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Old 4th April 2009, 09:35 PM   #1
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Default Preamp with Loudness compensation and Subsonic filter

I am looking to build a source selector / preamp with tone controls and loudness / subsonic filter (with the ability to bypass the tone control/loudness/subsonic) for my Elliott P101 amplifier. After searching the net I couldn't find a schematic that has all the features I need, so the next approach is trying to combine Rod Elliott's P99 (Subsonic filter) and Dave Erickson "PC-Preamp".

In your opinion, are these two schematics up to the job - I mean offering better performance than a LM1036 for example? Or do you have other circuits that perform better?

And if I go by this path, in what order should they be connected after the source selector? (my guess would be that the subsonic filter goes first)... Also, I will use relays to be able to switch out of the circuit the subsonic filter and I would like to have another switch to take out the tone controls/loudness/balance (something like Source Direct... to have the box behave only as a source selector / volume controller); but as the volume control is part of one stage of the preamp, is this doable? Other than using more relays to disconnect the preamp's volume pot (R10) from the circuit and connect it directly across the signal? Thanks.

Elliott P99: http://sound.westhost.com/project99.htm
PC-Preamp: http://www.djerickson.com/pcpreamp/pdf/Pc_preamp.pdf
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Old 7th April 2009, 11:16 AM   #2
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Any ideas?
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Old 7th April 2009, 01:30 PM   #3
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Hi ,

I have also searched for the same for a long time but tone control and loudness seems to be a bad word in the diy circles .
There are numerous amps but scant preamps with tone control .
You can use the elektor Single-Chip Tone Control circuit based on 1036.

thats a good option ,or use the P97 and a seperate rumble filter.

somak
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Old 7th April 2009, 03:27 PM   #4
wg_ski is offline wg_ski  United States
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Quote:
Originally posted by somakmaitra
Hi ,
I have also searched for the same for a long time but tone control and loudness seems to be a bad word in the diy circles .
somak
Just buy your 40% tap volume control pot and hang a .033uf cap from the tap - I won't tell anybody.
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Old 7th April 2009, 03:37 PM   #5
mlloyd1 is offline mlloyd1  United States
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you could also search for the apt holman preamp schematic/manual on this board somewhere. those tone controls had good functionality and (fwiw) were patented.

also, if you can find a schematic for some of the older, high end yamaha "natural sound " series preamps, which had variable loudness controls and (iirc) didn't require the tapped pot.

just keep the lid on the preamp case; i won't tell either ...



mlloyd1
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Old 7th April 2009, 04:37 PM   #6
kaos is offline kaos  United States
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I personally have never heard a loudness control that Iíve liked. They all seem off sounding to me, maybe because they donít follow the Fletcher-Munson curve accurately enough. Maybe because they donít take into account speaker efficiency or listener position, who knows. Information on tone controls shouldnít be that hard to find though. Hereís a link to one site, you may already have found it (I won't tell). Figures 2 and 10 look interesting.

http://headwize.com/projects/showfile.php?file=equal_prj.htm
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Old 7th April 2009, 04:40 PM   #7
mlloyd1 is offline mlloyd1  United States
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i hear you - that is one reason why the yamaha approach was interesting. it was variable from none to full loudness compensation.

mlloyd1

Quote:
Originally posted by kaos
I personally have never heard a loudness control that Iíve liked.
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Old 7th April 2009, 05:16 PM   #8
wg_ski is offline wg_ski  United States
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Default Blame it on the recording engineers

Quote:
Originally posted by kaos
I personally have never heard a loudness control that Iíve liked. They all seem off sounding to me, maybe because they donít follow the Fletcher-Munson curve accurately enough.

Maybe because with modern recordings which have the levels ridiculously high your amp is already clipping when the volume pot is set at the 10:00 position.
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