DIY Loudspeakers: HOME INDEX UPDATES RESPONSE WHAT'S NEW Bass Module for
SBA-741 - and other small speakers |
Go to on this page: The bass module here is designed for the SBA-741 speaker, but it suitable for a wide range of "6+1"s, like:
Why a woofer and not a subwoofer? A subwoofer is really meant to assist in the 20-40 Hz range, maybe up to 60 Hz, but that's it and what smaller speakers need is really some help in the mid-bass to middle-bass are, 40-160 Hz, where most 6-7" drivers fail to deliver the punch and dynamics needed to assist the illusion of live music. 95-150 cm^2 (5-7" drivers) membrane area simply cannot move enough air. We can't all have ~150 litre cabinets with 15" bass driver, but we can have some of the goodies from smaller designs by choosing the right drivers. Good bass is about membrane area and efficiency - and an amplifier delivering the necessary amperes. As such, there are no sonic attributes linked to bass, it's all about moving as much air as possible - and moving it fast. And we can have most of it at reasonable price from using PA drivers and plate-amps. Had a mail recently where the writer had a friend stating PA drivers cannot be used for hifi. Nothing could be further from the truth. I still claim my The Loudspeaker is more hifi than any other speaker I've made, but it takes 300 litres.
Scanning the
Faital
portfolio for smaller bass drivers my eyes caught this 10" variant and
from this potent 600 watt bass driver and a plate-amp we can make smaller stand-mounts into something
better. And if we use a 1st order high-pass filter for the stand-mount as
suggested
here, even more so. From 40 litres volume we get -3 dB @ 40 Hz, not bad at all, but given the high power handling of the Faital driver, we can boost the low-end some additional dB to go louder and deeper. We do that in programming the Hypex FA251 plate-amp/DSP. On top of this we place the driver some 8 cm from the floor taking advantage of room-gain. Out on the floor we get +3dB room-gain over a wide frequency range and a theoretical -6dB @ 30 Hz. Not bad for a small speaker with fairly high efficiency. Example of the simplest set-up: You have a 6+1 and build the bass module. Install the Hypex software B and connect the Hypex input via a wire from the speaker terminals. Find some bass-heavy source material and adjust the bass to suit your taste and room conditions. That's all it takes. I'm sure I'll have the question whether this or that bass driver can replace the Faital. I cannot tell, so please do not ask.
Basics: Download specs: FAITAL 10RS350-8 This phenomenal bass driver is available from LEAN, UK for 95 £, equal to 108 EUR!
Download software A, B and C
here.
This is not a subwoofer, but a bass driver having Fs = 40 Hz.
This may seem a bit high, but capable of handling 600 watts we can make it do
the lows with the help of the Hypex DSP programming.
Software A: Low-level input
via balanced or SE cable from pre-amplifier with and without 1st
order high-pass filter before power amplifier. Read
here. Adding the 1st order filter to your power amp driving the main
speakers, seriously increase power handling.
If you have a vented 6+1 without using the
high-pass filter you may stuff the vent with acoustilux to get an
earlier roll-off and gain a little extra power handling by limiting the
6" bass driver from excessive excursion, but it doesn't prevent the
voice coil from receiving the full low-end signal.
*
Cabinets are made from 20 mm Baltic birch and 20 mm HDF. Follow images
below. Internal panels were added 4 mm bitumen pads and 8 mm felt.
Two pieces of 30 x 50 cm acoustilux is placed at bass cabinet top. See images below. I used 75 mm (71 mm ID) PVC pipe for the vents. In the kit below Ø7 cm ports are listed. Read about ports here. You can obviously use this bass module principle for a wide range of smaller speakers and do not have to make a pyramid like this one specifically made for SBA-741, but adjust the cabinet for whatever you may have on top. Any 38-42 litre cabinet made with the bass driver mounted as shown is suitable. You should not place the bass driver on the front or sides as you will loose room-gain and overall efficiency. Please check all items here before writing: http://www.troelsgravesen.dk/tips.htm Workshop images
Software A and B
KIT only available with
Hypex module
The bitumen pads are optional and must be added to your order. All kit and component prices may be subject to
change and are always to be confirmed by Jantzen Audio Denmark. Download Complete Kit Sale Presentations: All technical questions to troels.gravesen@hotmail.com All questions regarding purchase of kits, please mail Jantzen Audio at contact@jantzen-audio.com
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