Cubo Sub

kasey wrote: I see you said that a 4 ohm sub will perform different than a 8 ohm. How is this possible?

This is not actually what I said

If you look at the T/S-parameters of the 8 and 4 Ohm version of the mentioned B&C drivers, you'll see that a lot of the T/S-parameters are actually quite different.  So this is what my previous post suggested. Hope that clears things up.

Best regards Cubo

Oh I see. Your comment was directed to these particular woofers! I didn't know these woofers have different t/s paramaters when it came to their impedances. Thanks for taking the time to clear that up.

Personally I've never seen an 8 and 4 Ohm version with the exact same T/S-parameters.

The 4 Ohm version will see 1.414 times as much current for the same power as the 8 Ohm driver, to safely handle this extra current the voice coil wire needs to be different (thicker, shorter). As a rule of thumb the BL (Newton/ Ampere) is 1.414 times as low. The Re of a 4 Ohm driver is usually not exactly half that of the 8 Ohm driver, therefor Qes will also be different. So now you have a different BL, Re, Qes and Qts so that the 4 Ohm driver will behave the same as the 8 Ohm driver. The offset Qes can but doesn't have to be compensated for by a different Vas, etc.

Best regards Cubo

Cubo15 wrote: Personally I've never seen an 8 and 4 Ohm version with the exact same T/S-parameters.

The 4 Ohm version will see 1.414 times as much current for the same power as the 8 Ohm driver, to safely handle this extra current the voice coil wire needs to be different (thicker, shorter). As a rule of thumb the BL (Newton/ Ampere) is 1.414 times as low. The Re of a 4 Ohm driver is usually not exactly half that of the 8 Ohm driver, therefor Qes will also be different. So now you have a different BL, Re, Qes and Qts so that the 4 Ohm driver will behave the same as the 8 Ohm driver. The offset Qes can but doesn't have to be compensated for by a different Vas, etc.

Best regards Cubo

I understand what you are saying now, and I definitely learnt something, but in terms of power, you're saying a 4 ohm version sub rated 1200watts will sound different as compared to the same model 8 ohm version sub rated 1200watts if they are tested in the same enclosure? I mean if two different 1200watt amplifiers are used for each sub (a 1200watt 8ohm amplifier, and a 1200watt 4ohm amplifier). I honestly thought that if you give a speaker its rated power, it will sound the same regardless of its impedance (because you match its impedance to the amplifiers power rating).

Hi,Cubo15. Is the RCF LF15G400 a good driver for the cubo sub? The mms parameter is OK?
Your help will be very appreciate.
thanks in advance my friend.

you're saying a 4 ohm version sub rated 1200watts will sound different as compared to the same model 8 ohm version sub
rated 1200watts

Ideally it does not but power handling is simply a measure of how much (thermal) energy the driver can handle before it burns up. If Qes, Le, etc. are different enough, it can affect the sound, although these differences are least noticeable in bass and sub enclosures.

ss the RCF LF15G400 a good driver for the cubo sub?

As far as 15" drivers go, it's actually a pretty good Cubo Sub driver. For a 15" driver that's a very respectable Mms.

Best regards Cubo

Hey Cubo,

Sorry if this has been asked before (couldn't find anything on it) but what do you think of the Celestion FTR15-4080HDX being used in a cubo sub? I can get a pair for reasonably cheap and was thinking of building the subs with these and then upgrading later on to 18s when I can afford them. The subs would be used for mostly house and disco at open airs.

Thanks!

The Celestion is a very decent 15" driver and although I would normally recommend Cubo 15 Extra Extended as the best match, I've seen lesser 15" drivers used successfully in Cubo Sub. So if those drivers survived, these definitely will. The attachment shows Future Pussy Sound System, 8 x Cubo Sub loaded with the Eminence 3015LF (if I recall correctly).

Cubo

Amazing thanks very much for the info!

I want to get data for hornresp