Speaker breakup and tone

[will33]

So...plenty of stuff on here about " I need 3 million watts and 4 nautical miles of excursion to produce the 30hz output I need to best my competitors in the commercial demolition business ". Yup, that's how we get a lot of clean lows....displacement.


So, lets take a little move to the right on the chart a bit and figure out the rest. Midrange...that is afterall what gives us "tone", and a sense of pitch to our rumble.

Some speakers just happen to sound really "musical", for lack of more techy term, when you push them...especially some guitar speakers when you use them to carry the middle and high ranges of a bass.....why?

Cone mass, stiffness...dustcap composition, mass and porousness...voicecoil in relation to gap/purposely running non-linear with very little power....the magnetic field and it's focus...or lack of it.

Dragging ourselves out of the frequency basement for minute, how do these speakers act that makes them do this in the rest of the bandwidth?

I suppose you could also come at it from the other way...giving some examples of what makes a very clean, "accurate" middle range and then point out some differences that these "dirty" speakers do "wrong" that can sound so right.

What are some compromises made for single drivers to have "enough" lows but still a nice sounding breakup, without the benefit of a clean woofer carrying the bottom?

Guru's.....explanations....experiences....links?

[Mr. Foxen]

Breakup without breaking is in the difference between xmax and xlim. Guitar speakers work off breakup and have low xmax and high xlim, relatively, so they break up loads.Stiffer suspension and surround make for nasty breakup in the top, which is why guitar speakers tend to sound better after wearing in.

[will33]

Yes, the xmax/xlim relationship I understand. Also notice different suspension stiffness, etc. when toying with various drivers. Some you can shine light through the dustcap and see the polepiece, etc. (porous), others solid paper, others aluminum.

There's more to the stew though.

This stuff is becoming more interesting to me than "how to male a low frequency piston" so to speak. Becoming more interested in varying flavors of breakup and "character".....wondering what all's in the recipe. Or better said, what ingredients are in the cabinet that folks use to make all these different flavors.

[rpsands]

I have a two word answer to this question: Fuzz pedal.

[Mr. Foxen]

Liking distortion is massively subjective, so its not really something you can say 'this construction method sounds good'. The only thing you can do and have some engineering to it is check a chart for the peaks from cone breakup modes and figure where the peak you like is, I think a broader peak is less harsh on the ear too.

[JGR]

I find magnet type (alnico vs. ceramic) and weight play a big factor when you get into the guitar realm of things. Neo has come a long way, but it would be my last choice. With magnets, I like the punch, brightness, and clear grit I get from larger, high-powered ceramic magnet guitar speakers vs the ones in the 15-30watt range, generally speaking. Alnico definitely adds a lot of top end chime and complexity which is cool in certain applications - very noticeable if you play identical speakers with different magnets. Cone material, seams, and ribbing also factor into the tone profile.

The response graph tells a big part of it - a lot of the Eminence drivers for instance have a massive dip in the 1 - 1.5 kHz range which I hate. Celestions much less so. You can get an idea of the breakup modes looking at the trace and the corresponding impedance plot.

These types of drivers certainly add their own complex character, and it's not something that can be replicated with a pedal or by goosing the gain. Its one key piece of the puzzle, along with strings, pickups, setup, and amp. Hence why you don't see guitarists playing high gain through PA speakers. That said, one of my favorite speakers for guitar is the EVM12L, and while it is insanely high powered and clean, it also sounds great with high gain due to the response characterisitcs in the 1-5 kHz range which you can clearly see on the spec sheet. IME, this is one area where also being a guitar player has its advantages.

The Bag End drivers are one of my favorites that do great top end crunch and also handle the low end well (for what I like). The Berg NV412 drivers also do a pretty good job though they are much cleaner in the top end than the Bag End drivers - they remind me of the EV's but with more bottom - my NV412 with the AxeFxII and a big power amp makes for a devasting guitar rig. My 15/8's are also exceptional for bass as well as clean and distorted guitar. Clean lows, crunchy mids and highs, that's what I like.

[dhsierra1]

Originally Posted by JGR

That said, one of my favorite speakers for guitar is the EVM12L, and while it is insanely high powered and clean, it also sounds great with high gain due to the response characterisitcs in the 1-5 kHz range which you can clearly see on the spec sheet. IME, this is one area where also being a guitar player has its advantages.

+1, a fantastic guitar speaker, and so is its bigger brother the -15L. SRV used these in Vibroverbs IIRC.

Interestingly enough they also make a dynamite bass driver in the right cab (a TL606 type usually but not always). Bright but clean, different midrange character than the JBL D/K140s. The latter were alnicos, the former ceramic magnets.

It would be interesting to compare frequency response curves as well as impedence of these then take a closer look at the components and construction.

[BogeyBass]

From what i understand has a lot to do with the stiffness of the cone surround and the strength of the magnet.

stiff cone in theory more controlled, loose less control of course can effect bass response and the stiffer it is needs more magnet strength. likewise changing one effects everything else

so Qms (mechanical quality)will measure the total amount of mechanical suspension between the spider and surround and Qes (electrical quality)will show the relation between voice coil and magnet.

can go both ways loose suspension lighter magnet or stiff suspension heavy magnet, most of that relation is shown in the Qts or the overall quality of the system.

so a sealed driver will usually, not always but most the time will have lower Qts around .5 or lower and then when you get into vented or open back applications Qts can be higher around .7 or higher.

from what i can tell with guitar drivers, most of them are designed for open back operation and they all seem to have very stiff suspension or high Qms ratings. then its a matter of how much excursion or xmax you want, or how much sensitivity you want. to determine how strong the magnet is. which or course all those factors have an effect on the total displacement of the driver (Vd)
overall between the balance of the 2 guitar drivers seem to have very high Qts of .6 or higher

if you want alot of xmax then you need a stronger magnet to still have control over the cone as it starts to reach the end of the gap. likewise if you want a very sensitive speaker a strong magnet and shorter gap will do that as well. but again all the factor come into play gap, magnet strength, suspension change one effects all the others. could have high sensitivity but has upper range distortion, or less bass but smoother upper distortion

from what a heard stiff suspension can also cause more distortion in the upper range. and too much magnet strength can cause a drop in bass response.

likewise the mass of the cone, heavy cone or lighter cone or basically thicker or thinner will have effect on distortion and also Qms.
and thinner cones tend to have more upper frequency response but can have more distortion in bass response

[will33]

Nice responses so far, and kinda what I was hoping for...the inner-workings of the raw driver.

Just goofing around with drivers I have/available to me, which run from "meh" to "pretty good", I notice things like softer cone material and looser suspensions in things like guitar drivers that breakup, but it's not limited to just those. Even in 6" "PA oriented" midranges, ones that sound bad when you "make them work" with a bass feel a little stiffer when you push on them than ones that have useable "character" when you lay the power on, even in the same setup with identical active crossover points, woofers and power levels. So, that's part of it.

Many guitar drivers though share similair characteristics, yet sound way sifferent, whether actually reproducing the guitar, or carrying the mid/top of a bass, so, must be more to it.


Notice my use of magazine article descriptions here....I lack the technical knowledge to use technical terms for this part of our tone spectrum. Looking to expand my knowledge of that and thanks to you all for chiming in, providing a sort of stimulus.

[will33]

To add....I read response charts and know at least somewhat what aort of peaks and valleys I like in the mid/upper frequencies and they've proven to translate to real life sound pretty well if you stick to low power and clean tone. Add more power and start making things bwhave in some different fashion and suddenly the 1w charts don't jive....they don't tell the whole story.

Unfortunately, I lack the material and financial resources to do multiple, high power and possibly destructive tests.....mostly 1w data sheets and ears over here.

[dhsierra1]

you mean destructive speaker testing like this?

[JGR]

Originally Posted by will33

To add....I read response charts and know at least somewhat what aort of peaks and valleys I like in the mid/upper frequencies and they've proven to translate to real life sound pretty well if you stick to low power and clean tone. Add more power and start making things bwhave in some different fashion and suddenly the 1w charts don't jive....they don't tell the whole story.

Unfortunately, I lack the material and financial resources to do multiple, high power and possibly destructive tests.....mostly 1w data sheets and ears over here.

Good point regarding the dynamics at different power levels; just like with a tube amp, there's also a lot of goodness to be had with varying levels of attack.

+1 on the financials involved with experimenting; I went through three different 8's on the first design, currently on my 4th 10 with the current cab, not to mention crossover components (or the high dollar woofers I've smoked).... and that's with having a pretty good idea of what I'm looking for, but it's ultimately what separates good from great.

[jungleheat]

I think just that little bit of speaker breakup in the midrange can be good for some things. What happens is you get all those overtones going, but at the same time the peaks and troughs tend to get compressed a bit. In a rock guitar cab, you can get pretty extreme with the breakup and still have it sound "cool". For PA purposes, you want a lot less. I think the ideal is just enough THD so that there's a perceptible change, but NOT enough so that it's obvious as distortion in the sound. Maybe in the 2-5% range or so?

But then once you get past a certain range, you don't want that distortion any more (like with the low end). So for a good PA, need enough tweeters to handle the task at hand. The tweeters you want a bunch of them, all barely working at all, just enough to give that air to the sound. With subs, you want to give them enough power to work with, but when you have a ton of speaker headroom available, you just get this overall HEFT to the sound that is amazing.

My big stereo which is unfortunately decommissioned right now after a flood took out some of the electronic components consisted of 2 pairs of JBL L-100s (12 inch 3 ways), powered by a Soundstream DA-4 (with some retarded amount of headroom), and a Soundstream SPL-170 (15" sub) in a custom cab my brother designed and built that was about the size of a small fridge, driven bridged by a Sony ES amp, also with plenty of power. All that in about a 25 by 15' living room.

So that system would POUND with plenty of deep lows from the 170, great low mids from the JBL 12s, and present but not overbearing mids and clear highs from the mids and tweeters. In that system, nothing was ever overworked, because there was so much more headroom (both in watts and speaker area) than I needed for the space. So because of that, when I would get it going a little more, the sound just had a DEPTH to it that you simply can't get by using less/smaller speakers but pushing them harder.

But for an old school bass sound, or most guitar sounds, you can used those pushed mids to get a little more character and get that liveliness. It's a fine line, but if you know right where it is, you can use it to step over to either side for great effect depending on the situation.

[Arjank]

Originally Posted by will33

To add....I read response charts and know at least somewhat what aort of peaks and valleys I like in the mid/upper frequencies and they've proven to translate to real life sound pretty well if you stick to low power and clean tone. Add more power and start making things bwhave in some different fashion and suddenly the 1w charts don't jive....they don't tell the whole story.

Unfortunately, I lack the material and financial resources to do multiple, high power and possibly destructive tests.....mostly 1w data sheets and ears over here.

Well, there's breakup and breakup
What I normally call breakup is the cone leading it's own "life" at a certain frequency(ies) also called a resonance-peak.
E.g most 15" drivers have such a breakup-node somewhere between 1.5 and 2.5khz. Such a peak gives most drivers their signature sound and does most to color the sound in the upper end of their frequency range. Cones that are "hard" (aluminium, ceramic) tend to have a more extreme peak(s) then "softer" cones(paper, polypropylene). You can also track these anomalies in the impedanceplot.
These peaks also often show a 3rd order harmonic distortion peak related to this breakup node(visible in distortiongraph)

Secondly we also have destructive cone resonances, often these are caused by the suspension(not having enough damping capabilities) and outer edge of the cone. E.g most 15" drivers have such a resonance somewhere between 400hz -700hz. Also a cause for muddy sounding low/mids....
This behavior is also visible in the impedanceplot.

Then, there is breakup cause by drivers exeeding their xmax(voice-coil is starting to leave the magnet gap). Actually this is not what I call breakup, the driver is now adding lot's of extra content(harmonics) to the original signal that is not there(the infamous fart-out sound). But it's also possible that when the suspension is hitting it's limits(xmech) the driver will create harmonics in the upper octaves of the drivers frequency range.
IMO I would like to not have a lot of extra harmonic content created this way because it's very unpredictable.
This behavior can be visualized in distortiongraphs done at different SPL levels.
All drivers add a certain amount of harmonic(2nd, 3rd, 5th order) content to the signal, good drivers keep this to a minimum so it's not audible.

There's also intermodulation distortion(also responsible for the fart-out sound). This becomes a problem when the driver has to make large excursions, voice-coil leaving the magnetic field and simultaniously has to produce higher frequencies. Good reason to use a dedicated mid-driver.

[Nephilymbass]

The speakers in cabs being different make them have different characteristics when pushed. An ampeg 810 sounds best when it's pushed hard but an swr Goliath cab sounds horrible when pushed hard. Just depends. I do think it has a lot to with what people buy. At home practicing volume I don't like the 810 at all but when you crank it up a lot more changes that just volume. The goliaths are nice turned down and sound like crap cranked up. Which is why a lot of players like them when they play them in the store but when it comes to a loud situation they don't

[will33]

That's where the fun happens, when you make them "work".

I don't need the "personalized PA system", or "rig that sounds like FOH" approach. We are a small outfit and I run my own sound. I crank the rig up to carry smaller places and mic it for larger stuff, so I put it's tone out front. No need for "clean DI and let the house handle it".....I am the house, and the bassplayer, and the roadie, and the backup singer, and the repairman...and....and...

[bikeplate]

Just buy a Bergantino and stop thinking about it.

[will33]

Originally Posted by bikeplate

Just buy a Bergantino and stop thinking about it.

But that wouldn't be nearly as much fun and I wouldn't be able to say "I made this thing that sounds this good".

[bikeplate]

Whatever u make won't sound as good as a Berg

[JGR]

Originally Posted by bikeplate

Whatever u make won't sound as good as a Berg

Not true.