Bird Golden Eagle 2/15.......happy memories
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This page was last modified on Monday, July 26, 2010 20:28
1) History
I remember using one of these when I was a spotty teenager. We used to hire one (new shop stock) from the local music/radio/television shop for 10 shillings (50p) a night and then plug everything in sight into it. Whoever eventually bought it got the equivalent of an ex rep's cortina.
This one came from ebay and arrived complete with screw in legs (30 shillings extra) still screwed in and sticking out of the parcel. I wish I could remember who the carriers were because I'd use them again any day. What's left of the serial number reads F19984.
Instrument amplifiers were just a small part of Bird's activities and they don't seem to have kept up with the specialist manufacturers. What they did produce isn't particularly relevant today, but there aren't that many good examples kicking about and I was quite pleased to find this one. Nostalgia rules!
For an interesting run down of Bird and it's products visit Tim Fletcher and Steve Russell's site
Among other things you'll find a link to John Beer's visit to the Bird Organ Works in Poole back in the 60s.
To put prices into perspective, ten shillings then would be over a tenner now and forty one guineas is getting on for £900 (depending on who's figures you believe).
My apologies if I've pinched someone's scan of the catalogue, but I can't remember where it came from.
2) Overall condition is very good and it actually works. There are three main problems. First is the level of hum and noise. I've seen mention of hum on other sites and it may just be the way it's built. Someone's already changed the power supply caps so there goes the number one suspect.
Second problem is the fragile speakers. Although they're all fine at the moment, they're irreplaceable ellipticals by Elac with an odd five ohm impedance. Series wired, that gives the required fifteen ohms. I don't suppose the output stage would mind the odd four or eight ohm replacement, but even those are hard to find.
Third thing that definitely needs looking at is the power switch. The original push button contacts have burnt out (see picture below) and there's a replacement toggle switch hanging on the back panel.
I really haven't got time to do much with this one at the moment so the rest of this section is just for interest for the time being.
3) General views.
4) Below is the remains of the on/off switch. The right hand wiper arm has completely disappeared in a big bang.
I had another lucky find on ebay and came up with an almost identical replacement. It's an old Radiospares "Maka" Switch part which has the same moulding on a different mounting plate. The plate comes off and the moulding fits perfectly onto the Bird mechanism.
This picture shows The Radiospares mounting plate (left), the Radiospares switch mounted on the Bird plate (centre) and the old switch.
There's a small alloy casting which needs to be pressed onto the switch actuator. It's held on by spring action of the actuator and is a bugger to fit (but easy to drop).
Below is the new switch fitted into the front panel frame.
B****r it. Spoke too soon. The new switch works back to front, i.e. it's off when pushed down and on when up. I took it apart again and it's the same switch with a slightly different configuration.
If you look carefully, the paxolin contact carrier on the right is upside down and it's not possible to reverse it without dismantling the switch.
I'm not suggesting that anyone else actually tries this but somebody's got to, so here we go.
Take out the spring and W plate. The wire holding it in will probably break but it can be replaced with part of a paper clip. Drill out one of the rivets from the back with a 2mm drill bit. Parts will fly everywhere so it's best done on a spread-out cloth. Now remove the paxolin and turn it over. The two mushroom shaped contacts are loose and need to be removed and repositioned with the larger part underneath. Keep as much of the grease as possible.
Reassemble the switch and replace the drilled out rivet with an M2 screw cut to length and a nut. When it's tight, secure it with a small amount of solder around the nut. Job done.
5) Schematic.
This is as far as I've got with the documentation. Notice that there's no 110volt mains option. The mains wiring on this example had been modified but I think the fusing and voltage selection in the neutral line instead of live is probably correct. The external fuse and the voltage selector panel would be an accident waiting to happen if they were live.
If anyone's got an original I'd appreciate some confirmation on that.
This amp has a few differences to the circuit diagram I found on the internet, particularly around the bass control and the tremolo oscillator. R11, the odd combination of resistors in the oscillator feedback circuit, may have been tuned during test but I'm really not sure. Anybody know?
More soon.