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Roberts Radio drone synth.

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Roberts Radio drone synth.

Postby Arpangel » Mon Mar 01, 2021 12:48 pm

Yes, not sure about this, mixed feelings, I’m disappointed that my 60’s Roberts isn’t working anymore, I had to buy a six quid PP9 to try it out, which was a bit of a pain, they are almost impossible to get.
However, all is not lost, it’s making some really nice distorted "filtery" drones, and it’s got a headphone out, so I’m sorted. If you turn the tuning knob, it acts like a filter, and at the same time the nature of the drone changes, I tried touching the circuit board inside too, and that produces some amazingly acoustic sounding crackles, like cellophane.
I’m going to experiment further, with some jumper wires and pots, this could turn out to be a really cool box, a use that Roberts definitely never intended it for.

:thumbup:
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Re: Roberts Radio drone synth.

Postby The Elf » Mon Mar 01, 2021 1:44 pm

I used to keep an old Ferguson radio for just this purpose! Now I use lots of 'found sounds', such as comets, car engines, bird song and ice floes...
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Re: Roberts Radio drone synth.

Postby jjlonbass » Mon Mar 01, 2021 2:01 pm

If it's not working, a likely cause is the AF11x series transistors fitted to UK / European radios from about 1961 to 1968. These transistors develop whiskers on the inside of the tin plated steel package and these cause short circuits from the case to the transistor die. Replacement exact or near equivalent transistors in a different package are available at a price.
Some '60s Roberts radios helpfully put these transistors inside modules with soldered down metal covers. These are a pain to repair.

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Re: Roberts Radio drone synth.

Postby Folderol » Mon Mar 01, 2021 3:38 pm

Depending on the precise layout, you can often 'cure' these by simply cutting the ground pin. I'd do that for a Hacker radio, but never for a Roberts - they ripped off Hacker, Dynatron and a few others with their case designs - at the time it never occurred to those companies that their appearance would be copied :(
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Re: Roberts Radio drone synth.

Postby blinddrew » Mon Mar 01, 2021 3:38 pm

That sounds like a really interesting box Arpangel. I'm tempted to go hunt through the garage to see if I've got an old radio kicking around somewhere! :)
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Re: Roberts Radio drone synth.

Postby Martin Walker » Mon Mar 01, 2021 5:39 pm

Some of this sounds suspiciously like circuit-bending Tony :ugeek:

Two words for you if you want to find out more: 'Reed Ghazala'.

Long may it continue!


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Re: Roberts Radio drone synth.

Postby Arpangel » Tue Mar 02, 2021 11:02 am

jjlonbass wrote:If it's not working, a likely cause is the AF11x series transistors fitted to UK / European radios from about 1961 to 1968. These transistors develop whiskers on the inside of the tin plated steel package and these cause short circuits from the case to the transistor die. Replacement exact or near equivalent transistors in a different package are available at a price.
Some '60s Roberts radios helpfully put these transistors inside modules with soldered down metal covers. These are a pain to repair.

John

It is exactly as you describe, the transistors are in the module, at the bottom of the board.
I’m torn, working ones aren’t much money, and this one is making some interesting noises, so I may continue with my circuit bending.

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Re: Roberts Radio drone synth.

Postby Arpangel » Tue Mar 02, 2021 11:06 am

Arpangel wrote:
jjlonbass wrote:If it's not working, a likely cause is the AF11x series transistors fitted to UK / European radios from about 1961 to 1968. These transistors develop whiskers on the inside of the tin plated steel package and these cause short circuits from the case to the transistor die. Replacement exact or near equivalent transistors in a different package are available at a price.
Some '60s Roberts radios helpfully put these transistors inside modules with soldered down metal covers. These are a pain to repair.

John

It is exactly as you describe, the transistors are in the module, at the bottom of the board.
I’m torn, working ones aren’t much money, and this one is making some interesting noises, so I may continue with my circuit bending.

:thumbup:

Folderol wrote:Depending on the precise layout, you can often 'cure' these by simply cutting the ground pin. I'd do that for a Hacker radio, but never for a Roberts - they ripped off Hacker, Dynatron and a few others with their case designs - at the time it never occurred to those companies that their appearance would be copied :(

I can get it to stop oscillating by grounding one of the pins on the transistor board, but the reception is pretty bad.
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Re: Roberts Radio drone synth.

Postby Kwackman » Tue Mar 02, 2021 6:24 pm

The Late Stephen Howell (Hollow Sun) made some interesting virtual instruments/samples.
e.g. "Interference" for Kontakt.
http://www.hollowsun.com/HS2/sli/interference/index.htm
Very cheap too.
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Re: Roberts Radio drone synth.

Postby Arpangel » Wed Mar 03, 2021 9:53 am

Kwackman wrote:The Late Stephen Howell (Hollow Sun) made some interesting virtual instruments/samples.
e.g. "Interference" for Kontakt.
http://www.hollowsun.com/HS2/sli/interference/index.htm
Very cheap too.

Ah yes, I’ve got his VCS3.
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Re: Roberts Radio drone synth.

Postby Martin Walker » Wed Mar 03, 2021 8:23 pm

I was always very impressed with Steve Howell's sample-based libraries, and still use them today (his Mellotron and Novatron are go-tos for instance).


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