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Multi-Way Conventional loudspeakers with crossovers

Quick question for the experts
Quick question for the experts
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Old 27th February 2019, 08:13 PM   #1
giosblue is offline giosblue
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Default Quick question for the experts

I know lots of things effect the bass output of mid woofer, room placement, cabinet size.etc But. does the crossover effect it? In other words do you get the full output and tailor the tweeter crossover to match?


Ron
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Old 27th February 2019, 08:27 PM   #2
bwaslo is offline bwaslo  United States
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Quick question for the experts
The crossover can affect the woofer, usually from the inherent series resistance of and inductors in series with the woofer. Usually heavy gauge or iron cored inductors are used in those positions to minimize the resistance. Other than that, in most cases the woofers are used at full level.

That's because of a couple reasons, but mostly because usually woofers are the least sensitive components in a set, so the tweeters and/or mids are attenuated down to the woofer levels.
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Old 28th February 2019, 06:16 AM   #3
giosblue is offline giosblue
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I thought so. This is the script so far. I have a pair of Acoustic Energy Radiance Ones. About 12 months ago I upgrade the tweeter to Scanspeak 3004/66000. The was in big improvement and I was very happy with the results, so I decided to upgrade the mid bass unit and this is were it's all gone wrong. I bought a couple 15/w8530koo driver in fitted them into my existing cabinets using the existing x/overs. This didn't work well, is was lacking bass and lower midrange, so I returned them because I couldn't get a x/over. Anyway, Because the Scanspeak mid woofers are so highly rated I bought two more, but with x/over. I fitted them thinking this would give me really nice sounding bookshelf speaker.
However, it's not worked out, they are still sadly lacking bass and Lower mid range. With original Acoustic Energy mid bass drivers the bass is fine. Any thoughts ?

Ron
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Old 28th February 2019, 06:28 AM   #4
AllenB is offline AllenB  Australia
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You want to use resistors to make the treble more quiet. You say you bought crossovers, but you still need to add resistors.
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Old 28th February 2019, 07:30 AM   #5
giosblue is offline giosblue
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The crossovers were supplied with the 15w mid bass drivers. They were specific to the 15w and the 3004/6600 tweeters. Just for the sake of clarity, I had no problem with the bass using the Acoustic Energy pressed alloy drivers. I'm going to have play around with the positioning and see how it goes. The only other thing I can think of is the size of the box. Having said that, there are quite a few kits using a box about the same size as mine.

Last edited by giosblue; 28th February 2019 at 07:42 AM.
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Old 28th February 2019, 01:47 PM   #6
Galu is offline Galu  Scotland
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Surely the box which was designed with the original Acoustic Energy mid/bass drivers in mind can't be expected to work with the entirely different Scanspeak drivers?

Or am I missing something?
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Old 28th February 2019, 02:41 PM   #7
David Morison is offline David Morison  Scotland
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Galu - OP's previous thread may be informative.

OP: A couple of things may be contributing:
1: have the new drivers been run in at all yet? Many people find that drivers do not perform at their best when fresh out of the box, but need some time running to settle in to their proper performance.
2: WRT the Scan's not working with the original crossover, it may be that the AE drivers needed less Baffle Step Compensation than the Scan's (perhaps due to an inherently falling upper mid response). If that were the case the minimal (or potentially absent) BSC in the original crossover would have left the Scan's sounding very light in the bass & low-mids in comparison.

I confess, I'm not enough of an expert to say wither of these factors is definitely at play, but they're both possibilities.
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Old 28th February 2019, 05:58 PM   #8
Galu is offline Galu  Scotland
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David - Thanks, very informative!

Ron's final post in his previous thread, suggests that he may have wired his drivers out of phase, thus explaining the lack of bass.

Quote:
"The first thing I noticed was that only one speaker was working, so I walked closer and listened to both, they were working fine. That's strange so I sat back down and only the left channel was working. However when I moved my head to the right, the right side was working, but I lost the left. It turns out, for some reason, unless you were dead centre, you couldn't hear both channels. Just by moving your heed you could switch from on side to the other. Honestly you would have to experience it to believe it."
Ron - Try reversing the connections to ONE of the bass/mid drivers.
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Old 28th February 2019, 06:55 PM   #9
giosblue is offline giosblue
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Gala, this is a different setup now. I couldn't get a x?over for that setup so I bought two 15w/8530 from Wilmslow and they supplied the x/overs Ok. a couple of things after further investigation.
Fist off, the speakers are in phase. However when playing a 100hz test tone it didn't sound right, both the tweeters and the bass units were not sealing properly. I could feel the draft around the edges. This is because the Acoustic Energy cabinets are made of compressed cardboard and when you screw the screws in in it leaves a raised l lump around each screw. So I need to fix.that. The other thing was the wadding is blocking the vent tube, so I've moved that. I did expect some compromise with the cabinet, but I thought it would only be minor. Anyway, I'll fix these and see how it goes.
Thanks for all you input, personally I think the x/over needs to tame the tweeter a bit to bring things more into balance?


Ron
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Old 1st March 2019, 03:49 PM   #10
Galu is offline Galu  Scotland
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Quote:
Originally Posted by giosblue View Post
I think the x/over needs to tame the tweeter a bit to bring things more into balance?
Hi Ron! Perhaps the following may help:

To reduce the 4 ohm tweeter output by 4dB you can wire a 6.8 ohm resistor (R2) in parallel with the tweeter terminals then place a 1.5 ohm resistor (R1) in series with the parallel combination as shown in the attached L pad circuit diagram.

Both resistors should be at least 10W ceramic wire-wound resistors like the ones available here: Ceramic Resistors
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File Type: gif L pad circuit.gif (1.4 KB, 325 views)
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