Another stupid question! - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 15th May 2007, 06:54 AM   #1
Dxvideo is offline Dxvideo  Turkey
diyAudio Member
 
Dxvideo's Avatar
 
Join Date: Nov 2003
Location: Turkey
Send a message via Yahoo to Dxvideo
Default Another stupid question!

If I make two way active speaker system with LM4780 and give him +/-35v power (that enough to drive 60W for 8 ohm loadfs)
That system will give 120W or 60W in total. So I can call it a 120W active speaker or 60W?

Thanks in advance..
__________________
Best regards,
Ozgur
  Reply With Quote
Old 15th May 2007, 07:05 AM   #2
tade is offline tade  United States
diyAudio Member
 
Join Date: Feb 2005
Location: Ralieigh nc
Send a message via AIM to tade
because the crossover's job is to split power at a certain frequency, you cannot add the power, however you will see a benefit because both amps will share the load. The system will never take more than sixty watts.
  Reply With Quote
Old 15th May 2007, 07:07 AM   #3
Dxvideo is offline Dxvideo  Turkey
diyAudio Member
 
Dxvideo's Avatar
 
Join Date: Nov 2003
Location: Turkey
Send a message via Yahoo to Dxvideo
Ok tade, thanks a lot.
This is what I exactly needed.
__________________
Best regards,
Ozgur
  Reply With Quote
Old 19th May 2007, 12:10 PM   #4
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi,
your active 60+60W speaker will sound louder than a 60W passive speaker.
It may sound as loud as a 100W amp driving a passive crossover using the same drivers.
It may even sound louder than 120W into those passively crossed drivers.
At these very high levels the active version will sound cleaner due to the lack of (or reduced) clipping in the respective amplifiers.
__________________
regards Andrew T.
  Reply With Quote
Old 19th May 2007, 12:49 PM   #5
Dxvideo is offline Dxvideo  Turkey
diyAudio Member
 
Dxvideo's Avatar
 
Join Date: Nov 2003
Location: Turkey
Send a message via Yahoo to Dxvideo
So the total power will be 60W theory is wrong?
I am confused! I agree with your "clear sound" theorem. However if we filter the signals by hi and low frequencies then;
If total signal is at level x,
If we pick up some frequencies (y) from inside that x,
If we pick up the other frequencies (z) from inside also that x
The total x will never changed. And y+z will always gives x. So our final signal will be equal to x.
So if you split or not split the signal; the result will never changed. You can take it like bi-wiring. When you connect your speakers as biwired then the total rms output will change or not?
This is my opinion. May be I am mistaken.
__________________
Best regards,
Ozgur
  Reply With Quote
Old 19th May 2007, 04:32 PM   #6
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi,
you will have an
Quote:
active 60+60W speaker
Beyond that is guesswork when trying to compare it to passive speakers.

But let's examine a few bits of guesswork.

Assume one frequency passing from source to your ears.
Let's put out 60W @ 200Hz. Send this to the active speaker and you get the SPL due to 60W. Send the same 60W to a passive crossover, the SPL (from the same driver) will be marginally lower due to the crossover components and the longer cables.
Similarly a high frequency signal @ 1kHz will be marginally louder from the active driver than from the passive driver.

Now consider two frequencies in the signal, one frequency passing to each driver. Let's suppose they are equal in magnitude. That 60W signal passing to bass speaker will produce the same SPL as the single frequency case. Similarly that high frequency signal will be the same as the single frequency case. The resulting output from the two speakers will be the sum of two 60W SPLs arriving at your ears.

Now consider what happens to the passive system with two frequencies each split by the crossover and sent to their respective drivers.
The 60W signal is a 31Vpk signal. Each frequency is of equal magnitude and so each frequency is half of that voltage. This means that 15.5Vpk from each of the two frequencies forming the total signal just reaches the clipping voltage of the 60W amplifier.
The resulting signal coming from the passive crossover is 15W less the losses in the crossover. It appears that each signal is 6db down from the active case. They then add again in the air to arrive at your ear still 6db (+ a bit) down from the active case.

This a somewhat simplistic analysis but it does show that active speakers can, when processing complex signals, sound a lot louder than passive speakers using the same drivers. The first thing to realise in this simple analysis is that each of the drivers cannot take the same power as when combined into a passive system. In a two way, the bass/mid may take 50W and the treble just 5W but when combined with a crossover could be (correctly) specified as a 60W speaker. But the active system is more likely to be a 50W + 20W active system. Even this will play complex signals louder than the 60W system. And it has the benefit of double the voltage drive into the treble speaker to avoid clipping in the treble amp. The active 50W+20W will play single frequencies at about the same SPL as the passive system.
__________________
regards Andrew T.
  Reply With Quote
Old 20th May 2007, 03:39 PM   #7
diyAudio Member
 
Join Date: Jan 2006
Location: Fairmount, GA
BUT!!! The Watt police will not come and get you if you tell your friends you have 120W per channel!
__________________
Poor stereo mix? Switch to mono! Perfect.
  Reply With Quote
Old 20th May 2007, 03:46 PM   #8
Hartono is offline Hartono  Indonesia
diyAudio Member
 
Join Date: Nov 2002
Location: currently in China
2 x 60 watt amplifier per speaker (60W for tweeter+60W for woofer)
total 120 watt amplification per speaker.

I think above is suitable for sale documentation.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Stupid question Leolabs Everything Else 2 8th July 2006 02:09 AM
ok, stupid question probably the-eliti Multi-Way 6 23rd January 2002 04:17 AM


New To Site? Need Help?

All times are GMT. The time now is 05:35 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2