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Old 14th October 2008, 10:57 AM   #1
diyAudio Member
Join Date: Mar 2006
Location: Cheshire
Default Bass Exciter driver placement

I am about to start a new project, which is a pair of powered subwoofers.

I have purchased:
2x BX10 Bass Exciters by Ralph Mantel
2x BXP 10 matching passive radiators
2x Plate amps
Purchased from

BX 10
25 cm top class bass driver with coated paper cone, twin magnet, rubber surround, ventilated magnet system and sheet steel basket.
output (continuous/programme): 150/300 Watt
impedance: 4 Ohm
resonance frequency fs: 30 Hz
DC resistance Rdc: 3.5 Ohm
mechanical Q factor : 6.76
electrical Q factor Qes: 0.36
total Q factor Qts: 0.34
equivalent volume of compliance Vas: 50.07 L
voice coil inductance at 1 kHz: 3.12 mH
effective mechanical mass incl. air load Mms: 91.3 g
mechanical compliance Cms: 0.30 mm/N
effective piston radiating area Sd: 365 cm2
electromagnetic force factor BI: 13.11 N/A
sensitivity (2.83V /1m/1kHz): 87 dB
voice coil height: 23.5 mm
voice coil layers: 4
outside diameter: 258 mms
cut-out required: 229 mm
mounting depth: 133 mm
countersunk depth: 11 mm
cone diameter: 169 mm
mounting holes: 8x5 mm on 250 mm diameter circle

BXP 10
The passive radiator BXP10 was developed as an addition to the BX10 driver. The BXP10's excursion is double (a piece of cake for the passive one) compared with the BX10, possesses a rigid MDF cone and is easy to tune by attaching weights on the inside.
outside diameter: 255 mm
cut-out required: 223 mm
mounting depth: 74 mm
countersunk depth: 7 mm
cone weight: 180 g
resonance frequency in 17 litre cabinet: 46 Hz
cone diameter: 169 mm
surround width: 35 mm
effective piston radiating area Sd: 365 cm2
mounting holes: 8x5 mm on 245 mm circle

These will be placed in two small enclosures 30cmx30cmx26cm internal, 36cmx36cmx31cm external with 5cm legs

My aesthetic preference is to have the passive radiator facing forwards, with the main driver facing downwards, or perhaps visa/versa.

Will this work well with these drivers? Perhaps the passive will not be able to be tuned properly with weights if it is facing downwards? Perhaps the main driver will not like facing downwards either?

The other alternative is to have the driver and the passive on opposite sides of the cube.

Opinions please?
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Old 14th October 2008, 12:15 PM   #2
diyAudio Member
Join Date: Mar 2006
Location: Cheshire
I thought that I should mention that initially these are to be used with some Fostex FX120 fullrangers in MLTL cabs.

The crossover on the plate amp can be between 170hz and 40hz.
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Old 14th October 2008, 03:32 PM   #3
sreten is offline sreten  United Kingdom
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Join Date: Nov 2003
Location: Brighton UK

somewhat different parameters ?

and here :

I estimate you will need to ~ double the PR's mass.

I'd say both should be mounted vertical, keep the BX10 magnet
away from any transformers, make sure they do not foul the

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Old 14th October 2008, 04:11 PM   #4
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Join Date: Mar 2006
Location: Cheshire
BK Electronics: 49.30
Lautspreckershop: E119
Hifisound: E169
I think that I paid 60 for a BX10, with a passive radiator, and postage included, so not too bad.

It is nice to see that us Brits are not being ripped off for once.

Sreten: I suspected that these units need to be vertical. Can anyone else confirm this?

Also, if I am going to crossover at higher fequencies (up to 170hz is possible), now, or in the future, the main driver will need to face foward; yes?

What is the minimum distance that should separate a driver from the transformer in the plate amp? I had not considered this (apart from working physically).

See photos: (large transformer)

Click the image to open in full size.

Click the image to open in full size.

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Old 14th October 2008, 11:16 PM   #5
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Join Date: Mar 2006
Location: Cheshire
Vikash has his passive facing downwards in this :


This seems the perfect solution for me, assuming my passive radiator is suitable for downfiring.
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Old 15th October 2008, 06:44 AM   #6
Vikash is offline Vikash  United Kingdom
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Join Date: May 2003
Location: UK
I've always had it positioned sideways so both drivers are vertical.

I really should update that page...
"The human mind is so constituted that it colours with its own previous conceptions any new notion that presents itself for acceptance." - J. Wilhelm. (But I still think mine sounds better than yours.)
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Old 15th October 2008, 09:14 AM   #7
diyAudio Member
Join Date: Mar 2006
Location: Cheshire
BK Electronics uses this Passive Radiator facing downwards.

This is good enough encouragement for me, so I am going to give it a go.

If you think about the mechanics of a PR, perhaps this is the best way to go?

Thanks for your help. I will keep you posted...
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