It worked - it fu**ing worked !!

[junya-eskimo]

Over the last few days, i have been posting here that i will build tuned helmholtz traps..

Well i just put them together. AND IT WORKED..

I knew it was supposed too, but i was sure i was going to mess somthing up along the way..

Dude.. -18DB of the target frequency.. 59 Hrtz..

I just wanted to say i wont bombard the forum with helmholtz post again...ehe..

I just cant believe it.. These traps are all fr friends.. and i was so worried i would mess it up and spend there money..

great day..

Thanx for all help i got from people.

John

I would post pictures but unless you get excited from a box with holes in it, there is not much point..eh

[OttoPus]

-18 dB?? Some details please :O

[Glenn Kuras]

Yes sir if done right they will work. Bryan and I built some (membrane tuned traps) and had them tested at Riverbank and also in our own lab/test room. Have some before and after of the testing?

[Karloff70]

-18db??? F***ing hell.......how big are these things? I have a 120Hz issue, maybe I should consider this 'box with holes in' thing after all......was under the impression unless you paste plenty of it around it won't really do that much......

[Jens Eklund]

Originally Posted by junya-eskimo

I just wanted to say i wont bombard the forum with helmholtz post again...ehe..

Why not? I think a lot of people are interested in knowing more about your success and how to replicate it.

[DanDan]

I would definitely celebrate and would love to see an example of DIY success.
Please do post construction photos and material details.
But abvove all else please do show us how you are measuring performance.

DD

[boggy]

Originally Posted by junya-eskimo

.........
I would post pictures but unless you get excited from a box with holes in it, there is not much point..eh

Please try, you may be surprised............. you also may publish your measurements before and after...

[junya-eskimo]

eh

killer...

I am in my friends place and i will look for a camera,,

Now this is the first(S) one i built. thier big. But small wiill also work well.. Its the depth that does it..

12 Inch deep..For the 125 i guess it will be less. but its all part of an equation...

look it up .. Helmholtz Tuned trap equation.. Takes some time to get it, but it works if you dont cut corners.

I recommend it as of today..

Heres the GREATEST bit..

I had the front panel with the holes off to fit the fiberglass. i put the mic there and measured it at zero..

I fulled it up, then measured again;; and it was -1 db.. (getting worried)

Then i put the pannel there and held it in place by hand...-1.5 (Now i am panicing)

Then i noticed if i push it harder to the box it dropped in level...

SCREW BY SCREW THE LEVEL DROPPED>..

- 1.5 per screw... I was go mad screwig as fast as i could, and then after the last one...Turned around and saw -18... iI cheaked that the mic was feedig the same level and it was..

After that i bounced all over the room and called everyone who would give a shit..

Anyway.. Now i am still testng to see if it can go lower..

Because of the spike at 59 we had there was a huge dip in 70.. The room has another big 49 spike in a corner that will be being drilled soon.

The dip in 70 is less but still there..

Anyone know any ides to brnig it back up? I thought to make a trap with no fiber so it resonates but that seem way too unstable to mix with.

Let me know..

John

[junya-eskimo]

Originally Posted by Glenn Kuras

Yes sir if done right they will work. Bryan and I built some (membrane tuned traps) and had them tested at Riverbank and also in our own lab/test room. Have some before and after of the testing?

sure..

But i will i will buid the 49 Hrtz one first so its not throwing anything off. Then i will be able to see what really going on..

But i will get it ..

[junya-eskimo]

Originally Posted by Karloff70

-18db??? F***ing hell.......how big are these things? I have a 120Hz issue, maybe I should consider this 'box with holes in' thing after all......was under the impression unless you paste plenty of it around it won't really do that much......

they are a mix.. 120x80 cm and 90x60 cm

To be honest, I dont know the effect of the small one yet, because i did not drill it.

The funny thing is i think the depth does it. I toyed around wuth the layers. From one piece of fiberglass to 6 .. (i have 5cm thick / 2").

The best was just full.. The one with 5 layers was -14 .. So go figure..

But if i chage the box size the math all changes. so a thinner trap can be tuned to the same frequency, but i guess it will be less effective. Good to know though if i ever wanna fine tune some small bump.. "Fine Tune Bass Trap".. Awsome.!!ee

Even that the level has now changed, it has only changed by -18 at that corner.. YES it has dropped all over . Listening sweetspot droped about -9DB. Which i guess will improve as the room is worked on...

As i have geen advised by the guru's. Positioning is very if not the most important.. A shift either direction will change it..

The Interesting thing is. There is obviously a center point to this energy. And I bet its bang its the middle of the center of that corner. The only way i could get that pioint would to build a triangular trap accross it.

That will be my next adventure to tune a corner trap, I dont know yet how i will calculate the space of it , but i am sure i'll figure it out.. I bet thats maddd effective.

[DanDan]

I really don't want to rain on a joyous parade here but....

Was the 18dB level change with a sine wave or pink noise?

It does seem that you may have achieved a tuned strongly absorbent scenario inside the trap. I achieved something similar myself with a tunable design.
However, apart from a few dB level change very close to it, it had no measureable effect on the room. I concluded that it would take lots of them to have an effect on the mode in question. A wall of them even.
Acoustics Forum • View topic - Helmholtz formula, is this incorrect?

Do you have any tests to show what effect your trap has on the room?
This is usually done by Waterfall. See a very hyped view of a very successful experimental DIY VPR here My Experiment with a Metal Panel Absorber


DD