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Older German console with Fisher Sonic? or I have no idea what im doing

Discussion in 'Tube Audio' started by secondslc, Nov 28, 2008.

  1. secondslc

    secondslc mmmmmarantz

    Messages:
    971
    Location:
    Minneapolis
    Hi guys,
    Please be nice as I am a solid state Marantz guy that is starting to look at tubes. I know its a slippery slope, but I think tube guys are willing to grease it up for me :D.

    About 5 years ago, the console stereo we got from my grandmother stopped turning on. Knowing it was a tube radio, i thought a tube burnt out and I replaced ALL of them with exact replacements. Needless to say, I am a more educated person, and realized that this radio also has fuses.

    Coming back to my parents house, I found the culprit fuse and replaced it. After letting it warm up, sound started playing :D. I think it sounds darn fine for what it is, I was just wondering a few things.

    I'm not selling this unit, its got too much sentimental value, plus I think it looks cool :). but some general info is great.


    (1) The console says "Koronette" and was made in Germany (East). The radio part itself says Fisher Sonic. I am wondering if it was a common unit to put into consoles, and how they rate for my first foray into tube gear. The sound to me is very crisp in the lows, but with a nice full midrange, the top end is limited by the speakers, but still sounds good. A very good ambiance type system as we used to use the radio for holiday dinners.

    (2) Upon initial turn on, there was lots of buzzing and hum, Could this be the replacement tubes turning on for the first time?

    (3) There are two plugs for additional speakers. The writing says NUR FUR WECHSELSTROM LEISTRUNSAUFNAHME 80 WATT. Can I run another set of speakers? I would like to run some KLH 17s or 23s...But I dont know how much stress a tube console can take?

    (4)There is an underlying 60Hz hum on the system even with the volume at 0. What should I be looking for to address this?

    (5) There is a pair of tubes that seem to indicate tuning strength and MX or STEREO. The tuning meter seems to work, but nothing comes out of MX or STEREO. Hitting the stereo switch cuts the sound completely, am I missing anything?

    (6) The balance doesnt quite work, would this unit benefit from a de-oxit bath?

    (7) There is no AM reception, what should I look for?

    (8) I am assuming the tuner section is solid state, the tube count is too low for a tube tuner.?

    I am sure I will have more questions as time goes on...but for now ill just include lots of pictures.
    [​IMG]

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    [​IMG]
     
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  2. gogofast

    gogofast AK Subscriber Subscriber

    Messages:
    7,981
    Location:
    Seattle
    wow, what a fine piece of stereo art!

    i'm specially digging the "refreshment compartment" in the middle. wait, is that a bible by the turntable? nice.....read bible while sipping on some liquor.

    before you even begin to look into individual problems, you will definitely need to replace all the capacitors including the power filter caps that might be causing the hum at zero gain.

    i hope you saved the tubes you pulled out. most likely, most of them are fine. plus, you can't just swap output tubes (el 84 in your case) without checking the bias (see how the new tubes handle the voltage) specially if you used new production tubes. (unless you had spare tubes that came with the console)

    you will also need to realign the radio sections for stronger reception.
     
  3. relaximus

    relaximus Consoles 'Я' Us Subscriber

    Messages:
    5,579
    Location:
    Where the hell is Canton CT?
    Hello and welcome to the "Warm and Glowing" side!!!

    That is one beautiful console! Do you have any idea as to its year? It sure has a mid 60's look to it, but I may be way off. Is the cabinet a veneer? That high-gloss, lacquered finish is absolutely stunning.

    I'll try my best to answer each of your questions in order. Hopefully, others far more knowledgeable will chime in as well:
    1. Being from East Germany, my (uneducated) guess would be that the electronics are re-branded from an outside supplier. The cabinetry itself (which a work of art IMHO), was likely the only thing actually produced by the manufacturer.
    2. Not likely to be the tubes. There are extremely high voltages coursing through these old tube stereos, so the initial surge of (especially today's) line voltage can produce all manner of weirdness in these units. I hope you kept the tubes you pulled out. Vacuum tubes have a surprisingly long lifetime. And it's quite likely that any new production tubes, you may have used, will sound worse than what you pulled out until the amplifier is re-biased and the new tubes are broken in.
    3. My only advice here is to be careful of whatever impedance load you place on this unit. These old girls are not particularly fond of anything falling much below 6-8 ohms. Frying an output transformer can spell death for these things as those parts are often classed as "unobtainuim". Especially so in the case of your console.
    4. A 60 cycle hum is pretty indicative of the need to replace the filter, and most likely, coupling capacitors. The old electrolytic filter caps, especially, have a limited lifespan and tend to get a little funky after 30-40 years. You can try reversing the polarity of the plug in the power outlet and see if the hum diminishes somewhat.
    5. It was not uncommon that an add-on multiplexer was optional during this time. Just because the selector offers "FM Stereo", does not necessarily imply the unit's ability to actually receive it. Then again, this may be due to dirty contacts in the selector.
    6. Definitely! All of the switches and pots would greatly benefit from a thorough cleaning.
    7. No static or anything? This may also be due to a dirty function selector switch. Cleaning is cheap and easy. Start there and then move on to whatever other problems are left.
    8. There certainly looks to be some solid state circuitry from your pictures. This definitely appears to be a hybrid of some sort. This would make sense if my guess holds true as to its age.
    Definitely take more pictures as you get further into it. I, for one, would be very interested to know just what the driver complement is. As the tube layout would seem to show, a single pair of EL84's may indicate a single-ended amplifier. However, they may well be wired in a push-pull triode configuration. Either way, I'd guess the output to be around ~7-8 watts per side. You also have what, I think, are dual-triode tubes in there. These were used in the front-end of some FM tuners of the era as the transition to solid-state progressed. This would also appear to be tube-rectified by virtue of the EZ81 on the tube layout. But then, I'm still learning as well, so others will likely correct me if I'm wrong. Let's hope so! ;)

    Discarding everything else, that is one beautiful and unique console. It is fully deserving of whatever care and restoration you can provide to it. Count yourself among the lucky with that unit!

    Best regards,
    Dave
     
  4. NYListens

    NYListens CBGB & OMFUG

    Messages:
    2,638
    Location:
    New York
    Ultra cool. Just imagine that thing in a basement bar area with a nice early 1940s type Hawaii theme to it.
     
  5. Fisherdude

    Fisherdude Regular Dude - Super Mod Staff Member Super Mod

    Messages:
    26,897
    Location:
    Out West.
    What a beauty!!
     
  6. truep

    truep Active Member

    Messages:
    166
    Location:
    Flower Mound, TX
    Most likely it's all tube, but doesn't have a multiplex unit for FM. The tube complement is similar to a grundig AM-FM-SW I have.
     

     

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  7. Tom Bavis

    Tom Bavis Audiophool Subscriber

    Messages:
    9,027
    Location:
    Macedon NY
    REMA 2070D is a 1967 model, "chassis for custom installation", according to radiomuseum.org. No schematic or other information, though.

    3 w/channel from SE EL84s won't drive a pair of KLHs well...
     
  8. relaximus

    relaximus Consoles 'Я' Us Subscriber

    Messages:
    5,579
    Location:
    Where the hell is Canton CT?
    Ouch! 3w/side, I guess I was way off!!! Got Klipsch? ;)

    Dave
     
  9. markus

    markus Master Procrastinator

    Messages:
    4,104
    Location:
    Miami Springs FL
    just for the record, I have run a pair of KLH 6's off a little 3 wpc EL84 sylvania console amp, and it sound REAL nice. . . wasn't shaking the walls, but with its limits, the setup sounded real nice . .

    I'm betting the Hum is caused by leaky PS caps. . . A heavy does of Deoxit may be enough to take care of the stereo switch issue . .. not sure of the AM reception issue - maybe post over in antique radio ?

    that might be the most beautiful console I've ever seen :yes:
     
  10. secondslc

    secondslc mmmmmarantz

    Messages:
    971
    Location:
    Minneapolis
    Wow, thanks for the replies guys!

    I asked my father about the radio, it was bought for ~350 in 1964. The cabinet is solid wood with a lacquer finish. My grandmother wanted it because it was the prettiest. My grandfather said no when they were at the store....and just brought it home one day as a surprise.

    (1) flipping the plug does nothing, she probably needs a re-cap, i just dont want to damage anything when I pull the radio out, any advice on how to take it out?

    (2) The cartridge is really noisy and scratchy, it says "BSR made in england", i know its a common brand an ill take more pictures of the turntable, its a little slow, but i think the auto stacking system works.

    (3)The tuner dial (glass btw) does say fisher sonic, does that have anything to do with the fisher we all know?

    (4) I have all the old tubes, should I just re-replace them? Or does each tube get matched with each socket? Do tubes short to where they blow the fuse, or should I worry?

    (5) The speaker "out" says 4 ohm, i know it may be pushing it...but wouldnt the amp be designed to handle that?

    (6) So KLHs are out, what can I use thats efficient on the 8 watt output?

    (7)I love tube power where 3 watts is considered plenty :)

    Really, thanks for the compliments guys! I remember my grandmother hiding money in the "refreshment compartment" and just loving how shiney the wood was. I want to give this console a restoration it deserves, anybody in chicago want to show me how?
    [​IMG]

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  11. Captain Scary

    Captain Scary On Island Time

    Messages:
    1,226
    Location:
    Bailey Island,Maine
    Gorgeous console!!!

    What a handsome n special heirloom
    that is.
    I have one very similar component wise but
    it has the cheesy fake fireplace
    down below.
    Have only listened to mine briefly but
    had a very pleasant sound too it.

    Hope you get it freshened up and enjoy........

    Cheers,
    Barry
     

     

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  12. gadget73

    gadget73 junk junkie Subscriber

    Messages:
    36,986
    Location:
    Southern NJ
    Looks like telefunken tubes. Good stuff, I'd probably plug them back in. More likely the fuse blew due to a capacitor failure. The hum also seems to point towards a failing/failed filter cap. When they go bad, they draw more current.

    I'd guess this is a hybrid set, tube outputs and front end, but probably transistor IF stages, and probably solid state AM as well. Tube lineup seems to indicate thats likely. Early solid state FM sections were not particularly good. Ironic, a solid state failure is quite possibly the trouble with the AM stage. Of course its also just as likely to be funky contacts on the piano keys. I've got a couple Euro radios from that time, and when the switches get dirty, they go stupid. My Norelco has a partially dead SW band unless I hold the switch shoved down.

    tube lineup:
    EZ81 - rectifier. THis is the only one I'd possibly be concerned with. If a filter failed, it could have taken the rectfier out.
    ECC85, probably FM RF amp. Its a dual triode.
    ECH81, pentode/triode probably FM mixer
    EAF801, pentode / dual diode. FM detector possibly?
    ECC83, twin triode drivers for the output tubes
    EL84 pentode output tubes
    EM84 - the eye tube.

    Usually the chassis is held in with a couple of screws. Hard to say without looking but I'll bet if you look around underneath you'll figure it out.

    This is a bit of an odd set, coming from East Germany. Not a lot of stuff made it over here from beyond the iron curtain. I also seriously doubt it has any relation to Fisher, the US company.
     
  13. cademan

    cademan Addicted Member

    Messages:
    9,045
    Awsome unit! :thmbsp: Just a suggestion, try holding the FM button and pushing the stereo button at the same time. I know a friend of mine had a weird german radio that used to operate this way. Or.......maybe it really does need the optional MPX unit.
     
  14. resound

    resound Super Member

    Messages:
    1,843
    Complete sweetness,
    Thats a keeper.
     
  15. relaximus

    relaximus Consoles 'Я' Us Subscriber

    Messages:
    5,579
    Location:
    Where the hell is Canton CT?
    Wow, that thing is so unbelievably clean inside! And from '64? That is truly a beautiful piece. Those speakers sure say Telefunken, at least to me!

    Dave
     
  16. secondslc

    secondslc mmmmmarantz

    Messages:
    971
    Location:
    Minneapolis
    Nudies, some more goodies and some more questions!

    I got the amp/tuner out of the cabinet without much drama. Two screws and the unit slid out on a wooden base.
    The unit was purchased in 1968...i was off on the year. Reason I found out is cause I found all the documentation as well as a non stacking adaptor for the turntable in the original envelope. Documentation includes the Radio manual, console manual, schematic, and warranty type card.

    (1)The ferrite antenna is sitting on top, nothing is attache to it, shouldnt there be?
    [​IMG]


    (2)The schematic is on large scale paper, I can go to kinkos and scan it in if it helps you guys help me get everything going.
    [​IMG]

    (3) The markings on the power filter caps are confusing. They only have two terminals but are marked 50uF +50uF. Do I go with the larger of the voltages? And what does the 9.68 number mean as the other cap says 8.68. Should I worry about the smaller caps that live where the tubes are?
    [​IMG]
    [​IMG]


    (4)The turntable needs a cartridge or something as it sounds scratchy, any advice? The cartridge has two needles, one for 78, the other for LP. It is a BSR cartridge made in england?
    [​IMG]

    And some more pics for fun, if anybody can shed more light as to how this radio is built or its specs, that would be great. Pardon the dust, we never did go behind the unit.

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    [​IMG]
    The manual mentions a stereo decoder, but I dont think it exists for FM, supossedly, one is built into the turntable.
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    The finish is like that on the whole cabinet.
    [​IMG]
     

     

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  17. gadget73

    gadget73 junk junkie Subscriber

    Messages:
    36,986
    Location:
    Southern NJ
    50+50 uf means its got 2 caps in it. Most likely the case is the common negative.

    The 868 and 968 markings I'd deem meaningless, maybe a manufacturer's part number. The uf and voltage ratings are what you need. I'd replace the cans, the silver electrolytics on the circuit boards, and if there are any paper caps underneath do those too. You should find a couple around the output tubes. If I had to guess, they're the tan/brown things just above the tube sockets.

    The ferrite bar ought to have 2 wires going to it. Maybe the black and yellow leads I see twisted together? I can't tell if they hook to something or if they're simply laying there. If they're hooked to something, look around for wires that seem to just be hanging out.
     
  18. Thespeakerdude8

    Thespeakerdude8 Super Member

    Messages:
    2,037
    That thing looks mint! What a gorgeous console! Germans made some pretty darned good stuff. The OT's on that look nice sized too. :)
     
  19. secondslc

    secondslc mmmmmarantz

    Messages:
    971
    Location:
    Minneapolis
    OT=output tube?
    sorry...stupid solid state guy (SSSG) here ;)
     
  20. Thespeakerdude8

    Thespeakerdude8 Super Member

    Messages:
    2,037
    Output Transformers, sometimes OPT is used. The part that couples your High impedance tube to your low impedance speaker.

    They look larger than average for your typical SE EL84, so their LF responce should be pretty nice. :thmbsp:
     
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