3 way speaker with 1 order filters

Hyldal

Member
2006-09-06 1:01 pm
I would like to try and make a 3 way speaker with 1 order cross overs, in the 500-800 hz range and 3500-4000Hz range. And I will timealigne each driver.

The midrange driver will have a hard time to cover this range, I would like to hear witch ones you would recommend me to check out?
I am concerned with the dispersion of the midrange I cuess I will make It difficult to integrate with the tweeter, but B&W is doing it this way in all there high end speakers today, so i guess it can be done.

Other comments hints on such a system is welcome
 
I'm actually building a three-way speaker with passive first order filters at the moment, although with rather different crossover points. One thing you need to remember (as well as the obvious one about the drivers' need to work adequately over a larger frequency range than the nominal crossover points) is that if you are using a passive crossover (as I guess you are), that you will need to add a series C-R network across the woofer to correct for its rise in impedance with increasing frequency. You will also need to add the same for the midrange unit and also add a series R-L-C across it to compensate for the rise in impedance at its resonant frequency. If the tweeter is ferrofluid-damped you might get away with not needing to compensate this, as the ferrofluid damps the resonance nicely.
For a simple first-order crossover to work well (based on measurements I've done on two-way units), you need to make the drive units look as resistive as possible over the full frequency range so that the crossover is working into the right load.

You may well need to tweak the crossover after you've built the speakers to correct for any response anomalies. I hope you've got a measuring mic and suitable test software (and a quiet day to measure the speaker outdoors!)

When you get it to work well though, I find that using first-order crossovers give the speakers rock-solid stereo imaging.

I'm lucky in that I have access to a proper anechoic chamber and B&K measuring microphone, but it's still a lot of work.
 

Hyldal

Member
2006-09-06 1:01 pm
Thanks for your hints with the impedance control. I was also planing on that. I am more worried about the dispersion of the tweeter and midrange in the crossover region that are very wide in a 1 order system.

Where do you put you cross over frequences?
What midrange driver are you using? The only driver I know I will use is the relatively new D30 Scan Speak dome.
 
Hyldal said:
I would like to try and make a 3 way speaker with 1 order cross overs, in the 500-800 hz range and 3500-4000Hz range. And I will timealigne each driver.

The midrange driver will have a hard time to cover this range, I would like to hear witch ones you would recommend me to check out?
I am concerned with the dispersion of the midrange I cuess I will make It difficult to integrate with the tweeter, but B&W is doing it this way in all there high end speakers today, so i guess it can be done.

Other comments hints on such a system is welcome


I think you are going to have issues crossing around 500-800. This is slap bang in the middle of the vocal and most music fundamental range. Far better to aim at crossing around 200-250 and 2000-2500.
The other thing you MUST have for low order x-os is drivers with a very flat response to start with. There are several 5" drivers that you could use for your mids, eg Peerless Nomex 5", GR M130-16, Vifa PL11WH. Even your bass driver should avoid large peaks in the response, which makes choices a bit harder. Maybe the new Peerless SLS drivers, but I haven't used them yet.

I also suggest using an MTM + W rather than a straight TMW with low order slopes because it helps the midrange drivers cope much more easily and gives a balanced sound pattern through the all important mids..

Most of the speakers I now build are of this configuration, but with the mids used in an open back U-frame. works beautifully !!!

You will notice with the Blackwood x-o, below, that it is a series network, not the normal parallel, and that no LCRs etc were required.
My latest , called "The Rocket" does use a zoble on the mids, again, nothing required on the bass.

http://members.optusnet.com.au/~gradds55/ARGOS/blackwood.html
http://undefinition.googlepages.com/diy-aethers
 
Quoting Zaph on his ZD5 project -- http://www.zaphaudio.com/ZD5.html

I wonder why he says the next step is no crossover at all in a full range driver? He seems to discount 1st order.

I'll admit that I played with Scanspeak drivers and couldn't get a 1st order to sound right on most types of rock. I was playing at under 85db, too. On some musical material it did sound lush, though.

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Accurate 2nd order slopes are hard to pull off, and only very wide bandwidth drivers with smooth response and low distortion need apply. Make no mistake that shallow slope crossovers sound better than steep slope crossovers. But doing shallow slopes right amounts to much, much more than just throwing a cap and coil on the tweeter and woofer. My Waveguide TMM design was more of a hardware solution addressing some typical LR2 design issues. This Scan Speak / Vifa system is more of an electrical solution.

In the end, an LR2 design has 180 degrees of phase wrap through the crossover while an LR4 has 360 degrees. The lower phase wrap directly equates to an improved midrange coherency. Honestly, most drivers and system designs require LR4 or greater slopes just to work properly. But when everything comes together for a LR2 system, it's the sweet spot in speaker design. Why is it the sweet spot? Because the next step is no crossover at all in a full range driver, which is a step backwards, introducing a whole different set of problems that detract from good sound.
 

Hyldal

Member
2006-09-06 1:01 pm
Andy, very nice systems you have build there. I think you are right about lowering the crossover frequences, and use a bigger midrange driver. That will probably take care of the problem with different despersion from the midrange and tweeter in the crossover area. but put more stress on the tweeter.
200-250 hz for the midrange, I guess that will take a midwoofer and not only a midrange driver.

Let me hear comments from you all, I understand the scepsis of a 1 order system, I am/was also, But now I will try it out.

I am thinking to use some of the baffel step as a part of the midrange highpass filter. And there the crossover frequence will be for the woofer and midrange.
 
Daveis said:
What dome tweeter can handle a 1st order filter at any crossover frequency under 10khz?



In my current 2-way speakers I'm using an Audax TWO34 (Fs of 800Hz with a 34mm dome). This is quite happy crossing over first-order at 3kHz, provided that you add the L-C-R network to compensate for the impedance rise at Fs.

I'm about to try using some old Audax HD13D37 units in a home made TL speaker (Fs of 700Hz with a 37mm dome), but only crossing over from the bass/midrange at 2kHz. As this unit is only good to 12 or 13kHz, I've got a couple of Audax TM020G7 units to act as 'super-tweeters'. I'll cross over using first-order networks between the two at 6kHz.

I don't listen at high levels so this helps the tweeters to have an easier life.

I'm lucky in that I've got access to a proper anechoic chamber and a B&K4133 measuring mic, so I can properly tweak the crossovers. I wouldn't trust mine or anyone elses ears to set things up.
 
Hyldal said:
Andy, very nice systems you have build there. I think you are right about lowering the crossover frequences, and use a bigger midrange driver. That will probably take care of the problem with different despersion from the midrange and tweeter in the crossover area. but put more stress on the tweeter.
200-250 hz for the midrange, I guess that will take a midwoofer and not only a midrange driver.

Let me hear comments from you all, I understand the scepsis of a 1 order system, I am/was also, But now I will try it out.

I am thinking to use some of the baffel step as a part of the midrange highpass filter. And there the crossover frequence will be for the woofer and midrange.

I strongly suggest that if you are using low order slopes for a 3-way you read through the series x-o stuff found on my web site.
http://members.optusnet.com.au/~gradds55/SeriesXO/series_cross-overs8.htm

if you particularly look at the sim done by Wil and Tony Gee under the "1st order 3-way" then"Linked series" page, that no LRC's is required on the tweeter or mid or bass. sometimes a zobel is required on the mid.
In both case look at the impedance curve produced !!!! :yummy:

I have now built 5 or 6 of this style of loudspeaker, all have worked well for listening !!

As for stress on the tweeter, use a Seas or similar grunty tweeter, extra padding will generally mean that there is no problem what-so-ever. I have used 1st order x-os on about 40-50 speakers, and I and others have been quite punishing with spl on many occasions :D and have never blown a tweeter.

oh, and sorry for the grumpiness earlier, been a long day :rolleyes:
 

Hyldal

Member
2006-09-06 1:01 pm
I have Clio Lite meassuring system, but no anechoic chamber unfortunately.

I am a bit supprised that you kan make you 1 order systems work properly without having the tweeter put behind the midrange. I guess It is not needed the midrange is put behind the bas driver(s).
 
Hyldal said:

I am a bit supprised that you kan make your 1 order systems work properly without having the tweeter put behind the midrange.

Probably because I don't listen with a microphone in an anechoic chamber !! :D

There are things you can measure that you don't hear......

And there are things we can hear that measurments don't tell us....

how's that for fence sitting (barb wire fence) !! :bigeyes:
 

Hyldal

Member
2006-09-06 1:01 pm
I agree, the most importat is what the ears can hear. Today to many meassure to much and listen to little!! No matter if it is amps, speakers or signal sources we talk about.

I think I will go for a 5" MG14 vifa driver for the midrange,, I like fiberglass cones, and a D30 scanspeak dome for the tweeter, also because I have these drivers "in stock"
 
Hyldal said:
I am thinking to use some of the baffel step as a part of the midrange highpass filter. And there the crossover frequence will be for the woofer and midrange.

Run your woofer up to around baffle step frequency and alter the mid and tweeter SPL to suit. Takes care of BSC in an easy manner.

I have to agree with Andy that good quality tweeters are tough and have never fried one using 1st order crossovers. Even accidently crossed one over just above it's Fs and besides sounding a tad harsh, it survived with no damage.... a TC20TD.

I can vouch for Andy's 1st order 3-ways as I am lucky enough to get to hear them.... doing a road trip to Andy's on Friday to check out another.