Being really impressed with the clarity and resolution of my newly purchased Yamaha NS-1000 meant that the next logical step
was to investigate ways improving the bottom end response; as this was
the only thing that was bothering me with these speakers.
Manufacturer’s specs show the frequency response from 40Hz. I have run some
'near-field' measurements (approx. 60mm from the diaphragm due
to the driver grille) which resulted in -6dB at 40Hz.
My goal was to get frequency response from
around 30Hz with -6dB.
I’ve seen number of threads on various forums related to getting more bass from NS-1000, but I have not found anything appealing there. Couple of people reported good result from
removing large amount of damping material but I have not had much success with this. Removing damping from behind the woofer slightly altered the bass
sound but I would not say that it made it any deeper. Removing damping material decreases virtual enclosure volume, and therefore, purely from
theoretical point of view, should result in less deep bass.
I’ve also come across some photos, where a person built a set of subwoofers (one under each speakers),
however, this was not the direction I wanted to go.
Blending external subwoofers with speakers is not always easy and I
simply did not fancy doing it.
I’ve found T&S parameters of the Yamaha’s bass drivers on Troles Gravensen’s website, which indicated that
the bass driver is quite ‘flexible’, in a sense
that it can be used in a bass-reflex enclosure. I’ve then measured T&S parameters of my
own drivers and the results were quite similar to the results
published by Mr Gravensen. This encouraged me to experiment with different enclosure types and sizes. After simulating number of different options,
I’ve considered increasing enclosures’ volume but keeping them sealed.
However, to get the bass response I was after, I’d have make 200 litres enclosures,
and this was not the best option for these drivers. I’ve decided that I will achieve best results from ported enclosures with volume between 70 and 110 litres.
The original enclosures were about 45 to 50 litres in volume, which meant that I had to make larger enclosures. Usually, I would start from scratch,
however, I was so impressed with built quality of the NS1000 that I decided to incorporate them into my design. The most logical option was to build
extensions underneath the speakers and by doing so, convert them into floor-standers.
Before doing any ‘proper’ work, I’ve cut out two holes at the bottom of one speaker and mocked-up an extension from spare pieces of chipboard.
I’ve measured bass driver’s impedance in the enclosure and tuned the port to the desired resonance frequency.
Interestingly, the woofer's 'near-field' measurement, apart from
deeper bass extension, also shown a couple of decibels increase
in the 60-110Hz range. Most likely, result of the increased
enclosure size and lack of heavy mineral wool damping behind the
This did not put me off, as couple of decibels is a drop o water
in the ocean, if you consider what happens to frequency response
in our hardly optimised listening rooms...
I have then compared both speakers (original vs. extended) in mono.
The results were very encouraging. The bass was much deeper than in the original
speaker and surprisingly, I did not perceive it as ‘slow’. I was slightly concerned that adding extra bass will affect my perception of midrange and
treble clarity (it is quite common that we perceive speakers will less bass as more detailed). However, this was not the case with
Extending frequency response did not harm midrange or treble in any way. When two speakers were compared side by side, the extended one sounded like the
original speaker in all aspects except the bass - it was much deeper.
Based on these very positive results, I’ve decided to convert my NS-1000 into floor-standers with a volume of 75 litres and resonance frequency of 30Hz.
Because my original enclosures were in pretty bad visual
shape, I’ve decided to sand all the paint off and glue 3mm thick
MDF all around the enclosures, except from the backs, where the
10mm MDF would go (I am not going to give any precise
measurements of the MDF panels here as these very much depend on
how much material you are going to sand off from the original
enclosure and how are you are going to join them together).
The work started form preparing original enclosures.
Unfortunately mine were used and abused during their previous
life, and as a result of multiple knocks, the side walls were
not perfectly flat. I had to improvise and create rails
(parallel to the side of the speaker), that I could slide my
router on. This way, router bit removed the material only from
the areas where there was an excess of it.
Afterwards, the enclosures were sanded using belt sander and 40
grit sand paper. If I was going to apply finish directly onto
existing enclosures I would have not used the belt sander. But,
I was going to glue thin MDF panels around the speaker, so
slightly uneven surface did not matter that much.
Plastic clips for holding grills were removed together with any
black paint remaining in the holes, to ensure good filler
adhesion. The black paint was also removed from any other areas
where I knew I was going to apply glue (driver
I’ve used spare pieces of 6mm plywood and router with
a trimming bit (one with ball bearing at the bottom) to make the
- Jig for routing out holes at the bottom of enclosures
- Jig for routing out speaker terminal inner hole
- Jig for routing out speaker terminal recess.
The bass extension box was made from 25mm thick MDF.
Designed with removable bottom panel, hence the captive
nuts and bolts visible on the photos. Extension box was
glued and screwed together with original speaker. Any gaps were
filled in using wood filler.
The trimming router bit was also used to cut out front panels
Adding new 3mm thick front panel meant that I needed to create
3mm washers to raise the drivers and attenuators. The easiest
way of making these (at least in my mind) was to use previously
cut out front panels, and draw the appropriate shapes on a
pieces of 3mm MDF. Once the shapes were drawn, they were cut out
using jig-saw and miniature table saw. Not perfect but
close enough. The shapes were then put into speakers and their
centre bits were routed out using the trimming bit. The speaker mounting holes were marked and drilled out
using bench drill.
Having all the washers ready, created perfect
opportunity for cutting out drivers’, attenuators’ and speaker
The speaker terminal holes on the back of the
original enclosures were sealed with MDF & chipboard
10mm MDF panels were glued on the back of the speakers. Once dry, sides
were trimmed using the trimming router bit. New speaker terminal
cut out at the bottom of the speakers using previously prepared
jigs and standard router bit. 3mm MDF side panels were then glued to
each speaker side and once dry, trimmed with the trimming
router bit. The MDF panels were glued to the top of the speaker
and trimmed in the same manner as other panels.
front panels were ready to be glued on. This part was a little
tricky as the speaker holes in the panels were already cut out, so they needed
to be perfectly aligned with the holes on the actual enclosures.
Once the glue dried, the sides were trimmed with the
In addition, router was used to slightly chamfer all the
edges, making them look neat and much easier to paint.
Previously made, 3mm washers were glued into speakers' holes and any gaps were
filled in using wood filler. All of the open MDF edges were
sanded using various grit sandpapers finishing with 600 grit.
The enclosures were then primed using MDF primer, which sealed the
rather ‘thirsty’ MDF.
Before routing out the bass-reflex holes I decided to double
check if my simulations were correct by measuring speaker
impedance with the appropriate port lengths in. Once happy that
the tuning frequency is actually lower than I needed and that I
can up it by making the ports shorter, I routed out the wholes
in the speaker enclosures.
Enclosures were then taken to my friend's garage, where couple
of coats of self-levelling filler were applied. These were
followed by hours of sanding with wet and dry sandpaper. When
relatively flat surface was achieved, thin layer of black base
coat was applied. The enclosures were then lightly sanded to
remove the thin black coat. By doing so, any imperfections like
small dips became clearly visible. The imperfections were filled
in and couple of coats of black base layer were applied. Next, couple of coats of clear lacquer
were applied, to
achieve the desired glossy piano finish. Once lacquer was
applied, the speakers were left to dry for couple of weeks, to
ensure that the lacquer has hardened properly before polishing.
Polished enclosures were collected from my friend's garage
and taken to my workshop. All of the components were put in
place and all of the connections were soldered. Final
measurements were conducted to double check everything.
Overall, I am very happy with the results. I
have managed to preserve the original character of the NS-1000
and add extra 'oomph' at the bottom end. Exactly what I
List of Components & Prices
Table below shows list of the parts together with prices,
necessary to build the enclosures as described
Total Time: 70h (excluding paint work)
Total Cost: £338.23
||Price Per Unit
MDF For Bases
|MDF For Enclosures'
|Wicks MDF Primer
||Quick Dry, 750ml
|No Nonsense PVA Wood Adhesive
||M6 x 60mm
||M6 x 9mm
||ø19mm x 10mm
|Monacor MDM-3 Damping