Building my own speaker boxes
Discussion
Hello all,
About 5 years ago i was given some old Castle Bookshelf speakers. The tweeters and crossovers were fine/excellent, but the foam seals on the mid-range/bass cones had gone completely, so i took the speakers apart and rebuilt them with some new speaker units. I can't remember where i bought them from but they were decent ones (circa £120 a pair iirc).
When re-assembled they were tested on my dads set up and they were comparable to his Linn Ninkas playing an SACD, albeit lacking a little in the bass department, not an issue really as they are only used for music and not wanted for bass usage. To say i was very pleased with them was an understatement. They really are fantastic little speakers and sound much bigger and much more expensive than the total outlay.
Unfortunately, now, the veneer on them has cracked and almost entirely peeled off and they are looking very sad, although they still sound great. I was thinking about transferring all the electrics into a new box of my own design and manufacture. Fortunately i have access to a fair amount of tools and machinery so can make them almost any shape i wish, but i would like them to remain as bookshelfs.
I was thinking of going for a layered ply manufacture, but i am unsure of a few things.
If the internal volume and the air port are the same size as the original, will they sound the same?
or does the shape of the internal volume matter as well?
so, what to do?
I am a designer, but i don't want to f
k up the sound of them just to make them look beautiful.
i was thinking something along the lines of these:
or a mini version of these
About 5 years ago i was given some old Castle Bookshelf speakers. The tweeters and crossovers were fine/excellent, but the foam seals on the mid-range/bass cones had gone completely, so i took the speakers apart and rebuilt them with some new speaker units. I can't remember where i bought them from but they were decent ones (circa £120 a pair iirc).
When re-assembled they were tested on my dads set up and they were comparable to his Linn Ninkas playing an SACD, albeit lacking a little in the bass department, not an issue really as they are only used for music and not wanted for bass usage. To say i was very pleased with them was an understatement. They really are fantastic little speakers and sound much bigger and much more expensive than the total outlay.
Unfortunately, now, the veneer on them has cracked and almost entirely peeled off and they are looking very sad, although they still sound great. I was thinking about transferring all the electrics into a new box of my own design and manufacture. Fortunately i have access to a fair amount of tools and machinery so can make them almost any shape i wish, but i would like them to remain as bookshelfs.
I was thinking of going for a layered ply manufacture, but i am unsure of a few things.
If the internal volume and the air port are the same size as the original, will they sound the same?
or does the shape of the internal volume matter as well?
so, what to do?
I am a designer, but i don't want to f
k up the sound of them just to make them look beautiful.i was thinking something along the lines of these:
or a mini version of these
You need someone with specific knowledge of this as enclosure design can get very techincal indeed.
However - from what i understand (and i have only ever built enclosures for Subwoofers - not full range speakers) as long as you do not change the internal air volume of the enclosure and the internal air volume (size/area) of the port, you shouldnt be changing the sound if you are using similar materials to build the enclosure.
Things that *may* affect the sound and you might want to look into -
Hopefully someone who has more specific experience than me can comment and point you in the right direction.
R.
However - from what i understand (and i have only ever built enclosures for Subwoofers - not full range speakers) as long as you do not change the internal air volume of the enclosure and the internal air volume (size/area) of the port, you shouldnt be changing the sound if you are using similar materials to build the enclosure.
Things that *may* affect the sound and you might want to look into -
- The material used, and its inherent resonance, and the thickness of that material, may have a bearing on the sound - although im really not sure how detectable or to what extent this might effect it.
- Even if the overall volume and size of the port is the same as the original - you will need to be careful to ensure that the air flows the same - people go to great lengths to ensure that air flows well through ports if corners are involved for example. Even if the port is of the same volume and displacement you might not change the sound of the speaker it is damping, but you could introduce port noise (normally if a port is too small in diameter for the speaker it damps, or if it is not long enough).
Hopefully someone who has more specific experience than me can comment and point you in the right direction.
R.
slomax said:
When re-assembled they were tested on my dads set up and they were comparable to his Linn Ninkas playing an SACD, albeit lacking a little in the bass department, not an issue really as they are only used for music and not wanted for bass usage.
What sort of music do you listen to? A good recording of Verdi's "Requiem" will test the bass of any system not to mention the deep notes from the big pipes of a church/cathedral organ.slomax said:
If the internal volume and the air port are the same size as the original, will they sound the same? or does the shape of the internal volume matter as well?
If your original speakers were fully enclosed (infinite baffle) I would say that you would have little problem providing the internal volume remained the same, especially as you want a curved structure.The addition of the hole (reflex port) adds extra complications. The size and position on better quality speakers is designed to improve the lower frequency response. A quick Google came up with this page at Salford University which gives o good idea of how loudspeakers work.
One thing to consider is the more dense the material you make the "box" out of the better. I vaguely remember a series of articles building a HiFi system many years ago where the large speaker cabinets had an inner and outer skin with a 3" space between them. Once the speakers were in position the cavity was filled with sand, vitually free from all possible resonances.
Thanks FTP,
certainly food for thought.
I listen to quite a wide range of music to be honest. It's mostly modern chilled house/liquid d&b, but never really felt them lacking too much, although i do often listen to jazz and vocal music too (Bowie, Blur, Radiohead etc) too. I think if i needed any more range though i would build/buy a subwoofer instead of going bigger, i don't have much room to accommodate bigger/floorstanding speakers.
The current housings have are veneered MDF with (i would guess) a 4cm port at the bottom front, right in the middle, that goes through the casing and maybe continues straight with no coning for 2-3cm before stopping, with sound wadding beyond that.
My thought was that if i create the ply closure with each piece having a holes in exactly the same position i could glue it all together and then bolt it with threaded rods..... thoughts on this?
I would hazard a guess that they are Castle Trent's
they certainly look exactly the same!
certainly food for thought.
I listen to quite a wide range of music to be honest. It's mostly modern chilled house/liquid d&b, but never really felt them lacking too much, although i do often listen to jazz and vocal music too (Bowie, Blur, Radiohead etc) too. I think if i needed any more range though i would build/buy a subwoofer instead of going bigger, i don't have much room to accommodate bigger/floorstanding speakers.
The current housings have are veneered MDF with (i would guess) a 4cm port at the bottom front, right in the middle, that goes through the casing and maybe continues straight with no coning for 2-3cm before stopping, with sound wadding beyond that.
My thought was that if i create the ply closure with each piece having a holes in exactly the same position i could glue it all together and then bolt it with threaded rods..... thoughts on this?
I would hazard a guess that they are Castle Trent's
they certainly look exactly the same!
Using layered ply as per your first image is a great plan and certainly likely to improve on the original cabinet. Keeping the internal literage and port dimensions the same is important if you want to keep the sound the same as you have now. The port to bass driver geometry should be kept the same as currently too if possible.
You'll have noticed many commercial speakers using curved cabinets, spherical mid enclosures, radiussed edges etc etc and you now have the opportunity to do this with your new enclosures.Curved shapes are stronger than straight ones, curved internals and non parallel surfaces inhibit standing waves and cabinet resonances which is always a good thing. Curved baffles and baffle edges limit diffraction and soften the effects of baffle step http://www.southampton.ac.uk/~apm3/diyaudio/Diffra... snd doing this is almost always a good thing. In your case changing the baffle geometry might not be such a good idea though; if the sound of your current speakers is just right for you then I would try to keep the baffle dimensions and shape very similar to what you have now. The reason being that making big changes is going to change the dispersion of the speaker ( Polar response ).
If your doing your own then you might as well do something special on the inside....something like this maybe ?
http://www.pbnaudio.com/speakers/innerchoic/sammy-...
You'll have noticed many commercial speakers using curved cabinets, spherical mid enclosures, radiussed edges etc etc and you now have the opportunity to do this with your new enclosures.Curved shapes are stronger than straight ones, curved internals and non parallel surfaces inhibit standing waves and cabinet resonances which is always a good thing. Curved baffles and baffle edges limit diffraction and soften the effects of baffle step http://www.southampton.ac.uk/~apm3/diyaudio/Diffra... snd doing this is almost always a good thing. In your case changing the baffle geometry might not be such a good idea though; if the sound of your current speakers is just right for you then I would try to keep the baffle dimensions and shape very similar to what you have now. The reason being that making big changes is going to change the dispersion of the speaker ( Polar response ).
If your doing your own then you might as well do something special on the inside....something like this maybe ?
http://www.pbnaudio.com/speakers/innerchoic/sammy-...
You can buy decent drive units from Wilmslow Audio - perhaps that's where you bought yours from?
There are a few decent free (and some low cost) speaker design programs out there - although you need to know the drive unit parameters (bass unit in particular) - which can get quite technical.
You essentially match the drive unit to the cabinet, and the parameters of the drive unit also determine whether the cabinet is to be a sealed unit or ported.
To be honest, there are some damn good baragins out there right now - you could simply get a pair of Wharfedale 9.1, which have a nice curved cabinet too, for £100 or less, and they are really, really good little speakers for the money.
Of course, if you want the pleasure of building your own - then please don't let me put you off!
ETA: Corrected spelling error.
There are a few decent free (and some low cost) speaker design programs out there - although you need to know the drive unit parameters (bass unit in particular) - which can get quite technical.
You essentially match the drive unit to the cabinet, and the parameters of the drive unit also determine whether the cabinet is to be a sealed unit or ported.
To be honest, there are some damn good baragins out there right now - you could simply get a pair of Wharfedale 9.1, which have a nice curved cabinet too, for £100 or less, and they are really, really good little speakers for the money.
Of course, if you want the pleasure of building your own - then please don't let me put you off!
ETA: Corrected spelling error.
Edited by TonyRPH on Friday 12th April 22:41
TonyRPH said:
To be honest, there are some damn good baragins out there right now - you could simply get a pair of Wharfedale 9.1, which have a nice curved cabinet too, for £100 or less, and they are really, really good little speakers for the money.
Of course, if you want the pleasure of building your own - then please don't let me put you off!
To be honest, part of the reason i want to build my own is because i want something unique. Of course, if you want the pleasure of building your own - then please don't let me put you off!
I know there are bargains to be had out there, but i went to a lot of demonstrations when my dad was upgrading his system and the only bookshelf speakers that i was genuinely impressed with were the MA Gold series, which are pretty expensive and i was left underwhelmed by many others, including the Dali Ikons. Maybe i just like the way they sound, but i think i will struggle to find a bookshelf speaker i prefer without spending a long time and a lot of money.
It also, to me, seems like a crime disposing of speakers which are truly excellent, when they can be improved and renewed for a couple of hours of work
I don't exactly know how old the speakers are. I know my dad bought them for my grandparents, i think when my grandfather was still alive, so it would be at least 24 years ago. To me, it comes as a surprise how little speakers have improved for a reasonable budget, i guess it all comes down to opinion when you start looking at £5k+ for a pair of speakers....
slomax said:
It also, to me, seems like a crime disposing of speakers which are truly excellent, when they can be improved and renewed for a couple of hours of work
I couldn't agree more.slomax said:
I don't exactly know how old the speakers are. I know my dad bought them for my grandparents, i think when my grandfather was still alive, so it would be at least 24 years ago. To me, it comes as a surprise how little speakers have improved for a reasonable budget, i guess it all comes down to opinion when you start looking at £5k+ for a pair of speakers....
Cabinet and drive unit design has improved a fair bit with computer optimisation.However, with some speaker models, the designers just got it right back in the day, usually by good calculations, and then further optimisation by trial and error / listening tests.
It's these same models that are fairly sought after these days.
I remember reading an article about modern speaker design, and the engineers can essentially create a specific sound with the use of a computer now.
Good luck with building your cabinets - sadly cabinet manufacture was never one of my strong points, despite my dad being a cabinet maker - I just didn't learn his skill.
This site has useful information and calculators for anyone wanting to learn a little more about speaker design. http://www.mh-audio.nl/spk_calc.asp
Terminals, ports, damping material etc can be found here.
http://www.falconacoustics.co.uk/
http://www.wilmslow-audio.co.uk/
http://www.iplacoustics.co.uk/
http://www.audio-components.co.uk/
http://www.qtasystems.co.uk/loudspeaker-components...
The following sites have some very well developed designs if you get into building your own. Imho Troels Gravesen's understanding of crossover design is up there with the better commercial designers. Tony Gee's Humble Homemade Hi-Fi site also has some great 'cloned' designs using well thought out cabinetry.
http://www.troelsgravesen.dk/Diy_Loudspeaker_Proje...
http://www.humblehomemadehifi.com/download.html
Terminals, ports, damping material etc can be found here.
http://www.falconacoustics.co.uk/
http://www.wilmslow-audio.co.uk/
http://www.iplacoustics.co.uk/
http://www.audio-components.co.uk/
http://www.qtasystems.co.uk/loudspeaker-components...
The following sites have some very well developed designs if you get into building your own. Imho Troels Gravesen's understanding of crossover design is up there with the better commercial designers. Tony Gee's Humble Homemade Hi-Fi site also has some great 'cloned' designs using well thought out cabinetry.
http://www.troelsgravesen.dk/Diy_Loudspeaker_Proje...
http://www.humblehomemadehifi.com/download.html
Edited by Crackie on Friday 12th April 23:37
Hi Crackie,
Thanks for all the info!
I don't want to start off my first proper project toying with components/electrics too much, but i will keep those sources in my favourites in case i get into it more, its certainly a possibility!
From what i gather, skim reading it for now, the most important features are the port size/position and proximity, and the internal volume.
When i get chance i will have a proper read over the links, something like those Sammy speakers internally is entirely feasible with the construction/tools i have in mind/available to use.
some others i have seen are these:
which look pretty cool...
Thanks for all the info!
I don't want to start off my first proper project toying with components/electrics too much, but i will keep those sources in my favourites in case i get into it more, its certainly a possibility!
From what i gather, skim reading it for now, the most important features are the port size/position and proximity, and the internal volume.
When i get chance i will have a proper read over the links, something like those Sammy speakers internally is entirely feasible with the construction/tools i have in mind/available to use.
some others i have seen are these:
which look pretty cool...
TonyRPH said:
I remember reading an article about modern speaker design, and the engineers can essentially create a specific sound with the use of a computer now.
In my experience the better modelling, baffle diffraction and FEA programs generate extremely accurate predictions of a systems final measured performance.
http://www.ijdata.com/LspCAD_optimizer.html usually gets to within a db in the bass when loaded with accurate TSP data.
http://www.tolvan.com/edge/help.htm is useful higher up.
slomax said:
Hi Crackie,
Thanks for all the info!
I don't want to start off my first proper project toying with components/electrics too much, but i will keep those sources in my favourites in case i get into it more, its certainly a possibility!
From what i gather, skim reading it for now, the most important features are the port size/position and proximity, and the internal volume.
When i get chance i will have a proper read over the links, something like those Sammy speakers internally is entirely feasible with the construction/tools i have in mind/available to use.
some others i have seen are these:
which look pretty cool...
Hi Slomax - I like those.........Thanks for all the info!
I don't want to start off my first proper project toying with components/electrics too much, but i will keep those sources in my favourites in case i get into it more, its certainly a possibility!
From what i gather, skim reading it for now, the most important features are the port size/position and proximity, and the internal volume.
When i get chance i will have a proper read over the links, something like those Sammy speakers internally is entirely feasible with the construction/tools i have in mind/available to use.
some others i have seen are these:
which look pretty cool...
Best of luck with the cabinets, hope they turn out the way you want.
cheers!
I have massive amounts of uni work up until my degree show during the first week of June, so after that i will have until the end of June to make use of workshops. I also have access to a milling machine.
When i get some time i will pen some ideas/shapes and make some 3D models/renders/exploded diagrams and keep the thread updated.
All input will be welcomed into the design/alterations.
I will also probably make a section on my website (www.niallmcloughlin.co.uk) when i get chance/time to do so.
I have massive amounts of uni work up until my degree show during the first week of June, so after that i will have until the end of June to make use of workshops. I also have access to a milling machine.
When i get some time i will pen some ideas/shapes and make some 3D models/renders/exploded diagrams and keep the thread updated.
All input will be welcomed into the design/alterations.
I will also probably make a section on my website (www.niallmcloughlin.co.uk) when i get chance/time to do so.
Have a look at the assembly method used for the Magico Mini 2 http://www.soundbysinger.com/manf.php?doc_id=232. Laminated ply as you mentioned in your earlier posts, stiffening bracers in some of the laminations, holes running top to bottom which are used to clamp the whole structure together. Add in the irregular internal surfaces you saw in the PBN Sammy and you should have something special. It would be sensible to carefully develop the shape of the internal bracer(s) in the position behind the bass driver so you can mechanically 'ground' the back of the magnet 
.
. Crackie said:
Have a look at the assembly method used for the Magico Mini 2 http://www.soundbysinger.com/manf.php?doc_id=232. Laminated ply as you mentioned in your earlier posts, stiffening bracers in some of the laminations, holes running top to bottom which are used to clamp the whole structure together. Add in the irregular internal surfaces you saw in the PBN Sammy and you should have something special.
i had all of those features on my mental tick list
can you explain what you mean by
Crackie said:
It would be sensible to carefully develop the shape of the internal bracer(s) in the position behind the bass driver so you can mechanically 'ground' the back of the magnet.
Im really excited for this project now! slomax said:
can you explain what you mean by
The magnets on the bass/mid drivers are relatively heavy and their mass isn't well supported inside the cabinet ( cantilever effect ). The shape of the bracers inside the cabinet can be designed so that, when the driver is screwed into the baffle, the magnet is also pushed against the internal bracers. Try to aim for the center line of the bracer being on the center line of the magnet. If the bracer is machined to be a couple of mill clear of the magnet then a suitable damping rubber can be clamped between the two. This will help strengthen the whole structure and also limit resonances in the magnet/driver assembly. Crackie said:
It would be sensible to carefully develop the shape of the internal bracer(s) in the position behind the bass driver so you can mechanically 'ground' the back of the magnet.
Im really excited for this project now! Crackie said:
The magnets on the bass/mid drivers are relatively heavy and their mass isn't well supported inside the cabinet ( cantilever effect ). The shape of the bracers inside the cabinet can be designed so that, when the driver is screwed into the baffle, the magnet is also pushed against the internal bracers. Try to aim for the center line of the bracer being on the center line of the magnet. If the bracer is machined to be a couple of mill clear of the magnet then a suitable damping rubber can be clamped between the two. This will help strengthen the whole structure and also limit resonances in the magnet/driver assembly.
AHA!!I completely understand what you mean now! thought it was going to be a bunch of complex physics incorporating reflections and angles of sine waves etc
Good idea!
shouldnt be difficult to do if i slice a 3D model for manufacture
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