Bridging components
07-25-2006, 05:36 AM
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Bridging components
I have some MB Quart QSD 6.5s running the front stage in my Z. From what I am reading, they are 4ohm. My amp is stable to 2 ohm stereo, so if I bridge the mid and tweet on each crossover, and set it to bi-amp mode, will this give me a 2ohm load? I'm wondering b/c the mid says that it is 4ohm, the tweeter says 6ohm. If I do not run it bi-amped, are the crossovers already set up to bridge the two channels? I'm guessing that if it's switched to a non-bi-amped mode that this is the case, am I correct? I know that I have probably already answered my question, but I need some reassurance before I accidentally screw up my system.
07-25-2006, 06:25 AM
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Yikes!
Don't be shorting out parts in your crossover looking to lower your output impedance! You can not connect the midranges and tweeters together. Well technically you can but you'll screw up the sound and possibly smoke the tweeter.
The crossover is there for more than looks, it ought to be a carefully engineered part of your speaker system.
A properly built crossover is designed to present a load impedance to your amplifiers and to direct/channel/filter the proper frequencies to the proper driver. The reason we have woofers, midranges and tweeters is that they each have a limit to the range of sound that they can reproduce. A proper engineer is going to take those speaker drivers and carefully craft the crossover to blend them together. There is as much of the sound "in" the crossovers' design as in the speaker placement, and driver design.
Do you really understand why you want to connect a 2 ohm load to your amplifier vice a 4 ohm one? You're typically looking at 3dB difference, likely less than that. My amps give me +115 dB easy which means much pain and ringing in the ears for hours and hours ... adding 3 dB would just double the hearing damage. 3 dB is just barely noticeable, some home stereo receivers have their volume controls with 3 dB steps between volume control “clicks”.
Have you ever seen an impedance plotting of a typical set of speakers? They vary all over the place as the crossover and speaker elements present a different impedance back to the amplifier as frequency changes. Circuits with inductance and capacitance very their respective impedance as frequency changes. A speaker rated at 4 ohms is just 4 ohms for a very small portion of its range.
I would leave speaker crossover designing and modification alone for now.
In a true bi-amp situation you have seperate amplifers and bandpass crossovers for each set of speakers. Do your current crossovers accept a bi-amp input with modification like removing a jumper? If so this is the ideal way to get that 3 dB increase in sound you're seeking. You could run seperate amplifiers to each speaker thru the bi-amp capable crossover. Of couse that's going to double the cost of your amplifiers but it will give you one more "click" on that volume control.
Be careful with your hearing as once you have tinnitus (ringing in the ears) it's forever. Practice safe sound.
Don't be shorting out parts in your crossover looking to lower your output impedance! You can not connect the midranges and tweeters together. Well technically you can but you'll screw up the sound and possibly smoke the tweeter.
The crossover is there for more than looks, it ought to be a carefully engineered part of your speaker system.
A properly built crossover is designed to present a load impedance to your amplifiers and to direct/channel/filter the proper frequencies to the proper driver. The reason we have woofers, midranges and tweeters is that they each have a limit to the range of sound that they can reproduce. A proper engineer is going to take those speaker drivers and carefully craft the crossover to blend them together. There is as much of the sound "in" the crossovers' design as in the speaker placement, and driver design.
Do you really understand why you want to connect a 2 ohm load to your amplifier vice a 4 ohm one? You're typically looking at 3dB difference, likely less than that. My amps give me +115 dB easy which means much pain and ringing in the ears for hours and hours ... adding 3 dB would just double the hearing damage. 3 dB is just barely noticeable, some home stereo receivers have their volume controls with 3 dB steps between volume control “clicks”.
Have you ever seen an impedance plotting of a typical set of speakers? They vary all over the place as the crossover and speaker elements present a different impedance back to the amplifier as frequency changes. Circuits with inductance and capacitance very their respective impedance as frequency changes. A speaker rated at 4 ohms is just 4 ohms for a very small portion of its range.
I would leave speaker crossover designing and modification alone for now.
In a true bi-amp situation you have seperate amplifers and bandpass crossovers for each set of speakers. Do your current crossovers accept a bi-amp input with modification like removing a jumper? If so this is the ideal way to get that 3 dB increase in sound you're seeking. You could run seperate amplifiers to each speaker thru the bi-amp capable crossover. Of couse that's going to double the cost of your amplifiers but it will give you one more "click" on that volume control.
Be careful with your hearing as once you have tinnitus (ringing in the ears) it's forever. Practice safe sound.
07-26-2006, 09:11 AM
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Originally Posted by Paul350Z
Yikes!
Don't be shorting out parts in your crossover looking to lower your output impedance! You can not connect the midranges and tweeters together. Well technically you can but you'll screw up the sound and possibly smoke the tweeter.
The crossover is there for more than looks, it ought to be a carefully engineered part of your speaker system.
A properly built crossover is designed to present a load impedance to your amplifiers and to direct/channel/filter the proper frequencies to the proper driver. The reason we have woofers, midranges and tweeters is that they each have a limit to the range of sound that they can reproduce. A proper engineer is going to take those speaker drivers and carefully craft the crossover to blend them together. There is as much of the sound "in" the crossovers' design as in the speaker placement, and driver design.
Do you really understand why you want to connect a 2 ohm load to your amplifier vice a 4 ohm one? You're typically looking at 3dB difference, likely less than that. My amps give me +115 dB easy which means much pain and ringing in the ears for hours and hours ... adding 3 dB would just double the hearing damage. 3 dB is just barely noticeable, some home stereo receivers have their volume controls with 3 dB steps between volume control “clicks”.
Have you ever seen an impedance plotting of a typical set of speakers? They vary all over the place as the crossover and speaker elements present a different impedance back to the amplifier as frequency changes. Circuits with inductance and capacitance very their respective impedance as frequency changes. A speaker rated at 4 ohms is just 4 ohms for a very small portion of its range.
I would leave speaker crossover designing and modification alone for now.
In a true bi-amp situation you have seperate amplifers and bandpass crossovers for each set of speakers. Do your current crossovers accept a bi-amp input with modification like removing a jumper? If so this is the ideal way to get that 3 dB increase in sound you're seeking. You could run seperate amplifiers to each speaker thru the bi-amp capable crossover. Of couse that's going to double the cost of your amplifiers but it will give you one more "click" on that volume control.
Be careful with your hearing as once you have tinnitus (ringing in the ears) it's forever. Practice safe sound.
Don't be shorting out parts in your crossover looking to lower your output impedance! You can not connect the midranges and tweeters together. Well technically you can but you'll screw up the sound and possibly smoke the tweeter.
The crossover is there for more than looks, it ought to be a carefully engineered part of your speaker system.
A properly built crossover is designed to present a load impedance to your amplifiers and to direct/channel/filter the proper frequencies to the proper driver. The reason we have woofers, midranges and tweeters is that they each have a limit to the range of sound that they can reproduce. A proper engineer is going to take those speaker drivers and carefully craft the crossover to blend them together. There is as much of the sound "in" the crossovers' design as in the speaker placement, and driver design.
Do you really understand why you want to connect a 2 ohm load to your amplifier vice a 4 ohm one? You're typically looking at 3dB difference, likely less than that. My amps give me +115 dB easy which means much pain and ringing in the ears for hours and hours ... adding 3 dB would just double the hearing damage. 3 dB is just barely noticeable, some home stereo receivers have their volume controls with 3 dB steps between volume control “clicks”.
Have you ever seen an impedance plotting of a typical set of speakers? They vary all over the place as the crossover and speaker elements present a different impedance back to the amplifier as frequency changes. Circuits with inductance and capacitance very their respective impedance as frequency changes. A speaker rated at 4 ohms is just 4 ohms for a very small portion of its range.
I would leave speaker crossover designing and modification alone for now.
In a true bi-amp situation you have seperate amplifers and bandpass crossovers for each set of speakers. Do your current crossovers accept a bi-amp input with modification like removing a jumper? If so this is the ideal way to get that 3 dB increase in sound you're seeking. You could run seperate amplifiers to each speaker thru the bi-amp capable crossover. Of couse that's going to double the cost of your amplifiers but it will give you one more "click" on that volume control.
Be careful with your hearing as once you have tinnitus (ringing in the ears) it's forever. Practice safe sound.
I was going to bridge the output before the crossover, so that it would drop the impedance and I would get 75 watts per channel, instead of 35 watts. It's more for clarity at higher volumes than just making it loud. The speakers are rated 75 watts RMS, so I want to maximize their available power. By bridging it before the crossover, it would not alter the sound b/c the channels haven't been filtered yet.
The setup is designed so that you can add another midbass piggybacked to the other 6.5. I'm guessing that by adding another 4ohm midbass that you can make the total impedence of the network 2 or 8 ohm, depending if it's parallel or in series. (I'm assuming here since I'm not a professional installer)
07-26-2006, 09:29 AM
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Ok ... here goes.
The speaker is rated at 75W .. meaning it has been tested to have the thermal capacity/dissapation to withstand 100hours of 75W RMS or 17.3Vrms of unfiltered pink noise with a 9dB crest factor ... and it will come out in one piece. It in no way means that you will get clean output or never see any power compression in the speaker.
Driving it at that level is just asking for problems, as most all car stereo amp can put out well more than thier rated output on transients and such ...
On to your question ...
If you bi-amp the speakers .. you will see a 4ohm impedance on the bottom end ... and (depending on the XO topology) a 4-6ohm impedance on the top end.
If you have the spare amplifier channels .. run it bi-amp ... using the XO to do so. ... do not connect individual speaker directly to the amp without the XO.
If you run them through the crossover, you will still see the 4ohm-ish load, since the crossover splits the frequencies and the amp only see a certain speaker for certain frequencies. see wikipedia's attached pic.
The speaker is rated at 75W .. meaning it has been tested to have the thermal capacity/dissapation to withstand 100hours of 75W RMS or 17.3Vrms of unfiltered pink noise with a 9dB crest factor ... and it will come out in one piece. It in no way means that you will get clean output or never see any power compression in the speaker.
Driving it at that level is just asking for problems, as most all car stereo amp can put out well more than thier rated output on transients and such ...
On to your question ...
If you bi-amp the speakers .. you will see a 4ohm impedance on the bottom end ... and (depending on the XO topology) a 4-6ohm impedance on the top end.
If you have the spare amplifier channels .. run it bi-amp ... using the XO to do so. ... do not connect individual speaker directly to the amp without the XO.
If you run them through the crossover, you will still see the 4ohm-ish load, since the crossover splits the frequencies and the amp only see a certain speaker for certain frequencies. see wikipedia's attached pic.
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