What Impedance of Attenuator does a Foreplay II Require?

[williaty]

I have a Foreplay II that has the Sweet Whispers kit in it. However, the 30dB range just isn't cutting it to go from listening to music while my wife sleeps to listening to music while everyone's awake and the source is a weak phono pre. I'm going to replace the dual mono steppers with a single stereo stepper. What impedance of stepper do I need to be shopping for?

Thanks,
Ty

 

[galyons]

I have 50K mono's in one and  100K mono's in another. Both work well without issue.

Cheers,
Geary

 

[galyons]

BTW, you can also increase the attenuation of the sweet whispers to solve the problem, as well.  There is substantial discussion on the old AA/BH archive. 
http://www.audioasylum.com/forums/bottlehead/bbs.html
Search on poster voltsecond.  The sweet whispers are really pretty nice sounding, in comparison to alternatives.

Cheers,
Geary

 

[williaty]

I'd have to desolder all the existing resistors because I don't want to just increase the attenuation, I need to increase the *range* of attenuation. I'm already using both full up and full down and they're not far enough apart.

 

[Grainger49]

You may need a "Day/Night" switch.  The FP III uses a series resistor before the stock SW set up.  The stock volume control was much lower than the standard 100k Ohm for most other Bottlehead equipment.  There were 3 other resistors included in the kit for different amounts of attenuation.

What you can do is to buy a lower impedance, 30k, 25k, stepped attenuator and use a DPDT toggle switch to select the daytime series resistor or the night time series resistor.  The night time would give you finer resolution but a lower volume.

 

[Paul Birkeland]

I'd have to desolder all the existing resistors because I don't want to just increase the attenuation, I need to increase the *range* of attenuation. I'm already using both full up and full down and they're not far enough apart.

Buy a DPDT switch and a pair of resistors that are 10X the value of the current resistors between the selector switch and each sweetest whisper.

Wire the center pair of lugs from the DPDT switch out to each Sweetest Whisper attenuator.

One pair of lugs will take the original resistors from the selector switch, the other pair of lugs will take the 10X value resistors that are also tied to the selector switch. 

This will give you tremendous pad if you need it.  For example, the SW is a 15K attenuator, and if we assume you have 30K series resistors installed, you have:

Stock padding - 9.5dB
10x padding - 26dB

This will give you nearly no overlap of switch positions.  (The quietest step on the -9.5dB setting will be roughly the loudest on the -26dB setting)

-PB

 

[williaty]

I've been looking at ebay and there's some cheap mono stepped attenuators out there that are 24 steps over 75dB (~3.1dB/step). The SWs I have in there now are 3dB/step, according to a VERY old post by Doc. So it looks to me like I could more than double my range (similar to adding a day/night switch) with roughly the same degree of control resolution by buying a pair of those cheap eBay steppers.

Is there any reason to prefer the 50k vs 100k impedance version?

 

[Paul Birkeland]

Yes, a 50 or 100k set of controls like that will work.

At one point I had such a setup, and I found it tough to keep track of the steps between right and left channels, so I'd suggest a stereo switch, and perhaps a rotary switch in the empty hole for some extra padding if necessary.

 

[williaty]

Hmm, I had planed to do as I do now and just keep the lines on the knobs pointing in the same direction, but I can see that with half the step size, it'll be less obvious if they're misaligned. I suppose I could just replace one of the SWs with the stereo control and then leave the other one there for appearance's sake.