After about 3 weeks of construction, I am ready to drill my holes for my new nearfield monitors. ... I just had a question for anyone who might know. I do not have a router, and was considering just mounting the speakers front mounted... but someone said I should use felt if I do front mount the speakers, but if I make a route and flush mount them, do I still need this felt?
Also, In an optimal prism cabinet design... is there an optimal speaker placement, or do I just measure the distance I have left over after C2C alignment, then halve it and place the speakers there... Bottom <-- Measurement --> Mid/woofer <-> Small Gap using calculated C2C <-> Tweeter <-- Measurement --> Top... as such?
Here's a picture of the best cabinets I have ever constructed. I am completely 100% happy with my work.
Sorry about the bad focus, lol. It was a last minute Cameraphone picture.
Also, In an optimal prism cabinet design... is there an optimal speaker placement, or do I just measure the distance I have left over after C2C alignment, then halve it and place the speakers there... Bottom <-- Measurement --> Mid/woofer <-> Small Gap using calculated C2C <-> Tweeter <-- Measurement --> Top... as such?
Here's a picture of the best cabinets I have ever constructed. I am completely 100% happy with my work.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Sorry about the bad focus, lol. It was a last minute Cameraphone picture.
The felt is used to build the front baffle up to meet the edge of the driver, in order to minimise diffraction. If you flush mount the driver, you don't need to use it on the front baffle, although it won't hurt to use it to line the inside walls.
As for driver placement: off centre is best. Typically a little above centre vertically, a little left of centre on one speaker and a little right of centre on the other.
As for driver placement: off centre is best. Typically a little above centre vertically, a little left of centre on one speaker and a little right of centre on the other.
take the time to find natural wool felt. Any percentage of synthetic will not sound as good as 100% pure wool. The absorption of synthetic felt is not as wide band nor as uniform as that of natural wool.
Well, I might take the cabinets down to Bunnings one day and ask if some wood guy there can route the speaker holes down for me so I can flush mount, ... shouldn't cost me too much, there'd have to be someone there who would/could do it.
With the damping/lining the natural wool felt you mention... any particular thickness, do I just put it on the back panel, the sides, and bottom and top... but not the inside of the baffle?
With the damping/lining the natural wool felt you mention... any particular thickness, do I just put it on the back panel, the sides, and bottom and top... but not the inside of the baffle?
if you are building a sealed cabinet then yes you could line the five wall all over. How much thickness is a loaded question as it will depend upon the density of the felt but a good starting ponit would be 3/8 of an inch thick and work up from there. In a sealed sub cabinet you could easily use an inch of felt. You might try experimenting with a blanket layer of felt 1/16 inch thick in the centre of the cabinet dividing the cabinet in two. That may have to end up just at the rear of the woofers magnet assembly.
Blanket Layer of 1/16" Felt... mmm all these ideas make me end up with no idea at all. lol.
I'll read up more about felt and damping and stuff I guess.
I still don't have any internal bracing inside the cabinet, but it's an MDF Sandwich, 32mm baffle, 24mm everywhere else. It seems pretty sturdy so far.
I'll read up more about felt and damping and stuff I guess.
I still don't have any internal bracing inside the cabinet, but it's an MDF Sandwich, 32mm baffle, 24mm everywhere else. It seems pretty sturdy so far.
So, the speakers alignment should be kinda like this ... ?
An externally hosted image should be here but it was not working when we last tested it.
Hi,
i guess what TheSeekerr meant was to build the speakers pair-symmetric.
To have both drivers (woofer and tweeter of one speaker) centers in a
vertical line (and as near together as possible) is advantageous.
But that line should be off center, preferably in an incommensurable
relation of left and right distance.
Same applies to the vertical distances Woofer-Bottom and Woofer-Ceiling.
Kind Regards
i guess what TheSeekerr meant was to build the speakers pair-symmetric.
To have both drivers (woofer and tweeter of one speaker) centers in a
vertical line (and as near together as possible) is advantageous.
But that line should be off center, preferably in an incommensurable
relation of left and right distance.
Same applies to the vertical distances Woofer-Bottom and Woofer-Ceiling.
Kind Regards
So everything should be basically... centered? Joy. I'll make some final adjustments then cut the holes in the morning. I have no measuring equipment to find out how good this will sound when I'm done. But I'm guessing... awesome.
I'll place the mid/woofer and tweeter centres symetric to each other... then centre both in the box centre, then move that centre up about 5mm, and right about 5mm... or left for the other speaker. Sounds good?
As far as the felt goes, I'll assume to try and source some 3/4" for all the interior walls and see what happens when I get more to that part in a few days.
I'll place the mid/woofer and tweeter centres symetric to each other... then centre both in the box centre, then move that centre up about 5mm, and right about 5mm... or left for the other speaker. Sounds good?
As far as the felt goes, I'll assume to try and source some 3/4" for all the interior walls and see what happens when I get more to that part in a few days.
Hi,
5 mm is nothing. There has to be a significant ratio
left dist / right dist <> 1 and
top dist / bottom dist <> 1
avoid commensurable ratio like 1/2 1/3 choose
incommensurable ones
e.g. Golden ratio - Wikipedia, the free encyclopedia
Remark: Your front baffle is very thick. That can cause the
free area behind the cone to be much smaller than the cone
surface. It is narrowed from
1. driver basket
2. baffle hole and
3. magnet.
Such a volume enclosed behind the driver can resonate like
a "BR box in the box" (helmoltz resonator) whith resonance
typically somewhere in the midrange. A conical shape of the
baffle whole, which gets wider inside the box is preferable
to minimize this.
Easier to manufacture before box is put together ... since with
wide conical shape there have to be some kind of bridges for the
mounting screws.
With a layer of sheep wool fixed behind the the driver basket
those resonance effects can be minimized and additionally the
damping of the bass - resonance Qts can be controled by
thickness and density of the layer.
An air permeable cloth can be used to prevent fibers of wool
intruding into the driver.
Kind Regards
5 mm is nothing. There has to be a significant ratio
left dist / right dist <> 1 and
top dist / bottom dist <> 1
avoid commensurable ratio like 1/2 1/3 choose
incommensurable ones
e.g. Golden ratio - Wikipedia, the free encyclopedia
Remark: Your front baffle is very thick. That can cause the
free area behind the cone to be much smaller than the cone
surface. It is narrowed from
1. driver basket
2. baffle hole and
3. magnet.
Such a volume enclosed behind the driver can resonate like
a "BR box in the box" (helmoltz resonator) whith resonance
typically somewhere in the midrange. A conical shape of the
baffle whole, which gets wider inside the box is preferable
to minimize this.
Easier to manufacture before box is put together ... since with
wide conical shape there have to be some kind of bridges for the
mounting screws.
With a layer of sheep wool fixed behind the the driver basket
those resonance effects can be minimized and additionally the
damping of the bass - resonance Qts can be controled by
thickness and density of the layer.
An air permeable cloth can be used to prevent fibers of wool
intruding into the driver.
Kind Regards
Last edited:
Hi dave,
kindly you see after that ...
i would have preferred a vertical "in line" arrangement of
woofer and tweeter.
Since this is to be a nearfield monitor, with your 45 degree
arrangement one is free to put the speaker vertically or
horizontally and get similar dispersion in both positions.
Is this what you intended ?
Or just increase of asymmetry for the tweeter ?
Kind Regards
kindly you see after that ...
i would have preferred a vertical "in line" arrangement of
woofer and tweeter.
Since this is to be a nearfield monitor, with your 45 degree
arrangement one is free to put the speaker vertically or
horizontally and get similar dispersion in both positions.
Is this what you intended ?
Or just increase of asymmetry for the tweeter ?
Kind Regards
Damn, I knew i'd mess something up, lol. I was told the thicker the baffle the better. The more I design and research, the more I realise how rediculous my speakers are, lol.
I have heard of the Golden Ratio many times and never thought to relate it to the
positioning of speakers in a cabinet. That's awesome.
So I can use the vertical/horizontal in line arrangement for the woofer/tweeter... then... use the golden ratio to ... do something. lol
Well, I'll give dimensions. The interior is ... 392mm x 241mm x 141mm ... 14 Litre. And I'm using the Vifa P17WJ-00-08 & Vifa D27TG-45-06 ... so 6 inch mid/woofer, into the 14 litre cabinet.
I have heard of the Golden Ratio many times and never thought to relate it to the
positioning of speakers in a cabinet. That's awesome.
So I can use the vertical/horizontal in line arrangement for the woofer/tweeter... then... use the golden ratio to ... do something. lol
Well, I'll give dimensions. The interior is ... 392mm x 241mm x 141mm ... 14 Litre. And I'm using the Vifa P17WJ-00-08 & Vifa D27TG-45-06 ... so 6 inch mid/woofer, into the 14 litre cabinet.
Golden ratio is not the "last wisdom" i merely mentioned it to serve
as an example for incommensurable ratio.
But it is widely used in acoustics (Aspect Ratio of rooms, positioning
of speakers).
If damped sufficiently and not made from lightweight and stiff material,
there is nothing wrong with a thick baffle, but the rear free area has to
be kept in mind.
If you make a route for the front mounted woofer-
which makes the baffle thinner effectively -
and make some conical cuts in 1/4 circles between the
"flesh" you need for the screws on the inner side,
the problem should be solved.
Kind Regards
as an example for incommensurable ratio.
But it is widely used in acoustics (Aspect Ratio of rooms, positioning
of speakers).
If damped sufficiently and not made from lightweight and stiff material,
there is nothing wrong with a thick baffle, but the rear free area has to
be kept in mind.
If you make a route for the front mounted woofer-
which makes the baffle thinner effectively -
and make some conical cuts in 1/4 circles between the
"flesh" you need for the screws on the inner side,
the problem should be solved.
Kind Regards
If my calculations are correct, Internally, I have 119mm top and bottom to work with vertically, and 72mm to work with left and right horizontally... if speakers are touching. But they will have about 7mm between mid/woofer & tweeter.
Every studio monitor I can see online just with a quick search on google, the mid/woofer and tweeter appear to be centered vertically, and aligned where space suits, horizontally... ? I have not seen one yet where the mid/woofer is slightly off centre... are they all badly designed or something? Some have an off centre tweeter... but generally, not. I don't get it.
Woops, I made a mistake, my front baffle is 28mm thick, not 32mm. It's 16mm + 12mm Sandwich, not 16mm + 16mm, ... does that make it any better being 28mm instead of 32mm?
Hi there, just estimate the free area behind the cone to get a picture.
Thickness itself is not an issue
So i guess
392mm x 241mm x 141mm is Height x Width x Depth ?
Proposals:
Division in height:
392 X 0.618 = 242 (242:150)
392 x 0.707 = 277 (277:115) X
Division in width:
241 x 0.618 = 149 (149:92)
241 x 0.707 = 170 (170:71) X
From my gutt feeling these would be some proportions to consider,
surely not the only ones possible.
The golden mean division in height would give distance
of 242mm from woofer to bottom or top, which is close to
the width of the box.
Same in width: Golden mean would result in a side wall
distance close to depth of the box.
So i would prefer the cross marked options (ratio 1/2^0.5).
These are my "gutt" feelings, no science, it is possible to
optimize aspect ratios and distances using modal analysis.
When applied:
The space from the woofer cutout to the closest wall should
still be sufficient for a 360 degree conical shaping of the
woofer cutout ??
The tweeter should be placed on the longer vertical
division near the woofer. Are the distances from the tweeter's
center to the 3 nearest edges (top, left, right) still different
and incommensurable ?
Your cabinet is rather incommensurable (height/witdh near golden ratio)
and with appropriate damping should have little coloration from
modes inside the cabinet.
Finally:
Consider "soft mounting" of the woofers using e.g. felt ring
between basket and baffle, rubber dampers behind srcew heads
to lower direct mechanical excitation of the cabinet.
Since the basket of the Vifa seems to be a stamped steel one,
consider filling the basket ribs with plastic kneading mass e.g.
do calm down basket resonances.
Consider using a felt blanket on the baffle around the tweeter as
mentioned before by others.
Consider reduction of coupling of speaker cabinet to the underground,
especially when this is a bookshelf or a table. A triple of thick
felt feet near the edges is normally is a cheap start.
Consider soft or swinging mounting of the crossover, use the
"calmest region" of your cabinet for mounting the crossover.
Prefer coils from backed wire or vacuum sealed ones (or coils from flat foil).
Consider damping of the plate resonances of the cabinet walls using
damping mats glued directly on the walls, like they are used to minimize
resonance in the automobile industry. Even a 2mm layer of such
bitumen / plastic mat is better than nothing.
(Germany : e.g. "Teroson" Lärmschutzmatten)
You can use a rubber hammer on the empty cabinet to observe the effect
of those measures (and measure the spectral content of the cabinet
sound if you like, but ears work too ).
Kind Regards
Thickness itself is not an issue
So i guess
392mm x 241mm x 141mm is Height x Width x Depth ?
Proposals:
Division in height:
392 X 0.618 = 242 (242:150)
392 x 0.707 = 277 (277:115) X
Division in width:
241 x 0.618 = 149 (149:92)
241 x 0.707 = 170 (170:71) X
From my gutt feeling these would be some proportions to consider,
surely not the only ones possible.
The golden mean division in height would give distance
of 242mm from woofer to bottom or top, which is close to
the width of the box.
Same in width: Golden mean would result in a side wall
distance close to depth of the box.
So i would prefer the cross marked options (ratio 1/2^0.5).
These are my "gutt" feelings, no science, it is possible to
optimize aspect ratios and distances using modal analysis.
When applied:
The space from the woofer cutout to the closest wall should
still be sufficient for a 360 degree conical shaping of the
woofer cutout ??
The tweeter should be placed on the longer vertical
division near the woofer. Are the distances from the tweeter's
center to the 3 nearest edges (top, left, right) still different
and incommensurable ?
Your cabinet is rather incommensurable (height/witdh near golden ratio)
and with appropriate damping should have little coloration from
modes inside the cabinet.
Finally:
Consider "soft mounting" of the woofers using e.g. felt ring
between basket and baffle, rubber dampers behind srcew heads
to lower direct mechanical excitation of the cabinet.
Since the basket of the Vifa seems to be a stamped steel one,
consider filling the basket ribs with plastic kneading mass e.g.
do calm down basket resonances.
Consider using a felt blanket on the baffle around the tweeter as
mentioned before by others.
Consider reduction of coupling of speaker cabinet to the underground,
especially when this is a bookshelf or a table. A triple of thick
felt feet near the edges is normally is a cheap start.
Consider soft or swinging mounting of the crossover, use the
"calmest region" of your cabinet for mounting the crossover.
Prefer coils from backed wire or vacuum sealed ones (or coils from flat foil).
Consider damping of the plate resonances of the cabinet walls using
damping mats glued directly on the walls, like they are used to minimize
resonance in the automobile industry. Even a 2mm layer of such
bitumen / plastic mat is better than nothing.
(Germany : e.g. "Teroson" Lärmschutzmatten)
You can use a rubber hammer on the empty cabinet to observe the effect
of those measures (and measure the spectral content of the cabinet
sound if you like, but ears work too ).
Kind Regards
What do you think ?
In the industry there seem to apply some rules of thinking:
1. Reduce cost no matter how !
2. We always done it this way !
3. An asymetrical speaker looks strange.
(Since our customers are deaf anyway they buy things by its look
and do not want things that look strange.)
4. Detail is not so important. Our speakers sound the best,
because the name of our brand is etablished and sounds good in
itself.
Variant:
"Our new Poly-Bull ... vapored woofer is so good,
that the mounting conditions are neglegible." 😛
5. ...
Do you want me to continue ? No Problem.
Human behaviour is mostly predictable and simple.
So are marketing strategies. 😀
Kind Regards
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