As mentioned before, we are going to add an external Hi-Pass filter that will sit in front of the poweramp driving mid/high section (that will have a passive low pass for mid, and high pass for high, with relatively small/less expensive components)
Why go to this elaborate external filter?
As I am now going full monty in CNC work I designed an enclosure out of a single milled piece of aluminium;
The layout is in full progress, but will need a few weekends to finish.
Why go to this elaborate external filter?
- It removes the need for an expensive large (300µF) capacitor in front of the 2.8 Ohm midrange
- It removes an LCR correction circuit that would remove the 80Hz resonance peak of the midrange
- It will make tweaking much easier as this filter wil have an adjustable 6, 12, 18 or 24 dB/oct slope (like the DSP in front of LF with Hypex)
- It will have a frequency adjustment from 100 to 1400 Hz in 50 steps
- It will also have a buffered LF output with 15 steps of attenuation in exact 1dB increments.
As I am now going full monty in CNC work I designed an enclosure out of a single milled piece of aluminium;
The layout is in full progress, but will need a few weekends to finish.
I am not sure I understand what you try to tell me grindstone. But I expect that when we are done we will have a very sturdy enclosure. The 10 threaded steel bars will help kill the last bit of flex and resonance
Sorry for confusion. During machining, if the removal is very aggressive, residual stresses in the base stock material may result in dimensional deviation. I do not know how thin those walls are, but if they are thin, they may not end-up where the toolpath cut them to be, etc. Just a cautionary tale from experience. Looks like it will be a great project, though, thanks for posting and good luck.
Ahhh. I am not sure, but definitely not worried.
The rear is 20mm thick material with 2 larger holes but still quite rigid.
The front starts with 40mm and indeed get's some real large holes and maybe some deformation.
But the front and back are clamped with the MDF/HDF structure in the middle and some sort of a constrained layer damping as between front and enclosure sits a 1,2mm "rubber" EPDM layer, and between enclosure and back side.
Any dimensional deformation is prevented in the way the billet is clamped during machining.
This week they should be done, and I am very curious to the end result.
Stay tuned.
The rear is 20mm thick material with 2 larger holes but still quite rigid.
The front starts with 40mm and indeed get's some real large holes and maybe some deformation.
But the front and back are clamped with the MDF/HDF structure in the middle and some sort of a constrained layer damping as between front and enclosure sits a 1,2mm "rubber" EPDM layer, and between enclosure and back side.
Any dimensional deformation is prevented in the way the billet is clamped during machining.
This week they should be done, and I am very curious to the end result.
Stay tuned.
Here a few pictures of the front and back that came from the CNC.
The front panels had to go back as the space between the units and the aluminium was slightly too little and I was worried the units wouldn't go in well enough when the letherette was applied to the the front.
In the previous design i had the same problem making removing a driver very hard.
There is no reason that the margin is a big wider here.
The front panels had to go back as the space between the units and the aluminium was slightly too little and I was worried the units wouldn't go in well enough when the letherette was applied to the the front.
In the previous design i had the same problem making removing a driver very hard.
There is no reason that the margin is a big wider here.
On one side this is an impressive build, great details and nice ideas (better steal a good idea than develop a bad one by your self).
On the other hand, if my green finger lifts up, what a ridiculous waste of material and energy. I hope you will use it longer than your TESLA battery car.
You sure will not get an A mark from the "last Generation" for it. So don't be surprised to find a buch of kid's glued to your speakers one day...
If you still worry about the 10 bolts you use to fix the baffle, simply putting a shrink tubing on the threads is damping their resonances quite well.
On the other hand, if my green finger lifts up, what a ridiculous waste of material and energy. I hope you will use it longer than your TESLA battery car.
You sure will not get an A mark from the "last Generation" for it. So don't be surprised to find a buch of kid's glued to your speakers one day...
If you still worry about the 10 bolts you use to fix the baffle, simply putting a shrink tubing on the threads is damping their resonances quite well.
Thanks Turbowatch2
To be honest I did not at all think about the energy it costs to mill the front and back (just the cost €€)
I do think that the energy used (about 8 hours per speaker set) is less than flying a 300kg Magico or Wilson from the US to Europe.
With respect to waste of material, all removed aluminium will be recycled.
To me the heavier the speaker the better it sounds, and this curve can be noticed to well in the 100kg weight, above that I guess the effect drops.
??? How did you know I drive a Tesla .....actually my second 😉 (and last) I can't remember I mentioned that anywhere.
And after 7 years my old speaker will get a new home for many years to come, and indeed I guess way longer than my Tesla.
The shrink tubing is indeed part of the plan, but also press some rubber between the rods and the side panels.
The 6 rods that run trough the midrange compartment will actually be partly damped automatically as they pass a panel half way.
Cheers,
Peter
To be honest I did not at all think about the energy it costs to mill the front and back (just the cost €€)
I do think that the energy used (about 8 hours per speaker set) is less than flying a 300kg Magico or Wilson from the US to Europe.
With respect to waste of material, all removed aluminium will be recycled.
To me the heavier the speaker the better it sounds, and this curve can be noticed to well in the 100kg weight, above that I guess the effect drops.
??? How did you know I drive a Tesla .....actually my second 😉 (and last) I can't remember I mentioned that anywhere.
And after 7 years my old speaker will get a new home for many years to come, and indeed I guess way longer than my Tesla.
The shrink tubing is indeed part of the plan, but also press some rubber between the rods and the side panels.
The 6 rods that run trough the midrange compartment will actually be partly damped automatically as they pass a panel half way.
Cheers,
Peter
I may play devils advocate for a second. If you had used some kind of wood based particle or fiber board and integrated some concrete slabs and or sand filled cavity in the build, you would have had the same or even a better effect. There is nothing that qualifies aluminum for speaker building but the owners Ego. With amps you can point to the great heat dissipation, but cases cut from a massive chunk of aluminum are not the future of the world.
Compared to an electric car, that will be scraped after a few years with no working recycling in sight or even wanted by Elon, your build is quite "Green" of course. It is just not the way we all should build our speakers. All talk, no consequence? I may add a picture if you don't mind.
I'm just building a subwoofer that eliminates 100% of mass impulses in a very simple and consequent way by two opposing drivers. Guess what it is build from? The doors of a more than 55 years old wall unit (or Wandmeubel) and some cut off pieces of wood from the ijzerhandel's 1 Euro box.
The veneer is rose wood palisander or Cocobolo from a time no one cared about any rainforest.
Also, not the way for anyone, but a stark contrast in energy consumption and use of resources.
Did you know that the Netherlands will be under water decades before Germany? So I do a little compensation for you. on a very small scale...😉
Compared to an electric car, that will be scraped after a few years with no working recycling in sight or even wanted by Elon, your build is quite "Green" of course. It is just not the way we all should build our speakers. All talk, no consequence? I may add a picture if you don't mind.
I'm just building a subwoofer that eliminates 100% of mass impulses in a very simple and consequent way by two opposing drivers. Guess what it is build from? The doors of a more than 55 years old wall unit (or Wandmeubel) and some cut off pieces of wood from the ijzerhandel's 1 Euro box.
The veneer is rose wood palisander or Cocobolo from a time no one cared about any rainforest.
Also, not the way for anyone, but a stark contrast in energy consumption and use of resources.
Did you know that the Netherlands will be under water decades before Germany? So I do a little compensation for you. on a very small scale...😉
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The consumption of resources and environmental impact of @PSchut 's speaker is an insignificant tiny miniscule micro-drop in the vast ocean of human activity. Talking about it is completely irrelevant to this thread.
I would agree with hifijm, and the choice of material is a careful consideration of compromises, as in the end it is all about compromises.
@ Turbowatch2. That is a serious enclosure. Dual 15"? The two opposite woofers will cancel out moving mass vibrations. I used for many years an Audio Physic Minos subwoofer (fantastic unit) that uses 2 opposite 12" Peerless woofers but I sold it this year as it just didn't fit the living room anymore and is now replaced by a smaller Dynaudio S18 (with opposite firing woofers as that is the best way to make a sub). It is only used for surround/Atmos movies and can keep up quite well and used below 38Hz
I would increase the internal bracing on your sub as the panels seem quite large, and although you cancel out vibrations induced by the cone mass, you will get vibrations induced by modulated pressure. I would use bracing not further separated than 10/15 cm.
- The first goal was they need to be smaller in all dimensions than the current one (current speaker that is sold)
- Then I would like to try to equal or improve on its sonic performance, and I would be happy if it is equal.
- To achieve that I need mass, filling cavities with sand or concrete will jeopardize goal 1 (and has less mass than aluminium). One of the first HiFi speakers I build was a design by "Elektuur" magazine using KEF units and sand filled side panels. Heavy, but not the best size/weight ratio and they didn't sound that good either.
- Simulation told me that the tweeter needed to be slightly backwards so a curved baffle was the solution
- I ended up with the midrange under 3,3 degrees to avoid irregularities, so the front panel was getting more complex. This forced me to use a 5-axis CNC machine and I needed to deliver that in a .STEP file, and that meant I needed to learn Fusion 360 (a nice holiday task last June)
- The front horizontal curve is using the golden ratio to get a near perfect radiation pattern with as little as possible diffraction of the edges
- I considered 2 woofers in opposite direction on the sides but it made the front wider than I wanted, and yes, I think it is THE best way for a subwoofer but only if you don't go higher than 80Hz, above that there will be phase problems and although I would like to cross as low as possible to midrange tweaking can move it up to the 300Hz region as that is the theoretical lowest frequency the midrange will go because of the baffle-step attenuation then again the filter curves will influence this.
@ Turbowatch2. That is a serious enclosure. Dual 15"? The two opposite woofers will cancel out moving mass vibrations. I used for many years an Audio Physic Minos subwoofer (fantastic unit) that uses 2 opposite 12" Peerless woofers but I sold it this year as it just didn't fit the living room anymore and is now replaced by a smaller Dynaudio S18 (with opposite firing woofers as that is the best way to make a sub). It is only used for surround/Atmos movies and can keep up quite well and used below 38Hz
I would increase the internal bracing on your sub as the panels seem quite large, and although you cancel out vibrations induced by the cone mass, you will get vibrations induced by modulated pressure. I would use bracing not further separated than 10/15 cm.
Turbowatches Dutch isn’t that bad for someone residing in Germany…
I won’t question the build, rather envy the thoroughness and expense 🤐, however the techniques to minimize sound transmission through solid material are pretty well established. Weight helps, but stiffness and lack of damping isn’t an advantage. Moreover, I think excessive attention to this design aspect really isn’t needed, it’s not exactly the weakest link once a basic level has been reached. Of course it feels good and that is legit in itself. But I think Celestion used aluminum a lot smarter decades ago.
I won’t question the build, rather envy the thoroughness and expense 🤐, however the techniques to minimize sound transmission through solid material are pretty well established. Weight helps, but stiffness and lack of damping isn’t an advantage. Moreover, I think excessive attention to this design aspect really isn’t needed, it’s not exactly the weakest link once a basic level has been reached. Of course it feels good and that is legit in itself. But I think Celestion used aluminum a lot smarter decades ago.
That's why the Dutch are already adapting genetically in advance and are the tallest nation on earth.
And sorry to @PSchut and the dutch - no offence intended! By the way, recent dutch building code defines 2,30 m minimum heigth for (main) doors, while for most other countries it's still around 2 m.
@PSchut I really like your build (s), I think you got that. You build some awsome looking speakers (the last and this one) with incredible thought of detail, not to mention the financial effort. You sure spend more money in the CNC shop than most people on HIFI gear in a whole life..
It is just that I become a little thoughtful about the amount of material used while searching for the optimum. There may be alternatives which are less massive for the future.
In contrast to your build, the majority of commercial builds is a complete waste of precious material. Just look at all these cheap, Asian made HIFI and HT speakers you find at retail centers. Not even to mention all that BOSE, Logitec etc. plastich junk, which will last the warranty period plus a few days. The curse of commerce.
There should be a way between such extremes.
Nice you asked about my sub. I didn't want to hijack your thread, just use it as an example for low cost. In fact it was build from materials already in my house. As I metioned, the verneered panels and massive edges were old cabinet doors. My parents bought them when I was 8 years old and had them rebuild and extended in two other houses. It is looking larger than it is, because it is pictured while getting (hand) painted with the beam inside, which makes it easy to rotate. It only is 2x36 liter net volume, 67x43x40cm and will get two 10" driver. Should be an f3 of 25 Hz. The particle board is 20mm strong. You are right with the bracing, I usualy preach exactly as you mention,10-15cm squares and this one is on the wide side. I verify the result by knocking on the outside. There are a few areas inside this build that could need more braces, but I choose to glue 2.5mm aluminum/ butyl on these audible resonating surfaces, to keep clear of the driver. Alubuthyl, in combination, works very good. Anyway, compared to expensive commercial subs, this one is just sounding dead as Dodo. With the cones 60cm apart, you still get an acoustic in room result near to +6dB optimum compared to one driver, one amp. It will run up to 80 Hz.
It is just that I become a little thoughtful about the amount of material used while searching for the optimum. There may be alternatives which are less massive for the future.
In contrast to your build, the majority of commercial builds is a complete waste of precious material. Just look at all these cheap, Asian made HIFI and HT speakers you find at retail centers. Not even to mention all that BOSE, Logitec etc. plastich junk, which will last the warranty period plus a few days. The curse of commerce.
There should be a way between such extremes.
Nice you asked about my sub. I didn't want to hijack your thread, just use it as an example for low cost. In fact it was build from materials already in my house. As I metioned, the verneered panels and massive edges were old cabinet doors. My parents bought them when I was 8 years old and had them rebuild and extended in two other houses. It is looking larger than it is, because it is pictured while getting (hand) painted with the beam inside, which makes it easy to rotate. It only is 2x36 liter net volume, 67x43x40cm and will get two 10" driver. Should be an f3 of 25 Hz. The particle board is 20mm strong. You are right with the bracing, I usualy preach exactly as you mention,10-15cm squares and this one is on the wide side. I verify the result by knocking on the outside. There are a few areas inside this build that could need more braces, but I choose to glue 2.5mm aluminum/ butyl on these audible resonating surfaces, to keep clear of the driver. Alubuthyl, in combination, works very good. Anyway, compared to expensive commercial subs, this one is just sounding dead as Dodo. With the cones 60cm apart, you still get an acoustic in room result near to +6dB optimum compared to one driver, one amp. It will run up to 80 Hz.
Oh ... and I live in Tilburg with a 10 meter increase in sea level we will just keep our feet dry.
Why polymer materials as Wilson Audio or Geddes loudspeakers is not used for the walls of the cabinet in spite of not ruled hazardous wood assemblies (glue, difficulty of good made bracing and flew of the wood box, etc)? They seem more quiet than the fulll alumin Magicos.
It could makes sense as a lot of engineery effort are made on the cabinet side and the complexity seems well handed by your ressources, knowlledge and skill on that structure side of our hobby.
It could makes sense as a lot of engineery effort are made on the cabinet side and the complexity seems well handed by your ressources, knowlledge and skill on that structure side of our hobby.
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I just like woodworking and the sides needed to be real wood to fit the interior of our living room. Trespa is considered by my co builder as he wants a white speaker, and that also adds some serious mass
