Fisher Futura f-58 1963 680a amp for stand alone

this is my first Fisher and i was excited to have it , but now im wondering if it will be worth it..i have this amp and the schematic for it. my question is what is needed to make it a stand alone amp. i have heard that there is one tech here that redid his and sold it to another guy as a stand alone amp....HELP me find him so i can see if he has any notes as to what he had to do to it to make it a stand alone amp...also with the cost of 7591 tubes now days, is it possible to use 8417 tubes or 6l6cg tubes. i do not do the work and have a tech that did all the McIntosh repairs for years and now has his own shop and ill be asking him to do this work unless it will be very costly. if it is to much to do it ill sell it... thank you guys...

no and no on the tubes. Both are drastically different. What does work is changing the sockets so it will use 7868 tubes though. For all intents, they are the same tube, just with a different socket. If you don't have a very tight chassis (and I know zip about this one), Electro-Harmonix makes a 7591 for a not unreasonable cost that is decent. Its just a big fat thing compared to the old 7591 tubes. Their 7868 however is the correct size, which is pretty much the same size as a vintage 7591.

Does it actually need new outputs though? Frankly unless the old ones are done, I'd run them until they are.

there are no tubes with this unit

That looks like the EH ones will fit... plenty of room (you should see my Sherwood S-5500 - the EH 7591s are touching.)

The 680 needs a large power resistor to be added to work stand-alone - the preamp tube heaterss on the tuner chassis served as the common cathode resistor.

thank you tom i did find that in a post and made copy of it..ill give all info to my tech and await his opinion...

These two posts should have more than enough information on modifications required in order for the 680-A amplifier to be stand-alone. The first deals with signal path changes / stability changes, while the second deals with power supply and bias changes needed to run the amp without the preamp.

http://www.audiokarma.org/forums/showthread.php?t=459547
http://www.audiokarma.org/forums/showthread.php?t=461654

Don't bother changing the amplifier to 7868 tubes - the Electro Harmonix 7591 tubes that AES (among others) carries should be just fine space wise, and they sound pretty darn good as well.

-D

derekva said:

These two posts should have more than enough information on modifications required in order for the 680-A amplifier to be stand-alone. The first deals with signal path changes / stability changes, while the second deals with power supply and bias changes needed to run the amp without the preamp.

http://www.audiokarma.org/forums/showthread.php?t=459547
http://www.audiokarma.org/forums/showthread.php?t=461654

Don't bother changing the amplifier to 7868 tubes - the Electro Harmonix 7591 tubes that AES (among others) carries should be just fine space wise, and they sound pretty darn good as well.

-D

Click to expand...

I aquired a 680a several years ago. I sent it to Paul Gryzbek (Buzzybee) RIP for a rebuild and conversion to stand alone operation. My solution to the PS problem was to have the amp converted to run EL34 tubes instead of 7591. He also added a few dropping resistors to the PS. His comments upon completion were that the amp was cabable of about 20-22wpc, with a surprisingly wide frequency responce. However, the bias circuit would need substantial modifications if I wanted to take full advantage of the EL34 vs 7591.

In use the amp has proven to be very reliable and cool running. Sound is smooth and relaxed.

Nice amp overall.

Hope this helps.

Best,

Ross

Hey all,

Hope you don't mind me breathing some life into this old thread but I just picked up a 1963 Fisher Futura Anniversary Edition Italian Provincial (think I've got that right) console. This one comes with the 3 x 12AX7 Space Expander Spring Reverb unit as well. Unfortunately, the feet were broken off during a previous move but as I'm likely going to convert this to standalone, I don't think I will bother making new ones. Anyway, long story short, I was able to get this by no small measure of moving mountains and treading high water just days before Christmas and before the seller left back to the UK. He had originally bought it to have in his living room but the wife wasn't a fan so his loss, my gain. He had listed it for $650 Canadian on Facebook Marketplace which was a bit too rich for my blood with the holidays right around the corner but I decided to watch it and when he suddenly dropped the price to $50, I jumped on it and gave him $100 and long story short, now have it in the parking stall.

After some frustrated tinkering and confusion, I got it up and running last night (that auto off switch is sneaky) and wow, this thing sounds fantastic! I'm very impressed. And I honestly wasn't expecting much from the speakers but have to say, they surprised me as well. Very open and lifelike. The whole system has a sort of intimate presence to it that I could get used to in a hurry.

But all that aside, I do have a question in all of this. When I power it on, there is no indicator that the preamp is actually working Any lights or tubes that might light the tuner display are dark. And although the power amp section lights up, only one of the preamp tubes visibly lit up with the others all being cold to the touch. I pulled the tubes and they all tested strong on my Eico 625 tester.

So why would the signal still be coming loud and clear through the Aux input of the preamp if it is seemingly not working? When I plug my phone into the power amp input, it still puts out sound directly to the speakers although perhaps just a little less sweet overall. Not sure if it's my ears playing tricks on me or if that preamps stage does have that extra little bit of sweetness to it.

Clearly I have nowhere near the knowledge of some of the people who have commented in this thread but I'm honestly a bit perplexed by this. I'm going to be working with David Yee here in Vancouver to convert it over but just thought I'd check here first as the many AK threads on this unit have been a wealth of information.

Any thoughts on why the preamp would seem to not be working but still put out sound?

Thanks in advance. Will post some pictures later.

I finished converting a 680-A to Stand Alone last week. This thread might help your tech:
https://audiokarma.org/forums/index...-a-converting-to-stand-alone-question.971194/

I've been listening to this amp and it's becoming more pleasant as the new components break in.

I thought about employing the unused heater supply (originally intended for the tuner chassis) to "buck" the 680-A's primary down 6VAC but the power in my neighborhood rarely gets above 120V, in the summer it's often 115VAC.
I also thought about inserting a CL-80 in the Mains' primary to slow the warmup time (because the 680-A uses solid state rectification), but I haven't decided if there's any "real" benefit.

When I power it on, there is no indicator that the preamp is actually working Any lights or tubes that might light the tuner display are dark.

Click to expand...

The wiring harness I removed had a pilot lamp. Any chance your pilot lamp is blown or missing?

1st off the tuner & preamp are combined. Pull the knobs on the front face, remove the front face by removing the 2 or 3 screws on the sidewall facing the turntable. Then lift that side slightly and slide to the right(toward the turntable). Once the left edge clears the slot, move it straight up. The front of the tuner / preamp is exposed. There will be 2 tubular(Im having a brain fart for their names right now) lamps on either end. Test with an ohm-meter. They should light up when powered up. The Pilot lamp is a 1847 or 47 bulb. 47 or 1847 are cheap and plentiful.

Your phone has a hot enough signal strength to power the amp. The difference you're hearing is Solid state vs. tube (preamp). Clean all the tube pins and sockets with DeOxit sprayed on the pins then insert and pull 10-15 times. Wipe off the pins and re-insert. You won't short anything. Re-test in all regimes (AM-FM-AUX-Phono-Tape Monitor) you may need to spray all the pots and switches with DeOxit and exercise them back and forth some 25-30 times vigorously. Per your post, Obviously your preamp is working if you're getting sound, you're just not getting any visual cues. (Replace the lamps). You can use LED's that are custom length (measure from center to center of the clips for the lamps). Not sure if the tuner is powered ON or is off when the selector switch is in any other position than AM or FM. Check the tubes again with it in each position and leave it in that position for 1-2 minutes. See if the tubes heat up or light up. Some will not show a lot of light (6BA6, 6AU6 or 6BE6 are the tuner tubes). 12ax7's(should be 4 of them, 2 for phono, 2 for preamp) can vary in light output by manufacturer. It depends on how much of the heater filament is exposed. On the 12ax7 you can meter DC or AC voltage between pins 4 & 5(6.3V), or 4&9 and 5&9.(6.3V on each leg).

Suggest strongly you get the Service Manual @ www.Fisherconsoles.com. http://www.fisherconsoles.com/futura IV.html

heyraz said:

I finished converting a 680-A to Stand Alone last week. This thread might help your tech:
https://audiokarma.org/forums/index...-a-converting-to-stand-alone-question.971194/

I've been listening to this amp and it's becoming more pleasant as the new components break in.

I thought about employing the unused heater supply (originally intended for the tuner chassis) to "buck" the 680-A's primary down 6VAC but the power in my neighborhood rarely gets above 120V, in the summer it's often 115VAC.
I also thought about inserting a CL-80 in the Mains' primary to slow the warmup time (because the 680-A uses solid state rectification), but I haven't decided if there's any "real" benefit.


The wiring harness I removed had a pilot lamp. Any chance your pilot lamp is blown or missing?

Click to expand...

Thanks for this. I went downstairs today, popped in the tubes and lo and behold, both lights turned on and everything seemed to be working fine.

So just curious but what are you using for a preamp? I really like the sound of the preamp on this unit but don't know if I really need the whole tuner section and whatnot. I'm working with a good tech and tube amp designer here in Vancouver so I may have him build a smaller preamp that pairs well with the 680-A.

larryderouin said:

1st off the tuner & preamp are combined. Pull the knobs on the front face, remove the front face by removing the 2 or 3 screws on the sidewall facing the turntable. Then lift that side slightly and slide to the right(toward the turntable). Once the left edge clears the slot, move it straight up. The front of the tuner / preamp is exposed. There will be 2 tubular(Im having a brain fart for their names right now) lamps on either end. Test with an ohm-meter. They should light up when powered up. The Pilot lamp is a 1847 or 47 bulb. 47 or 1847 are cheap and plentiful.

Your phone has a hot enough signal strength to power the amp. The difference you're hearing is Solid state vs. tube (preamp). Clean all the tube pins and sockets with DeOxit sprayed on the pins then insert and pull 10-15 times. Wipe off the pins and re-insert. You won't short anything. Re-test in all regimes (AM-FM-AUX-Phono-Tape Monitor) you may need to spray all the pots and switches with DeOxit and exercise them back and forth some 25-30 times vigorously. Per your post, Obviously your preamp is working if you're getting sound, you're just not getting any visual cues. (Replace the lamps). You can use LED's that are custom length (measure from center to center of the clips for the lamps). Not sure if the tuner is powered ON or is off when the selector switch is in any other position than AM or FM. Check the tubes again with it in each position and leave it in that position for 1-2 minutes. See if the tubes heat up or light up. Some will not show a lot of light (6BA6, 6AU6 or 6BE6 are the tuner tubes). 12ax7's(should be 4 of them, 2 for phono, 2 for preamp) can vary in light output by manufacturer. It depends on how much of the heater filament is exposed. On the 12ax7 you can meter DC or AC voltage between pins 4 & 5(6.3V), or 4&9 and 5&9.(6.3V on each leg).

Suggest strongly you get the Service Manual @ www.Fisherconsoles.com. http://www.fisherconsoles.com/futura IV.html

Click to expand...

Thanks so much. I've read a lot of your replies in all of these Fisher console/standalone threads and you really know your stuff.

I need to pick up some Deoxit but in lieu of that, I did put all the tubes back in today and when I fired it up, both lights were working. There is definitely a bit of an underlying crackle that underpins the music at lower levels but I think this preamp schematic might be a bit above my current pay grade so am not sure what might be causing it.

All of that being said, when you reference solid state vs tubes, ie power amp vs preamp, do you just mean that the poer amp has a bit more grunt to it so is more akin to solid state with the grace of the pre being more tube-like?

Finally, I really like he sound of these speaker drivers. They are labeled Fisher Speaker Division and seem to have large Alnico magnets on the back. Any info on these? Am thinking I will mount then in a new enclosure and may keep them as well.

Crackle can be heating up of dirty socket leaves, caps that are heating up or even solder joints that are expanding under heat.

I was comparing Comparing the phone (Solid state) to the unit's preamp (tube). The phone has minimal to no EQ curves for tone control, and no real grunt as it's mainly designed to power it's amplifier (less than a watt) or earphones (in the mW range). So it can sound tinny, and or flat.

Fisher had a Speaker division based in Belleville N.J. They generally made pretty decent drivers. And yes those are Alnico magnets. They aren't JBL grade, but for the money pretty darn good. This division was wholly owned by FISHER RADIO Co. and had nothing to do with United Speaker owned by Bill Hecht, which made most of if not all the XP series speakers in the 60's for Fisher.

Thanks for this. I went downstairs today, popped in the tubes and lo and behold, both lights turned on and everything seemed to be working fine.

Click to expand...

In addition to spraying/treating the tube sockets, switches and potentiometers... I think you should also clean the "To Speaker Switch" and "To Tuner Chassis" connectors on the 680-A chassis.

So just curious but what are you using for a preamp?

Click to expand...

I bought the 680-A and 680-T chassis as a set with original tubes years ago for maybe $500. I never seriously intended using the Tuner/Preamp section, I just wanted to hear what a 7591 amp sounds like.
My impressions: The 680-A is loud, clear and powerful.

Having used many preamps (tubed and solid state) over the years, I've settled on an Audio Research LS-7 Line Stage and an Audio Research PH-3 Phono Preamp. I've been very happy with that combination for years, no matter what power amp they've been paired with.
I use a Magnum Dynalab MD-90 tuner.

I donated the 680-T chassis to an AK member.

larryderouin said:

Crackle can be heating up of dirty socket leaves, caps that are heating up or even solder joints that are expanding under heat.

I was comparing Comparing the phone (Solid state) to the unit's preamp (tube). The phone has minimal to no EQ curves for tone control, and no real grunt as it's mainly designed to power it's amplifier (less than a watt) or earphones (in the mW range). So it can sound tinny, and or flat.

Fisher had a Speaker division based in Belleville N.J. They generally made pretty decent drivers. And yes those are Alnico magnets. They aren't JBL grade, but for the money pretty darn good. This division was wholly owned by FISHER RADIO Co. and had nothing to do with United Speaker owned by Bill Hecht, which made most of if not all the XP series speakers in the 60's for Fisher.

Click to expand...

Ah, ok. That makes perfect sense. Wasn't able to go get deoxit as we had an unexpected snow day but will head out for that tomorrow.

Thanks again, I have a feeling I'll be back with more questions for you soon : )

heyraz said:

In addition to spraying/treating the tube sockets, switches and potentiometers... I think you should also clean the "To Speaker Switch" and "To Tuner Chassis" connectors on the 680-A chassis.

I bought the 680-A and 680-T chassis as a set with original tubes years ago for maybe $500. I never seriously intended using the Tuner/Preamp section, I just wanted to hear what a 7591 amp sounds like.
My impressions: The 680-A is loud, clear and powerful.

Having used many preamps (tubed and solid state) over the years, I've settled on an Audio Research LS-7 Line Stage and an Audio Research PH-3 Phono Preamp. I've been very happy with that combination for years, no matter what power amp they've been paired with.
I use a Magnum Dynalab MD-90 tuner.

I donated the 680-T chassis to an AK member.

Click to expand...

Thanks again. I think building a dedicated pre with David Yee here in Vancouver will be the way to go.