Mr. Lin's Foreplay III and ongoing modifications...

[Mr. Lin]

I purchased the FP III kit in 2006, and for a variety of reasons I won't get into here, I didn't get around to building it until about a month ago.  Originally I only got the FP III to use with the Paramour IIs (which I've just finished but not yet fired up), and I have to say this thing performs well beyond what I was anticipating, I'm very happy with it.  It's currently being used in a headphone setup, between a Naim CD player and Pro-Ject Head Box SE headphone amp, with Grado 325i headphones.  

These first two pictures are just so you can see the type of finish I chose for the FP base.  Nothing special.  I plan to paint the bases for the Paramours.  The second picture shows the Sylvania OD3 tube I replaced the Ratheon with, since I can't stand that brown plastic case around the tube.  I now have Herbie's tube dampers on all three tubes, although you only see them on the 12AU7 tubes in the second picture here.  





Before I get into the modifications I'll just note that I use a Weller WD1 soldering station, and love it.  I also now refuse to use any kind of solder other than Cardas Quadeutectic.

I changed out parts in three different areas after about four or five days of listening to the stock FP III.  First, I replaced the stock blue film resistors across the outputs with Takman carbon film resistors - I know, a mortal sin, and if that sends chills up your spine you might not want to read further





To continue on this path of heresy, I installed two Kiwame carbon film resistors in the following places, from the coupling caps to ground (they're the green ones):





At this point I'll note I did not perceive any increase in noise whatsoever, despite the warnings that carbon film resistors are notoriously noisy.  In fact, the FP III surprised me with its silence as well as its excellent performance.  I could swear the Kiwame resistors resulted in a distinctly warmer sound, especially in the lower midrange.  But it's impossible to know for sure given the time that elapsed between hearing the stock resistors and installing, then listening to, the new Kiwame resistors.

Next I replaced the .1uf cap across the OD3 tube with a modern production Sprague "Orange Drop" .1uf cap I had on hand from an older project.  This was a bit of a hassle as the leads on these caps are very large gauge and hard to work with in tight spaces.  This picture shows the whole thing at that point, I didn't take any closeup shots of the Sprague cap.  Whether or not this new cap made any difference in sound quality, I can't tell you:



Next up:  I like to attend to the small things, irrelevant though they may ultimately be - one never knows.  Therefore I replaced the four carbon comp. resistors across the 12AU7 sockets with Riken carbon comp. models, which have gold-plated copper leads.  If nothing else, they sure look cool!





Now we'll take a break so I can go re-size the newest, and arguably most interesting and significant, pictures of the bunch, which will include upgraded signal path caps.


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[Mr. Lin]

Here you can see I've replaced two of the padding resistors with 18k ohm Takman carbon film versions.  Again, despite the warnings about potential noise, I hear none using these.  I prefer the lower resistance so I can turn up the gain on the FP III and keep the volume on the Pro-Ject headphone amp low.  Sounds wonderful. 

I intend to replace a different input pair with some tantalum resistors in the near future. 






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[porcupunctis]

Very nice!  Those tube dampers are a bit unusual.  Did you make them?

I just finished an FPIII myself and I hope that you are enjoying yours as much as I love mine.  I thought I would never get through the build on the input section.  If something ever happened to mine, I think I would buy two more just to be safe.

[Mr. Lin]

And now on to the really good stuff - but first, one more minor alteration:  When I ordered all these boutique resistors I threw in a Jupiter "Vintage Tone" aluminum foil and mylar .1uf cap for the OD3 tube, just because it was inexpensive and I thought it would be fun to play around with.  Normally I'd never go for something labeled "vintage tone," since that's exactly the opposite of the sonic presentation I prefer, but I did it anyway.  Don't know if there was any difference between the Jupiter and the Sprague:



I struggled with the choice between the lauded Obbligato film caps and Jantzen, the latter a Danish brand I've successfully used in a speaker crossover modification.  Having been impressed with the quality of the Jantzen for the price, and considering it was mere dollars more than the same value Obbligato, I opted for the Jantzen "Superior Z-cap," which has 18 awg solid copper leads and a claimed tolerance of + or - 2%.  According to the manufacturer: "These caps are constructed of a specially wound metallized polypropylene to minimize inner vibration."  They offer a silver version, but apparently the only difference is that the leads are solid silver instead of copper, so I stuck with the less expensive copper version.  

This was an easy installation, of course, although they're much larger than the stock film caps (pretty much inevitable with boutique caps it seems).  I have a roll of rather expensive Teflon tape with a silicone adhesive that I normally use when making cables, and I applied a piece of this tape to each cap to separate it from nearby conductive parts and components.  I figure that theoretically this would add additional damping to the capacitor cases.  The Teflon tape is visible in the third and fourth pictures below:









As of right now, the addition of these Jantzen capacitors has yielded the biggest and best improvement in the sound I get from the FP III.  I touched upon this in a thread in the FP III forum the night I installed them - basically it comes down to more of everything that's desirable, and in summary, resolution is significantly enhanced.  Everything sounds much clearer, and more details of the music are now audible.  I certainly recommend these if anyone is looking for a good cap for this place in their FP III.  

I am still curious about those Obbligatos.  I know they're reputable, and Bottlehead forum member Grainger has mentioned more than once how happy he is with them.  Perhaps I'll try those out with my Paramours, down the road.


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[Mr. Lin]

Very nice!  Those tube dampers are a bit unusual.  Did you make them?

I just finished an FPIII myself and I hope that you are enjoying yours as much as I love mine.  I thought I would never get through the build on the input section.  If something ever happened to mine, I think I would buy two more just to be safe.

Thank you!  The tube dampers are made by Herbie's Audio Lab.  He makes all kinds of damping stuff for hi-fi audio, most famously the tube dampers, and his "Way Cool" turntable mat, which I also use.  They're not cheap, but then again, compared to other alternatives, they're a good deal.  I originally bought the dampers I'm now using on the FP for my Wright 200C tube phono preamp.

Yes I really am enjoying my FP III, more than I thought I would.  I know some parts of the build were a bit tedious, the Paramours are much easier by comparison.  One of my least favorite parts was those rectifier diodes in the power supply, with their massive leads that just didn't want to bend!

[Mr. Lin]

And finally, just two more things.  Before I get to those, I'll just note that all the interconnects I use are designed and built by me, something I started doing years ago after trying all manner of esoteric boutique after-market interconnects by the usual suspects.  However, I still use "brand name" power cords.  

It goes like this from wall to FP III:
Oyaide SWO-XXX outlet (yes, an after-market wall outlet )
A Shunyata Diamondback power cord goes from wall outlet to a PS Audio "Juice Bar II" outlet center, which has no surge protection, filtering, etc - just copper buss bars from outlet to outlet.  
A Cardas Golden (not Reference, the one just below it) power cord, which, based on listening tests, seems to be the best I have.
For the source I use either another Shunyata Diamondback, or a Grover Huffman power cable (which utilizes copper and silver ribbons).

I have a great selection of NOS 12AU7 tubes to choose from, almost all from Upscale Audio.  So far I prefer the 1965 Radiotechnique 12AU7, originally made for the French military signal corps.  This one has the same open and bright (in a good way) top-end it's advertised to by Upscale, and is strong all around.  The infamous RCA "clear tops" also work quite well, as do the NOS Siemens Rohre tubes, the latter also from Upscale.  

Ok - back to the last couple minor things I've changed.  First, as much as I love the way those Kiwame resistors look (the green ones seen above), I decided to replace them with a pair of Shinkoh tantalum resistors.  That would be the purple-ish one toward the right of the other resistors in this picture:





Also, I realized a HiFi Tuning Silver Star fuse I have in another headphone amp is the correct value for the FP III, so I popped that in a few nights ago. As with a CD player in the past, the fuse seems to (inexplicably) result in a bigger, more open sound.  I will note these Silver Star fuses didn't seem to produce an audible change in another integrated amp I've tried them in before, so I guess I got lucky with the FP.  I also applied some Mapleshade Audio "Silclear" contact enhancer to the fuse caps.  Silclear is basically a food-grade grease with microscopic silver platelets in it.  I also apply it to all tube pins in my system.  Additionally, I put Cardas Myrtlewood blocks under the FP, and Cardas RCA caps on unused RCA sockets to (hopefully) reduce noise.  Yes, I naively spent a small fortune on the Cardas RCA caps, not knowing at the time that you can buy the same things by a "no-name" brand for a small fraction of the price.  Live and learn.



And finally, I'll wrap this up with a shot of the pleasantly warm glow of the FP III as it currently looks in the dark.  Thanks for reading!




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[Paul Joppa]

Carbon composition resistors are the ones that are noisy, and that's mostly just when they have DC current going through them. Their other disadvantage is they are prone to drift in value with age. Carbon film is considered much more stable, and only slightly at risk of producing noise with DC current. Since all of your replacements have been in places with no DC current, they are just fine. The grid stoppers (the four 220 ohm ones) are in a circuit position where drift in value is not important, even a 50% change in resistance will have no discernible effect. And of course, all these problems with resistors are much less if the resistor is well made.

The resistors with DC current are the four 22.1K load resistors. The best replacement is of course the current sources in the Extended kit, but with the stock kit the ideal would be wirewound, preferably non-inductive. A tolerance of 5% is quite acceptable here.

We did early on try some 0.056uF Russian teflon caps across the 0D3 and thought it made a noticeable improvement.

[Mr. Lin]

Paul thank you, I appreciate your feedback and clarification of certain things I was apparently a bit confused about.  I have a basic knowledge and understanding of electricity and electronics, but no formal education in that area, and I find the sort of information you've just provided invaluable.  It's a learning experience for me, not just about the music.  

So that makes sense - I was wondering why certain DIY sites advocated the use of carbon film resistors in tube amps when you'd said they're noise-prone, but it turns out I just didn't understand exactly what you were telling me.  So I suppose the tight tolerances of the Riken carbon comp resistors are basically unnecessary in this application. But like I said, they look cool.

I have a couple of those Soviet-surplus Teflon caps - .1uf value - but they're huge, first of all, and second, I'm probably going to end up putting them in my Paramours at some point.  Until that time they're on the Hagtech Frybaby, and will probably stay there for about a month.

[Doc B.]

One of the salient features of carbon film resistors is that they can handle pretty high voltages. It's possible to find them with ratings of 500-750VDC. That's why we use them as bleeders in our power supplies.

[coca]

A very interesting read indeed. Just one note, I do believe that the Rikens with the gold plated leads are carbon film and not carbon comp. A very high quality resistor, nontheless.

Bernie.

[Laudanum]

I assumed that carbon comp. for the four 220 ohm resistors were chosen for the sonic merits.  Wrong assumption?

[Grainger49]

PJ has very specific reasons for using Carbon Comp (suppressing possible oscillations as grid and plate stoppers), Metal Film (loads, lower noise than CF) and Carbon Film (bleeder resistance).

I don't remember a carbon composition resistor being used for anything except a suppressor.

[HF9]

Lovely job Mr. Lin, I really enjoy seeing all the boutique parts in your build. I've been tempted by those beautiful red Jantzen caps (they got a good write up on Humble Homemade HiFi), but so far I've just played it safe and went with Obbligatos / Mundorfs or Ampohms, all of which I have gotten good results with. As PJ stated, people avoid the carbon comps due to noise and drifting which takes place over the years. Carbon films, especially the Kiwames, can get close to that "sweet warmth" of carbon comps without the issues mentioned. I can be a good idea to figure out if a resistor is in the signal path before you replace it, as boutique parts are not cheap and you want to maximize your investment, but the shotgun approach works too

Do you plan on any additional upgrades? Perhaps a stepped attenuator or a choke in the power supply?

[Doc B.]

I will suggest tantalum resistors if one is looking for the best sonics in the signal path.

[Dr. Toobz]

I've seen those green Kiwame resistors pop up in various discussions, and I've eyeballed them as a possibility for when I upgrade my gear. It sounds like the warnings about increased thermal/shot noise don't quite hold true (the manufacturer even claims that these are quieter than metal films, though I would be skeptical of such a claim). However, I wonder about excessive warmth or a "veiling" of the sound. Metal films are supposed to be more transparent. To the OP (Mr. Lin): the Kiwames were swapped out of your amp. Any strong feelings about them?

Tantalums seem like the ideal choice, but they are rather expensive....