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Discussion Starter #1
Hi,

I have Boston Pro60SEs at the front, tweeters at top of door and Woofers at the bottom. I also have Boston SR60 comps in the rear, same setup tweeters high, woofers low. Currently running off 2 JL Slash 300/2 amps.

I have a bit one to install and am looking to get my T/A sorted as best as possible. I have an unused JL HD900/5 I can pretty much do a straight trade for an HD600/4.

I'm thinking of running the Pro60s bi-amped from the HD600/4, and one of the slash 300/2s to drive the rears, all through the bit one.

There doesn't appear to be much on the Boston datasheets/manuals about bi-amping..

They are rated at 120W/ch (though they don't have any problem putting 150W into them) and 3 Ohms. How does this change when bi-amping? Will each of the passive xovers be seen as 3 Ohm and still take 120W? My feeling is not. How does this normally work?

Also as a side note.. If I time align my front tweets and woofers, how much will time aligning the rear comps as single speakers make a difference to the stereo image? What is normally done for "rear fills". Should I be bandpassing from my bit one to the rear comps to minimise the image being dragged towards the rear?

I can't mount the SR60s as co-axials so they are stuck in the positions they are in.

Cheers!
 

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Also as a side note.. If I time align my front tweets and woofers, how much will time aligning the rear comps as single speakers make a difference to the stereo image? What is normally done for "rear fills". Should I be bandpassing from my bit one to the rear comps to minimise the image being dragged towards the rear?
I don't think the rear speakers should be time aligned with fronts. Shouldn't this draw sound stage back? There are many options for rear fill, depending on equipment:

1. Simply attenuated or turned off rear speakers.
2. Time delayed (by about 20ms) and attenuated left and right speakers.
3. Same as above, band passed between 300-3000Hz.
4. Same as above, but the speakers are playing the difference signal (the component of signal that's common to both speakers is removed).

The logic behind delaying speaker signal is to produce the effect of sounds reflecting off the rear wall in a room. Bandpass is to remove high frequency sounds which may draw sound stage back. The difference signal lacks much of human vocals because they're centered, and therefore removed, leaving only "ambiance" sounds.
 

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Discussion Starter #3
Thanks for the reply. I guess I'll just have to play with the rears until I'm satisifed using those ideas.

What about the Impedance when bi-amping?

Cheers
 

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The tweeters don't need (won't take) near as much power as the woofers so if your amps aren't set in stone you can use a smaller amp for the tweets.

As for how much the Pro60SE's can take, you might try a search because I recall several guys with systems putting a ton of power to them claiming that it really wakes them up. I just can't remember the wattage they were using.
 

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Discussion Starter #5
So I'll be pretty safe putting 150W (set with DMM) into the tweeters through the passive crossovers, and as much juice as possible from a bridged 600/4 to the woofers? I'm guessing I won't be able to get near 300W onto them without upsetting the balance between woofer and tweets..
 

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I would guess the same rms for the woofer and smaller amp for tweeters. I ran a lot of systems on 30rms/ch on tweeters but that was old school 12v rated amps.

I have some older boston comps and ran 4x50/70/75 on them, then dropped this 4x125 Kappa class D on them and they did sound nicer at high outputs for sure. They seem to have no problem at 125rms likely could take more. I also think they are not the most efficient and that is why 75rms was not that loud on them and I pushed it at times. But 125 is enough for me I am happy at this level.

I run some alpine coax for rears and the front comps are mounted closely with the tweet and woofer the same distance to ear, and they are passive. So I set the TA by distance and then fudge it by ear some, but doubt it is dialed in perfect yet and plan more changes anyway. Really the front and rears are not much difference in distance in this car. Also keep the rears significantly lower volume so they don't pull the stage back too much, but they pull it back a little to give me more of a left side. The TA can do it without the rears, but I like rears and have passengers plus the rears are mounted recessed so you don't get much high end in the front. I find an install like that really helps the rears, then you have full range in back for passengers or out of car listening...but they put out some midbass/mid to the front or to help the front. If you like it, is up to you.

The Bostons I have use that inverted dome tweeter and are rated for 250rms or some such huge number.
 
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