Re: Power rating on LF/HF units. Rv!

On Tue, 31 Jan 2006 21:04:08 GMT, szekeres@xxxxxxxx (GregS) wrote:

>In article <MeCdndt7mNm3UULeRVn-gg@xxxxxxxxxxx>, "Arny Krueger" <arnyk@xxxxxxxxxx> wrote:
>>
>>"Don Pearce" <donald@xxxxxxxxxxxxx> wrote in message
>>news:43e2c6c8.45099703@xxxxxxxxxxxxxxxxxxxxxxx
>>> On Tue, 31 Jan 2006 21:21:31 +0100, Peter Larsen
>>> <SPAMSHIELD_plarsen@xxxxxxxxxxxx> wrote:
>>>
>>>>Don Pearce wrote:
>>>>
>>>>> I've recently looked at a dozen or so modern music files in Audition,
>>>>> applying low and highpass scientific filters (3rd order Butterworth)
>>>>> at 2kHz, to see what power would go to a woofer and tweeter
>>>>> respectively.
>>>>
>>>>> Interestingly, the peak level is identical for both - meaning that the
>>>>> woofer and tweeter amps would need the same power rating (they
>>>>> actually produce volts - the power is merely a consequence). Average
>>>>> power levels, though are a different matter, being about 6dB greater
>>>>> for the woofer and the tweeter. That would mean that a 50W tweeter
>>>>> would merit a 200W woofer for a balanced system.
>>>>
>>>>You omit the sensitivity differenc from the calculation, mostly some 6
>>>>to 10 dB in case of a bass reflex lower range unit and a compression
>>>>horn upper unit.
>>>>
>>> Sensitivity difference, particularly those horrible horns, is
>>> something I neglected. The rest still stands, of course.
>>
>>It turns out that the sensitivity difference comes from the compression
>>drivers, not the horns. The horns just make the compression drivers work
>>better at lower frequencies. There are such things as horns that sound quite
>>good.
>
It is all linked. The horn means that for a given SPL, the diaphragm
doesn't have to move as far (because of the better acoustic matching).
That means that Xmax doesn't need to be as big, which in turn means
that the voice coil can be concentrated better into the magnetic field
- hence the improved sensitivity.

>I never made sense out of the term compression driver.
>
>All drivers do create compression.
>and that other way.
>

True enough, but within the horn itself the sound is sort of
compressed (and decompressed) rather than simply radiated. A bit
tenuous, I know - but the best I can come up with.

d

Pearce Consulting
http://www.pearce.uk.com
.

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