Not what I meant, a bit too fast in typing I guess. Look in this graph. Phase is not selected. Only the generated minimum phase. I'd like to see that phase curve.
I meant tick, not thick. As in tick a box to show phase.
Same for the tweeter Fr curve. With the phase curve shown, not minimum phase but measured phase.
Sorry for the confusion. Hope you'll be allright trough the storm.
Hi Wesayso ! Very nice, your ongoing forum support...we all keep on learning from it ...
Wish I could help more, but I just can't seem to learn to speak REW...too complicated for my poor mellon
Sorry to post to a post, but I'm past the edit period and see I screwed up the delay recommendation.
I gave a full cycle at about 2600Hz, meant to give a half-cycle or about 0.2ms.
Delay after inversion could end up being just the time difference between pos and neg peaks as shown in REW.....but my strong guess is somewhere in between there and a half cycle (to get both magnitude summation and alignment)
Anyway, like I said one post up...I'm not so good with REW....
Not what I meant, a bit too fast in typing I guess. Look in this graph. Phase is not selected. Only the generated minimum phase. I'd like to see that phase curve.
I meant tick, not thick
Same for the tweeter Fr curve. With the phase curve shown, not minimum phase but measured phase.
Sorry for the confusion. Hope you'll be allright trough the storm.
Thanks, I'm still alive
. Storm calmed down but still snowing. All the way through till 3pm-5pm tomorrow. It's not too bad. About 1ft only. If the storm dumps 3ft of snow at once, that's serious. Had that before. It's worse when it continues. One day, 3ft, next round, 2ft and it goes on. Right now, at where I am, this storm is mild. My trees didn't snap.
Speaker Phase
Tweeter Phase
I have no idea. I'm new to REW. I did measure time arrival using REW delay feature and it says woofer and tweeter arrived at the same time - no delay. I don't know whether one can read time delay with Impulse Response.
You are absolutely correct. That's exactly what I did with this speaker. But that doesn't mean their acoustic centers are aligned vertically. Just closer together.
It all started in 2010 when I was exploring the concept of a DCR (Dual Chamber Reflex). I took the opportunity to test out some new drivers at the same time (kill two birds with one stone). For the life of me, I could never cross the Dayton RS180s with the Seas 27TDFC tweeter properly. No matter what I did, there was always cancellation at the crossover region. I deduced that the acoustic centers are too far apart.
Seven years later, I decided to have another look. Instead of using a step, I tried it with a tweeter with a waveguide, the Peerless H26TG45. And it worked. With the acoustic centers nearer, I can phase align the woofer and the tweeter. Then, it's the next step, what about the time-delay. The arrival time of the tweeter and the woofer. Reason being that though the crossover is in phase, a time-delay can exist. With REW, I measured no time delay, which means it is not only phase aligned but time-aligned.
These are the Impulse Responses of the woofer with the LP filter (yellow) and the tweeter with the HP filter (green).
Hi mark
I don't have any DSP. The only delays I have are from analog crossovers for pa use. But those delays are for woofers. No provision for tweeter delay because in pa speakers, the compression driver is usually behind the woofer.
These are the Impulse Responses of the woofer with the LP filter (yellow) and the tweeter with the HP filter (green).
Hi mark
I don't have any DSP. The only delays I have are from analog crossovers for pa use. But those delays are for woofers. No provision for tweeter delay because in pa speakers, the compression driver is usually behind the woofer.
Hi Michael, humm...need to figure out some way to invert and delay the tweeter.
It looks like that is the mis-alignment your plots are showing..
JBL 4430
The JBL4430 was very successful during it's time. When I was exploring the concept of time alignment, I chanced upon their brochure. What I saw left me confused. Even though they did not they claim the speaker was Time-Alignment, they showed a diagram that suggest Time-Alignment. The implication is since the acoustic centers of the two drivers are aligned vertically, therefore this is a time-aligned speaker. They even have a line at the end of the magnets to signify acoustic alignment.
I have a problem accepting this. Supposing the acoustic centers are actually aligned vertically, does that mean the sound from the woofer and the sound from the tweeter will reach the mic at the same time. I don't think so. Because the low pass filter at the woofer will introduce a delay. Same for the high pass filter at the tweeter. Worse still, the delays are in opposite directions. One lag, the other lead.
Am I right or wrong.
The JBL4430 was very successful during it's time. When I was exploring the concept of time alignment, I chanced upon their brochure. What I saw left me confused. Even though they did not they claim the speaker was Time-Alignment, they showed a diagram that suggest Time-Alignment. The implication is since the acoustic centers of the two drivers are aligned vertically, therefore this is a time-aligned speaker. They even have a line at the end of the magnets to signify acoustic alignment.
I have a problem accepting this. Supposing the acoustic centers are actually aligned vertically, does that mean the sound from the woofer and the sound from the tweeter will reach the mic at the same time. I don't think so. Because the low pass filter at the woofer will introduce a delay. Same for the high pass filter at the tweeter. Worse still, the delays are in opposite directions. One lag, the other lead.
Am I right or wrong.
They are not showing that the acoustic centres are aligned, just that the voice coils are, not the same thing. Acoustic centre moves around depending on frequency.
dave
I know what you are saying but look at the diagram. It says Figure 1 - Acoustic Alignment (4430), not Voice Coils Alignment (4430).
mark
I've given it some thought and I think you're right.
The inverted peak of the tweeter is about -50us. This is 0.05ms.
According to the Delay measurements, there is a tolerance of +-0.02ms. End to end would be 0.04ms. So, it is very possible that the impulse is showing what the delay measurements are not.
0.05ms works out to 17mm. One way is to use a 18mm mdf step for the woofer. This would be a bit difficult because I can't align the woofer center which means everything will change.
Another way is to use a passive delay network for the tweeter. This way, I won't have to move the woofer and tweeter.
The easiest route is of course to use a digital delay. Find one that can adjust at 0.01ms. Better still, at 0.001ms.
What say you.
True. But JBL is one of the BIG BOYS. What are they trying to say by having that diagram.
I had a Dyson once it was bit loud but not as loud as the other vacuum I still have as back-up. The SPL db/freq on it is like 109db with 400Hz peak and slopes downwards each side. Too much it made me feel dizzy and almost blackout once.
I got a smaller vacuum Hoover spretiz while checking specs on it for 85db what the specs don't show is freq! As soon as I got it it checked out on the SPL meter and freq was a lot calmer without a huge peak frequencies.
Anyway on with "Time Alignment" with multi DSP DCX or whatever?
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