BroadBand Bass Trap's Build

**Lonely Raven** · **02-22-09, 11:03 PM**

Quote:

cinema mad wrote:

The bearings should'nt be tight at all and can lead to issues, It sounds like the Rotor (armature) was poling (rubbing on the stator)... The little Slip ring on the front of the Rotor is only used for Start up it basiclly Engages & disengages the start cap for higher start-up torque it works on centrifugal force, once the motor is spinning at A certain RPM the slip ring disengages the start cap...

Cheers Lonely Raven...

Thanks for that education. I'll be shopping for a used motor and I'll chime in when I get my diffusers done.

**cinema mad** · **02-23-09, 07:48 AM**

If you can, See If you can fined an induction motor with higher hp rating than the original motor but runs around the same RPM as the old motor, "the RPM is the important thing to remember", also the shaft & Key way OD That way you can just swap the pully's straight over and your good to go....

Cheers...

**Lonely Raven** · **02-23-09, 08:25 AM**

I was poking around, and all the induction motors seem to be direct drive setups. Which just isn't possible with this particular saw. All the cap-start, belt drive motors that fit this table are 1HP, 3450RPM with the same pully diameter and shaft setup...which at least makes it easy to swap out another motor.

**Lonely Raven** · **02-26-09, 01:28 AM**

OK, I'm back on track to trying to get caught up with you! I picked up a replacement saw tonight!

And yes, it happens to be the same 25 year old one as mine! LOL

Mine was more tricked out, so I swapped the motor into my old saw which has a cast iron top and better fence. And I got to work!

I'm *really* shocked as to how much this wood warped since Sunday when my saw died! Because I didn't get the relief cuts done before the saw died, it was starting to bow and twist a bit...so my cuts were off quite a bit on some passes because the wood was no longer square. It doesn't help that it was already checked and chipped from being in storage for 13 years....so dont' pick on me for the veins being off!

OK, it's way past my bedtime...I need to be up for work in 5 hours.

Mad, do you have any tips on how I should stain and clearcoat these? I have some nice oil based stain I plan on using...but I'm wondering if I only clearcoat the front side, will that cause it to warp badly because the backside is untreated?

**cinema mad** · **02-26-09, 05:11 AM**

Wow Raven you have been working very hard by the looks of it

, I am impressed.. your not mucking about gettin straight back into it LoL... Good to see you have your table saw up and running...

Yes those cuts in the back are very important to relieve the tension out of the wood & stop the Diffusors warping....

As far as staining I would say just stain the fronts and sides thats all I did & I have'nt noticed any warping, I used A little artist brush to get down into the Diffusion Wells and then used A piece of cotton sheet to quickly rub off the excess to get A nice even stain...

Before Staining I spent A while sanding the diffusors first especially in the Wells, I started with 120grit then 240grit then 420grit to get A nice smooth finnish....

For the clear coats I made sure the Diffusors were free of dust and just painted on with A brush carfully so as not to get air bubbles, so I only stirred the clear in the tin not shaken..
I poured A little at A time into A cup so I would'nt contaminate the large tin of clear with the stain residue that is left on the paint brush after applying the clear coat....

Is that your Blue Suzuki Motor Bike ? what size is it, I am mad on bikes

....

Cheers....

**Lonely Raven** · **02-26-09, 09:51 AM**

Yeah, my fiance and I have his and her's SV650. Her's is a red one just outside the frame. My motorcycling friends are giving me grief for not having covers on the bikes and getting saw dust on them. LOL We've only been riding for two years now...and honestly, it was her idea. I love to ride, but people are stupid, and I'm so afraid she is going to get hit by some motorist not paying attention!

Anywho, thanks for the info on stain and clear. But I should clarify my question. I'm trying to save a few $$ since I'm on reduced hours at work (replacing this table saw dipped into my savings, but I felt it was a need, not a want). So what I'm wanting to do is clearcoat the front side of the diffusers only. But I'm worried that clearcoating only the front, and leaving the backs open to the elements, will cause the diffusers to bow and warp even more. Should I just go ahead and clear every little bit of exposed wood to seal it from humidity/drying out?

If I can afford some more wood, I'm thinking about making some more of these diffusers, but more artistic. e.g. different woods, and cut up and reguled to form some sort of shape rather than just a wall of wells and veins....maybe in a star like shape or something. I have no idea where I'd put it, but it sure would be a conversation piece! LOL I have a similar idea of making some sort of 3D artwork out of absorber panels for an area that I know needs some absorbing to help keep the room balanced left to right.

I've had these great ideas for a while now, but seeing your fine work has inspired me to get up off my rear and make it happen! Thanks for that!

**kepople** · **02-26-09, 09:58 AM**

These are awesome...
I saw you were using a router before, I might have missed the post, but did you switch to a dado blade in the table saw?

I think I will build some of these for my theater as I have been using absorption everywhere.

Most of the diffusors I see are a lot deeper than these. Have you noticed an improvment?

Kirby

**Lonely Raven** · **02-26-09, 12:58 PM**

Jason, check out this listening room!

http://www.soundscapes.nu/design.html

Now that is someone who's *very* serious about diffusion!

**fredk** · **02-26-09, 05:34 PM**

Thats a very cool link Raven! I wish I had access to his shaper. Those diffusers look really good. I need to take a second look at the chapter on diffusers in the Master Handbook of Acoustics to see if I can apply them in my small room.

**cinema mad** · **02-26-09, 11:01 PM**

Raven That is A awesome room the guy has built, He can obviously see the importance of Diffusion LOL

... I also see that he made some Nested QRDs which are the best Diffusors IMO (Diffusor within A Diffusor Within A Diffussor), they offer BroadBand Diffusion but are by far the most complexed to build....

I like the idea he had of using A spindel moulder cutter to cut the wells its the picture of the 3 saw blades on the shaft, not A cheap tool though, the cheapest one we sell made by JET is A mear $2000au

....

As for sealing the back & sides of the Diffusers from the elements I would use some cheap paint ? I have no doubt that left untreated the Diffusors would/could warp over time..

LoL you are so lucky to have A Mrs that likes bikes I wish mine did...
I have had over 35 bikes from dirt inc KX500/KTM500 to road GSXR 1100 - YZR1000(R1) and so on...
I always tell new riders to ride on the defensive be alert and when behined A car never ride on the blind side of the Driver, think as if the car does'nt know you are there...

With motor Cycle accidents its most always the Driver of the car at fault and not the Bike rider no?...

Cheers...

**fredk** · **02-27-09, 10:52 PM**

Drivers fault, rider suffers. Thats why I never owned a bike.

I guy I went to highschool with was good enough to play pro ball until he tangled with a truck with no tail lights, no signal lights and improperl rear view mirrors.

He broke his leg in 3 places as well as his hip.

**Lonely Raven** · **02-28-09, 10:43 AM**

Thanks...you guys make me want to sell off the bikes and buy a tank.

Can we get back to talking about awesome DIY diffusers?

I'm stuck working a good portion of this weekend, so I'm not sure I'll make any progress on my flutter breakers.

My final though with them, is to alternate them on my back wall with 12" wide absorbers of about the same height. So it would be Ab-Dif-Ab-Dif-Ab-Dif-Ab-Dif-Ab. I have some Black Expocloth ready to try out, but I'm too broke to buy material to frame the Absorbers right now...so I might try just cloth wrapping one first.

**cinema mad** · **02-28-09, 12:06 PM**

Sounds good to me Eric, but as you know every room differs so to be honest the best way would be using software like REW or Acoustisofts RplusD and taking measurments before and after placement to confirm you are placing the Diffusors & Absorbers in the optimum positions for your room.....

Cheers Jas....

**Lonely Raven** · **02-28-09, 01:19 PM**

Quote:

cinema mad wrote:

Sounds good to me Eric, but as you know every room differs so to be honest the best way would be using software like REW or Acoustisofts RplusD and taking measurments before and after placement to confirm you are placing the Diffusors & Absorbers in the optimum positions for your room.....

Cheers Jas....

Yeah, I get that, and I've played with REW. I know I have terrible flutter echo front to back, so this is more of a fun experiment than anything else. Anything I do is better then the crazy echo I have now. Even just speaking from the listening position is frightfull.

I'll have to get off my rear and re-learn REW. It's been 5 months since I fired it up last.

**cinema mad** · **03-01-09, 04:58 AM**

I know I should'nt Eric but Here's my little 6 year old son and his dad (me

) showing off for the Camara....
My Son is slightly Autistic & the little 125cc mini bike has been thereputic in helping boost his confidence...

Back to Diffusors and Absorbtion, For my back wall I have Bass traps for each corner floor to ceiling and A 4" 1240mm x 700mm bass trap mounted in the middle above the rear seats stradaling the rear wall and ceiling, I planed on Building some large BroadBand Nested QRDs using A prime number 11 or 13 sequence to fill the back wall which should give an affect of the room sounding larger than it really is....

Cheers.....

**Lonely Raven** · **03-01-09, 01:02 PM**

That's great, Jason! Anything that gets him interacting with the outside world is fantastic. And that's a great shot that I'm betting you'll cherish years from now as well.

I'm not scared of the motorcycles, really I love them, and I wish I could afford to ride on the track where my only worst enemy would be me! LOL

**cinema mad** · **03-19-09, 06:50 AM**

Well I have A little time on my hands so Have decided to make some Broadband QRD based Abffusors (diffusor absorber in one acoustic panel) ...

I have designed & drawn up my plans, I will be making A prototype first & then pump out A few of these for my back wall and so on...I am going to make the sides of the frame out of 1-1.5mm sheet metal (pre fab to my spec) this time to keep the weight down and give them A total prof manufacture look....

Bradfords Semi Rigid fiberglass 2" Ultratel" with brown kraft paper or thin plastic film will be used for membrane to reject high freq & 3mm plywood to form the veins of the Diffusor...

Specs for abffusor:
-------------------
Diffusion (QRD)
Prime seed = 13
Frequencey = 945hz
Frequency low = 708.8 Hz
Frequency high = 3,448.9 Hz (My flutter Echo diffusors work from 3400hz up
--------------------------------------------------------------------------
Absorbtion: 800-700hz down
NRC=102, 2"ultratel(705) up to 7" thick
-----------------------------------------
The total outside dimentions (OD) will be:
H = 1.2mt (4')
W = 70-75cm (2.4'
D = 17.4cm (7")
-------------------------------------
Colour: Black

Picked up my Ultratel so getting the rest of my stuff tomorrow

more step by step pictures to come
Cheers....

**Lonely Raven** · **03-19-09, 08:26 AM**

Awesome! Sounds like you have it well planned out!

I'm still having trouble trying to fathom how it works, but the kraft paper part makes much more sense now!

I can hardly wait to see them!

**cinema mad** · **03-19-09, 11:27 AM**

Hi Eric, Good to hear from you mate..

Because my time is fairly limited (to many things going on) I will be running around tomorrow to source the parts for the prototype so I can then have A fully assembled/working Abffusor to relay to potential metal fab companys A clear understanding of what I will require them to manufacture/fabricate in regards to the metal frames only....

Cheers.....

**Lonely Raven** · **03-19-09, 11:36 AM**

That part sounds awesome!

I'm working on building up my first router table this weekend. I have the router, fence, and router plate arrived yesterday...I just need to build the table and cabinet!

It seems kinda backwards though, since I should probably be sticking with the table saw for the deeper flutter breakers I hope to build, but I think your way of doing the diffusers on the router is much easier than what I was doing on the table saw!

Looking forward to seeing your projects!

**cinema mad** · **03-19-09, 12:32 PM**

Hi Eric,
Actualy I would think the table saw method would be much faster thus easier to produce the flutter echo tiles, where as the router method would be A lot slower but offer A more precision/ tighter tolerance diffusing well....
So each has trade offs LOL...

Cheers mate...

**Lonely Raven** · **03-19-09, 12:56 PM**

Thanks for those thoughts...that's how I was feeling about it as well.

Good luck on your next build! These are a great inspiration to me, and hopefully to others as well!

**Prof.** · **03-19-09, 06:52 PM**

Quote:

cinema mad wrote:

I am going to make the sides of the frame out of 1-1.5mm sheet metal (pre fab to my spec) this time to keep the weight down and give them A total prof manufacture look...

Jason...Are you just going to use the sheet metal as side edging around the perimeter of the panels, for decoration purposes, or does it serve some other use.?

**cinema mad** · **03-19-09, 10:53 PM**

Hi Prof, Good to hear from you mate..
The Frame of the Abffusors will be fabricated/constructed of 100% 1-1.5mm mild steel sheet to keep the weight down as opposed to 20mm wood, The frame will contain 16 folds total to add to the rigidity and all precession lazer cut.. Also there will be some pattern in the side of the frame to further reduce the weight but not sure what at this stage....

Cheers...

**robbo266317** · **03-19-09, 11:07 PM**

Quote:

cinema mad wrote:

The frame will contain 16 folds total

What are the folds?

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