Mating a Fisher 440 Amp to a 490-T Tuner

Discussion in 'Fisher' started by audmod01, Jun 6, 2017.

  1. audmod01

    audmod01 AK Subscriber Subscriber

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    Larry;

    Thanks for this information. Now I know what to do going forward. I like the fact that the unit is equipped to handle a magnetic cartridge input. I thought it appeared to have that incorporated by the 12AX7 stages for phono looked just like those on the model 400 and 500-C etc.

    Joe
     
  2. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

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    If you don't want to disconnect the Loudness circuit completely, you can disconnect at one end or other and install a DPST switch to toggle the loudness on or off. I should have done that, but that would have entailed a long run of wire thru the tuner to the back of the console. So I just dis-connected at the Volume pot.
     
  3. audmod01

    audmod01 AK Subscriber Subscriber

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    Larry and others who are familiar with Fisher bookshelf speakers:
    Given that the 440-A amp is going to have a low power output compared to Fisher equipment with 7591 or 7868 tubes, what Fisher bookshelf speakers would work well with the 6BQ5 push-pull output stages? Suggestions?

    Joe
     
  4. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

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    Really any of them. I've got a pair of 55-B's that handle EL-84's all week and twice on sunday. They'll handle my SANSUI 1000A or 800c without too much trouble either.
     
  5. audmod01

    audmod01 AK Subscriber Subscriber

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    I had been listening to the Electra 440-A & 490-T combination over the last several days and found its low end response really anemic (as in almost nonexistent below about 200Hz). As mentioned before, the volume control had loudness taps on it and as it turned out, Fisher had used it with just some 22K ohm resistors to signal ground. What this did was just equalize the volume level in the lower half of control rotation. I went ahead and installed .022 caps to the 22K resistors from the tap (in series) and added two 75pFd caps from the high ends of the volume control to the loudness tap. This completes a loudness compensation circuit which will be in circuit all the time. If less bass is desired it can be reduced with the bass control. I also increased the output coupling capacitor value from the 12AX7 plates to the tone control circuit and added a 25uF@10VDC electrolytic across the 1K ohm cathode resistors. The capacitors from the phase inverter stages in the 440-A were also increased in value. All these changes resulted in a more normal range of adjustment for the Electra combination. I have been using it with some acoustic suspension speakers that can handle up to 60 watts. They are not terribly efficient, but do not take enormous amounts of wattage to drive to listening levels. Still they are somewhat more difficult to drive than what Fisher may have used in the original Electra cabinet.

    One channel is real slow to come up to normal volume. The 12AX7 that drives the tone control circuitry etc. is an OEM unit from the early 1960s. It has seen its better days. I have a number of new tubes coming that will likely solve some minor issues I have noticed with the units.

    Joe
     
  6. gadget73

    gadget73 junk junkie Subscriber

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    Series string tube heaters that work off the output tubes can be a little cranky like that. Differences in construction and general health make it come up slow and uneven. The phono tubes in my TA-600 work that way. The right comes up before the left, and both are slow. Not much to be done about the speed though.
     
  7. audmod01

    audmod01 AK Subscriber Subscriber

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    Gadget;

    Yes I also have an H-K A300 that I bought new back in the early 1960s. I still use it occasionally. The older the tubes get the slower they are to come up. The output tubes have to be included in that response time because they provide the DC the 12AX7 filaments are operating from. If the output tubes get weak the preamp and line driver tubes get slow to warm up too. The tubes I currently have in the Electra came from the A300 and the 12AX7 I installed in the line amp circuit is one of the original tubes from that amp. One half of the filament appears to be warming up faster than the other one. This is V10 on the 490-T schematic. V10 amplifies both channels and one channel warms up much faster than the other one. The balance control has to be turned far to one side to hear the other channel until that side warms up enough. Once its warm-up has been completed (about 5 minutes on average) then the balance control can be returned to center position. This is while the unit was being operated on FM mono or AM. The same was true if I fed a mono signal from the 202-R tuner either AM or FM.

    The 440-A amp/pwr supply chassis has all new tubes in it, so its part of the operation is pretty standard in warm up time.

    My wife just handed me the AES tube order for the Electra and 202-R delivered by the postal service. Time to stop and give them a try!

    Joe
     
  8. audmod01

    audmod01 AK Subscriber Subscriber

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    A new 12AX7 in the V10 position did cure the uneven audio at warm up. The warm up is still slow, but now the audio is balanced when it does become audible. A new 6AU6 limiter in the FM IF helped the reception slightly. A new 6BA6 in the FM 1st IF helped the overall IF gain and improved the multiplex considerably on the one difficult station. One particular new 12AX7 seems to have improved the stereo action and lock on the one very difficult to receive FM stereo station here. It was installed in the 19kHz amp/threshold stage. The other 12AX7 tubes tried in the rest of the multiplex made no difference.
     
  9. audmod01

    audmod01 AK Subscriber Subscriber

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    Larry;

    I just ordered a set of Fisher XP-55B bookshelf speakers for this system. The ones I picked look to be in very good shape. I decided these were the best choice for a girl to deal with in a college situation. While 10" woofers would be nice, the units so equipped are pretty heavy. I can vouch for that because of my own AR-2Ax speakers. These are a little smaller and lighter, but still have acoustic suspension 8" woofers and a tweeter. The sound should be pretty decent. Once I get the speakers in hand, I can go about constructing an equipment cabinet for the changer and tuner/preamp plus output stage/power supply.

    I haven't decided yet on a changer. I would like to find one with a cue lever to slowly lower the tone arm during manual play. This will help avoid record damage by someone not used to dealing with LP and other type records. My granddaughter falls into that category. She will learn quickly, but I would rather avoid trouble from the beginning if possible. Some actual instruction on my part will be necessary anyway.

    Thanks again for your input!

    Joe
     
  10. gadget73

    gadget73 junk junkie Subscriber

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    Later Garrards have that. SL-95B or Zero-100 do at least. I like my Zero-100 fine, but the arm is a bit weird. The 95 has the same mechanism but a more typical but sexy wood arm instead of the convoluted pivoting thing the Zero uses.
     
  11. audmod01

    audmod01 AK Subscriber Subscriber

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    Gadget;

    How much do the typical SL-95 or Zero-100 weigh? I don't want to get the whole assembly too heavy. Perhaps I should consider the changer in a separate base with cover. That way the weight per piece could be kept down. Most of the older Garrard units are pretty heavy. I have an RC88-4 in the cabinet with my E H Scott 800B and I installed a Garrard Type A in the Silvertone 8127D I gave to my daughter. Both of those are pretty heavy. I had an AT-6 for many years, but its tone arm interface to the cartridge head-shell went bad so it is sidelined for parts. Those AT-6 models are lighter than the RC88 and Type A by a considerable margin. One of these days I need to relubricate the Type A 70 that is part of my Dynaco system. It has gotten sluggish lately.

    Joe
     
  12. gadget73

    gadget73 junk junkie Subscriber

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    My zero-100 in the wood plinth is maybe 20 lbs. I can weigh it if you need specifics but its not stupidly heavy. Its probably a little heavier than the AT6 just because of the larger size, but its not like the Type A. I have one of those and an RC-88. I don't know if the 95 is much different in weight,but I doubt that it is. Same basic mechanical package, different arm.

    One bad thing about the late ones is actually the headshell setup. It uses this plastic slider that connects against some spring fingers. I've had trouble with mine, though once you get it clean its not bad. The 100 has a tilting setup on that for auto/manual operation. I don't think the SL95 has that, so it may be less touchy on the contacts.
     
  13. audmod01

    audmod01 AK Subscriber Subscriber

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    If I can find either the SL-95 or a Zero-100 with base and dust cover, that may be the best way to go.

    On the headshell arrangement, contacts can be an issue with most any magnetic cartridge due to the low voltage and current involved. One thing I have done is to put a thin coat of silicone grease on the contacts after doing a good cleaning and this helps keep them clean oxygen free to cut down on future corrosion. It would have been nice if silver or gold had been used on the contact surfaces.

    Does anyone know what the original fuse lamps' used on the 490-T AC current rating was. I know that #47 lamps are rated at .15A but do not know the rating for the fuse lamps. I plan to get some LED replacements for the 490-T. It currently has one lamp that is soldered in and does a poor job of lighting the dial.

    Joe
     
  14. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

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    200ma to 250ma would be a fairly safe bet. I've had good results with 250's and no burn out's of the windings or excessive blow out of the bulbs.
     
  15. audmod01

    audmod01 AK Subscriber Subscriber

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    Larry;

    OK, thanks for the lamp data.

    I had exchanged some e-mails with Ron Ramirez about choosing a changer or turntable for this combination. I was thinking I needed to locate a unit that had a cuing lever to make playing records manually easier for my granddaughter. I knew I had a Techniques turntable in the barn but was dreading braving the 100 degree heat to walk out there and examine it. I walked into the study where I do all my work and spotted the ELAC Miracord 40A that used to belong to one of my aunts. I lifted the cover over it and there was a cuing lever staring me in the face. So now all I need to do is check the cartridge and needle and make sure the record changing feature works like it should. There will be no need to surf the internet for something suitable as I have something in hand. I am glad I had the discussion with Ron and it made me think to check everything I have.

    This is going to come together for probably under $1K even with purchase of wood, stain and lacquer or varnish if needed. It may be that the speakers are oiled walnut. If that is the case, the finish on an equipment cabinet will be even easier to do.

    Joe
     
  16. gadget73

    gadget73 junk junkie Subscriber

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    The Elac is probably a superior machine to the Garrards in all honesty. I always sort of wanted one, the pushbuttons make me think of old Chryslers or Edsels with the button transmissions.
     
  17. audmod01

    audmod01 AK Subscriber Subscriber

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    Gadget;

    I never had much experience with the Elac machines years ago. Perhaps that was because they were less subject to problems.

    Speaking of Chryslers with pushbuttons, I have a 1962 Imperial Custom, a four door hardtop design, which has the pushbutton transmission controls. Most people today do not recognize how to engage the transmission until told. This car sits now due my inability to work on it any more. It used to belong to a good friend who passed away back in the 1980s, so it has sentimental value to me.
     
    Last edited: Jul 23, 2017
  18. gadget73

    gadget73 junk junkie Subscriber

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    Sorry to hear about your friend but thats a very cool car. Google indicates it has a square steering wheel? Body style is very much like early 60s Chrysler stuff though. Not everyone digs them but I think they're cool. I like Edsels too though.
     
  19. audmod01

    audmod01 AK Subscriber Subscriber

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    Gadget;

    Yes the car has a rectangular steering wheel so that when driving straight, there is extra room for a person's legs to move about. The car has chrome bucket separated headlights that sit under the front fender eyebrows upon some posts down to the bumper area. The interior has lots of chrome trim around windows etc. I have a rear AC unit for the car that I never got around to having installed. The normal front AC will get the car plenty cool anyway - or at least it used to. It has sat for so many years now that the freon is probably all gone now. 129.5" wheelbase leads to a very roomy interior - plenty of legroom front and rear even with the front power seat all the way back. The driveshaft was so long that it has a center carrier bearing like long wheelbase pickups. Both front fenders and the sheet metal around the grille is stamped as one huge U-shaped piece of metal. There is about 1.5ft of space behind the grill in front of the radiator, so most wrecks do not damage the radiator. They were banned from demolition derby events many years ago because they were considered unfair competition. They usually lasted 5-6 meets before having to be retired.

    Best wishes always.

    Joe
     
  20. audmod01

    audmod01 AK Subscriber Subscriber

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    I looked up the Fisher listing for the dial lamps on the 490-T. Fisher P/N is 150082-7. The length of the slot these fit into measures 38.75cm or 1.6 inches. I just ordered some LED replacements from eBay which I may have to extend a bit to snap into the holders of the 490-T. These are 8V rated, but I doubt there will be any issue with using them on the 6.3VAC filaments of the 490-T.

    Joe
     

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