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Multi-Way Conventional loudspeakers with crossovers

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Old 21st December 2012, 12:43 PM   #371
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Quote:
Originally Posted by Silent Screamer View Post

There isnít a great deal of efficiency difference between the drivers. The dipole tweeter is around 93dB at the front and slightly less at the rear. The 12MU8731T00 are 87.2dB wired in parallel which should give me around 93dB, and the 18WU4741T00 are 87.2dB wired in series - parallel (not exactly sure what that give me).
Well - that's the data on the paper you are referring to?
What did you measure?

The attenuation via the front panel menu is done in the analogue domain AFTER the DAC, so no bit reduction in the digital domain = better.
If you attenuate in the software setup you will attenuate in the digital domain.
Conclusion - if there is a big difference between driver sensitivity AND gain of used power amplifier channels it is advisable to attenuate the drivers via the analogue path. I think you use a multi-channel amplifier at the moment and the gain of these channels will be the same whereas if you where using different power amplifier from different manufacturers you would also have to take this into account and this is simply by comparing the measurements of single drivers/power amplifier combination relative levels.

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Old 21st December 2012, 01:05 PM   #372
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Yes that is based on data sheets but currently I have no gain added to any of the drivers, and they all seem to produce a fairly even SPL, but as you say 5 out of the 7 channels are currently coming from the same amplifier. I will keep this in mind for down the track when I upgrade the 5 channel amp for something better.
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Old 21st December 2012, 05:21 PM   #373
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You could also (for the group of drivers under test) run a pink noise signal through each channel separately ... align the levels with Roberts analog stage, or your amps. I'd listen to some music program then just to be sure the tweeter isn't too low in level. (Might sound fine to you ... might want another 2-3db of gain)

Then run your tests.
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Old 21st December 2012, 10:43 PM   #374
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Originally Posted by Tordenguden View Post
Why did you buy in the US? Don't you have music-gear-shops down there? It's just a 1/4" jack to jack cable, at about Ĺ meter. Should be extremely common in the music business.
Could you post pictures of the soundcard with cables and the buttons. Then it will be easier to figure out, if we are doing the same thing
Because most Australian retailers have no concept of the word moderation. What costs $5 in the US cost $20 here, so I can buy from the US pay freight on small objects and still cost much less.

The other problem is range... Anything that isn't mainstream isn't kept and needs to be ordered in for an even more ridiculous price. The Y adaptor is not a mainstream item.
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Old 21st December 2012, 10:53 PM   #375
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Originally Posted by puppet View Post
You could also (for the group of drivers under test) run a pink noise signal through each channel separately ... align the levels with Roberts analog stage, or your amps. I'd listen to some music program then just to be sure the tweeter isn't too low in level. (Might sound fine to you ... might want another 2-3db of gain)

Then run your tests.
You have just given me an idea. At the moment I have only worked out how to create a xover that is ganged to the first channel. Which in turn provides no flexibility to the second speaker crossover i.e. Separate delays etc (I am hoping this is just me and not a software limitation). Using the individual attenuation in the DCN28 I could at least do a pseudo balance if the room dictates that one speaker must be closer.
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Old 21st December 2012, 11:05 PM   #376
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Quote:
Originally Posted by puppet View Post
You could also (for the group of drivers under test) run a pink noise signal through each channel separately ... align the levels with Roberts analog stage, or your amps. I'd listen to some music program then just to be sure the tweeter isn't too low in level. (Might sound fine to you ... might want another 2-3db of gain)

Then run your tests.
Just looking at the full range graphs in posts no's 356 & 360 and it looks like I might be able to drop out two of the 18WUs, as it is a few dB higher, as an alternative to attenuating the channel.
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Old 22nd December 2012, 02:21 AM   #377
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Been doing some more measurements this morning. An interesting observation when measuring each of the drivers in its “optimal” mic position (on axis ~6” away)… each driver is a lot flatter then when it is in a not so optimal position (measuring another driver).

Which has me thinking again while it is great for speaker manufactures to measure their driver in the ultimate light that makes them look fantastic. Unless all of the drivers are clumped in one spot to some degree you have to be listening to some of the drivers in a vertical off axis position.

Which makes me further think any correction should also be done when measured from the listening position. I won’t get it as flat as if I was measuring near field, but I don’t plan to listen to the speaker from 6” in front of the tweeter, I plan to sit down to listen to them.

Do I want to know what I really have in my seated position? or have a dead flat response to say it looks good? I listen with my ears not my eyes, so I am thinking what is right is from where I am sitting.
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Old 22nd December 2012, 02:45 AM   #378
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I'm a noob when it comes to this kinda of stuff, however I'm a believer in listening from the intended listening position. What good is a freq response curve that looks great from say 1m, when at 2-3m off axis the whole picture falls apart.

I do believe that near-field measurements are great for getting crossovers correct, measuring at the intended listening position and of course your ears should be the final say so.

I know for a fact that my setup isn't ideal, however it sounds great so far with very minimal "tuning" and I'd be hard pressed to make any more changes to it until I have much more time on my hands. Also - the wife approves

EDIT: The only downside as far as I can see about measuring at the listening position is discovering how "bad" a room can be to accurate frequency response...treatments and speaker position could be vital here more so than adjusting the audio source-to-speaker chain itself.

Last edited by siruis815; 22nd December 2012 at 02:54 AM.
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Old 22nd December 2012, 04:47 AM   #379
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Yes I tend to think the answer lays in there somewhere...

I can't swing a cat in here now so there is no room for accoustic improvements, but that is not to say it isn't on my list of things to do in the place I will be getting.

I am just trying to convince myself it is a good idea because most of the people I think know what is going on seems to measure closer to the speaker.

When I try to do individual speaker measurements, then corrections, the corrections sound like crap, and the base crossover sounds better.

I have had some improvements with the corrections but I think that was when I was closer to the speaker, so it looks like more trail and error is required.

I also can't wait to get my cables sorted out because I have no idea how much that is contributing to measurement corruption.
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Old 22nd December 2012, 05:44 AM   #380
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Yes, yes, yes Silent. The slight downward tilt into the highs at the listening position is good! You do not want flat at your position. It will be overly bright.

Still with the wider range on the mids?
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