Martin Audio W8LC question

meaghers · 10th September 2007, 08:46 PM

I work with some W8LC boxes which consist of:

12" (300mm)/3" (75mm) voice coil,
Hybrid™ bass horn loaded
2 x 6.5" (165mm)/1.5" (38mm) coil drivers,
horn loaded
3 x 1" (25mm) exit HF compression drivers,
horn loaded

They are designed to be used with external active crossovers made by Lake.

My question is this, on the back of the NL8 input panel is a network of capacitors and resistors which are connected to the HF Drivers. Being a novice, I initially assumed that it was a xover network, but these boxes are externally crossed over, and the cap/resistor network is only connected to the HF drivers.

What is this network? What does it do? Does it have something to do with the HF's being compression drivers? Just curious.

v-bro · 11th September 2007, 06:00 PM

I assume (as I'm not familiar with the design) it is there to protect the high frequency driver against DC/low freqs... And some attenuation?

wigginjs · 11th September 2007, 07:09 PM

Picture or (preferably) schematic of this network? It should be pretty easy to tell it's effect from the schematic.

meaghers · 11th September 2007, 10:32 PM

I quickly drew up a diagram in mspaint. I hope it's clear enough.

obviously, the large cap is 10 uF, the 2 small ones are 1 uF, and the resistor is 12 ohms.

wigginjs · 11th September 2007, 11:00 PM

Well, I'd have to know the impedance of the tweeter to tell you more, but that circuit creates a 1st order high pass network (6dB/oct, and the 10uF means it's probably at a fairly low frequency) and then reduces the lower end of the tweeter response (effectively "boosting" the upper end the response by comparison). I don't know at what point it begins the boost, but the 2uF (effective) cap would suggests it starts fairly low (4Khz? Lower?) and the 12ohm resistor provides a fairly significant cut. It probably does this because the tweeter response rolls off at higher frequencies.

meaghers · 11th September 2007, 11:13 PM

The datasheet says the HF drivers are 8 Ohms, but I assume that's all 3 drivers in parallel.

wigginjs · 12th September 2007, 12:02 AM

Well, if the network applies to all three drivers then you would consider their combined impedance.

cibercut · 24th July 2010, 08:04 PM

May be someone have a drawing W8LC ???
Send me please cibercut@yandex.ru

Ferrit37 · 24th July 2010, 08:28 PM

Professional Loudspeaker Systems. Martin Audio Ltd.

10th September 2007, 08:46 PM	#1
meaghers diyAudio Member Join Date: Mar 2006 Location: Vancouver BC	Martin Audio W8LC question I work with some W8LC boxes which consist of: 12" (300mm)/3" (75mm) voice coil, Hybrid™ bass horn loaded 2 x 6.5" (165mm)/1.5" (38mm) coil drivers, horn loaded 3 x 1" (25mm) exit HF compression drivers, horn loaded They are designed to be used with external active crossovers made by Lake. My question is this, on the back of the NL8 input panel is a network of capacitors and resistors which are connected to the HF Drivers. Being a novice, I initially assumed that it was a xover network, but these boxes are externally crossed over, and the cap/resistor network is only connected to the HF drivers. What is this network? What does it do? Does it have something to do with the HF's being compression drivers? Just curious.

11th September 2007, 06:00 PM	#2
v-bro diyAudio Member Join Date: May 2006	I assume (as I'm not familiar with the design) it is there to protect the high frequency driver against DC/low freqs... And some attenuation? __________________ Max. cone displacement can be several foot on any speaker!Too bad it can be done only once......

11th September 2007, 07:09 PM	#3
wigginjs diyAudio Member Join Date: Dec 2003 Location: Columbia, SC	Picture or (preferably) schematic of this network? It should be pretty easy to tell it's effect from the schematic. __________________ The Four Chairs DIY Home Theater

11th September 2007, 11:00 PM	#5
wigginjs diyAudio Member Join Date: Dec 2003 Location: Columbia, SC	Well, I'd have to know the impedance of the tweeter to tell you more, but that circuit creates a 1st order high pass network (6dB/oct, and the 10uF means it's probably at a fairly low frequency) and then reduces the lower end of the tweeter response (effectively "boosting" the upper end the response by comparison). I don't know at what point it begins the boost, but the 2uF (effective) cap would suggests it starts fairly low (4Khz? Lower?) and the 12ohm resistor provides a fairly significant cut. It probably does this because the tweeter response rolls off at higher frequencies. __________________ The Four Chairs DIY Home Theater

12th September 2007, 12:02 AM	#7
wigginjs diyAudio Member Join Date: Dec 2003 Location: Columbia, SC	Well, if the network applies to all three drivers then you would consider their combined impedance. __________________ The Four Chairs DIY Home Theater


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24th July 2010, 08:04 PM	#8
cibercut diyAudio Member Join Date: Aug 2005	May be someone have a drawing W8LC ??? Send me please cibercut@yandex.ru

24th July 2010, 08:28 PM	#9
Ferrit37 diyAudio Member Join Date: Apr 2007	Professional Loudspeaker Systems. Martin Audio Ltd. __________________ Warmest regards, Ferrit37

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