advice on drivers for IB sub - Page 2 - Home Theater Forum and Systems -

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post #11 of 15 Old 07-20-14, 04:42 AM Thread Starter
Join Date: May 2008
Location: wales
Posts: 11
Re: advice on drivers for IB sub

I had not considered the low frequency spec so thank you for pointing that out. I guess if I am going to the bother of building an IB sub I might as well try to get the most out of it.

I have copied the spec of another amp from "" which goes down to 15Hz and is rated at 1000w

I would be grateful for your comments, the spec is at the bottom of the post in bold.

The Extreme 1000 Sub Bass Amplifier -

The Extreme 1000 is our latest sub bass plate amplifier and it boasts a full 1000W RMS into 4 ohms and 2000W peak, delivered by a state of the art Class D amplifier.

Controls include High Level Volume, Low Level Volume, Filter By-pass, Low Pass Filter adjustable 40 to 120hz and a fully adjustable phase control.

Because this is such a powerful amplifier we have also included a high pass filter to protect the drive unit, this is set at 15Hz / 24dB Oct but can be adjusted within reason or removed. Please specify your requirement when ordering by using the comments box at the bottom of the order page.

By using a highly effecient Class-D amplifier typically 85% and and Auto On / Off circuitry the Extreme 1000 is energy effecient and comes with green credentials

Features :-

Phase Shift Continuously variable 0 - 180Deg
1000W R.M.S. Into 4 Ohms - 2000W Peak
High and Low level inputs with separate gain controls
Upper roll off is continuously variable between 40Hz and 120Hz
Filter Bypass switch, for use with sub outs from processors
Airtight construction
Auto standby feature
Short Circuit Protection
4mm Thick Aluminium Front Panel
15Hz high pass filter 24dB/Oct

The Extreme 1000 Inputs and Controls

High Level Input - Connects to amplifier speaker terminal
High Level Gain - Volume control for the High level input
Low Level Gain - Volume Control for the ow level input
Low Level Input - Connects to either a Stereo pre-amp or from the sub out from an AVR
Filter By-pass - By-passes the filter on the low level input without affecting the frequency setting on the high level input
Frequency Contour 40 to 120Hz - Sets the upper roll off of the subwoofer to match the lower roll of of the main speakers
Phase - Contiguously variable phase
Not all if any plate amplifiers have this level of connectivity and control. The Extreme 1000 can be connected to both an AVR and Hi-Fi amp simultaneously or it can be used to take advantage of "Pure Direct" modes

Output Power
BSBP 500/4
1000W RMS Into 4 Ohms
Frequency Response

15Hz to 120Hz
100dB A Weighted
0.05% Typ
Low Level Sens
High Level Sens
H334.1 x W223.5 x D70mm
Mains Voltage **
110/230V - 50/60Hz

The Extreme 1000 uses the latest Class D amplifier coupled to a switch mode power supply that can deliver 1000W RMS into a 4 ohm load and 2000W peak to cover the short periods of time to cover the reality of music.

The built in over current protection has two modes. During transients into the current limit threshold it allows constant output current but if this condition persists it goes into burst mode. This guarantees that the amplifier does not create audio holes during heavy listening but still effectively protects it during short circuiting. The thermal protection is by a sensor connected to the very tab of one of the output devices giving a very fast detection and shut down should overload occur.

(c) 2014 BK Electronics - Unit 1 Comet Way, Southend-On-Sea, Essex SS2 6TR - Tel ; 01702 527572 email
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post #12 of 15 Old 07-22-14, 12:25 AM
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Re: advice on drivers for IB sub

Well, my ‘knee jerk’ response is that 15 Hz is still too high by at least an octave since there’s a number of movies with near DC BW, but then I’m spoiled by my decades old then SOTA amps with measured responses of < -3dB/1 Hz in their TEST mode and ~ -3 dB/5 Hz in NORMAL mode, which on the face of it was only strictly of use to marketing dept.’s since there were only a few RTR recordings that had down to 16 Hz and even then at something like –10 dB………..

I imagine such amps are available these days of course, though this is the only one I could find in a semi-quick search with a lower cut-off and disappointed that it doesn’t go as low as some of their previous amps:

Like mine at the time of purchase, it consumes mass quantities of ‘coin of the realm’ to acquire, so instead I’m thinking that maybe a [sub] amp’s BW should be chosen based on the lowest frequency in a recording that is –40 dB, the outer limits of our hearing ‘envelope’ [perception] and maybe even only at –25 dB where we’re below the ‘noise floor’ of our speech intelligibility perception.

Still, the main thing I’ve learned in ‘chasing’ ever lower [wider] BW is that as more LF is added [even synthesized if properly done] I perceive the rest of the BW as sounding ‘fuller’, more extended in the HF, i.e. more ‘live’, though I know of course that nothing in the recording has changed, just my perception of it, so reproducing as much of it as practical seems the goal.

In short, the BK seems a fine amp, but will it meet your long term BW needs or will the budget rule?


Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
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post #13 of 15 Old 07-22-14, 08:48 AM Thread Starter
Join Date: May 2008
Location: wales
Posts: 11
Re: advice on drivers for IB sub

Thanks again for that

I see the BK site has a lower power(500w) amp that goes down to 3Hz which might be more suitable.

wow, able to post links now!

I have a couple of vintage amps a lux and a pioneer I might try as an experiment, not sure if I could tailor the output to suit the speakers.

I have an ATC active set up with C6 sub so don't have a high end power amp.
This is abit of an experiment - I listen to music much more than film - I guess I could always change the amp further down the line if a BK one does not do the business!
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post #14 of 15 Old 07-22-14, 05:10 PM
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Re: advice on drivers for IB sub

You’re welcome!

Awesome! 3 Hz in a plate amp, but where can I buy one and at what price? This is a ‘no brainer’ for me, but the trade-off is more drivers will be required to get efficiency up to compensate for the lower power.

So, is it time to talk drivers yet?


edit: Why isn't this in the IB forum?

Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

Last edited by GPM; 07-22-14 at 05:48 PM.
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post #15 of 15 Old 07-23-14, 12:42 AM Thread Starter
Join Date: May 2008
Location: wales
Posts: 11
Re: advice on drivers for IB sub

I did not realise there was an IB specific forum.

the only IB specific drivers I have found in the UK are the Fi IB3 range 15 or 18 inch, I think I should be able to fit in the 18 inch x 2 - I have limited space in the attic.

there are some UK 15 inch speakers from volt which might be ok - not sure they have enough cone movement to suit an IB though.
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