Dayton ND-90 Enclosure choice

[Adam Bernau]

Dear DIY colleagues,

I am designing small speakers for PC/ MP3 nearfield use and i have choosen the Dayton ND-90 8 ohm speakers for this project. The first version will use one driver per box and i wanted to ask you for recommendations of the enclosure and volume.
One of the reasons why i have choosen this driver is also that it should have good bass extension and low distortion under load.I will be driving them with 2x50 W clas D amplifier, so power reserve i have and the low sensitivity wouldn´t be a problem.
What i don´t know is if i should go for closed or vented enclosure and what volume the optimal enclosure should have.

Thank you for any possible recomendations and/or comments for the box and vent.

Regards

[sreten]

Hi,

No way can such a small driver handle 50W without being c/o to a sub.
The ND90 is a rebadged Aura NS3, see Zaph|Audio

A 1.5 way might be an idea for power handling and baffle step,
the TS parameters indicate around 3 or 4 litres sealed for two,
and that vented is not a good idea,though its possible with an
unusual alignment.

Having said that for near field with one driver a 2L box tuned to 70Hz
(with some sort of low bass filter for ~ 50Hz and below) would give
around 3dB of baffle step compensation, peaking around 150Hz
and could work quite well if the driver is unequalised.

Use 2L boxes and try 70Hz tuning or settle for sealed.

rgds, sreten.

[Adam Bernau]

Sreten,
Thanks for the help. 3-4 litres for two ? I am planing to use single speaker in each enclosure, so it means 1,5-2 liters per each closed enclosure ?
The reason why i opted for the 2x 50 W amp was because most of the Tripath Amps rated at 15 or 25 W per channel seem to have a significantly high distortion levels when they are working close to their maximum output. My idea was that i will use more powerful amplifier and let it work comfortably in the zone where is the distortion minimal.
By 1,5 way you mean a woofer cut around the 70 Hz in the same enclosure if i understand correctly. Do you have any recomendations from the Dayton Audio range ?

Thanks again

Adam

[gooki]

Using a more powerful amp is fine, just keep a close eye on the volume control.

[Adam Bernau]

Originally Posted by sreten

Hi,

No way can such a small driver handle 50W without being c/o to a sub.
The ND90 is a rebadged Aura NS3, see Zaph|Audio

A 1.5 way might be an idea for power handling and baffle step,
the TS parameters indicate around 3 or 4 litres sealed for two,
and that vented is not a good idea,though its possible with an
unusual alignment.

Having said that for near field with one driver a 2L box tuned to 70Hz
(with some sort of low bass filter for ~ 50Hz and below) would give
around 3dB of baffle step compensation, peaking around 150Hz
and could work quite well if the driver is unequalised.

Use 2L boxes and try 70Hz tuning or settle for sealed.

rgds, sreten.

Sreten,
Thank you very much for previous help.
If you can, please be so kind and give me one last advice
I have the almost finished enclosures now, they measure empty 1,8 liter each. They are very nice looking, made from 3 mm aluminium. I will use some sticky bitumen to damp the possible mid/high frequency resonances. I think that if if i substract the driver and damping volume, i can get somewhere around 1,5- 1,6 l. Is this enough to make it closed ? I somehow like the closed box idea, correct me if i am wrong but i imagine that the behavior of hermetically closed air volume will somehow help the stability of the driver behavior under load and maybe the impulse response.
Do you think that i can use the driver unequalised or do you reccomend some type of filter ? The beauty of this design for me must be its simplicity and small space taken on the table. Do you think that it is better to use polyfil or mineral wool ? I have read some interesting article about isothermic/adiabetic behavior of the air volume depending on the amount of damping material, can you recommend me what amount of what material i should use to get the "virtualy bigger" enclosure ? Do you think that this effect is significant ? I am limited to my kind of artistic metal enclosures and i can only acomodate one or two back firing ports of 30 mm max diameter, lenght limit is around 100 mm.
Thank you very much for help, i am an architect so feel free to PM me about any consultation of any home/interior/ product design issues that you may have so i can help you for exchange.

Regards

[sreten]

Hi,

They will be fine sealed. Porting I don't recommend but is possible.

With two boxes do a binary search comparing the two boxes to find
the amount of stuffing that gives the best bass, too much will kill
bass so its a much as possible that works.

rgds, sreten.

Try checking NS3 / ND3 differences at Zaphaudio.