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Old 22nd June 2008, 08:37 PM   #481
fred76 is offline fred76  Philippines
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Default 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.
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Old 22nd June 2008, 09:01 PM   #482
gedlee is offline gedlee  United States
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Quote:
Originally posted by jcx


then why the discussion of thermal compression and shorting rings?
I've already solved those problems.
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Old 22nd June 2008, 09:02 PM   #483
gedlee is offline gedlee  United States
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Quote:
Originally posted by chrismercurio
I know it sounds crazy but maybe, if we just let Earl bring to market the kits he wants to bring to market as he is the expert on what he wants out of a loudspeaker, the results will be what they are supposed to be.

Best to all,

Chris

Thanks Chris, I can agree with this.
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Old 22nd June 2008, 09:09 PM   #484
gedlee is offline gedlee  United States
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Default Re: DE250 16 Ohm

Quote:
Originally posted by fred76
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.

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.
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Old 22nd June 2008, 09:15 PM   #485
gedlee is offline gedlee  United States
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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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Old 22nd June 2008, 10:02 PM   #486
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Quote:
Originally posted by gedlee
I've looked at their Neo woofers in the past. If weight is not an issue then the extra price did not seem justified to me. The 15NW76 does look very attractive, except that its efficiency may be too high to mate with the DE250.
I'll be using the DE250 with your 10" waveguide, what is the sensitivity after it's EQ'ed flat?
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Old 22nd June 2008, 10:57 PM   #487
tinitus is offline tinitus  Europe
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15NW76 does indeed look interesting, a bit high Fs and maybe a bit low Qts fore closed
How can a 100db woofer have too high sensitivity fore a 108db CD ?

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Old 22nd June 2008, 10:57 PM   #488
gedlee is offline gedlee  United States
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Quote:
Originally posted by augerpro


I'll be using the DE250 with your 10" waveguide, what is the sensitivity after it's EQ'ed flat?

It should be about 98 dB. That of course depends on the crossover.
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Old 23rd June 2008, 12:38 AM   #489
Sheldon is offline Sheldon  United States
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Quote:
Originally posted by Patrick Bateman
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.
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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Old 23rd June 2008, 04:48 AM   #490
fred76 is offline fred76  Philippines
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Default Re: Re: DE250 16 Ohm

Quote:
Originally posted by gedlee



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.

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/i...?topic=24627.0
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