Transformer-As-Signal-Processor: Another Custom Build

Recently shipped this bespoke four-channel unit to customer P.G.  PG sent me a pair of UTC A20s and a pair of Triad HS-66 600:600 transformers; he wanted a finished piece that would allow him to switch the transformers in-and-out of a signal path easily.

For an explanation of the ‘transformer-as-signal-processor’ concept, see this previous post concerning a similar custom build.  P.G. wanted his unit built as a two-space chassis so that he could add a third pair of transformers in the future if he wished; the front panel was precisely measured and punched so as to allow this to be done in a visually harmonious manner.

Above, the inside of the unit.  Belden 9451 wire and the same 12,000 watt (no typo) 4PDT toggle switches as the prior build.  So how does it sound?  For those of you who are curious about commissioning or DIYing a piece like this, here are my impressions.

First, the ‘hard facts,’ measured using sine waves at +10db.

UTC A20: Insertion loss approx. 0.2 db.  down 1 db at 12hz, down 1 db at
65khz.  Otherwise flat.

Triad HS66: Insertion loss approx. 0.1 db.  down 1 db at 10hz, down 1 db
at 60khz.  Otherwise flat except for a bump up around 10k.

As fast as listening test (with music, not test tones): and this is obviously very subjective: the UTCs are very very subtle.  Bass is little more organized but it’s really hard to say. They are just too perfect I guess.  If they are run them at full protools level (+22) the user will likely hear some color, as it is outside their stated linear range. But at +10 there is little effect.

On the other hand, the Triad HS-66 definitely have a sound: at first I thought that they were bass shy, but the sweep test denies that.  To my ears, they make everything sound more forward and aggressive.

Phono Equalizer Design Circa 1950

Download a two-page article from RADIO ELECTRONICS, April 1950, on the subject of Phono-EQ design:


These are not phono preamps, so-to-speak; they lack sufficient voltage gain to bring phono-pickup-level up to line level.  Nonetheless some interesting info in here which might be useful to those of you DIYing tube EQs out there.   An interesting artifact from the era prior to RIAA standardization.


There is still more work to be done

As I was packing my belongings for a new, quieter life in the Eastern Atlantic, I came across this curiosity.  A Blade-Runner themed guitar.  But.  Not even the ‘famous’ (relatively speaking, of course) Guild-Brand Blade Runner Guitar.  Close analysis of this obscure piece of content revealed a deep truth: there is still so, so much to be learned from digging thru endless piles of ancient audio-themed papers.  I cannot stop.  Yet.  There is still more work to be done.   Let us now examine the facts.

The Guild ‘Blade Runner’ (at left; source) utilizes the actual Blade-Runner-Film font on its body, suggesting that the Guild guitar was actually licensed by the film’s producers?

Initially, it seemed incredible to me that a second guitar-maker would enter the market with a guitar named after the film Blade Runner; which, as great a film as it is, features neither a guitar nor any guitar-music for its duration.  What could explain this seemingly totally unnecessary redundancy in the guitar marketplace?  Perhaps the answer is more complex than we have yet realized.  Perhaps the ‘licensed’ GUILD-brand Blade Runner Guitar was all too content to align itself with the orthodoxy imposed by the film’s producers (the same producers, naturally, that insisted on the inclusion of the humanizing ‘voice-over’ in the film’s theatrical release).  Perhaps the ARIA-brand Blade Runner guitar was part of an alternate explanation of events, one that perhaps comes closer to the truth?



Above: at left, Daryl Hannah as the character Pris in the film Blade Runner.  At right: Some Model as Some Future Lady in the Aria Pro advert.  The similarities beg the question:  Is the man holding the guitar a surrogate for Roy Batty, the character with whom Pris was aligned in the film?  Or is the man-with-guitar intended to represent Deckard, the protagonist of the film? He definitely seems to have a stronger resemblance to Harrison Ford’s Deckard than to Rutger Hauer’s Roy Batty; yet the sunglasses are a confusing and highly suggestive twist.  In the grand tradition of Blade Runner Conspiracy Theories, I would like to put forth the following thesis:

In the so-named ‘Aria Thesis,’ Deckard is the 6th Nexus replicant; here he is shown, before the crash landing, with Pris; Batty was in fact an interloper who usurped Pris’ affections after attempting to kill Deckard prior to the crash, in fact causing the crash.  Batty attempted this murder by his indicated choice of killing technique: crushing the eyeballs into the brain. The Aria corporation signals this violation by covering Deckard’s violated eyes with their branded eyewear, eyewear that appears nowhere in the filmed narrative.  In the Aria Thesis, the police force discover Deckard’s near-dead body; re-suit him with replacement eyes and unicorn dreams, and then set him to the task of capturing his former associates.

Please direct all question and/or comments about this post to these guys.

Or these guys.

Good luck.


That’s it. I’m done.

There is no reason to go on.  I have found it.

The all-time, ultimate, absolute pinnacle of guitar adverts.

Clearly, my work here is done.  In case you missed it:

Jungle animals with red ‘Laser-eyes’? Check.

Pink Bandana tied above the elbow, to indicate that the wearer is looking to sell, rather than buy, (PCP? Ritalin? Advil Cold and Sinus?)? Check.

‘One-upping’ the classic EVH-style ‘Axe’ by adding a pointy headstock?  Check.

Pop-metal androgyny? Check.

The ‘Lost Chord’?  Check.

Utterly unconvincing photo-collage work that could only possibly correspond to the psychological landscape of a 12-year-old boy?  Check.

‘Heavy Metal’ typeset in actual-metal? Check.   Let’s see that one more time.

Thank you all for supporting this website over the past two years.  I am retiring to a cottage on the Aran Island of Inis Mor.  Take care.

Previous Hondo coverage on P S Dot Com

Fascinating Collection of Television Station IDs circa 1951

Today on P S Dot Com: a fairly comprehensive survey of television station ID graphics circa 1951.  Widespread full-time telecasting did not take place in the US until 1948, so you are seeing the face of a relatively new industry here.   I realize that this post has little to do with sound, but television, as it is broadcast,  is at least 50% sonic; those of us who work in television are all-too-aware that we design programming for a distracted audience; I.E., programs and adverts are designed to deliver messages to audiences that can hear the set without necessarily seeing the screen.   The importance of television broadcasts in creating the sound-environment of the twentieth century is immense.  Anyway, here’s a trip back to the earliest days of mass-TV broadcasting in the US, and a fascinating look at how the early TV broadcasters saw themselves, as-it-were.  If anyone has a link to an online archive of the sounds that accompanied graphics such as these, please do let us know.

Many, many, many more follow: click the link below to READ ON…

Continue reading Fascinating Collection of Television Station IDs circa 1951

UPDATED: Emory Cook, Binaural Recording Pioneer

Emory Cook records Long Island Sound at Shippen Point, Stamford CT (with two mics, of course): 1954.  He is using a Modified Magnecorder.  This, and all other reproduced materials in this article are courtesy T.Fine.

***UPDATE: I’ve added a variety of links to relevant Cook-resources at the end of the piece. ***

Thanks again to contributor T.F. for providing an extensive collection of documents relating to one Emory Cook, inventor, Connecticut businessman, and pioneer of binaural sound.  There is much too much information contained within these primary source documents for me to adequately paraphrase, but here is a quick synopsis.

Cook (at left) attended MIT, briefly, in the 1930s, and received his electrical engineering degree (minor in communications) from Cornell immediately following.  After an incomplete stint at Columbia Grad he went into industry as an engineer, primarily radar and some broadcast work.  Excited by the postwar prospects of magnetic-tape recording and the general explosion of sound-recording technology of the late 1940s, Cook then began his own enterprise of designing and manufacturing sound-recording hardware which he claimed offered vastly better performance than competing  products.  This led, in short turn, to Cook Records, which issued over 140 LPs over the course of two decades.

Above: Cook’s preferred solution to the problem of creating a fully mono-compatible stereo LP disc record.  Two separate cartridges with ample spacing each track a separate groove.  The disc could therefore be played on any mono machine without issue.  Click here for further information on this forgotten technology.

Cook achieved the widest recognition for his research and development of binaural sound apparatus.  Binaural sound is a specific type of stereo (two channel synchronized) sound which specifically attempts to capture sound in a manner consistent with the hearing apparatus of an unimpaired (IE., having full use of both ears) human animal.  Stereo sound is much broader field; truly, any system in which two discrete channels are programmed and synchronized for playback on two separately-located transducers could be described as ‘stereo.’ As the past sixty years of electronic media history has played out, true Binaural sound techniques have had limited application and/or consumer appeal, but it is critical to recognize how the field of stereo sound was largely birthed by individuals such as Mr. Cook who were so taken by the attempt to recreate, electronically, the biological process of two-eared hearing and the spatial-localization that it affords.  Beginning in the early 1950s, Cook published a number of papers and articles on the subject.  I would encourage you to read them and get the story from the horse’s-mouth, as-it-were:

DOWNLOAD: Tele-Tech-5211-Emory_Cook-Recording_Binaural_Sound_on_Discs 1952: Cook explains and defends his two-cartridge stereo LP system and offers a design for an economical stereo amplifier.

DOWNLOAD: Emory_Cook-Binaural_Disks.  A more consumer-oriented essay which covers similar material as the prior.

DOWNLOAD: Emory_Cook-AIEE-530616-Binaurality.  A technical paper on binaurality delivered in 1953.  T.F comments:  “(it is) interesting how (Cooks’s) summary of past technology ignores Blumlein’s 1934 patent.”

DOWNLOAD: High_Fidelity-5410-Emory_Cook. A largely biographical piece from HIGH FIDELITY, 1954.

IN ADDITION: The Journal of the Audio Engineering Society ran an excellent essay by Cook in their very first issue, January 1953.  Since the AES depends on the sale of their previously published material for revenue, I do not think it suitable to offer that article here; you can, however, purchase it directly from them.

Above: Cook’s suggestion for creating a listening environment for Binarual audio playback.  Contemporary thinking seems to regard headphone-listening as the only suitable mechanism for Binaural playback; Cook’s advocation of loudspeakers suggests that perhaps the difference between ‘binaural’ and ‘stereo’ need not be quite so rigid.  T.F. comments: “Cook’s explaination of Binaural…is somewhat different from the 1930’s theories of Alan Blumlein. Cook always assumed speakers, and also the right triangle of two speakers and a listener in the center. “

Cook spent considerable time and energy traveling the world to capture sound-events using the specialized equipment that he developed.  Like many early audio pioneers, he was greatly interested in the power of sound and sound-recording itself; musical recording was an important part, but only a part, of what he saw as a world of exciting sounds to capture and make available to consumers through recorded media.

Above: one of his less high-brow offerings.  Click here for liner notes: COOK01071_Burlesque.

Above: a more concise summation of the technical recordist I have not seen.  My $.02: I can’t wholly disagree with what Cook states here, but perhaps it is wiser to recognize that his conception of a recording engineer is one of many valid approaches to that field of endeavor.  Perhaps in 1953 this was tougher to see.  It’s certainly not irrelevant in our current moment, though; Cook’s viewpoint reminds me very much of contemporary recording great Steve Albini, who’s extreme preference for documentary-style production has led to some great (Nirvana, Palace) and not-so-great (Jarvis Cocker) albums.  Sometimes it’s the right move, sometimes it ain’t.

Cook remained very active in audio production and technical work at least into the 1970s; above, an image of his factory circa 1970.  Cook Laboratories offered a range of services including a recording studio, cassette and record duplication and stamping, A/V production services, and specialized equipment manufacture.

For a fascinating view inside the above-depicted plant, click below to download their circa 1970 catalog of services.

DOWNLOAD: Cook_Laboratories-1960s_brochure

There is a ton of other information online concerning Cook; here are some good places to start.   Cook passed in 2002 (click here for his obituary as published by the AES) and the catalog of recordings that he controlled is now owned and archived by the Smithsonian.  In fact, you can purchase the ‘Burlesque’ recording depicted above from them.  Cook’s Wikipedia page was apparently created with input from a former employee; if anyone out there worked for Cook at his plant in CT, please drop us a line.   I also welcome any substantiated corrections to this piece.  And I look forward to a heated discussion of the merits and/or fallacies of ‘binaural sound’ in the comments section.

Thanks yet again to T.F. for making these rare archival materials available to all.  For those of you unacquainted with T.F. and his rather unique perspective on the history and development of commercial stereo-sound recording, please click here.  

Marantz 7 Phono Pre/ Passive Line Preamp

Above: a  Marantz 7 stereo phono stage built for stand-alone use.  See this link for an earlier build of this same circuit, along with an explanation of exactly wtf a phono preamp is (for my 7 or 8 non-technical readers).

The major difference with this build is that I included a 2nd set of (passive) inputs and a volume pot.  This is to allow the user to connect both a phonograph and a 2nd line-level source, select a listening source, and control overall volume level ahead of a stereo power amp.  I also used a tube rectifier and a choke this time.  The piece sounds fantastic.

Stereo phono preamps are fairly time-consuming to build, and small differences in layout can have dramatic effect on the overall performance.  Here are a few snapshots of the process.

Hammond steel chassis, punched-out using Greenlee hand-punches

The underside of the unit following mechanical assembly

Initial wiring.  I always start with the ‘no-brainer,’ rote wiring tasks:  First, the 120AC wiring.  Followed by the B+ supply.  Followed by the Filament supply (if any; here you see the DC filament supply constructed at the left of the turrett board).  Finally, any passive audio-control wiring (the switch, pot, and Belden cable on the left). I wire up each one of these sub-assemblies and test each one; having 100% confidence that all this stuff is functioning properly makes it a lot easier to troubleshoot and vague performance issues once the piece has been fully wired.

…and done.  It’s hard to see how many components are mounted on the tube sockets, but trust me, it’s dense.  It never ceases to amaze (annoy) me how complex phono pres end up being.  The schematics look so simple!

eBay Alert: Lot of very rare Capps Condensor mics plus Altec ‘lipstick’ pair ending soon

Ending very shortly on eBay: a pair of 1950s Capps Condensor mics PLUS a pair of Altec Lipsticks (no power supplies).  Current price for the pile:  $231.  Caveat emptor, certainly, but for that price yr doin great if even one of ’em works.  I am so, so tempted.    Click here for the auction.  And click here for some period info on the very obscure Capps condensors.

Excellent Article on Larry Scully and the Variable-Pitch Lathe c. 1956

Download a six-page article from HIGH FIDELITY 1956 concerning the history of the Scully corporation of Bridgeport Connecticut, including an explanation of the significance of the variable-pitch Scully lathe.

DOWNLOAD: High_Fidelity-5612-Scully_Sm

At left: Larry Scully circa 1956.  Thanks to reader TF for this very interesting piece.  As I have mentioned before, I drive by the old Scully factory nearly every day on my way to work at Gold Coast Recorders.  I had been hoping to uncover some history of this once-great Bridgeport institution and this article certainly sheds some light.  Some interesting bits from the article: in the 30s, Scully briefly ventured into the manufacture of P.A. equipment.  And beer coolers.  Also of note: the price of a Scully lathe in today’s dollars?  $72,000.

Previous Scully Coverage on P S dot com:

The Plant

The Model 601 Lathe

Some very neglected Scully 280s

Three interesting Hi Fi Amps circa 1948

Download a three-page article from the September 1948 issue of RADIO ELECTRONICS on the subject of ‘Three Straightforward Amplifiers.”  Author is John Straede.  Schematics ETC are all included in the download.

DOWNLOAD: Three1948Amps

Above, the most interesting of the bunch: a single-ended 6L6 amp which uses fixed bias for the output stage.  I have never seen a fixed-bias SE power amp.  Seems like this could yield some unique overdriven textures for guitar applications.  Worth a look.

Above, the 13-watt 6V6 PP unit.  A couple of things to note: the input stage uses a 6U6 pentode.  I have never come across a 6U6.  Anyone use one of these?  Also: the 6U6 stage uses ‘Grid Leak Bias,’ in which the cathode is at ground potential and yet no DC bias is used on the grid.  I have never tried this type of bias.  Anyone?  Is it worth trying? What are the benefits/liabilities of grid-leak bias?