Ampex Signature Console 1959-1961? - Production Variants?

[CoastinHome]

1961 Ampex Signature Promotional Photo

I’ve enjoyed Bryce's museum tour of his Ampex console collection for a few years now -- and with some patience and persistence I finally found a very nice intact Ampex Signature for restoration -- at a time that it finally fit the budget. In the interim I had been collecting all of the information, brochures, ads, photos etc. that I could find. My most recent finds are the September-November 1960 Sunset Magazine ads (will repost when I find an original magazine) and the 1961 Ampex Signature promotional photo set.

I will be happy to index and trade scans - and will otherwise gradually post those of manageable file size.

I'm hoping this posting will inspire a continuing discussion of production dates, serial numbers and production variants of the Ampex Signature console - as there are apparently many different configurations under far fewer model numbers. I will compile any provided photos and details into a spreadsheet and repost at some future date.

My "new" Signature ("8202-2" s/n 1094) was delivered to its Lake Balboa, Los Angeles owners on May 3, 1961. I received it with the original hand-signed manual and the original (perhaps unused) pair of microphones (with, for some reason, the cords cut at the base of the microphones). The console also has a protective glass top - I assume the addition of the owner. I wish I had taken the car to the truck scales before and after picking up this console. It will remain a mystery for now as to how much this beast actually weighs.

This console has the 40W EL-34 amplifiers (selenium rectifier) and the 403 preamplifier (though the outdated manual describes the 30W amplifiers and 402 preamplifier). I'm not sure if the owner's manual was ever updated as the features were revised -- perhaps with the scan that Bryce shared of the 40W amplifiers being provided as an insert to the manual. (I’m grateful that you posted it, Bryce, as I could not find it elsewhere.) I haven't been able to find a schematic for the 403 preamplifier.

Some schlocky work was done in 1968 by the authorized Los Angeles repair facility -- mismatched output tubes on both sides, amplifiers swapped left for right in spite of being clearly labeled, atrocious cable reharnessing, nearly shorted speaker terminals and some cross-threaded and missing screws. The surprising lack of pride in workmanship still stands out 50 years later but fortunately can be addressed and forgotten. The company is long out of business.

I will need to choose some electrolytics and coupler caps -- and am interested in any (budget) recommendations. A while back I read somewhere that there are some high-quality cost-effective Russian-manufactured coupling caps on the market which are highly recommended. I'm much more familiar with electrolytics - having replaced many over the years. (I'm an electronics engineer, btw.)

This 8202-2 console appears much as shown in the attached Ampex promotional photo, though with the dark gray variant of the 960 reel to reel rather than the 1250. Less noticeable in the photo is the six-door cabinet. Mine has the much more common three-door parquet inlay style cabinet. Until I finally saw one of the six-door cabinets (minus components) advertised on Craigslist, I assumed that the six door cabinet in the promotional photos was only a prototype.

During my search for Signatures I have encountered a couple of other units -- each at a time that I could not make the investment -- with each ultimately being parted out by the new owner. By the time I found this unit I had already resigned myself to building a custom vintage stereo from the first of these two empty cabinets, with existing similar quality components from my collection. I realized that without the speakers installed, the width of the cabinet openings for the speakers are each 19.25”W... perfect for installing rack mount rails. - The Signature cabinet is very well made and without the speakers can hold quite a bit of rack mount equipment. I really liked the Barzilay K61B - until I saw how much better the Signature cabinet is made.

There were apparently quite a variety of different driver configurations provided with over the roughly 1959-1961 production run. (Can this be confirmed?...I'm trying to put these on a timeline. I haven’t seen any reference to the Stephens Trusonics drivers being optional upgrades (such as the Garrard 301 was for a measly $50 extra) but the Stephens drivers seem to be a similar level of upgrade. Either that or Ampex was looking at cost cutting after initial production with the Trusonics.. My empty cabinet that originally housed the Trusonics (Model 8102 - s/n 1077 -- re the 2014 "Ampex Signature in Los Angeles" thread) was of 1959 production.

My 1961 8202-2 appears to have a pair of Altec 803B 15” bass drivers, the Ampex 668-0022 8” midrange drivers (the deep basket drivers with the metallic brown painted baskets) and the ElectroVoice T35-B horn tweeters. (I haven’t disassembled anything; this judgment comes from comparing the appearance of the cones to other driver sets sold on eBay etc.).

The LH tweeter sits on a plywood filler plate which causes the tweeter to be pointed off to the left. I would have assumed that filler plate just had not been seated properly in the faceplate inset -- until I recently saw a picture of another console built the same. I have no idea yet whether the RH tweeter also points outward -- as due to production variances the RH grille fits extremely snuggly and will require some further creativity to release the bullet latch and pull the grille without damage.

While waiting for this Signature to find me, I also came across a Signature speaker set which a craftsman clock builder had years ago salvaged from a Signature console and installed the drivers and faceplate with crossover in a set of custom cabinets of the same internal volume. This set of speakers uses a pair of Ampex 12” on each side, the 8” Ampex midranges (those with the “X” over the flat felt dust cover as opposed to the Ampex/JBL 8” midranges (D-216?) with the couple of small felt dots on the domed dust cover), and the T35-B tweeter. I don't know any more than that about their history, but the driver configuration seems to be the same as an early 1959 model 8002 s/n 024952 that I also ended up with the cabinet for.

Which brings me to a question…

The Signature speaker set in custom boxes with the dual Ampex 12” drivers has gauze mesh covers over the back of the drivers to keep the cabinet damping material away from the back of the driver cones. I am assuming that the Signature console cabinet was originally filled with substantial damping material.

I have seen photos on the of the same configuration with only a couple of square feet of the traditional yellow fiberglass stuffed inside of the box (and without the cloth mesh over the back of the drivers). The configuration was otherwise the same other than the use of a dome tweeter versus the T35-B. (see photo)

The Signature cabinet which originally had the Stephens Trusonics before it was parted it out still had the remnants of the same gauze to protect the back of the driver. The speaker enclosures on this unit were packed with a surprisingly heavy mixture of white fiberglass or cotton (etc.) fiberfill mixed with something like sand (see photo). I still have the two heavy bags of that material that came with the empty Signature cabinet -- but am not sure if that material was unique to the use of the Ampex/Stephens 15” drivers or if it was used in some but not all of the dual 12" enclosures. Perhaps another cost-cutting revision along with the revision to the dome tweeter?

Q: Does anyone know if this dense acoustic dampening material is used in the dual 12” enclosure? Is it also used within the midrange sub-enclosure?

Thanks! ...Much to share yet.

Bob in San Diego

 

[Tinkerbelle]

Very nice unit there.

Bryce did share the 403 schematic in this post.

 

[CoastinHome]

Playboy Magazine - January 1961:



Thanks for the link, Tinkerbelle!

Very nice unit there.

Bryce did share the 403 schematic in this post.

 

[CoastinHome]

As Ampex evolved the 402 preamplifier to the 403, It appears that Ampex made use of their existing stock of 402 faceplates by bonding a thin overlay panel to cover and move the location of holes. It seems that the company kept the 403 Model designation even as the cosmetics were further revised.

The first photo is of a 1959 Model 402, photos 2-4 Are from two different units but represent an early Model 403, and the last is of a 1961 Model 403.

Are there any Ampex experts here that can confirm the timeline or know of any other cosmetic variations on the 402 and 403 preamps?

 

[byoungman1]

Just noticed that the date code on the transformer of the unit below is March, 1960...and parts sat for awhile before being shipped out and installed in equipment, so I assume this unit was built +/- 6 months after that.

 

[CoastinHome]

Thanks Bryce...We're making progress on the timeline!

Your photo must be the "early" 1961 version of the 404 preamp. My Signature which was delivered in May 1961 has this preamp with the 952 tape deck.

The Ampex promotional photo at the top of this thread (showing the different style knobs on the preamp, the rare six-door cabinet, and the late 1961 1250 deck) was shot on September 29, 1961. So that version of the 404 preamp must be the "later" version.

I have not seen anything on Ampex audio consoles that presents as a 1962 model -- other than the 510 and 520 retrofit FM multiplexers. Though cosmetically identical, it's entirely possible that the 510 never went into production -- perhaps because it was based upon a bet made on a different FM system before the Zenith standard was adopted.

 

[CoastinHome]

It seems that the company kept the 403 Model designation even as the cosmetics were further revised...{and}...The first photo is of a 1959 Model 402, photos 2-4 Are from two different units but represent an early Model 403, and the last is of a 1961 Model 403.

Since the original posting I have been able to establish that the brushed silver face models with the dark gray faceplate perimeter represent two different versions of the 1961 Model 404 preamp (with the differences for now presumed to be just the style of the knobs). I haven't established yet whether there are any changes to the circuitry from that of the 403 -- or if these are just cosmetic updates. Bryce is sending me a 403 schematic which I will use as a reference when going through the 404 and will share my findings.

Stay tuned for that.

 

[Leland47]

^^^^^^^
I wondered about the perimeter trim and knobs on that piece above. (beautiful by the way...) Thanks for clearing that up.

Here's a pic of the other style knob and face plate of one that recently sold....on that auction site.

 

[CoastinHome]

Here's a pic of the other style knob and face plate of one that recently sold....on that auction site.

Lee, I also saw that one advertised. The pictures from when it was first advertised include the broken faceplate perimeter frame. You can see it's been dropped on its lower right corner.

Below is a series of photos which make up a recognition guide of sorts for each "Audio Control Center" preamp option used in the Ampex consoles between late 1957 and late 1961. Will need to gather quite a few data points yet to get closer to which months and/or serial numbers are representative of when the changes were made -- but these are correct in terms of model year. My personal favorite is the 1960 403 -- but the 1961 models seem to be the general favorites.

The matching tuners are the Ampex-Fisher-80R-variant mounted in the same faceplate with the 401 in the 1957/1958 A423 -- and the 502, 503 and 504 tuners to match the 402, 403 and 404 Audio Control Centers in the 1959-1961 Custom, Crescendo and Signature models.

The Model 550 integrated Tuner/Audio Control Center in the 1961 Concerto combines essentially the equivalent of a 404 Audio Control Center and a 504 Tuner into a single chassis sharing a common power supply. Provisions were made for an onboard FM Multiplex adapter, but to my knowledge the onboard adapter never saw production.

Note also that the 1957 A423 in Contemporary Walnut was originally referred to as a Crescendo - a designation that was apparently dropped as the other furniture styles became available for the A423 in 1958.

Most pictures courtesy of @byoungman1.
















There is still one anomaly... This gold faceplate tuner that sold on eBay (indicated below as a 504+ ...for lack of other information.) Never seen another of these or the matching preamp.

 

[pete1729]

A while back I read somewhere that there are some high-quality cost-effective Russian-manufactured coupling caps on the market which are highly recommended

I overhauled my McIntosh 240 with parts supplied by Jim McShane. In that kit were Russian K-40-y PIO coupling capacitors for the final stage. The Mac amp sounded great so when I rebuilt my Pilot 1060 integrated I used the same caps. That amp sounded great too. The only other amp I've rebuilt I didn't use K-40-y caps, it doesn't sound as good. I realize this is not in any way a scientific study with controls or baseline measurements.

I am entirely envious of your Ampex rig.

 

[CoastinHome]

The only other amp I've rebuilt I didn't use K-40-y caps, it doesn't sound as good.

@pete1729: Thanks for your comments! I did a lot of reading after that and settled on the use of Russian FT3 Teflon caps for coupling caps in my Ampex 40W amp (0.1uF 600v). I really don't have the luxury of trying out different capacitors... I had to trust the experience of those who do.

The FT3's are in the same class as the Russian K40Y PIOs - which apparently are very highly regarded especially for their midrange -- with the FT3's I'm more than pleased with the sound of this console -- and curious as well how these amplifiers sound with other speakers.

One huge caveat to the use of the FT3's is that they are physically very large. The FT-3's are the three in the inverted T-shape in the photo below. Compare this to to another AK'ers amp further down the page which has K42Y PIO's installed.

 

[gadget73]

I'd go with something of a more reasonable physical size. Things just get messy when you're packing massive capacitors in. Then again I'm the guy that uses basic yellow film caps in everything. They fit and they sound fine.

 

[CoastinHome]

I'd go with something of a more reasonable physical size. Things just get messy when you're packing massive capacitors in. Then again I'm the guy that uses basic yellow film caps in everything. They fit and they sound fine.

I chose the capacitors based on their reputations for performance and reliability -- The challenge of their fitment was secondary. I wholeheartedly agree with you about things getting messy -- or at least very challenging. It made for a lot of extra work using the larger capacitors.

I was surprised how physically large the Sprague Atoms are in the same value vs the Nichicons and others. Also, in wanting to keep a stock exterior appearance to the amplifier, I chose to leave the disconnected original can capacitors in place (even though they weren't matched because one of them was had been replaced in 1968). The polypropylene equivalents of two of the three can sections took up four times the under chassis real estate.

Then there's the polyethylene's I wanted to use for cathode bypass on the output tubes (the third section of the can). Add to that that I wanted to split the value between the two output tubes so that I could evaluate their quiescent currents individually by removing a jumper (after seeing this approach used in a Craftsman 500 amplifier). Those are likewise huge for their values.

And finally multiple polypropylene and polystyrene bypasses on everything except the coupling caps.

I ultimately had to make a 2D model of the capacitors and the chassis underside (in MS Visio) and moved things around until it worked. I'm very happy with the end result but It sure would've been easier to save the "size doesn't matter" thing for an amplifier with a little more room under the chassis. The Heathkit W5-M comes to mind.

 

[CoastinHome]

Okay… Getting back on topic since this thread is about production variants in the 1959 through 1961 Ampex Signature consoles.

Earlier in the week I shared what is known about the model numbers of the variety of preamps used in the Ampex consoles. I was recently able to establish that the silver-faced models with the gray perimeter bezels are considered the Model 404 -- based upon information shown on an invoice for an employee Christmas special.

The 404 may just be a cosmetic change from the 403 (unlike the difference between a 402 and a 403 - which is a redesign of the input switching matrix along with relatively minor circuit changes -- as well as a significant revision of the chassis to move the tubes to the outside).

Yet to be determined is the electrical difference between a 404 and a 403 (if any)...I'll share the details when I get there.

While looking for more collaborating information on model numbers for the Ampex preamps, I encounter the following in the 1962 manual for the 520 FM Multiplexer. (Interestingly, a shipping order from December 1961 for an employee Christmas special shows the multiplexer unit being delivered as a separate accessory -- and bearing model number 511...which I haven't seen referenced elsewhere. The product sheet for the 510 shows a chassis identical to that used on the 520.) Information is amazingly sparse on all of these units. If you own one of the Ampex FM multiplexers, would you kindly comment on the model number shown on the top surface?)

The Owner's Manual for the 520 refers to its use with the 404 Audio Control Center and the 550 Audio Control Center / Tuner combination:



Okay... So now we know that the 404 preamp and 550 preamp+tuner have the auxiliary inputs labeled as "MPX" -- whereas the 403 preamp will have them labeled as "EXT" (because the FM Multiplexer unit wasn't available yet).

And from photos/invoice information that I've collected it is pretty clear that the earlier 404's had the slightly more traditional round style control knobs -- and the later 404's had the paddle style knobs. (Anybody have a better descriptive term here?) All 404's seem to be 1961 models.

Based on the 1962 manual for the 520 multiplex unit, we would expect at least the later "404's" with the paddle style knobs to be labeled "MPX" (allowing for the remote possibility that the earlier 1961 units were still considered 403's in spite of their revised cosmetics) -- And we would expect all of the 550's to be labeled this way.

Not so.

Below is an "Early 404" with auxiliary button labeled "EXT" (So if we trust the 1962 520 multiplex unit manual, this must be a 403.)



Next (below) is an early 1961 with the faceplate labeled "MPX". We can see the multiplex unit in the background. So according to the 1962 multiplexer manual we know this one is a model 404 -- since the 403 didn't use this labeling. Perhaps it was the relabeling of the auxiliary input to "MPX" (and whatever other electrical changes may have been made) which made the 403 into a 404 -- rather than the major cosmetic revision for the 1961 model year? If indeed the round knobs were used on the "earlier" 1961 units -- "early 1961" must extend for a while after April 1961 -- when the Zenith FM standard had been adopted and Ampex was shipping Multiplexer units. Perhaps the knobs were replaced on this unit?



A "later 1961" 404 with the paddle knobs should have been manufactured after the "Early" one above -- and therefore should have the panel labeled "MPX"...right? Hmmm... Guess not. Need more data to confirm that these knobs are used only on the later units -- everything encountered so far suggests this.


If we trust the 1962 520 Multiplexer manual, only the second of the above three is a 504; the others are two different cosmetic variations of the 503. That's not very likely.

So let's take a look at the 550 Tuner/Preamps to see if we can draw some conclusions there. According to the 1962 520 Multiplexer manual, all of the 550's should have their auxiliary inputs labeled "MPX". If we find otherwise then we know we can't rely on the 1962 520 Multiplexer manual to tell us when the preamp model number was revised from 403 to 404.


Here is an "early 550" from 1961 -- apparently the only year they were made. The auxiliary input is labeled "EXT" -- so now we know we can't rely upon the information in the 1962 FM multiplexer manual (which indicates that all 550s have a MPX button).



Here's a 550 with the later style knobs. Maybe the 550's all used the "EXT" labeling?



Nope...it looks like they finally got to it at the end of the model run.
This one was part of the Concerto from an Ampex employee sale -- shipped December 15, 1961. The associated FM multiplex adapter was shipped two weeks later as a "511 Multiplex Adapter Kit".


The console model number is 5752-12...which adds a little more to the mystery of the model numbers for the last units built. Nevertheless, this was probably was one of the last Ampex consoles built -- if not the last.





It remains a mystery for now as to exactly when and why Ampex pulled the plug on making these consoles...

There is a Domestic Price Schedule showing revised pricing and new models dated October 9, 1961. The Concerto above has all the latest features and markings and shipped in December 1961 with its FM multiplexer unit being shipped separately on the last few days of the year.

I've never seen anything about new-for-1962 models. A Domestic Price List showing effective June 18, 1962 shows consumer/commercial accessories which could be used with the consoles (including a "510" FM Multiplexer) -- so reasonably the consoles were being supported through at least mid-year.

A 1962 model would very likely have the second digit of the 4-digit model number either a "3" or possibly an "8". If anyone has an Ampex console meeting this criteria, I would very much like to learn a little more about it.

Perhaps it will become more interesting to keep these things intact -- they certainly represent different times.

 

[pete1729]

Forgive me for the digression, I respect and appreciate what you're doing.

 

[CoastinHome]

Brochure for the earlier 1961 Signature (assuming that these were still being built when the 952 reel-to-reel was replaced with the 1250 near the end of the year.) This brochure shows the Garrard 301 option -- which I have only seen on one Signature console. Same young fellow as in my avatar (from an ad in the back pages of Sunset Magazine). Wonder what he's doing at about 70?

 

[CoastinHome]

Crescendo brochure for the 1961 models.

 

[Jeff T]

I have an early 550 Audio Control with a stereo 6973. The amp and preamp sections are working but both AM and FM tuners are not working. I tested all the tubes except one, can't read the label. The tube label on the chassis has faded. It is a tube located between 2 tank circuits next to the tunning capacitor for the AM. Please post a schematic and any other literatures you might have.

Thanks,
Jeff

 

[CoastinHome]

@Jeff T

Here's Ampex's schematic.

The tuner is on a separate subchassis on the 502/503/504 (indicated Model 008) -- just as it is on the 550. I have to wonder whether the tuner subchassis' were manufactured for Ampex -- perhaps by Fisher as they were on the earlier models.

At first glance the 550 tuner subchassis appeared to be the same as the 008 -- but after looking a bit closer I can see that it is not the same.

SAMS did make available a service package for the 550 Control Center, so you might look for one of those if you need to get deeper into the details.

Hope this helps.

 

[zim bida]

@Jeff T

Here's Ampex's schematllhave to wonder whether the tuner subchassis' were manufactured for Ampex -- perhaps by Fisher as they were on the earlier models.

to me it seems pretty clear that the tuners were made for Ampex - at least in the two signature consoles I've seen - I believe this because they always are completely stocked with tubes from a different manufacturer then the rest of the consoles. In the 1959 signature all the tubes apart from the tuner were Amperex BB, but the tuner was completely stocked with RCA's. In the 1961 signature, the console was stocked with Telefunken's everywhere else, and again the tuner was all RCA's - this includes tubes that were in common to other functions such as 12ax7's. I don't know if it was Fisher, but I can see that being the case as ampex was providing RtR's for Fisher consoles at the time and I can imagine an arrangement being in place for Fisher to do the tuner's for Ampex