Need Simple Help

VectorSpace · 25th October 2009, 07:55 PM

Hey guys. I'm building an 2-band crossover and there is one very simple thing I don't understand: what amplifiers do I use after the signal has been passed through the crossover?

OK, so if this is my system setup:

How do I determine what amplifier I need right before the sub, and before the tweeter?

Francec · 25th October 2009, 11:51 PM

Hi Vector,
What is the crossover frequency, which drivers are you using and what do you want of the speaker?

Frank

VectorSpace · 26th October 2009, 01:29 AM

Hey Francec. Thanks for the quick reply. I know about electronics, but I am brand new to the audio circuits. Here is a MultiSim Schematic I made of the crossover.
http://i586.photobucket.com/albums/s...rSchematic.jpg

And here is a dB Gain frequency response plot of each output.
http://i586.photobucket.com/albums/s...cyResponse.jpg

From that info could you help me figure out what the crossover frequency is, which drivers I want and what I do want of the speaker?

These are new concepts to me. Much help needed.

PeteMcK · 26th October 2009, 03:08 AM

BiAmp (Bi-Amplification - Not Quite Magic, But Close) - Part 1

Moondog55 · 26th October 2009, 07:14 AM

Tweeters only need a few watts so use the smallest amp you have for the HF I use 250watts for my midrange and 250 for the bass, when I Tri-amp I have a little 70watt amp here and I think that is probably just a little too much

VectorSpace · 26th October 2009, 08:09 PM

Do typical computer speakers have a little amp in it already?

If so, then could I just use one of those as to pass the high's to?

And a 250W amp would do fine to power the Sub to pass the low's to?

Once again, I know little about audio. So any advice helps me out.

wakibaki · 26th October 2009, 08:56 PM

You can do this, but powered speakers rarely have as much as 10W rms and often sound bad when driven hard. 250W is probably way too much to go with computer speakers, a typical COTS system has 8W L&R with 22W sub.

w

PeteMcK · 26th October 2009, 10:58 PM

"How do I determine what amplifier I need"
- base this on a: how loud you want to play; b: how big your room is; c: your budget.
in theory, for headroom, you need the same size amp for HF as LF, in practise you can get away with a somewhat smaller amp for HF.
Of course, you need to decide this and the crossover freq of the crossover unit AFTER you've decided on your speakers.
It's not clear whether you're going for a sub+satelite or 2-way woofer + tweeter system.
typical computer speakers and their amps are a waste of time.
For speakers of reasonable efficiency, 40w is more than adequate

VectorSpace · 26th October 2009, 11:20 PM

I'm not really that interested in quality. This is for a school project. I just need to demonstrate that I am splitting the audio spectrum into two separate frequency bands.

So what speakers and amps would you guys use to achieve this goal?

Pano · 27th October 2009, 02:43 AM

It doesn't matter what amps you use, as long as they have "enough" power. And it matters that they have a volume control.

The main thing you want to worry about is that you get the gain right. Everything after that is just frosting on the cake.

25th October 2009, 07:55 PM	#1
VectorSpace diyAudio Member Join Date: Oct 2009	Need Simple Help Hey guys. I'm building an 2-band crossover and there is one very simple thing I don't understand: what amplifiers do I use after the signal has been passed through the crossover? OK, so if this is my system setup: How do I determine what amplifier I need right before the sub, and before the tweeter?

25th October 2009, 11:51 PM	#2
Francec Banned Join Date: Jul 2006 Location: Port Melbourne, Australia	Two way active Hi Vector, What is the crossover frequency, which drivers are you using and what do you want of the speaker? Frank

26th October 2009, 03:08 AM	#4
PeteMcK diyAudio Member Join Date: Feb 2002 Location: Sydney	BiAmp (Bi-Amplification - Not Quite Magic, But Close) - Part 1 __________________ ‘today… there lives alongside the twentieth century the tenth or thirteenth. A hundred million people use electricity and still believe in the magic power of signs and exorcisms” Trotsky

26th October 2009, 07:14 AM	#5
Moondog55 diyAudio Member Join Date: Jun 2007 Location: Norlane; Geelong: Victoria: Australia	Tweeters only need a few watts so use the smallest amp you have for the HF I use 250watts for my midrange and 250 for the bass, when I Tri-amp I have a little 70watt amp here and I think that is probably just a little too much __________________ QUOTE" The more I know, the more I know, I know (insert maniacal laugh >here<) NOTHING"

26th October 2009, 10:58 PM	#8
PeteMcK diyAudio Member Join Date: Feb 2002 Location: Sydney	"How do I determine what amplifier I need" - base this on a: how loud you want to play; b: how big your room is; c: your budget. in theory, for headroom, you need the same size amp for HF as LF, in practise you can get away with a somewhat smaller amp for HF. Of course, you need to decide this and the crossover freq of the crossover unit AFTER you've decided on your speakers. It's not clear whether you're going for a sub+satelite or 2-way woofer + tweeter system. typical computer speakers and their amps are a waste of time. For speakers of reasonable efficiency, 40w is more than adequate __________________ ‘today… there lives alongside the twentieth century the tenth or thirteenth. A hundred million people use electricity and still believe in the magic power of signs and exorcisms” Trotsky


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26th October 2009, 01:29 AM	#3
VectorSpace diyAudio Member Join Date: Oct 2009	Hey Francec. Thanks for the quick reply. I know about electronics, but I am brand new to the audio circuits. Here is a MultiSim Schematic I made of the crossover. http://i586.photobucket.com/albums/s...rSchematic.jpg And here is a dB Gain frequency response plot of each output. http://i586.photobucket.com/albums/s...cyResponse.jpg From that info could you help me figure out what the crossover frequency is, which drivers I want and what I do want of the speaker? These are new concepts to me. Much help needed.

26th October 2009, 08:09 PM	#6
VectorSpace diyAudio Member Join Date: Oct 2009	Do typical computer speakers have a little amp in it already? If so, then could I just use one of those as to pass the high's to? And a 250W amp would do fine to power the Sub to pass the low's to? Once again, I know little about audio. So any advice helps me out.

26th October 2009, 08:56 PM	#7
wakibaki Banned Join Date: Jan 2008 Blog Entries: 2	You can do this, but powered speakers rarely have as much as 10W rms and often sound bad when driven hard. 250W is probably way too much to go with computer speakers, a typical COTS system has 8W L&R with 22W sub. w

26th October 2009, 11:20 PM	#9
VectorSpace diyAudio Member Join Date: Oct 2009	I'm not really that interested in quality. This is for a school project. I just need to demonstrate that I am splitting the audio spectrum into two separate frequency bands. So what speakers and amps would you guys use to achieve this goal?

27th October 2009, 02:43 AM	#10
Pano diyAudio Moderator Join Date: Oct 2004 Location: North Carolina Blog Entries: 4	It doesn't matter what amps you use, as long as they have "enough" power. And it matters that they have a volume control. The main thing you want to worry about is that you get the gain right. Everything after that is just frosting on the cake.

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