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[Tim McCulloch]

So this weekend I used it on the louder rock band in a local bar/restaurant. Mmmm...... bit disappointed. 
It might have helped a bit if I could have placed it by a wall but it was a good 6 ft away from a thin partition wall.
I was having to push it hard to get decent levels and it left me wanting.

The sub didn't change, the room did.  The changed room also dictated a placement that is pretty much guaranteed to create problems.  Think in wavelengths, specifically when a reflection is 180° late in phase and what happens when that meets the un-reflected sound.

At 100Hz, the physical wavelength is 11.3ft; at 80Hz - 14.13ft; at 60Hz - 18.8ft; at 50Hz - 22.6ft. 

That you boosted EQ but could not hear a difference equal to the electrical change applied is a big clue that the problem lies in time (distance), and not magnitude.

When you grok this concept, I will have hopefully changed your (audio) life.  Time, what a concept!

You're welcome.  Please drive through.

edit ps:  I used your sig line today while talking to an artist.  He was amused.  Thanks.

[Debbie Dunkley]

The sub didn't change, the room did.  The changed room also dictated a placement that is pretty much guaranteed to create problems.  Think in wavelengths, specifically when a reflection is 180° late in phase and what happens when that meets the un-reflected sound.

At 100Hz, the physical wavelength is 11.3ft; at 80Hz - 14.13ft; at 60Hz - 18.8ft; at 50Hz - 22.6ft. 

That you boosted EQ but could not hear a difference equal to the electrical change applied is a big clue that the problem lies in time (distance), and not magnitude.

When you grok this concept, I will have hopefully changed your (audio) life.  Time, what a concept!

You're welcome.  Please drive through.

edit ps:  I used your sig line today while talking to an artist.  He was amused.  Thanks.

ha ha...you are welcome...rather funny isn't it???

You are such a  clever fella 'bout this stuff and I love to learn so I will read your response 17 times and hopefully I'll understand 50% of it !!!!

[Tim McCulloch]

ha ha...you are welcome...rather funny isn't it???

You are such a  clever fella 'bout this stuff and I love to learn so I will read your response 17 times and hopefully I'll understand 50% of it !!!!

I took my first Smaart class 10 years ago and consider myself to still be a student of time.  I can measure it, manipulate it, and sometimes do good with those.  But thinking of how time works has fundamentally changed how I think about acoustic signals.

[Jay Barracato]

I took my first Smaart class 10 years ago and consider myself to still be a student of time.  I can measure it, manipulate it, and sometimes do good with those.  But thinking of how time works has fundamentally changed how I think about acoustic signals.

We don't hear about it a lot even among those of us that overly geek out measuring. ( "I know eventually we will have a show, but I am having fun NOW", Jay said to the band waiting to soundcheck) but this type of negative information is useful to me in my decision making process. If I can't hear the result of system changes I want to know why.

One of the best things you can do with a portable system is to take the time to simply push the subs around and pay attention to how they respond to their locations. Over time placement will become a little more second nature and you will be able to look at the actual options a room offers and choose which you like best. Also take the time to walk around the room and listen for changes in the pattern.

And then once you think you have it down, some room will surprise you and then you start over with a little deeper understanding.

You can also play around in one of the modeling programs but at some point you need to relate the images to what you can actually hear.

[Debbie Dunkley]

The sub didn't change, the room did.  The changed room also dictated a placement that is pretty much guaranteed to create problems.  Think in wavelengths, specifically when a reflection is 180° late in phase and what happens when that meets the un-reflected sound.

Hey Tim....just wanted to say you were right about the room.....used the sub many times since and it has been fantastic every time....

[Jerome Malsack]

Another way to work a sub and room is what home theater teachs.   To place the sub at the listening seat and walk the room for the sound.  Then place the sub in the place where you find your sound.   

Another one is take advantage of the corner of the room to get your six to twelve db boost from the corner

[Jerome Malsack]

Another thought on the subject of the 15 inch sub is that if you placed an 18 inch sub in the same place the measured response at that location will not change.  If you have a dip at 80 hz than that will still be the problem for a 15 and 18.   If you cannot get EQ to adjust in a frequency it is a null in the acoustics and you cannot change the room on a mobile system.   Another problem is with a mobile system you never have enough time to test the venue and get a good sound check with the band.   

[Debbie Dunkley]

I have the SRX718 and was looking for a 15" sub for smaller gigs . I ordered a pair of JBL VRX 15" subs and I really like them . They're really compact and weigh only 58 lbs . Tighter sounding and I like the 4 ohm speakers .

Nice....I am sure the VRX box is a very nice one. I wanted powered though and those VRX prices are a little out of my budget .
The PRX is 81 lbs which is of course a lot heavier than the VRX box but it does balance nicely when carried since JBL moved the side handles with the PRX700 range.
I use the PRX718xlf along with 2 x PRX612's  when I don't want to take / don't have room for  my amp rack and I can also use it aux send to add to my SRX system as I did this weekend. Maybe one day Ill come across a good deal on a couple 15" subs worth getting and pull the trigger.....

[Jon C Thomas]

Nice....I am sure the VRX box is a very nice one. I wanted powered though and those VRX prices are a little out of my budget .
The PRX is 81 lbs which is of course a lot heavier than the VRX box but it does balance nicely when carried since JBL moved the side handles with the PRX700 range.
I use the PRX718xlf along with 2 x PRX612's  when I don't want to take / don't have room for  my amp rack and I can also use it aux send to add to my SRX system as I did this weekend. Maybe one day Ill come across a good deal on a couple 15" subs worth getting and pull the trigger.....

The new PRX 715 xlf is 56lbs, if you don't need extended low end the larger 18" has (35-44hz) it looks like it may offer a good compact solution.   

[Debbie Dunkley]

The new PRX 715 xlf is 56lbs, if you don't need extended low end the larger 18" has (35-44hz) it looks like it may offer a good compact solution.

That is exactly the type of sub  I what I was looking for if you check out my first post in this thread.
As things went along, I talked myself out of the 15" as I wasn't convinced it would be what I was looking for and more people had experience with the old PRX618xlf with great results.
I use the 18" as a single and it is quite capable in the smaller bars and venues and yes- it does have that nice low end...
But...yes....I would still like to hear a PRX715 xlf and compare it to the 718.  One of the nice things about getting 2 of the 15" would be  that each one is kinder to the back even though the 2 together weigh more than the one 718 of course...

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