The remote control paratactic volume control

[amplifierguru]

Hi audio-gd,

Can you scale the R's down so Rout = 1K . 10 times lower and what would be Rin loading for previous stage. High Z is more noisy also a good reason for low Z.

 

[HFGuy]

Thermal Noise (also called Johnson Noise)

en = sqrt{4kTRdelta(f)}

Reduce the bandwidth or Resistance

 

[amplifierguru]

Very good, HF Guy!
that little k is Boltzmann's constant = 1.38 x 10to the power -23 juoles/deg kelvin. Not something I have instant recall of always.

I always remember it as 4nV/ sqrt Hz for a 1K resistor and proportional to sqrt R for scaling.

It helps being a physicist.

 

[audio-gd]

Change the resistance can change the impedance, but a bit thick small will weightily load to forward stage, although it can lessen the noise and more.

 

[amplifierguru]

Audio-gd

How weighty - 10K loading on CD or line amp is OK.

 

[mastertech]

what parasitic?
what is parasitic volume control?
all i see is a logarithmic attenuatorl
please enlighten me

 

[audio-gd]

10K is ok, but if less than 10K, for example :1K, it's weightiness load to CD or some buffer.

 

[amplifierguru]

Just to clarify, you can make it so it is -

10K load on preamp and 1K source to power amp, yes?

 

[audio-gd]

No, I only can make as a manual volume controler

 

[Artmaster]

volume controler... what for?
could you change volume level in the concert hall?
I'm not think so.
I never do any volume control in my amplifier. I've set it up during instalation.
I have not problem about different room reaction by different sound precure

and I have clean fron panel as well
http://www.artmaydan.org.ua/hi-end/amp_s.jpg
http://www.artmaydan.org.ua/amp.html

 

[ilimzn]

Is it just me or does it look far too complicated for what it needs to do? It's not too diufficult to make an attenuator that has 2^N steps (N being the number of relay contacts), and has any dB per step value you want, using 2*N + 1 resistors, that also has constant output and input resistance regardless of the setting, and can be driven by a binary combination to address the attenuation needed, dirtectly?

 

[Gordy]

OK, let's revive this post...

Is it just me or does it look far too complicated for what it needs to do? It's not too diufficult to make an attenuator that has 2^N steps (N being the number of relay contacts), and has any dB per step value you want, using 2*N + 1 resistors, that also has constant output and input resistance regardless of the setting, and can be driven by a binary combination to address the attenuation needed, dirtectly?

Can someone (ilimzn perhaps) please guide me to a circuit for this " 2^N steps (N being the number of relay contacts), and has any dB per step value you want, using 2*N + 1 resistors, that also has constant output and input resistance regardless of the setting, and can be driven by a binary combination " type of volume control / attenuator.

I would appreciate the circuit for the control system as well as the attenuator.

Many thanks.

 

[Arlo]

it seems a series type volume control.

how about to build a shunt type?
but shunt type volume control needs twice of relay and resistor.
i have a todo plan to build a shunt type volumen control using
bit map control. anyone have interesting?

 

[CeramicMan]

Create a reed switch controller using a flash ADC with any analog voltage sensing on the input... even an ordinary volume pot?