Diffuser qrdude, can you help me?

[zonelabsmx]

Hi, i´m creating acoustic solutions for my project studio and i started to read your posts, i want to make a qrd diffusor and i use the qrdude and these were the results I think you can help me about if these measures will work in the range that the calculator shows (550-6880 hz) correctly, if this going to works fine with this measures, greetings and thank you very much


Happy New Year from Mexico

Pd: Sorry for my English

[terry j]

I am sure Bill will be along soon, so I think it may help if you could ask an exact question. It may be only me, but it is hard to know what you are exactly asking.

I think you are asking if the design given works within the frequency range you mentioned.(???)

Then yes. The program 'spits' out the answers based on the initial conditions.

Sorry if I have misunderstood you, but it does seem hard to figure out what you want to know.

[collo]

Hi there zonelabsmx,

I'm happy to help with your queries, but as Terry mentioned, you might need to be a bit more specific.

Have you read the qrd overview page and user guide linked to from the download page? They should answer your question about how the frequency range is defined.

[zonelabsmx]

Originally Posted by collo

Hi there zonelabsmx,

I'm happy to help with your queries, but as Terry mentioned, you might need to be a bit more specific.

Have you read the qrd overview page and user guide linked to from the download page? They should answer your question about how the frequency range is defined.

Yes, thanks,pardon my English, perhaps the question seems more complicated than it is because I do not write very good English, my question is about to be certain about constructing the diffuser with these measures that the program gives me the diffuser will actually respond in this range that the program show me (550-6880hz), some people have told me that qrd calculators not work exactly like in real life, and I want to be certain it will work as the calculator says, I hope I have been more specific, thank you very much for your answers and many greetings

[bpape]

Just remember that the 'cutoffs' are just that - the point where it no longer diffuses at all and acts essentially as a flat surface. The range where it provides smooth diffusion is narrower.

Bryan

[collo]

To expand on what Bryan said....correct diffusion occurs at multiples of the design frequency. If you look at the scorecard for your design, you get:
1100hz, 2200, 3300, 4400, 5500, 6600Hz
This gives your best operation from 1100 to 6600

From 1100 down to 550hz, and from 6600 up to 6880, you get scattering.

Have a look at the pdf on acoustic data for the N7 on the RPG site to see a graph of typical QRD diffuser performance.

You also should try and have the fin width small in relation to the well width. You have 10mm fins with 25mm wells, which perhaps could be improved on.

[zonelabsmx]

Originally Posted by collo

Correct diffusion occurs at multiples of the design frequency. If you look at the scorecard for your design, you get:
1100hz, 2200, 3300, 4400, 5500, 6600Hz
This gives your best operation from 1100 to 6600

From 1100 down to 550hz, and fromm 6600 up to 6880, you get scattering.

Have a look at the pdf on acoustic data for the N7 on the RPG site to see a graph of typical QRD diffuser performance.

You also should try and have the fin width small in relation to the well width. You have 10mm fins with 25mm wells, which perhaps could be improved on.

Thank you very much for your answers, which measure you reccomend me for the fins in this design?, thanx a lot to all of you!

[collo]

Originally Posted by zonelabsmx

... which measure you reccomend me for the fins in this design? ...

The program defaults to 3mm, which is a good size for 25mm wide wells - you can use a variety of materials, but at this thickness, ply is stronger than MDF.

Even 5 or 6mm would be better than 10.

[zonelabsmx]

Originally Posted by collo

The program defaults to 3mm, which is a good size for 25mm wide wells - you can use a variety of materials, but at this thickness, ply is stronger than MDF.

Even 5 or 6mm would be better than 10.

Thanks for your answers, and about construction: can i use a general well depths of 60 mm each one corresponding to the height of the periods and fill the spaces behind with something like spray foam? (to save weight) this would work?, i will going to use plywood for construct the diffusors.

Thank you very much!

[collo]

Most constructions use a plate for the well floor rather than a solid block.
If you feel that the material used is a bit thin, you can fill the back side with expanding foam for extra support and resonance control. The attached N7 pic shows the idea

From the Export / Report for your design:
Well depths in mm: 0 14 57 128 71 43 43 71 128 57 14

(You can get the same frequency range from a panel that is shallower if you use the Advanced options)

[zonelabsmx]

Originally Posted by collo

Most constructions use a plate for the well floor rather than a solid block.
If you feel that the material used is a bit thin, you can fill the back side with expanding foam for extra support and resonance control. The attached N7 pic shows the idea

From the Export / Report for your design:
Well depths in mm: 0 14 57 128 71 43 43 71 128 57 14

(You can get the same frequency range from a panel that is shallower if you use the Advanced options)

I deeply appreciate your answers, Did you refer to do this to get shallower well depths?





If i do the diffusor with this characteristics, this going to have different audio effects or have the same result?

Thanks!

[collo]

That is the one I was referring to (N11+2). It will have the same effect as the standard N11.

If you are not going to partner the panel with its inverse, this is the one I would go for. Build depth 100mm (not counting thickness of backboard)

If you are going to include the inverse, go for an N11+4 and its inverse N11-4. Build depths 128mm for both panels

Contrast this to the standard N11, where the build depths are 128mm for the normal and 157mm for the inverse.

[zonelabsmx]

Originally Posted by collo

That is the one I was referring to (N11+2). It will have the same effect as the standard N11.

If you are not going to partner the panel with its inverse, this is the one I would go for. Build depth 100mm (not counting thickness of backboard)

If you are going to include the inverse, go for an N11+4 and its inverse N11-4. Build depths 128mm for both panels

Contrast this to the standard N11, where the build depths are 128mm for the normal and 157mm for the inverse.

Thanx collo!, excuse me my ignorance please but, what´s the difference or the advantage of make inverse panels in our sequences?,

Like this?



Thanx!

[collo]

The inverse panel is used to reduce the lobing that occurs when multiple panels are used in an array. If you're only doing a few, you need not worry about it too much. More detail about this on the qrd overview page

[zonelabsmx]

Originally Posted by collo

The inverse panel is used to reduce the lobing that occurs when multiple panels are used in an array. If you're only doing a few, you need not worry about it too much. More detail about this on the qrd overview page

Wow!, Excellent! , Thanks a lot collo and all other, you helped me much!, happy new year!

[collo]

Happy to help. Don't forget to post some photos during the build....

[zonelabsmx]

Originally Posted by collo

Happy to help. Don't forget to post some photos during the build....

Excellent!, I´m going to upload the photos as soon as start the construction!

thanks!