long xmax: pros and cons

sokol · 17th June 2007, 09:40 AM

what are the pros and cons of long xmax in bass guitar drivers?

For sure pro is high power whitstand ability at low frequency. Any other pros? Any cons?

richie00boy · 17th June 2007, 09:45 AM

Linearity

Svante · 17th June 2007, 03:05 PM

In general:

A long xmax makes the driver capable of louder sound at low frequencies with less distortion.

A long xmax also reduces efficiency if the voice coil is underhung*; much of the coil is not subjected to magnetic field, which means that it will not deliver any force to the cone. It will just consume power and add weight to the moving system.

I can imagine that distortion is less of a problem in guitar loudspeakers, distortion may very well be a desired feature of the system. However, for hifi use, distortion is bad.

*Almost all drivers have underhung voice coils.

Hartono · 17th June 2007, 03:12 PM

Hi Svante,

"underhung*"

you mean overhung ?

Hartono

Svante · 17th June 2007, 07:17 PM

Quote:

Originally posted by Hartono
Hi Svante,

"underhung*"

you mean overhung ?

Hartono

Yes, of course. Sorry.

sokol · 18th June 2007, 10:59 AM

Sorry, did not understand "overhung". Does it mean, that coil is out of gap?

Hartono · 18th June 2007, 11:03 AM

yes the voice coil is longer than the gap

there's some way to keep linearity with overhung voice coil, this involve some technique in linearizing BL over excursion , and other techniques.

edit: usually if this technique is used in the driver, the manufacturer will mention it

Svante · 18th June 2007, 01:06 PM

Here are some pictures on over-/underhung voice coils:

http://en.wikipedia.org/wiki/Voice_coil

CeramicMan · 18th June 2007, 02:50 PM

I've found that one of the cons of high excursion drivers is fatiguing of the (rubber) surrounds. Because the surround is wider, it also has to be thicker, and it hardens after a while from all the flexing.

And maybe deep bass isn't the biggest problem? Lots of speakers can handle it. For a bass guitar I'm guessing you'll want deep bass and good performance up to around 400Hz, so that you can play a high G at ~196Hz and still reproduce the 2nd harmonic with a good 'attack'. How about using an array of smaller drivers instead of a single large one?

Hartono · 18th June 2007, 02:58 PM

I think for bass guitar application , the linearity is not the important one, the important one is how the end result "sound"

warm, full of tone , deep ... etc

17th June 2007, 09:40 AM	#1
sokol diyAudio Member Join Date: May 2007	long xmax: pros and cons what are the pros and cons of long xmax in bass guitar drivers? For sure pro is high power whitstand ability at low frequency. Any other pros? Any cons?

17th June 2007, 09:45 AM	#2
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	Linearity __________________ www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more

17th June 2007, 03:05 PM	#3
Svante diyAudio Member Join Date: Feb 2004 Location: Stockholm	In general: A long xmax makes the driver capable of louder sound at low frequencies with less distortion. A long xmax also reduces efficiency if the voice coil is underhung; much of the coil is not subjected to magnetic field, which means that it will not deliver any force to the cone. It will just consume power and add weight to the moving system. I can imagine that distortion is less of a problem in guitar loudspeakers, distortion may very well be a desired feature of the system. However, for hifi use, distortion is bad. Almost all drivers have underhung voice coils. __________________ Simulate loudspeakers: Basta! Simulate the baffle step: The Edge

18th June 2007, 01:06 PM	#8
Svante diyAudio Member Join Date: Feb 2004 Location: Stockholm	Here are some pictures on over-/underhung voice coils: http://en.wikipedia.org/wiki/Voice_coil __________________ Simulate loudspeakers: Basta! Simulate the baffle step: The Edge

18th June 2007, 02:50 PM	#9
CeramicMan diyAudio Member Join Date: Nov 2003 Location: Brisbane, QLD	I've found that one of the cons of high excursion drivers is fatiguing of the (rubber) surrounds. Because the surround is wider, it also has to be thicker, and it hardens after a while from all the flexing. And maybe deep bass isn't the biggest problem? Lots of speakers can handle it. For a bass guitar I'm guessing you'll want deep bass and good performance up to around 400Hz, so that you can play a high G at ~196Hz and still reproduce the 2nd harmonic with a good 'attack'. How about using an array of smaller drivers instead of a single large one? __________________ Lech


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17th June 2007, 03:12 PM	#4
Hartono diyAudio Member Join Date: Nov 2002 Location: currently in China	Hi Svante, "underhung*" you mean overhung ? Hartono

18th June 2007, 10:59 AM	#6
sokol diyAudio Member Join Date: May 2007	Sorry, did not understand "overhung". Does it mean, that coil is out of gap?

18th June 2007, 11:03 AM	#7
Hartono diyAudio Member Join Date: Nov 2002 Location: currently in China	yes the voice coil is longer than the gap there's some way to keep linearity with overhung voice coil, this involve some technique in linearizing BL over excursion , and other techniques. edit: usually if this technique is used in the driver, the manufacturer will mention it

18th June 2007, 02:58 PM	#10
Hartono diyAudio Member Join Date: Nov 2002 Location: currently in China	I think for bass guitar application , the linearity is not the important one, the important one is how the end result "sound" warm, full of tone , deep ... etc

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