Using only 1 driver of a 2 x 10" push/pull (enclosed) subwoofer, technical explanation?

[voodooless]

Don't really know, find those Acoustic Elegance IB10AU almost incredible for their size (including distortion and Faradey ring's).
Feal free to search and propose better/cheaper/or a combo of the two. Availability is a bit low on those I proposed.

Oh, it’s a fine woofer. I’m just saying there are alternatives. Especially outside of the US the AE products aren’t really interesting due to high shipping and import costs.

 

[Geertidow]

If you were to have the option of using one woofer and closing the other port / one woofer with passive diffuser / two active woofers, what would you choose?
The OP was very different and I did already learn a lot, but something to think of in the future.
I found out the inner voluime of the subwoofer is approximately 110 liters.

 

[voodooless]

If you were to have the option of using one woofer and closing the other port / one woofer with passive diffuser / two active woofers, what would you choose?

That will depend on the requirements you have for a sub, including how much space you have for it. You keep asking for a10” woofer, yet your enclosure is relatively large with 110 liters. Why not go for a 12” woofer?

 

[Geertidow]

I don't think a 12 will fit.
The width is not too great. I'll upload some photo's soon

 

[JRS]

The disconnected speaker acts as a passive radiator. You now have a ported subwoofer, with the passive radiator as the port.

To find out what that does theoretically to the frequency response would require knowing the internal volume and the speaker coefficients and putting them in a modeling program or doing the math. If the port tuning works out right it could extend the low frequency response. Since the speaker was not intended to work in this fashion the port tuning is probably not optimal, but by happy coincidence it matches well with your room response.

Bingo. The apparent Vab doubled while adding vent. He loses efficiency: 3dB from missing woofer at higher frequencies and another 3dB from doubling the effective resistance. So loses considerable max SPL potential at higher frequencies but may get it all back at lower ones via the output of the PR. Not an expert but that's my best guess early in the.morning.

 

[Chrise36]

It is a weird design because an isobarik closed box with these drivers would need only 20l of volume. You actually have a closed box with a driver with lower fs sensitivity and stiffer suspension. If you like the sound keep it like this. What are you after more spl more bass extension flatter frequency response?

 

[voodooless]

It is a weird design because an isobarik closed box with these drivers would need only 20l of volume.

How did you reach that conclusion? The driver has a VAS of 156l. Isobaric would half that. Even then a 20l enclosure would be way too small especially with the low Qts. What he has isn’t even isobaric as far as I can understand. Isobaric is a massive waste of resources anyway, so I would not recommend that for modern designs.

 

[Chrise36]

How did you reach that conclusion? The driver has a VAS of 156l. Isobaric would half that. Even then a 20l enclosure would be way too small especially with the low Qts. What he has isn’t even isobaric as far as I can understand. Isobaric is a massive waste of resources anyway, so I would not recommend that for modern designs.

It comes from speakerdatabase sim. Same plane push pull does not work only isobaric.

 

[Chrise36]

If you were to have the option of using one woofer and closing the other port / one woofer with passive diffuser / two active woofers, what would you choose?
The OP was very different and I did already learn a lot, but something to think of in the future.
I found out the inner voluime of the subwoofer is approximately 110 liters.

Do you have any photos?

 

[Geertidow]

Do you have any photos?

Yes soon! It's not isobaric, the divers are just mounted in oppositely in the same plane but they move in the same direction.

Pics will follow asap!

 

[ZolaIII]

It comes from speakerdatabase sim. Same plane push pull does not work only isobaric.

Please explain in what did you export data and did the simulation? They offer 39L closed box simulation only directly.

 

[voodooless]

Please explain in what did you export data and did the simulation? They offer 39L closed box simulation only directly.

I don’t think that box size is very specific. It also shows me a 39l box with other 10” woofers.

 

[Chrise36]

Yes soon! It's not isobaric, the divers are just mounted in oppositely in the same plane but they move in the same direction.

Pics will follow asap!

Then it is a closed box with 2 drivers shared the same enclosure . Why is the one mounted reversed?

 

[Chrise36]

I don’t think that box size is very specific. It also shows me a 39l box with other 10” woofers.

I will try to simulate in winisd to confirm

 

[ZolaIII]

I don’t think that box size is very specific. It also shows me a 39l box with other 10” woofers.

As my second sentence says that's the only sim they provide directly (disreging of cone diameter).

 

[Chrise36]

According to winisd vented box with 108 l is the optimum that is why the "passive radiator" configuration works better.

 

[voodooless]

According to winisd vented box with 108 l is the optimum that is why the "passive radiator" configuration works better.

You could just aim the PR version by inputting the PR data fields from the woofer TS parameters. That should give an approximate performance of the system with one woofer disconnected. My guess is it will be sub-optimal. Normally you’ll want a lower fs for the PR, more mass. It may show why this version was preferred though vs the dual woofer closed version. “Works better” is always a trade-off. The closed version will have more headroom, but may also need more correction. Since the OP has access to DIRAC it a bit surprising the other version performs better.

@Geertidow, did you rerun DIRAC after you made the changes to the sub?

 

[Vladimir Filevski]

... The drivers are just inserted oppositely on the same plane. So one driver is screwed in normally, the other with the magnet towards the outside (and connected reversely so they move the same way).

When both woofers are connected (parallel or serial), that configuration cancels second harmonic distortion.
When one woofer is disconnected, it is a vented enclosure with passive radiator (and without cancelling distortion). But that is a very wasteful use of resources (woofers) - genuine passive radiator is much cheaper than ScanSpeak woofer.

 

[Chrise36]

Why were the drivers wired at 2 ohm? 4 ohm is optimum for the hypex.

 

[voodooless]

Why were the drivers wired at 2 ohm? 4 ohm is optimum for the hypex.

Probably because otherwise you’ll end up with 8 Ohm, which is less optimal than 2 Ohm power wise.