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Renovating VideoLogic Sirocco Stereo Speaker System

I have had a VideoLogic Sirocco speaker system for about 15 years now, originally manufactured in 1999 my dad bought it to use at a kid’s club he helped run. A couple of years later he was no longer involved and the speakers were not being used – stored in the shed for a while they became a little damaged by the elements with some rust showing on the amplifier cabinet. He then gave them to me as a replacement for an awful set of speakers that I had which had been damaged (i don’t remember how). Since then I’ve hung on to these speakers because they seem to me to be pretty good quality and I love the tone and clarity of the sound that they produce.

damaged cone

Sadly time has taken its toll on these speakers and the original Audax mid range speaker cones which were made of foam and cardboard have now disintegrated. Additionally, the original volume and adjustment potentiometers are noisy (and I have tried cleaning them) and the headphone jack socket which uses a spring to complete the circuit when there are no headphones attached doesn’t reliably maintain the circuit.

Therefore I have decided to renovate these speakers, more because they have a kind of sentimental value to me than because they’re worth the time. After all, I have a couple of sets of Tannoy HiFi bookshelf speakers which I could happily use instead and decent amplifiers are not hard to find. I started this renovation project when I moved into my last house around the beginning of 2015 because I thought before I took the time to wire them in I should get them back into a working state. I ordered the replacement cones around this time but the project stalled after that and personal issues got in the way. I have now moved again and am getting settled, and in going through my stuff found these speakers and the replacement cones. They are vastly superior to the speakers currently attached to my computer so I am going to get this project finished up so I can use them.

To rectify the headphone socket I am just going to remove it and bridge the circuit as if it was there without headphones inserted. This is because I never use it for headphones because I have a separate headphone amplifier for them. I haven’t yet decided whether to place something in the vacant hole left by the headphone jack or to simply leave it.

The potentiometers I am attempting to find like for like replacements.
The volume potentiometer is a stereo A203 (20k Ohm logarithmic) with no detents, a smooth 6mm diameter shaft, 5mm spacing between pins and a shaft length of 13mm.
The sub potentiometer is a mono A103 (10k Ohm logarithmic) with a centre detent and also has the same dimensions as the volume potentiometer.
The attitude potentiometer is a stereo B104 (100k Ohm linear) with centre detent and again the same dimensions as the volume potentiometer.

the pots

While I am resoldering these potentiometers I also want to replace the bright blue power indicator led with a much less bright red led. This is because when watching a video or something in the dark, the blue led is bright enough to be distracting.

To replace the disintegrated cones I attempted to track down the exact same models from Audax but found that they haven’t been in production since around the time that the system was manufactured. So as an alternative I found some Monocor “One” speakers which, from what little I understand about speaker cones, have similar frequency responses and power ratings to the original Audax cones. I also believed that they were of the same size as the ones I was replacing, however, having ordered these replacements and laid them up next to the originals, while the cones themselves are the same size, the replacement enclosure requires an additional 6mm clearance in the cabinet. I have therefore removed the extra material with a rasp and a file. Finally, the spade connectors of the original speaker cones were a different size to the new ones, so I cut off the connectors and soldered the cables directly to the cones.

Speaker cabinet with new cone fitted

I will complete this project soon. I have modified both cabinets and changed both cones over, I have desoldered the existing pots and am just waiting for new pots to resolder and then reassemble the amplifier and the project will be completed.