal...rch-preamplifier-part-ii-293.html#post2662376

I open a new thread to continue the discussion.

Thorsten, the stage is your ....


Patrick

 

[EUVL]

I made some search in google JP but could not find anything meaningful.
Could you give us a few pointers, if only to kick start the discussion ?


Thx,
Patrick

 

[EUVL]

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[analog_sa]

Assuming digital sources, isn't an analogue device achieving this a complete waste of time and effort?

 

[EUVL]

Good question. But what to do with tapes and LPs ?

And how to do it digitally (e.g. real time or off line) ?
Do we lose resolution (or more abstract SQ) in the process ?


Patrick

 

[Groove T]

Assuming digital sources, isn't an analogue device achieving this a complete waste of time and effort?

Digital is not perfect and Microphones and Loudspeakers are almost analog, so why not.
Second there is always the discussion, which pre amplifier sounds best or not and why this is the case.

And there is the question, how are the masters mastered and equalised ( anolog or digital) and what is the resulting sound quality.

For analog Records with have different equalisations, giving different sound balance and with 25 year old CDs the soundmix is also often very bright, since they wished to demonstrate the clarity of the newdigital medium.

 

[kevinh]

Rip the Disc's and Taped into a loss less digital format, 192/24 bit and then eq the program material using software on a computer. A good phono into A/d is needed.

There are good solutions for the cpu software-> USB -> I2S -> FIFO buffer _> D/A -> Amp

D Burwen has put the functionality of the Cello Audio Pallette into software (plus other functions, he was the designer of the Pallette).

BB_Home

This software is implemented as a Windows Media Player plug in (the DSP functions are encoded in Excel Spreadsheets) Windows has a loss less media file format. I have also installed a FLAC plug in for Windows Media Player. The settings for each recording can be stored so you only have to do the adjustment once for each recording.

Then for conversion from USB to I2S there is the exaU21 board.

http://www.exadevices.com/

The FIFO buffer project being done by iancanada on this thread, great looking project.

http://www.diyaudio.com/forums/digi...ifo-project-ultimate-weapon-fight-jitter.html


The Buffalo Dac from twisted pear or the RAKK Dac from K & K.

This would provide a wonderful digital front end to allow people to master their own music library to work with their system. As opposed to the system used by the recording engineer.


The flexibility we are just beginning to get to allow us to control our music libraries is a wonderful thing for DIY music lovers. IMO.


I had occasion to hear what the original Audio Pallette could do for records, having this capability abailable for 10% of the cost of the Palette (25 years ago) is amazing to me.

 

[Bonsai]

A well implemented Baxandall tone control is a wonderous thing. Feed it with a low source impedance and be circumspect about the boost and cut (20dB is easy to achieve, but 10dB is a better design goal) and they can add a lot to a system.

See Self's 'Small Signal Audio Design' for some good examples.

(I designed quite a few pre-amps in my 20's and always included Baxandall T/controls but my recent designs have not included these. Might be time to take a trip down memory lane again)

 

[wahab]

A well implemented Baxandall tone control is a wonderous thing. Feed it with a low source impedance and be circumspect about the boost and cut (20dB is easy to achieve, but 10dB is a better design goal) and they can add a lot to a system.

Undoubtly , the best solution...

It should be mandatory in any serious preamp design , along with a defeat switch.

 

[Pano]

Tone controls are for sissies! Like putting milk and sugar in your coffee. Wimps.

 

[Bonsai]

I like cappuccino, with an extra shot and three sugars. Rich, dark and sweet with a good head. Beats a straight 'tough guy' brew every time.

 

[KSTR]

Bass and treble tone controls are as essential to me as the volume control, given the wide variety of bass content in recordings from a 50yrs span and the changing sensivity of the ear vs SPL level, to a lesser extent the same I find valid for the high treble. A +-6dB Baxandall with wide spead corner freqs does that nicely. Still there is need to balance out the overall tonality sometimes and then a tilt-type tone control which tilts up/down the response along straight lines, flattening out at the above corners. For a few dB's of range again a Baxandall works, and for cut only range a passive version with 2..3 RC's will do.

That said I must admit that at home I do most of the 'personalized' EQ with the mentioned equalizer plugin in the digital domain on top of the already sligthly tilted down acoustic target (remember the flat-is-not-correct thread?) of the DSP correction, only the basic bass control is done analog, partly because bass boost tends to eat up digital headroom. Some of that 'voicing' has to do with speaker principle and my likings (dipoles are benign when dialing in too much bass content to counteract the 'lack of punch' vs box speakers, due to the much cleaner time response. The lack of punch is often a recording artifact when the sound engineer used boomy speakers and/or rooms, it occurs to me).

- Klaus

 

[kevinh]

The Fletcher Munson curve should be built into software tone controls.

 

[Cobra2]

The Fletcher Munson curve should be built into software tone controls.

Would this equal the "oldschool" loudness?

 

[wahab]

Would this equal the "oldschool" loudness?

Along with a Baxandall , a traditionnal loudness should also
be mandatory in any high end design...

 

[Pano]

I actually like loudness controls, properly done.

But I do have to say, the better and more balanced my systems gets, the less I feel a need for tone controls. Don't use the volume control as much either. Go figure.

 

[kevinh]

I actually like loudness controls, properly done.

But I do have to say, the better and more balanced my systems gets, the less I feel a need for tone controls. Don't use the volume control as much either. Go figure.

Depends on the recordings you listen to.

 

[EUVL]

A couple more links that I found :

http://www.forsselltech.com/media/attachments/Evolution_of_an_EQ_Design2.pdf

Filter Bank Using Graphic Equalizer IC ƒAƒiƒ�ƒO“dŽqŠyŠí‚̉ñ˜H‚ð“Ç‚Þ/ƒEƒFƒuƒŠƒuƒ�ƒO
Filter Bank Using Graphic Equalizer IC Pt.2 ƒAƒiƒ�ƒO“dŽqŠyŠí‚̉ñ˜H‚ð“Ç‚Þ/ƒEƒFƒuƒŠƒuƒ�ƒO
Filter Bank Using Graphic Equalizer IC Pt.3 ƒAƒiƒ�ƒO“dŽqŠyŠí‚̉ñ˜H‚ð“Ç‚Þ/ƒEƒFƒuƒŠƒuƒ�ƒO

http://douglas-self.com/ampins/wwarchive/wwarchive.htm#baxtc


Patrick

.

 

[bbggg]

Go figure

Actually it is not that difficult to go figure. Bass behavior is next to impossible to predict, what with room dimensions and acoustics varying so widely. Building methods alone (drywall vs bricks and mortar, for example) produce huge differences in the way bass interacts with a room. The more so since the vast majority of people cannot audition speakers at home before they buy. A simple way to vary bass level, even slightly so, is imperative for SQ optimization. Active speaker manufacturers know about and provide for this. Passive speaker makers don't, because it can't be done electrically without screwing everything else up. The onus is upon amplifier makers, but most seem to subscribe to the erstwhile AT&T mentality ("We don't care, we don't have to").

 

[kevinh]

I think that bass issues are better dealt with using multiple subs if possible. Discussed in this thread. This tends to even out the bass response as much as possible. Then some eq can be applied. Generally it would be better to use tone controls for program correction rather than correcting room/speaker problems.