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jwc

Bass horn ideas again. A possible build. Need criticism.

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Thank, James... I've had my eye on the BP102 already. The 4 ohm has lower QES, but it's a little bumpy reponse above 200hz. Things model different in horns, though, so it might work. I'm stiil clueless with horn response.

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Have you used "guitar speakers" in bass horns before? I thought they go with smaller voice coils (larger unsupported diaphragm area) and thinner diaphragms so they can get intentional cone breakup to get that nice distorted guitar cab sound?

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That's for a bass and it's a 10, pretty stiff with rather good xmax.

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Have you used "guitar speakers" in bass horns before? I thought they go with smaller voice coils (larger unsupported diaphragm area) and thinner diaphragms so they can get intentional cone breakup to get that nice distorted guitar cab sound?

I have heard of good results with the EVM 12L.  Haven't tried it myself.  I used to be able to score those for $150.00 until Zakk Wylde with Black Label Society starting using them.  Now they seem to go for much more than that.

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I had a pair of EVM 12L I got from JWC, but eventually sold them. Great speakers. Didn't Bruce Edgar use them in zome horns? Mesa used them in some of their guitar amps.

Bruce

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But how do you know it's stiff? Serious question btw.

 

Just to play devil's advocate - there is no shortage of people enjoying the results of all sorts of designs that I would personally consider mediocre. Maybe someone enjoys the distortion from these drivers? Not to imply that there is distortion there - just trying to explain some skepticism.

 

The thing is, the design of most guitar cabs (and I'm including bass in the guitar category) is often going to lend itself towards T/S params that would be good for horns. I had always just avoided the category based on what I was led to believe made a good sounding guitar cab. Assymetric motor assemblies, softer cones, etc... I guess in a horn one could argue that the driver excursion is way reduced to make those issues less problematic?

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I get where you are coming from, Mike. I think the t/s parameters and other specs might help narrow the field, but only to a point. Sooner or later you have to make sawdust. Then, test, listen, adjust, test, listen... keep going, change drivers, design...

A company brings together talented, smart engineers an provides the resources to let them do their job. Someone working at home... depends on the same thing, but a lot of these may never get good testing, only using ears to be interpreting the work. However, inexpensive tools are available.

Bruce

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Doc.

 

Horn loaded woofer designed for Guitar bass.......what frequencies is there noted distortion?  For us novel folks here.....and not pro musicians......we may listen to this type of build to 400-600Hz only.  There is distortion there?

 

I'm not sure I've ever seen a distortion plot on this....never thought about it till now.

 

jc

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I would think you'd want the guitar cab distortion to be as broadband as possible so that it doesn't sound "one-notey" in its timbre.

 

Maybe I could get around to measuring distortion of the various guitar cabs I have access to. I've always been curious about what it looks like. I too have never seen anything quantifying that kind of performance....

 

Actually, I was talking with my coworkers while writing this and they mentioned having seen some studies. We're in China watching the paint dry as we bring up all our manufacturing and test fixtures. Anyways, here's an interesting article:

http://legacy.spa.aalto.fi/dafx08/papers/dafx08_17.pdf

The last page shows a good distortion summary - the rest of the article took me a bit to wrap my head around. I think one of the interesting things they were exploring is the corrugation on the cone and the frequency specific velocity at each point.

 

Or here's a more human readable article:

http://www.soundonsound.com/sos/feb12/articles/speakers.htm

 

And an interesting quote from Ian White (of Celestion):

"Designing guitar speakers is, in many ways, much more challenging than pro PA or hi-fi, because guitar speakers are so non-linear,” he says. "Hi-fi speakers are designed for linear operation mainly within what's called their 'pistonic band', the region where the speaker is moving in and out in linear fashion. Above that band, the speaker goes into 'break-up' — instead of the whole thing acting coherently like a pump or piston, little bits of the cone are all doing their own thing — but then you'd typically move that part of the signal over to, say, a mid-range driver or tweeter. With guitar speakers, there's almost no pistonic band. Within their usable frequency range, it's almost all break-up.”

 

and

"The effect of signal level is not huge,” says Ian White, "and certainly not as big as it is on the amplifier. These cone break-up mechanisms happen at a few microvolts input. You don't need to drive 20 Volts into the thing to make them happen. There are some level-related effects that come into play, but they're not the ones we've been talking about up to now.

 

It seems to me like the idea of pistonic motion is completely thrown out the window with these drivers? Obviously these are broad brush strokes so maybe there are exceptions to the trend? I dunno. I just know when I was designing my own bass guitar cabinets that we didn't like the sound of the ultra linear hi-fi drivers. We ended up going with an aluminum diaphragm Eminence driver because it had the sound my buddy was going for....really crisp because of how the aluminum would distort. The paper drivers couldn't give us that level of crispness and still have the bottom end we were looking for (he played a five string).

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That is an interesting explanation I've never heard as the difference between the two. Thanks for sharing.

However, again.......I wonder how the "break-up" design could/can contribute to sub 400Hz distortion. I don't notice the non-linear curve as much with these drivers in this frequency.

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I'd say for sure the breakup is getting into the 400Hz region, but I'm not sure how much lower it goes. Maybe another octave? As you go lower, cone excursion increases so at the lowest octaves I think the motor linearity probably dominates. I think a lot of these systems are using overhung coils and weaker sauce magnets.

Here's a dude talking about AlNiCo mojo:

http://www.tedweber.com/lets-talk-speakers/

"The whole 'AlNiCo mojo' is about smooth compression at high average levels, such as what you would have running the amp flat out. AlNiCo (Aluminum-Nickel-Cobalt) is an alloy magnet and all alloy magnets are easier to demagnetize than comparable Ceramic (Strontium Ferrite) magnets. What this means is that as the voice coil starts moving in response to the input signal, it generates a magnetic field of its own that tries to demagnetize the magnet. As its effect lowers the available magnetic field of the AlNiCo magnet, the speaker becomes less efficient, the voice coil moves less, etc. The physics of it is that the small magnets near the surface of the magnet poles (called 'domains') begin to change state, or flip directions. The result is smooth compression, the same kind of operating curve compression that occurs in a tube amplifier."

Edited by DrWho

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Double post.

Edited by DrWho

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