First Post - Watt Puppy style project - crossover question

**cjd** · 02 February 2012, 11:18 Thursday

what's your location ? even actuve the trick is going to be getting good measurements .

**funkdrmr** · 02 February 2012, 11:19 Thursday

I'm in Austin, TX.

**funkdrmr** · 06 February 2012, 01:30 Monday

Understanding the key is to getting good measurements....any info on obtaining those? Which software and or microphones are recommended?

I've gone through the Passive Crossover FAQ & checked out a few of the programs. Did some impedence measurements on my desk here & played with those a bit, but I don't think I'm getting all the info I need.

It seems likely that I need to have the cabinets finished with the w/m/t's mounted in order to take the proper measurements?

I've called Rhythmik Audio, and other local hi-fi shops to see if they could handle the measuring / crossover design, but they all say they don't handle that sort of thing.

I understand what a crossover "does"....I'm a musician and a halfway decent recording engineer with a basic electronics background. I just don't have a solid direction on how to go about designing my own from scratch.

**Hank** · 06 February 2012, 14:39 Monday

Hi funkdrmr, I'm in Austin and a guy from our old home theater group is a EE and at one time had a top-shelf test/measurement setup. He and one of the other guys actually started a speaker company as a sideline but it became too much of a time hog and they shut it down. They had some good designs, though. I'll send an email to one of them and ask if they still have the hardware and software. BTW, I've got a Beringer mic if you need it.

**funkdrmr** · 06 February 2012, 16:06 Monday

Thanks, Hank! Please let me know if they're interested & how to get something set up!

I was figuring the Behringer may be one way to go. I don't own one, but figured Rock 'n' Roll Rentals would likely have one to rent out....or hell, could probably pick it up at Guitar Center if anything.

I'm kind of dumbfounded at how I haven't been able to grasp the concepts yet. I understand EQ, I understand the slopes, impedance, sensitivity, etc...I just have ZERO idea where to start in getting the measurements, and how those measurements translate into a crossover network that I can then purchase the parts for.

**Bear** · 06 February 2012, 16:54 Monday

Originally posted by funkdrmr

Thanks, Hank! Please let me know if they're interested & how to get something set up!

I was figuring the Behringer may be one way to go. I don't own one, but figured Rock 'n' Roll Rentals would likely have one to rent out....or hell, could probably pick it up at Guitar Center if anything.

Get a calibrated microphone if funds allow it. Standard rental mics might be good or they might be ... rentals. The Dayton Omnimic is also a good option for a bit more than a Behringer, but less than a Behringer + Preamp + Software.

I'm kind of dumbfounded at how I haven't been able to grasp the concepts yet. I understand EQ, I understand the slopes, impedance, sensitivity, etc...I just have ZERO idea where to start in getting the measurements, and how those measurements translate into a crossover network that I can then purchase the parts for.

Start with the basics: capacitance, inductance and resistance. Wikipedia has the basic equations and you can start plugging some numbers into a calculator or a spreadsheet (PCD, passive crossover designer, is an Excel-based crossover simulator that's free -- a good place to start once you have a basic feel for what the components are doing).

After you get a basic feel for R, L & C individually, then start looking at how they interact. This is where your knowledge of slopes and EQ starts to intersect with the circuitry that makes it happen in the analog domain. Vance Dickason's Cookbook is a good book to pick up at a nominal investment, but my main criticism is that it has absolutely no depth. It's truly a cookbook in a knowledge domain where that format of pedagogy doesn't work. But it's a start. You will come out of it with more refined questions. Siegfried Linkwitz has a great deal of information on his site, even if it isn't all kept completely up-to-date and the links all work (some of his best material seems to require Google rather than active navigation). Also read closely some of the more well-documented designs here. There is a lot of good discussion here that can help enlighten the compromises people are making when trying to create designs. In other words, lots of reading ahead!

**Hank** · 07 February 2012, 14:28 Tuesday

funkdrmr, if you get serious about a mic, I spotted this new one at Parts Express:

Page not found

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=392-212&FTR=calibrated%20mic#SimilarProducts

I noticed that it can handle extremely long cable runs, so if you're using a desktop rather than a notebook and want to take measurments in your back yard, the long cable run would be no problem.
I'd advise you to consider paying someone to do the testing, or paying someone to teach you how, and borrow their equipment before you invest any money in software, some of which is expensive, and hardware. If you get bit by THE BUG after your first DIY speakers, then you could make the investment.
I have not mentioned your situation to my bud at Dell (one of the guys I mentioned in my first reply to your post), but will now send him an email and ask if his former partner still has all the measurement software, audio card, preamp and mic. I'll also propose my two alternates above and he can check to see if there is interest. If the EE is too busy, maybe he'll loan/rent you the equipment - who knows?
BTW, you don't have to complete cabinets in order to test your drivers/crossover, but you should make baffles the size of your envisioned finished speaker baffles and test your first pass "system" using those baffles.

**funkdrmr** · 07 February 2012, 14:55 Tuesday

Very cool, thanks again.

I'm seriously okay with paying someone to do the testing. As far as "THE BUG" goes....I'm already looking to build a set of Statements, and some other smaller projects for my kids, so I think it's too late to turn back on it now. WAY too many cool projects to have fun with.

For your friend at Dell....let him know I work at an MSP in town & just got 2 Dell servers for one of my customers. Maybe that'll help sway him? hehe :-)

In all seriousness, thanks for any assistance that you can send my way. It really is appreciated.

**Undefinition** · 07 February 2012, 21:13 Tuesday

Originally posted by funkdrmr

I'm kind of dumbfounded at how I haven't been able to grasp the concepts yet. I understand EQ, I understand the slopes, impedance, sensitivity, etc...I just have ZERO idea where to start in getting the measurements, and how those measurements translate into a crossover network that I can then purchase the parts for.

Speaker design is deceptively hard. I spent like 10 years of just stumbling in the dark, trying to wrap my mind around it and couldn't. Then I found the DIY community on the internet, and built a "proven" design. From there, I was hooked. Still, I'd say it took me 4 years from that point until I really had a firm grasp on what I was doing, and how to get things to work the way I wanted.

The best book I know of on the subject is "Speakerbuilding 201" by Ray Alden. it's not perfect, but it's a lot more practical and understandable than any other speakerbuilding books I've read. Still, it took several reads over some parts over a period of time for certain concepts to start to make sense.

Also, the DIY community that exists on the internet now is great. I personally recommend this smart cookies on this site, and also the chums over at the Parts Express Tech Talk board.

**Hank** · 08 February 2012, 08:47 Wednesday

My Dell bud says his system has been disassembled for quite some time and he is snowed under at work, but appreciates your server purchase. He will email the other guy to see if his system is still intact and if he has time. I wouldn't count on it, however. Here's the advice:
· Get copies of the Loudspeaker Design Cookbook and Testing Loudspeakers
· Download Room Eq Wizard (free measurement software meant for acoustical analysis, but it can also do frequency response curves for speakers). His Woofer Tester can do the impedance measurements for now.
· Get some modeling software. Speaker Workshop is free, but a challenge to use. His best bet in the paid arena is SoundEasy, which is $250, which includes a full measurement and modeling tool set. It just a pain in the a$$ to use. LspCAD Standard is $220, but doesn’t include the extensive measurement capabilities of SoundEasy.
· He’ll need a mic too, like the Dayton EMM-6

Total cost: Somewhere between $100 and $350 depending if he uses free software or opts for SoundEasy/LspCAD.

If you're going to build Statements, go through the original thread after you start reading the books and understand the crossover development. Make note of what you don't understand and ask questions here.
Best of luck and have fun!

**Doc** · 08 February 2012, 13:43 Wednesday

Hey funkdrmr,

I'm Hank's bud from Dell, and former co-owner of Mirus Audio. If you really need some measurements, I think we can probably hook you up, it just may just take a while to find time in our schedules to make it happen.

It sounds like the bug has bit hard, though, so let me expound a little on Hank's previous comment. For a minimal investment, you can get up and running on your own, which will be much more fun and educational than just paying someone to give you some measurements. Here's what I'd suggest:

Get a copy of the Loudspeaker Design Cookbook. It's not perfect, but does cover all the basic theory and will give you enough understanding of how crossovers work that you can move on to more advanced books. As someone else mentioned above, the key to understanding crossovers is understanding the basic electrical behaviours of resistance, capacitance, and inductance. Once you have those thre down, passive crossovers will become a lot easier. Also, there's nothing wrong with going active, e.g. MiniDSP. There's a convincing argument to be made that active crossovers are superior to passive ones in almost every way. Amplifier cost and complexity of set up being the only drawbacks. Plus, a DSP active crossover like the MiniDSP allows you to experiment with infinite variations without having to spend big money on parts. But I digress.

Next up, get a copy of Testing Loudspeakers. This is a fairly advanced read, so get comfortable with the LDC first.

I'm assuming you have a PC with a soundcard already, so for hardware you just need a decent mic, like the Dayton EMM-6, which is a killer value for $50. Using REW and your woofer tester, you should be able to get the basic frequency and impendance measurements you need to create passive or active crossover designs.

Along with the global 'net community, that's all you need to get started. A couple of books, a mic, and some free software.

Happy to answer any additional questions if you have any.

Doc

**funkdrmr** · 09 February 2012, 01:19 Thursday

Thanks, everyone. Doc, if there's any way at all we can get together that would be awesome. My schedule is nutty in the typical "I.T." sort of way, but I'd take a vacation day if that's the only way I had to make it work.

If it can't happen, I understand. There's certainly nothing wrong with grabbing a book, the mic & some software to get tweaking. I'm hoping to be done with the cabs in the next few weeks, so hopefully by then I'll have a bit more understanding than I have right now.

For my PC...yes, I have an M-Audio1814 with 2 preamps / phantom power, so I'm good there. I've been looking at REW as well & was thinking that might be a decent option to start with.

The MiniDSP has me VERY interested, especially since the interface is so similar to what I see in digital DAWs when I'm recording bands. It's the added cost of amplification that has me wanting to give passive a shot. Having a 3 way setup, I'm not sure how I can get 6 nice channels of amplification at a decent price point. Emotiva looks solid. I guess I could always go with Crown / QSC or something like that off the used market. Maybe I should research that a little more.

One question....I keep seeing information on measuring the speakers "outside", or in an "open field" type of scenario to eliminate reflections during the measurement process. Is that the normal method or is it acceptable to measure in the room the speakers will reside in?

**Undefinition** · 09 February 2012, 09:58 Thursday

Measuring loudspeakers is a science in and of itself. Before you go diving into that too, you might want to take a look at my writeup on how to "simulate" measurements.

Paul Carmody's DIY Speaker Pages

http://sites.google.com/site/undefinition/simulated-measurements

**Doc** · 09 February 2012, 11:36 Thursday

When you see references to measuring outside or in an open field, they're suggesting that for two reasons:

1) Accurate measurements require that the signal coming from the speaker not bounce off anything else in the environment before reaching the microphone. This is hard to do in a typical room. Most measurements, however, are made in doors, where reflections occur, so there are various mathematical techniques (e.g. FFT) for extracting the good data from the bad. However, when extract the good "pre-reflection" data, it will be low-frequency limited. Google search for an explanation of FFT for the details. This low frequency limitation is the other reason people test outdoors.

2) Groundplane measurements are a method of extracting usable low-frequency (typically below 300Hz) data without suspending your speaker 40ft in the air. To understand why this works, you need to look up steradians and the difference between 2pi and 4pi space. Not every project needs this kind of measurement, as low frequency behavior can be fairly accurately simulated by T/S parameter modelling. For speakers with low crossover points (such as some three-way designs) these measurements are needed.

Regarding simulating measurements...I personally haven't had great luck doing that (too much of a perfectionist I guess) but it would be a great way to get data you can use to learn how crossovers work. The link in Paul's post is a great explanation.

Let me know when you get your cabinets done - that's step one - you really need to measure the drivers in the cabinets. Otherwise you have to simulate their behavior in the final cabinets, and at that point you might as well go the full simulation method Paul described.

I'd be happy to do lunch sometime too if you want the non-engineer, back of the napkin explanation of how crossovers work. I did a few web searches for a good primer but didn't find anything as good as what's in the LDC.

Doc (Jonathan)

**Hank** · 09 February 2012, 14:24 Thursday

funkdrmr, for your six channels of amps, take a look at these class D's - I've seen recommendations for them: http://classdaudio.com/

**funkdrmr** · 10 February 2012, 23:21 Friday

Thanks, Hank. Those look very interesting & I hadn't heard of them before.

Doc...Thanks for clarifying the FFT stuff. I understood the reason (no reflections) and how reflections work in the room. Just didn't know if it more common or even "required" to measure in the outdoor (no reflections) environment.

I might start a "build" thread tomorrow after working on the cabinets some more. I took some pics already, and the bottom box is about 50% complete. I'm hoping on Sunday to tackle the pyramid (watt) cuts. I have a feeling it's gonna take a few times to get that right.

Let me know when you're available for lunch. Would love to sit down & chat.

**Doc** · 22 February 2012, 22:28 Wednesday

Hey funkdrmr,

Sorry for the reaaallly slow response. I'm free Tuesday and Friday next week if you still wanna grab some lunch. I'm up in Round Rock, where are you?

**funkdrmr** · 22 February 2012, 23:21 Wednesday

Hey Doc,

It's no problem. I've been slammed at work for 2-3 weeks solid, so I've barely had time to even think about this stuff.

Let's shoot for Tuesday if that's good for you. I work downtown, but it wouldn't be a big deal to head up your way.

First Post - Watt Puppy style project - crossover question

First Post - Watt Puppy style project - crossover question

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