Passive Pre with remote control for 1 of 3 sources

[Aljaheejus]

My Foreplay is the center of the system.  Happy to adjust volume manually for most listening, sources.  On one input, however, (streaming video sources) I want to add a remote volume control with mute in front of the Foreplay preamp.  I'd like to build a passive preamp with a single, stereo, volume control to attenuate one of the Foreplay's inputs.

What value of the volume potentiometer should I select?  I have read Mr. P. Joppa's input impedance post, and other similar topics, but not being an electrical engineer I only understand enough to be dangerous.    It sounds like a 10Kohm value will be best, as that is below the 33Kohm - ... of the Foreplay's input impedance. 

Suggestions for hardware for a simple passive preamp with remote control.  An Alps RK168 12MG-F20-A103-M0 looks about right from what I know and don't know.

 

[Gerry E.]

Hi:

You didn’t specify a price range but here’s one option:

https://khozmo.com/

Gerry

 

[Paul Birkeland]

If this is a Foreplay III, the input impedance depends on the resistors populating the terminal strips by the selector switch, and I would expect it to be over  50K in most situations.

Can you describe the rest of your system?  Power amps? Speakers? Active subwoofer?

It's quite possible that the best place for a remote attenuator module is between the Foreplay and your amplifiers.

 

[Aljaheejus]

Thanks, Paul, Gerry!  Retrofitting a Khozmo in place of the Sweetest Whispers of my Foreplay could be an option someday, but it's not in the cards at this time.

Here's more detail on my cobbled-together system.  Listening to Klipsch Forte speakers (recapped, Crites drivers), Yamaha Natural Sound M-45 amp (attenuated significantly with panel pots), Foreplay (stock build except for some obligato 2uF caps), Musical Fidelity V-90 DAC is my source for USB, CD (coax), and HDMI splitter streaming sources - the latter of which is optical feed to the DAC, and  the only one I really need remote volume and mute for.

Location between preamp and amp would be handy, but my budget does not afford Khozmo or fancy hifi component at this time.  I am looking for an < $50 parts DIY device, ideally; and being suspect of audio quality at that price point, I thought it'd be safer to put it just on the input to pre from the DAC/HDMI source.

 

[Paul Birkeland]

Location between preamp and amp would be handy, but my budget does not afford Khozmo or fancy hifi component at this time.  I am looking for an < $50 parts DIY device, ideally; and being suspect of audio quality at that price point, I thought it'd be safer to put it just on the input to pre from the DAC/HDMI source.

Using a power amp with 30dB of gain and a relatively high gain preamp together will definitely cause some issues, thank goodness those trim pots are there!

Your power amp has an input impedance of 20K, so it's not exactly well suited to being driven by any kind of passive device.  If the source you want to control has relatively low output impedance, feeding that into a 10K remote level control is probably your best bet, and there are some inexpensive kits available overseas.

 

[Aljaheejus]

Thanks for the information, your time, k n o w l e d g e (mostly over my head) and answer (10K)!  If I understand a few things right, I really need to get my now-old S.E.X kit built for the Forte speakers.

Now I am curious, though, what (tube?) amp, exemplary or type of amp, would be a good fit between the Foreplay and high sensitivity speakers like my Forte II speakers? 

I'm going to ready this post, next:  Topic: Foreplay II excessive gain- amp pairing  to try and figure out in what system would the Foreplay be able to really shine.

 

[Paul Birkeland]

You want to look for an amp with very little gain.  15dB or less is more than enough for what you're up to, and a SEX amp wouldn't be a bad place to start (provided it isn't the Gen 1 monoblocks or the Gen2 still rocking the Speco output transformers).