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87.60.37.138
On my way home, I spotted a cabinet in a container that turned out to be pretty heavy. (The cabinet, that is.)
It seems to be a mono-amplifier that has been in the closet for quite a few years.
There's a sign with "Bang & Olufsen" "Supplier for the royal danish court".
This is a well known danish audio company, existing this very day.
Allright, the metalcabinet has 2 modules that can slide out by releasing 4 screws on each.
One is an input section without tubes but a selector and 4 pots, the other one is apparently an amplifier with 4 tubes.
An ECC83 from Telefunken and one from Siemens and - drumroll - 2 GEC KT88.
Actually there are 5 tubes, since it also has a "magic eye" for
My guess is that the amp is for 220 V and could be plugged right in, as I have measured my voltage to 225 V - but.... is this healthy and should I see to, that a loudspeaker is attached first? Which impedance? Another little label says "Output 60 V".
I have heard that a variac should bring up voltage slowly, but have no idea how to do that.
Hmm, there are 2 inputs labeled "Fotocell". Any idea of what that is for?
If anyone can help with info and advice, I will be very greatfull.
Thank You in advance.
Ole
Copenhagen
I have added some pictures AND a diagram of the poweramp. Pls. browse the jpg's - and disregard the 2 fishing-pictures.
I didn't approach this very smart, because I found some info on a danish homepage. Still I hope for Your kind help regarding som questions.
Picture BOFA V60 pre1:
What are the round things in the top of the picture? Some wires are soldered to each. Looks like capacitors and then again not.
I can inform that the two squares to the right are small encapsulated trafo's. For microphone input?
There's a lot of components soldered to the circuitboards, but it is hard to take a good photograph.
BOFA V60 main3:
What is the other setting for? The technical ones might deduct this from the diagram "v60 diagram".
BOFA V60 main2:
What can I say? This module alone weighs in at 9,5 kg. There is a power cord for 220 Volt connected to the chassis, soldered to two of the pins in the 12 pin plug.
You can see the "magic eye" as well.
If anyone can tell me anything interesting from these jpg's and the diagram, I will be very thankfull.
Now for the info I allready have found:
The real name of the amplifier system is BOFA, which was an industrial sound sub-company of B&O. It was started in 1927 and finally sold to The Philips International Group in 1971, who ran the company for some years after that.
BOFA manufactured primarily sound and light-systems for Cinema's and Movie-theatres.
The amps came in model V15, V40 and V60, where the number tells the output in watts of these mono-modules.
They were considered extremely rugged, highly reliable and with state of the art sound. This is to be considered related to the construction year, which is 1959 for the V60.
In my hometown, the local cinema used V60's until 1991, where they were upgraded to Italian transistorized amps with much higher power and, according to sayings, a quality that was a step or two down from the V60's.
The amps were paired with loudspeaker-systems, often consisting of open baffles with 3 bass-speakers and 1 mid/treble horn. The matching impedance of the loudspeakersystems should be 20 ohms.
Thank You. Hoping for some comments and insight.
Regs
Bang & Olufsen" is
This is a well known danish audio company, existing this very day.
You are absolutely correct.I have 3 of their linear tracking turntables which I adore..They are so quiet and rumble free and I can tap anywhere on the base of these tables while a record is playing and I can't hear one hint of microphonics,feedback,or rumble in the speakers.In the US,B&O is very popular.Bose is a joke next to B&O for quality AFAIC.
Now you made a very nice find..If that has the Lundahl transformers or the equivalent,I would find a mate and have a killer second or even first system.I have a feeling thats a wide bandwidth amp knowing B&O and their standards.
If the power supply waveform isn't pretty,neither is the sound in most cases.
As others have pointed out , it is probably a commercial unit although it is most complex as it seems to have a phono input as well as mike inputs If there is no circuitry ( live, that is ) in the input module then it must have been dependent on the in the input devices having their own preamps and the input module serving as a line switcher,
Don't know about the 60 volt output but many commercial amplifiers have a 70 volt output for commercial speakers and thus need a matching transformer for normal impedance speakers. You may want to take a closer examination of the output transformer, however. Most US commercial types have various taps in order to run normal impedance speakers. Being tha B&0 is still around they may have the specs still for the output transformer.
As with any vintage amplifier most likely any electrolytic caps will be shot. You do not mention any rectifier tube so I am assuming that the the unit has a solid state rectifier, but please check carefully as some theater amps in the US had separate power supplies, separating the B+ and filament circuitry from the actual signal amplifier circuitry.
A photo of the internals would be helpful, although I doubt if many of these Euro type commercial units ever made it to the US.
Stu
I will gladly provide some photos of the internals. Will wait 'till tomorrow, for better ligth.
You are right about the solid state rectifier, as well as a mains transformer, and a series of 600 V, 32 microF capacitors.
Also an encapsulation that holds ?? the output transformer maybe.
And a 2-position switch with a sign saying 100V, 20 Ohm.
Thank You so far.
He should measure the 60V output. If it's as I suspect, it might be 60VDC to power the exciter lamp for the soundtrack.
My fault - it is the version of the amplifier, V60. I thought it meant 60 Volt.....
There is no 60 V output as such. The only output is one loudspeaker terminal, DIN-type (a flimsy one), labeled "Hojttaler" which is danish for loudspeaker.
Then the brown/red knob on the front would be a security circuitbreaker? It is connected in series with the power switch.
Finally I'm having the idea, that the line unit could be a passive selector/mixer, since there are 2 pots labeled Reg1 and Reg2, that could correspond to the 2 microphone and 2 lightcell DIN input-terminals? Maybe...
Will post pics of internals tomorrow.
Thank You so far.
I assume you were dumpster diving?
I just got a 3ghz Pentium D dual core with 1 gig of DDR2 ram and a SATA 2 200gig hard drive.
Love those dumpsters!
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
And a picture of the inputs.
I have a picture of the front as well.
Sounds like it could be a film projector amplifier.
Ahh, that would be the photocell input, I guess?
regs
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