Bottlehead Forum

Bottlehead Kits => Legacy Kit Products => Foreplay III => Topic started by: JFugazzi on October 29, 2009, 03:34:54 PM

Title: Using a Stereo Volume Control on the Foreplay III
Post by: JFugazzi on October 29, 2009, 03:34:54 PM

Hi everyone.

I have a Foreplay III on order and i'm thinking about building it with a Goldpoint Mini-V stereo volume control
instead of the supplied 2 volume control setup. If anyone has done this can you let me know if the standard
Mini-V control will work with the Foreplay or do I need special resistors installed? Also what size knobs should
I get? Its hard to tell from the website pictures.

Thanks

Joe Fugazzi

Title: Re: Using a Stereo Volume Control on the Foreplay III
Post by: Paul Joppa on October 29, 2009, 06:40:36 PM

I still recommend the Foreplay method of connecting the volume control, which is not standard but should be fairly clear from the circuit diagram and the pictures in the manual.

The Goldpoints need a modification of the mounting holes - Goldpoint supplies good information on this. A reamer can be had fairly cheaply that will do the main job. You can put the stereo control in either hole; you'll probably want to plug the other hole eventually. There is no balance control unless you use the empty hole for that; we don't at this point have a recommended way to do this but there are many ideas on the internet.

Title: Re: Using a Stereo Volume Control on the Foreplay III
Post by: Paul Birkeland on October 29, 2009, 09:22:39 PM

Any of the knobs should work just fine, I would say go larger to be on the safe side, as the Goldpoints don't require the offset hole that the stock switches do. 

You can wire the switch in as is drawn out in the Foreplay III schematic, or you can wire them in as a standard attenuator (the pads on the attenuator are labeled for this). 

I find that with the additional steps of the Goldpoints, I can get away with just one pair of padding resistors for all three inputs.  Therefore, when I build a Foreplay III with Goldpoints, I will wire each channel from the RCA jacks right into the input selector switch, then place the padding resistors between the selector switch and the input of the attenuators. 

Title: Re: Using a Stereo Volume Control on the Foreplay III
Post by: debk on May 07, 2010, 01:14:41 PM

Quote from: Paul Joppa on October 29, 2009, 06:40:36 PM

I still recommend the Foreplay method of connecting the volume control, which is not standard but should be fairly clear from the circuit diagram and the pictures in the manual.

The Goldpoints need a modification of the mounting holes - Goldpoint supplies good information on this. A reamer can be had fairly cheaply that will do the main job. You can put the stereo control in either hole; you'll probably want to plug the other hole eventually. There is no balance control unless you use the empty hole for that; we don't at this point have a recommended way to do this but there are many ideas on the internet.

If I understand the circuit diagram the way you have the attenuator hooked up is the input and output(wiper) is reversed from how the attenuator would normally be hooked up

Title: Re: Using a Stereo Volume Control on the Foreplay III
Post by: Grainger49 on May 07, 2010, 01:27:53 PM

Yes, the "top" of the pot is usually the input but in the case of the FP III it is the output.  The wiper is usually the output but here it is the input.  Ground is still ground, of course.

Part of this scheme includes the series resistor.  If another volume device is substituted and the stock configuration is kept, the series resistor must stay also.  Otherwise with no series resistor the source selected is shorted to ground at zero volume.

Title: Re: Using a Stereo Volume Control on the Foreplay III
Post by: debk on May 07, 2010, 02:14:00 PM

The series resistor is the 33K connected from the source to the selector switch?

I have two Goldpoint 15K stepped attenuators that I have built.  To subsitute them I would just attach the output of the selector switch to the output(wiper) on the goldpoint, and the input on the goldpoint would go to the proper terminal on the terminal strip.  The ground would be unchanged and I would change nothing else?

Thanks

Debra

Title: Re: Using a Stereo Volume Control on the Foreplay III
Post by: Grainger49 on May 07, 2010, 03:31:04 PM

Yes to the series resistor.  And yes to the wiring you describe.

Title: Re: Using a Stereo Volume Control on the Foreplay III
Post by: debk on May 07, 2010, 03:35:51 PM

Thank you. I appreciate the help

Debra

Title: Re: Using a Stereo Volume Control on the Foreplay III
Post by: porcupunctis on August 11, 2011, 11:41:17 AM

New post in really old thread but:

Thanks to Deb, Grainger, and Paul J. for all the great info on installing the goldpoints.  There is no telling how many people this has helped.

I even took up Deb's suggestion of testing it out with Supertramp's "Crime of the Century" which I'm enjoying very well right now.  You can't go wrong with one of the top 100 classic Prog albums of all time.

Thanks again, you totally saved me from hooking this up in a completely fubar way.