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Bridge Class D stereo amp to mono?

#21
agedhorse said:
In general, another urban myth perpetuated by those who have no idea what they are talking about.

With a properly designed class D amplifier, there is absolutely no problem with operating unloaded.

I'm sure there are horribly designed class D products out there, I am not familiar with them however
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Being just a dumb user I have to err on the side of caution even at the level of myth :)
 
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#24
agedhorse said:
I would not recommend doing this at all. You have no idea what the internal topology of the output stages are. Under some conditions it could destroy the amp, under other conditions there will be zero increase in voltage swing or power. You can not possibly know which case you are dealing with until it's too late.
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Checking with the manufacturer first is always a good idea.

It is my understanding that it is based on this device.

Invalid Link Removed
 
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#25
beans-on-toast said:
Checking with the manufacturer first is always a good idea.

It is my understanding that it is based on this device.

Invalid Link Removed
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Different topology. Note that the minus terminal is referenced to ground and is biased at 1/2-Vcc
 
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#26
Back when the world was young, it was a thing to connect a third speaker across the plus terminals of your stereo. You would get whatever instruments were recorded out of phase between the channels. I actually bought a single used AR-2 for this purpose, and later rigged some car stereos this way, where there was a mono speaker in the dash and the fancy stuff was in the back. It was hit or miss what you would get from song to song, but sometimes it was a pretty good effect. Sorry for the digression.
 
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#31
seamonkey said:
One could get a dual voice coil speaker
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Same idea as the combining transformer.

Generally a poor way to do this, and some amps can have stability problems. Only works at VERY low power when it works at all.
 
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#32
agedhorse said:
Same idea as the combining transformer.

Generally a poor way to do this, and some amps can have stability problems. Only works at VERY low power when it works at all.
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The drivers are not available to the average person but it is done successfully.
I have it in some powered PA FRFR cabs now, and it's been around for years, although DSP makes it better these days.
 
#33
Yes, it can work ok but unless it's the dual gap motor type (like the JBL's), often the gap tightness (and sensitivity) suffers... PLUS if there is a failure that causes an insulation breakdown in the voice coil, it's much more likely for the amp to fail when the VC's are not physically separated.

Another serious problem is that the TS parameters vary with the signal difference. If only one channel is driven, that channel sees the moving mass of both channels.

The dual VC concept is most often used successfully when each coil is driven with an identical signal.
 
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#36
Dual voice coil speakers are used in some studio systems. The theory is, it brings the speaker closer to being a point source for monitoring. I find that this can be better acheived in other ways. Dual voice coil speakers seem to fail far too often and having them serviced is expensive.

Real estate is another consideration in using a dual voice coil speaker, probably why it was adopted for car audio.
 
#37
Car stereo dual VC subs I've seen are not very good. Mono out sub amp works a lot better. I don't remember how I wired it, but I did get one to work well enough for its owner by adding a proper amp costing twice as much as the sub. Ok to augment a factory stereo maybe. I band passed it pretty high for a sub.
 
#38
beans-on-toast said:
Dual voice coil speakers are used in some studio systems. The theory is, it brings the speaker closer to being a point source for monitoring. I find that this can be better acheived in other ways. Dual voice coil speakers seem to fail far too often and having them serviced is expensive.

Real estate is another consideration in using a dual voice coil speaker, probably why it was adopted for car audio.
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There might be some very good dual VC subs out there for cars. None that I've seen. Two smaller subs seems to work better if the owner insists on have two channels... in their trunk. I quit helping people because they mostly want cheap junk.

I always wondered what happens when someone wires their stereo amp to a dual VC and gets them out of phase :D
 
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#39
BadExample said:
There might be some very good dual VC subs out there for cars. None that I've seen. Two smaller subs seems to work better if the owner insists on have two channels... in their trunk. I quit helping people because they mostly want cheap junk.

I always wondered what happens when someone wires their stereo amp to a dual VC and gets them out of phase :D
Click to expand...

Probably nothing :)
 

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