RCA 1428 "clinic." Notice bottles of Cote du
Rhone used for cleaning those dirty old diaphrams.

More RCA "Clinic." Steve says "if anything
jumps out of there, shut the top real quick!"

RCA "Clinic 1428B." Steve sponsored this one. For $50, everyone got to repair and then take home a RCA field coil driver. Thanks Steve!

Filmmaker Jonathan Weiss trying to convince Jeffrey Jackson to let him make a movie about an overambitious amplifier designer whose creation becomes alive and destroys an entire city. Jeffrey refused.

.

Sometime reviewer Laurence Borden sits in the shade of
his Panama, basking in the glow of thermionic emissions.

Larry Dobbins- "Yeah, so what if it doesn't have tubes inside? You got a problem with that?"

Few people know that Herbert "Voight Pipe" Jeschke selects
his automobiles (always Volvos) solely on the basis of Voight Pipetransport compatability.

A favourite warm up activity at the Tasting is playing "Catch That Speaker"in the parking area. Notice figure in orange in background struggling.

The "figure in orange" again, this time seen trotting up the
road with a large object, presumably a.....?

OswaldsMill, epicenter of tube and horn geekdom in the known universe for one glorious weekend per annum. Valet parking not included.

Dave Slagle of Intact Audio and circuit maestro Dave Cigna trying to program the artificial life form into sentience (brought by Jeffrey Jackson, to left.)

Hans Dietze, former RCA Cinema Products engineer and designer of the last incarnation of the inimitable RCA LC1 Duo Cone driver, the LC1C, delivers a talk on his work-you can listen too, just click on the audio link.

Paul Scearce and wife opted to bring a future audiophile (held in arms) for indoctrination this year, in lieu of the usual living room system (literally.)

Early Goto cast horn brought by Steve Blair along with the corresponding compression drivers, very similar to the WE555 in design, but permanent magnet, flanked to the left by an RCA MI1425 field coil cone driver.

Steve Blair was desperate to get his finger out of that throat. He was warned.

Bill Woods setting up an ATB acoustic measurement system to measure speakers at the Tasting. The computer is siting on a "1/2 horn" made for a JBL LE8ht. Low end is 90dB at 45HZ!A number of measurements were made of interesting hard to find speakers....a few are...

A number of measurements were made of interesting hard to find speakers....a few are...

The Mill System RCA Theater horn with all RCA HF drivers.
Goto 555w -like driver on 300Hz Goto metal horn
Herb Jeschke's Voight pipe system
The Cogent field coil bass driver in a custom basshorn made just for Oswald's mill 2006 tasting!

Bill Woods measuring the Goto driver and horn. Sitting next to it is the Cogent, for size comparison purposes only.

Steve Schell of Cogent True To Life Loudspeakers, leading a twelve step Bass Reflex Anonymous meeting. Actually, you may listen to Steve's talk on progress with the Cogent field coil horn system by clicking the link. Free yourself from direct radiating loudspeakers today!

Steve Schell of Cogent doing listening tests inside the bass horn. Extremely dangerous- don't attempt at home!

Cogent bass field coil driver prototype.

Cogent field coil bass compression driver, the only one of its type in the world, attached to the experimental bass horn.

Side view of the Cogent field coil bass compression driver prototype unit. Production scheduled for 2007.

9" basshorn constructed for use at the Tasting for the Cogent field coil bass compression driver and the RCA MI1425 cone field coil driver.

Fire in the Hole!

Doug Piccard- "The linestage in the salvaged rackmount chassis is a TX coupled buffer. The TX's are custom Intact Audio items. Wound bi-filar on gapped Ni cores, they're -1 dB at 2 MHz! The DCR of the primary is used to bias the cathode follower, a hybrid cascode utilizing a 5687 section and an IRF820B MOSFET per channel. The cascode/faux-pentode circuit allows a relatively ripply B+ while remaining quiet. Maximum gain at wide-open-throttle is 1:1."

Doug Piccard's pp amplifier- "The stereo amp is designed around a new circuit called E-Linear. This circuit utilizes the Ultra-Linear taps on the output transformer to provide balanced voltage feedback to the long-tail-pair input stage. The finals are Hytron 1269's running Class A with 30% U-L. The custom outputs are wound by Heyboer Transformer. They are 10k a-a and are patterned after the coil geometry taken from the Peerless S-265-Q, with modifications enabling their use in the E-Linear circuit. Power is about 12 Watts per channel.

This amp is an exercise in PP. PP built to the same standards that got SE such a following during the rebirth of valve audio. Class A bias, choke input power supply, only high-quality film capacitors, Thoriated Tungsten, directly heated finals and no loop NFB."

Jim Dowdy's contribution- "My amp uses the copper plate GM70 in a single ended configuration; providing about 13 watts of power. The parafgeed output transformer and plate chokes are by Magnequest. The front end is a 3C24/25T loaded by a nickel plate choke from Intact Audio. The power supply utilizes an L-C-L-C-L-C filter; rectified by a 4 tube bridge of 6CM3 diodes. DC filaments are also L-C-L-C-L-C filtered. The power supply weighs over 100 pounds. B+ at the plate of the GM70 is approximately 730DCV; and approx. 380VDC on the 3C24/25T. All tubes run in self biased mode.

Dowdy Lama trying to figure out where that wire went.

Dowdy Lama (Jim Dowdy's) GM70 amplifier's output stage. This amp was extremely impressive.

Frank Clooney with a pair of extremely rare Western Electric 753C monitor speakers.

Shoot out between the Western Electric monitor system and a RCA SL12 fullrange driver mounted in a similar sized ported enclosure. A pair of RCA SP20 Sound Products 6V6 amps were used for the A/B test.

Inside the Western Electric 753C, original down to the insulation- The WE753C Monitor uses a 713A compression driver on a bent horn and a 15" Jensen/Western woofer.

Herbert "Voight Pipe" Jeschke with his latest creation, a very successful experiment to overcome the one drawback of the single driver VP, its uneven response in the low end. Two similar drivers at ½ octave distance smooth that response and the additional tweeter takes care of balance in the high frequency realm.

Another view of the Voight Pipes using the same extremely inexpensive Radio Shack full range driver Herbert has been experimenting with since the first Tasting.

Herbert Jeschke brought "two 300B SE amps of very similar construction: Solid walnut chassis with 3/16 copper ground-plane. The classic 300B output configuration driven with Interstage Transformers, DC current regulated filament supply and dual choke Pi filtering for B+ with oil-capacitors. The driver-stages, both DC filtered by regulator “glow” tubes make the difference in the two designs. One sports ancient mesh-plate pentodes of German origin in triode mode, which impart a sweet, emotional flair to the otherwise flat, balanced response of this amp. The second one replaces that rare mesh-plate driver with a made for TV octal pentode where their screens are used in place of the plate, thus running them like low mu “mesh”-plate triodes. This driver configuration surprises more with its ease and accuracy of music reproduction. Both amps are pampered with ALPS pots and E80CC input stages coupled over Sprague oil-caps to the drivers. Not an easy task to make a choice of preference between the two, but over several listening sessions it turns out the accurate audiophile prefers the screen-plate driver, while music and tube lovers dote for the mesh-plate."

Jack Roberts gave a Marine Corps style lecture on the need for discipline when constructing tube amplifiers.

Jack Robert's 300B SET. An excercise in restraint, a remarkable amplifier sonically, given its size and economy.

The use of large transmitting triodes like the 304tl in SET mode portends a shift upwards in power from previous thresholds such as the GM70, 845, and 211. Scary thought where this trend may take us.

Jeffrey Jackson's 500lb SET 304TL amplifier.

Jeffrey Jackson plans to offer this as a beginner's kit project. Well, not really. A diorama for nuclear fusion? Perhaps... Interpretations were numerous. The sound, enormous.

Dave Slagle of Intact Audio and a dealer working out orders for Jeffrey's new 304TL amp.

I made a joke in the last Tasting site about Jeffrey Jackson "wondering how much his amp would have to weigh to get to two watts?"
Evidently, I should be more careful about my jokes.

In his bid for revenge vis my lighthearted jocularity, Jeffrey brought this firebreathing monster of a SET. Notice the little Yoda figure sitting atop the transformer? You need the Force to Be With You just to power this thing up.

Jeffrey Jackson of Experience Music showing where children, the uninitiated and really just about anyone else should not place their fingers.

Nothing like mercury rectifiers (866.)

Chassis #2 of the Jackson Monster.

Ken Lochridge doing a postcard pose with the Mill system. Or at least the business part of it.

The Mill power amp rack on the left. From top, breadboard driver amp on wood, driver tube is the ancient European mesh plate AL4 pentode in screen grid mode (thus functioning as a triode) driving a 300B SET, driving the MI9355 RCA 845 push pull amps below. Yes, a SET driving a PP output stage.
A handmade passive attenuator/linestage is in the rack to the right, containing CD player (TEAC VRDS10) and sundry other items.

The Mill's House Amp- Brutus. RCA MI9355 845 push pull booster amp originally created for the Fanstasia road show in the late 1930's. Rectifiers are mercury vapor 866's.

Is this the mysterious object toted by the "figure in orange?" Inquiring minds want to know.

Closeup of Carter's NotSoMatic.

Frank Clooney's WE 753C Monitor (left) with the Mill's attic system, RCA SL12 fullrangers in ported enclosures with RCA SP20 6V6 amps, components engineered to work together as part of RCA's "Intermatched" line of components from the late 1950's. Frank could not be persuaded to leave the WE's at the Mill, unfortunately.

Randy Carter explains his breadboard linestage, the notSoMatic, designed for testing candidate tubes (globe 27, 112a, 71a, 1626, etc.) with a gas regulated B+, parafeed chokes, multiple filament supplies, and a hinged side for easier connection of replaceable signal modules... Randy also tried to keep the demos moving and administered the safety lecture for Jeffrey Jackson's table full of high voltage: Randy - "Don't touch it, you'll be sorry..." Steve Blair elaborated - "We'll be sorry... you'll be dead."ry other items.