Question on active speaker possible patent

jman11964 · 10th February 2011, 01:03 PM

Hi - asking here because I'm hoping someone will have a better memory (or Google-foo) than I do.

I'm interested in a technique for building a 3-way active system with two amp channels where on channel drives the mid and the other drives the bass and tweeter.

I had in mind (and this may be from an old SpeakerBuilder article, but I don't have the old magazines any more) that this was patented.

Has anyone tried this - specifically with an analogue series crossover to protect the tweeter and divide the A and C signals?

Any links to prior art on this (including any such patent etc) would be great. I goofed when I wired my home - just put two lots of coax in to the speaker locations and didn't run a cat5 at the same time.

Thanks
James

phase_accurate · 10th February 2011, 02:48 PM

espacenet — Original document

jman11964 · 10th February 2011, 03:07 PM

Many thanks!

Charles Darwin · 10th February 2011, 03:30 PM

Sorry for my ignorance but glancing at the patent it appears to successfully combine all the disadvantages of passive xovers with all the disadvantages of active ones.
What am I missing?

jman11964 · 10th February 2011, 03:45 PM

Well, if you only have (or want to use) two channels of active amplification, its handy. And the high and low pass filters in the split aren't there to perform the normal crossover function - they are there to prevent crosstalk between the two ranges, so the passive low pass for the woofer can be well above its cross to the midrange, and the high pass for the tweeter can be well below its cross to the midrange.

Stopping the high freq get to the woofer stops it exciting cone breakup modes (though, I suspect with the relative sensitivities of the drivers I'm expecting to use its not such a big deal) - but I definitely want to prevent the bass signal hammering my (ribbon) tweeter. At least, that's my understanding.

CharlieLaub · 10th February 2011, 04:21 PM

I don't really see the point in "saving" one channel of amplification. If you already have two channels of amplification present, you already have a power supply for that. Increasing the PS capacity by 50% and adding on another amplifier probably costs less money than creating the passive filters after the W+T amp as shown in the patent. WHen this was written, amplification was likely much more expensive than today. Now there are many inexpensive options in many amplification classes (e.g. AB, T, D).

Since there is (as shown in the patent) already an active 3-way crossover before the amps, putting passive elements after the amps sort of removes one of the main advantages of active circuitry - the direct connection between amp and driver.

-Charlie

dewardh · 10th February 2011, 04:24 PM

Quote:

Originally Posted by Charles Darwin

Sorry for my ignorance but glancing at the patent it appears to successfully combine all the disadvantages of passive xovers with all the disadvantages of active ones.
What am I missing?

It is using the Patent Office to keep people from doing stupid things. Anyone (with a clue) is going to look at the diagram in the patent and think "I can avoid that simply by dropping the passive stuff and adding a third amp".

And they'll get a better speaker for it . . .

jman11964 · 10th February 2011, 04:33 PM

Sure, but in my case:
- I have a pair of stereo Cyrus power amps that have a form factor reasonable to site under the speakers
- I have 2 off coax from where I'd like to put the controller to each speaker site
- I'm happy to build the 3-way active crossover part in a PC

So it means I can have fun playing with digital crossovers with the kit and wiring I have in place.

So no, I don't think its a stupid thing. Sorry dewardh - sure you want to accuse people of having no clue just like that?

Now, if I could use the coax to put 4off S/PDIFs down the lines then maybe I'd get some cheap DACs and a couple of T-amps to run the tweeters, but running multiple digital consumer signals seems to be bizarrely tricky and I'm not sure I want to pay for an AES16 and level/protocol converters yet.

Right now I'm keen to have fun with digital crossovers and speaker stuff, not building amps and opamp active stuff. Though miniDAC is certainly tempting.

pedroskova · 10th February 2011, 04:34 PM

I don't think I'd want to drive my bass drivers with the a 12W SET amp, nor would I want to drive my ribbon tweeter with a 200W SS PA amp.

horses for courses

Charles Darwin · 10th February 2011, 04:52 PM

If one were restricted to two amps I would always run the bass active and split mids and tops passively.
Would seem the most sensible way to me.

10th February 2011, 01:03 PM	#1
jman11964 diyAudio Member Join Date: Feb 2011	Question on active speaker possible patent Hi - asking here because I'm hoping someone will have a better memory (or Google-foo) than I do. I'm interested in a technique for building a 3-way active system with two amp channels where on channel drives the mid and the other drives the bass and tweeter. I had in mind (and this may be from an old SpeakerBuilder article, but I don't have the old magazines any more) that this was patented. Has anyone tried this - specifically with an analogue series crossover to protect the tweeter and divide the A and C signals? Any links to prior art on this (including any such patent etc) would be great. I goofed when I wired my home - just put two lots of coax in to the speaker locations and didn't run a cat5 at the same time. Thanks James

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10th February 2011, 02:48 PM	#2
phase_accurate diyAudio Member Join Date: May 2002 Location: Switzerland	espacenet — Original document

10th February 2011, 03:07 PM	#3
jman11964 diyAudio Member Join Date: Feb 2011	Many thanks!

10th February 2011, 03:30 PM	#4
Charles Darwin diyAudio Member Join Date: Nov 2009 Location: Birmingham, UK	Sorry for my ignorance but glancing at the patent it appears to successfully combine all the disadvantages of passive xovers with all the disadvantages of active ones. What am I missing?

10th February 2011, 03:45 PM	#5
jman11964 diyAudio Member Join Date: Feb 2011	Well, if you only have (or want to use) two channels of active amplification, its handy. And the high and low pass filters in the split aren't there to perform the normal crossover function - they are there to prevent crosstalk between the two ranges, so the passive low pass for the woofer can be well above its cross to the midrange, and the high pass for the tweeter can be well below its cross to the midrange. Stopping the high freq get to the woofer stops it exciting cone breakup modes (though, I suspect with the relative sensitivities of the drivers I'm expecting to use its not such a big deal) - but I definitely want to prevent the bass signal hammering my (ribbon) tweeter. At least, that's my understanding.

10th February 2011, 04:21 PM	#6
CharlieLaub diyAudio Member Join Date: Mar 2007 Location: California	I don't really see the point in "saving" one channel of amplification. If you already have two channels of amplification present, you already have a power supply for that. Increasing the PS capacity by 50% and adding on another amplifier probably costs less money than creating the passive filters after the W+T amp as shown in the patent. WHen this was written, amplification was likely much more expensive than today. Now there are many inexpensive options in many amplification classes (e.g. AB, T, D). Since there is (as shown in the patent) already an active 3-way crossover before the amps, putting passive elements after the amps sort of removes one of the main advantages of active circuitry - the direct connection between amp and driver. -Charlie

10th February 2011, 04:33 PM	#8
jman11964 diyAudio Member Join Date: Feb 2011	Sure, but in my case: - I have a pair of stereo Cyrus power amps that have a form factor reasonable to site under the speakers - I have 2 off coax from where I'd like to put the controller to each speaker site - I'm happy to build the 3-way active crossover part in a PC So it means I can have fun playing with digital crossovers with the kit and wiring I have in place. So no, I don't think its a stupid thing. Sorry dewardh - sure you want to accuse people of having no clue just like that? Now, if I could use the coax to put 4off S/PDIFs down the lines then maybe I'd get some cheap DACs and a couple of T-amps to run the tweeters, but running multiple digital consumer signals seems to be bizarrely tricky and I'm not sure I want to pay for an AES16 and level/protocol converters yet. Right now I'm keen to have fun with digital crossovers and speaker stuff, not building amps and opamp active stuff. Though miniDAC is certainly tempting.

10th February 2011, 04:34 PM	#9
pedroskova RIP Join Date: Dec 2002 Location: C'ville VA, USA	I don't think I'd want to drive my bass drivers with the a 12W SET amp, nor would I want to drive my ribbon tweeter with a 200W SS PA amp. horses for courses

10th February 2011, 04:52 PM	#10
Charles Darwin diyAudio Member Join Date: Nov 2009 Location: Birmingham, UK	If one were restricted to two amps I would always run the bass active and split mids and tops passively. Would seem the most sensible way to me.

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