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DIY Waveguide loudspeaker kit

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fred76

Member
Joined 2005
DE250 16 Ohm

Hi Earl,

Your kit webpage says that you use the DE250-16, which is the 16 ohm version of this driver(?). Is it a deliberate design choice to use 16 ohm versions? If so, for what reason/s? So if one is to source their own drivers (which I surmise are mostly 8 Ohms in the retail market), would a different set of crossover values be used?

Thank you.
 
gedlee

gedlee

Member
Joined 2004
gedlee.com
Re: DE250 16 Ohm

fred76 said:
Hi Earl,

Your kit webpage says that you use the DE250-16, which is the 16 ohm version of this driver(?). Is it a deliberate design choice to use 16 ohm versions? If so, for what reason/s? So if one is to source their own drivers (which I surmise are mostly 8 Ohms in the retail market), would a different set of crossover values be used?

Thank you.
Click to expand...


Yes of course its deliberate. The reason is that the voltage efficiency of the 8 ohm is too high so the higher Re helps. If you don't use exactly the same driver that the crossover was designed for it won't work properly. This is always the case.
 
gedlee

gedlee

Member
Joined 2004
gedlee.com
We used the Eminence 12 HO with the shorting ring in the ESP12 because we thought (based on some early tests and published specs) it did not have a small dimple in the woofers passband that the 12TBX100 had. But when we got the bulk shipment they all had the same problem as the 12TBX100. If the prices are comparable then I would opt for the B&C, but as I recall the price that I get on the Eminence was quite a bit lower than the B&C and since it worked about the same the Eminence was attractive. But this reduction is not $100, more like $50.
 
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Sheldon

Member
Joined 2003
Patrick Bateman said:
The "real" Summa is a no-compromise design that mates a 15" waveguide & a 15" woofer. The achilles heel of the Summa is the woofer. There are only a handful of 15" woofers which can play into the midrange. The B&C 15TBX100 fits the bill, but it is E-X-P-E-N-S-I-V-E.
Click to expand...

I know that others have mentioned the 15" Lambda designs, now sold by AE. I can tell you from personal experience that mine play and measure very well. I have the Lambda Apollo motor TDX, and they are expensive too. But I would guess that the main difference between the Apollo and the single shorting ring would be at very high SPL levels, so the Apollo is likely overkill here.

Sheldon
 
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fred76

Member
Joined 2005
Re: Re: DE250 16 Ohm

gedlee said:



Yes of course its deliberate. The reason is that the voltage efficiency of the 8 ohm is too high so the higher Re helps. If you don't use exactly the same driver that the crossover was designed for it won't work properly. This is always the case.
Click to expand...


Thank you Earl... So if used with an 8 ohm woofer, the woofer gets most of the power.

Some Summa pics from an old thread I found online: http://www.audiocircle.com/circles/index.php?topic=24627.0
 
gedlee

gedlee

Member
Joined 2004
gedlee.com
Re: DE250

Grumpy_Git said:
The DE250 is listed on the B&C website as an 8 Ohm driver, is the 16 Ohm version you use a special order item?

Nick.
Click to expand...


No they stock them here in the US. It may be different in other parts of the world however. Its just a diaphragm change. 8 or 16 is pretty much arbitrary, but the 16 ohm keeps the pad resistors smaller. I used 8 for years and then switched to 16. It makes the other components in the crossover smaller and less expensive.
 
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