Sweet Whispers

M

mojo

New member
Hello,

My Foreplay volume controls have developed static when turning them up or down. There is no noise when I set the volume and leave it. I did not build it...John Tucker built it back in 2002 along with my Parabees. I took the Foreplay to a trusted tube stereo repair guy in town and he cleaned the controls. It made no noise for a couple of weeks, and now the static is back.
I've done some reading on the forum, seems my options are to have him take the attenuators apart, clean them better and try to improve the contacts, or buy new controls such as Alps or Goldpoints.
My questions are:
1. Is it worth taking them apart and trying to make them work better?
2. Can I have him build new attenuators exactly like the Sweet Whispers with new parts? Opinions on which resistors and switches would be appreciated.
3. Is it easier/cheaper to buy new ones such as Alps or Goldpoints?

I LOVE the way my system sounds...so whatever I do, I want it to be as good or better than it is now.
Btw...the original TJ 300b tubes still worked after 16 years...they were just really weak, so I bought new tubes (Gold Lions) and it livened things up a bit. Listening to music is an amazing experience again. I love my Bottlehead gear!

Any advice is appreciated.
Sean

 
Hey Paul,
thanks for the quick reply. Any recommendation for easy replacements that won't be a drop in sound quality? Any specific values I should be looking for? Regarding my original post, I'm not just looking for the cheapest solution, I don't mind paying for quality parts.
Thanks again,
Sean
 
They are 15K units, but 10K mono attenuators are going to work just fine.  In the stock configuration, just the ground and input holes would be use on aftermarket attenuators. 
 

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You'll need a small flat file to make some notches in the top panel, but this is still easier than pulling apart the old switches.
 
Natural Sound said:
Mojo, if you want to stick with the stock switch I'm told that that this is an exact replacement.
https://www.digikey.com/product-detail/en/c-k-components/A11203RNZQ/CKN10201-ND/2043157
I would source new resistors rather than try to de-solder and re-use the old ones. You could upgrade to KOA Speer, Vishay/Dale RN55 or RN60 (which are my favorites) among others.

PS: I'm not trying to talk you into anything. I'm just offering you another option.

.
Click to expand...
That is NOT a suitable switch. That one is "non-shorting," meaning that the wiper loses contact with one position before connecting to the next position. This causes clicks and pops with every movement. You need a "shorting" switch.

From the data sheet, that would be model A11203RSZQ. It is NOT available on the DigiKey site.

Switches are getting harder to find, distributors are carrying fewer items, and what there is is costing more. And it often seems to be of lower quality. I suppose there is less demand. I looked around when this thread first appeared, and found only one available-from-stock switch in a couple hours of searching - and they were $180 each, not the $3.95 we paid for the stock switch 20 years ago. It's very frustrating.

I agree with PB's suggestion, to go back to a potentiometer. PEC makes good carbon pots (you want audio taper, also called log taper). They have a carbon puck instead of the usual metal wiper, so operation is smoother, quieter, and probably more long-lasting. There are other quality pots around that cost more and may or may not sound better to you.

The other alternative is to find some ready-made switched attenuators - not cheap. Discrete resistors - I agree that the Vishay/Dale RN series are excellent - are preferred.
 
That post from PB refers to Sweetest Whispers, the revised circuit used in Foreplay III. Sweet Whispers is the old control used in previous versions, which is (I think) what you have.

I was thinking mono pots, assuming you are using one control per channel now and want to keep that.

One of the most common problems with stereo level controls is that they don't track well at low volume settings. That's why Foreplay started out using two mono controls.

I have tried to avoid getting into all the possible different circuits and controls you might use - that would call for a book, not a forum post!
 
Paul Joppa said:
That post from PB refers to Sweetest Whispers, the revised circuit used in Foreplay III. Sweet Whispers is the old control used in previous versions, which is (I think) what you have.

I was thinking mono pots, assuming you are using one control per channel now and want to keep that.

One of the most common problems with stereo level controls is that they don't track well at low volume settings. That's why Foreplay started out using two mono controls.

I have tried to avoid getting into all the possible different circuits and controls you might use - that would call for a book, not a forum post!
Click to expand...

Got it. My experience has only been with the FPIII circuit. I was unaware of the Sweet/Sweetest differentiation. Is the main difference in the FPIII version that the signal AND ground is switched? Or is there something else going on?
 
I can't remember the difference between Sweet Whispers and Sweetest Whispers. 

I remember that the Sweetest Whispers were 15K controls just acting as a shunt element with a variety of fixed series resistors to provide some pre-attenutation. 

Somewhere I have a Sweet Whispers paper manual, I'll have to go digging!
 
Oh, there's a bunch of differences. Yes the original FP switched only the "hot" signal lines to select the source. The level controls had quite a number of variants, especially if you count the ones popular on the Forum that never became Bottlehead kits but were widely used, and the various approaches to reducing the gain which was excessive for some power amplifier/speaker combinations.

Also the chassis was grounded to signal ground at some point; I'm not sure when. We were still learning about grounding, ground loops,  and shielding. Well, honestly, we aren't done learning yet!

The design started with George Wright, then for several years the modifications were done sort of collaboratively with several people including various Forum members. When I re-did the design as FP-III - 2005 maybe? - I changed the operating points of the triodes and introduced the Sweetest Whispers topology - yet another level control. As I recall, I was over at the Schmalle's that weekend and the idea occurred to me during a morning run with Dan. Since then, I did the volume/balance control in Stereomour, and later Paul Birkeland made the BeeQuiet coarse/fine switched attenuator which is currently our best.

I still run the FP-III in my own system.
 
wow...I'm a bit more confused now. That's a lot of info to take in. I definitely want to keep the mono controls, and I don't want to go backwards in regards to sound quality. As I mentioned, I did not build these...I'm not much of a DIY electronics guy, so when the time comes I will need someone to solder everything up. It would be nice if someone from the Bottlehead community could work on it for me. I should mention that when John built these he cut the base of the Foreplay to 1/2 height, so between the carbon PEC potentiometer, ready-made switched attenuators, or attenuators built with new resistors, is there an option that would fit best or one that would definitely not fit? From that which would be the best long term solution with sound close to the Sweet Whispers?

When the time comes, I will order all the parts and hopefully someone here who understands the circuit will solder everything together!

Thanks a ton everybody.
Sean
 
I do lots of refurbishment of our legacy kits, and I can certainly replace the attenuators provided your kit is mostly stock.  While I'm in there, I would replace the power supply capacitors as a precaution. 

When I service these old Foreplay preamps, I will tend to convert them to a stereo potentiometer in one hole and a rotary switch in the other.  The stereo pot works in the conventional manner we are all accustomed to, and the rotary switch is an adjustable pad to provide some preattenuation. 

If you'd like to chat more about these possibilities, I can be reached at pb(at)bottlehead(dot)com.\

-PB
 
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