Classic Hifi Care

About 5 years ago, while in Arizona, I found a Big Imperial listed on Craig's list back in Michigan. Go figure, right! I called the seller to find out more info and learned it was his grandmother’s, and he wanted it to go to a good home. I explained that I was in AZ and needed some time to find someone to pick it up for me. Not a problem said he, it just needed to be gone by spring as the house was going up for sale then. I made a few calls to friends back I Michigan and arranged for payment and pickup. The friends would keep it at their house until I returned in the spring.
Fast forward three years the Imperial was next on the list for a rebuild. Fortunately, the cabinet was in excellent condition, so, all needed to do was the electronics. Well, that turned out to be quite the experience. I did the normal cap replacement, tested resistors, and, replaced those that had drifted. Next, I did the final voltage tests to make sure all voltages were good. Having that out of the way, it was time to fire it up. Expecting to hear beautiful music, I was disappointed to only hear music from the LH channel. Wait a minute, if the volume was between 0 and 1 or max the RH channel played. OK, what did I do wrong? Back to the drawing board to recheck everything to see what I screwed up. After double and triple checking my work, all seemed good. Now what? At this point I consulted with people much smarter than me, and, with their suggestions started to work my way thru this problem.

Jumping ahead a little bit, I paid a visit to my local electronics store for a couple of things. I was telling Mike about the problem, and he asked if I had a signal tracer. I said no, he said just a minute. The next I knew I had a signal tracer. It was the one from his second bench that he did not use anymore. Since I had never used one before I said how do you use it? He explained the principal behind it and how to use it. I said thank you, and off I went.

Again, I fired up the Imperial and started testing with the signal tracer. I used the input from the changer as my source with all the components of the Imperial scattered all around the cabinet so I could have the speakers hooked up. (I hate the way Magnavox has their speakers wired together) Starting at the phono input I followed the signal all the way to and through the function switch. I had good signal to that point. From the function switch to the couplet on top of the volume control was good, but the signal coming out the other side of the couplet lacked one channel. Hmm! I had already tested the ohm reading on the dual volume pots and they seemed ok. I scratched my head for a few days and then got brave and pulled the volume pot out of the chassis and decided to pull it apart. Much to my surprise, one of the pots did not have any resistance strip in it. It was gone! So, how did I get a reading when I tested the pots? The reason I had volume at both ends, the sweeper was bottoming out at both ends of the pot. Finally, the problem is solved.

Not quite! It seems double volume pots with the values I needed do not grow on trees. I first went to Mike to see if he could order one. Nope! Next, I searched the internet for new or used. Nope, close on a couple of occasions but not good enough. Finally, a friend suggested a supplier that has lots of vintage odd stuff. I contacted and waited. I contacted again and waited, no response. It was either the third or fourth time I finally heard back. Yep, I think I might have one. I’ll get back with you. Again, I waited with no response. Finally, after about a month I heard back and, yes, he had one. He told me how to order and pay for it and once I had completed that task, he would ship it. It was close to another month before it arrived. I installed, it worked, and all was good.

Not quite! I played the radio and it sounded great. I played a record and that sounded even better. When I went to switch back to radio the Imperial went dead. What! There was no power anywhere. Everything came back out again to see what was going on. Would you believe, the switch that is attached to the back of the function switch failed. That switch when in the phono mode allows the changer to shut everything down once the records are done playing. Again, something that is specific to Magnavox and not available in the normal world. But guess who had one? Yes, the same guy that had the volume pot. He warned me that it would probably mount differently, and he was correct. As I’m trying to figure out how to make it work, I decided I wanted my Imperial to work so I could enjoy it. What I did was a little bypass surgery. I bent a bracket out of aluminum, drilled a hole in it and mounted a switch. I extended the wires from the tuner to the switch and then mounted the switch to the back of the cabinet. Hallelujah, the Imperial lives! I have radio when I want it, and I have records when I want them. And the changer shuts off everything when done.

One more thing. If I’m understanding what Greg has told me about the way his Imperial sounds, this one is nothing like his. Mine, sounds awesome! It reproduces the music on records as records should sound. It is full and rich and powerful. Magnavox must have done something right on the last year they built the Big Imperial, which by the way is not supposed to exist.

Bill

Nice job of hunting down the problem! Now you have the reward for all that effort... enjoy the music!

William, That's great how you outlined the adventure of getting and then finally enjoying your find. I have the same enjoyment with each one of the few I have found. Hydro

Congrats, Bill, on a beautiful job on the build!. I know how much work you put into this. You hung in there during some pretty disappointing/frustrating moments. I believe, if it had been me, I'd have hunted around for another tuner chassis and had it done. You actually went to the trouble to fix the one you had. I have a lot of respect for that. Nice job on the pictures as well.

I'd like to do some experimenting with my Imperial. Since yours sounds so good, perhaps I could put the two schematics side-by-side and do a comparison on component values. Then, of course, I'd seal up the speaker enclosures. Something HAS to be wrong with mine.

Hello Again, Greg I feel the same way about the continental It has a bigger amp 182 the tuning eye 54 series preamp the great cabinet which is losing its nicotine smell over time and the more that I clean it. The sound just has been a battle the horns work great but the woofer is just not there its like you have the bass knob turned down and when the volume was up it distorted easily. Part of it is the cabinet there were a lot of loose screws shrunken wood that allowed for movement but I also think it is the speakers hardened up paper cones, years of sitting and just not being used. I ran it about eight hrs before you guys diagnosed the B+ issue with the tuning eye. It had a very slow three minute start up where the first minute the woofers were trying to work and gradually gained volume. The next couple of minutes the stereo just seemed to improve. But stabilized at what I seem to think is 50% of its capability. Once I figure out how to measure impeadance accurately I want to substitute another set of speakers or possibly new speakers. There may be something to the enclosed speaker cabinet however as the 60 CG just takes off from where the continental was struggling. When I get the tuner and amp back from Golden radio repair, The setting of the AMP 182 biamp pots will be done like the Sams says. (Photo) Hydro

Hello Bill I think I have a switch for you on a parts chassis from ebay, its a 57 series 57-12-10 and I also have a spare 57-01 for the continental but both are for parts. I tried to load them in the PM but idk how to insert images there. I think your referring to the extra stacked switch on the main selector switch. Hydro

Great restoration story! We all hope for great sound at the first power-up, and it's disappointing if we don't get it.

Chris Campbell

Mornin' Hydro ! I mentioned to Bill when he was working with his tuner chassis that I thought somebody, maybe you, had a parts chassis. I wasn't sure about it. I'm glad you posted pictures of your parts chassis, that might be what he needs.

To be frightfully honest, while not intending to sound negative, my Concert Grand is not the king of bass either. I don't think it's much better than the Imperial. And, again to be frightfully honest, I have owned and used a Pioneer SX-1050 for so long that I may have become "spoiled" with an unrealistic expectation of exactly what adequate bass response is. Those big integrated amps of the '70's accentuate bass to incredible levels. Our old low-wattage console stereos were never intended for that kind of performance. Old, stiff speakers are something I have considered as well. Parts Express has replacement 15" woofers that are cheap enough to buy and see if they help. I'm a little hesitant to try wholesale speaker replacement, as Magnavox tuned the electronics to the speakers to the cabinet and the replacement of any one of the three might upset the entire system so nothing sounds good. I believe the course I'll follow is to re-check the condition of every component in the entire instrument to see if any have drifted. Then see if there are later revisions of the chassis and compare the later versions to the one I have. I don't expect, or even desire, performance from a console stereo to be like that of a good component system with 120 watts per channel. I honestly believe it can be better than it currently is.

Maybe I'm just naive and don't know what real bass should sound like, but my Concert Grand puts out what I believe to be supurb amounts of bass.

Point well-taken. I may be looking for something that was never supposed to be there in the first place.

I would post a video, but that wouldn't help. I'm sure you would have to hear it in person.

Thanks for posting the photos, Hydro. I will take a closer look and send you a PM. I'm not sure which model would be the closest to what I have.

Bill

Nice Job Bill! .... isn't it a great feeling to know you restored a classic and you get to reap the rewards of great music reproduction!

Could you access the service literature for your tuner and for Hydro's parts tuner and compare part numbers on the part you need? That might help determine if they use the same part. Good luck.

Good to see you back on the forum, Elton !............

Thanks, Elton. How's the project coming along?

Bill

Theoretically, good low frequency bass, as opposed to exaggerated booming bass at, say, 100Hz, is a matter of the right drivers matched to an acoustically-designed enclosure. Did any of the Maggies of that era employ ported, bass-reflex, or acoustic suspension speaker enclosures? I recently saw in a 1972 catalog that Mag used styrofoam enclosures mounted inside their speaker compartments, sort of like Stromberg did in the early '60s with a bass-reflex box enclosure of non-resonant Homasote-like material that was mounted in the speaker compartment. I've also read that CGs?, I think it was, did have sealed speaker compartments? Not many consoles did this, but correctly designed enclosures should provide the greatest improvement in good bass response.

To answer your question, Magnavox did start that type of speaker system with the Astro-sonic consoles. But, I think it was more in the later 60's than the earlier Astro-sonics. I believe the "sealed" speaker system came along when the cabinets started to go cheap.

Just to add this note, my Imperial has sealed speakers, that is to say they plugged the hole in the bottom of the cabinet. The rest of the speaker enclosure was already boxed up. Greg's is the same, except he does not have the plug. I believe his is a 1960, maybe 1959, I can't remember for sure. Mine is the Imperial that is not supposed to ever have been built. It was the end of the tube era, and, I believe Magnavox was using up all the tube components because the Astro-sonic was already out. They had left over components to build a few more Imperials, so they did.

Bill

Hydro, I sent you a PM with some info about our respective tuners.

Thanks, Bill

Yep the cabinet that my R231 receiver would come in does look like they were cheap-ing out, plastics, gaudy designs, more particle board...it's a shame that evidently their SS receiver's amp + tuner sections were pretty well perfected by then and they were putting speakers in enclosures, at least they still maintained standards on the most important music-making stuff.

Why don't you find a 1963-64 SS model with the hardwood cabinet and put your guts in it? They are fairly plentiful still and they are the old tube cabinets they used until they ran out, then went to the plastic and particleboard cabinets.