Experimenting with the FPIII.

[Natural Sound]

Several years ago I picked up a partially assembled Foreplay III on eBay, dirt cheap. The sale included the Extended Foreplay upgrade kit, un-assembled. My intent was to put together a 6SN7 FPIII pre-amp. The implementation of "hole shrinkers" back in the day would facilitate this socket and wiring modification quite easily. Well, life got busy and and the pre-amp wound up sitting in a box in my closet for at least a decade. Probably a bit longer, I'm not sure. Like I said, life got busy.

This amp was pretty beat up both cosmetically and functionally. Which was part of the reason why I got it so cheap. With a couple of replacement parts from Mouser and a few hours of my now retired time, I'm happy to report that the old girl is singing away beautifully in its stock form. 0D3 regulator and all. The sale came with Russian made Electro Harmonix 12AU7's so I decided to use those in my initial testing. I'm very pleased with the sound so far.

In the mean time I've acquired several 6CG7 pairs over the years. So my journey is taking a bit of a detour. In the next day or so I'll make the necessary filament changes necessary to run the 6CG7's. After some careful listening I'll decide if I want to go further with the 6SN7's.

 

[Natural Sound]

Hey, P.B. Do you see any problems with pairing a FPIII with a SEX4? Just thinking ahead.

 

[Paul Birkeland]

That would certainly work well, especially with the SEX 4 running in the lower gain switch position.

 

[Paul Joppa]

Not PB, but the only problem I can see is the FP-III in stock form has too much gain, which it has with any amp. I'm running my FP-III into low-gain monoblocks (2+ volts sensitivity) and still use a 12dB inline attenuator. :^)

 

[Natural Sound]

Not PB, but the only problem I can see is the FP-III in stock form has too much gain, which it has with any amp. I'm running my FP-III into low-gain monoblocks (2+ volts sensitivity) and still use a 12dB inline attenuator. :^)

Thanks PJ. Even with the maximum input padding resistor value?

That's one of the things I like about the FPIII. I have two of them by the way. I can use my old school Seduction and a modern DAC and not have a huge delta in volume if I select a suitable padding resistor for each input.

Would your monoblocks happen to be Paramour II? One of my systems is a FPIII Into 45 modified Paramour II monoblocks. I find the gain to be high but not excessive.

 

[Paul Joppa]

Why yes! Mt amp is sort of a Paramour II, with 6J5 driver. PB built it for me - these days my hands are too shaky to solder well. Wired to accept a 6N7 or 6P5 (octal 76) and adjustable bias.

 

[Natural Sound]

I understand, Paul. My hands are a bit shaky these days as well. As long as it's nothing too terribly small like surface mount components I manage OK, for now anyway. A little molten wire insulation not withstanding.

Anyway, I'm still going to consider the FPIII / SEX4 combo. If it doesn't work out I'll grab a Moreplay or maybe even play around with a passive pre.

From my manual. A stock padding resistor for the FPIII is 33K for a target of 10 dB of gain.
-6dB ( 80.6K ohms)
-12dB (182K ohms)
-18dB (360K ohms)

I have some nice Vishay Dale RN55 resistors in those values to experiment with.

Thanks again PJ, PB, and all the great folks at Bottlehead. Your input is always greatly appreciated.

This is fun.