Products covered, with text, some specs, and photos, include: Brush Magnetic tape recorders BK414, 710B, 810, and 808 Twin-trak; hi-fi tube amps from Brooks (10C3, 12A3), Meissner 9-1093 tuner amp and 9-1091C, RJ-12A tuners; tuners from Browning, Many Stephens Tru-sonic speaker systems and drivers including P-63HF, P-52A, P-52LX, P-52HF; Hi fi amps including Scott 210-A, Fisher SA-1, Altec Lansing 323B, Newcomb HLP-14A, Bogen PX-15, Thordarson 31W10AX; Bell 2122, Masco MA-12EZand Rauland 1825; FM tuners from Espey, Meissner, Craftsmen, Howard; Customode hi-fi furniture and cabinetry; Altec drivers including the 603B, 600B, 400B; Jensen drivers incl. JRP40, HNP-51, JAP-60; Cinaudagraph speakers CIN-12A, 15B, 15C; and so, so, so much more.
Apologies for the poor image quiality; these came from the research department of a long-gone British broadcast-gear-manufacturer via some dampish papers that I purchased recently from a rare-books-dealer in London. I had never heard of the Fairchild 627 ‘Variable Equalizer,’ even though I recently sold an example of its (even-more-rare) predecessor the model 540, which in retrospect seems to be the ‘boost’ sections of the 627 plus a mic preamp plus a 20-watt cutter-head power amp. Well shit. Now i wish I had measured the values of the triple-ganged frequency-select pots. Why? We will get to that in a minute.
A quick google search suggests that there are thought to be only 5 Fairchild 627 equalizers in existence. One seems to have sold on eBay recently in the $7000 region. The 627 is a line-level EQ with continuously variable low and high bell boost sections as well as high and low roll offs. Unlike a Pultec, though, it is an active EQ, and it uses some pretty unusual circuitry – especially the high-cut section, which I don’t comprehend at all.
One point to note: T2 should be wired to reverse phase. I was v excited to find this schematic, because it seems like a pretty easy piece to build – there is no mention of the proper B+ voltage, but 250 is generally a safe bet; there are no weird inductors (the UTC S-23 plate-load choke is an off-the shelf part, so we know its specs -5000ohm DC, 300 henries); the audio transformers don’t need to handle DC and the turns ratios are spec’d: BUT: But. Those triple-ganged pots. WTF do we do about them?
Can anyone crack this case? Any insights, pls let us know in the comments section.
On the plus-side: at very minimum, this schematic does reveal an excellent and easy way to implement a 6E5 seeing-eye tube simply paralleled to a grid in the audio path. So at very least, now i know how to use those v excellent things in my mic preamps. Way more evil than a VU meter.
Also: the 6SN7 output section is a neat little self-contained module; def worth trying it with a Hammond 156C choke and an Edcor 15K:600 1/2 watt. The 156C is the closest modern part to the S23 spec; it is rated 150h and 3.7K ohm, seems close enough? I used onna these on a hunch in my OP6-semi-clone and it worked just fine in that application, so I am guessing it may work fine here as well.
Yes it’s that time again: Open Studios at the American Fabrics Artists’ space in historic Bridgeport CT. As per usual we will be offering our annual TAG SALE event. Much rad audio / recording /musical stuff for sale at well below typical online / ebay prices. Used and vintage hi fi gear, rack equipment, vintage microphones, NOS audio tubes, transformers, blah di d blah blah blah
Our ongoing series of cassette multi-track experiments rolls on with the Sansui MR6.
This ADAT-sized multitrack machine dates from 1990 or thereabouts. It records 6 tracks on a standard type 2 audio tape at double speed, with defeatable Dolby C and zero return. And that’s pretty much it. No gain trims, no autolocate, nothing. It really is strictly a tape machine and requires a mixer in order to use it in any sensible way. I picked it up for about $100 on ebay; a quick clean and demag and that’s it. Seems to work fine. High end response seems to trail off around 14k on a first-pass, which is A O K w/me. Here’s how it sounds, and thank u Jenny Holzer:
As with the earlier tracks in this series: the rules for tracking and bouncing are simple: no midi. no editing. Nothing u couldn”t do in the 80s. The only effects used for tracking are the Yamaha E1010 that you see there, a cheap boss reverb pedal, console EQ, and acoustic sources were tracked with some compression via that Symetrix 528E you see there. Marimba and shaker/tambo were mic’d with a Neumann KM184; vocals are an EV RE15 for no other reason that it is what I had on the desk at the moment.
1: Korg volca beats kk/snare pulse sync’d to korg SQ1 driving that repeating 8-note figure on… 2: korg MS20, 3: one-note low pad on Minbrute, 4. Yamaha MR10 toms/CH SN dbl hand-played, 5. elec bass DI’d thru a cheap gtr preamp
(bounce to track 6)
8th note shaker/tambo played w foot, 2. Marimba (doubling and/or harmonizing MS20 part, 3. Basic polyphonic sampler of me singing an ‘A’ note ahhh, 4. analog choir synth sound
(bounce to track 5)
1, 2, 4: vocals (hi is doubled),
3: ch synth pad
My goal as with the previous productions was to mix this all on my lil Mackie Onyx 1220 el cheapo mixer into a single pair in Pro Tools, but I couldn’t find a way to route it while still using two FX returns (my patchbay on this lil desktop rig is very limited). So I played all six final tape tracks into P/T, and once in PT it was hard to resist applying a bit of EQ and compression to each stem. Also mix FX on vocals were via P/T (Echo Boy and Valhalla Verb). But that was it – no editing, no tuning, no fixin’. That weird noise at the head is probably some kinda bias abomination that resulted when I did the first bounce, but it’s really part of the charm, ain’t it. Whole mix is low passed at about 12K, which really ties it together IMO.