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Fisher 50-C-3 schematic

kkib

kkib

Member
I just received a second Fisher 50-C-3. I brought it up slowly on a variac. It powers up but all I am getting is a very faint signal which does not increase when I turn the volume control.

I have schematic for 50-C but I am not sure if it's the same for 50-C-3. Does anyone have a schematic which is labeled for 50-C-3?
 
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Below is the 50-C-4 schematic. I think the reason there are so many iterations of the 50-C was simply Fisher trying to keep up with the record industry's rapidly evolving EQ standards of the early 50s. The original 50-C had 4-position lever switch with LF turnover settings for AES/NARTB/LP/800 and HF roll-off settings for 0/8/12-AES/16-NARTB. Note the 5-position switch on the 50-C-4 and how it was labeled:

50-C-4Faceplate.jpg


There was probably yet another version in 1954, (after the 50-C-4,) with RIAA labeled positions. How many positions and what are they labeled on the 50-C-3? Unless you wanted to be super authentically historically accurate you would probably want to dedicate one position for the RIAA settings and use the appropriate component values to approximate that curve.

50-C-4Schematic.jpg
 
I had never heard of 50-C-4 before. Thanks for the schematic.

Both of the units have four settings and slightly little different writings. The unit with a later serial number has ORTHO added under one of the settings on the left and on the right.

I snapped a picture of them together.

50Cs_2.jpg
 
Fisher must have gone through the first three versions of the 50-C fairly quickly for them to have proceeded the introduction of RCA's New Orthophonic EQ curve.

From the March 1954 issue of High Fidelity:

The change [introduction of RIAA curve], at this late date, is a source of both annoyance and sly gratification on the part of preamplifier-equalizer manufacturers - they'll have to incorporate a new setting in their designs (most already have the setting, although not by the new RIAA-AES-NARTB title), which is irksome. On the other hand, they cannot help being glad that some millions of microgroove records, requiring varied equalization, have been issued before uniformity prevailed. As Manufacturer Avery Fisher says, "People will be needing equalizers for some time yet." Presumably, few people will throw away their old disks.
Click to expand...

Very interesting that HF got their quote on this development from Avery Fisher himself. Perhaps he was seen as the one capitalizing the most on the record industry's idiotic standards wars with his always up-to-date 50-C. I think the 50-C probably deserves its iconic status as a contender for starting the trend toward hi-fi components.
 
And in keeping with the 50-C's iconic status, anyone care to guess who produced a near exact copy of the 50-C design -- so obviously so that surely permission must have been granted for its production?

Dave
 
No other takers, eh? If nobody gets this right by this evening, I am going to consider the collective Fisher Forum officially stumped!

Dave
 
Nope. But I gotta tell ya, there's gonna be a lot of folks drop their jaw when they find out! Thanks for at least trying! Everybody else must either be really stumped, or just wannabees! :)

Dave
 
OK. Since I know you're all waiting with abated breath, and since all the usual suspects have either given up or gone to bed, I'll fill you in on the answer to my question. But first, some clues:

1. It's butt ugly.

2. It's a styling nightmare.

3. It doesn't even have a power light to let you know when it's on.

4. Like a Model T, you can get it in any color you like, as long as you like gold.

5. Typically, you can't give one away, even if you wanted to.

6. Somebody will usually pay you to take one home from a hamfest.

7. It's butt ugly.

So what do you get when you take a beautiful Fisher 50C preamp, remove the power supply, remove the loudness control feature, add an umbilical cord for power, and put it all in the most homely looking structure man could possibly devise? You get.....wait for it......wait for it.........

YES, an honest to goodness real live Heathkit WA-P2!!!!!!!

Yes, you get it all, from the individual input level controls, to the individual Contour and Roll Off switches. You get the very same tube line up, in the very same circuit, with the very same component values as the famous Fisher 50C! Yes, you get the very same input array, the very same tone control action, and the very same sensitivity specifications as that of the 50C! And as an added bonus, you get to either build it yourself, or undo the mess someone else made when they tried to build it!
 
But wait! There's more! Well, no, there's not. The stupid computer just went ahead and posted my post before I was finished.

In all seriousness though, most folks have no clue that the basic circuits between these two preamps are literally one and the same. So, if you've ever had a hankerin to play around with a 50C, but find yourself with more month than income, just look through the boneyard of the next hamfest. Someone is sure to simply give one to you so they won't have to pack it back up -- again!

Dave
 
By design I thought you were also including its physical appearance - no fair!

The closest I could find in looks was Bogen's PR100. Heathkit was one of my guesses but I couldn't find anything with a similar control layout. One of my first thoughts was that someone might have offered it in kit form after it was no longer a current model. Do you know approximately when Heathkit introduced the WA-P2? Was it offered at the same time as the 50-C, 1953-55?
 
Well, I did say it was butt ugly -- and it is!

Carter, I would bet that the production of the 50C and the WA-P2 overlapped at least somewhat. The original Heathkit preamp WA-P1 was short lived, with the WA-P2 very likely offered with the later W-2M or early W-3M amplifiers, the second and third power amplifiers in the long line of Heath's W-xM line of mono power amplifiers. I will check when I get home tomorrow, but I would bet that the WA-P2 was certainly available by 1954. No doubt however, that the Heath version of the 50C was introduced when Fisher was already gearing up for the next preamp model in their line.

Dave
 
Hiya,

Well .. now the value of those is gonna go through the roof .. you let that cat out of the bag .. :)

Frannie
 
Carter -- As the resident historian, you were right on the money as usual. After investigation, the best I can tell, is that the WA-P2 was in fact introduced as a new companion to the new (at that time) W-5M power amplifier, that Heath brought out in 1955. That would mean that Heath was (obviously) given permission to produce the basic circuit of the 50C, AFTER Fisher stopped production of that series.

Also of note, the WA-P2 represents the original version of the 50C, most notably identified as having only four positions to each of the Roll Off and Turn Over EQ switches, whereas Fisher of course always upgraded their unit with more EQ options as the ever changing EQ landscape developed at that time. The sole advantage Heath had by its later introduction was that it labeled positions on the EQ switchs as "RIAA", rather than "New Ortho" as Fisher originally did in their first units.

Finally, one other huge difference between the Fisher and Heath editions, is that while Heath obviously stole power from their power amps to power the WA-P2 and therefore save costs for their version (the thing only cost $19.95 when introduced!), the WA-P2 also operated the tube heaters from AC, using a hum balancing pot to minimize noise. Of course, the built in power supply Fisher provided in the 50C provides DC to operate the heaters from, which gave the authentic version a serious edge in quiet operation.

It is so true how details can make or break a given product. Here are two units containing the same basic audio circuitry, but due to appearances and a built in quality power supply, one product flourishes on its own with high regard, while the other basically has to sell almost entirely by using what in essence amounts to a "buy a power amp, and get a preamp for free" campaign -- but due to such non descript looks and noisy operation, merits basically only a footnote in audio history.

Still, for those so inclined, a proper external power supply would not be hard to build, and there's plenty of talent here on AK to gussy up its looks, so for little more than junkbox parts, you too could have a 50C! Well, sorta anyway.......

Dave
 
Sorry to take this thread off topic (LOL) but,....

I am still looking for the correct schematic and the parts list for 50-C-3 . The one I have must be for the earlier version as it shows C2 (A) 500uF and C2(B) 500uf but the caps I have installed in the preamp are C2 (A) 1000uF and C2(B) 500uf.
 
It sounds like you're using the Sams from July 1953. C2 equates to C26 on Fisher's 50-C-4 schematic which specifies the same values as the July '53 Sams. It seems odd that Fisher would have increased the voltage for half of the filament supply cap on the 50-C-3 and then gone back to the original spec with the -4 version. Are you sure the cap is original?

I think it is likely the only things that changed over the first three versions of the 50-C were a few minor adjustments of resistor and cap values in the EQ section. I don't see any reason they would have had to mess with the power supply.
 
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