Bridging to Components
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Bronze Member Username: CarlbPost Number: 13 Registered: Aug-04 | Would it be okay to Bridge a four channel amp into 2 channels, and then each channel powering a component set (one midrange and tweeter through the crossover for each channel)? Or am I right in assuming that I can only bridge front/rear, and therefore will be mono, and it will sound like crap? |
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Bronze Member Username: StanleycPost Number: 37 Registered: Oct-04 | Hmm, I had the same exact question. Bump to get an answer. =) |
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Gold Member Username: Jonathan_fGA USA Post Number: 2121 Registered: May-04 | You can bridge and be perfectly fine. Just make sure that the front will be a designated channel and the right will be designated. Hook the front channel to the left speaker and the rear channel to the right and you'll be ok. Set the gains correctly between drivers (preferably w/ a voltmeter). It'll sound the same as if the components were hooked up to a two channel amp, but it'll have a bit more distortion and less damping than if the amp were running at 4 ohms non-bridged. |
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Silver Member Username: FishyTamarac, FL USA Post Number: 377 Registered: Sep-04 | Yeah I have an older Xtant 4180C(45 x 4) bridged to a pair of MB Quart 5 1/4" Q's(their "best" 5 1/4's) at 180 x 2. I used to have them running off half the amp at 45 watts each, but since higher end components like these generally tend to be a lil less efficient they were havin a hard time keepin up with 400 watts of bass. The Q's sound slightly "harsher" now but are definitely louder and "punchier". I would have preferred a bigger 2 channel like the 2200ix(100 x 2), but I paid a lot for the 4180c so I figured I oughta just make do. If your amp is capable of producing more power than what your components are rated for in bridged configuration be careful how you set the gains like Jonathan said and you should be cool. -Fishy |
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Bronze Member Username: CarlbPost Number: 14 Registered: Aug-04 | Okay thanks. I'll be sure to match the gains exactly. I bought my 4 channel, and my plans became a little bigger, and just wanted to see if I could reuse the amp or not. My other choice is running a pair of ID 2 ohm components. |
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Silver Member Username: FishyTamarac, FL USA Post Number: 388 Registered: Sep-04 | I don't know what those sound like, but I remember Soundstream came out with some 2 ohm components a while back and they sounded like crap compared to their other 4 ohm versions. Of course they were a different line so they may have just sounded inferior because they were intentionally made "cheaper". -Fishy |
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BasstoMakeEarthquakes Unregistered guest | I could use a little help wiring my system. I have a hifonics brutus 1000 watt amp stable down to one ohm, and 2 12 inch solo baric L7 kickers. I want to bridge to 2 speakers in a 1 ohm load if possible. |
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BasstoMakeEarthquakes Unregistered guest | I could use a little help wiring my system. I have a hifonics brutus 1000 watt amp stable down to one ohm, and 2 12 inch solo baric L7 kickers which are 4 ohm dvc. I want to bridge to 2 speakers in a 1 ohm load if possible. |
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New member Username: XtormPost Number: 2 Registered: Oct-04 | i hav a 4x50w rms blaupunkt velocity amp, i use 2 channel for tweeter n 2 for mid bass with customize x-over (normal x-over dun allowed bi-amp) it sounded alot better then briging! |
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Gold Member Username: Jonathan_fGA USA Post Number: 2152 Registered: May-04 | Biamping works well. An active or digital crossover is generally better than passive would if you're looking to biamp. Good thing about digital is that you eliminate the phase shift that happens with electronic (active and passive) crossovers. |
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Silver Member Username: FishyTamarac, FL USA Post Number: 393 Registered: Sep-04 | Hey Jonathan how much more SPL do you get with say a dedicated 45 watts to each tweeter and midrange(biamped) as opposed to just 45 watts standard? How would that compare to 180 standard? I was thinkin about biamping my Q's(they're set up for it passively) to get a lil better SQ than 4 ch bridged. Was just worried that'd I'd lose to much volume and that it might not be worth the trouble of running another set of wires through my doors to my Xovers. Its a real p i t a. thanks -Fishy |
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Gold Member Username: Jonathan_fGA USA Post Number: 2159 Registered: May-04 | IMO, biamping on a passive crossover is a waste of an amplifier channel. You'll lose a lot of SPL by doing that as you're cutting the power by 1/4. Remember that in your current configuration each component is getting a full 180 watts. Only benefit you'd gain is a little SQ due to running the amp at 4 ohms, and better damping b/c the power supply to each component is isolated and goes to it's own amp channel. With 1/4 of the power, I'd say you'd lose close to 6 db. You'd see more benefit going active or digital that way crossing over is done at low levels, thus no crossover losses. Any power by that amp channel produced above or below the crossover frequency will be burned off as heat in the crossover. Active has more benefit. If you plan to eventually biamp, I'd recommend you consider eventually going active or digital, then you won't have as many losses. Passive crossovers contain capacitors and inductors, and most also have resistors and impedance correction networks, and all eat their fair share of power before it gets to the speakers. Big benefit of active is that you don't lose anything from a passive X-over, plus you can adjust the levels of all components (BIG plus in a car), and you get better damping and more amp headroom. Since all crossing over is done before the amp, the amplifier will only produce the frequency range that comes to it and no losses of producing everything else will be had. Digital is good because you don't have phase shifts like you do with electronic crossovers (passive or active), and with crossovers like the Audiocontrol DXS, you can control the crossover via a dash control module. |
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Bronze Member Username: CarlbPost Number: 15 Registered: Aug-04 | So would I be better off with the ID 2 ohm comps, or with bridging my channels to run to some CDT HD62Z, or Eurosports? |
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Bronze Member Username: CarlbPost Number: 16 Registered: Aug-04 | btw the Amp is an Arc Audio 4050XXK |
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Silver Member Username: FishyTamarac, FL USA Post Number: 402 Registered: Sep-04 | I have the ability to go active with my frx-456 and/or the xtant xovers. You recommend 12 or 24 dB/octave? It'll still only be 45 watts to everything. How much power would I need for the tweets with 180 to the midrange? Probably won't do it but was just wondering. -Fishy |
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Silver Member Username: FishyTamarac, FL USA Post Number: 403 Registered: Sep-04 | I dunno, have you listened to both components? -Fishy |
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Gold Member Username: Jonathan_fGA USA Post Number: 2165 Registered: May-04 | Depends on if the tweets are 4 or 8 ohm and how efficient they are. If the passive crossover uses an Lpad, the tweeters will need less power than the mid. That frx-456 has level control, so all is good. 12 db usually works better for driver blending, but there is a phase shift of 180 degrees, but you can simply wire the tweeter out of phase. 24 db/oct allows better power handling, and there is no phase shift with 24 db/oct(only crossover slope that does this, 48 would be next, etc.) 45 watts active goes further than 45 passive does. Being Quarts, I'm sure they had a pretty power hungry crossover b/c of all the circuitry used. Plus, the amps will put out more power. I'd still say it'll be quieter than the bridged, but less so that if you had them on a passive crossover. Haven't really tested to see how much louder active is over passive, but I'd say it'd get possibly 2-3 db louder than a passive with the same power. Oh well, you already have the components to do it with, what's the harm in trying, right? About that passive crossover, if you don't like active, you can still biwire to the passive crossover, and run those wires to the same bridged terminal of the amp. It won't change impedance, so your amp will be safe. It will in theory isolate each component from the other, meaning one driver has less chance of interfering with the other from back EMF. |
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Silver Member Username: FishyTamarac, FL USA Post Number: 408 Registered: Sep-04 | I didn't know about that 180 degree phase shift thing. I thought that only worked for passive. Why can't they just invert the signal in the crossover. I guess you can't just reverse polarity because that would leave your "signal" unshielded in the RCA's but why not internally? or is that what those PPI phase inevrters you were talking about do. Come to think of it. If I remember correctly, doesn't that 180 degree phase shift only occur at the crossover point and gradually changes with frequency? or am I digging up things from my past that aren't there. Man, I aced all the Acoustics courses I took, but when I opened up a textbook today to try and figure out time delay I was totally lost. I think my brain's gettin old. -Fishy |
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Silver Member Username: FishyTamarac, FL USA Post Number: 409 Registered: Sep-04 | Oh the Q's don't have what I know as an L-pad, but they do have 3 or 4 jumper positions in -2dB increments and are bright as hell at 0 dB. My B&W DM 602's are just the opposite. They're 8 ohm speaks with 4 ohm tweets in em. wierd -Fishy |
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Gold Member Username: Jonathan_fGA USA Post Number: 2168 Registered: May-04 | Any electronic crossover introduces a phase shift because of the components used, except 24db/oct units. It's not an acoustic phase shift, it's electronic, there's a difference. Inductors and capacitors introduce a phase shift in a circuit, it doesn't change above or below the crossover frequency, the only difference is that above or below the crossover frequency, their impedance increases. The phase shift remains the same, but it also introduces a time delay, and that time delay is what varies with frequency. An acoustic phase shift is different, it varies with frequency, and it is what makes the sound you hear. If you made the acoustic phase totally flat, music would sound like one droning lifeless blended tone. |
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Gold Member Username: Jonathan_fGA USA Post Number: 2170 Registered: May-04 | Oh, and if they're bright, you'll have to turn their level down (or give them less power) definately. |
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Silver Member Username: FishyTamarac, FL USA Post Number: 420 Registered: Sep-04 | But 25 Class A watts wouldn't be able to keep up with 180 right? And where does the phase shift in an active xover come from? Is it part of how the opamp itself operates? or does it come from the capacitance in the feedback loop? -Fishy |
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New member Username: XtormPost Number: 3 Registered: Oct-04 | hmmm......so now i'm using the amp to high pass with 12db slope, then to a 6db passive x-over, does it add up to 18db slope? do i hav to invert the tweeter? no money yet to run active, dun wan to spemd money on low end stuff to make more damage then runing passive at a way cheaper cost |
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Gold Member Username: Jonathan_fGA USA Post Number: 2177 Registered: May-04 | Active electronic crossover works in the same way that a passive does, only difference is inductors etc. are variable. It's just done at low levels. Digital eliminates that problem. Phase shift simply comes from the capacitors and inductors. It's really the least you should worry about with a crossover. You can make it work by either wiring out of phase or changing component location. IF the high pass of the amp is at the passive x-over point, you have an 18db/oct slope. Stay w/ passive if that's the case above. An 18 db/oct slope has a 270 degree phase shift. |
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Silver Member Username: FishyTamarac, FL USA Post Number: 422 Registered: Sep-04 | Active electronic crossover works in the same way that a passive does, only difference is inductors etc. are variable. Ok, I'm really confused now. I thought an active crossover utilized opamps with an RC feedback loop do determine crossover point. Changing SIP's or adjusting a pot simply changes the resistance in that RC circuit which changes the xover frequency. http://ele.tut.fi/~troh/filter.pdf How is that analogous to the way a passive RLC circuit works? and wouldn't you just cascade two of these 12 dB guys together to get a 24 dB slope? I never understood the difference between a Butterworth and a Linkwitz-Rilely filter. My frx-456 uses L-R but my Xtants use Butterworths. http://kahuna.sdsu.edu/~tucker/diyaudio/xover.html --Fishy |
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Gold Member Username: Jonathan_fGA USA Post Number: 2188 Registered: May-04 | Oops, forgot they don't use inductors, it's strictly capacitors. For some stupid reason I was thinking they used variable inductors. Yep, it's an RC circuit that changes freq.. Diff. in Butterworth and Linkwitz Riley is that Butterworth gives a 3 db peak at the crossover frequency, while the Linkwitz Riley uses a Bessel Filter that dampens more around at the crossover freq.. Good thing about active is you can use 24 db oct w/o the losses it has in a passive network. |
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Gold Member Username: Jonathan_fGA USA Post Number: 2189 Registered: May-04 | The more I look at myself, the more I realize how much my knowledge of electronics has crapped out on me in the last 7 years lol. These days when I go to work and look at old schematics I'd made when I was fresh out of school, my jaw kinda drops and I think "I actually drew that up?". I guess 7 years out of action doesn't help. I'll become the next Billy Madison if I don't catch up sooner or later  . |
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Silver Member Username: FishyTamarac, FL USA Post Number: 436 Registered: Sep-04 | You think you're in bad shape. I was pulling a 4.0 at FAU for a while in Ocean Engineeering. I got frustrated when I finally got to my Senior year(takes a while going part time :P) and took some time off hoping to finish later. I was driving a party boat at the time having a blast. I told myself that I ought to enjoy life while I could. Well its been ten years now and I'm not doin the party boat thing and am thinking about going back to School, but after opening up my Acoustics text the other day I'm beginning to wonder. I said to myself "You actually used to understand this math?" All I remember are the generalities, no equations(had to look up P=IV, lol), just a few basic principles. If I go back to school now I'm just about gonna haveta start all over. Maybe I'll open a stereo shop, just no Audiobahn. -Fishy |
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Gold Member Username: Jonathan_fGA USA Post Number: 2191 Registered: May-04 | It would have been nice if my high school banged important stuff like that in my head instead of absolute useless crap. I mean, I use electronics and math everyday, but I'll never have to diagram a friggin sentence unless some disturbed english teacher holds a gun to my head and decides that is what is going to decide my fate . |
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