Above: circa 1963 announcements for the Bauer model 920 “Peak Master” (appears to be a UREI model 175) and the Teletronix LA-2, which was at some point re-branded by UREI. I feel like I have seen these Bauer pieces on eBay from time to time, but the internet is silent regarding them. Anyone? Whats the story with this piece?
So I was flipping through Recording The Beatles recently and I was reminded that I had yet to make one of those famous EMI console preamps. As luck would have it, we were hit with a pretty major blizzard and I had a few days with nothing much to do. The preamp turned out great, I love the fast (fast for a tube/transformer circuit, that it…), assertive sound of it, and I will definitely be making more of these things. I’ve been using it primarily for tambourine (with a vintage Senn 409), acoustic slide guitar (with an Altec 660B), mandolin (with my Audio-Technica 813) and acoustic rhythm guitar and shakers (EV RE15).
Here are some of the resources that I used to build the device. I apologize to whoever originally posted these documents for my lack of attribution; I DL’d them so so long ago that I can’t recall where they came from.
DOWNLOAD: EMI-REDD47
Another Download: REDD47AmpSchem
And these two images:
There is a real lack of consistency among these documents, and no I am not going to offer a ‘corrected’ schematic; that being said, if you actually have the where-with-all to fabricate one of these things from scratch I think you will do just fine with the same materials that I started with. And if you don’t want to do it from scratch: no problem! Just visit these dudes. (n.b.: I have never used a drip electronics product personally, so I can’t vouch for them; that being said, they are extremely popular and seem to know what they are doing).
A few build notes
I used my usual Jensen input transformer (click to DL info) and Edcor output transformer. The thing sounds great overall, so I recommend these, at least for a first-build of this circuit. Why spend more?
Very important: this circuit uses a lot of negative feedback. There are also a lot of capacitors in the feedback path. Each capacitor contributes some hi-pass filtering, which should be below audio range, BUT… if the capacitor values don’t all ‘play -nice,’ you could end up with so much phase-shift in the sub-audio region that there is 180-degree phase shift in the sub-audio region and you will have a device that ‘motorboats,’ I.E., your ‘negative feedback loop’ is a POSITIVE feedback loop aka a fkkn oscillator. I had this problem initially. The device worked fine, seemed to sound good, but at the lowest gain setting (aka the setting with the MOST negative feeback, get it????) I was seeing some 10hz signal pretty prominently in the audio files. I guessed that this was due to the fact that I used a 47uf cap by the cathode of the input tube, rather that 100uf that is specified. I made the correction and viola problem solved. HERE’S THE SHORT VERSION: with this much feedback, component values are critical. BTW, who knew that Apogee A/D convertors work so well at 10hz???
The Redd 46 has a three position gain-switch, and also a ‘gain trim’ control that does very very little. Think of it as a ‘channel matching control’ rather than a level control.
Because of the lack of gain control, and the fairly high minimum gain setting, the Redd 46 really needs pads to be used in the studio. Since I did not leave enough panel room to add i/o pads, I have been using it with some external 10 and 20 db ‘XLR barrel’ pads. Depending on the amount of drive and crunch that I want in the signal, I have been adding the pad either before or after the preamp (or both!) before the signal hits the convertor. Therefore, the next time I build one of these, I am going to include two two 3-way (0-10-20) switched pads in the device, one before the input trans and the other after the output trans. I highly reco that you do the same. I generally use a pad design similar to this one suggested by JLM audio; never had a problem with it.
Above: another shot of my REDD 47; the box on the right is the power supply; basic voltage-doubler (ala the Altec 1566) with tons of filtering and a choke for the B+ and DC filament supply. Connection is by a 4-pin amphenol.
I have gotten a lot of questions regarding the enclosure used for the audio chassis: it’s a BUDD enclosure of some type, I can’t recall the exact product name; it was dead-stock from a local distro, last one they had, and I am guessing that it was manufactured in the 70s. No idea where to get more of them. If you know, please drop us a line…
Above: RCA 77, BK1, BK5, and a slew of others, all referred to by their ‘alternate’ MA-designations: the MA-2311, 2313, 2314, 2315, 2316, 2317, 2318, and 2319. Can someone tell us why RCA used standard model names, MA designations, and MI designations? Was it so they could charge certain customers more money for the same products?
Oh and let’s not forget the SK–designations. Anyway, here’s the SAME products in the SAME publication one year later. Confusing.
So true. What more DO you need in a mic? The RCA BK-5 is one of my all-time favs. No other ribbon mic sounds remotely like it. If you dig ribbon mics, save up for one of these. You will not be disappointed. Especially if you need to tame a sibilant vocal while retaining an overall ‘bright’ and forward sound. Also killer on piano, guitar amps, and probably everything else, actually…
From B.E. mag sometime in ’65 comes this article by one John Harmer. Nothing all that notable in here except to marvel as just how incredibly primitive the techniques discussed are. For instance, above… an explanation (and this is in a fairly technical broadcast-engineering magazine, btw, not a consumer-facing publication) of… an echo send! Hey everything had to start sometime, right? Also, there is much music from 1965 that still sounds fkkn incredible today, so there’s no reason to accept a ‘linear-progressive’ narrative of technology, is there…
CLICK HERE TO DOWNLOAD THE ARTICLE: AudioMastering_1965
How are y’all doing on this fine day… Wanted to LYK that I recently wrote another software review for our friends at ProductionHUB dot com… you can read the full piece by clicking this link. The review is for a new(ish) sample/loop collection called ‘What It Is,’ and it’s a library that I have found useful+ enjoyed working with lately. As I have often remarked on this website… my interest in all the ye olde audio stuff is not academic or collector-ish in nature… I actually use this stuff all the time in my work, be it studio sessions with bands or television/film music. Loop libraries often a part of the latter, and it’s a product category that I have been exploring for many many years now. You might imagine, therefore, that my interest in a 70s’-themed loop library would be especially strong. And you would be correct. If any of you, my dear readers, also use these types of products, drop us a line with any recos that you have to share.
For my previous ProductionHUB review, click here.
Today: just a round-up of some broadcast mics that caught my eye for some or another reason: above, the ‘Stanford-Omega’ condenser mic. This is an odd one. Anyone?
EV (electrovoice) 666. I think I have mentioned this one about a million times already: it’s the predecessor to the RE-20, a mic that I have used+ dig more than almost any other. EV 666’s appear in just a ton of great-sounding old TV music-broadcasts… Miles Davis on PBS comes to mind… I must have bid on these things on eBay about 20 times. No luck yet. Soon enough. Oh but BTW I finally did get an RE15 (and not cheap either…) and it is really, really underwhelming. Still my faith persists…
Sony TELEMIKE circa 1964, with an (up-to) seven-foot probe! And it comes with a built-in headphone amp. Wild…
AKG D-12 and C-60 circa 1963, a few years before the D-12 became the industry-standard in kick-drum mic’ing. AKG recently sent me one of their new D-12 ‘VR’ models to review, and it’s pretty great, although not a re-issue in any strict sense… full review to come soon.
And finally the EV 655, another favorite of mine… just great sounding omni mics, pretty incredible fidelity for units that were introduced in 1951. Lots more on this site about them.
Courtesy of Kodak, a discussion of the problem of print-thru on audio-masters. I used to notice this on LPs quite a bit as a kid, Led Zep esp. comes to mind, and I always assumed that it was intentional… kinda just makes the whole thing seem more EVIL, ya know? But apparently not. Apparently this was a thing-to-be-avoided. Hey any of y’all ever create an artificial print-thru ‘effect’ for a DAW production? Drop us a line and let us know… seems like it could be interesting,,, anyway here’s the bit:
Above, Shure’s SE-1 RIAA phono pre. I would love to see the schematic for this is anyone can direct me to it. The specs look extremely good. These seem to go for a pretty penny on eBay and seems like a worthwhile thing to DIY. Anyone?
And above, again, this time next to Shure’s 576, 570, 546 (AKA SM-56) and 333 mics. I have the ‘other’ broadcast – quality Shure Ribbon, the 300, and I like it alright… had it re-ribboned by Stephen Sank and it’s decent. The 300 definitely sounds v v vintage but it’s a useable sound. Really want a 333. This is the same as an SM-33, yes? No? anyone using these things lately?
I spent a good portion of the fall last year working on Stephen Kellogg’s new record BLUNDERSTONE ROOKERY at Gold Coast Recorders. Stephen produced the album with Kit Karlson; I engineered, and the mixing was done by Mike Mogis at his spot in Omaha. Audio mastering by Bob Ludwig at Gateway.
As USA TODAY announced in this great write-up last month, the album drops June 18, but Stephen decided to pre-release the 10-minute track “Thanksgiving” with a wonderful music video by Daniel Cummings. Beyond the length of the song and the emotional intensity of the lyric+vocal performance by Stephen, this production is incredibly epic in scale: from the full live choir that bookends the body of the song (recorded on-location in Massachusetts) to the kaleidoscopic arrangement of live rock band, horn section, and big string section, I can safely say that this track is the most ambitions that I have been a part of. We’ll have a more detailed account of the album sessions when the album comes out, but for now, check out… “THANKSGIVING.”
How are y’all doing… I recently picked up a large pile of the old ‘Broadcast Engineering’ mags from the mid 60’s. Although much of the content focuses on video engineering (not quite ready to go there yet…), I found a good amount of audio-related content that is still potentially relevant today. I’ll be uploading bits and bobs throughout March. Thanks for reading, and stay tuned…. oh and here’s a sample of that yr in for…
