8" woofers 40-250hz

Well.... I think this is interesting:

"Even in the mid-bass at 280 Hz and lower, the noise can be around -14 dB (20% distortion), about half as loud as the music itself, before we hear it."

It indicates that we need to pick some really bad drivers to ruin bass below around 4-500Hz - unless we do not EQ the in-room response and the drivers or amplifiers run into either max excursion or clipping.
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The idea that line arrays drop only 3dB per doubling of distance is only valid in the near field, and is the result of level lost due to destructive interference. There is only loss of SPL in the near field compared to a point source.

The near field distance can be defined by the following relationship:
D=1.57 L squared/λ
D is the distance to the far field transition
L is the physical length of the line source
λ = the wavelength of the frequency in question (all lengths in identical units).

At 250Hz the "line array" will be out of the near field cancellation region within a few meters and drop at 6dB per doubling of distance.
Just saw this, thanks it is interesting.
Thanks all for ideas guys, they have been both on and over my level of understanding but I try as much as I can.:cool:
I have been thinking a bit about this and I think I need more of your help with some basic speaker theory.

Ive been building so much speakers over the years with different results and many times without the knowledge I should have had. Practics was more fun than theory, I admit that :D
This time I want to learn more, hopefully to maybe get a better result out of this speaker. I also need to know what it is I really want the result to be like.
And I can generally say that in the bass/midbass I want something in between that classic PRO and Hifi-sound, cant explain it better than that. I want to play it loud but still super hifi when I feel like it.
In the midrange and upper frequencies im happy with the speakers I have and the sound they give me.

Then back to the 8" woofers and a few questions..
If I go for a "PRO driver" that has a Qts or a fs/Qes that theoretically fits better with a ported enclosure but simulates "good" in a 20litre sealed box.. Is it that simple that it also works good in that kind of box? Whats the trade-off here?:unsure:

For going 6 units per side, I have a few 8" drivers that simulates good as far as I understand it, regardless sensitivity etc.

Dayton RS225P-4A, Its a little bit to big in diameter but could probably be squeezed in.

Seas H1192-08 CD22RN4X, also to big but could probably work. Looks good to me, whats the disadvantige?

Faital PROn 8RS340, been discussed, good in size and seems to want very small boxes, good or not ?

18sound 8nmb420, discussed and interesting good in size but is it anyone but Hydrogen Alex that think this is the best for me?

I dont think this one have been discussed here, cheap and good in size but its maybe crap?
Fane Sovereign Po 8-225

More of your thought are very appreciated :)
What hasnt been discussed much is my subwoofers.
As told before they are open baffle and I would like them to play only the lowest freq. I like how they do that but I dont like them over 50-60hz.
Also want all "hearable" sound coming from the 3-way speaker.
I have much options with the Hypex amps and the 18"s CAN play higher in freq. and meet probably any 8" i choose but I think you got it how I think.
maybe right Sica for the task


and quite cheap

Agree :) The problem is the size of the room, too small and not enough space behing and .front of the baffle to heard the bass. 50Hz is 6.8m wavelength.
But why do you write this in this thread ? You are breaking dream of a lot of people here.
Frequency response below Lambda=2 x longest wall measurement has 6dB/octave rise slope. 50 Hz has length 6.8 m, as you said. Any room below 3.4m longest measurement (I would spread that close to 4m) will give flat to low 40-ish Hz and 6dB downward slope below (if closed box used),
I just discovered that web store few days ago. Anybody has experience with them?
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Frequency response below Lambda=2 x longest wall measurement has 6dB/octave rise slope. 50 Hz has length 6.8 m, as you said. Any room below 3.4m longest measurement (I would spread that close to 4m) will give flat to low 40-ish Hz and 6dB downward slope below (if closed box used),
Yes but I talk about perception. In a large room the bass is better to my ears. It is my experience with the same speaker in two different room. In smaller rooms I thought the speaker does no bass (F3=50Hz closed box) but in the larger room, I heard an other speaker with plenty of bass. The large room was treated acoustically with bass trap and other materials. In small rooms I notice best bass perception in the diagonals.
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Thanks for your ideas, I have build OB speakers with 4 x 12ob150s but I sold them. I have also build 10-15 different OP baffle spekers in price range from cheap to very expensive during the last 20 years. Now I bought two cabinets that I would like to try a different approach with.
Hello Theo.

Sorry for the tangent - I'll keep it short to avoid any derailing if your thread. Nice build you have!

I noted you have a fair amount of experience with OB including with 12ob150s and apparently with Acoustic Elegance Dipoles ( from t
your system drawing). How would you compare them for this same frequency range (40-250Hz) in OB? Other drivers you liked better?

Thank you!
@LewinskiH01 I send you a PM.

To the topic again and this driver feels good to me, Seas think its the right for my application(and budget).
Quite light cone, good transients and with a little Eq should go deep enough or atleast close to my initial goals.

Except that some think the whole project is not so smart, and that is fine... Am I missing something with this Seas driver? With my limited experience on the topic it doesnt looks like that.. is it the best driver for little under 200euro per driver?
Vas is high, but again - you are eq’ing an active system, so: (y)

It won’t be as dynamic-sounding as a more efficient driver though; it’s only 90db below 300Hz:

As to it being the “best” given your desires and price-point? I don’t think anyone but you could make that determination. Considering the number of drivers you are purchasing I would think the best idea would select/purchase a single driver and hear for yourself with a mock-up comparable volume enclosure for a single driver eq’ing as required. Maybe even doing that with a few different drivers.
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You’ve got eq. (Just boost the low freq. response to get your “deep”) - at that point it’s mostly about excursion/Sd and power . ;)

Of course that’s no guarantee that even if eq.ed properly that you’ll have the best sounding result (for you).

There are several HiFi 8” drivers available that all have similar spec.s.. I might choose this one out of the group:

IF I wanted more excursion then I’d look to the 4 ohm sub from SB.

I’d still pick the Dayton driver I mentioned, though it has a bit less excursion (which might not matter with 6 per loudspeaker). 18Sound also has some nice lower Mms 8” drivers. Both options are more efficient above 120Hz, and will sound a bit more dynamic as a result.
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I don't know were is your project but I have the 8nmb420 at home in a 20L closed cabinet bookshelf . This is an excellent driver very dynamic and transparent. Vocals are awesome on this I really prefer it against my revelator 15W/8530. I would put it has a midrange in your project, but not has woofer/subwoofer (or maybe make 2 separated enclosure and make an hybrid 8nmb420 closed/ and something else in bassreflex There is a.
There is a ridiculously chip driver but some french guys are really impressed with it : STX W.22.200.8.MCX and are using them up to 600 in woofer closed or sealed. Looking at the price VS the price of your project, it might be worth it to buy a pair and try them ...
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