A while ago I had a couple threads going related to making modifications/upgrades to a pair of PSB Image 2B speakers. Here are the links for reference.
Anybody ever modify PSB Image 2Bs? Worth it? What did you do?
Am I interpreting this information correctly? (Tweeter selection problem)
Here is the schematic for the crossover:
The Pos+ wire going to the tweeter is yellow, the Neg- is blue.
One of the mods I made to the speakers was swapping the original tweeters out for some better ones made by Peerless.
When I was replacing the tweeter on the second speaker, I noticed that the OEM tweeter was wired in reverse polarity. Blue to Pos+. I had never removed this tweeter from the cabinet before and it was the OEM PSB tweeter so I assume either the previous owner pulled the tweeter out at some point and wired it backwards when reinstalling it or it could've come from the factory wired that way; either by mistake or on purpose.
I didn't really look at how the tweeter in the first speaker I did the tweeter swap/upgrade on was wired so I don't know how it was wired. I knew from looking at the crossover that the yellow wire was Pos+ and the blue wire was Neg- so I just pulled the wires off it without noting how it was wired and then I wired in the replacement tweeter with yellow to Pos+ and blue to Neg- without giving it a second thought.
So then I get to the second speaker and notice that the tweeter was wired in reverse polarity; Blue to Pos+, Yellow to Neg-. I didn't think to check if the woofer was wired in reverse too in which case the woofer and tweeter would be in phase. I can check tomorrow when I get out to my cabin but if I recall correctly, the woofer has different sized spade terminals for Pos+ and Neg- so it can probably only be wired one way.
I'll know more tomorrow but for now I'd like to know is there a chance the factory/designer could have wanted the tweeters wired out of phase with the woofers? Is there ever ANY reason why you'd deliberately wire the tweeters out of phase with the woofers on 2-way speakers?
Anybody ever modify PSB Image 2Bs? Worth it? What did you do?
Am I interpreting this information correctly? (Tweeter selection problem)
Here is the schematic for the crossover:
The Pos+ wire going to the tweeter is yellow, the Neg- is blue.
One of the mods I made to the speakers was swapping the original tweeters out for some better ones made by Peerless.
When I was replacing the tweeter on the second speaker, I noticed that the OEM tweeter was wired in reverse polarity. Blue to Pos+. I had never removed this tweeter from the cabinet before and it was the OEM PSB tweeter so I assume either the previous owner pulled the tweeter out at some point and wired it backwards when reinstalling it or it could've come from the factory wired that way; either by mistake or on purpose.
I didn't really look at how the tweeter in the first speaker I did the tweeter swap/upgrade on was wired so I don't know how it was wired. I knew from looking at the crossover that the yellow wire was Pos+ and the blue wire was Neg- so I just pulled the wires off it without noting how it was wired and then I wired in the replacement tweeter with yellow to Pos+ and blue to Neg- without giving it a second thought.
So then I get to the second speaker and notice that the tweeter was wired in reverse polarity; Blue to Pos+, Yellow to Neg-. I didn't think to check if the woofer was wired in reverse too in which case the woofer and tweeter would be in phase. I can check tomorrow when I get out to my cabin but if I recall correctly, the woofer has different sized spade terminals for Pos+ and Neg- so it can probably only be wired one way.
I'll know more tomorrow but for now I'd like to know is there a chance the factory/designer could have wanted the tweeters wired out of phase with the woofers? Is there ever ANY reason why you'd deliberately wire the tweeters out of phase with the woofers on 2-way speakers?
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That's often done, depending on which connection makes the response smoother.
Ideally, the tweeter would be wired in-phase for odd order crossovers, and out-of-phase
for even order crossovers.
Yours is a mixed-order, second for the tweeter and third for the woofer, so the connection
that gives smoother response is normally chosen.
Ideally, the tweeter would be wired in-phase for odd order crossovers, and out-of-phase
for even order crossovers.
Yours is a mixed-order, second for the tweeter and third for the woofer, so the connection
that gives smoother response is normally chosen.
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Yes - to get an in-phase response through the crossover region. There's no downside / negative. it's one of the many tools we use to get phase to align.
This may be required for asymmetrical slopes, or even order slopes with a stepped baffle.
It's all about target acoustic slopes too. When people say "LR2 crossovers require one of the drivers to be inverted" - this is assuming the crossover plus driver response = LR2 AND the voice coil centres are aligned.
Basically - looking at a crossover diagram tells you zero about whether one of the drivers should be inverted. It's all about the phase behaviour taking into account the effect the crossover has on the drivers in their enclosure/baffle.
This may be required for asymmetrical slopes, or even order slopes with a stepped baffle.
It's all about target acoustic slopes too. When people say "LR2 crossovers require one of the drivers to be inverted" - this is assuming the crossover plus driver response = LR2 AND the voice coil centres are aligned.
Basically - looking at a crossover diagram tells you zero about whether one of the drivers should be inverted. It's all about the phase behaviour taking into account the effect the crossover has on the drivers in their enclosure/baffle.
The easiest way to determine tweeter orientation is to play a tone at the crossover point. Swap tweeter polarity while tone plays. The correct orientation is when the tone gets louder.
For phase tracking, 2nd, 6th, 10th etc. order crossovers need to have the drivers connected mutually out of phase.
Every order introduces 90 degrees of phase shift. So a third order is 270 degrees out and if it is paired with a 1st order on the woofer being 90 out they will be 180 out relatively. If you invert phase on the tweeter you will be back in phase relatively. There is wiggle room here but use it as a guide. If both are 2nd order they are both in phase relative to each other so no need to invert the tweeter.