CLS ii - bias supply connection

Hi,

I'm new here and have just bought a pair of circa 1992 CLSii -really just to learn about them. Btw I'm an electronics engineer.

ML were kind enough to send me audio circuits for the ii, iia, iiz. I thought I might upgrade the iis to iiz circuit - seems easy enough. The circuits are very unclear on where the bias supply connects though. I guess usually the bias would go between the ground point and the film. afaik the usual electrostatic panel arrangement is a balanced audio drive about a ground referenced bias of a few kV. But the CLS audio circuits don't look obviously balanced. Oh well - here's where the learning starts. If someone can tell me where the bias connects I'd be very interested (also correct voltage). The CLSiiz is the most weird - it shows one side of the panel being earthed? Connecting the bias between one panel and the film makes no sense at all. Sorry I'm sure I'm not using the correct terms here but you'll know what I mean

I guess I can figure it out with a multimeter / hv probe easily enough - don't worry I won't zap myself.

Any help appreciated though.

BTW - these ones seem to be well looked after but have been out of action for a while - how long should it take them to come on-song? They have picked up in both volume (efficiency) and sound quality quite a bit over a couple of hours tonight.

tks

Murray

Welcome.
It's not very likely that ML would have changed panel connections between these models but more probably just passive crossover section is the differences are. You would need to be sure of things before making any modifications.

panels changed between the CLS and CLS II series. i do not beleive that the panels changed between the various II series, so the connections to the panels are equally likely to be the same across the II series.

Check the tweaks section for possible assistance.

Welcome Murray. Here is the link to a thread here at MLC about the differences in electronics on CLSII's.


http://www.martinloganowners.com/forum/showthread.php?t=10823

Thanks

Thanks to all for the tips. If anyone reads this and can explain more about where the bias / energisation connects to the crossover (it isn't shown in the circuits) I'd be interested, otherwise I'll post in Tweaks as suggested.

Best

Murray

murrayp said:

Thanks to all for the tips. If anyone reads this and can explain more about where the bias / energisation connects to the crossover (it isn't shown in the circuits) I'd be interested, otherwise I'll post in Tweaks as suggested.

Best

Murray

Click to expand...

Hola Murray... as I understand there is no crossover at the CLSs, what you have is a tone shape. The input signal goes to this tone shape circuit, and then goes to the transformers. The transformers modulate the stat panels. The DC bias voltage (Red) goes to the diaphragm, the blue (front stat) and black (back stat) From the multiplier voltage, you get about 3 to 4KV. Happy listening,
Roberto.