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Old 28th October 2012, 03:36 PM   #11
system7 is offline system7  United Kingdom
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I think you have to state at the outset whether this is a bookshelf, or a standmounter away from the wall. It makes a big difference to your options.

A bookshelf can get away with a small bass coil, maybe 0.6mH here. You then need to line up the tweeter to a -6dB point around 3kHz with this woofer. Traditionally you'd then use a second order (around 4uF/0.4mH) on the tweeter. This is like the old KEF Coda with the B110 bass unit.

The standmounter works pretty much as SEAS advertise in that "Exotic" 2.1 kHz crossover. Phase and levels are a problem with this sort of guess work. First order tweeter could be tricky, but see what you can do.

The W130S I used here is nowhere near as efficient as the Morel, but it's interesting to sim it for a closed box standmounter anyway. Phase wasn't too bad.
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File Type: jpg Seas_crossover_Sim.JPG (23.7 KB, 102 views)
File Type: jpg Seas_Crossover_Sim_FR.JPG (60.0 KB, 100 views)
File Type: jpg SEAS_Exotic_Crossover.JPG (34.0 KB, 101 views)
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Old 28th October 2012, 03:48 PM   #12
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Stand mount...front ported...sorry!!

You know Steve...thank you so much for your time on this...I really do appreciate all your help and suggestions!!

K...looks like that's a good as any place to start...coil on the driver and a simple network on the tweeter as you suggested!!

L-pad?? Would that help any??
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Old 28th October 2012, 04:06 PM   #13
system7 is offline system7  United Kingdom
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I'm interested in Morel drivers, as it goes. People here slag them off for reasons I really don't understand. This one looks fun.

Let's reiterate what the Morel HU 621 frequency response is below. Your bass coil will tilt that down essentially and do the bafflestep correction with any luck. It's gonna be between 1mH and 2mH IMO, but it's trial and error without accurate modelling.

You will then be left with a sharpish rolloff at about -6dB @ 3kHz as mentioned. Your second order filter needs to come in at this point. You can model that bit in Boxsim to a large extent. With bafflestep correction, inevitably the tweeter needs attenuating so some sort of padding is essential. Not necessarily an L-pad. Sometimes a resistor in front of the treble filter works well too.

Try a fist order treble by all means, but I think it will be messy. At which point, I must duck out for now. Quite a tiring day at the forums, and the NFL football kicks off soon...
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Old 28th October 2012, 04:35 PM   #14
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See...I don't get that either...I have not heard a bad Morel driver...they are great!!

K...gonna order some parts...a couple of coils...a set of L-pad's for giggles...caps I can get at work...will play around as soon as I can get some stuff in...will keep you posted!!

Go Bears...Go Pats!!! My SB picks :P
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Old 28th October 2012, 08:41 PM   #15
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Oh ya Bears...lucky buggers...horseshoes!!!!
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Old 29th October 2012, 12:23 AM   #16
system7 is offline system7  United Kingdom
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Very lucky indeed. NYG had me worried for a moment too.

I do remember one fairly successful first-order crossover I modelled.
Sreten & Speakerman go at series XOs

Phase was very good and it looks like a standmounter. The resistor can go after the capacitor too if using L-pad. Wouldn't push the volume control too hard though. Hope it helps.
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Last edited by system7; 29th October 2012 at 12:26 AM.
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Old 29th October 2012, 01:48 PM   #17
system7 is offline system7  United Kingdom
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sideways, reference your query on good test values to try on the crossover, I include a sim. Your Morel is rolling off around 3kHz, so the sim isn't showing what is going to happen exactly and it will be better than this I reckon. Surprisingly the tweeter is wired out of phase here, but who knows how it'll turn out with the Morel.

4.7uF for sure. As the adjustable input resistor on the treble filter gets smaller, the treble coil gets bigger to approach 0.4mH, but I think 0.2mH is OK down to about 3.3 ohm input resistor so lots of leeway. If I had to guess the (red) input resistor, I'd go for 4.7 ohms initially given the woofer is efficient. It really doesn't work so nicely with an L-pad.

The bass coil is another moveable feast. Hard to guess, but 1.5mH will be less bassy than 2mH and might be realistic since no-one has speakers in the middle of the room. There's always a little wall reinforcement.
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File Type: jpg Morel_Test_Crossover.JPG (22.6 KB, 79 views)
File Type: jpg Morel_Test_Circuit.JPG (64.1 KB, 29 views)
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Old 29th October 2012, 01:59 PM   #18
sreten is online now sreten  United Kingdom
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Hi, Morel drivers aren't bad, just expensive for what they are, rgds, sreten.

Having said that, the MW166 gets a fair bashing here : Zaph|Audio
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Old 29th October 2012, 05:45 PM   #19
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Hey Steve

You know if I can wrap my head around some of these programs...Boxism...PCD...I might have been ok but this old brain of mine can't seem to get them to do what I want them to do LOL!!

Anyhoo...parts list...hopefully I get this right...

Woofer: 1.5mH coil

Tweeter: 4.7uF cap, 4.7 ohm resister inline with the cap, .2mH coil across the tweeter

What's the 8.2ohm resister across the tweeter for??

The 4.7 ohm resister inline with the tweeter can be changed in value to attenuate the tweeter correct??

Tweeter is out of phase because it is a 2nd order xover correct??

I hope I'm getting this all LOL!!



BTW...I've heard the 166 and I think Zaph is unfair...specs don't always tell you the whole story!!
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Old 29th October 2012, 06:07 PM   #20
xjr100 is offline xjr100  Europe
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Quote:
Originally Posted by sideways View Post
... some of these programs...Boxism...PCD...
If you do not put measuremnts of your drives in some CAD which can help to design crossover you will get some result, but definetly it will not be correct one, just some aproximations, and your part list can be absolutely wrong.

Correct way of crossover design is to measure you drivers in-cabinet (both - phase and freq.ressponse), add there impedance measurements for each driver and then play with schematics in CAD to get flat response from the system.

Boxsim is good for Visaton drivers and constructions, as driver parameters are there, but it is also approximation and real life responce is different from the model.
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