Why are most cabs that are ported tuned absurdly high?

[ibanezcollector]

Ok I am a amatuer speaker builder and have been for quite some time. Now this bothers the hell out of me that these bass cabs are tuned as high as they are.

I did some research on my Warwick 411Pro, a Friends SWR workingmans 4x10 both are tuned high. My Warwick is tuned to 50hz which is just absurd since a good portion of the E string resides in the 40hz area which is going to make the speaker unload and become a Floopy woofing machine which it is..

The warwicks specs are -3db 50hz to 15k with a -10db roll off at 40hz right where the E string resides.

The SWR was also tuned in the 48-49hz range.

Now like I said if anyone knows anything about ported boxes will know that if the speaker goes below the freq the box is tuned at there is going to be unloading. Now considering like I said E, F, F#, G, G#, and A are under the 50hz range those notes are going to unload the speaker and make it unstable. If your using a 5 or 6 string that low B will dip down to the 30-32hz range really making the cab unusable and sloppy.

Well tonight I plan on going to my friends woodshop and making a couple of prototype boxes.


The first I idea I am going to try is the following im going to take two of the four tens and put them in a sealed box with the tweeter to produce a more accurate sound with better low mid response and smoother high mid end, the other two will be dropped into a new ported cab tuned to 28hz roughly which will allow me extended bass with power and kick ya in the kidneys feel.We have mapped a few tests in various software which is going to allow us to play these 2x10s pretty flat down to around 32hz.

The next phase were going to try after this one is a 8x10 for my friend since he uses (2) Workingman 4x10s and 6 string.

Stay tuned..

 

[CrackBass]

if only it was that easy.

 

[KJung]

IMO and IME this 'high tuning' is for a variety of reasons:

1) For many gigging situations, a deep, extended low end turns to boomy mush in a large room.

2) Usually, you want a bass guitar to sit above the bass drum in a mix, and again, that extended low end can get in the way.

3) Reproducing the fundamental of a B string, or even an E string, is not necessary for a good full, tight low end tone , and the second fundamental (if I have that right) is the key to a modern, punchy bass tone.

4) Tuning a cab very low results in that cab needing a lot of power to reproduce those very low notes. Even though power has become quite cheap today, it's not free, and it typically weighs a lot.

Interestingly, the few cabs that are tuned very low, like the Acme's, are many times used with a hi pass filter set at 50hz to 'tighten them up'.

This, IMO and IME, is an example of why technical spec's that seem to make sense don't necessarily translate into great live sound in the 'real' world.

This is IMO and IME in a big way, but, as I always say, even with these backline rigs that don't go as low as you would think they would have to, it's MUCH more common for me to walk away from a bassist in a club with no front of house support thinking 'man, I wish he had more mid definition and clarity', versus thinking 'boy, I wish that bassist had more bottom'

Edit: One additional point... extreme low end extension combined with a small box seems to result in beautiful tone that disappears about 10 feet away from the box!

 

[ibanezcollector]

KJung very good points. But take this Warwick cab for instance it doesnt lack bottom end it unloads the speaker and makes it woof.. Something that a 4 string shouldnt have to worry about I can see a 5 or 6'er running into the problem.

Also by adding the sealed enclosure I will be getting the clarity and smoother freq range only a sealed box can deliver. You lose alot of that clarity once the box is ported.

So all in all, its going to cost me $30 and some time to try a few things out. For the sake of this prototype I will be using 3" or 4" Aeroports which will give me all the port area I need to keep turbulance at bay and also the luxury of trying different port freq's.

I just cant justify having a 4x10 that will not produce the first 5 notes of my bass cleanly even flat on the pre and bass.

 

[CrackBass]

producing the low e well and playing flat down to 32hz are two different things entirely. check out acme speakers and read what people have to say about them. he makes probably the lowest 2x10 in production, and his speakers have an f3 of 42hz. they also contain a mid driver to compensate for the lack of mids due to the low excursion of the 10's. and they are inefficient. there is no way around physics. to build something that will produce 30hz with any volume you have to go big. check out billfitzmaurice.com.

 

[HolmeBass]

IMO and IME this 'high tuning' is for a variety of reasons:

3) Reproducing the fundamental of a B string, or even an E string, is not necessary for a good full, tight low end tone , and the second fundamental (if I have that right) is the key to a modern, punchy bass tone.

First harmonic is what you are talking about- the harmonic one octave above the fundamental. I agree that this harmonic is a crucial defining element of electric bass tone, modern or not.

 

[alexclaber]

Interesting stuff, keep us posted.

Bear in mind that the lower you tune your cab the more excursion your speakers need to handle the high power demands in the 60-80Hz area. Furthermore most bass cabs are so small that the excursion (and thus bass response) is restricted which helps minimise problems below the port tuning frequency. Also few bass amps have flat response - I've now seen plots of Markbass and GK heads both demonstrating significant roll off below 100Hz reducing demands on the cab.

If you're running a sealed enclosure and ported enclosure in the same range, what will happen when the response shifts out of phase? If you're not careful one pair of woofers could start cancelling out output from the other pair!

Alex

 

[alexclaber]

First harmonic is what you are talking about- the harmonic one octave above the fundamental. I agree that this harmonic is a crucial defining element of electric bass tone, modern or not.

Fundamental = First Harmonic
First Overtone = Second Harmonic
Second Overtone = Third Harmonic
etc...

Frequency of 2nd harmonic is twice 1st harmonic. 3rd harmonic is thrice 1st harmonic. 4th harmonic is quadruple 1st harmonic. And so on.

All these harmonic are crucial defining elements of electric bass tone - or any instrument. The relative proportions of them throughout the note envelope define the timbre of the instrument.

Alex

 

[RWP]

Your project sounds very interesting. One thing to watch out for is having port tuning near the driver Fs or the resonate frequency of the cabinet. If any two of these parameters are close you will have a huge resonance you do not want. The only ported cab I have built with a smooth curve down to 35 hz was 15 cubic feet in volume driven with an 18" EV driver.

 

[billfitzmaurice]

Well tonight I plan on going to my friends woodshop and making a couple of prototype boxes.
..

Instead of wasting a lot of time and plywood do some simulations of various tunings and alignments and you'll be able to see exactly what your efforts might actually gain you. The results will be very revealing, especially if you do so in WinISD Alpha Pro, which allows you to see excursion. It does not immediately spike below fb, and it's far less in the 40-60Hz range with a vented cab than with a sealed. BTW, 50 Hz is the standard tuning because that achieves a reasonable balance between extension, sensitivity, and excursion, especially above 50 Hz, as that's where the greatest power demand lies.

 

[HolmeBass]

Fundamental = First Harmonic
First Overtone = Second Harmonic
Second Overtone = Third Harmonic
etc...

Frequency of 2nd harmonic is twice 1st harmonic. 3rd harmonic is thrice 1st harmonic. 4th harmonic is quadruple 1st harmonic. And so on.

All these harmonic are crucial defining elements of electric bass tone - or any instrument. The relative proportions of them throughout the note envelope define the timbre of the instrument.

Alex

From the Wiki [Invalid or Expired Link Removed]) :

"Harmonic numbering. In most contexts, the fundamental vibration of an oscillating body represents its first harmonic. However, some musicians, tuners, and even developers of piano tuning software do not consider the fundamental to be a harmonic; it is just the fundamental. For them, the harmonic one octave above the fundamental (the second mode of vibration) is the first harmonic or first partial. There are logical arguments for both approaches to numbering, but in this article, the fundamental vibration is referred to as the first harmonic for simplicity and consistency with the important notion of odd and even harmonics."

So perhaps you are *more* correct, but I am not alone in the terminology I used.

 

[billfitzmaurice]

From the Wiki [Invalid or Expired Link Removed]) :

"Harmonic numbering. In most contexts, the fundamental vibration of an oscillating body represents its first harmonic. However, some musicians, tuners, and even developers of piano tuning software do not consider the fundamental to be a harmonic; it is just the fundamental. For them, the harmonic one octave above the fundamental (the second mode of vibration) is the first harmonic or first partial. There are logical arguments for both approaches to numbering, but in this article, the fundamental vibration is referred to as the first harmonic for simplicity and consistency with the important notion of odd and even harmonics."

So perhaps you are *more* correct, but I am not alone in the terminology I used.

F=H1. You say tomato, I say tomahto.

 

[HolmeBass]

Exactly my point. I guess in this case I am in the "tahmato" crowd.

 

[MuzikMan]

FWIW I don't think there's a lot going on below 60hz even on the lower strings of most electric basses. When I ran my bass into Sound Forge it showed that my fundamental was the strongest until about low A then the second harmonic started dominating as I played lower.

I have also had bad experiences with the PA by running too many lows on stage.

IMO the way to strong bass is an F3 of about 50hz with good excursion capabilities. This keeps harmonic distortion low which cleans up the low-mids.

Now, if we're talking home theater then it's a whole other ball o' wax.

 

[fdeck]

I think it's a matter of tradeoffs. A speaker has a power dip on both sides of the port resonance. Increased power handling on one side of the dip is at the expense of the other. The prudent designer puts the port tuning where it needs to be, based on their understanding of the actual bass waveform, which is not a pure sine wave. This is guided by both theory and experience working with bassists.

Tuning down to 30 Hz will expose a huge power dip above 30 Hz. I don't think this is a solution. The only solutions obey "small, loud, low." For that reason, I think that if a speaker is farting out before reaching the volume level that you desire, you may need more speakers.

 

[ibanezcollector]

the cab is farting out at bedroom levels.. Not a good thing.. Subs are fine checked them nothing binding the coils, free movement, no scratching with movement etc. Good Re measurements..

There is no reason this cab should fart out..

Boxes are built just need to do some sealing internally, and then testing tommorrow.

We shall see worst case scenario is $25 lost and some time

 

[bgavin]

One thing to watch out for is having port tuning near the driver Fs or the resonate frequency of the cabinet. If any two of these parameters are close you will have a huge resonance you do not want.

This is entirely inaccurate.

First, Fb=Fs is the SBB4 alignment, which is the tightest and least boomy of all the vented alignments. The port tuning is the resonant cabinet frequency, so they are always the same.

Next, there are two resonance points in a vented cabinet. The higher Fh is the one responsible for boom. This occurs when an acoustically large driver is stuffed into a too-small cabinet volume. This is typical of most commercial boxes, and most pronounced with 15" drivers. One example is the Eden mid-bass hump in the D410XLT series. Vented cabs designed for the driver's T/S parameters do not boom.

As noted above, the tuning point does indeed influence cone excursion exceeding Xmax. Different vented alignments have different cone excursion characteristics. It varies by driver/cabinet combination.

For the original poster, going into the woodshop without a plan, is the same as getting into your car and just driving, and hoping you wind up somewhere "good". Your prototype might not totally suck, but it would be so much better if you had a well thought out plan. There is a huge wealth of free information and tools available to you. Use them; have a good result.

 

[bgavin]

FWIW I don't think there's a lot going on below 60hz even on the lower strings of most electric basses.

My signal analysis of my four basses (2 P, J, L1500) show the fundamental amplitude almost identical to the 2nd harmonic at the time of attack. The fundamental decays much more rapidly, but it is indeed present at the attack. Analysis software averages over time. Your ear hears the entire signal, including attack and decay.

The easy way to determine this is with a 31-band graphic equalizer driving a full range speaker system, such as a premium HiFi set: Drop all sliders below 60 Hz to zero, and see if you like the tone. If you get no change, then your bass isn't producing anything audible in the fundamentals.

However, if the tone is thin and drooping, you are cutting out the meat below the 60 Hz line. If you like your meat trimmed, that is fine; taste is subjective. If you don't like a thin tone, then use a cab that produces more fundamental.

 

[Stumpy]

IMHO you should have looked at the Eden stuff before you went off on this venture...or not...

JBL put out a one page list for tuning enclosures as well as the other specs needed to build appropriate cabs.

Look at the Eden D210XST. It is tuned to 30hz and it has 2
10" speakers. So, it is fast and low.

I bought the cab because of the low tuning ... for my B string. I haven't regretted it at all.

 

[ibanezcollector]

For the original poster, going into the woodshop without a plan, is the same as getting into your car and just driving, and hoping you wind up somewhere "good". Your prototype might not totally suck, but it would be so much better if you had a well thought out plan. There is a huge wealth of free information and tools available to you. Use them; have a good result.

I did not go in there and just randomly build a box of any dimension..

I stated at first that I am a amatuer speaker builder. My home stuff gets rave reviews by many who have had the chance to audition them.

I have been designing speakers for about 8 years. So this isnt my first attempt at designing a box. I did plan this out for almost 3 weeks.

Today I get to audition them, and will take some pics when I bring them home. If they come out as designed and sound the way I like them then I will be making them out of 11ply voidless birch.