questions about Beta24 and Beta22 as speaker amp
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AudioCats

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some simple questions, hope you guys don't mind answering (the beta22 thread is too big by now).
 
* For speaker use, if all I ever need is 35W into 8 ohm, will there be much advantage to build a Beta24 vs. a 4-board Beta22?
* Which (gain) version of Beta22 kits are needed for speaker use? 
 
 
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amb

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Quote:
Originally Posted by AudioCats /img/forum/go_quote.gif
* For speaker use, if all I ever need is 35W into 8 ohm, will there be much advantage to build a Beta24 vs. a 4-board Beta22?
 
β22 was designed primarily to be a headphone amp.  Although it is capable of driving speakers, the MOSFETs and their stock heatsinks are adequate only for light duty speaker use.  Even with large offboard heatsinks there will eventually be a thermal resistance bottleneck for any sustained use at high-ish volumes.  This depends on the efficiency of your speakers and the room size and acoustics, of course.  β24, on the other hand, was designed specifically to be a high powered speaker amp.  The fully-differential topology of the β24 also makes it much easier to support balanced and unbalanced preamps.  β24 might be more power than you need, and it's a more challenging project, so you need to weigh the pros/cons.
 
Quote:
* Which (gain) version of Beta22 kits are needed for speaker use?
 
Depends on source and efficiency of the speakers, but typically speaker power amps have a gain of anywhere from 15-25.
 
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AudioCats

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Thanks AMB, you da man :)
 
I saw the Beta24 boards are available, how much (ball park figure) parts cost am I looking at for completing a set of amp boards? (just amp boards, not counting hardware, connectors, transformer and power supply system).  
 
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amb

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PM me your email address and I'll send you the β24 PDF documentation, including the full BOM.  You could then do your homework and figure it out.
 
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Iniamyen

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In my case the "other stuff" beyond the main amp boards was probably 300% of the cost of the amp boards. I can't be sure since I purposefully have not been keeping track
.
 
So yeah, the cost of stuffing the amp boards is not a good metric for project cost. It will be expensive but well worth it.
 
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xxbaker

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Not directly related, but if you're running the amp from unbalanced input, do you lose half the wattage the amp is capable of?
 
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amb

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Not directly related, but if you're running the amp from unbalanced input, do you lose half the wattage the amp is capable of?


No, it will still output full power.
 
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Yup, especially in the case of the beta24 the cost of the boards + parts is not a very good gauge of the overall project cost. It was so intimidating I decided to buy someone else's instead :wink:
 
Quote:
In my case the "other stuff" beyond the main amp boards was probably 300% of the cost of the amp boards. I can't be sure since I purposefully have not been keeping track
.
 
So yeah, the cost of stuffing the amp boards is not a good metric for project cost. It will be expensive but well worth it.


 
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digger945

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xxbaker, to quote amb in the Beta24 thread on Headwise...
"The power is very real." , taken from this post.
 
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