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Metal speaker baffles worth it?


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#1 AbdulC

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Posted 28 May 2018 - 23:02

Hi guys

Currently my elates are mounted in my e class doors using mdf baffles and tbh they're fine BUT I'm planning on redoing the baffles and grills soon as currently they're off axis and I'd like to bring them out on axis a little more without it being too obvious to aid with the upper end frequency response.

Anyway, I've seen people using metal speaker baffles (steel, alloy?) and im just wondering if it's worth going this route over treated mdf or birch ply? The aim here would be to maximise my midbass output which is btw bloody impressive if I do say so myself but ultimately the only way I can improve the midbass output now is to either go for bigger drivers or improve the installation I've got and frankly bigger drivers aint happening.

In case anyone is wondering doors have had inner and outer skins treated with 4mm silent coat to the tune of 90% coverage I'd say with all holes sealed then a layer of silent coat isolator 6 on top... not sure i can really do anything more there. The midbass were run off a bridged Genesis P4U but I'm changing over to a HD600/4 which will again be bridged for maximum effect lol.

Thanks all
Abdul

Ps how are people making angled rings/baffles to build the midbass baffles out or am I best off with regular speaker rings and some sort of fibreglass filler or bridging compound?

Edited by AbdulC, 28 May 2018 - 23:02.


#2 bigrigbri

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Posted 29 May 2018 - 10:44

The benefit of using steel as a spacer/damping ring is the weight density per area to kill resonance.
Aluminium rings are not a good idea for midbass as it is a third of the weight of steel and it's the weight/density that's needed.
The mdf rings you have I see work fine but will over time soak up the moisture and puff up rendering them US.
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#3 Mannparry

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Posted 29 May 2018 - 10:53

They’ll also allow the speakers to breathe easier. 


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#4 bigrigbri

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Posted 29 May 2018 - 14:36

How.
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#5 Mannparry

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Posted 29 May 2018 - 14:43

5mm baffle vs 10-12mm baffle. 


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#6 puggie

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Posted 29 May 2018 - 14:47

I'll buck the trend and say I think that steel rings are a bit of a compromise:

 

They do allow you to make a nice solid dense baffle that is easy to mount speakers to solidly and fit to your door. these are all really good things

 

But

 

I (currently, i'm a fickle chap) prefer Trespa for making baffles, its a very high density plastic used for cladding buildings and (where I work) chemical resistant lab bench tops where you need them to be very strong (we use them for radiation setups where you might have 400kg of lead brick on there). It is designed to be worked with std wood working tools, so your jig saw and router are perfectly good for working it, it cuts like a very hard wood without any knots or imperfections. it will tap threads extremely well (or take self tapping fixings with a pilot hole), and they are strong, I have broken the heads off M4 bolts threaded into trespa with no damage to the thread, and being a plastic they have a degree of self locking, fixing do not work loose in there. Steel is a very resonant material, its no good for damping, it will just lower the resonant frequency of your current mount, trespa will actually dampen a metal door as it is not resonant as steel. If you want to add mass and dampen, lead is a much better deadener being both very heavy/dense and flexible/non resonant.

 

Also be very careful of making a tube to mount your drivers in,you will get resonant issues at certain frequencies, I have seen people cut a piece of thick wall steel tube at an angle and use that as a space, this is not ideal from a resonance point of view, but again is quick and easy, and will improve a lot of areas (more solid mount, angle to get the driver on axis etc) but probably cause a hollow resonance issues that you didn;t have before, longer the tube the more pronounced it will be.

 

Steel baffles are often seen as the best option by many but i think if you are going all out there are better materials to do the mounting, mass adding and deadening you want from you speaker mounts. it requires more thought and a range of materials rather than one solution solver most of it... sort of.


5mm baffle vs 10-12mm baffle. 

 

I'd rather run a 12mm chamfered baffle in treated birch ply or Trespa than a 5mm steel baffle, to be honest a 5mm baffle I would be looking to chamfer so you have little to gain making is to thin as it would become resonant. IMHO.


It's an ageing estate car with a bonkers super car engine, known for being fragile.

What do you mean it's not a sensible family car and could be a potential money pit?!?!

#7 bigrigbri

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Posted 29 May 2018 - 16:51

That Trespass looks great for making things out of.
I wouldn't use 5mm thick steel for a ring.
Possibly for a bracket to hold a pen.
12mm or thicker and with some silent coat on will deaden any real life remaining vibes.
A further ring on the inside of the door bolted through will add further with a larger bore to counteract the port effect as Puggie suggests.
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#8 puggie

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Posted 29 May 2018 - 17:27

Tufnol or the attwater equivalent on ebay is also quite nice material for baffles, not as nice to work, it's a phenolic bonded cotton material, I primarily use if for making high voltage power distribution panels, but that would be worth looking at for baffles. I'm planning on a resin or 2 part silicone and fine blasting garnet for local used mass and deadening.
It's an ageing estate car with a bonkers super car engine, known for being fragile.

What do you mean it's not a sensible family car and could be a potential money pit?!?!

#9 Go2

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Posted 29 May 2018 - 17:39

waste of time and effort, it's a car. stick with mdf and a lick of water proof paint.



#10 AbdulC

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Posted 29 May 2018 - 21:41

Holy Molly in typical TA fashion one thing leads to another...

Need to get to reading about this Trespa stuff. Puggie where could I source some?

Current baffles are 38mm in depth, the rings I was going to add on to bring the speakers a little more on axis are 16mm on one side and 2mm on the other I believe so shouldn't make a huge difference unless I double up. At what point do I need to start thinking about this tunnel effect having negative impact on sound? And sorry for the sq newb questions but what does it sound like? Like an echo or something?

I've been reading lots of interesting threads on here and see the terms coloration and cone break up mentioned, what do these terms mean?

I've also been considering moving onto 8-9" midbass drivers but i dont think it'll be possible as ill need to pile up the rings to get the clearance needed. No amount of chamfer will save me there lol.


Many thanks guys
Ps what is beaming? Lol

#11 Mannparry

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Posted 29 May 2018 - 22:17

Are you 2 way or 3 way?


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#12 AbdulC

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Posted 29 May 2018 - 23:01

2 way... mt23s and elate 6.5s

#13 puggie

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Posted 30 May 2018 - 07:46

Trespa, my stash is from skip diving at work when we refurbish labs. But I reckon someone will sell off cuts through ebay or similar. Corian the artificial marble/granite that they make worktops from might also be worth a look, some kitchen fitter must have a stack of off cuts from sink cutouts and short ends.

Colouration is basically a distortion.

The tunnel effect is going to be a kind of peak resonance to the sound. You are making a ported enclosure with the door as the enclosure and the tunnel as the port. The relative size of each will dictate the frequency and severity of the resonance.

Cone breakup is essentially the rigid structure of the cone breaking up into resonant modes. You drive a speaker from the voice cool in the middle. Eventually when the movement becomes fast enough (from volume or frequency played) the cone will flex, you will get a point where the outside edge of the cone cannot keep up with the motion of the voice coil in the middle. This will start be making the driven cone appear smaller as only the centre is keeping up (kind of a good thing) but the outer edge is now playing out of time/phase which creates distortion (not a good thing). Some materials do this in a much nicer way than others, poly cone drivers (I think your elates are) have well damped cones where the outer uncontrolled portion is well damped, metal cones are terrible for this, massive peaks usually appear at higher frequencies meaning you really need to use high order crossovers, Paper cone are usually a happy medium.

Beaming. Once the half wavelength of you frequency played is shorter (higher frequency = shorter wavelength) than diameter of the moving part of your speaker cone, then the sound output becomes more directional and on axis to the driver. A 6.5" speaker typically has a 4.5" cone once you lose the frame and surround. This give a frequency of about 1.5khz. In practice your cone break up will make the cone seem smaller and the beaming may start higher up.
It's an ageing estate car with a bonkers super car engine, known for being fragile.

What do you mean it's not a sensible family car and could be a potential money pit?!?!

#14 Gamma_ed

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Posted 01 Jun 2018 - 07:50

I have used it all for my elates, steel, mdf wood, alluminium. 

 

But steel is nice for the weight, don't make it too high, otherwise the speaker can not breath, and then it sounds like a hollow pipe to listen to.