Fisher 50a mono amp data

Im sure any of the AKers that own these amps have been following my latest build of my fishers after aquireing a pair finally.Ive had a week with my refurbished pair and after a long journey in audio these will NOT be sold.The quality of sound reproduction I have with the 50a's is astonishing.Now,i touched on asking current owners to post there Fisher 50 a serial numbers so we can get a fair handle on what survivor amps are still out there in use today.It would be great to have this info SO... serial no. on my amps are..
Fisher 50a
serial no. 734 -5v4[2]..1614[6cl6gc] [2]..6cl6[2]..12au7[3]
serial no.1286 -5v4[2]..1614[6cl6gc] [2]..6s4[2]..12au7[3]

Darn nice amps, if I ever go mono blocks I think these would be the cats meow...rarer than rare...

I m fairly sure there at least 2 other Fisher 50a owners on this site.Maybe there aren't as many total owners as I suspected..oh well,mods you can junk this tread
Hunter00

I think there were a couple for sale at the auction site last week, so maybe you'll have some company soon!

Dave

Dave you asked about my impressions of the fisher 50a's after the newness factor wore off.Ive been putting the amps thru the paces to make sure no problems creep up so they have been run approx. 4-8 hrs per day the last week .
They have been very stable over-all,holding bias,no red plateing of tubes and the transformers have been no more than warm to the touch even after long hrs of play and at fairly high volumes.
Now for the sound.When I went to pick them up from my tech cris he was quite excited.He explained to me he had not heard an amp ever image the way the fishers were thru his speaker.They seem to somehow project the soundstage out into the room and flood the listening area.He runs a vintage pair of big cabinet EV's .
We spent the afternoon going between my fisher 50a's and his refurbished Marantz v tube amp.The fishers detail and separation of stereo content is the best I have ever heard.We were both hearing sutle content in the music not heard before.
When I got the fishers home and set up in my system I was further impressed on my Electrovoice interface D speakers.
The amps were ran with a modded dynaco pas 2 preamp.Ive been spinning records as well as listening with cd as source.I have a particular cd {BB King & eric Clapton riding with the king}advanced resolution audio that sounds incredible on my Dynaco mkiv mono's and with the fishers it was nothing short of amazing to listen to,guitars,horn instuments and particulary voices ,sounds like you are there at the live performance.
These amps have a lot of jam as well,no shortage of clean power
So to recap these are the best amps ive personally ever listened to and im very happy to have them,there fairly rare and just plain cool to look at as well with there big a_s OPT's and all the tubes lit up at night.
To think these are 60 yr old amps!

Thanks for the write up. :thmbsp: :thmbsp: :thmbsp:

Now do not post your address or telephone number: by the end of the summer my wife is going to want to kill you!!!!!

LOL,I guess im lucky my wife of 25 some-odd yrs has the audio GENE!she buildt up a lot callus to my climb in audio gear since around '84 and can appreciate quality sound as well.

Thanks for supplying your impressions -- and so glad they are working well for you now!
They are truly a unique design -- I can think of no other design like them every made --

Dave

Posting information from your other thread would help put this in context. I've included it below.

For the record, my Fisher 50a amps are as follows:

2176 uses 5v4 and 6cl6 tubes, 507-123 interstage transformer

25955
26762
26910
57459 all four use 5aw4 and 6cl6 tubes, 507-123 interstage transformer

Originally Posted by TheRed1 View Post
Beyond the additional Z-Matic circuitry of the AZ version, the driver stage is also significantly different. The 50-A used 6S4 versus the 50-AZ's 6CL6's. To make it properly confusing, it should be noted that there were multiple versions of the 50-A and possibly multiple versions of the 50-AZ, too.


In summary, the 50-A was produced for two model-years, 1953 and 1954. The 50-AZ was produced for the 1955 model-year and still available into early 1956. Of the 50-A there were AT LEAST three versions: the 50-A (-1), serial numbers 0001 (?) thru 1500; the 50-A-2, serial numbers 1501 thru 3000 and the 50-A-3, serial numbers 25,001 thru 26,000 (?) as well as 26,501 thru 27,500. There may have also been a 50-A-4, serial numbers unknown.

Perhaps if those lucky enough to have 50-A's or -AZ's could post their serial number along with a description, it might be possible to piece together a chronology of design changes. That is, assuming we can filter out the subsequent conversions and other alterations . . .

For the 50-A interstage transformer, (Fisher part no. 507-1104,) Sams gives 586Ω CT .050A for the primary and 1.52KΩ for the secondary. The 50-AZ uses a different transformer, (Fisher part no. 507-123,) for which no specs are listed. All of the other transformers are the same in the 50-A and 50-AZ.

Also, I just noticed the Sams 50-A service manual lists both 5V4G and 5AW4 rectifiers in the data box on the cover sheet. I guess we can conclude Fisher changed over to the new tube before the introduction of the Z-matic version. The Sams does not show any changes to the power supply circuitry associated with the tube change but the schematic illustrates the earlier 5V4G's and does not mention alternative 5AW4's.

Click to expand...

Fisher 50 AZ here

57639 T507 123D (IT)

5AW4 rectifier - 6CL6 driver

Thankz guys for your participation!
Since these amps are new to me Im interested in knowing your opinions of the 50a's,brief description would be great{I know mine was long winded but im quite excited by there aquasition!!}.To get a handle on how many survivor amps would be cool,as I cant find any info on totals produced.
Any other owners out there of this fabulous early Fisher Triode Mono amplifier??

hunter I have the 3rd and last evolution of the 50as. 200as the other is the 55a. I completely understand your excitement with your 50s. theres no doubt I have found the last amps I will ever need. if you find a copy on vinyl riding the king is much better than cd. enjoy

Thx stltrains,If you could take the time to post you SN's and a pic would be nice as well.
I will keep my eyes open for that title in vinyl.
Hunter

Latest mods ..Newly added rca's,on/off toggle switchs and power on led lights

hunter00 said:

Latest mods ..Newly added rca's,on/off toggle switchs and power on led lights

Click to expand...

I'd like to see these but the pic you posted is extremely tiny. :sigh:

Ohighway said:

I'd like to see these but the pic you posted is extremely tiny. :sigh:

Click to expand...

The on/off switches were installed to the extreme left side /front face of the chassis's centered and if you look carefully you can see the flush mount lcd lights glowing near the bias adjust openings.
The one amp I had to upgrade the binding posts on as the old were poached.
The new gold rca's are a huge upgrade over the stock ones which were well worn and wouldn't hold a interconnect cable head.
I will post close up pics soon
Hunter

I experience a fair amount of hum with the original rca's,and as I said the interconnects floated inside the rca's in each amp as they were worn and looked original eq.These had to be replaced and I didn't like having to power the mono's on with a power bar,hence the on/off switch mod,then I figured it would be cool to have a functional power on light installed as well.
Was hard to take them out of the system for the upgrades,put my dynaco mkiv monos in there place and as much as I luv my mkiv's they sounf thin compared to the Fishers...

The Fisher 50a's complete

Heres a few pics of the 50a fisher mono amps back home after the new rca's and power pilot lights installed,was going to paint the OPT/Power Tranys but figured they look best with the piteena on them,hell there 60 yrs old!
Also installed new bias pots on both amps and fab up a guitat plug for my multi metre to keep an eye on bias...there good to go for many yrs enjoyment!!
Hunter

Well I finally had time to get to my storage a pull out my 1964 Braun L-1000 studio monitors and hook them up to the fisher 50a's.
The brauns were my best set of speakers in my collection but the little lady doesn't like the looks as much as the wood veneer on the EV d's.,just hooked them up to the mono amps and they are truly the best speakes ive heard to date.

Nice job Hunter, darn nice amps and am jealous lol Someday I might own a couple mono blocks. Also heard the 30-A's were worth having as well... Al