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Power attenuator, not simple dummy load


 
8/8/2000 9:40 PM
Kremator
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Power attenuator, not simple dummy load
Hi,  
I'd like to build something like marshall powerbrake, not a line out, but something to power speakers with. I've read several documents about dummy loads and i still don't know, where and what should i tap to power speakers, not the mixer.  
Thanks in advance,  
K.  
PS: THD hotplate complete schematics with all parts' values is my dream
 
8/9/2000 2:37 AM
Ryan
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PS: THD hotplate complete schematics with all parts' values is my dream  
 
You and me both!
 
 
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8/9/2000 3:23 AM
Chris Hogan
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Hell yeah, me too!  
 
I had one for a bit...back when I knew less than nothing (as opposed to now when I just know nothing!) Wish I'd copied down the circuit...
 
8/9/2000 8:25 AM
anonymous
I have the drawings of Marshall PowerBrake  
look at http://hem.passagen.se/lako63/ritninga.htm  
 
lars
 
8/9/2000 9:44 PM
Kremator
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Yeah,  
i know that. But the problem is with the tapped inductor. Need some more info. Anybody ever tried to make a thing like this?  
K.
 
8/9/2000 11:09 PM
Kremator
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Hi,  
I did some research about power attenuators. Some of them use multitapped transformer somehow. How does this work? I can lower the voltage by a transformer, but how about the current?  
 
Another thing. What are typical inductances of 4,8,16ohm speakers? I think powerbrakes's tapped inductor should be the 16 ohm value, as there's some tap switching for the 8 ohm. But how does a speaker attached to a tap affect the whole inductance? If i put two inductors in parallel, it's like paralleling resistors. L=(La*Lb)/(La+Lb). The question is, is the powerbrake designed to accept this, or it just doesn't matter so much.  
 
On Mr.Aiken's pages i found several usable dummy loads. Would it be possible, just to tap the "working" inductor, like the one in powerbrake (or simmilar way) to get the result i want?  
K.
 
8/10/2000 12:30 AM
SteveG
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I have a couple of speakers lying around, and I've been wondering about building them into a small sealed box and using them as a power attenuator. I can't see why the box would need to be any bigger than the minimum size to allow them to fit. they could be positioned facing each other to reduce the size. Has anyone tried anything like this? Good or bad results?  
 
Steve
 
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