Dual drivers, One or Two chambers in enclosure?

[panduro]

Maybe a simple question, but somebody gitta ask it 😂😂😂😂
If making a speaker with two midbass drivers(2225), where both drivers cover same frequency range(35-700hz) What are the advantages/disadvantages with having One room in a Big enclosure(10cf), compared to having 2 chambers of 5cf each?

Best regards

panduro

[berga12]

Theory: If there are T&S difference due to building/material tolearances, separate chambers have the benefit to isulate every speaker from the back emission of the other (a bit different, not in phase, impedance minors differences etc...)

Practically: in that range, no one will be able to recognize those difference in the final acoustid emission, so the driver differences are negligible.

2 chambers keep the enclosure strongher with the need of less bracing.

[Flodstroem]

One enclosure could have the benefit of a better lower bass extension. If you can make a simulation of the speaker:
one with an internal volume of 5 cf for one speaker
and another with an internal volume of 10 cf with two speakers
For the 10 cf enclosure, calculate T/S as:
same Bl,
4 ohm or 16 ohm, your choice
cone area is doubled
rest of the parameters is the same as for one speaker

Compare both simś and look for a lower bass extension in the 10 cf enclosure if any?

[more10]

A PPSL (Push Pull Slot Loading) box will reduce distortion in bass. It is not recommended for midrange tough. I have not heard the 2225, but I believe the ribbed cone will not sound good in midrange anyways.

[audiomagnate]

One of my favorite speakers, the ADS L1530, uses the two chamber approach, so maybe there's something to it. That surprisingly small speaker did 14 Hz extremely well.

[ivica]

Maybe a simple question, but somebody gitta ask it 😂😂😂😂
If making a speaker with two midbass drivers(2225), where both drivers cover same frequency range(35-700hz) What are the advantages/disadvantages with having One room in a Big enclosure(10cf), compared to having 2 chambers of 5cf each?

Best regards

panduro

Hi panduro,
I do not think that to use such combo over 300Hz, as mid bass wolud about 3dB lass then bass region
Regards
Ivica

[panduro]

hello all and thanks a lot for sharing your knowledge,

im asking this question because I've never made a speaker with dual bass drivers before. active xover. the orientation of the bass cabinet im planning is very similar to the 4435(woofers side by side), and im thinking about making the cabinet deeper on the side than the other(making it toe in when facing straight). this would be considerably easier if the two woofers can share a share the same room en the enclosure. if it has no severe drawbacks, compared to the one chamber pr driver setup.

berga, thank you for your info, that makes it more clear to me .

flodstroem, i tryed simulating it, but i can only do it on an online program that i found, im a mac user who hasn't found a good sim program ? my sim did not show any differens in low extension?

more, thanks for making me aware of that option also, i will read about it, maybe for a future project.

ivica, would you be kind and explain to me what the reason for that is? im using these drivers in there current cabinets(2x2225 + 1x2445) although not high end , it sounds good with a active xover .

magnate, it seems like consensus is to go with one chamber pr driver, maybe i should move slowly away from my toe in idea and just go square

best regards

panduro

[Flodstroem]

One enclosure could have the benefit of a better lower bass extension. If you can make a simulation of the speaker:
one with an internal volume of 5 cf for one speaker
and another with an internal volume of 10 cf with two speakers
For the 10 cf enclosure, calculate T/S as:
same Bl,
4 ohm or 16 ohm, your choice
cone area is doubled
rest of the parameters is the same as for one speaker

Compare both simś and look for a lower bass extension in the 10 cf enclosure if any?

I forgot the VAS, its also doubles if calc. with two speakers.
I have done an instant sim with two 2225H in a 10 cf (283 lit) in a made-up box with following internal dimensions: 120 cm x 50 cm x 47 cm and you can see the results here in this file: But there is a lot to do for the shape of the box. Also I dont know what type of box you are thinking of.........
2225H in a 283 lit ported box tuned to 30 Hz.pdf

[panduro]

Thank you very much flodstroem,

That is a awesome sim, so much info i dont have the knowlegde to interpret .

would you be willing to do A sim for me If i drew the plans and send Them to you(it Will be a scanned image of a paper drawing as Im a computer idiot)? Only If Its not to much trouble!

Best regards

panduro

[Flodstroem]

Hello "panduro" in Københvn
Of course I can do a sim for you. I need the specified internal dimensions (H x W x D)
I also need the positioning of the two LF speakers including the port (ports?) and if you intend to have the HF compression driver inside I also need the position of it..

Also post the internal dimensions of the smaller cabinets (5 cf) you wore considering in your first post. If you do I also can do a sim so you get something
to compare.

Im also a Mac-man but using Windows-XP on Oracleś virtual PC https://www.virtualbox.org/ (I can recommend it) My simulation program are Martin Kings calculating sheets
My calculating program is a demo version of the MathCad and this demo program is for free. Its an older version and last Windows for it was the "XP" version. The drawback is that I cant save my sim sheets so I had to print them as .pdf files for to save them. Its a little bit more complicated but best thing is, it works

[ivica]

hello all and thanks a lot for sharing your knowledge,

ivica, would you be kind and explain to me what the reason for that is? im using these drivers in there current cabinets(2x2225 + 1x2445) although not high end , it sounds good with a active xover .
....?panduro

Hi panduro,

Drivers mutual coupling depends to the driver relative distance...
Regards
Ivica

[panduro]

Tak hr.norge,
ill do that tomorow and check out the sim software when time permits.

hello ivica,
To make sure Im getting your point, driver coupling/boost happens If the centers of the drivers, is less distance appart then 1/4 of wavelenght. In my case that Will limit the coupling to below 200hz. Good point, ill have to correct that via my xover i guess. Or should i try to flatten out the frequency response with box size and tune it for a more gradual Roll off?

best regards
panduro

[ivica]

Tak hr.norge,
ill do that tomorow and check out the sim software when time permits.

hello ivica,
To make sure Im getting your point, driver coupling/boost happens If the centers of the drivers, is less distance appart then 1/4 of wavelenght. In my case that Will limit the coupling to below 200hz. Good point, ill have to correct that via my xover i guess. Or should i try to flatten out the frequency response with box size and tune it for a more gradual Roll off?

best regards
panduro

Hi panduro,
YES, I think -3dB, is somewhere round 1/2 wavelength center to center, so round 40cm, or lambda 0.8m,
So 345/0.8 = 345*1.25 Hz = 430Hz....so 300Hz crossover freq. Is OK.
But more ,????

Regards
Ivica

[Flodstroem]

panduro, I have done 2 simś for you. But....... Im unsure of the tuning frequency for two x 2225H. I havnt checked what is the most optimal tuning frequency for such cabinets like those you send a drawing of. If you choose other tuning frequencies, modifications of the ports would be necessary.

2225H x 2 panduro mod A 283.5 lit tuned to 30 Hz.pdf2225H B version angeled panduro 283.5 lit tuned to 30 Hz.pdf

There is practically no differences between the two models, only different port tubes as far as I can see...............

[panduro]

hello Ivica and Flodstrøm,
thanks for your help and guidance, this newb needs it

ivica,
there must be something im missing, im not sure how you come up with those numbers if i look at flodstrøms sim, -3 is around 140hz and the response starts to drop very slowly from 300hz and down. so to me it looks like i have to boast a bit from 200 and downwards to get it flat and a bit more to get a bit heavier target curve.
are you factoring in some cabin gain or what am i not getting?

hello flod and thx for doing the sims, its much appreciated!

not knowing a lot about this, i dont know how to interpret what i see, other than the respons curve looks good to me. i do think ill see if i can lower the tuning a bit, to get a more gradually decanting bass respons.

best regards

panduro