Tube rolling on Foreplay III

[Laudanum]

Grainger, I think Helmut already has the FPIII up and running in stock form.   I cant offer him advice for his question (sorry Helmut) but just wanted to help clairfy what he was asking.

[Tickwomp]

I had been running a pair of nice RCA Cleartops for a year before recently trying a pair of Tung Sol Blackglass versions.  Like 'em a lot.  Highs almost identicle to the RCAs, but much more solid bottom end.

[Oberst Oswald]

I do have the stock Foreplay III built and am using a matched set of Cleartops in it.  The extended will get built in the next few weeks and I will do the full kit.  I really like the looks of the 0D3 (I'd like to keep it) and I'm almost sure I wouldn't hear the difference between that and the 12AU7 but anyway...

I use the Foreplay more as a variable voltage or gain connecting box so I don't have to switch wires to use either of my 3 headphone amps.  A music loving friend said that using a preamp before an amp with a volume control is degrading the sound and I would be better off taking the Goldpoints out of the Beta 22 & Bijou and use the Foreplay to control the volume.  Makes sense but as I have now it sounds OK to me and the Foreplay only has 11 steps with the Sweet Whispers.  Now comes the question...

Keeping as I have it now what is the proper way to adjust the volume controls?  The 3 headphone amps have different gains and the 4 headphones have different Ohm levels so, for example, I use the Foreplay to to make the input voltage hotter or colder on the Beta 22 (2X gain) when each headphone is used.  I built the Beta 22 to match perfectly with the 25 Ohm Denon 7000's but it don't go loud enough with the STAX SRD-7 SB transformer box (the SEX 2.1 amp will be used for this purpose when BH has the trans switching board for sale).  So I "feed" it more from the Foreplay and that decreases the travel of the volume control on the B22 and I turn it up so the STAX 'phones are at the loudness I like.  Is this damaging anything?  No problems so far the last couple of months.  Have the X-FI set at maximum because it's a software volume control so I know I have that right.  I adjust the Foreplay to suit my other amps likewise so the volume is at 12 o'clock or so with whatever 'phones I use.  In theory is this just plain wrong and I am really missing something in SQ or don't worry be happy...

[Paul Joppa]

To my mind, optimizing the signal voltage level in each component is far more important than any degradation from an extra level control. See my white paper on the Bottlehead - Community page.

Depending on the voltage from the source, use the Foreplay's input resistor to set the Foreplay gain for a substantial output at maximum volume; I'd suggest 2 to 8 volts full scale (the way digital devices are usually specified). Then set the headphone amp's gain so that produces the most loudness you'd ever want. Now you can leave the head amp's control alone, and use the Foreplay controls, whose range is adequate because you are using their whole range, not just the first 20% of it.