Roscoe Primrose's 
Date of "Visit":
26 October 1999

the system


amp & crossover

DIY turntable, top view

right speaker, side view

right speaker, front view

e-mail to:
Roscoe Primrose

 Roscoe's web page

I've been tinkering with electronics since I was about seven, when my step-grandfather (who is an amateur radio operator and was an electronics instructor during WWII) gave me a 100-in-1 electronic projects kit.  My first serious stereo was centered around an old Eico ST-40 tube integrated amp that my father (an electrical engineer) built as a kit when I was in diapers.  I built my first serious piece of tube audio equipment (a low output MC phono amplifier) in 1985.  Due mostly to lack of time and inspiration, my system was based around a Harmon Kardon Citation II power amp into a pair of Acoustat 2+2 speakers from 1985 until 1997.  Then, in March 1997, I was inspired to build my current system after hearing my first SE triodes and horns system, which consisted of a tri-amped system with huge double-Onken enclosures with 2 Altec 515Bs per side, Altec 803Bs with Altec 288Cs for midrange, and Altec 811Bs with TAD 2001s for highs. Amplifiers consisted of custom made OTL amps (pentodes, actually), Wavelength Cardinal 300B monoblocks for mids and, I think, Fi 2A3 monoblocks for the highs. Sources included a Verdier turntable and an Audiolab (?) CD transport/DAC. I was hooked right on the spot! 

My current system is a constantly evolving creature, I build and try a new piece of equipment about once a month.  I tried bi-amping briefly, and while I think bi-amping may be the way to go, the $210 pro-audio electronic crossover I tried just didn't have the sound quality to measure up to the rest of the system.

I'm a Member of DC Area DIYers Club:

System's Components
Turntable: Homebuilt turntable based on a Rek-o-Kut K-33 platter/bearing (from about 1960), with a Kenwood DD turntable used as a motor with thread as a drive belt, a Magnaplanar Unipivot tonearm, Denon DL-301 low output MC cartridge.
CD Transport: Theta Digital Data Basic, upgraded to Data Basic II
D/A Converter: Homebuilt digital filterless, non-oversampling I2S bus input DAC, Audio Alchemy DTI 1.0 to convert coaxial digital from the Theta into I2S for the DAC.
Preamp: Homebuilt interstage transformer coupled tube phono stage, with a built-in 5 input passive line-stage.  Denon AU-320 MC step-up transformer.
Power Amps: Homebuilt direct coupled 2A3 (or 45 with the flip of a
switch) SE monoblocks, about 1-1.5W/channel.
Speakers: Two-way fully horn-loaded system with Altec 515B woofers in JBL 4560 bass cabinets, Altec 288B HF drivers on Altec 803B HF horns.  Crossed over first order at 780Hz with copper foil inductors and paper and oil capacitors.
Cables: XLO type 1 interconnects, homemade interconnects, Goerz, XLO and homemade speaker cables (three pairs necessary due to xover being external to the speakers).
Accessories: Ceramic cones under the speakers, wall hanging behind the listening position.

Roscoe's comments about his System:

AA: "Roscoe, how would you describe your system's sound?"
RP: "The system has a huge, incredibly dynamic sound, transients are much closer to realistic than most home stereos, even with only 1.5W.  Even for as big as they are, the speakers do a pretty good job of just disappearing and letting the music out.  The system seems to convey the emotion of the music very well."
AA: "Do you think there is room for improvement?"
RP: "Always!  Until it's perfect (which, of course, it will never be) I'll always be trying to make it better.  I could use a little more in the lowest and highest octave, and their is a bit of a frequency rise in the high midrange which is a function of the Altec 288Bs.  Also, the tonearm cartridge could use some serious help, I've had/used both since 1983/4."
AA: "Have you got plans for upgrading?"
RP: "Well, I've got one JBL 4550 bass cabinet, when I find another, I plan to use those, which should fix the bottom octave quite nicely.  I want to get a digital crossover, which will not only allow me to bi/tri-amp, but will allow me to do time alignment and frequency response correction (for both room and speaker anomalies) in the digital domain.  If I could find an SME 3012 tonearm cheap, I'd jump on that in a heartbeat.  I'm going to wait until after the SACD/DVD-Audio wars are over to do anything on the digital side."