Speaker boxes/cabinets

[disco_monkey79]

Hi
I am going to make new boxes for a pair of hifi speakers, to make them a little more interesting and in line with my decor (rather than their current faux black ash).

My question is this - the woofer is normally (always?) at the bottom, with tweeter above. Is this simply because it's sensible to put the heavier bit at the bottom? Or is there some audiophile/science-y reason for this?

I will be fixing them to the wall so that will ensure stability in any formation.

Thanks

 

[Spectric]

Firstly speakers are not just boxes with speakers in them, the science behind a speaker enclosure is quite complicated. This is a good application of MDF because of its density and the tweeters work at higher frequencies moving less air, the woofers working at low frequencies move a lot of air and can cause vibration / resonance and so having them on the wall may not be a good idea. Also a large woofer will move air on both the front and rear sides so this is where baffles and ports come into play so I would say you need to get a book on speaker enclosure design and have a look or find some online references.

 

[Ollie78]

@Spectric has said it all really. There is a lot of knowledge available for this sort of thing with calculators for the size of the drivers/ cones and how much baffling and porting is needed etc. Its been ages since I made any speakers but there was a forum I found with lots of information ( almost too much ) depending on how full nerd you want to get.

Might have been this one https://techtalk.parts-express.com/forum or AVS forum

Ollie

 

[ajs]

Yes many books have been written dealing exclusively with this topic. I would not claim any expertise myself. The only design I have ever studied is the legendary BBC LS3/5A (BBC design, produced by various manufacturers over the years), and that only because a replica design appeared in one of the electronics magazines a few years back. From memory both the original and that copy specify birch ply, other materials compromise the acoustics.

I'm in pub right now but when I get home I'll try to dig it out and PM you. Even if you ultimately decide (as I did) the specific design is a bit spendy for your tastes it'll probably give a better flavour of things to consider than I ever could.

 

[TRITON]

Firstly speakers are not just boxes with speakers in them, the science behind a speaker enclosure is quite complicated

Indeed. My cabinetmaking lecturer at college, during his career was making speakers for Linn(or it might have been Bang&Olufsen, (though Glasgow based so I think it was Linn). And i remember him saying at the time that they had to be made to extremely fine tolerances. I guess its the internal size that is very important.

Oddly enough there was a bloke I used to cycle with who's brother was a sales rep for Linn, and his brother had gifted him the set he took about to demonstrate. Speakers and amp, when the company models changed and them became basically obsolete.

Thats some gift, and this was high up the range stuff where the speakers are £30k a pop.

 

[Jacob]

Wilmslow Audio for top end stuff https://wilmslowaudio.co.uk/

 

[sploo]

My question is this - the woofer is normally (always?) at the bottom, with tweeter above. Is this simply because it's sensible to put the heavier bit at the bottom? Or is there some audiophile/science-y reason for this?

Low frequency drivers tend to radiate sound like a lightbulb illuminating a room (energy going in all directions). Higher frequencies however are "beamed" more like a spot light. With this, drivers tend to have worse off axis response than they do on axis (i.e. the linear distortion is usually better on axis).

As a result, it's generally a good idea to have the high frequency driver in a speaker roughly at your (listening) ear height; so certainly for floor standing speakers it makes sense to have the larger lower frequency driver mounted lower.

Baffle step and diffraction can also be an issue (affecting mid and high frequency drivers); such that a small baffle width (or very rounded baffle) can be advantageous. Again, it's just easier to make a larger/wider cabinet for the low frequency driver and have the higher frequency drivers in a thinner cabinet, mounted on top. Some of Troels Gravesen's designs have split cabinets, or cabinets that thin towards the top: https://www.troelsgravesen.dk/Diy_Loudspeaker_Projects.htm

There are speakers where the treble is mounted below the midbass driver; so it's not an absolute. As long as the treble is at the correct height, then the distance between the midbass and treble (and relationship between the treble and the baffle edges) is more important than whether the bass driver is above or below the treble.

But yes, big heavy bass drivers are probably best mounted at the bottom of the cabinet.

 

[sploo]

Wilmslow Audio for top end stuff https://wilmslowaudio.co.uk/

Still got some speakers from them that I bought (as drivers and crossovers) about 20 years ago. One pair has since migrated to a different enclosure with some custom made ports, but still using the original electricals.

 

[Etaf]

my dad used to work for HIFI makers as a cabinet maker - Kef & Rogers
the science and spec and testing that goes into cabinets and there construction are NOT basic boxes

The BBC monitors where produced by Rogers and they had a testing sound room , all very interesting , i got my mother-in-law the small bbc monitors and sounded great

Also the stands are also designed for the speakers .......

look forward to seeing some of the final designs

 

[aforjeh]

if they are just MDF with a veneer you don’t like could you not just remove the covering and re-veneer it to your taste?

I have some nice speakers that saw too much sun, and peeled themselves psrtially that I’d like to do this to…

 

[imageel]

As others have said, speaker design is quite complex and there are numerous designs used to overcome these physical limitations
This is an example - one of a never to be finished pair of open baffle design by the late Siegrfried Linkwitz

 

[HamsterJam]

Mission Electronics have a long history of building speakers with woofers above the tweeters.

 

[HamsterJam]

my dad used to work for HIFI makers as a cabinet maker - Kef & Rogers
the science and spec and testing that goes into cabinets and there construction are NOT basic boxes

The BBC monitors where produced by Rogers and they had a testing sound room , all very interesting , i got my mother-in-law the small bbc monitors and sounded great

Also the stands are also designed for the speakers .......

look forward to seeing some of the final designs

IIRC correctly there were two models produced by Roger’s for the Beeb.
LS5/9s and the smaller LS3/5s.

 

[Jake]

As others have said, speaker design is quite complex and there are numerous designs used to overcome these physical limitations
This is an example - one of a never to be finished pair of open baffle design by the late Siegrfried Linkwitz
View attachment 179181

How come never to be finished, or is that self-deprecating irony about slow progress? The (metal cone?) woofers have a very expensive air to them, what are they?

 

[Etaf]

IIRC correctly there were two models produced by Roger’s for the Beeb.

Yep thats what i remember
and still do, seem to be still trading , i thought they went out of business
https://www.rogers-hifi.uk/rogers-ls35a-classic-speakers

I like the spender BC1
And in the 90's looked at some signiture speakers not sure by who now - But about £2K a pair - last time i looked around the 8K

and also was looking into some electrostatic with a base unit around 2006

I settled in the 80's on the first produced BOSE Acoustimass , replacing some monitor audio speakers

I used to sell rogers stuff and a lot of other at a hifi shop in Welling london in the 70's
and had rogers AMP/Tuner and speakers myself
I had a thorens TD125 deck and sme arm V15 But wanted the Quad gear

 

[Agent_zed]

High end Hi Fi speakers might be different these days but there seems to be a lot of nonsense about about guitar speaker cabinets.

Take the marshall 4x12 cab for instance (https://www.musicradar.com/news/gui...-stack-the-birth-of-the-100-watt-stack-627421)

'
PW: “Jim came up with the idea of a full stack with the top cabinet angled, whereas the first 4x12 cabinets that we made were what we would class as ‘B’ cabinets - straight fronted because they were easy to make.

“People ask if the slanted cabinet was done to increase the spread of the sound, but initially, Jim did it because it looked nice - and I got that straight from him. I was talking to him about it and the angled cabinet on the 4x12 was done so that when you put the head on top, it didn’t just look like it was stuck on top; the angle made it look like the head was part of it.

“As it happened, when you played through it, because the top was angled back, the sound was pushed over the top of the audience and gave a bigger spread. Purely coincidental.”

Might be a bit more thought into it now but I don't hear many people complaining about how terrible a vintage marshall stack sounds (quite possible because they are deaf now from the 100watt amp driving them).

There will of course be differences depending on various design parameters but who is to say one piece of baltic birch plywood is the same as another piece, or that it sounds significantly better than some other bit of ply.

Given the sound quality you can get out of tiny bluetooth speaker these days I don't put too much stock into cab design. Get some decent speakers and a relatively tried and test cab design and give it a go, I bet it will sound good.

If you want to start a fight ask about what tone wood to make a guitar out of!

 

[Calum Bettison]

Hi
I am going to make new boxes for a pair of hifi speakers, to make them a little more interesting and in line with my decor (rather than their current faux black ash).

My question is this - the woofer is normally (always?) at the bottom, with tweeter above. Is this simply because it's sensible to put the heavier bit at the bottom? Or is there some audiophile/science-y reason for this?

I will be fixing them to the wall so that will ensure stability in any formation.

Thanks

If your speakers are a bass reflex and front ported design, and as long as you can get a proper secure fixing to your wall so the speaker enclosure can’t move/vibrate when in use, then this is actually good. It’s the same principle why people put spikes on the bottom of their floor standing speakers. Keeping the enclosure rigid in place allows all of the acoustic energy to radiate from the drivers, and not be wasted/distorted by being absorbed by a freely vibrating box.

The other main thing to be aware of if mounting to a wall is that the bass response will be exaggerated. This is because the omnidirectional low frequencies don’t have anywhere to travel behind the speaker, so end up being squashed forward, effectively doubling the sound pressure level. If you have an eq on your amp this would help to sort that out.

 

[sploo]

As others have said, speaker design is quite complex and there are numerous designs used to overcome these physical limitations
This is an example - one of a never to be finished pair of open baffle design by the late Siegrfried Linkwitz
View attachment 179181

Linkwitz was an amazing guy. Had the pleasure of speaking with him a few times, and attending one of his presentations at the Audio Engineering Society.

 

[imageel]

Linkwitz was an amazing guy. Had the pleasure of speaking with him a few times, and attending one of his presentations at the Audio Engineering Society.

You were lucky, I only exchanged a few emails with him back in 2013 and would have loved to have met him, he was an incredibly talented guy

 

[sploo]

I have some of the Scan-Speak 21W/8554 drivers he used in the Phoenix open baffle design (actually originally from a ported box design - Nemesis - from Wilmslow Audio) that I keep meaning to make some open baffle speakers. Never get time to do it though.