Couple ?'s regarding IB 15's....

[fish]

A couple more questions:

Will there be an audible difference in output with 300w/pair vs. 500w/pair on the IB15A's?

In a thread towards the bottom of the page started by Grim0013 he asks if these can be built with 8 ohm coils. John said he had some at the time, are there still any left?

[simon5]

Well, between 300W and 500W, you will have about 2 dB in output difference. I don't know how sensitive is your hearing, but 2 dB isn't that much, slightly louder but hard to notice I'd think.

Well John still make IB15 in 8 ohms, so I guess it wouldn't be much troubles to do IB15A in 8 ohms, he could probably switch the coil. I will ask him about it.

[fish]

Ok, thanks Simon. I appreciate it.

[simon5]

Just talked to John, he confirmed that he can do them in 4 ohms or 8 ohms.

[fish]

Alright! Sweet!

[fish]

Sorry, but I have another question.

When deciding which way to mount the subs on the baffle does it matter which way the cones are facing to get a certain sound? Or is this pretty much based on installation cosmetics & space constraints?

[simon5]

Well it depends on the crossover frequency, if you want them to play midbass and higher, they could sound better firing at the driver position, but if it's only for subwoofer usage, they can fire anywhere since wavelength is so long it doesn't matter.

[fish]

Yeah, I doubt I'd ever leave the lowpass any higher than 80hz for any significant amount of time (63hz in reality) except to experiment with them, since they are such a rare subwoofer compared to what else is out there.

I'm looking for amp options & am a bit confused. I'd like to go with 2 JL HD 600/4's to power my entire system for functionality, electrical, & stealth purposes. One amp bridged to the SLS8 midbasses, & the other to the Fountek FR88 fullranges & the 2 IB15A's. With the 600/4 for the IB15's, should I bridge the 2 channels mono, or wire it in stereo? Are there any advantages/disadvantages to running subs in stereo over mono?

Also, if you don't think 150 watts/sub is enough I have a PDX1.1000 I could use too.

[simon5]

Well, unless the sound engineer of the particular track you are listening to had a brainfart and restricted bass under 80 Hz to a single channel, there's no problem in going Stereo.

If you ask me, it's more reliable to run channels independantly than bridging with most amplifiers. You have more headroom and less distortion often also.

I don't know your listening habits, but dual IB15A with 150W to each will be quite loud. I'd expect a good ~125 dB... to me it would be more than enough, but only you know what you like. Sending 1000W instead of 300W would get you in the 130s. That is my rough estimations, your mileage may vary !

[fish]

I've never associated SPL #'s with how loud a system is, so I'm not really sure what to compare 125db's to . From what I've read from some of your posts regarding your preference for music to be on the louder side, & us having the same taste in some genres of music, I'll take your word for 125db's being "loud enough".

[simon5]

Problem is, our hearing is not sensitive much to bass signals under 80 Hz, so we often like it very loud. I honestly think it will be enough for a car audio system, if it doesn't work you can still swap your bigger amplifier. On the other hand, some people like their car audio so loud that their cars disintegrate, so it depends.

Starting at 120 dB @ 1 kHz , you get short term hearing loss, can get permanent hearing loss and shouldn't listen at that loudness for more than a few minutes a day to keep your hearing mostly intact. At 130 dB @ 1 kHz, it's the threshold of pain. Heavy metal concerts are often said to be 110-120 dB SPL average... but as I said this is at 1 kHz...

My estimations were with reasonable gain figures due to the small room your subwoofer will play into. If your car is kinda well made, well insonorized, not too leaky, it could be much louder even... you should get peaks of 140+ dB at certain frequencies that might need some EQ.

[fish]

I asked this question in my first post & it was answered by chloesdad. I just want to verify if the 300 watt power handling is a typo on the IB15A since the 10 & 12 is rated at 500 watts?

[simon5]

Yes I think it's a typo, will try to get an official confirmation.

[fish]

Any confirmation yet Simon?

Also, what size voice coil is used?

[simon5]

It's a 2 inches coil, everything is 2 inches except TD18H+ and AV line which are 2.5 inches.