What Foreplay version / mods do I have?

[Evans64]

 Just purchased a Foreplay that has some mods done to it, which ones I am not exactly sure, hopefully the images will give a clue. Can anyone let me know about the attenuators for left and right channel and their relative positions?

[Paul Joppa]

Looks like a Foreplay 2, with Anticipation current sources, upgraded output capacitors (Auricaps), and Sweet Whispers 12-step switched attenuators, which appear to be wired in shunt mode.

[Evans64]

 Thank you for your thoughts - I noticed that the volume attenuators are very noisy, a good amount of hum, popping and worse if I go to select the next level it will usually be at a much high volume level. I have heard these are good but also noticed a pair of Alpha brand ' 4B4 ' 100K potentiometers that were included. Perhaps after attempting to clean the Sweet Whispers with Deoxit and there is an improvement all is well but perhaps using the Alpha pots might be alright?

  Have no idea if they might alter the sonics in some way but as it stands the pre amp is unusable, can barely touch the knobs but playing well enough 2 steps from off position. A bit scary in a way as one does not want to see their speakers damaged!


 I have a friend who does electronics repair that could give it a look over and test.

[Evans64]

 I wonder if any of the parts that it came with have any use?

[Paul Joppa]

The switched attenuators were an upgrade kit; they replaced the 100K Alpha pots. The main advantage was easier to match the channel volume levels. The shunt-mode wiring makes for loud switching noise, especially if the switch is worn or dirty. The first step is big (12dB IIRC), next step 6dB; the rest are 3dB.

The original Foreplay had a relatively high gain. Hair-trigger volume control was a common symptom, and there were various mods to bring it into line with the rest of a system.

You mentioned hum - there was a popular mod, which is to connect the chassis to the signal ground, and often reduced hum. It just soldered two adjacent terminals to each other. I can't see if that has been done - it's on the terminal strap behind the tube sockets.

The circuit boards are C4S current sources, a more recent incarnation than the original boards already in the preamp, but out of production currently.

That glob of electrolytic caps looks like a power supply from a Seduction phono preamp. Some people retrofitted the seduction power transformer and supply into their Foreplays because it was quieter. (I don't see a Seduction transformer, though.

[Evans64]

  Seems the image files are a bit too large, will see if I can reduce them. The transformer is a smaller all black unit.  I will look and see if there is that suggested grounding.



  All I can see is  a ground wire from the power cord junction block, another two from the transformer to the on / off switch and to the main fuse and those coming from the two Auricaps. Also a ground wire between the two 12AU7 tube sockets.

[Paul Birkeland]

The typical remedy for the noisy SW level controls was a pair of 10K mono Goldpoint attenuators.  One could also simply add a stereo level control and a hole plug for one side of the chassis as well.

[Paul Joppa]

The power transformer has been panted black, making it hard to photograph. A closer, better illuminated look at it would help, but I think the colors of the wires suggest it's the stock unit.

The black ground wire from the terminal block appears to go to some place on the the terminal strip under the central yellow Auricap. If it goes to the central terminal of that strip, which is grounded to the chassis by its mounting bolt, then you have a good safety ground. That terminal is number 13; if it is also connected to the adjacent terminal 14 then you have the grounding mod.

I can't see the selector and level switches clearly enough to tell how they are wired. I don't recognize that green rectangular component near the lower left. Dd you get the manuals with the kit? I ask because they are hard to come by - the digital version is in an obsolete format, and I am not aware of any Sweet Whispers manual - I don't even have a paper copy.

[Evans64]

  There are a few manuals - Foreplay construction guide ( Rev 2.0 ); Foreplay III manual; Extended Foreplay manual; Anticipation installation guide; Sweetest Whisperers assembly instructions. ( 2 pages ).

 I noticed that the nut that secures the input RCAs on one pair are loose, the ones closest to the 12AU7 tubes so will be tightening them down carefully of course. A few of the resistors that are soldered to the attenuators look like they were subjected to enough heat to discolour, tight fit I realize and they are quite small as well.


 After Deoxit is used on the switches I will turn on the Foreplay again and hopefully it will be better. If worse comes to worse I should entertain new volume controls.

 The green component is soldered with some resistors going between one of the tube sockets and the volume attenuator on that side. I have very little experience with circuits but slowly grasping some of it, my friend can certainly go through it and test overall performance and parameters and hopefully trace where the hum is originating. The 12AU7 tubes are Raytheons.

[Evans64]

 i can se that one ground wire comes from the terminal block for the power cord and goes directly to the terminal strip along the tube sockets and is soldered to a lug directly above the mounting point . Nothing else beyond that other than a few shorter ground wires going from that terminal strip to points on the tubes and volume switch.


 I can try and get a close up of those areas. I do not see that extra chassis grounding mentioned earlier.

[Evans64]

 The Deoxit appears to have helped, forgot to check for humming at idle, I do not think there was much after I tightened the grounding nuts on some of the RCA inputs. The right volume switch is definitely not 100%. I moved both of them about 5 notches from off and then adjusted the gain on the Rotel power amp which fortunately has them.


 Perhaps further cleaning might do the trick, at l least the selector switch and left attenuator are good.