front or rear ported cabs.....opinions

[Dan Dare]

[quote name='Bill Fitzmaurice' timestamp='1504712448' post='3366832']
Watch this, particularly from the 1:00 marker to the 5:10 marker, although almost every member here would benefit from watching all of it:

[media]http://www.youtube.com/watch?v=BYTlN6wjcvQ[/media]
[/quote]

I enjoyed that film you posted, Bill. The first 5 minutes that you recommended are a perfect example of confirmation bias in action. None of us is immune from it.

[fftc]

[quote name='Bill Fitzmaurice' timestamp='1504726961' post='3366961']
The science of audio always works, whether you believe in it or not.
[/quote]

[Kevin Dean]

[quote name='fftc' timestamp='1504768473' post='3367105']

[/quote] But He doesn't have this problem with my front ported cabs , To me it's obvious that the low end would also be louder to him with the rear port .

[Ghost_Bass]

I've had the same experience as Kevin with my drummer but with cabs standing on his side. With one cab (Aguilar GS112T) i had to rotate my rig so it would point a bit to him to allow him to hear some note definition.

[quote name='Phil Starr' timestamp='1504721595' post='3366908']
The trouble is you are comparing chalk and cheese.

You aren't comparing speaker cabs with the same drivers in, they aren't the same shape, size and the ports are all different sizes and shapes. In addition unless you did your testing all in the same room with the speakers carefully placed at the same spot using the same bass and amp with the settings all identical it isn't really a fair test. Oh, and you'd have to put the speakers behind a screen and the assistant switching the speakers round wouldn't have to know which was which either, a double blind test.

What I'm hearing is that you prefer some forward ported cabs to some rear ported cabs. You are probably right but that isn't necessarily about the port. Most of us prefer the look of a traditionally ported cab (me included) they just look right. The reasons for putting the port on the back are usually to do with the restricted size of modern cabs.
(...)
[/quote]

I like a modern, flat EQ, sound. My bass is full range, i don't touch the EQ on it and the amp, amp isn't coloured also. I think the fairest comparisson between cabs i can make is the Genz Benz STL-12T and the Barefaced Midget-T, both have similar specs, similar drivers, modern, and uncoloured. Amp is the GB STL9.2, it has a built-in HPF so both cabs handled the same low freqs. GB cab was muddier on stage, drummer kept asking me to cut lows. BF cab was tonal heaven for him.
For me, with the GB cab i had to turn it up a notch to feel a bit of mid-bass punch whilst trying to cut down the boomy sub-lows. BF cab was straight up flat with plenty of punch and definition.

[quote name='Bill Fitzmaurice' timestamp='1504726961' post='3366961']
(...)
The science of audio always works, whether you believe in it or not.
(...)
[/quote]

Math is true and universal, i know that, i'm an engineer. The Science of Sound is true also but in your proofs and charts and freq response curves you're showing me how a cab behave in an ideal and controled situation, you're not taking in account where i play and how the stage is layed out. My rig isn't for FOH, i'm fully aware thay if i moved to the center of the room i wouldn't hear diference from front or back port but i'm standing there, 1 to 2m in front of the rig, drummer at the same distance on it's side, sometimes a wall 1m or less behind the rig... it all adds up! That's why i (again) say that FOR ME i don't want any more rear ported cabs and I DO can tell a diference in the sound on stage between both configurations.

Cheers

[Bill Fitzmaurice]

[quote name='Kevin Dean' timestamp='1504770251' post='3367123']
But He doesn't have this problem with my front ported cabs , To me it's obvious that the low end would also be louder to him with the rear port .
[/quote]And again, the science is never wrong. As I already noted the main reason why some cabs are rear ported is that they're too small for the ports to fit on the front. Smaller cabs have higher Q than larger cabs, resulting in boomy response, and that's why what he hears with front versus rear ported cabs is different, not the port location. The difference will be less obvious to you, as the boom is masked by the mids and highs that you can hear because you're in front of the cab, and he can't, because he's behind it.

[alexclaber]

[quote name='Ghost_Bass' timestamp='1504777984' post='3367214'] I think the fairest comparisson between cabs i can make is the Genz Benz STL-12T and the Barefaced Midget-T, both have similar specs, similar drivers...[/quote]

The only thing similar about those drivers is the nominal diameter. Seriously, they could barely be more different! And the difference between them in the cabs they're in explains the different your drummer was hearing, which is nothing to do with the port location.

[Phil Starr]

This sort of discussion goes one of two ways usually. Somebody like the OP raises a question and a few people chip in with observations then the techies get involved and try and explain the observations. Sometimes they (we?) agree completely and sometimes they don't, differing on details or perhaps interpretation. Science will tell you a lot about what a particular speaker in a particular box will sound like but it has nothing to say about which sound you will prefer.

What we all hope is that by sharing some of the technical stuff people learn a little about how the gear' we all use works and can use their understanding to shorten their search for their sound, and at the same time stops them wasting money because they can't see through the advertisers hype.

If you re frame this thread someone is saying 'I think I can hear a difference between front ported and rear ported cabs' and is asking if there is any technical explanation. Bill has put up a graphic showing that bass at very low frequencies is radiated equally in all directions and you can verify this yourselves with any textbook or a quick search of the internet.

Then both Bill and I have explained that for the most part ports are put on the rear because of space considerations in very small cabs and that in turn is down to the nature of the speakers used to drive the cabs. This is all down to something which I called damping and Bill called Q, the mathematical symbol for the damping of tuned systems. Well damped speaker cabs are usually powered by speakers with more powerful magnets and are built into smaller boxes, poorly damped speakers tend to be built into larger boxes which will have more space for the port to be on the front.

Now the damping affects the frequency response at the bottom end in a predictable way. Poorly damped speakers have a typical bass boost around the 100Hz range that typically is described as 'punch' well damped speakers have the cone movement, well damped really, so they have a flatter response which even droops slightly if they are over-damped. So well damped speakers are less likely to have a bass hump and more likely to be in small cabs with the port at the back and under damped 'punchy' speakers are more likely to be bigger speakers and have front ports. But, you can design front ported speakers that are well damped and put the ports in the back of underdamped speakers. There may be a small correlation with what Ghost Bass is experiencing but the causal link is the damping of the speaker and as Alex has said his well damped drivers are going to have little in common with the Genz-Benz.

Of course well damped and poorly damped are only the way we describe the Q of the speaker in words. You may prefer added punch in your speaker (I do) so an underdamped design may be what you are looking for, it may even sound more natural to you as most bass speakers are underdamped designs. So the advice is still the same, don't worry about the ports and use your ears.