Can someone help me design an attenuator?

Boscoe · 10th October 2010, 01:36 PM

I need one for each of my 2 way moniters, with a flat sweep the bass is considerably lower volume so I have to have the bass turned up on my preamp which I don't like. The problem is I have no idea to how much I need to 'quieten' the tweeter to meet the woofers volume. Both drivers are a 8 ohm and are crossed at 3KHz.

Thanks
Boscoe

Dr.EM · 10th October 2010, 01:45 PM

Padding the tweeter won't have the same effect as the bass lift control on your pre-amp. The control on your pre-amp probably boosts around the 100Hz and under range, if you pad the tweeter you'll effectively boost 3kHz and under, it will effect a lot more than just the bass end! Why do you dislike using the tone control if it does what you want it to?

Boscoe · 10th October 2010, 01:47 PM

It's not vital but I like the speakers to have a flat response then change the the tone control. Don't know really just how I want them!!

David Gatti · 10th October 2010, 01:50 PM

Open up the speaker and tell us what's in the crossover.
Best approach will be to increase the resistor value in series with the tweeter.

wakibaki · 10th October 2010, 01:57 PM

I'd take aboard what has already been said, but for future reference, just google 'speaker attenuator calculator'.

L-Pad (Driver Attenuation Circuit) Designer / Calculator

w

Boscoe · 10th October 2010, 02:36 PM

This is the crossover I am using:

David Gatti · 10th October 2010, 11:12 PM

OK, that 2.5 ohm/12 ohm resistor combination is giving about 3.5dB attenuation to the tweeter..

I suggest you reduce the 12 ohm resistor to 8 ohms and increase the 2.5 ohm resistor to 3.5 ohms. That will give about 5.5 dB attenuation (i.e. an extra 2 dB), without altering the 3kHz crossover point.

giralfino · 11th October 2010, 08:17 AM

Just a few questions:
is it a commercial speaker or a diy one?
the 300-500 Hz region is also lower volume than the treble?
In my limited experience I would say that there isn't a correct BSC.
Ralf

Boscoe · 11th October 2010, 08:23 AM

It's a diy build. I don't know what BSC is?

giralfino · 11th October 2010, 08:44 AM

BSC = Baffle Step Conpensation
For an explanation of the baffle step effect see (for example): Baffle Diffraction Step
Here you can find a useful (an free) software that can simulate the effect: Baffle Diffraction Simulator
The compensation of the effect is done primarily with the main woofer inductor, for you that means you have to rework the entire crossover.
Ralf

10th October 2010, 01:36 PM	#1
Boscoe diyAudio Member Join Date: Feb 2010 Location: England	Can someone help me design an attenuator? I need one for each of my 2 way moniters, with a flat sweep the bass is considerably lower volume so I have to have the bass turned up on my preamp which I don't like. The problem is I have no idea to how much I need to 'quieten' the tweeter to meet the woofers volume. Both drivers are a 8 ohm and are crossed at 3KHz. Thanks Boscoe

10th October 2010, 01:45 PM	#2
Dr.EM diyAudio Member Join Date: Oct 2006 Location: Swindon	Padding the tweeter won't have the same effect as the bass lift control on your pre-amp. The control on your pre-amp probably boosts around the 100Hz and under range, if you pad the tweeter you'll effectively boost 3kHz and under, it will effect a lot more than just the bass end! Why do you dislike using the tone control if it does what you want it to? __________________ My music page 3-Way system build thread

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10th October 2010, 01:47 PM	#3
Boscoe diyAudio Member Join Date: Feb 2010 Location: England	It's not vital but I like the speakers to have a flat response then change the the tone control. Don't know really just how I want them!!

10th October 2010, 01:50 PM	#4
David Gatti diyAudio Member Join Date: Mar 2004 Location: Melbourne, Australia	Open up the speaker and tell us what's in the crossover. Best approach will be to increase the resistor value in series with the tweeter.

10th October 2010, 01:57 PM	#5
wakibaki Banned Join Date: Jan 2008 Blog Entries: 2	I'd take aboard what has already been said, but for future reference, just google 'speaker attenuator calculator'. L-Pad (Driver Attenuation Circuit) Designer / Calculator w

10th October 2010, 02:36 PM	#6
Boscoe diyAudio Member Join Date: Feb 2010 Location: England	This is the crossover I am using:

10th October 2010, 11:12 PM	#7
David Gatti diyAudio Member Join Date: Mar 2004 Location: Melbourne, Australia	OK, that 2.5 ohm/12 ohm resistor combination is giving about 3.5dB attenuation to the tweeter.. I suggest you reduce the 12 ohm resistor to 8 ohms and increase the 2.5 ohm resistor to 3.5 ohms. That will give about 5.5 dB attenuation (i.e. an extra 2 dB), without altering the 3kHz crossover point.

11th October 2010, 08:17 AM	#8
giralfino diyAudio Member Join Date: Feb 2009	Just a few questions: is it a commercial speaker or a diy one? the 300-500 Hz region is also lower volume than the treble? In my limited experience I would say that there isn't a correct BSC. Ralf

11th October 2010, 08:23 AM	#9
Boscoe diyAudio Member Join Date: Feb 2010 Location: England	It's a diy build. I don't know what BSC is?

11th October 2010, 08:44 AM	#10
giralfino diyAudio Member Join Date: Feb 2009	BSC = Baffle Step Conpensation For an explanation of the baffle step effect see (for example): Baffle Diffraction Step Here you can find a useful (an free) software that can simulate the effect: Baffle Diffraction Simulator The compensation of the effect is done primarily with the main woofer inductor, for you that means you have to rework the entire crossover. Ralf

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