Can I use these speakers

[rrpeterson3]

Good morning...

I have a question.  I have 2 Fi 18IB subs that I purchased for a IB.  I moved and my new home has no basement and a flat roof so the proper IB design not in the picture.

I purchased a pair of PC13s from SVS and I have been VERY impressed!  So much so that I am looking into building similar designs with the two 18IB woofers.

My question is can I used these two drivers in this "ported tube" design?

Please be as technical as possible.  Although I appreciate everyone's opinion, I need some really technical reasons and I know there are some great resources on this page.

Thanks,

Richard

[ThomasW]

Dec 27, 2013 10:07:14 GMT -7 rrpeterson3 said:

My question is can I used these two drivers in this "ported tube" design?

Not a good idea. Used in an IB the output is limited by the suspension. Used in a ported box the design is limited by the amount of heat the driver can tolerate. Since IB specific drivers have small motors they don't tolerate nearly enough heat to be used in other alignments.

[rrpeterson3]

Thanks for the reply.

Looking at the physical size of the magnet on Fi page compared to the traditional designs I suspected power handling was less, but the technical spec on the IB318 shows 550W RMS.  That seems like a high heat capability, especially at the RMS.  As you can tell I am trying to talk myself into this

[ThomasW]

If you look at the Fi IB3 website you'll see N/A (not applicable) under the "ported box" alignment section.

[rrpeterson3]

Yea, I did see that.  That is what lead me to this post.  Thanks...

[FOH]

Dec 28, 2013 7:27:48 GMT -7 rrpeterson3 said:

Looking at the physical size of the magnet on Fi page compared to the traditional designs I suspected power handling was less, but the technical spec on the IB318 shows 550W RMS.  That seems like a high heat capability, especially at the RMS.  As you can tell I am trying to talk myself into this

That 550w power rating is based upon an IB alignment, whereas the limits encountered within the subwoofer range are physical, not thermal.

That said, if you input a 20hz tone, at 550w, the driver could stroke back and forth all day. IB drivers encounter physical limits, not thermal dissipation issues, as they're much more bass efficient down into the deepest range, ... because they're not fighting the small box volume air-spring.

This is one component of the advantages of the alignment; dramatically less power required so lower motor current related non-linearity. Power requirements can be 10x difference. This is advantageous from the line side of the amplifier, thru the amplifier, and of course the low motor currents mentioned above.

As you've found, SVS offers some very impressive vented products. Their performance can be bested with an IB approach, but many can be plenty happy with the SVS offerings.

Best of luck

[rrpeterson3]

Thanks for taking the time to post this.  That makes sense now that you have pointed it out!