Sector 7G, aka Douglas Piccard, in his own words-

"This year I brought a linestage and a pair of monoblock amps. The linestage is a simple 12B4 triode gainstage with a lot of support. 816 Mercury vapour diodes feed a single L-C filter of 45 Hy and 100 uF. An Amperite 115NO60 delays the power to the plate TX to allow the 816's to warm up. There's DC for the 12B4's heater underneath, also L-C filtered. There are two video pentodes each, forming an active load/mu-follower buffer. Output Z is so low that it doesn't care what sort of patch cord feeds the amp. Currently in use at home are the originals supplied with the DV563A player...so far nobody has been able to tell the difference between them and more exotic cables!

The amps are built around the radial transmitting pentode, the 4E27. The amps are built on two chassis, and connected through a 4' long umbilical and Amphenol MS-series plugs. They're light in DunkerFactor, at around 4 pounds per watt( and ~40W output ). Special custom output transformers wound by Heyboer are modified Peerless S-265's. They feed the 4E27's screen grid from the 40% tap, and the E-Linear cascode driver from the corresponding 30% tap. The cascode driver is built with the Russian 6H6P and Fairchild's now-obsolete FQP1N60 MOSFET. I think I'll have less trouble sourcing replacements for the WWII-era 4E27's than those MOSFET's. With B+ of 560V, they're running full class A, and slightly power limited at that. Those finals *NEVER* get cut off. 

Thanks again for a wonderful time this year Jonathan. I just don't have the words together to properly thank you for inviting me to be part of that experience. The best I can do to repay you for such hospitatity is to bring my A Game and and make a positive contribution. Here's to what fun we'll all have next year!"

Herbert came with the 300B amp he already introduced in the 2006 Tasting, but with a new twist. The amp itself is built on a heavy walnut chassis and 3/16 copper  ground-plate. The classic 300B output configuration driven with Jack Elliano Interstage Transformers, DC current regulated filament supply and dual choke Pi filtering with oil capacitors for a 450Volt B+. The driver stage is filtered by regulator “glow” tubes to 210Volt for the anodes of an ancient mesh-plate pentode in triode mode of German origin driving the IT, and for the E80CC input tube couplet to the AL4 driver with a Sprague oil-cap. The output however was configured to drive a new set of Voigt pipes through 12uF oil-caps in parallel feed, using the OPTs as plate chokes.

Wide shot of Jeschke 300B amp for driving high impedance speakers. But notice the tubes- here is Herbert's commentary-

"Like a river in constant change, who gets its waters from many streams and creeks, this work in audio owes a lot to the Oswalds Mill crew and friends. This time while we were listening to this system Jeffry Jackson offered his globe 50ies to plug in place of the JJ 300Bs. The current regulated filament supply afforded by its nature a voltage close to specs, and the 300B circuit with cathode resistor and IT drive made a good environment for the 50ies needs…… The sound, what can I say, this setup operated pretty darn close to overall satisfaction already…but with the 50ies….well the music just reached and touched my innermost,….reached across the 40 or 50 years ago it was recorded becoming the now….music reproduction
achieved."

The Voigt pipes, a new experiment with 5 oval Philips speakers in series each having an 800 Ohm voice-coil for combined impedance of 4000 Ohm! The sum total of the 5 fullrange Philips drivers in each VP connected straight from the output tube plate separated only by the oilcap is stunningly more than any one of the drivers can offer. It gives extended response in the low end and superb imaging with a very agreeable midrange and good high extension.

Jeffrey Jackson, aka Experiencemusic.net, in his own words on the Tasting this year and his contributions-

"I love the Mill. It is *the* audio gathering of all-time... nothing else comes close. And, when I am getting ready for the event, I always call our gracious host to ask what I should bring. The conversation this year went something like this:

Me: "So what should I bring?"
JW: "Whatever. It doesn't really matter."
Me: "Great. That's easy."
JW: "What are you listening to?"
Me: "blah blah blah" for a few minutes....
JW: "Then bring all that."

No problem, I thought, I just have to bring "all that"...

I brought a rather ambitious front end. I love the Miyabi phono cart for its way with music. It can make you cry and then pull the amazing feat of teaching you a lesson for crying via Black Sabbath. It came with the matching yummy nickel 1:50 step-up that Slagle wound for it. The phono is the famed LCR EQ... all nickel iron and teflon caps... two stages... direct coupled... triodes, of course... even has had a few DHT's in the second position. The first was the obscure euro LP2, and now it is the modern marvel EML 20A. I think this two chassis, seventy pound beast has more than twenty pieces of custom wound iron in it... mostly nickel... a few amorphous... The chassis is from a giant slab of Bloodwood that I found locally. The tops are a solid piece about 18" wide...

The line stage is also from that bloodwood. It uses a golden oldie, the 71A... of course, RCA globes... this is the Mill, after all... you have to bring something RCA. It is my standard line stage design. After building so many line stages, I now know that it is like cooking... flavor with ancient DHT's. The 71A is more beautiful than the 45... but the 45 has much better dynamics... how much spice do you want? after dinner sipping stout or afternoon grilling with a nice pale ale? your choice... I brought stouts to the Mill.... :^)

and then there is the mono GM70 push pull amp that I have been working on... This was a request from Jonathan. He always likes to hear push-pull amps from single-ended builders. He knows that you will get the power and control of push-pull, but with the tone that the SE guys have to have. In a way, though not intentionally, this amp is a lot like Brutus, the Mill house amplifier. It is big transmitting triodes... with a single ended driver... One crucial trick is the phase-splitting. You have to use good iron and listen carefully. On this amp I used *many* of my single-ended tricks... notice those Western Electric thyratrons... and the big input choke... low DCR supply... and big white thoriated tungsten filaments... Yes, I still like my five watt amps, but on more than one speaker of my own speakers, I'd take the monster GM70 push-pull amp. Power and control equals big thrills... even simple guitar enjoys the highlighted dynamic contrasts... you can sway and play right along-side Muddy Waters..."

"JE Labs deluxe preamp – phono circuit is based on the classic RCA found at the back page of most tube manuals, 2 stage cascaded 6SL7/5691s with passive RIAA equalization in between loaded by a 250K ohm volume control. Cathode biasing is through Nickel metal hydride batteries. Line stage is based on the Berman SP13 running at my chosen operating points (medium current) - a type 76 voltage gain triode direct coupled to a 6SN7GTB cathode follower. Copper foil in oil signal capacitors and carbon composition resistors, power supply is external using a conventional choke loaded input filter rectified by a 5V4 rectifier for a raw B+ of approximately 320V, DC on filaments. JE Labs SE171A – uses a type 76 first stage direct coupled to a 6SN7GTB driver stage capacitor coupled (copper foil in oil caps) to the grid of a Type 171A directly heated triode loaded by a 5K ohm primary Tango H-5S output transformer. Power supply is a conventional C-L-C rectified by a type 80 rectifier. Output = .790 watts per channel.

Both topologies are very Old School and very similar to those published in my Sound Practices Issue 17 Homebrewer article."

The petals of the midrange horns are made of thick card stock paper. Once I taped the petals of the horns together, I was able to build up the paper mache on them without a mold. Taking the phase plug into account, the area of the horns follows a tractrix expansion from the diaphragm to the mouth of the horn. The midrange horns didn't require a mold, so I was able to flare them around the phase plug at the throat. I used old Washington Posts for the paper mache horns, but feel free to experiment with other publications. The midrange horns have a frequency response of 1.5kHz to 7kHz.

The bass and treble amps use essentially the same circuit. the bass amp simply has larger output transformers and a slightly beefier power supply.

The amps use dual triodes from input to output, with one section of each tube for the left channel, and one section for the right.

The output tubes are 6336A dual triode regulator tubes.

The plates of the 6336A are made of graphite, and can dissipate 30 watts each. With the 5 amp filaments, that is more than 90 watts in an envelope the size of a KT88.

I didn't realize how bulky the meters for the bass amp were until after I assembled the circuit. Fortunately, I was able to just squeeze them in by mounting them upside down. The meters monitor the bias current of the output tubes.

"CGV-0606
 
The CGV-0606 is a single ended amplifier using a 6SL7 and 6L6GC per channel. The 6SL7 is configured for amplificaiton in one half biased at its most linear point, with the second half directly connected as a cathode follower. The 6L6 stage is biased in tetrode mode for maximum power efficiency. They also share one cathode resistor for fixed bias of both. The screen grid's voltage is derived from the preamp B+, which is about 250 volts. The output transformers are a pair of 3K primary Hand Wound brand transfortmers. The resistors used are NTE brand metal film, and the capacitors Sprague 715 orange drops. There is global feedback of about 10dB. For an overall voltage gain of 11. The amp uses a 5Y3 rectifier to keep all the tubes of the same vintage. No choke is used for the B+, but a 390 ohm 10 watt resistor is used.
 
MAG-1515
 
A 15 watt per channel push pull EL84 based amp based on the old Magnavox Console tube amps of the late 1950's to early 1960's. The amplifier in this case is very much the original design with very few exceptions, they being a slightly larger coupling capacitor in the phase splitter, a larger filter capacitor and metal film resistors. The otuputs are connected UL also, as opposed to straight pentode. The driver tubes are 6EU7's. This one also uses tube rectification by means of the 5U4. Hammond iron is used throughout."