One last Foreplay 2.1 post

[amioutaline?]

Thanks to Paul and Paul for the suggestions the project is finished and playing nicely.

I rooted around in my misc. wire wound stash and came up with just one under 10 Ohm resistor, a 1.2 Ohm 5 Watt Mills which made the filament voltage exactly 6.29 V! I may buy a lottery ticket.

The $5 dollar Alps Radio Shack pot now has the 100K attenuation shunted to ground. Full listening volume is at 11 O'clock and stone cold quiet. I took the voltage divider ground from the pot, instead going direct to the star. I wonder if that has anything to do with the quietness?

Tubes are JAN 6189W Sylvanias from 1984.

Simple design and good parts equals great sound. I started DIY'ng with the Foreplay and now, 15 years later, here it is again. Cool.

 

[Grainger49]

Nice work.  Interesting, the Foreplay is a very simple and clean circuit that was only slightly modified through three iterations. 

BTW, those are the same tubes I settled on for mine.

 

[amioutaline?]

The first time you search for a tube at Antique Electronic Supply and all you get is a few lines with the name and a price, no description you think, "no way I'm sending NOS money for a blind purchase". Than you do and get a quad of NOS Amperex 50's 12BH7s or the Sylvania 6189s in original boxes, both for a lot less than Ebay, maybe NOS. THe 6189s are really good tubes.

Steve Brown is talking me into trying a 76, maybe for a variation on the George Wright Foreplay design or perhaps the JE Labs. You're driving the Paramours with it, right? The 76 is a lot more linear tube than the AU7. And the bottle shape matches the 45s in my amp ;-}

He's looking at a custom wound Heyboer power tranny with a tap for a tube regulated power supply. Expensive. I have to pay for my Opthalmologists Summer Vacation first so we'll see.

 

[Grainger49]

My FP 2 is 12AU7s the drivers in my Paramours are 76s.

Bill, are you getting cataracts... fixed?  Or Lasic?

 

[amioutaline?]

Isn't Lasix what they give Thoroughbreds? I hope to see better, not run faster.

I don't know what you call it but the Doc tells me he makes a 6MM incision in the Cornea to allow an Ultrasound gizmo to break up the Lens into bits that are sucked out through the incision. Then a new lens is inserted.

One eye scheduled for the end of June, the other a week later. I have mixed feelings; my corrected vision is still 20-30 but the world looks like it's under water and my eyes feel like I left my Contacts in too many days. Wondering if I should get a second opinion on whether to do it now or wait until I bump into things?

 

[Paul Birkeland]

Steve Brown is talking me into trying a 76, maybe for a variation on the George Wright Foreplay design or perhaps the JE Labs. You're driving the Paramours with it, right? The 76 is a lot more linear tube than the AU7. And the bottle shape matches the 45s in my amp ;-}

There is some "missing" data in the 27/37/56/76 family tree of datasheets that makes them not suitable for replacing both 12AU7's in the foreplay I/II.  I know this because I did it, then wondered why tubes were only lasting a few weeks, then I ended up changing the circuit considerably to a single gain stage with an output transformer. 

Linearity between the two is very similar (the plate curves for the 76 have a shorter Y-axis, which makes them look better).

Still, the 76's are cool looking tubes, and early ancestors of the 6J5/6SN7, and are great to use for custom projects.

-PB