Zenith SFD2505

[Motorola minion]

Z forum needed some new material. My last visit to the Delaware Valley Historic Radio Club's Kutztown antique radio expo netted me the entire insides of a 1963 MK2607 and this handsome (record player only) console from 1960.

The strata of Zenith high fidelity consoles in early stereo era, except the smallest tube models.

Top of the line models used a stereo 6BQ5 push-pull amplifier rated for 40 watts. Chassis numbers were 7B30 in 1959 up to 7K31 for 1963. B+ was 380 volts, and 6BQ5/EL84 were Amperex-sourced. Top models can be split into two groups; regular stereo OR extended stereo, which uses split-secondary feedback to alter sound staging, unlike reverberation. The 12" LF speakers 13 oz. cast magnet p/n 49CZ903. Only a few models used a horn tweeters, most were 3.5" cone type.

TV combination models used a stereo 6BQ5 push-pull amplifier rated for 20 watts, B+ was . Chassis numbers were 8H30 and LF speakers used were 12" and 10", both with 6.8 oz. alnico magnet 12" p/n 49CZ852. 10" p/n...

The mid-level models of which the SFD2505 is one, uses a single ended 6BQ5 stereo amplifier that is rated for 10 watts. Chassis 5B29 for the phono-only and 3K32 for models with tuner, B+ was 330 volts. The 12" LF speakers with 6.8 oz. alnico magnet p/n 49CZ852.

The lower cost tube models also used a single ended 6BQ5 stereo amplifier, but rated for 8.6 watts. These can be recognized by the 10" speakers and lower B+ voltage of 295v, chassis numbers 4K21 etc.

Record changers were pretty simple, cobra-matic tonearm and platter trim on a VM built 1200 series. The optional Zenith built belt drive changer was a desirable upgrade.

[Motorola minion]

Zenith SFD2505.jpg (59.32 KiB) Viewed 2052 times

[Motorola minion]

A few years ago, I got one identical to this one in limed oak (blond) cabinet. It was $15 at GW, its original record changer replaced with a seized up BSR. I recapped the amp, added an aux input cord, record compartment lamp and a generic VM changer that just looked right in there. It sold quickly on CL but before I sold it, I showed it off in a big way.

About 6 years ago, our office held its annual christmas party pot-luck in a large room with tables. Past events have featured a boombox with CD's in a small room which is tacky at best for such an event of 30+ people .

The best entertainment was an hour-long acoustic guitar solo by a retiring Architect who moved to AZ. I vowed to bring in a console with records the next time as I thanked him for contributing to a festive atmosphere.

I asked the organizers for permission, who gleefully told me the "big room" would be used. The Zenith was ready and I hauled it in that morning when no one was looking. I stacked about 6 records of poplar folks like Dean Martin, Mario Lanza, Ed Ames, Bing and others. Then flipped the stack, not quite finishing all in the time we had. While this couldn't match the guitarists talent and nobody asked me to buy the Zenith, I could tell it really meant ALOT to some folks. One person told me their grandparents played those same records at holidays and other emotional reactions.

[maxidyne]

Dave, could you get a little deeper into the expanded stereo feature? I have a GE stereo that has a similar feature. How does it work and how would I know if it was not working.

[Motorola minion]

Correction to last post : "TV combination models used a stereo 6V6 push-pull amplifier rated for 20 watts, B+ was . Chassis numbers were 8H30 and LF speakers used were 12" and 10", both with 6.8 oz. alnico magnet 12" p/n 49CZ852."

It seems I recall seeing a Zenith P-P stereo amp using 6V6 outputs not 6BQ5, so maybe it was TV/stereo combination.

[Motorola minion]

Dave, could you get a little deeper into the expanded stereo feature? I have a GE stereo that has a similar feature. How does it work and how would I know if it was not working.

That is possible to describe, but only by using a schematic. Do you know the model number of this GE?

Its my first experience with extended stereo, which only Zenith had??
See ads below, describing the effect. The first ad is hard to read and I have never seen a Zenith like that anyway.

I can confirm this is so, I serviced another Zenith like one in the ad. It sounded pretty neat but too much effect ruins it, like reverberation does to some musical material.

[William]

Thanks, Dave, I have wondered what that was all about. I actually have a Zenith console, similar in looks to the first ad photo you posted. I started the rebuild about a year ago, but soon into it discovered the PT was blown and have had no luck finding a replacement PT. The amp is sitting on a shelf, and the cabinet is in storage. I'm on the fence on what to do with it, part of me wants to pull the speakers and changer and toss the rest, and part of me wants to hang on to it just in case if find a PT. For right now, I'm hanging on to it.

Bill

[electra225]

The GE stereo I have with an "extended stereo" feature is an RP-1590. Zenith's exclusive Automatic Balance Control was a horrible idea IMHO. Every time you changed the volume, one of the speakers would go silent. You have to hold on to the balance control which was behind the volume control when you changed the volume.

The GE stereo only has four 6" speakers. It has removable wing speakers so I think the extended stereo feature has something to do with those, maybe. I have no idea how it works or what its benefit is, particularly on a fairly basic stereo.

I try to avoid Zenith like the plague, but you guys posting pictures of Zenith stereos may let me change my mind. I like the VM changers with the cobra tone arms. I haven't had very good luck working with Zenith in the past.

[Motorola minion]

That balance control was not good I agree, Silvertone also used it on one of thier first stereo models.

There is a friction coupling on that control that is supposed to move the outer shaft, if the coupling screw is tight enough, when just the inner shaft knob is rotated. I have a 1967 X950, which is similar so it lasted a while.

[Motorola minion]

Good news, the SF2505 stereo VM cobramatic has a new home in Phila for a decent price too. The buyer dropped off a 1964 Magnavox Astrosonic 6 knobber for simple enough maintenance (short of caps, etc) I offered gratis for the fair price paid for the Zenith. Best part is, I don't need to drive in this whole deal

The best part is, when I demonstrated the Alexa connection, platter spinning with tonearm resting, all doubts from the buyer about using BT and auxiliary input vanished when I gave my spiel about keeping record changers active. I don't restore changers in mine and let then sit, I use them and when I get the next one to shake out, I sell the console .

I will post a 1959 bill of sale from "Save Master, Bronx" for $ Thanks for following this thread.

[Motorola minion]

Zenith SFD2505 a.jpg (28.09 KiB) Viewed 1584 times

[William]

Thanks, Dave, it's always cool when you find something that has original documentation with it.

Bill