I recently build two hyper bass reflex speakers according design H08F from @nandappe.
These are 30cm high, 14,6cm wide and 20cm deep enclosures.
I had a couple of beautiful oak boards lying around that were 14 cm wide and 2cm thick. I decided to use these for the sides and top, while I cut 12mm boards from a pine beam to make the front baffle, the back and all internal baffles.
Glueing the oak boards an getting all boards flat with the correct thickness was quite a challange without a thicknesser or jointer, but I managed quite well with accurate working and lots of sanding.
I had to adapt the design in details to get the desired look, especially on the top panel, but I made sure all internal dimensions did not change.
I used a 3 inch driver, the Peerlees P-830986.
I don't have a proper set-up for sound measurements, although I did measure the impedance curve the old fashioned, primitive way. So, testing and making adjustments was all by ear.
I experimented with damping material. At first I did not have felt mats, but instead used Dr. Baileys longhair as a filling in the chamber behind the driver. Unfortunately the sound was boomy and that did not change too much with the wool filling. I could then buy 5mm felt mats locally and put these in the chamber behind the driver, as per the design. This turned out to be much better, but the boominess did not disappear enough and sound was still quite muddy.
As a next step I started changing the duct/port dimensions of the enclosure. I added thin boards in the duct to make the port smaller as to lower the resonance frequency, which was originally around 104 Hz. I finally settled to almost halve the port height. The resonance frequency of the port changed from 104Hz to 78Hz, boominess disappeared, bass got deeper and the sound in general got cleaner, with much better definition.
I finally also added felt on one side of the biggest back chamber to dampen possible resonances there between the parallel walls. This did not change much, but I kept it there anyway.
Altogether I'm quite pleased with the result. Of course there is no real, deep bass and even in comparison with my mini-transmssion line speakers (2 way, 22liter) bass, with some music, feels totally lacking. But for such a small single driver the sound is simply amazing, seemingly full with proper lows and all together very nice and pleasant to listen to.
Some pictures showing the build and final result.
Glueing the internal baffles:
Slowly getting there:
Ready for testing:
The final result, finished with linseed oil:
These are 30cm high, 14,6cm wide and 20cm deep enclosures.
I had a couple of beautiful oak boards lying around that were 14 cm wide and 2cm thick. I decided to use these for the sides and top, while I cut 12mm boards from a pine beam to make the front baffle, the back and all internal baffles.
Glueing the oak boards an getting all boards flat with the correct thickness was quite a challange without a thicknesser or jointer, but I managed quite well with accurate working and lots of sanding.
I had to adapt the design in details to get the desired look, especially on the top panel, but I made sure all internal dimensions did not change.
I used a 3 inch driver, the Peerlees P-830986.
I don't have a proper set-up for sound measurements, although I did measure the impedance curve the old fashioned, primitive way. So, testing and making adjustments was all by ear.
I experimented with damping material. At first I did not have felt mats, but instead used Dr. Baileys longhair as a filling in the chamber behind the driver. Unfortunately the sound was boomy and that did not change too much with the wool filling. I could then buy 5mm felt mats locally and put these in the chamber behind the driver, as per the design. This turned out to be much better, but the boominess did not disappear enough and sound was still quite muddy.
As a next step I started changing the duct/port dimensions of the enclosure. I added thin boards in the duct to make the port smaller as to lower the resonance frequency, which was originally around 104 Hz. I finally settled to almost halve the port height. The resonance frequency of the port changed from 104Hz to 78Hz, boominess disappeared, bass got deeper and the sound in general got cleaner, with much better definition.
I finally also added felt on one side of the biggest back chamber to dampen possible resonances there between the parallel walls. This did not change much, but I kept it there anyway.
Altogether I'm quite pleased with the result. Of course there is no real, deep bass and even in comparison with my mini-transmssion line speakers (2 way, 22liter) bass, with some music, feels totally lacking. But for such a small single driver the sound is simply amazing, seemingly full with proper lows and all together very nice and pleasant to listen to.
Some pictures showing the build and final result.
Glueing the internal baffles:
Slowly getting there:
Ready for testing:
The final result, finished with linseed oil:
