An Intresting Find

[Frankenamp]

Found a strange variant on the Leslie rotating speaker genre. It reminds me in some ways of something you'd find in the JPL only much bigger and used to test astronauts. It has two 4" drivers mounted back to back and wired series (I think) and the wires co through a commutator of sorts to transfer the signal. I'm gonna have to see if I can transfer some of the assembly to wood or plastic. it uses something like .187"-.200" steel plate for the frame. Very Solid. I'm thing of crossing it at about 200 Hz and seeing what happens. I'll probably loose the variable inductor that is hooked to the pulley I'm sure it was in the path to the woofer to give a kinda 'chugging effect'. It was from a Baldwin Organ that the owner parted out. (Maybe I can get him st show me how to part out a Hammond M3...

Link to FleaBay Item: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250513115588&ssPageName=STRK:MEWNX:IT

Ever seen anything like it? May have to rig a single pole speed control of some sort...

[stingray_65]

very wierd I LIKE IT!

[Frankenamp]

Yeah, it's wierd alright! But, much more compact than a full-blown Leslie tone box. I've seen some guitarists use them to great effect. But the poor roadies must really "love" them!they must tip the scales at 200+ lbs. My midget will probably max out at maybe 40 lbs. Whats fun to watch is the guitar player wailing out a solo and using the headstock to work a Theremin at the same time (all run through the Leslie at whatever volume the enlisted club manager would allow).   

[stingray_65]

I was looking at tube screamers schemos the week i got my first leslie.

I can't get the thought out of my head of a 3" alnico i pulled from a TV and a tiny whirly gig and a condensor mic all in one small box and have a leslie pedal. hmmm I got an OLD astatic hiZ xtal elementand Ive built a few mono tube monoblock amps....
might be time to go small

[PRR]

> wires co through a commutator of sorts to transfer the signal. ... variable inductor that is hooked to the pulley I'm sure it was in the path to the woofer

Slip-rings, not commutator.

The coil is a solenoid to force a specific "park" position, so the non-vibrato sound is consistent between uses.

I don't see why you'd want to re-engineer it. Baldwin were not fools. It needs stiffness and some mass so that stray unbalance doesn't make it walk around. All it needs is a belt and a hi-passed signal.

[Frankenamp]

PRR: You're right- slip rings it is. My mental thesaurus went ex-stinked. I wonder if I really need a park position? (that means finding out the voltage of the solenoid)
The extent of my 'engineering' would be to put in some kind of wood case so it doesn't look like a refugee from Rube Goldberg's laboratory. It even came with some rubber shock mounts that are in decent condition. the motor's rubber mounts are starting to lean a bit, so I will have to rotate them about 180 to come back in line... or take a gander at McMaster-Carr's goodies or MSC (bigger book, more expensive), or maybe Grainger will be having another closeout... I'm gonna have Bay Seal sample me a buna belt out of some .187 or .200 stock, I'm not sure whether the original belt was a square profile ring or a simple bungee cord- I've seen 'em both ways. Just Spinning it with fingers feels smooth as butter, so I think I'll leave the counterbalance screw where it's been fer the last forty years or so. I'll have to meter it to see what the DCR is to get a ballpark value for the inductor.

Stingray: I see a few mutilated styrofoam cups and some mini motors in your future...

[stingray_65]

bought home a busted pump for the case tonight. the gear reduction was shot.

after gutting the case I was looking at the smalish motor. 90VDC and it had a speed controller too.

a bit of drilling and grinding on the motor plate of a leslie 2 speed and a trip to the hardware store for a $2.10 bushing to retrofit the pully and I grafted the DC motor onto a 2 speed plate. took out the trimpot on the pump speed control board and ran som leads to a Conn organ presence pedal and swapped in a 1 meg pot.

VIOLA! a variable speed leslie.

for a tiny motor this thing has TORQUE! No ramp up speed here!

not as small as I imagined LOL, but when parts fall into your lap you use them where they fit.

I haven't pumped sound into it with the variable speed controller, but when I had the unit on my bench testing it for funtionality it sounded great with that little ceramic Rola

I'm thinking I'll build a Champ to power it. I've got another pedal just like I used and wire up a nice length of beldon shielded wire and put the vilume conrol in a pedal too.

I'll have "inensity" and speed on pedals.

[6G6]

Interesting find.

Hey Frank, ya might wanna hold off on parting out an M3.
Those things are big, heavey and no fun to move,
but they ARE a top teir Hamond organ, very close to the famed B3.
They just don't make 'em like that anymore and there is a use/demand
for them.

[Frankenamp]

Interesting find.

Hey Frank, ya might wanna hold off on parting out an M3.
Those things are big, heavy and no fun to move,
but they ARE a top teir Hammond organ, very close to the famed B3.
They just don't make 'em like that anymore and there is a use/demand
for them.

Jury is still out on it's fate... It is in fabulous condition, aside from the cord being a bit dodgy and the previous owner saying it recently stopped working... (could be related) However, the size is an issue (even though it will fit in the boot of a PT Cruizer with a little string to hold the lid down) and it is built like a brick sh*thouse, it is larger than most people are comfortable with. It should have been built in sections. (SWMBO is about to inherit a Yammie electric pinanno and I doubt she will want to share real estate...) It does have a nice Jensen P12Q and I'm looking at the interesting things to do with that built in swell pedal... but I'm not gonna go off half cocked. I'm gonna finish reading a few more books, and learn some more things before I violate that piece of thermonic engineering.


Stinger:  That looks like a brilliant piece of catch-as-catch-can engineering! Bet it will work a treat.

Now I gotta get back to the garage to create some order out of chaos (SWMBO is bringing in some more things )

Current projects are a couple of 6GW8 amps, and a Motorola record player (3 channel) loaded with 6BM8's. Should be easily convertable to line level inputs (might have to figure out how to defeat the RIAA curve).

[PRR]

> a Motorola record player ... Should be easily convertable to line level inputs (might have to figure out how to defeat the RIAA curve).

If it is ceramic (crystal, piezo) needle (NO magnet), then it does not have the steep EQ which you know from magnetic phono needles. A ceramic does the right thing.

Almost. Actually a ceramic should have a small rise 500Hz-2KHz, and a cut below 50Hz. But "correct" ceramic inputs are almost unknown. In many cases, the needle is allowed to resonate upper midrange, which gives a close-enough overall balance. And since the ideal error is +3dB/-3dB, and consumer phonos were all +/-10dB, "overall balance" is all you can expect.

Sometimes the high-boost is supplied in speakers: not hard to dope a cone for a good bright sound. If you feed a"flat" source to such a system, you may want to run the Treble down a bit.

This is assuming 6BQ5 or 6BM8 or similar.... 250V plate 6V heater. Systems which "must" have a power transformer. Things are VERY different when you find 50C5 and other high-volt heaters: these are Hot Ground and must be used with an isolation transformer before you stick a finger on the input jack "ground". I did turn a hot-chassis radio into a decent line monitor, but I had to stay off of concrete, away from water pipes, keep my source truly un-grounded.... I shudder to think how many deaths I risked.

[Frankenamp]

Thanks, PRR! That's good news. The SP 29-E is a self-contained stereo record player with one 12AX7, 4 6BM8's, and a 6CA4 rectifier tube. (just got past the Rectifier section and into the Amplifier section- volume #2) No schematic hidden inside though. There is a diagram with the tube locations, controls, and major components and connections. The amp has 3 channels- 2 single ended channels (L & R) and one PP (Bass) channel. The speakers are  a 5" mid, & 4" tweeter in each detachable 'wing' (hinges connect the speakers to the amp when connected to the chassis- or plugged in with 1/4" jacks if theyr'e spread apart) There's a single 8" woofer in the main chassis (Motorola 'Golden Voice' model with what looks to be a bout a 1" VC & a good ol' alnico magnet. I think I'll end up making a separate box for the woofer and the electronics and possibly look into using something like a Hi Vi 3" full range driver for the mid-hi's... that is if the effeciency isn't too bad- If it is, (85 dB is pretty piss poor efficiency) I might try adding a small tweeter to the 5" mid driver I can't believe that the 4" tweeter is worth squat.  I think this was one of the better record players though. The changer was the same kind as in the nicer console  stereos,  and the fit and finish was pretty decent. everything is clean and untouched by prying fingers (other than mine!) Everything was built into separate modules PS, AMP, KNOBS, and connected with Molex plugs. The chassis are copper plated except for the pot cub- assembly which is sandwiched between an anodized aluminum extrusion, and the shield which is chrome plated... pretty nice stuff.                                            

[PRR]

Just replace the phono needle with your RCA or iPod jacks.

Personally, I would stick with the original speakers, if not blown. Those old guys could make very nice-sounding systems when it was a top-line model like this. And with tubes, that was a trade-off between balance and Efficiency. New speaker designed from cheap power may be flatter but a lot softer, and less exciting.

I assume you don't plan to use this as a Reference Monitor for commercial record mixing.... as an entertainment system, it may be impressive as-is.

(You might replace the Eight with a car-sound Twelve in 2 cubic feet. (Or since they are sold as pairs, two 12" in 4CF.) Commercial recordings today have more/deeper bass than they did in the 1950s, and we have learned to expect that. A Twelve will go below 70Hz with sufficient efficiency. And of course it can never burn-up on that amp! Then the hot Eight can go in a tweed Champ or something. I bet it goes to 5KHz, and will have interesting cone-modes.)

[Frankenamp]

Ummm yeah, right... (suggesting I build another speaker is like waving a dime bag under a junkie's nose) I might have to go to Home Repo or the local lumber yard for some benderboard. Making a smaller box than the current Frankenspeaker (which now is sporting some sparkly grill cloth and a vintage Altec Biflex 12" driver) Sin (or Son) of Frankenspeaker- with the Moto 8" Golden Voice might be a nice rainy day project... might have to be a closed back one cube box. Old drivers have pretty stiff suspensions. If I wanted to get an 8" down to 50Hz nice and loud though, I'd just put it in a little seven foot horn (can be as small as an 18" cube when folded) I have a couple of 8" drivers in a 13' horn...    I wouldn't use it to mix anything, but I bet the origional drivers would kick the crap outta any stinkin schmoze or eye-pawed system. I'm with speakers like youse guys are with tubes- gotta be tweakin on sumthin... car sound 12 in 2 cubic feet naaaah but thanks    I will just need an adapter to hook up the 'pod, It came with RCA inputs jacks and a cable from the bottom of the phono.

(now I gotta read another chapter of Nooger & Neville)