Ampex Signature Console 1959-1961? - Production Variants?

[CoastinHome]

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.

That's a great insight... And it provides the inspiration for me to start tracking which tubes were used where in which consoles.

Interesting that your 1959 and1961 Signature consoles had primarily RCA's in their tuners. I just glanced at my 1961 Signature console -- and the tubes across the back row include a Telefunken -- with the rest being GE's.

In a recent exchange between us, I assumed the original 12AU7 phase splitters in the 1961 40W amplifiers would have been Amperex -- because the output tubes were Amperex (except those replaced with Raytheons). I'm now wondering if they were originally were Telefunkens.

Were there any other EL34 output tubes used besides Amperex in the 30W and 40W EL34 amplifiers?

I think I will start a new thread on the subject.

 

[zim bida]

Were there any other EL34 output tubes used besides Amperex in the 30W and 40W EL34 amplifiers?

I think I will start a new thread on the subject.

the 1959 signature used amperex el34's, unfortunately the 1961 had all the original tubes replaced by the time I saw it

 

[CoastinHome]

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

That does seem reasonable. The tuner used in the 1957-1958 A423 consoles was a customized version of the 80R to meet Ampex requirements. In contrast, the subchassis used in the 502/503/504 tuners don't seem to have an equivalent with the Fisher name on them. I will have to look for any identifying marks on the subchassis (I have a few of these tuners).

In glancing at the back of the 504 tuner in my 1961 I did notice a couple of details which add some insight:

1. The subchassis is rubber mounted -- presumably to reduce microphonics. So that at least increases the likelihood that the chassis and subchassis are from the same manufacturer. (Until I saw the rubber mounting as a reason for having a separate subchassis, I figured that Ampex must've manufactured the chassis and power supply and outsourced the tuner subchassis.)

2. The 504 tuner chassis is stamped with the number "502" - in addition to the four digit serial number and the "Model 008" designation (which appears to be common to all of the 502/503/504 tuners). Very likely, then, the difference between the 502, 503, and 504 models is just the revised cosmetics.

The 502/503/504 tuners all seem to indicate that they were manufactured under licensing by Hazeltine Research. (One of my electrical engineering professors in California back in the early 80s was an old-timer named Richard Hazeltine -- though I couldn't confirm the relationship to the company.)

But for anyone interested in learning a little more about the battle between Hazeltine Research and Zenith Radio, in researching the Hazeltine name I immediately came across the January 22, 1969 court case for Zenith Radio Corporation v. Hazeltine Research, Inc. -- and I was more than surprised to see the audio recording of the three-hour oral argument available: (disclaimer: I haven't had a chance to listen to this yet)

https://www.oyez.org/cases/1968/49

 

[gadget73]

Tube lineup doesn't look right for Fisher tuners. I can't find anything they made with a 6BJ8 tube. Outsourced is entirely possible but I don't think Fisher was it.

Everything was made with licensing under Hazeltine. They had the patent on the AGC circuit that most AM tuners from the early 30s onward used.

 

[Dswankey]

That's a great insight... And it provides the inspiration for me to start tracking which tubes were used where in which consoles. I think I will start a new thread on the subject.

When you do I will be sure to chime in on the 2 consoles I've had in my posession

 

[Djcoolray]

I’ve got a 550, model number 5202

 

[CoastinHome]

Tube lineup doesn't look right for Fisher tuners. I can't find anything they made with a 6BJ8 tube. Outsourced is entirely possible but I don't think Fisher was it.

@gadget73

It sounds like you’ve acquired a bit of experience in working with vacuum tube tuners. Interesting about Hazeltine’s patent on the AM radio AGC circuit. I listened to enough of the 1969 litigation of Zenith vs. Hazeltine to learn that it involved television circuitry.

I’m looking at the schematic now for the 502/503/504 separate tuners. The 550 integrated preamp/tuner “control center” preamplifier (1961) would be the most recent model. It is still is AM left channel / FM right channel to receive stereo broadcasts.

The preamp circuitry of the 550 is identical to that in the 403/404 separate preamplifiers -- yet the tube complement on the 550’s AM/FM subchassis is very different than that of the 502/503/504.

Since you seem to have familiarity with the tube complements different FM tuner manufactures might have used, I’ve attached the full parts list for the 502/503/504 (“Model 008”) tuners to see if anything stands out as especially familiar to you.

Thanks for your input!

edit:
Here's the tube complement for the 502/503/504 (“Model 008”) tuners:

EZ-80 / 6V4
ECC-81 / 12AT7
ECC-82 / 12AU7
EM-84 Tuning Indicator
6AL5
6AU6
6BA6
6AB4
6BK7
6BE6
6BV8

 

[gadget73]

AGC was used in basically everything, but it started out in early AM radios. It was also used for FM tuners and TV sets as well. The original Hazeltine patent was for the Neutrodyne circuit, which was the hot ticket for a few years between the 3 dial TRF radios and the Superheterodyne radios. Not many people were making Neutrodyne rigs by the mid 30s though so that one became fairly useless.


The 6BV8 is an odd one. Can't recall running across anything that used it, but I'm guessing its used as the detector and possibly either first audio or limiter. The rest of those tubes were used by everyone so it doesn't narrow things down very much. A quick poke around radiomuseum turns up Ampex, Hammarlund, and Browning-Drake as the only radio makers that used it. Browning did make FM tuners at one point but I don't know when they stopped. The one I own is from the late 40s. Hammarlund was also more known for amateur radio stuff but either company would have been perfectly capable of designing a high quality AM/FM tuner. No idea if they did OEM work like that though.

 

[Greg Nal]

Reading with interest. I assume I have a '61 Concerto series 5200 console based solely on the literature I found inside. Here's some of the literature I received with it and pictures. It appears all RCA tubes in both the approx 25W/ch stereo amp and preamp/tuner (550 variant). Not intending to be a diversion from the Signature discussion, hoping there is literature or tube set info to add to the discussion.

Greg

 

[Jeff T]

Hi CoastinHome,

Thanks for posting the schematic. I ordered the SAMS schematic as well. The 550 is alive. It was a loose socket at the 6AU6 for FM, and the mystery tube is a 6BA6 for AM band. Most tubes, including the 12AX7 and 12AU7 are by Telefunken, a couple by Sylvania.
It has a very low noise preamp section. I have not replaced any capacitor. Should I replace the coupling capacitors?

Jeff

@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.

 

[gadget73]

its usually not a bad idea, but it depends what they are. Some types are very durable and don't need to be fooled with.


I have a Hoffman console with a similarly constructed tuner on a floating sub-chassis like that.