Audio Equipment

[firedome]

860 kHz

WFBR maybe?

Tube manuals: still have tons of 'em, RCA, Sylvania, GE, Philco, along with an RCA tube caddy full to the brim.

 

[tolivac]

Firedome you helpted me remember the Baltimore places Roger and I contracted at.Was sort of fun--WCBM was indeeed oldies-their oldies library was stored in their station generator room-racks and shelves full of records,reel tapes,and carts.Bet that stuff would be so valeable.Worked with them when they were running the news format.Their two RCA 10U transmitters were so beautiful!!!!Loved working on them.These had enhanced power supplies and with the old Kahn "Symetra-Peak" audio processors you could run them to even mr James Marshall would approve LOUD&CLEAN-100 % neg mod and 200% positive-despite this was loud and so clean.Made table radios stand out.The RF PA had cathode resonaters for better efficieny-the stage could use 2 5762 tubes instead of 3 as in RCA 10H transmitters.The modulators were 3CX3000A7-higher audio gain than 5762.
WFBR had 1Kw transmitters at the time Gates 1G and 1F.later than went to 2.5Kw--Harris SX 2.5-solid state transmitter.WBAL was 50Kw-they had a really PRETTY RCA 50Kw Ampliphase rig built in the 60's pretty midnight blue cabinets-chrome framed glass tube veiw windows-and to top it off a blue panel above the transmitter cabinets with RCA AMPLIPHASE spelled out in large chrome letters-so beautiful!And with the tubes going even prettier!lets see-4-250 glass first RF,than 4CX5000 drivers,then 6697 finals.They had a Continental 317 still in its shipping crate-offered to install it for them since I just installed one at WPGCAM.WBAL already had someone arranged to install their 317-DARN!
Good you still have tube manuals-I have a lot around,too.Used to buy them anytimne I saw one at a used bookstore.Us tube guys have to have and use our FIREBOTTLES!!!!HOT GLASS!!!

 

[tolivac]

The Oswald Mill Audio site is interesting.The Garrard and Thorens TT's he mounts on the slate bases-sometimes those were encountered at smaller radio stations.The SP10's were most often used in production studios-not for typical airplay-in fact during the later 60's onward-most stations were "carting" their records-the records were recorded onto an endless loop tape cartridge something like an 8-track.The broadcast cart ran at higher speed-the pinch roller was in the cart machine not in the cart as in 8-tracks.The cart had two "Q" tracks-one for stopping the cart after the cut played,another -aux Q track to be used for other purposes-turn on a light when a cut is about to finish or start another cart or event.The carts were first used for commercials.Radio jocks liked handling the carts over records.Direct drive TT's such as Technics were often victims of the jock coffee or soda spill-this would cuase the TT to no longer turn.I have fixed these by taking the table completely apart-washing the boards in water and alcohol.then let them dry completly-putting it back together-then the TT was fine--ready for the next spill?Idler drive TT's QRK-Russco would suffer when DJ's would leave the table "in gear"the speed lever set on 33 or 45.This would leave a flat in the idler wheel-most of the time could be fixed by running the TT at 78 for several minutes.Otherwise the idler would be replaced common part at many radio stations at one time.Leave notes on the TT's to keep the speed lever in "neutral" the neutral notch in between the speed ones.This declutched the idler wheel.
Can agree with the Oswald site on horns-they do give high efficiency-cinemas still use 'em today.And the horn can "force" sound thru perf projection screens better than unhorned speakers.The older WE horn were made from plaster-so they could break if not handled properly or carefully.The Japanese really like Altec VOTTS-Voice Of The Theater systems-Altec still makes 'em not for cinemas but for to import to Japan for Hi-Fi.Iam sure cinema suppliers now have a good stock of VOTT's retired when cinemas went digital-So VOTT fans may be able to get some that way-just keep in mind the unit will be flat black in color-so it won't reflect light projected on a screen when it was used in the theater.And like the "Monarch" speaker shown on that OMA site the wings used in between "bass bins" on the VOTTS to focus the bass.Usually those wings were heavy particle board or plywood.-and painted flat black.Can agree-that OSWALD stuff is pretty neat-807-aanother workhorse tube-we use 'em here in our Continental transmitters-as a first stage RF tube and as modulator drivers.In those transmitters 845 tubes are used as modulators.They impose audio on the power amp tube grid bias supplies thru a special dual secondary mod transformer.Cathode follower primary from 4 845 cathode follower 845.

 

[firedome]

807s

are basically a 6L6 with a plate cap, Heathkit and others used 'em in early post WWII Williamson type amps as they were common as dirt as surplus, I was kind of amused when I saw OMA using them as their latest "discovery" for their audiophile amps... used to have at least 10 NOS RCAs in boxes for a future project but sold 'em of a few years ago figuring it was one more thing I'd never get to.

The OMA speakers are quite amazing, but one would need to sell their house to buy them... you'd have the best sounding tent around, though!

We've been big fans of the Altec VOTTS for a long time, we had the "home" version Valencia 846s here up to last year, the only difference is slightly smaller wife-approved walnut cabinets instead of the flat black MDF in the A5 and A7s, and the 800Hz aluminum sectoral horn is mounted inside the cabinet instead of on top. Amazing speakers, but they have to be played at top volume to be really appreciated, just too much for our 20' room, a social hall, or maybe Bill Gate's living room, would be more like it. Like K-horns, they are so efficient 2 watts will drive you our out of the house. They went to our son who has a really big playroom, along with HHScott tube power, and were replaced here by more appropriately sized-to-the-room JBL L36s, powered by a tube Sargent-Rayment EL84 basic stereo amp, and controlled by a Sargent-Rayment tube preamp, uncommon and very sweet units rarely seen today. Replaced all caps with Illinois (yellow) polypropylene caps, which seem to be the best suited for keeping the vintage sound. Sold off a Thorens and a Lenco some years back during the CD rage, but looking for a vinyl playing replacement, still have the old LPs.

 

[tolivac]

Yes,basically the 807 is an enhanced 6L6 tube-the plate connector on top was to reduce capacitance when the tube is to be used for amplifying RF.Their interelctrode cpacitance is slightly less than a 6L6-6L6 was designed primarly for audio,the 807 for RF applications.And the 807 can run at higher plate voltages than 6L6-the supply for the first RF stage in our CEMCO transmitter that uses an 807 is 1500V.6L6 would burn up at that voltage.The 807 tubes in the audio stages of the CEMCO's run at 1500V,3000V supply voltage-they are resistence coupled voltage amps-so the actual plate voltage is less.We have a stock of NOS RCA 807 tubes for the CEMCO's they work better than the "new" Chinese made ones.
On the Film-Tech cinema discussion site members on that site speak of powering VOTTs from the headphone jack of a transistor radio-fills the auditorium they say.Remember the Altc Valencia-wanted some so bad-but they were too big for my apartment.The neighbors-probably wouldn't appreciate them unless I could play music they like.
It would be neat to listen to the OMA speakers-but speaker listening can be dangerous to the wallet-YOU MAY LIKE THEM!Then is when your ears are bigger than your pocketbook!

 

[firedome]

Luckily...

by the time you hit the mid-60s, hearing has so deteriorated that you can't hear the difference!

 

[ovrphil]

..or like Pete Townshend, you're lucky to hear at all ...with hearing aids.