TheRed1
Console Conservationist
Among the many new Fisher console manuals Jon has recently uploaded to the Fisher Consoles website are the 1960 Custom Electra III (model 440) and the 1959 Stereo Companion (model 560). This new information finally sheds some light one of Fisher's quirks: the 2.5Ω ONLY transformers found on some 30-A amps and seemingly all of the 610-ST (and 510-ST) chassis.
***A big 'Thank You' to Jon (aka: Jonboy55) for all the work he has put into making both service and owner's manuals for Fisher consoles available.***
Below is the speaker schematic for the Custom Electra III:
It shows 3 presumably 8Ω speakers connected in parallel which would have an impedance of approximately 2.5Ω. It even states that both L & R speakers are identical. What continues to baffle me is that the 30-A's that comprise the B channel in all the CE IIIs I have seen have all been of the 30,000 series with the 4, 8 & 16Ω taps. I guess the 4Ω taps would be close enough. It's just odd that that Fisher didn't use the 10,000 series 30-As which were almost an exact match for the amp in the 510- and 610-ST's
Here are the three different series of 30-A's used in the model 560 Stereo Companion:
10,000 Series 30-A
20,000 Series 30-A
30,000 Series 30-A
Below is the amp section of the 610-ST for comparison. Note the similarities to the 10,000 series 30-A's. There are only two minor cap value differences: C61 (which is C2 on the 30-A) on the the 610 is 150µµƒ, 500V but 100 µµƒ, 1000V on the 30-A, and C62 (which is C5 on the 30-A) on the 610 is 24 µµƒ, 500V but 150 µµƒ, 500V on the 30-A.
Another odd thing I have noticed is that Fisher's serial numbers appear not to have been issued entirely chronologically. The 30-A in my 1959 560 has a higher number than the 30-A in my Sister-in-law's 1960 CE III.
I opened up the speaker compartment of my 560 for the first time today to see how its speakers were connected. I had previously thought that it had 3 identical 8" speakers. Now I see that the bottom one has a larger magnet and a different part number. Would that be the woofer? These are wired in parallel, too, but without any sort of crossover circuitry - not even a filter cap like the one on the CE III's tweeter.
***A big 'Thank You' to Jon (aka: Jonboy55) for all the work he has put into making both service and owner's manuals for Fisher consoles available.***
Below is the speaker schematic for the Custom Electra III:
It shows 3 presumably 8Ω speakers connected in parallel which would have an impedance of approximately 2.5Ω. It even states that both L & R speakers are identical. What continues to baffle me is that the 30-A's that comprise the B channel in all the CE IIIs I have seen have all been of the 30,000 series with the 4, 8 & 16Ω taps. I guess the 4Ω taps would be close enough. It's just odd that that Fisher didn't use the 10,000 series 30-As which were almost an exact match for the amp in the 510- and 610-ST's
Here are the three different series of 30-A's used in the model 560 Stereo Companion:
10,000 Series 30-A
20,000 Series 30-A
30,000 Series 30-A
Below is the amp section of the 610-ST for comparison. Note the similarities to the 10,000 series 30-A's. There are only two minor cap value differences: C61 (which is C2 on the 30-A) on the the 610 is 150µµƒ, 500V but 100 µµƒ, 1000V on the 30-A, and C62 (which is C5 on the 30-A) on the 610 is 24 µµƒ, 500V but 150 µµƒ, 500V on the 30-A.
Another odd thing I have noticed is that Fisher's serial numbers appear not to have been issued entirely chronologically. The 30-A in my 1959 560 has a higher number than the 30-A in my Sister-in-law's 1960 CE III.
I opened up the speaker compartment of my 560 for the first time today to see how its speakers were connected. I had previously thought that it had 3 identical 8" speakers. Now I see that the bottom one has a larger magnet and a different part number. Would that be the woofer? These are wired in parallel, too, but without any sort of crossover circuitry - not even a filter cap like the one on the CE III's tweeter.