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The Williamson Amp, part one

The original Williamson hi-fi amplifier schematic as published in “Wireless World” magazine (UK) May 1947.  

The Williamson amplifier is considered one of the earliest hi-fidelity audio amplifier designs.  It is certainly one of the most popular audio circuits ever developed for DIY’rs.  Without fail I seem to turn up at least one home-brewed Williamson every year at the local estates+fleas.  A PS Dot Com reader from the UK sent us the original articles from “Wireless World” as published in 1947.   I have yet to build a pair of these myself, and the idea of starting ‘from the top,’ as it were, with the original design, is appealing.  A few things to note: check out the provision to balance the driver stage, and separate bias level and balance controls for the output stage.  Also: check out R25: the formula for determining the feedback loop resistor.  I wish every schematic included this notation.   NB: the ‘L63’ valve is simply a 6J5 – aka, one half of a 6SN7.  the ‘U52’ rectifier is a 5U4 or equivalent.  ‘KT66’ is a better-performing 6L6; feel free to use 6L6 or 5881 if necessary.

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Christmas 2011

Despite the hectic nature of the holiday-season, I am inevitably able to produce one piece each year as a gift for some person or persons near+dear to me.  This year’s recipient of the prize-winning entry in Connecticut’s Got Free Time! will receive this charming set.

I’d been thinking a bit about V. Gallo’s comment in Sound Practices #1…  see the previous post for the full details…  basically, the idea that ‘good hi-fi should sound like the best radio you’ve ever heard’ (as opposed to some supposed verisimilitude to an actual acoustic event).  Well, here’s an attempt at the best-sounding radio you’ve ever heard.   At the front end, two RCA inputs mix via fixed resistors to a single 100K pot, and then onto the grid of the voltage amplifer stage (6J5, the ‘single’ triode iteration of the more common 6SN7); this feeds one 6V6 via a gigantic paper coupling cap; in the power supply, a 5Y3 rectifier and R/C filtering with large (50uf) caps and an extra filtering stage before the output transformer for a n extremely quiet, stable signal.  The circuit is very similar to what you would find on the back-end of most transformer-mains-isolated AM/FM tube radios of the 40s and 50s.

The speaker is a 1950’s extension speaker, maker unknown; it has extremely nice finish work and detail; it is unusual in that both the front and back of the enclosure are open via grille clothe, creating a ‘bright’ and ‘dull’ side; position the speaker as-you-like for a very unconventional tone control!

The cabinet is 1×3 solid cherry with internal bracing.  Keeping with the ‘best-radio’ theme, the tubes, transformers, and brown Bakelite sockets are pulls from various Ancient Radios that have wandered into the shop over the years.  And yea it sounds great…

 

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Sound Practices Zine Archive Available on CDR

I was checking out this bro’s blog (or bros’ blog? lots of chick pics) recently and I came across an endorsement of the PDF version of Sound Practices magazine.  I had never seen an actual issue of Sound Practices (it ceased publication a couple of years before I built my first tube amp), but I had read a few articles that had been put online, and I had encountered much discussion of it in various online chat groups.  Seemed worth taking a look at.  I purchased a $30 (delivered) CDR containing all sixteen issues as a giant PDF from eBay seller n5Kat.  Not cheap, but all this scanning does take some time, plus the PDF has some useful navigation features built in.

Anyhow…  it arrived and $30 well spent.  You can see a list of some of the various articles contained within at this link.   Sound Practices is aimed squarely at enthusiasts of vintage hi-fi, experiementers, and hobbyist builders, rather than the much more electrical-engineering-oriented Audio Amateur/Audio Electronics, another publication from the same period which frankly tends to confuse me half the time.  Let’s put it this way,,,  there’s not a lot of math in Sound Practices.

So what’s the point.  If you’ve read this far in this post, you are likely one of my regular readers, and if you managed to make it back several times to this fairly niche website, I am pretty sure you would dig Sound Practices.  Still available for $30, world-wide shipping included, on eBay.

On a closing note… an unexpected bonus for me was discovering that one of my favorite writers on the subject of vintage audio-gear was a regular contributor.  I refer to one Vincent Gallo.   I’ll end with a bit from his first piece in the zine, surprisingly free from the (albeit hilarious) hostility that usually marks his writing:  what follows truly gets to the heart of why-antique-audio-equipment-matters, as well as a fundamental relationship between sound on the one hand and audio on the other:

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The BRDCSTR

Above: The BRDCSTR, a two-stage vacuum-tube microphone preamp inspired by classic 1940s broadcast audio preamps.  Single-ended design with a 6SJ7 and 6J7 tubes, massive output transformer, and only one capacitor in the signal path.  I have built more of these than any other design; people really seem to respond to the sound.  It’s pretty much the least ‘stuff’ that you can put between a microphone and your A/D convertor.  All the attitude of ancient tube studio equipment without the hum and the noise, and with much better frequency response.

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Astatic Microphones 1964

Download the complete eight-page 1964 ASTATIC microphone and phono cartridge catalog:

DOWNLOAD: Astatic_1964_catalog

Models covered, with text, specs, and photos, include:  hundreds of phonograph cartridges and needles; Astatic microphones model 332, 22, 225H, 335L, 77, 77-L, 788 ‘Metro’, 888 ‘Tempo,’ 988 ‘Vogue,’ Astatic 331,DN-50, UG8-DN50, JT-30, D-104, 513H, 511, 531, 150, 151, 10M5A, L-1, T-3, and 551 microphones.

Astatic was mostly known for communications mics, aka., voice frequency mics, aka, mics that were intended to accentuate the 300hz-3000hz frequency band.

See this previous post for earlier ASTATIC mic coverage.

 

Above, the ASTATIC 788, 888, and 988 studio mics, aka the “Metro,” Tempo,” and “Vogue.”  The 988 was the top-of-the-line and boasted impressive specs.  I have never come across one of these.  Anyone?

Above, the various ‘heads’ that were available to mount on the ASTATIC ‘squeeze-to-talk’ base unit.  See here for details. 

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Live DJ set this Thursday December 8

This Thursday 12.8.11 I’ll be doing a live set at The Outer Space in Hamden CT.  The Outer Space is the 21+ venue operated in conjunction with Hamden’s legendary “The Space.”

I’m appearing as part of BDUB’s Sway night.  I’ll be on around 830.   This will be strictly a vinyl-only affair… no surprises there.  Have a beer or four as i dig into the best of 2o years spent searching for the secret gems of Nixon-Era rocknroll…  for a preview you can check out my two recent appearances on WPKN FM.  Listen here and here…  and check this link for some recent mixtapes...

The Outer Space:  295 Treadwell Street, Hamden CT: Thurs Dec 8 2011

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Interesting Audio-Technology Mini-Exhibit in Philadelphia

Walking around Philadelphia I noticed this shop-window.  Wow these people really had my number.   The shop is called Art In The Age Of Mechanical Reproduction (h.f. AITAOMR), which is a reference to a seminal essay by Walter Benjamin.  Benjamin was interested in understanding how our concept of value in art was altered by the new processes of mechanical reproduction (offset printing, phonograph records, etc) which became widely available in the early 20th century.  ANYways… AITAOMR is a fine shop with appealling apparel and lifestyle items offered for sale.   They also market their own line of rustic flavored boozes you can sample in the shop  (sold elsewhere at licensed agents).

Turns out that the shop-window display is part of an in-store exhibit of audio-technology that was put together by record producer/engineer Bill Moriarty, who has worked with popular artists like Man Man and Dr. Dog.    It’s a fun tactile display that foregrounds some of the crucial basic processes we use in audio work: editing, mixing, reverberation, ‘effects processing,’ etc.

The exhibit is up for a few more days; you can read more about it in Moriarty’s own words at his blog.

 

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Exclusive Bonus Content (2) (aka: found in an old guitar case)

Teenage Pain

Is So Real

I purchased a chromed-the-fukk-out sixties no-name hollowbody for a few bucks at the flea mkt last weekend.  Nothing special, but marker’d inside the case was this piece of folk art.  Too bad it didn’t have a four-track demo of this kid’s music in there too.

Kinda reminds of the best haiku I ever heard:   “Fifteen.” Credit for this one goes to K.M.:

sitting in my room

metallica really rules

I am so angry

See here for more ‘exclusive bonus content.’

UPDATE:

SEE HERE for a film-version of ‘found in an old guitar case’

 

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(Updated: Link To) Live Radio Show: The Ladies of Psychedelic Folk: 11/14/11: 89.5 WPKN:

Monday November 14 2011: Tune in tonight to WPKN 89.5 on yr FM dial in Southern Connecticut/Northern Long Island: or listen live in high-quality at www.wpkn.org.  I will be appearing as a guest on Steve di Costanzo’s excellent program ‘Radio Base Camp’ presenting a show I’ve put together on the Ladies of Psych-Folk.   We’ll be listening to some classic and lesser-known gems from the late 60s, as well as more recent artists who have drawn inspiration from that era.  Steve had me on air back in June; you can check out that show here. Hope you enjoy the show.

UPDATE: Steve has added the show to the WPKN archives.  You can stream it until (insert personal favorite apocalyptic event) at this link.

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Open Studio Event 2011

This coming weekend: November 12+13 2011: we will be having another Open Studio event at our arts building in historic Bridgeport CT.  Forty artists and fine craftmakers will open their studios and exhibit their work and their work-practices in our century-old lace factory, and this is only one part of a larger Bridgeport Arts Trail going on that weekend (read some media coverage of the event here).   Believe-it-or-not, our dusty lil post-industrial town features not one but three very large art-space buildings, and there is some fantastic work to see (and hear…).  After you’ve come by to listen to some of my Recycled Champs, the Model 22277 hi-fi amplifier, and my latest development in all-tube mic preamps (w/ ancient RCA 76 tubes), be sure to check out the work (and amazing studio) of the photographer Tom Mezzanotte, world-renowned quilter and textile artist Denyse Schmidt, and all the odd characters that have assembled in this strange+semi abandoned place that we call BPT.  If you’re lucky, you might even get to commission some print-on-demand work from my wonderful wife E., who will have numerous print-publications of her work for sale.  Details and directions below.