Too bad ventilation, isobaric cone to magnet? Plus what about the higher frequencies?

[DanielT]

I have a couple of speaker boxes that I have left over. They are not worth anything, I bought them for $10. I am thinking of mounting two Peerless SLS 10 (SLS-P830668) bass drivers in them, with an isobaric configuration. SLS 10 thrives well in at least around 45-50 liter sealed boxes. Isobaric, theoretically, allows for half the cavity volume. These speaker boxes are about 35 liters.

BUT what about the heat generated with a cone to magnet isobaric configuration? :

I mean it is a small chamber that one of the bass drivers pumps air/heat into. That heat is not going to disappear BUT on the other hand I don't know if it has any practical significance? Do you think it could get too hot and affect the sound of performance/quality?

My second question. With a cone to magnet configuration do you think there will be problems with a crossover point around 500 Hz? One SLS 10 played up to 500 Hz is perfectly fine but two in cone to magnet isobaric?

I was thinking SLS 10 together with Peerless tc9 broadband driver:

This is how the SLS10 is vented:


If I remember correctly, you @Duke have commenting about this with heat generation and isobaric, but I don't remember what you said?

 

[digitalfrost]

I built an isobaric woofer using Peerless SLS-8, cone to magnet configuration. It worked well and I had no issues.

 

[a4eaudio]

...My second question. With a cone to magnet configuration do you think there will be problems with a crossover point around 500 Hz? One SLS 10 played up to 500 Hz is perfectly fine but two in cone to magnet isobaric?

I know of at least three two-way speakers using isobaric configuration (pretty sure all were cone to magnet) and they all sound very good. Woofers are probably playing up to 1.4kHz to maybe even 2kHz.

 

[DanielT]

I built an isobaric woofer using Peerless SLS-8, cone to magnet configuration. It worked well and I had no issues.

I know of at least three two-way speakers using isobaric configuration (pretty sure all were cone to magnet) and they all sound very good. Woofers are probably playing up to 1.4kHz to maybe even 2kHz.

Thanks for the tip!

I have a cardboard casting tube. I can use that between the drivers. It actually fits perfectly in diameter. Of course two baffles have to be sawn out and placed on both ends of the tube/SLS10 drivers. Plus supporting struts, braces between the baffles that then hold the tube stable in place are needed.
Plus a small separate sealed box for the tc9. Ideally some braces in the speaker box itself wouldn't hurt either.

At 500 Hz crossover point, C-C between the SLS10 and tc9, if they are placed as close as possible, will be 1/4 wavelength. That's ideal as far as I know. A LR-4 active crossover will be used.

The tc9 should also be pushed in a bit on the baffle so that time alignment with the SLS10 will be good BUT this could end up to be an overkill project that never gets done. That's my Achilles heel, good at starting projects, terrible at finishing them.



Edit:
That's the theory, then this with the practical aspects.
Missing such a fundamental aspect as checking whether two SLS10 10 cone to magnet fit in the boxes I have? Embarrassing. The answer to that is no. The speaker boxes are not deep enough:

In that isobaric case, I need to make the speaker boxes deeper and well that would look a bit crazy. I'll pop in an SLS and test. It works anyway. 35 liters is not optimal but I don't know how it will be with bass FR in my small living room/listening room. It will require a lot of EQ regardless of how big or small boxes I pop the SLS10 in.

Those SLS10 are no SPL monsters. They have a fairly weak motor, 70 watts power handling. It would have been better motor power with isobaric, but since I don't play at such a high volume in the apartment (consideration for neighbors) it doesn't really matter in practice. Good hifi sound at normal listening volume and I'm satisfied.

Of course making completely new speaker boxes is an option. However, I thought it would have been fun to do something with the Infinity speaker boxes, now that I still have them.
The original bass driver in them is actually no bass driver in my eyes. They roll off around 70 Hz. No bass power whatsoever. The most ridiculous small 8 inch bass driver motor I have ever seen.