News: Trouble logging in? Log in from the login page.
September 22, 2019, 08:57:31 AM

Author Topic: Need to Replace Volume Pots  (Read 600 times)

0 Members and 1 Guest are viewing this topic.

Offline arturo7

  • Newbie
  • *
  • Posts: 5
Need to Replace Volume Pots
« on: July 29, 2018, 12:24:35 PM »
I just broke one of the volume pots on my Foreplay III. I took the knobs off the clean the pots and the knob didn't want to go back on. I applied too much pressure and the pot blew up. I guess I should replace both of them while I'm at it.

This may be too broad of a question, but what are my options?

Thanks

Offline Natural Sound

  • Sr. Member
  • ****
  • Posts: 851
Re: Need to Replace Volume Pots
« Reply #1 on: July 29, 2018, 01:15:58 PM »
The FPIII didn't use potentiometers. It used a stepped attenuator called, "sweetest whispers." Unless of course yours was modified.

If you need to build a new one this switch is reported to work.
https://www.digikey.com/product-detail/en/c-k-components/A11203RNZQ/CKN10201-ND/2043157
« Last Edit: July 29, 2018, 01:21:30 PM by Natural Sound »

Offline arturo7

  • Newbie
  • *
  • Posts: 5
Re: Need to Replace Volume Pots
« Reply #2 on: July 29, 2018, 02:12:22 PM »
Thank you, Mr Sound! That looks like a 1:1 replacement.

I think it would be better for me to replace all of the attached components rather than un-solder and re-solder. My assembly manual is long gone. I'm assuming I can download another but I didn't see a link.

 

Offline arturo7

  • Newbie
  • *
  • Posts: 5
Re: Need to Replace Volume Pots
« Reply #3 on: July 29, 2018, 03:10:47 PM »
Cruising around the site, I see the SmashQuiet attenuator upgrade. Is this compatible with the FPIII?

Offline Natural Sound

  • Sr. Member
  • ****
  • Posts: 851
Re: Need to Replace Volume Pots
« Reply #4 on: July 30, 2018, 09:27:33 AM »
No, the SmashQuiet attenuator upgrade is not compatible.

If it were me I'd order replacement resistors along with the switches and not mess with de-soldering the old ones.

Since you don't have the manual for the whispers you have a little work ahead of you. Not to worry though it shouldn't take too long. The best way is to read the resistor bands and figure out the value. I'd then take a resistance measurement with your digital meter to verify your outcome. You may want to have a strong light and a magnifying glass ready since the resistors are pretty small.

Optional - Chances are you installed the recommended 33k padding resistors during construction. These are the resistors soldered to the input selector switch. If you find that your system gets pretty loud just after a few clicks now would be a good time to address that.

According to the manual 33K is the stock value to achieve an overall gain of 10dB. To pad down from the stock 10dB gain use the following guide. (From page 24 of the FPIII manual)

-6dB (80.6K ohms)
-12dB (182K ohms)
-18dB (360K ohms)

http://cdn.wonderfulengineering.com/wp-content/uploads/2014/06/What-is-a-resistor-9.jpg

I hope this helps.

Offline arturo7

  • Newbie
  • *
  • Posts: 5
Re: Need to Replace Volume Pots
« Reply #5 on: August 01, 2018, 01:50:02 PM »
Thank you!

Offline arturo7

  • Newbie
  • *
  • Posts: 5
Re: Need to Replace Volume Pots
« Reply #6 on: August 04, 2018, 07:00:50 AM »
Holy garbanzos!

I found the Foreplay manual, complete with SW insert.

Strike up the band!