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Thermal limiter: why not based on RMS current?

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Doug Fowler:

--- Quote from: Scott Holtzman on January 07, 2021, 02:59:52 AM ---
John do you know how the Meyer processors worked that had an input to the speaker?  I know it did more than limit it changed the crossover frequency too IIRC.

--- End quote ---

I was told by a "guy" in a position to know it's actually Apogee controllers that used the sliding xover, not Meyer. I used to have UPAs and USWs pre-measurement days.

I would love to see this settled. Anyone with a biamp Meyer analog controller could easily verify this with a simple measurement.

Helge A Bentsen:

--- Quote from: Doug Fowler on January 07, 2021, 03:52:53 AM ---I was told by a "guy" in a position to know it's actually Apogee controllers that used the sliding xover, not Meyer. I used to have UPAs and USWs pre-measurement days.

I would love to see this settled. Anyone with a biamp Meyer analog controller could easily verify this with a simple measurement.

--- End quote ---

According to a measurement friend, Meyer didnít use sliding xovers, but once the controller started limiting in one band, the audible effect was similar to sliding crossovers. When measured with one band in limit, one of the bands would stay at itís level while the other would increase level leading to the audible xover moving. The electronic crossover stayed put.

John Roberts {JR}:

--- Quote from: Scott Holtzman on January 07, 2021, 02:59:52 AM ---
John do you know how the Meyer processors worked that had an input to the speaker?  I know it did more than limit it changed the crossover frequency too IIRC.

--- End quote ---
I don't have any specific knowledge about that but vaguely recall some pre-DSP speaker processors that used a sliding HPF to reduce LF bass energy at high output levels.

I also suspect some audiophools played with 4 wire Kelvin sensing (2 speaker wires and 2 sense wires) to provide numerically high damping factor.

I momentarily considered an after market SKU that performed the the current sensing between amp and loudspeaker to provide the data to impute voice coil temperature, but almost as quickly abandoned it after thinking about the nightmare of customer service for users that in fact need such a product, and speaker specific set-up assistance. 

By now, decades later this should be mature technology and premium brands should be pretty well managed. Smart power amps with inboard current sensing, and modest DSP "can" do this but must be programmed for specific loudspeakers. 

Caveat, I have been out of the trenches for a couple decades so not up on latest technology.

JR

Lee Douglas:

--- Quote from: John Roberts {JR} on January 07, 2021, 09:42:33 AM ---
I also suspect some audiophools played with 4 wire Kelvin sensing (2 speaker wires and 2 sense wires) to provide numerically high damping factor.


--- End quote ---

I had a Peavey product called Dynamic System Controller that did that.  I used it on a 3020ht/415SUB system.  Output to amplifiers and low/mid/high sense wires from the speaker output of each amplifier.  Or was that something different?

Jim McKeveny:

--- Quote from: Doug Fowler on January 07, 2021, 03:52:53 AM --- Apogee controllers ... used the sliding xover, not Meyer. 

--- End quote ---

Renkus-Heinz had "Smart" loudspeaker line that moved crossover points upward for driver protection. Boxes were 2-15's handing off to a 2 inch HF. The whole crossover region polars adjusted dynamically with material. I gigged outdoors in San Jose on one of these rigs, way undersized for the crowd. The sonic effect was, umm, novel.

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