Zenith HiFi rescued before made into liquor cabinet

[DavGoodlin]

Stopped by Habitat ReStore over lunch break and for $35 I just had to take this HF1284E.
For some strange reason, the legs and captive nuts were inside the box
I have a model HF1284D in Walnut at home which was free but without a record changer

[maxhifi]

Are those electrostatic tweeters? The cobramatic is awesome.. how can you beat that for $35! Are those the legs lined up inside the speaker enclosure?

[Electronic M]

I'm sure those are electrostatic tweeters. Zenith used them in their nicer table radios (I have a few) back then.

[DavGoodlin]

Originally Posted by maxhifi

Are those electrostatic tweeters? The cobramatic is awesome.. how can you beat that for $35! Are those the legs lined up inside the speaker enclosure?

Those are the legs, straight, short and 2" diameter. The other one I have is in worse shape and one leg pulls out fi you move it.

[DavGoodlin]

Originally Posted by Electronic M

I'm sure those are electrostatic tweeters. Zenith used them in their nicer table radios (I have a few) back then.

I do recall the electrostatics in table models, but I wonder if there is a -500 volt supply like Philco HiFi consoles used for electrostatic tweets. My H845 table model has a standard voice coil tweeter. Dial string broken, caps, cig-smoky smell - this one needs some work but I'm motivated to hear what it sounds like.

[Jeffhs]

I have a Zenith K-731 which has an electrostatic tweeter, plus a standard oval speaker (don't recall the dimensions offhand). I also have a Zenith C-845 (similar to the one in my avatar) with a real tweeter speaker and an 8" speaker for lows and midrange. Both radios work well and sound great, considering they are both over 50 years old. They don't make them like that anymore.

BTW, I said the C-845 has a "real" tweeter because I don't consider the electrostatic one in my K731 a true tweeter. I never saw one like that until I saw the innards of my 731. Are these electrostatic tweeters any better or worse than standard ones, and why didn't Zenith design the K731 to use a standard tweeter rather than an electrostatic one driven directly from the plate of the 35C5 audio output tube? I'm sure the K731 was not cheap when it was new, so it probably wouldn't have raised the price that much to use a standard tweeter. The only thing I can figure is that the K731 was a lower-priced version of the C845, which makes sense to me since the latter was introduced several years prior to the 731; my C845 is from 1960, whereas my K731 is from 1963 or '64, and did not have an RF amplifier stage ahead of the antenna.

[rca2000]

I STILL think the 845 radios would have been MUCH better--had they used a 6BQ5 amp with those speakers...instead of ONE 35C5 amp tube. Sure they sound great at LOW volume--but quickly "run out of steam" if gassed any....and "puke out'. With 5-6 true watts from a BQ5...that would NOT happen nearly as easily.

Hence the term 'dentist office radio'...as I hear them described...

[Jeffhs]

Originally Posted by DavGoodlin

I do recall the electrostatics in table models, but I wonder if there is a -500 volt supply like Philco HiFi consoles used for electrostatic tweets. My H845 table model has a standard voice coil tweeter. Dial string broken, caps, cig-smoky smell - this one needs some work but I'm motivated to hear what it sounds like.

The electrostatic tweeters in Zenith radios such as the K-731 are driven directly from the plate of the 35C5 audio output tube, which also poses a shock hazard if you aren't careful. The connectors at the ends of the leads to the tweeter are insulated, but the terminal strip they are connected to isn't, so I am sure one could get a heck of a shock from the latter; after all, those terminals are connected to the plate of the output tube and carry its entire B+ voltage.

[Olorin67]

I have a end table unit wwith that same record changer. It has a unique plug in cartridge that is ceramic. They are getting hard to find. You have to replace the cartridge to change from lp size needle to 78size needle. These cartriges have side contacts, not on the end like the earlier oscillator coil type cobramatic cartridges. Min is suffering from silver mica disease though, really need to fix that first before i dive into the changer.

[dieseljeep]

Originally Posted by rca2000

I STILL think the 845 radios would have been MUCH better--had they used a 6BQ5 amp with those speakers...instead of ONE 35C5 amp tube. Sure they sound great at LOW volume--but quickly "run out of steam" if gassed any....and "puke out'. With 5-6 true watts from a BQ5...that would NOT happen nearly as easily.

Hence the term 'dentist office radio'...as I hear them described...

They should've used a 35L6 or similar output tube with a voltage doubler.
Some radios of the day, even though they were transformerless, used that scheme. The 35L6 and similar tubes can withstand higher B+, plate and screen. Even with push-pull, you can't expect much using only 120 volts B+.

[Findm-Keepm]

Originally Posted by DavGoodlin

I do recall the electrostatics in table models, but I wonder if there is a -500 volt supply like Philco HiFi consoles used for electrostatic tweets. My H845 table model has a standard voice coil tweeter. Dial string broken, caps, cig-smoky smell - this one needs some work but I'm motivated to hear what it sounds like.

Your electrostatics are on page 12, not sure which one of the two is yours:

http://www.talonix.com/REF/ZenithSpkr.pdf

Cheers,

[Electronic M]

I always thought electrostatic tweeters reproduce the high end in a crisper more linear manner than the average cone and magnet type tweeters of the day.

There is always going to be shock hazards if you open the back of a plugged in radio (or any line powered device), the wise understand and deal with it, and the dumb learn the hard way.

[DavGoodlin]

Originally Posted by Olorin67

I have a end table unit wwith that same record changer. It has a unique plug in cartridge that is ceramic. They are getting hard to find. You have to replace the cartridge to change from lp size needle to 78size needle. These cartriges have side contacts, not on the end like the earlier oscillator coil type cobramatic cartridges. Min is suffering from silver mica disease though, really need to fix that first before i dive into the changer.

This is my first cobra-head phono and it has a slide switch that tilts the cartridge to select the 33/45 and 78 stylus. The original cart has no markings on it and is pretty deteriorated. Is this the one?
http://thevoiceofmusic.com/catalog/p...th&Categories=

[Olorin67]

Thats different han the one I have. Mine has no way to switch needles. You either swapped the cartridge, or bought the version that had a 2 mil compromise needle so you could play both types of records poorly.

[Reece]

Comparing the construction of a PM and voice coil tweeter with the Zenith electrostatic, if you ever opened up one of the latter ones you'd see plastic, foil, and foam: very cheap to make.