Quote:
Originally Posted by anden
These 7 & 8 tube Zeniths are indeed great.....starting in about 1955 they included electrostatic tweeters on either side of a 8 inch main speaker providing fantastic audio. Zenith changed to a 5 x 7 inch oval speaker with one electrostatic in about 1958......still sounded great.
Many folks think they date to the early fifties due to the last patent date being 1951, but they're later...the y832 & B835's are 1955-56 and the G730 is 1958. Then the popular K731 is about 1963.
Zenith really ended the era of tube radios with a bang ! I bought three today at a radio show - a H845 for $10, a K725 for $20 and a neat tube portable for $ 8. All work ! It was a good day.
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You are so right as to the popularity of the K731 in particular, as I see those sets on ebay all the time. Zenith must have made millions of those sets in their heyday. (By contrast, the MJ1035 doesn't show up on the bay nearly as often; I've seen only one such set there in the last couple weeks or so.) I have a K731 that still works, looks and sounds great after 45 years (all it needs now is a new power cord), a C845, and an MJ1035 that both still work as well as can be expected of radios of that vintage (the MJ1035 has a bit of power-supply hum, but I knew about that before I got the radio about two or three months ago). The MJ1035 and C845 in particular are excellent when it comes to RF sensitivity; I live between two cities and can hear both areas' major FMs on these radios just fine, in addition to two stations some 60 miles south of here, using only a 6-foot length of wire on the FM antenna terminal.
The K725 is basically a K731 in a plastic cabinet. I have a schematic for the K725 that is apparently close enough to the '731 that Zenith (and apparently Howard W. Sams) didn't bother to publish separate service info for both receivers.
I'll have to look inside my C845 and MJ1035 again to see if I can find the second tweeter; the last time I had the back off either set I only saw one high-frequency transducer.
Zenith did not use the plastic-cased electrostatic tweeter in the C845 or the MJ1035; in its place in at least these receivers are two standard 5" speakers on either side of the 8-inch main driver, which is fitting for these sets since they weren't cheap when they were new (the C845 probably sold for over $100 when new in the late fifties, while the MJ1035 sold for close to $200 when it was new in the early 1960s). The K731 may have been meant as a lower-end table radio, with an audio system to match (one 35C5 output tube, with a section of, I believe, a 19T8 being used as the preamp--the electrostat tweeter is driven directly from the plate of the 35C5); this is not to say the 731 sounds bad--on the contrary, it sounds very good for a small table receiver, considering it has the 3" plastic electrostatic tweeter. One thing these Zenith radios had that many other table sets of the same vintage did not have was a true tone control, i.e. a control that adjusted the entire frequency response curve of the audio stage rather than simply cutting the highs.