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Old 2nd November 2004, 06:15 PM   #1
lugi_sp is offline lugi_sp  Italy
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Default quad 44 preamp

hi, im to mend a quad 44 preamp. i need the circuit diagram and layout, if possible,of this boards:
12784-2 tone control board with 5 tl072
2090-1 input selector

thanks

fred
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Old 2nd November 2004, 08:43 PM   #2
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A quick search here on diyAudio gave this link:
http://iquebec.ifrance.com/quadfranc...schemas44.html
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Free Schematic and Service Manual downloads www.audio-circuit.dk, Company: www.dupont-audio.com, Joint venture: www.DupontMantra.com
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Old 2nd November 2004, 10:20 PM   #3
lugi_sp is offline lugi_sp  Italy
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Default quad 44

Sorry, tone control board with part number 12784-2 isn't present on site www.iqbec...ect.
The tone board persent is a old version.
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Old 1st February 2013, 09:33 PM   #4
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Default Various Questions to the kind of Tone Control from Modell 44

I have various questions to follow preamplifier:
Quad
1) the tone control that works here is an is an alternative to James-Baxandall's passive tone-Control network.
Which colloquial term exist therefore and how I calculate the values (calculation steps) ?
2) Who can tell me a link for curvature diagrams and schematic or can upload the graphs and schematic?

Thank you in advance for the appropriate advices.
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Old 3rd February 2013, 12:39 AM   #5
Zigis is offline Zigis  Latvia
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tiefbassuebertr , see in your link Quad34 preamp, service manual, there is very detailed description, how tilt and bass control work.
Simpler and better variation of tilt you can see in this article:
Designing A Pocket Equalizer For Headphone Listening | HeadWize
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Old 3rd February 2013, 07:24 PM   #6
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DADA Electronics Europe used to have QUAD manuals available for download, but now you have to login for downloads. You might want to contact them and ask about obtaining the schematic.

Ray
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Old 3rd February 2013, 09:03 PM   #7
Zigis is offline Zigis  Latvia
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Here is service manual:
http://www.meridian-audio.info/publi...%5b1582%5d.pdf

inside are schematic, tone control description, everything.
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Old 4th February 2013, 09:12 AM   #8
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Quote:
Originally Posted by Zigis View Post
tiefbassuebertr , see in your link Quad34 preamp, service manual, there is very detailed description, how tilt and bass control work.
Simpler and better variation of tilt you can see in this article:
Designing A Pocket Equalizer For Headphone Listening | HeadWize
Quote:
Originally Posted by Zigis View Post
Here is service manual:
http://www.meridian-audio.info/publi...%5b1582%5d.pdf

inside are schematic, tone control description, everything.
Thank you very much - this was that I am looking for.
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Old 4th February 2013, 06:37 PM   #9
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Quote:
Originally Posted by tiefbassuebertr View Post
I have various questions to follow preamplifier:
Quad
1) the tone control that works here is an is an alternative to James-Baxandall's passive tone-Control network.
Which colloquial term exist therefore and how I calculate the values (calculation steps) ?
According the URL
Implement an audio-frequency tilt-equalizer filter | EDN
the colloquial term is "Tilt-Equalizer" or “tilt” audio-tone control
The tilt control tilts the frequency content of the audio signal by simultaneously boosting the treble and cutting the bass frequencies, or vice versa. Only one knob is needed to tilt the frequency response around a pivot frequency, FP.
How I can reduce the elements, if I want to realize only the possibility of boosting the treble and cutting the bass frequencies from the flat-position (the opposite case I don't need) ??
In this case I am looking for calculating by a portal like that for active crossover networks - go to
http://www.beis.de/Elektronik/Filter...eLPFilter.html
Maybe one of the members know this.

Additional I want to shift the lower cut-off frequency (center- resp. pivot frequency in the genuine topology to adjust in both directions).

Thank you for advices.
Attached Images
File Type: png tilt tone control.png (32.7 KB, 194 views)

Last edited by tiefbassuebertr; 4th February 2013 at 06:54 PM.
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Old 5th December 2013, 09:59 AM   #10
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[QUOTE=tiefbassuebertr;3355851]
How I can reduce the elements, if I want to realize only the possibility of boosting the treble and cutting the bass frequencies from the flat-position (the opposite case I don't need) ??
......
Additional I want to shift the lower cut-off frequency (center- resp. pivot frequency in the genuine topology to adjust in both directions).

Hi,
to have only bass cut and hi boost add an appropriate resistor at the right of the potenziometer, the sum of the pot. value + the new resistor must bee like the old value of the pot.;
to shift the pivot frequency see my EDN article:

Implement an audio-frequency tilt-equalizer filter | EDN

With that formulas you don't need spice try-and- errors loops. Asymmetric responces are possible !
Need more? Francesco Balena
ps. if you want some actual implementatio
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