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Old 17th July 2002, 03:43 PM   #21
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Default Re: It uses stepped switches

Quote:
Originally posted by gromanswe
CMOS 40193 up/down counter is remotely controlled
CMOS 4051 8-channel analog multiplexer
resistor divider
1 resistor is in series with incoming signal
where only the 8 resistors are switched to GND
the CMOS FETS works best around GND
this is repeated
twice with a buffer OP in between
to get 8x8=64 steps -1dB/step
Hmm yes that could work. Are you using R/2R ladder networks? What is the value of your series resistor? What is the ratio of your series resistor to the lowest value switched resistor?

Jan Didden
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Old 17th July 2002, 03:49 PM   #22
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Default Re: About Attenuating, Volume Control.

Quote:
Originally posted by gromanswe
When using some meters of Loudspeaker cable,
you get one problem. Transfering high currents
at high speeds.
When using bi-/tri-amping with monoblock mounted
next to woofers, you get another problem.
Tranfering the signal attenuated of Volume control
in centerplaced Preamp, to the Endstage.
Hi,

I am interested in this tradeoff, so I started a new thread about it (long cables...) in this forum.

Cheers! Dan
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Old 17th July 2002, 03:56 PM   #23
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I think that remotely controlled volume control module, right at the input of the amplifier would be the best product ever invented for audio. Lets say you are using tri-amping and you have 6 monoblocks amps. The module would be quite small (maybe the size of a computer mouse or smaller ) and it mounts directly to the input jack of the amp, the interconnect cable is connected then to the module. Then you have a remotely controlled central control console which through the remote, communicates with the modules and sets different volume levels and remembers individual adjustments as well. If you take care of source switching somwhere else you have the best passive preamp ever done. I was playing with that idea for last 10 years, somehow never realised it, maybe because I'm not a microcontroller guy.
I've also never seen it implemented. I'm glad someone else is talking about it too.
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Old 17th July 2002, 05:01 PM   #24
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Default Janneman

No, 4051 only closes 1 of 8 Jfets-switch.
So only 1 resistor at the time is connected to GND.
Yes, the lowest resistor is the crushial point
when using JFETS with R-on in the magnitude 50 ohms.

To achieve a result satisfactory to your
acceptance of evnetually distortion
you have to calculate how big is R-on
variations in relation to R1+R2+Ron.

A way around that, for ultimate solution is using
DRY reed relays to switch.

This is my favorite
DSS41A05= needs some 8mA to switch
http://www.alliedelec.com/catalog/ca...s/2002/712.pdf
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Old 17th July 2002, 05:05 PM   #25
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Default Janneman

No, 4051 only closes 1 of 8 Jfets-switch.
So only 1 resistor at the time is connected to GND.
Making a conventional 2-resistor divider.
Yes, the lowest resistor is the crushial point
when using JFETS with R-on in the magnitude 50 ohms.

To achieve a result satisfactory to your
acceptance of distortion,
you have to calculate how big is R-on
variations in relation to R1+R2+Ron.

A way around that, for better solution is using
Dry Reed Relays to switch.

This is my favourite
DSS41A05= needs some 8mA to switch
http://www.alliedelec.com/catalog/ca...s/2002/712.pdf
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Old 17th July 2002, 05:24 PM   #26
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Default And this is etc

Gromanswe,

So I probably misunderstood you, I thought you had it working rather than just as an idea. I was interested in your particular choices.

As to the relays, I have posted earlier my preference for a particular type (Pickering) along with the arguments why I have this preference.

Cheers, Jan Didden
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Old 17th July 2002, 06:00 PM   #27
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Default janneman

I have it working.
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Old 17th July 2002, 08:55 PM   #28
Variac is offline Variac  United States
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Wow - the best product ever invented for audio!



I guess you need to post a schematic soon.
Of course you still have the problem of the poor little low level signal from the source having to travel to the various locations.
Unless you can split up a cd player!
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Old 17th July 2002, 08:59 PM   #29
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Default Variac

I do not claim this to "the best product" for you.
This is what I built over 2 years ago.
A friend who knows how to use CMOS logic helped me
with that part.
It is the best product I have ever built.
That I can claim.
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Old 17th July 2002, 09:13 PM   #30
Variac is offline Variac  United States
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Actually, I was serious- I agree with HPotter- this is pretty cool!
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