more power/better damping if bi-amp?
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=104581
Printed Date: May 10, 2024 at 2:36 AM
Topic: more power/better damping if bi-amp?
Posted By: jmelton86
Subject: more power/better damping if bi-amp?
Date Posted: May 08, 2008 at 6:18 PM
Hello, I recently upgraded my front-stage amp from a ClarionProAudioAPA-2104 to an AlpineMRP-F240. First off, this amp sounds MUCH cleaner and gives me a little more volume over the Clarion -also got rid of alternator whine = yea! El Oh El. I guess it is more efficient. I am using passive x-overs for both my tweeters and mid-woofers, so technically each driver is recieving about 20watts (4ohm load per channel = 40watts per) because I am only using the front channel outputs from the amp. *Only using front pre-amp outputs from HU at this time. If I bi-wire my components, I'll use the front pre-amp outputs for tweeters, rear pre-amp outputs for mid-woofers. What I want to know is, other than more time-delay flexibility [would be using 4channels (1driver per channel) VS 2channels (2drivers per channel)], would each driver get twice the power? I'm thinking not, as I am using passives. Like afor mentioned, I am mainly wanting to do this because of better time-delay capabilities but, I wouldn't mind the extra power. Will they get more power? Thank you for looking, Javin. ------------- 2013 Kia Rio -90a alternator
DDX470HD GTO14001 GTO1014D (x3)
Big3 in 1/0G
1/0G to GTO14001
Replies:
Posted By: stevdart
Date Posted: May 08, 2008 at 7:09 PM
You should just consider the amount of power at the crossover input; you really don't know how much of it is going to each driver at any time. Power distribution, by frequency, should look like this chart shows (from Rod Elliott's ESP site): 
Where, at 250 Hz the LP is getting 40% of the amplifier's available power at that frequency while the HP gets 60%. At 3000 Hz the LP is getting 85% of the amp's available power at that frequency. See section 7.0 Determining Power Losses. You may not be able to find what the amplifier's power output should be per frequency. Edit: Wait....now let me get this straight. You said you have a filter on each driver, and each driver is driven by a channel. So, the power is what it is per channel according to the amplifier specs. Use that power number and scale it to the percentage shown in the chart. ------------- Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
Posted By: jmelton86
Date Posted: May 08, 2008 at 7:46 PM
Yes, each driver has its' own passive filter. The tweeters are h/p'd at 4000Hz, and the midwoofers are l/p'd at 3500Hz -as per Haemphyst-of-fury. Cool. As of right now, I have the left-side tweeter and midwoofer driven by the front-left output channel from the amp, and the right tweeter/mid driven by the front-right output channel. -Rear channels are unused. I was wondering if I was to bi-amp the speakers (tweeters driven by front channels, midwoofers driven by rear channels), if they would each be getting more power. ------------- 2013 Kia Rio -90a alternator
DDX470HD GTO14001 GTO1014D (x3)
Big3 in 1/0G
1/0G to GTO14001
Posted By: haemphyst
Date Posted: May 08, 2008 at 9:13 PM
The dynamic power would be greater... i.e. the amount of power on tap. SIGNIFICANTLY more dynamic power for the tweeter than the mid, but more for both.
:::::EDIT:::::
Scratch that... Follow stevdart's info above. If ACTIVELY crossing over, my info applies.
-------------
It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: jmelton86
Date Posted: May 08, 2008 at 9:17 PM
haemphyst wrote:
The dynamic power would be greater... i.e. the amount of power on tap. SIGNIFICANTLY more dynamic power for the tweeter than the mid, but more for both. For a given SPL, the amount of power each driver receives, will be the same, either 2 channel or 4 channel amplified.
Thanks, Haemphyst-of-fury! Question; i'll be using the hpf on the midwoofers. Should I on the tweeters even though they already have passives? *Holy-crap, stevdart! That ESP link you gave is nice! ------------- 2013 Kia Rio -90a alternator
DDX470HD GTO14001 GTO1014D (x3)
Big3 in 1/0G
1/0G to GTO14001
Posted By: stevdart
Date Posted: May 08, 2008 at 10:30 PM
The impedance will vary throughout the freq range of each driver, so even if you have employed all drivers with 4 ohm nominal impedance, the filtered results will be ranging. I'll post up a couple of file pics to show how impedance varies, using a crossover simulation that I've been working on for my home mains. withplmids2008.jpg withplmidschart2008.jpg mains_impedance2008.jpg While this is a 3-way crossover, it can be used to illustrate what will likely occur with your setup as well. The mids are series-wired 8 ohm drivers (16 ohms) and the tweeter is an 8 ohm nominal (5.8 Re) driver. The low pass for the mids is a 12 db second order and the high pass for the tweeter is an 18 db 3rd order. The actual crossover occurs at about 3100 Hz. Looking at the response chart: the mids are audible for a range of about 200 Hz to 7500 Hz. Even though their nominal impedance is 16 ohms, the modeled response ranges from about 6.6 ohms to about 11.2 ohms. The tweeter is 8 ohm nominal driver, but the response proves that it will range from 11.2 ohms to 6.8 ohms. (Speaker Workshop is used for this modeling.) This is all illustrative to make the point that it is not worth considering whether each driver will get more power alone on a channel than when sharing it with another driver in a different freq range. Either way, it is nigh impossible to foretell how much power is actually going to be applied in real-life music playing. Just consider the biamping route a plus for the additional tweaking it will enable you to do. A 40 watt-per-channel (at 4 ohms) amplifer is certainly appropriate for mids and tweeter duty no matter where their perspective impedances may range to. ------------- Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
Posted By: jmelton86
Date Posted: May 08, 2008 at 10:41 PM
stevdart wrote:
Either way, it is nigh impossible to foretell how much power is actually going to be applied in real-life music playing. Just consider the biamping route a plus for the additional tweaking it will enable you to do.
Awesome! Thanks for the resources! ------------- 2013 Kia Rio -90a alternator
DDX470HD GTO14001 GTO1014D (x3)
Big3 in 1/0G
1/0G to GTO14001
Posted By: stevdart
Date Posted: May 08, 2008 at 11:26 PM
Oops, I forgot your question: jmelton wrote:
Question; i'll be using the hpf on the midwoofers. Should I on the tweeters even though they already have passives?
No. Or if you have to select the filter, set it as low as it will go...below the range of the driver. You don't want the active filter interfering with the passive high pass. ------------- Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
Posted By: jmelton86
Date Posted: May 08, 2008 at 11:47 PM
Cool. Just wanted to be sure.  ------------- 2013 Kia Rio -90a alternator
DDX470HD GTO14001 GTO1014D (x3)
Big3 in 1/0G
1/0G to GTO14001
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