Building a dedicated mono system for 78s.

Hello all,
With my main stereo system finally more or less the way I like it, I've decided to construct a mono system for my 78s... but with a twist. I'm basically limiting myself to vintage equipment (or clones of said equipment) that was commercially available prior to June or July of 1947, when the first floor of my house last underwent a major remodelling.

Amplification is all set up; I built a clone of the Brook 30 watter (model 10D IIRC). It wasn't a cheap build (about $1k before tubes, not including my blood, sweat, and tears), but then neither are the originals (pairs fetch $12k or so). I built a mono all-octal phono pre as well; one of Thomas Mayer's designs. This was less costly than an original Brook preamp and likely better performing; the Brook design can feed 300 VDC, well filtered, at 90 mA or so, plus 6.3 VAC for the heaters at 5 or 6 amps. Way more than enough for the preamp circuit...

I have an adequate period correct changer restored and a GE RPX mounted.

The only major piece I'm missing is the speaker. I need a single speaker from that era, ideally something that will reproduce 50 Hz to 15 kHz or so with ease, and won't fry with 30 watts input.

I was thinking about trying to track down an Altec 603 or the early field coil 601. Any other, perhaps better, speaker recommendations?

Comments in general?

 

Good luck and have fun. 78s can sound amazing. What kind of music are you going to play on it?

 

Big band and blues records comprise the bulk of my 78 collection. There are some excellent classical recordings on 78 too, despite the enormous limitations inherent in shellac.

 

First of all, I have absolutely no opinion or comment to contribute to your question about speakers. However, congrats on the 78 system--you will have a ball.
I went about things a bit differently: Added a dedicated mono/78 table (restored Dual 1229) and tube phono stage to the existing system. I like the idea of going the vintage (or vintage-esque) route. Good luck and report back.

 

That would be asking an AWFUL lot from a single speaker. You might get up to 6,000 Hz if you're lucky from one cone. A speaker SYSTEM is a whole other ball of wax. There, you'd probably be looking for something like a Western Electric theatre system. Here is a very good place to find information on historic sound. Antique Radio Forums • View forum - Antique Radio Discussions Yes, I've been into antique radio for years. Good luck! Keep us posted!

 

@drh

 

You're not going to find much new today in a single speaker, as speaker drivers are designed largely to be part of a 2 or 3 way system, or if full range, are 3" drivers to be used in arrays of dozens or in a TV sound bar. 12" Jensens with whizzer cones for your furniture-grade cabinet aren't around any more.

Not from that era, but as close as one might get these days with modern standards, here's a Markaudio Alpair-10M Gold 6":





Seems like it can do everything on a 78 just fine with even a bit of "loudness curve" built in; in fact it might be too revealing of the surface noise of 78s. You might later regret getting just one.

Speaker builder using their drivers: Brines Acoustics


Or if you need a $2000 box for your $90 speaker driver:

 

Restoring 78's for CD release is how I make my living. Not too long ago I did Brahms, Sibelius, and Roussel by the NBC Symphony Orchestra on Red Seal (which I never really cared much for).

 

That won't image correctly until you align it to the pole star.

 

You, sir, RULE.

 

My 15TRXs manage, granted it's a coaxial with a tweeter mounted in the middle, but it does make it clear out to 15 kHz.

I should have been clearer; a single speaker system from approx. 1947.

I'm over at ARF too. Not much of a radio guy though; vintage TV is more my style. I need a mono 78 system worthy of being in the same room as the 20 inch DuMont.

 

My taste is a little more Euro; Furtwangler mainly.

 

Hello, and if I may say so, what an exciting project! If you are looking to "recreate" a phonograph setup of the period, for what it's worth let me pass on what B.H. Haggin, an influential writer on recorded music, had to say about speakers in his Music on Records (the 1943 edition):

"The large machines that give this desirable sound have, among other things, good speakers in large, solid cabinets; and the maximum efficiency of the speaker--which means astonishing spaciousness and clarity of definition in the reproduced sound--is achieved by removing it from the rest of the machine and putting it into a separate cabinet of the infinite baffle type (not the bass-reflex type, which should be avoided). This is a simple box of 3/4-inch wood, of any dimensions that give the interior a minimum capacity of 15,000 cubic inches for a 12-inch speaker, 18,000 for a 15-inch, with a removable back that fits in flush with the sides, top and bottom, with long pieces of 1- x 2-inch wood fastened diagonally across the back and side panels to eliminate any vibration that is not prevented by the sold construction, and with the entire interior except the hole in the front panel for the speaker) lined with Kimsul acoustical wadding, 1-inch thick, of 2 1/2-pound density. A small hole is cut in the back for the speaker-cable to pass through; and for easy handling the box can be put on casters."

 

Oh, by the way, in hopes that it will be of some further help, here's what Haggin had to say about cartridges:

"At the other end the machine that gives the desirable sound I have described has a good pickup. This is something which the actual machine that you are likely to buy--no matter how expensive, no matter how good in other respects--probably does not have; and the sound from this machine will be amazingly improved by the substitution of a Brush PL-25 (or PL-20, which has a longer arm requiring more room). Since it is an extremely delicate and sensitive precision instrument it must be mounted and connected with the utmost accuracy in accordance with the Brush instructions, and must be handled with the utmost care to prevent its being dropped on a record or banged against the edge of the turntable--in addition to which it should not be used with records that are badly worn from playings by heavy pickups and steel needles. Though Brush says the jewel-point can be used for 5,000 playings, you would do best to stop at 1,000 (keep a record of the number of playings) and have a new point put into the cartridge. You should have Brush itself do this; and you can send back the entire pickup, or only the cartridge, which is easily removed and replaced. It is a good idea to have two cartridges, and to begin to use one whenever the other is sent back for a new point.

With the beautiful musical sound your fine machine will give you the sound of needle-scratch; and you will take both. For there is no way of eliminating scratch without eliminating the musical sounds of high vibration-frequencies that give present-day recorded sound its richness, brilliance and fidelity to instrumental tone-color. ...

You may, however, not want to accept the excessive noise, grit, crackling and sputtering from some present-day surfaces, the rattles and break-ups of the sound in some present-day recording. [Note: When he wrote these words, he probably had no idea what pressing horrors awaited as the World War II shellac shortages and limits on strategic materials hit home fully.--drh] For the records on which these occur--and for badly worn records--you may want an alternative pickup with a limited range that will conceal the defects; and the Astatic B-10 or Tru-tan is a good one of that kind.

... [Discussion of changeable needles omitted. A summary: Haggin recommends full or half tone Victor or Columbia steel needles, whichever gives best results for a given record, replacing the needle after each play. "If you can afford it" he prefers "shadowgraphed" needles and recommends the Actone RF-12A, "the one without coating, in the package on which the RF-12A is stamped in black," as less expensive than Victor's comparable product. He advises avoiding cactus, thorn, or "long playing" needles.]

Don't use a sapphire or any other jewel-point unless it is a permanent and integral part of a pickup--and then only a pickup as good as the Brush."

As an aside, "shadowgraphing" was an extra step of quality control, but it was a lot less sophisticated than the fancy name might suggest. It involved a strong light and lens contrived to project an enlarged shadow of each needle's point on a screen so a worker could see if it was properly formed.