My silly question (BD-Design)

by anubisgrau, Tuesday, May 18, 2010, 18:16 (2806 days ago)

Moved up from topic: REF2010 options and pricing...

Bert
Do you think that the REF2010 can be used extended to 800-900hz crossover range?
I'm playing with a relatively affordable summer project of a 2-way box for small rooms. In a few words, it's a 15" conical horn with a 15" driver, same directivity around crossing frequency which should be tuned around 800-900hz as it's a limit from the horn of that size. BD15 is probably the most linear bass driver I know when it comes to higher frequencies and looks like a perfect solution.
So the question is: how high can BD15 play in the REF2010 and still being linear?
Thanks!

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My silly question

by Bert @, Tuesday, May 18, 2010, 19:58 (2806 days ago) @ anubisgrau

Hi Gordan,

Do you think that the REF2010 can be used extended to 800-900hz crossover range?

An enclosure is only to prevent cancellation between the front and the rear of the driver (to be able to play deep bass as efficient as possible). Higher frequencies are being reproduced by the driver only and if it is capable to do that properly then yes...

So the question is: how high can BD15 play in the REF2010 and still being linear?

For quality output without too much compromising then 900Hz would be the limit for me, going higher will only result in loss of detail and transparancy.

Bert

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BD-Design - Only the Best!

My silly question

by anubisgrau, Wednesday, May 19, 2010, 01:26 (2806 days ago) @ Bert
edited by anubisgrau, Wednesday, May 19, 2010, 01:37

thanks bert

last questions:

1. would an extention of BD15 in such a box towards 900hz (perfect for me!) mean a comprimise in the lowest region and earlier roll off - would you be able to predict what would be a -3db and -6db points?

2.do you have any measurements of the polar response of BD15 vs frequency. i would need to know approximately how it behaves around 900hz regarding directivity. i would need this to be around 90 degrees...

3.also, do you have anywhere a measured data for BD15 inductance? i assume it must be very low considering you find a 30w amp optimal, however i'm curious to know how much it is as i'd love to try it even with lesser watts and this is quite an important data for me as i'm currently weighing it against AE TD15M in apollo version which is the lowest unductance driver with a low mms i know...

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My silly question

by Bert @, Wednesday, May 19, 2010, 08:19 (2806 days ago) @ anubisgrau

1. would an extention of BD15 in such a box towards 900hz (perfect for me!) mean a comprimise in the lowest region and earlier roll off - would you be able to predict what would be a -3db and -6db points?

The box does not do anything to the higher frequencies or the other way around. It's nature that makes loudspeakers become more directive with increasing frequencies. Even tweeters start to beam in their highest frequencies from the moment the wavelength is smaller than the diameter of the moving diaphragm (and a dome does NOT make that better).

2.do you have any measurements of the polar response of BD15 vs frequency. i would need to know approximately how it behaves around 900hz regarding directivity. i would need this to be around 90 degrees...

No I don't have that but if you can find one from another 15" driver then it will not be much different.

3.also, do you have anywhere a measured data for BD15 inductance? i assume it must be very low considering you find a 30w amp optimal, however i'm curious to know how much it is as i'd love to try it even with lesser watts and this is quite an important data for me as i'm currently weighing it against AE TD15M in apollo version which is the lowest unductance driver with a low mms i know...

These figures can be found on the BD15 page but here they are anyhow (not too bad for a 16 ohm driver having more windings in general) but not that much interesting to know for bass frequencies as far as I can tell either?

L @ 1kHz - 1.3839
L @ 10kHz - 0.7576

BTW, what has inductance to do with the power needed for the bass driver? :confused:

BTW2, 30 Watt is sufficient for the BD15's and in small room conditions and not playing too loud then 5Watts will do also. If you have a very big room and want to listen very loud then better use 150Watts or more.

I never mentioned that 30W is optimal....why should 30W be optimal anyhow?

Bert

PS, do not theorize too much, in real life things are never optimal. If you want the same directivity as the horns you are going to use then give the bass driver a wave guide so that it will match more perfectly.

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BD-Design - Only the Best!

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