# Hacking a floor stander



## fredm (Aug 28, 2008)

I have a single Infinity Beta 50 speaker that I never used, because I was a moron and bought one thinking I could find another one later. 

Now, years later, I also have some spare Beta 20 speakers (replaced) and was thinking of using those tweeters/crossovers and make some custom bookshelf speaker enclosures with an 8" driver each from the Beta 50, using half the box volume and longer port. 

I realize this is a crack pot plan. I am pretty tired and delirious now though so it seems like a good idea. 

Do you guys think this has a chance to end up sounding better? I realize they will be huge "bookshelfs" but still easier to deal with than a single useless Beta 50. 

Thanks


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## fusseli (May 1, 2007)

Sure it's doable. You just need to measure the T/S parameters of the driver, then you'll be able to design the optimal box and alignment for it.

Are you planning on a new crossover also?


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## fredm (Aug 28, 2008)

I would like to use the Beta 20 crossover. 2.4kHz; 24 dB/Octave. The Beta 50 is a 3-way crossover and I only have one so I won't be using it. 600 Hz, 3.3kHz; 24 dB/Octave 
If they sound horrible I will change them to see if the crossover is the problem. This just has too much fail potential to put much cash down ahead of time. 

The Beta 50 is tuned to 37Hz according to this article. Would there be any way to aproximate a similarly tuned enclosure with 1 driver instead of 2? I know it a will be a smaller enclosure, with a larger vent obviously. I have no idea where to get the Thiele/Small for these.


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## DrDyna (Jul 21, 2011)

fredm said:


> I would like to use the Beta 20 crossover. 2.4kHz; 24 dB/Octave. The Beta 50 is a 3-way crossover and I only have one so I won't be using it. 600 Hz, 3.3kHz; 24 dB/Octave
> If they sound horrible I will change them to see if the crossover is the problem. This just has too much fail potential to put much cash down ahead of time.
> 
> The Beta 50 is tuned to 37Hz according to this article. Would there be any way to aproximate a similarly tuned enclosure with 1 driver instead of 2? I know it a will be a smaller enclosure, with a larger vent obviously. I have no idea where to get the Thiele/Small for these.


The problem with the crossover is it's designed to work with a particular driver in a particular enclosure. It's more than a 2.4 khz crossover, it probably has baffle step compensation calculated, which changes depending on the width of the enclosure. Also, the drivers having different impedance and inductance profiles, plus any frequency correction that's been applied, such as the woofer in the beta 20 might have a cone breakup that needed to be notch-filtered with the crossover, while the beta 50 woofer's breakup is in a different place.

If the beta 50 and beta 20 both have the same width of cabinet and the same woofer, you could probably do what you're proposing, but if they're different, the resulting speaker could be pretty gnarly.


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## fusseli (May 1, 2007)

Drdyna is absolutely right, you cannot use a crossover meant for one set of drivers in a specific cabinet in a different set of drivers and cabinet. It would function (sound would come out) but it is sure to be less than ideal. I also doubt that you will get any deeper bass performance with a smaller cabinet tuned lower. As it is, 37 Hz isn't too bad, but it's not that low either.


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