Stephens Tru-Sonic 15" woofers in Ampex Signature

[CoastinHome]

@matt e.

The 1960 date for revising the dual woofers to single 15 inch woofers make sense from all of the information I have compiled.

By at least early 1959 all Signatures seem to have been delivered with ElectroVoice T35B horn tweeters. It looks like the first revision to single woofers was to Stephens 15FR + 8FR midrange -- and later to Altec + Ampex by ElectroVoice drivers (Altec 803B woofer; EV SP8B variant midrange).

The evolution of the various drivers prior to that time is more of a mystery. Those with a pair of 12 inch woofers had either a JBL D260 variant by/for Ampex (with the two felt dots adhered to the dust cap) or an Ampex midrange like the one below (felt dust cap - often marked with an "X"). Most seem to have the EV T35 tweeter... But apparently not all.

Here's yet another variation (pictures grabbed from an old thread on audio asylum):

12" and 10" drivers (according to the person who posted these photos). The drivers both look like 12" to me...Looking at the horizontal location of the centerline mounting screws.


No mesh or cotton candy. A "4-way" crossover according to the person who posted these pictures. Certainly it is a more elaborate crossover -- but it does appear that the woofers are in parallel so it is unlikely to be a four-way crossover but rather is to provide sharper slopes for the tweeter and midrange. The woofers are in series on other units - This crossover seems to have large power resistors to control the series impedance. A lot of mysteries to these consoles!


Unknown tweeter

 

[matt e.]

Wow, thanks for the schematic post and info on the feedback loop. Just got back from the estate a little while ago. Haven't unloaded the truck yet and will be making another trip tomorrow to get the cabinet and speakers. I uploaded pics and apologize for the poor quality. Packed up everything I thought I would need and discovered I forgot my reading glasses so focusing was a problem today . Pulled the front grill off after removing the doors and mine has 2) 12" woofers, 1) 8" mid and 1)tweeter. Have not opened the speaker backs yet, but assume they are like the picture from the guy who thinks they are 4 way. The amps had not been connected in a number of years. Line cord crumbling brittle, output tubes combination of Great Britain, Holland and one Amperex bugle boy.....no idea of condition. One amp had a small 4 pin connector fastened with wiring that seems to disappear under the cabinet....maybe an aux pilot light? Someone had disconnected some of the speaker wiring and it was dangling out the back like they had used the speakers with a different amp at some time. Peg board back doesn't look original. There are no missing knobs....I pulled them yesterday morning when I bought this to make sure they didn't walk before I got back to pick it up.

http://indoorphin.com/radio/ampex/estate_pics/

Any idea of production numbers or how many have survived?

Matt

 

[matt e.]

Serial No. 1025 Model 8002

 

[CoastinHome]

I've been outside all day in the hot San Diego sun working on a challenging roof repair before it rains in a few hours. Yet the project doesn't seem so difficult when I think about the challenge of moving an Ampex Signature down a set of stairs to a basement. You can only lighten the load so much.

When I moved mine I cut a piece of plywood the same dimensions as the base of the Signature cabinet and bolted on a set of very large inflatable-tire casters at the four corners to help me get over the edge of the porch, door thresholds, etc. The plywood really just holds the wheels in place... It didn't have to be rigid. Stairs is another deal. Remove the casters, lay down a carpet runner.. and let her slide? You probably won't regret getting out your video camera to document how it got to its permanent home!

Gradually figuring out the thing with model numbers. Haven't even gotten to the serial numbers yet. But here's the tag for a model 8002 sold in April 1959. It bears serial number 21124 -- so it doesn't seem like the serial number reflects only consecutive unit numbers. Another mystery to be unraveled.



Don't know why this invoice shows a different serial number... But the owner posted this invoice with the rest of his pictures when he was advertising the intact and original console which this tag is attached to. The features of the unit are consistent with this sales date -- and a label on the back of the unit does indicate that it came from Penny Owsley Music Company.



Anxious to see some pictures!

 

[CoastinHome]

Just noticed your pictures... Great job on capturing the details!

The unit is built very similarly to the above 8002. The differences I notice at a glance are:

1. The speakers with the dome tweeter. Didn't expect to see another of these the same day I posted the other pictures. This would have to be an earlier manufacturing date than the one above.

2. Rather than hanging brackets from the underside of the top surface to hold the tuner and preamp, this one has laminated blocks of wood attached to the sides of the cabinet to serve the same function.I haven't seen one like this before.

3. The pegboard on the back looks like someone's retrofit. The back is supposed to have cutouts for breathing. I can send some pictures at another time. I'll bet those amps were running pretty hot!

 

[Omegaman]

Thank you. A lot of good pictures there

Your console simple has twin blocks of wood that the pre-amp and tuner connect to.
I could do that

 

[matt e.]

Sunny San Diego sure sounds nice. Overcast with a chance of snow Sunday here. Yes to everything you said about moving this thing. My basement stairs are carpeted so yes it can slide. There are no casters on it, but I have not looked at the bottom yet. Actually I'm in the middle of a major remodel and hope to put my house for sale next year....if I can pull myself away from the estate sales. Getting this thing back up the stairs will be the problem. I may need to mount a winch. I'm trying to convince my wife it would look great in her office so I can avoid the whole stair thing....yes she knows. I think it is probably a '58 production. BTW, that is really weird that they would have changed that manual and not bothered to indicate a revision. I scanned paperwork included into a pdf. Warranty card was never filled out & returned. Looks like it has data programming holes....??? There was a free offer for tapes form that was also never submitted. Per the owners manual I posted yesterday two microphones were also included originally. I'm assuming that explains the unfilled EV warranty card. Two service repair tickets from possibly the original owner dated 1967. Garrard manual also included. Unrelated, but found with same documents included an Ampex 600 (1954) operators guide and a 1961 Webcor brochure. I would guess this was not the original owners first experience with tape recorders.

Do you recognize the microphones shown in the owners manual?

Also I found this blurb in the Nov '59 issue of HiFi Review. I looked around the estate to see if anything related might be there and came up empty. I think my unit was before the personalized leather manual. For $2600 you deserved personal attention. This thing reminds me of some of the 30's E. H. Scott radios. Relatively it's in the same league of Rolls Royce quality. Lucky to have spotted it at the sale. I was the only one in line who wanted it.

 

[matt e.]

Thank you. A lot of good pictures there

Your console simple has twin blocks of wood that the pre-amp and tuner connect to.
I could do that

I can measure the blocks and distance between if that helps.

 

[CoastinHome]

Matt,

Re: <<Per the owners manual I posted yesterday two microphones were also included originally. I'm assuming that explains the unfilled EV warranty card. … Do you recognize the microphones shown in the owners manual?>>

My 1961 Model 8202-2 came with a pair of original microphones and bases just as shown in the 1958 user manual.



The mics were were manufactured by ElectroVoice and sold under license to Ampex Corporation as the H-1390 starting in the early 1950's until being discontinued in early 1960's. (The H-1390 is actually a first generation ElectroVoice 636 dynamic microphone.) The 636 was in production for almost 20 years, ending as the second generation 636 in the late 1960s.

Those were likely the warranty cards for them in your collection -- I've seen the same pair of cards with a 1961 console.



The 636 / H-1390 are dual-impedance microphones which can be configured for high impedance or low impedance depending on how the cable is wired. They would have been wired for high impedance to use with the Signature. As you can see in the pictures, these were supplied with ElectroVoice Model 418 cast bases.



For reasons unknown the H-1390's that came with my Signature look unused but have the cords cut off flush inside their bases. It’s almost as if they were wired, tested and then the cords removed at the factory… leaving the choice and responsibility to the customer as to how to wire them. Hard to imagine that …but just as hard to imagine that any owner would have reason to unscrew the strain relief/water seal cap on the Amphenol connector and use a sharp pair of flush-cut nippers to neatly shear the cables inside the caps on both microphones. Another mystery.



ElectroVoice also sold these same microphones under license to other manufacturers. In addition to ElectroVoice and Ampex badging I’ve seen the 636 badged as a Stromberg Carlson. There is an example on the site linked below -- as well as some interesting details, the spec sheet, and a photo of Chuck Berry "reelin and a rocking" in front of one:

http://www.coutant.org/ev636/

THANKS for scanning your docs!... very interesting! (Especially the labor rate!)

 

[CoastinHome]

I'm trying to convince my wife it would look great in her office so I can avoid the whole stair thing....yes she knows.

Sell her on how toasty it will make her office!

 

[Omegaman]

Ampex "Modular" system 2018

The cabinet meets the hardware



Its a shame to hide those beautiful mono-block amplifiers


FM StereoTuner


Turntable


And Tape deck

 

[matt e.]

Thanks for the mike info. Now I know what to look for. Bought a refrigerator truck at HF this morning and it worked great. Wasn't too difficult at all getting it out of the estate house. Still in my truck awaiting decision on where to put it. One caster is missing and there is a crack in the baseboard that needs glue and clamping.

 

[Omegaman]

First time playing the speakers with the mono-blocks and pre-amp

Notice the LP playing

Oh yeah, made for each other

 

[matt e.]

Finally brought the cabinet into the house today. One caster and wood block mount is missing. Another has a cracked through wood block and another has a substantially bent stem. I might as well replace all the casters and make new mounting blocks. The original caster wheels are only 1 1/4" dia. Not sure what I'm going to use, but leaning toward either ball casters or the kind that have a plate and screw on with four screws instead of a stem. Is there anything behind the long panel on the bottom that fastens to the two center stretchers? Mine has several extra holes in it for some reason like it's been off before. Maybe they stashed their loot in there. I'm going to open it just to see if anything is in there. Looked all over the cabinet for a date code, but no luck. A white "L" mark for the left amp and evidence of something written on one of the speaker baffles, but can't make it out. Haven't pulled the speaker backs off yet.

 

[CoastinHome]

@Omegaman

Nice work! You really get things done… Thanks for the pictures!

I was looking for a picture of the bottom of the cabinet to share with Matt E and had to notice that my cabinet has a GE47 bayonet base bulb as indicated in the parts list -- rather than the GE46 threaded bulb that you mentioned yours has.

 

[CoastinHome]

@matt e.

Wonder how your caster got bent that direction... Opposite the direction it would bend from downward force or the direction of force if hitting something while rolling. I wonder why I wonder about things like that.

Mine also had a bent caster and a missing caster as well as a cracked base. I ended up removing the cracked block with my electric plunge cutter / vibrating saw tool ($20 at Harbor Freight) and made a new one. I glued it in place with gorilla glue using the original screws.

I bought a set of very similar vintage casters on eBay. (I was happy to pay 20 times their original price!)


To address their loose fit in the worn holes in the wood blocks, I first greased the shafts of the casters so that glue couldn’t stick to them, snapped them back into their sleeve bearings then installed the sleeve bearings into the cabinet with some sparingly used (expansive) gorilla glue at the top of the sleeve. Rock solid.

If you’re going with other than very similar casters, pay attention to the offset of the caster. I initially bought slightly larger diameter casters that I thought would make it easier to move on the carpet, but neglected to consider that they had a greater offset -- and they didn’t quite clear they edges of the cabinet base when they rotated.

As far as that lower cover having been redrilled -- I'm curious whether it's actually a stack of plywood or lamination of plywood. Mine doesn't have any screws in the bottom face -- just a few staples. But it appears from the pictures that there are screws on the sides.That sure is a lot of weight to support at four corners -- and none of the cabinets seem to sag at all.

You mentioned that you had to keep yours a few inches off the floor -- at least if it ends up in the basement. The casters don't work very well on carpet and want to mark their territory if you leave the console away from the wall for a while. What would work better for carpet is to lose the casters and have it sit on a large slippery surface. I'd like to come up with an idea for a single piece of material that would serve that function. Several of those 8"x8" neoprene backed furniture glides are doing the job for now.

 

[matt e.]

Mine does have a 47 bulb, but the wiring goes from the right amp (looking from the back) over the back edge, then through the center stretcher thing and then to the front lamp holder. It also has green grease on both solder lugs. Yours goes up through a hole in the bottom and then under the turntable drawer back to your amp. Maybe they changed that to prevent the wiring getting shorted and smashed where it crossed over the back edge?

Agreed about casters working on carpet. That's why I was considering using ball casters, but weight ratings are only for about 240 pounds per set of 4. You are also correct about the limited amount of swivel room. Weight ratings for all smallish casters seem very underrated for this thing. Maybe nylon glides are a better way to go?

The long center cover is just a piece of 1/4" plywood that is screwed to a couple of approx 1x4's on edge that stretch the length of the cabinet which are there I presume to keep things from sagging in the middle.

The wooden caster mount blocks are two pieces of 3/4 hardwood stacked and screwed on so I should be able to easily remove them and make new ones from a piece of poplar or maple. Obviously the casters hit something with enough force to break and bend them.

Another observation is how easily the Ampex logo on the preamp falls off. I pulled it out of the box, barely touched it and it fell right off. No big deal and will be easy enough to glue back on, but probably explains why some others I've seen online have missing logos.

 

[Leland47]

First time playing the speakers with the mono-blocks and pre-amp

View attachment 1305196
Oh yeah, made for each other

Beautiful! Looks great!
I didn't realize your pieces were the Silver Face....looking good.
Did you make all the gear cases earlier...pre cabinet purchase?

 

[Omegaman]

If you lay the console on its back or front, then lift the console upright, it will damage the casters from pressure and weight


Did you make all the gear cases earlier...pre cabinet purchase?
The hand made individual tolex covered cabinets were a project from the past. I was just lucky to find the cabinet
http://audiokarma.org/forums/index....-ed-component-reconstruction-complete.712047/

http://audiokarma.org/forums/index.php?threads/ampex-tube-pre-amp-case.624137/

http://audiokarma.org/forums/index.php?threads/help-id-vintage-speaker-cabinets.504824/

 

[matt e.]

Yep that's probably what wrecked the casters. Ordered a set of these tonight. Rated at 100lbs each and still smallish. https://www.amazon.com/gp/product/B01N579G7Y

Great work on the tolex. Those are beautiful. Am going to have to order a couple yards from AES for a tube tester box and a guitar amp head that needs a case. Years ago I had a pair of Ampex 15watt 6973 amps. They sounded great, but I sold them to buy something else. It looks like you might have KT66's in yours. What monoblock version do you have?

I'm all out of space and wife's patience around here. No more consoles for me....or at least until something else goes first....or until the next great deal pops up. This 8002 will really be hard to top. It's a disease you know. Estate sales are funny. Nothing worth buying for a couple months and then all of a sudden within 2 weeks I stumble into a rare UTC MLF power amp, another Heathkit SP2 (with remote), a Heathkit PT1 with AC11, and a Heathkit tape deck TR-1AQ with a pair of AA-171's (one unbuilt in the box). The other hifi pickers around here must be sleeping. Sad part is it's more likely a generation of people passing away bringing more stuff to market.