ehh, voice coil is 12mm underhung, in a 12.7mm
magnet gap, gives +/- 0.35mm xmax
Hi,
Linear Xmax is 0.35mm but that is not the point. Clearly the
driver will progressively distort above linear Xmax. At 3mm
excursion effective coil length in the gap is is varying +/- 25%.
This clearly will produce distortion. Now up excursion to 6mm and
compare the driver to a short gap (4mm) and long coil (10mm).
The latter is certainly a lot cleaner up to 3mm, the former
will progressively produce lots more 2nd and 3rd harmonic.
However at 6mm the latter driver will be having paroxysms,
producing more distortion than the former at all harmonics
and notably lots more higher harmonics above the third.
Meanwhile the former from 3mm to 6mm simply produces
more 2nd and 3rd harmonic distortion and doesn't produce
the nasty higher harmonics that the former does.
Its all a consequence of the shape of the BL curve vs. excursion.
Music drivers tend to have longer gaps and near equal length coils.
(By music I mean guitar, less bass, less keyboard, the least PA.)
Theoretically you want a well damped bass alignment given the
small signal parameters, as when you crank it up the large
signal parameters can only be worse in terms of damping.
There is some good stuff on the klippel.de website.
rgds, sreten.
It would be interesting to to plot the frequency response
of that Aura at various higher power levels, as Q will
increase. Further to that an undersized port can
exploited to use "port blocking" at high levels.
Music cabinets are not hifi cabinets.
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not sure I like the idea to constantly push it beyond the linear xmax
comparing 3mm to 0,35mm says the distortion will be 10 times higher
Hi,
No it doesn't follow at all, the BL curve determines such things.
Drivers for guitar especially, have no real linear Xmax by design.
rgds, sreten,
better bass guitar woofers are more like pro PA woofers
going to try this one http://www.faneinternational.com/downloads/FANE_Sovereign_12300_Specs.pdf
(just comparing apples to apples)
Hi,
That is a matter of biased personal opinion rather than fact.
An externally hosted image should be here but it was not working when we last tested it.
The "15” Fender® Special Design Speaker" I'd say is not
designed with PA principles in mind, though of course
some do apply. In particular the drivers distortion
profile would likely not suit a PA application.
rgds, sreten.
http://www.klippel.de/uploads/media/Loudspeaker_Nonlinearities–Causes_Parameters_Symptoms_06.pdf
See Fig 5 and the related figures 24 to 26.
in the cheap department, it is true, yes
man, they are going to make money on that, somehow
ofourse they cant use a woofer that eats up the budget of the whole combo
question is whether you need more than that
most of the time, I guess it will do ok
one strange thing I have noticed about the quality bass/guitar woofers, some are quite expencive
and I really cant see why
most still look like cheap iron woofers to me
man, they are going to make money on that, somehow
ofourse they cant use a woofer that eats up the budget of the whole combo
question is whether you need more than that
most of the time, I guess it will do ok
one strange thing I have noticed about the quality bass/guitar woofers, some are quite expencive
and I really cant see why
most still look like cheap iron woofers to me
hmm, I see
its claimed that when poleplate and voice coil are equal, it works like ordinary overhung, but with the benefit of a thick poleplate amd shorter voice coil
sure hope the magic works
are we going to look at big PA midwoofers with very short Xmax in a completely new way
though all being overhung, some of the very high sensitivity midwoofers also have near equal voice coil and poleplate
and some of the new designs(expencive) are also getting thicker poleplate, like 10-12mm
Looking at the comparison of Kms(x) and Bl(x) in Table 4 I'm not sure I agree with you regarding the source of harmonic distortion.
But it's not harmonic distortion we're concerned with. It's peak compression. Klippel's paper is focused on measuring the distortion components of non-linearity in linear drivers. It does not seem to address the maximum limits of non-linear drivers. That is, it assumes linearity and considers non-linearity to be a problem. That's like some hack automotive writer asserting the Porsche 911's tendency to hang it's tail out is a problem.
Speakers are suitable for MI use because they compress the peaks generated by the instrument's pickups. The distortion noted for equal-length motors is largely due to the magnet having less control over the coil as it leaves the gap. This lack of control means it's left to the suspension to keep the speaker from bottoming out when a player slaps his bass.
Wow, I sure appreciate all this information- it'll take me a while to get up to speed here- I have very limited internet access, and I can print some stuff but hesitate to print a 69 page paper. I will print this thread out and study it some- I can't do it justice right now.
One thing I have been very unclear on is how multiple drivers affect bass reflex tuning of a cab- that 1/3 cu ft driver has had anywhere from 6 to 10 of these 5 1/4" drivers in it... Sounds like it "should" be 6-10 times the internal volume!
I was interested to see some of the Scanspeak drivers have quite large xmax figures- 10 mm for the 7" Classic. I was thinking those might be appropriate. I'll look into all this about coil gaps.
FWIW I am expecting to have to carefully monitor the way I play the bass at every moment not to blow things up- not just go for it and expect the system to sound good. This is perhaps due to my perspective from playing the drums- Just the right touch is required to create beautiful tones and balances- just whanging away it gets really ugly really fast, painful even. So I am not proposing this rig will make life safe for anybody doing anything on a bass guitar, but just for me being very careful the whole time, which actually I enjoy.
One thing I have been very unclear on is how multiple drivers affect bass reflex tuning of a cab- that 1/3 cu ft driver has had anywhere from 6 to 10 of these 5 1/4" drivers in it... Sounds like it "should" be 6-10 times the internal volume!
I was interested to see some of the Scanspeak drivers have quite large xmax figures- 10 mm for the 7" Classic. I was thinking those might be appropriate. I'll look into all this about coil gaps.
FWIW I am expecting to have to carefully monitor the way I play the bass at every moment not to blow things up- not just go for it and expect the system to sound good. This is perhaps due to my perspective from playing the drums- Just the right touch is required to create beautiful tones and balances- just whanging away it gets really ugly really fast, painful even. So I am not proposing this rig will make life safe for anybody doing anything on a bass guitar, but just for me being very careful the whole time, which actually I enjoy.
expencive experiment
anyway, using small hifi woofers, make sure you get some with very strong cones
or else you else you will have serious cone breakup distortion when pulling the strings hard, and I mean real serious and nasty cone breakup
and the huge downside of a strong cone in a small woofer is really low sensitivity
seems you could be facing serious trouble
Jumping in here very much at the end of this discussion let me add a little bit of different thinking here. I have been making speakers and systems for quit a while. You have to look at the type of music you are playing in this discussion. A Jazz bass player is going to want a different sound than a rock bass player. I have done some things that a Jazz player likes that produces a more clean clear sound that a rock bass would hate. Rock is looking for that overdriven dirty sound and jazz could want more of the stand up bass clean sound. Typically musical instrument loudspeakers are not linear in any way, they are distortion producers and that is part of what we have come to think of as a musical sound. As soon as you replace the speakers with a linear low distortion speakers you will loose that quality. I don't think that at first when electric guitars were invented this was the intention but it was the result. So musical equipment manufacturers have had the benefit of being able, and actually needing to use low quality distortion producers. These are typically short coils in a short gap, the coil leaving the short linear range of the device is what is making the sound, that crunch that a guitar player is looking for. Bass guitar is a bit different only in that you are looking for a bit more excursion due to the lower frequency you are trying to produce. I have a 6 1/2" speaker with extremely long excursion and low distortion and I would think that a musician would hate the clean sound with limited or no third and higher order distortion characteristics. Hi-fidelity speakers are not compatible with musical instrument sound production. This is not only my opinion, but what I have been told by other musicians many times.
Steven
Steven
I dont understand
are you saying a small hifi woofer distorts less than my advanced 15" with triple alu rings in the magnet system
Attachments
tinitus,
I couldn't say that for sure but just making something look nice and putting a big magnetic structure on a speaker won't necessarily produce a low distortion device there is much mote to it than that. My point was not even size related. It was that most musicians are not going to like the sound of any low distortion speaker when they are trying to play music through them, that is play the instrument, not listening to it after it is recorded. Playing music through a clean clear sounding speaker does not necessarily and most often doesn't make nice music.
I couldn't say that for sure but just making something look nice and putting a big magnetic structure on a speaker won't necessarily produce a low distortion device there is much mote to it than that. My point was not even size related. It was that most musicians are not going to like the sound of any low distortion speaker when they are trying to play music through them, that is play the instrument, not listening to it after it is recorded. Playing music through a clean clear sounding speaker does not necessarily and most often doesn't make nice music.
I had a Holy Grail experience with an old but mint JBL D-130 with this bass and this 500 watt tube studio monitor amp flat to 10 hz. I found that when I got the signal chain from pickup to power amp as simple as possible, to the extent even of plugging directly into the power amp after removing the tone controls from the signal path- even replacing them with a resistor smeared the low notes, so straight from pickup to power amp- and then set the power amp for minimum negative feedback and minimum low rolloff- I suddenly attained an utterly gorgeous sound that felt and sounded thrillingly *acoustic*! It was like I was no longer playing an electric instrument. I adjusted the pole pieces on the pickup to an appropriate level and I could play comfortably on the top three strings without upsetting the speaker, but I had to be careful with the low E as it was clear I could blow the speaker quite easily. Still, it brought tears to my eyes, and not only mine, it was so very beautiful and natural- and that remains my personal tone ideal for bass.
This was not the instrument version, this was the D-130 meant for hi fi.
Sadly I blew that gorgeous thing playing 36 hot watts of guitar through it and then hooking it up to a solid state amp...
A lot of my reason for seeking out new speakers is that while these 5" speakers designed to be bass speakers have a lot going for them- I'm sure I just have my bass reflex cab designed wrong- they just don't have that gorgeous acoustic tone.
This was not the instrument version, this was the D-130 meant for hi fi.
Sadly I blew that gorgeous thing playing 36 hot watts of guitar through it and then hooking it up to a solid state amp...
A lot of my reason for seeking out new speakers is that while these 5" speakers designed to be bass speakers have a lot going for them- I'm sure I just have my bass reflex cab designed wrong- they just don't have that gorgeous acoustic tone.
tapehead ted,
The JBL D-130 with the metal dust cap was a musical instrument speaker, they just happen to sound great as a speaker for listening to music also. I would get that driver re-coned and use it, they sound beautiful. The cabinet that you would use that speaker in would be different for a guitar and for listening to music. the guitar cabinet would usually be an open backed cabinet while for music reproduction you would use a bass reflex or sealed enclosure. By the way they also work great in a bass horn, been there done that.
The JBL D-130 with the metal dust cap was a musical instrument speaker, they just happen to sound great as a speaker for listening to music also. I would get that driver re-coned and use it, they sound beautiful. The cabinet that you would use that speaker in would be different for a guitar and for listening to music. the guitar cabinet would usually be an open backed cabinet while for music reproduction you would use a bass reflex or sealed enclosure. By the way they also work great in a bass horn, been there done that.
Hi, I've said that several times, so design it properly, rgds, sreten.
Its pointless having an opinion based on bad design.
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Thanks all. I need to RFM in a big way and will be researching that- book recommendations anyone? I'll be searching for some...
What does that JBL D130 experience tell anyone informed about the kind of speakers I'm after? That was lovely, but this 5" mini line array approach is giving me the coverage off axis that I'm after. My info is that things get omnidirectional where the piston diameter is 1/4 wavelength of the frequency, so these 3 1/2" pistons on the 5 1/4" speaker are giving me something like omni at something like 750 hz. That's the theory- the practice is that my experimental cabs are giving me beautiful nearly seamless offaxis response. Once I RFM and get the cab volume right, I suspect these little speakers will behave in the low end, like they did in the "donor" cab. But the tone will still fall short of the exquisitely acoustic...
The JBL is long gone... from what I understand the voice coil gap on those was so very small they just can't make them like that anymore, and a recone becomes a different animal completely.
So I'm off to Read the F'inM... still I appreciate any outside insights on the kind of hifi speaker I might be advised to abuse here, since I don't know of any other 5-6" instrument speakers.
And thanks again!
What does that JBL D130 experience tell anyone informed about the kind of speakers I'm after? That was lovely, but this 5" mini line array approach is giving me the coverage off axis that I'm after. My info is that things get omnidirectional where the piston diameter is 1/4 wavelength of the frequency, so these 3 1/2" pistons on the 5 1/4" speaker are giving me something like omni at something like 750 hz. That's the theory- the practice is that my experimental cabs are giving me beautiful nearly seamless offaxis response. Once I RFM and get the cab volume right, I suspect these little speakers will behave in the low end, like they did in the "donor" cab. But the tone will still fall short of the exquisitely acoustic...
The JBL is long gone... from what I understand the voice coil gap on those was so very small they just can't make them like that anymore, and a recone becomes a different animal completely.
So I'm off to Read the F'inM... still I appreciate any outside insights on the kind of hifi speaker I might be advised to abuse here, since I don't know of any other 5-6" instrument speakers.
And thanks again!
and the 'well known' power compression ?
from my experience most hifi drivers begin to distort pretty fast, with just moderately loud SPL
but maybe its true what was just said, that opinions based on poor designs makes little sense (well, I guess it depends on the opinion too
)btw, I had a bass combo where the sound was basicly based on EQ
sounded pretty bad straight, without the EQ
and too artificial with the EQ, and 'ear-bleeding'
I think you are either simplificating things too much, or you dont know enough about how it really works playing bass
not that I know either, but I cannot recognize much of what is said
sounds more like just talking about it
and another btw, after I built my own, I do not have any 'hearing issues'
which was a real big problem before, and enough to make me consider quit playing, completely
now I can play all I want, no problems
so how about that ?
The JBL D-130 was originally designed for hi-fi, it later found limited use in musical instrument speakers. The D-140 I believe was more targeted at the musical instrument market.
Lansing Heritage has a lot more detail on this sort of stuff.
The D-130 is a great wide range low mms woofer, but has rather limited xmax. Sounded great in the right box. (I had a pair)
Lansing Heritage has a lot more detail on this sort of stuff.
The D-130 is a great wide range low mms woofer, but has rather limited xmax. Sounded great in the right box. (I had a pair)
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