Help me understand "off-axis response" and why my rig sounds bad in certain areas

[bovine mind]

Every rig I've played on sounds decent to great directly in front of the cabinets, and not so great the further to the left or right I move from the center.

Even now that I've attained my 98% complete dream rig, I still suffer from marginal results when I'm moving around the stage or rehearsal space and not standing directly in front of the speakers.

My current rig is a Sunn 215BH + Ampeg 810E + Sunn 1200s rack amp with a Gibson ripper drop tuned to CGCG.

I'm using mismatched driver sizes, so I am probably suffering some effects of speaker phase, but I recall hearing the same detirment to tone when I was using just the Ampeg 810E.

The tone I hear when I'm standing diagonally from the edge of the cabs is a very midrange focused, honky, carboard sound with minimal low end and more apparent fret/pick noise. when I'm standing right in front, or even almost behind the cabs where my drummer is, the tone is incredible, overhwelming, vision blurring, lower back and stomach thumping low end with creamy low mids and crystaline highs, while moderately overdriven.

Is this problem pretty much unavoidable given cabs in a similar price range? What do the terms "off-axis" and "speaker phase cancellation" have to do with what I'm hearing, in practical laymens terms?

Lastly, do speaker phase issues when using mismatched driver sizes have an effect on infinite sustain? In some parts of the room I can't get notes to sustain as long as I'd like, even with a fresh setup.

Thanks for insight.

[KJung]

You are over thinking things. The phase issue is minor... don't worry about your 'mismatched cabs'.

What you are hearing is typical of any cab. Mids are directional, low end is not. So, when you are off to one side of the cab (when close up on stage), you hear more low end (i.e., below 700 hz or so), since that radiates from a cab in all directions. The upper mids are more directional. Of course, once you get 30' out in front of the cab, everything balances out nicely again.

Using smaller drivers (which beam midrange less) and using a pure vertical stack (i.e., one speaker on top of one another... I'm talking single drivers, not cabs) will slightly reduce this issue, but not much with the bass guitar, since again, the issue is relatively minor unless you are very close to your cab.

Interestingly, most feel the exact opposite as you do when standing to the extreme side of a cab relatively close to it... too much low end, not enough midrange. If you want that sound when you are in front of your cab.... turn the mids down That's an easy one!

K

[JimmyM]

beaming is what it's called. the larger the speaker, the more the highs and mids will focus to a narrower area of dispersion. that's why mid drivers in pa's are either horns or cones in the 6-8" range, and tweeters are even smaller...because the smaller speakers have better dispersion of those freqs.

beaming is compounded when you have drivers arranged in a row...like for example, an 810 will have the mid/high dispersion characteristics of a 21" speaker because there's two 10"s in a row with an inch between them (give or take). so if you have an 810 and a 215 next to each other, they will have the beaming characteristics of a 36" speaker.

one thing you can do to increase dispersion out to the crowd is take each cab and angle them at 45 degree angles facing each other, like this:

/ \

it's possible you are also getting phasing, but since i haven't heard it (and quite frankly couldn't take it for one second), i don't know. i do, however, know that you'll get beaming. for me it's not a problem since i almost always have a pa to run it through. you don't have that luxury, so try the angled cabs next time.

[bovine mind]

Originally Posted by KJung

You are over thinking things. The phase issue is minor... don't worry about your 'mismatched cabs'.

What you are hearing is typical of any cab. Mids are directional, low end is not. So, when you are off to one side of the cab (when close up on stage), you hear more low end (i.e., below 700 hz or so), since that radiates from a cab in all directions. The upper mids are more directional. Of course, once you get 30' out in front of the cab, everything balances out nicely again.

Using smaller drivers (which beam midrange less) and using a pure vertical stack (i.e., one speaker on top of one another... I'm talking single drivers, not cabs) will slightly reduce this issue, but not much with the bass guitar, since again, the issue is relatively minor unless you are very close to your cab.

Interestingly, most feel the exact opposite as you do when standing to the extreme side of a cab relatively close to it... too much low end, not enough midrange. If you want that sound when you are in front of your cab.... turn the mids down That's an easy one!

K

I'm sure I'm overthinking things. Having ample free time at a desk job + neurotic personality + having some extra cash to improve my rig if I can = overthinking.

Glad to hear this problem isn't just in my head, and that it is a common somewhat unavoidable experience without a PA to even out the sound in the house, where the audience will hear most of my tone. The problem is I play a lot of smaller venues that don't mic my cabs because the soundman [and I, until I started thinking about this tonal issue] don't think it's necessary given the mammoth volume that's usually sufficient to fill the house.

Good to know how beaming works with different sized drivers. I'm thinking about swapping the 810 for a boutique 4x12 or 4x15 and stacking it on the 215 to help even things out.

[bovine mind]

Originally Posted by JimmyM

beaming is what it's called. the larger the speaker, the more the highs and mids will focus to a narrower area of dispersion. that's why mid drivers in pa's are either horns or cones in the 6-8" range, and tweeters are even smaller...because the smaller speakers have better dispersion of those freqs.

beaming is compounded when you have drivers arranged in a row...like for example, an 810 will have the mid/high dispersion characteristics of a 21" speaker because there's two 10"s in a row with an inch between them (give or take). so if you have an 810 and a 215 next to each other, they will have the beaming characteristics of a 36" speaker.

one thing you can do to increase dispersion out to the crowd is take each cab and angle them at 45 degree angles facing each other, like this:

/ \

it's possible you are also getting phasing, but since i haven't heard it (and quite frankly couldn't take it for one second), i don't know. i do, however, know that you'll get beaming. for me it's not a problem since i almost always have a pa to run it through. you don't have that luxury, so try the angled cabs next time.

/ \ <<< interesting, I'll have to try that. I appreciate the extra info on compounded beaming. The thing is, it really isn't that big of a problem when I'm playing with the rest of the band, as the emphasized mids actually sound good given the guitar, drums, and bass synthesizer filling everything in, but I guess I'm just unreasonable when it comes to wanting myself and the audience to all hear the tone that I hear when standing right in front of the cabs.

I should probably start asking the sound guys to mic my cabs with this specific request in mind.

[rpsands]

Originally Posted by bovine mind

I'm sure I'm overthinking things. Having ample free time at a desk job + neurotic personality + having some extra cash to improve my rig if I can = overthinking.

Glad to hear this problem isn't just in my head, and that it is a common somewhat unavoidable experience without a PA to even out the sound in the house, where the audience will hear most of my tone. The problem is I play a lot of smaller venues that don't mic my cabs because the soundman [and I, until I started thinking about this tonal issue] don't think it's necessary given the mammoth volume that's usually sufficient to fill the house.

Good to know how beaming works with different sized drivers. I'm thinking about swapping the 810 for a boutique 4x12 or 4x15 and stacking it on the 215 to help even things out.

A boutique cab with large drivers set side by side will do nothing to help you here.

To improve your frequency dispersion angle to the point that you hear the same things to as much as 30 degrees to either side of your cabinet, you are going to have to rethink what you know about cabinets.

There are mainly three valid approaches to achieving solid performance 30 degrees off axis:

1) Use a midrange driver of some sort crossed over below the woofer starts to beam (conservatively, 1khz for 15s, 1200hz for 12s and 1500hz for 10s. 10s can get up as high as 2khz or so off-axis, but it depends on the driver somewhat).

2) Horn load it. This is complex and I wouldn't do it except with BFM's designs, for bass.

3) Use a line array of 10s NOT SIDE BY SIDE. Imagine if you cut an 8x10 in half from top to bottom and used one side of it; that's what you want.

A line array of 12s can work but it's not as good as 10s.


Now, with those things said, if you want a single monster loud cabinet with amazing off-axis performance, the only ready designed option is the 1515/66 fEarful. It's as sensitive as a 6x10 and can shatter any 8x10 on the market in peak volume.

[KJung]

Originally Posted by rpsands

A boutique cab with large drivers set side by side will do nothing to help you here.

To improve your frequency dispersion angle to the point that you hear the same things to as much as 30 degrees to either side of your cabinet, you are going to have to rethink what you know about cabinets.

There are mainly three valid approaches to achieving solid performance 30 degrees off axis:

1) Use a midrange driver of some sort crossed over below the woofer starts to beam (conservatively, 1khz for 15s, 1200hz for 12s and 1500hz for 10s. 10s can get up as high as 2khz or so off-axis, but it depends on the driver somewhat).

2) Horn load it. This is complex and I wouldn't do it except with BFM's designs, for bass.

3) Use a line array of 10s NOT SIDE BY SIDE. Imagine if you cut an 8x10 in half from top to bottom and used one side of it; that's what you want.

A line array of 12s can work but it's not as good as 10s.


Now, with those things said, if you want a single monster loud cabinet with amazing off-axis performance, the only ready designed option is the 1515/66 fEarful. It's as sensitive as a 6x10 and can shatter any 8x10 on the market in peak volume.

Reread his post... he doesn't want his off-axis tone to sound like his 'on axis' tone, but rather wants his cab to sound like it does off axis all the time.

Simple as pie... turn the mids down, or get a less midrange voiced cab.

If he felt the opposite, then your comments would be valid.

[JimmyM]

Originally Posted by KJung

Reread his post... he doesn't want his off-axis tone to sound like his 'on axis' tone, but rather wants his cab to sound like it does off axis all the time.

Simple as pie... turn the mids down, or get a less midrange voiced cab.

If he felt the opposite, then your comments would be valid.

funny, but i thought he liked the sound in front of the cab and not off to the side.

[aborgman]

Originally Posted by KJung

Reread his post... he doesn't want his off-axis tone to sound like his 'on axis' tone, but rather wants his cab to sound like it does off axis all the time.

Umm... no.

The tone I hear when I'm standing diagonally from the edge of the cabs is a very midrange focused, honky, carboard sound with minimal low end and more apparent fret/pick noise. when I'm standing right in front, or even almost behind the cabs where my drummer is, the tone is incredible, overhwelming, vision blurring, lower back and stomach thumping low end with creamy low mids and crystaline highs, while moderately overdriven.

He describes the off-axis sound as:

"very midrange focused, honky, carboard sound with minimal low end"

He describes the on-axis sound as:

"incredible, overhwelming, vision blurring, lower back and stomach thumping low end with creamy low mids and crystaline highs, while moderately overdriven"

That sure sounds like he likes the on-axis sound more to me.

[rpsands]

I can't say why the off-axis sound is backwards from what it should be. That's the only puzzler here. It's impossible to make lows directional in a direct-radiator cabinet from what I understand.

My best guess is that he's losing the "thickness" of the mids off-axis and getting dustcap sounds and/or horns.

With a very wide stack - say an 8x10 layed on its side, or a 2x15 laid on its side) it is possible to get directionality down around 300-400hz AFAIK.

If his off-axis signal was lossy from 400hz to where either a horn or dustcap radiation kicked in, I could see that making a very honky tone. 400hz is a lot of meat of the bass signal.

I don't know exactly how the upper mid radiation pattern of a direct radiating cab works but I recall reading at one point that the dustcap CAN provide a bit of gain off-axis in the upper mids.

Just throwing out guesses here.

[Buzz Grim]

Originally Posted by bovine mind

Every rig I've played on sounds decent to great directly in front of the cabinets, and not so great the further to the left or right I move from the center.
...I still suffer from marginal results when I'm moving around the stage or rehearsal space and not standing directly in front of the speakers.
..... The tone I hear when I'm standing diagonally from the edge of the cabs is a very midrange focused, honky, carboard sound with minimal low end and more apparent fret/pick noise. when I'm standing right in front, or even almost behind the cabs where my drummer is, the tone is incredible, overhwelming, vision blurring, lower back and stomach thumping low end with creamy low mids and crystaline highs, while moderately overdriven.

It sure sounds like he wants the on axis, standing in front of the cabinet, sound to me.

[bovine mind]

Yeah, to clarify:

Tone in front of cab = good = on-axis

Tone at diagonal angles = bad = off axis

Want: tone at angles to be equal to tone in front.

Probably not going to happen unless I pester the soundguy to mic my cabs and mix this desired tone into the house. Don't have any time or supplies to devote to building a Fearful cab so my options are limited to what is out in the market, and also influenced by aesthetic and price. Partial to the Emperor and Electric Amp cabs right now.

I could try turning the mids down I suppose. I have enough power and volume to get away with it and still be heard in the band.

[synaesthesia]

Originally Posted by KJung

What you are hearing is typical of any cab. Mids are directional, low end is not. So, when you are off to one side of the cab (when close up on stage), you hear more low end (i.e., below 700 hz or so), since that radiates from a cab in all directions.
K

Bass cab frequencies are generally omnidirectional below 100 hz depending on the size of the cab; above that it is directional. At 700 hz, it is definitely directional.

[billfitzmaurice]

Originally Posted by bovine mind

Glad to hear this problem isn't just in my head, and that it is a common somewhat unavoidable experience without a PA to even out the sound in the house, where the audience will hear most of my tone.

It's 100% avoidable. Use smaller drivers with wider dispersion for the highs, and keep all the drivers that operate in the same bandwidth vertical. Finding cabs that are built that way is the tough part, few are.

[KJung]

Originally Posted by rpsands

I can't say why the off-axis sound is backwards from what it should be. That's the only puzzler here.

That's what mixed me up also... just the opposite of what you would think. He described the typical on-axis tone when he was standing off axis, and equated the 'in front of the cab / on axis' sound to being behind the cab, which would be all low end.

I'm still thinking it is just the mid voicing of that sealed 810 that is the issue. A more deeply voiced and less mid present cab would most likely solve his issues.

[rpsands]

FEarful cabs do not have to be built yourself, entirely

1- Swift makes a cutcut which requires gluing, clamping and finishing.

2- There are a number of builders who will do them for you completely (LDS, and a number of other folks)

Another option is Speakerhardware.com's BFM cabs (If I wanted a full range system and didn't mind hauling, I'd get an OT12 and a Titan 48 or something along those lines).

[KJung]

Originally Posted by synaesthesia

Bass cab frequencies are generally omnidirectional below 100 hz depending on the size of the cab; above that it is directional. At 700 hz, it is definitely directional.

+1

[rpsands]

Originally Posted by synaesthesia

Bass cab frequencies are generally omnidirectional below 100 hz depending on the size of the cab; above that it is directional. At 700 hz, it is definitely directional.

This is something that gets glossed over very often in the "on axis vs. off axis."

Generally speaking, all bass cabs are directional starting from something like 100-200hz, with reducing dispersion angle as the frequency climbs.

The point at when the dispersion is unintelligible is typically when it's worse than 6db at 30 degrees off-axis, but if you go further than 30 degrees off-axis it tends to be WAY worse and way faster. Say you stand right next to your cabinet you're 90 degrees off axis or more.

You want to, generally, be within that 60 degree front arc of your cabinet, or 90 degrees if you have a really well designed cabinet. That means no worse than 30-45 degrees off-axis.


EDIT: This is why high end PA cabinets offer something called a POLAR RESPONSE CHART that shows you how this looks. IMHO, all bass cabinets above the bargain basement should have this measurement done.

[bovine mind]

Originally Posted by KJung

That's what mixed me up also... just the opposite of what you would think. He described the typical on-axis tone when he was standing off axis, and equated the 'in front of the cab / on axis' sound to being behind the cab, which would be all low end.

I'm still thinking it is just the mid voicing of that sealed 810 that is the issue. A more deeply voiced and less mid present cab would most likely solve his issues.

Behind the cab is all low end, near where my drummer is. Sounds great , for some of our songs that are more hypnotic, trancelike, and groove heavy.

But in the center of the room, which is more off-axis to my cabs, there is minimal low end, and mostly mids, which doesn't sound so good.

Part of it probably is the voicing of the 810E. When I bought it I wanted a cab that would cut through a wall of distorted guitar and had an amp that wasn't that powerful.

[savinggrace]

Can you list a few? Thank you!

Originally Posted by billfitzmaurice

It's 100% avoidable. Use smaller drivers with wider dispersion for the highs, and keep all the drivers that operate in the same bandwidth vertical. Finding cabs that are built that way is the tough part, few are.