# Help to a noob. Speaker exp.



## mgboy (Jan 17, 2007)

I've been trying get a standard 2nd order crossover designed using this woofer -

http://www.partsexpress.com/pe/showd...number=264-850

and this tweeter

http://www.partsexpress.com/pe/showd...number=264-840

just to see what could be made on the cheap. As of the moment I'm using some high end Pioneer "bookshelf" speakers ( brushed aluminum plates, L-Pad, accordion surround, etc ) from the 70's that my dad gave to me, and they sound great to me, but I've been using them for quite a while and building my own speakers sounds interesting to me, but I'm not sure where to put the "lowpass" and "highpass" (per say) for the crossover. Should I have the "high pass" on the tweeter higher than I put the low pass? or the same point? Since that woofer is useful up into the 5-6k Hz (maybe) due to the phase plug, I can cross the tweeter higher, but I'm not sure where to put them. I can find the components fine, and can find out the values of the capacitors and inductors I'll need ( winISD ) I just need some advice on where to start the steps, and if a 1st order could work, that would be fine with me ( just less money ) but I don't know how to properly implement a crossover. I don't need anything fancy,because I'm trying to keep this down, unless it would due wonders and not cost but a few bucks more.

Thanks


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## Geoff St. Germain (Dec 18, 2006)

I would suggest getting a book like Vance Dickason's Loudspeaker Design Cookbook. It provides an overview of crossovers. 

You can also check out this excel spreadsheet:
http://www.pvconsultants.com/audio/crossover/pcd.htm


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## BoomieMCT (Dec 11, 2006)

Can't say 100% without testing the drivers but I think drivers have better dispersion when crossed as low as they can play without distortion. Without doing testing, looking at the manufacturer's specs can give you an idea of where to cross. Looking at the specs for the 13-1264SE it looks like it is flat down to 3kHz where it then falls on its face. Not surprising as it has a fairly high Fs of 2300 - 3000 Hz (depending on if you believe PE's or TB's numbers). I probably wouldn't cross it below 5 or 6 kHz with anything less than a second order filter (one cap in series, one inductor in parallel). The steeper the crossover the lower you can cross it at. 

The woofer you selected can probably play high enough to mate with it. There will be a bit of beaming from 2 kHz - 5kHz. 

So, assuming you are going to cross both drivers with a second order crossover you will need two capacitors and two inductors. You'll probably need to pad that tweeter down a bit. An L-pad would work well for that (2 resistors). You may or may not need a zobel network to get the woofer to cross over better, so that's another capacitor and a resistor. Finally, depending on where you are going to set these up you may or may not need a baffle step compensation circuit. Throw in another inductor and resistor for that.

That's a lot of parts! I'd start with a simple crossover and an L-pad to bring the tweeter down. I'm a fan of buying extra electrical parts so I can build crossover componants to test and play around with.


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## mgboy (Jan 17, 2007)

Would a first order just not work as well with it crossed so high? 

What can you do about the woofer beaming that high up?

I was thinking of a ~2.2-3 L-Pad on that tweeter, using a 20ohm resistor and a 1+.33 ohm resistors.

** Also note, I could go with a better (more expensive) tweeter, if it would allow less crossover parts, I can juggle prices, but needs to stay cheap.


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## BoomieMCT (Dec 11, 2006)

There might not be a problem, I wouldn't know without playing with those drivers a bit first. I was just giving a first guess based on my experience. I'll handle these in pieces.

1. Woofer beaming: The woofer will probably beam to some extent above 2kHz because it is a 5 1/4" woofer. The larger a cone is the lower frequency it will beam at. The phase plug should help with this somewhat. Whether this is an issue or not depends on the listener. I have spent plenty of time listening to 3" and 4" single driver speakers and I'm happy with them. My friend Anthony (who is more of a tweeterhead) is not. Tastes vary.

2. 1st order x-over: You can try using this. The tweeter seems to want to drop off below 3kHz, the woofer above 5 kHz. If you put the x-over halfway between those points that means the tweeter will only be down 6dB @ 2kHz and the woofer down 6dB @ 8kHz. The woofer shouldn't have a problem with this, the tweeter might. In my limited experience you need (expensive) drivers with wide bandwidth to pull off first order crossovers well in a 2-way speaker. Check out this page and see if any of the other tweeters in your price range grab your fancy. Just off specs (I have no experience with it) the Hi-Vi TN25 looks like it might be a better match.


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## mgboy (Jan 17, 2007)

I don't mind the looks of that tweeter, and it does seem better matched but I say the HiVi Q1R looks a little better, and the HiVi SD1.1 caught my eye on that list of Zaph's.


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## mgboy (Jan 17, 2007)

mgboy said:


> I don't mind the looks of that tweeter, and it does seem better matched but I say the HiVi Q1R looks a little better, and the HiVi SD1.1 caught my eye on that list of Zaph's.


Found measurements of the HiVi Q1R on their website here - http://www.swanspeaker.com/product/htm/view.asp?id=25 and the TB page is here - http://www.tb-speaker.com/detail/1208_03/w5-704d.htm ..

With a lower fs, and wider response, that Q1R seems like it could do just fine 1st order with that woofer. 4000ish seems like it wouldn't kill the better tweeter. Idea's? 

I'd take a look at that excel spreadsheet but I can't find my Office CD at the moment.


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## BoomieMCT (Dec 11, 2006)

If the Q1R's Fs is 1000Hz you should be okay with a 1st order x-over at 4000 Hz as it will be 12 dB down by the time it hits it's Fs. That being said I wouldn't go much lower with a first order crossover.

The best thing to do now would be to take the FR and impedence plots from the Hi-Vi and T-B sites, put them into Passive Crossover Designer and play around. That will help you nail down your crossover componant values and give you and idea of what kind of performance to expect. With a first order crossover pay close attention to the phase graphs.


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## mgboy (Jan 17, 2007)

BoomieMCT said:


> If the Q1R's Fs is 1000Hz you should be okay with a 1st order x-over at 4000 Hz as it will be 12 dB down by the time it hits it's Fs. That being said I wouldn't go much lower with a first order crossover.
> 
> The best thing to do now would be to take the FR and impedence plots from the Hi-Vi and T-B sites, put them into Passive Crossover Designer and play around. That will help you nail down your crossover componant values and give you and idea of what kind of performance to expect. With a first order crossover pay close attention to the phase graphs.


That's what I was thinking.

and if I was able to open the PCD ( i can't find my msoffice cd ), how would I implement those graphs in? and how is one supposed to read phase graphs? I've never known what exactly they mean I just know that I was graphing things similar to that in my Pre-cal class the other month.


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## BoomieMCT (Dec 11, 2006)

I open a example FR and impedence file in excel, fill in a few points off the manufacturer's graphs and use the series fill to fill in the points. I then save it as a .frd file and import it. It's tricky the first time you do it, easy every time after that. It is important to get the frequency AND impedence plots in there as both affect crossover values.

When you finally get a FR you like, look at the combined impedence plot to make sure you aren't going to kill your amp.


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## mgboy (Jan 17, 2007)

BoomieMCT said:


> I open a example FR and impedence file in excel, fill in a few points off the manufacturer's graphs and use the series fill to fill in the points. I then save it as a .frd file and import it. It's tricky the first time you do it, easy every time after that. It is important to get the frequency AND impedence plots in there as both affect crossover values.
> 
> When you finally get a FR you like, look at the combined impedence plot to make sure you aren't going to kill your amp.


I hate to sound dumb but, you lost me.


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## BoomieMCT (Dec 11, 2006)

If you look through the folders (after unzipping PCD) there is one that has some .frd and .zda files The .frd files are FR files, the .zda files are impedence files. All the FRD Consortium products run off these files.

If you open one in Excel you will see three columns of numbers. For FRD files the first is frequency, the second is the response and the third is phase. For ZDA files the first is frequency, the second is impedence at that frequency and the third is phase.

What I do (and I'm sure there is a better way) is that I open one of these files in Excel. Now you have everything nicely sorted into columns. Clear the second column and fill it with the data from the FR or impedence graphs you looked up from the manufacturer. Save it as a different name and repeat for the tweeter.


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## mgboy (Jan 17, 2007)

Oooh gotcha. Thanks Boomie, you're a big help. I'll get on that today and see what it looks like. If the impedence is going to be to low (lower than 4 ohm) what could I do then?


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## BoomieMCT (Dec 11, 2006)

I get impedences to drop too low when the x-over for one driver is at a different point or at a different slope then the other driver or if one driver has a steep impedence plot. There are a few things you can do.

1. Play with the x-over points until there is no dip.
2. Add a zobel network to whichever driver has the steeper impedence at the x-over point (PCD has an "auto zobel calculator" which is nice) and see if that fixes anything.

Some people think a very narrow dip isn't that important. I try to avoid them anyway. Generally for an 8 ohm speaker dips to 6 ohms isn't that bad. I wouldn't go below that though.

Once you get your .frd and .zda files I highly suggest playing with PCD a LOT. That is a good way to learn as you can add componants and see how what they do to the FR and impedence plots.


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## mgboy (Jan 17, 2007)

Well I tried making my own .frd and .zda files, but I think I either chose too few points, or didn't do something else right, because when I opened them in PCD everything looked very drastic and screwy. How many points should I put in? and if I put too few, shouldn't it just connect the dots? It could takes hours and hours to fill in 1 .frd file if I have to put a bunch of points..


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## BoomieMCT (Dec 11, 2006)

I have noticed that if _I _pick the frequency points this happens. That is why I always take an existing FRD or ZDA file and only change the last two columns. I usually put in 1-2 dowzen points and then use Excel's "fill --> series" function makes this not too difficult. 

I have no idea why this is the case. 

If creating your own FRD and ZDA plots becomes too bothersome (for now) you can generate the same plots in Unibox and export them.


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## mgboy (Jan 17, 2007)

BoomieMCT said:


> I have noticed that if _I _pick the frequency points this happens. That is why I always take an existing FRD or ZDA file and only change the last two columns. I usually put in 1-2 dowzen points and then use Excel's "fill --> series" function makes this not too difficult.
> 
> I have no idea why this is the case.
> 
> If creating your own FRD and ZDA plots becomes too bothersome (for now) you can generate the same plots in Unibox and export them.


Well the unibox was easy.. but for the tweeter I'm assuming I'm just going to have to pick some points, as nothing I know of will model tweeter frq. and imp.. yeah?


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## BoomieMCT (Dec 11, 2006)

Yeah, tweeters are a pain. As another FYI many drivers on the PE page have Clio response files. These are super easy to make into .frd files.


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## mgboy (Jan 17, 2007)

After searching a bit, the Dayton "Silkies" seem like a good (better?) option than the HiVi's..


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## mgboy (Jan 17, 2007)

I'll post updates after Christmas if I get them built.


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