Archive for January, 2006

Micro-Sat 500 repair

Saturday, January 7th, 2006

Last year a friend of mine called me for assistance with his “new” speaker set that he had just acquired second-hand from an unknown guy. In fact, the friend had placed an ad to sell his portable keyboard and then somebody called him and offered a speaker set & powered mixer in exchange that the guy would even bring in for a smooth transaction. They did the deal. A few days later the friend was taken aback by the, um, strange sounding satellite speakers and I agreed – we heard sizzling highs on the left and sizzling highs on the right but no mids anywhere, mids totally absent.

The Solton Micro-Sat 500 set consists of two passive SP104 satellites (100W RMS/200W Peak, 4Ohms) and a passive SP515D subwoofer (500W RMS/800W Peak, 2x4Ohms) with integrated crossover and it sold for 2350,- Deutschmarks (approx. 1150,- Euro) list price in the late 1990s. Solton recommended their 10 channel powered mixer ACS10/500 to be bundled with the Micro-Sat 500, and this is what my friend got instead of cash.

After removing the grills I saw two shiny 8″ mid-range chassis and a ¾” tweeter per satellite. Would you think that one of these 8 inchers was dead? Maybe. Would you imagine that all four were dead? Not really. The tweeter is labeled Craaft F1 and reminds me of a popular Foster-Culver / Fostex driver that I think to have seen before on Dynacord, Hughes & Kettner, LEM and other speakers. This is a good one, probably the most expensive part of the SP104.

Using wood screws instead of drive-in-nuts for grills and speakers is not a good decision. And what about the prototype-style crossover with parts glued on a wood plate instead of PCB mounting? Would be a real fun to repair this thing. And, by the way, the 8 inchers look like bottom-of-the-line steel chassis (“organ speakers”), yet adequate but with a slight cheapo appeal.

At the beginning I wouldn’t have believed that all four mid-range chassis are dead, but in fact they were. So I took out the cutter and became a speaker investigator. Three chassis had a broken coil wire right at that point where the wire is guided out from coil to cone and where coil and cone and suspension are glued together. Usually, at this critical joint, the wire is coated with laquer or glue to prevent it from mechanical stress due to vibrations. It seems that this protection has failed in the course of time and then the wire got thinner and thinner until it burned out. My assumption would be that this is a defect of fabrication.

The fourth chassis obviously has been grilled by overload; think of a musician on stage who tries to get audible mid-range sound from the only one left of once four mid-range speakers.

When I contacted Solton they quickly responded with the address of a service technician who sent me four genuine replacement chassis for about 120,- Euro including VAT and shipping, which is a very fair price in my opinion. The replacement chassis had labels on their back revealing that these are TVM (Tesla) ARO 6608 speakers from Czech Republic. Using Google Cache I found out that they once retailed at 229,- Kc per piece (approx. 8,- Euro as to date of this article).