need help with crossover design

[eitanwaks]

hi,
I know this question has been asked a lot however I cannot find the information using the search.

I'm building a two way speaker with the following drivers(files with specs are attached):
Tweeter - Morel Supreme 110
Woofer - Morel MW267

I have already built my cabinet (designed after the magico's).

I have tried using Xover Pro to design a crossover. I have no experience design crossovers and I'm not sure if the results are good. I have used theoretical results given from the company and have not actually measured my speakers.

The crossovers are also provided here in attachment.

Are they any good?
How should I proceed from here?

Thank you very much,
Eitan Waks

[Jidis]

Eitan,

I'm struggling with my own right now as well.

Not sure if you're willing to get wrapped up in much multitrack audio software mess right now (or if you aren't already), but I'm going a weird route on mine which seems promising:

I've got my hi/low drivers temporarily bi-amped with direct feeds to each from the amp's left and right channels. I keep a mono source track in an audio program which is routed out to two separate mono output busses (one outputs to the left channel, one to the right). Each of those output busses contains a plug-in EQ set for either a high or low pass filter. I can either place an audio file on the source track, or insert a virtual tone generator on it and spit out sines or pink noise, and the signal gets split and filtered to the two drivers. While it's playing, I can sweep around on the EQs to audition different crossover frequencies, as well as changing the slopes for different filter orders. There are also usually a few places where you can easily flip the phase to see how that does, but I haven't generally liked it. Note- Much of this stuff depends on whose audio program you're running and which EQ plug-ins you've chosen, but it's no problem rounding up capable free stuff in both areas today.

Just something to think about I guess.

Take Care,

George

PS- Should you try that, obviously keep an extra close watch on your levels and the content you're feeding the drivers. If you were to screw up and bypass an EQ, sweep too low, or pan something wrong, you could blast your tweeter with unfiltered lows.

[Iain McNeill]

That's a clever way to audition XO's Jidis! Nicely done. You could even add a delay plug-in to correct time alignment as well.

However, you are both shooting in the dark without acoustic measurements of the drivers. While the generic responses of the drivers from the manufacturer are an OK start point they are for infinite baffle and will differ from the performance in your cabinets.

You don't need a calibrated mic for audio measurements, a cheap 6mm omni electret is plenty good. In fact that's what a lot of the cheaper measurement mics are.

Search the forum for all the good testing freeware. There's tons.

[Jidis]

Originally Posted by Iain McNeill

You could even add a delay plug-in to correct time alignment as well.

Yeah, I was actually running a plug called "PhaseBug" for a bit on one channel, which lets you offset +/- 180 degrees, but it scared me. I usually liked it best at 0 or bypassed and I was afraid that if I heard something I liked other than that, I'd have a heck of a time trying to recreate it with passive parts in real life.

I'm hoping that setup was as close as I could get to real world results. The drivers are already mounted in a prototype cabinet which is the exact internal dimensions of the final ones. If I can ever get my frequencies chosen, I'll be hand picking the caps and winding the coils with an LCR meter, and I'll be sure to get the exact impedance specs for each driver in the actual crossover range before doing any calculations.

Right now, there's an Apex measurement mic mounted in front of the test speaker, about 2 inches from the baffle face, and about midway between the drivers. I tried watching some pink noise on a software RTA and it gave me a headache. The initial response seemed surpringly flat, but smoothing it out with the software EQs ended up sounding horrible when I played music through those same settings. I started thinking I may be best off to just use a wide range of (musical) source material for the tweaks and not look too closely at the mic's impression of it. I'm going to read up some more on setting up for the measurement tests though. I suspect my methods there were probably flawed in ten different ways.

Take Care

[eitanwaks]

Jidis,
your method of testing for proper crossover seems very interesting. Luckily for me I just finished getting my bachelors degree in mechanical engineering and I'm taking a break from work and studying so I have some time to fiddle around with these things.

Could you please elaborate on your method. I would love to know what programs you are using (I have access to all of the Adobe programs). I would also love to know what microphones are recommended (I have none at the time).

All in all, I think I'll try your method before committing to a crossover. I would love to get as many details and references as possible.

I actually thought of something. I could write a program or script that could actually go through all of the frequencies (20-20K FOR example) and at each frequency goes through several different slopes (6/12/18/24 dB). The output of the program would be the most linear combination. Would this be something that would help in building a crossover?

Thanks for the help,
Eitan Waks

[Jidis]

Hey again Eitan,

In a bit of a rush tonight, but I'll try to describe it. I'm running Nuendo (by Steinberg, similar to Cubase), but I've also got a project setup in Reaper which does the same thing. Also, the two EQ plugs I've been using are part of Universal Audio's Powered Plug-Ins system, which requires hardware, but there are about a million parametric EQ plugs with similar functions and layouts. There's also a free VST plug out there called "Rubber Filter" which does nothing but filters (which is all I'm using my EQs for here). Audition or whatever you end up running probably won't be exactly the same to get this result, but I'm sure there's a way.

In Nuendo, you can create multiple output busses (either mono or stereo) which your audio tracks can be routed to. These in turn, need to be assigned to physical hardware outputs. In my case, they are two mono busses named Woofer and Tweeter, routed to the left out and the right out. Nuendo allows for plug-in effects on these bus channels, so there's a Cambridge EQ on each of mine doing the filters. Then you just need some source channel to feed the two output busses. I have one mono track in the project doing that. I can place audio on it, but it's also got a test tone plug inserted which I can switch on to output tones and noise. That's coincidentally a freebie called MDA TestTone. To get the source channel to the two outputs, I'm actually using the channel's "sends". Nuendo gives you eight of those per channel, and they can be set to "pre-fader", so I can keep the volume for the source track turned down and keep it from double routing to anywhere else in the mixer.

That's about all it is, and again, it would probably be different instructions for another app. Again, just keep the volume extra low at first and test by muting or turning down one of the outputs to make sure you're getting the correct filtered signal to each driver and nothing else.

There's a whole slew of ways you can achieve that same thing with the EQ plugs and outputs too. My Reaper project isn't configured the same as my Nuendo one, but they both work. You can even just use two mono audio tracks, with the same exact file and an EQ insert on each, then pan one hard left and one hard right to a regular stereo output with no plugs on it. I chose the single source track thing as it was easier to drag files onto it and run the tone plug.

I'll attach a picture. The mono in channel is what I was using for the measurement mic, but as I mentioned, I got more feedback from just listening to material. If you can make out the text, those plug inserts that say "Voxengo SPAN" are a free analyzer plug I was using to compare the source signal to what the mic was picking up from the speaker.

Hope that helps,

George

[eitanwaks]

hi,
after researching on the Internet all the programs that you mentioned I noticed that Nuendo is actually the studio audio program. That got me thinking. When I was in high school I had a friend who is a musician. He ended up opening a music studio several years ago. We haven't been in contact since high school. I ended up giving him a call this morning. I asked him what software he uses and sure enough he uses Nuendo and offered to let me use it well his studio has downtime. So now access to that program .

I also found the VST rubber filter you mentioned and downloaded it. Like you said, for my purposes (and I suppose yours as well) it is more than enough. The Cambridge EQ is an overkill in my opinion for my needs (and so is Nuendo when you think about it, but as long as I have access ). By the way, the new version of Nuendo [4] has VST filtering plug-ins bundled with it and they might be good enough. I have not tried it yet.

I also got the tone plug-in. so now I'm ready to go, except for a few things.

I've been trying for a couple of hours now to find (good) information about how to test/measure loudspeakers both on the net and in this forum. I could not find any comprehensive and complete tutorial/description. Can anyone please point me in the right direction?

in addition, even though my friend who owns the studio has the program, he's not in charge of mixing. He runs the place. I don't feel comfortable asking the technician there for instructions on how to use the program. Can anyone please give me a small tutorial (or point me in the right direction) on just the features I need. [The program runs on both his desktop connected to all of the audio equipment, and on a separate laptop. I think I will use a laptop because I have no experience with analog equipment connected to the desktop and I don't want to mess anything up] click submit reply

one more thing, I kind of messed up with the cabinet. I didn't leave any flat spaces in the back where I can easily attach connectors for cables. Does anyone have any suggestions. I'm going to upload pictures of the cabinet as soon as my digital camera starts working again (hopefully tomorrow).

Regards,
Eitan Waks

[Jidis]

Hey Eitan,

Can you get by with a pair of individual screw terminals or something? Seems like you'd only need about a half inch or so of round space for each one and they might not even need to be side by side. Might be easier to fit than a big plastic panel or cup insert.

Re:Nuendo- I've run studios for about the past twenty years, which is the only reason I need stuff like that and the UAD plugs. If you get serious enough about doing any multitrack and you like that app, its brother program (Cubase) is based on much of the same code and looks almost identical. Nuendo just has some post production features added. There are inexpensive entry level versions on Cubase. I think some even come bundled with soundcards and stuff.

Here's a brief rundown on setting up this stuff in Cubase/Nuendo. Note- My instructions would be for versions 2 or 3 (I haven't upgraded), but much of it may still be in 4 or 5. I also won't get into the initial sound device setup. I'm guessing the defaults will all work there, but if you need it, that stuff should be in the Devices Menu under Device Setup> VST Audio Bay.

- File Menu> New Project (just select "Empty" if it asks for a type, then point it to a folder to save in)

- Project Menu> Project Setup (set your sample rate/bit depth)

- Devices Menu> VST Connections> "Output" tab (right click whatever stereo output is there and remove it, then click add bus and make two new mono busses)

You can rename them to Woofer & Tweeter in that left column there, and you need to make sure they are assigned to the correct physical outputs over in the Device Port column on the right (you can click/change them there). Close VST Connections.

- Project Menu> Add Track (Audio/Mono)

- Hit F3 to open the mixer

- Hit the "e" edit button on your new "Audio 01" channel to open the channel settings window. Bring the fader all the way down. Go to the bank of sends on the far right of that window and click in the black space of one. Set it to Woofer. Set the next one to Tweeter. Click the first two buttons above each of those. One enables the send and the second sets it to pre-fader (since you have the volume all the way down on that channel). Below the names is actually a fader bar for the send level. You can drag that across to zero, or ctrl-click it and it will go there (if it stays on minimum, nothing will go to those outputs).

- Click the same "e" button in the mixer for one of your two output busses. The bank of eight black bars near the left in the channel settings windows are your plug-in insert slots. Stick a RubberFilter or whatever you want on one of the slots on each of those output busses. Set them for high or low pass,etc.

- Go back to the main project window and do File Menu> Import (Audio File) and point it to whatever audio you want to listen to (you can probably leave most boxes unchecked). It should land on that single track that you've got.

That should be it. When you play it (Space), it should show up at those two outputs and pass through the respective filters.

Hope that's enough to get going! And again, double check everything at low volume to be safe.

George

PS- That TestTone plug comes from here. You can get an analyzer from here.