Yet Another DIY Xover ?

[iain42]

Ok I was trying to make things too difficult last time I attempted this but I need a different xover to try. I'm using a steep slope currently. I'd like to step back and compare to a simple first order then a second order. Also I'd like to try crossing higher than I am currently.

I usually just buy crossovers but this time that isn't possible. This is for a two way system so at least there is only one crossover point to deal with. I'd like to try a first order at 600hz and 800hz.

I was told the drivers were 8ohm but I got my trusty multimeter out anyway and measured the altec HF @ 6.7ohms. The bass bin is a folded bass horn with two twelve inch drivers. One woofer measures 5.7ohms. There are two and together they measure 2.9ohms. They aren't wired together but do go to the same terminals on xover. From cossovers to tube amp they are on the 8ohm taps.

If I use the online crossover calculators what numbers should I use to arrive at proper crossover points and purchase the right inductors and caps? Do I have enough data to proceed? Am I making this harder than it is? Any advice is appreciated.

My girlfriend actually ordered me a behringer pcm mic and mic preamp so I can quit talking about getting this system where I want it or at least get the room treated properly. I'll at least have some tools to compare to my ears. Trust but verify. I may just end up where I started but I gotta try.

 

[planet10]

Lets start with what drivers & what box... pictures?

some comments:

A driver that measures 6,7 ohm (Re = DCR) is what you would expect for a nominal 8 ohm drivers, The impedance of a driver is far from a straight line,

The bass drivers are wired in paeallel... you;d be better running them off the 4 ohm tap.

dave

 

[iain42]

Hi Dave,

I'll try the 4ohm tap.

The HF is an Altec 511B/Altec 902-8 by Great Plains Audio. The box is a clone of Klipsch's last folded horn design which never saw consumer release. It has two 12 inch drivers k-31 but I have no specs on them. Each driver in the bass bin has it's own binding post on the top of the cabinet. Then they are wired to the same neg pos terminals on the current crossover.

The HF 511B sits on top of the cabinet like the very early klipschorns.

I have always used fairly simple networks so I want to compare first order to what I have now which is steep slope. Also I wan to try to cross a little higher. The part count is minimal so why not.

Here is a pic I found of the cabinet. Someone did a google sketchup of it. The dog house is in the middle.

Thanks

 

[phase_accurate]

OT:

From your CAD I guess that you intend to use this free-standing (i.e. not in a corner). Am I right ?

Regards

Charles

 

[iain42]

I do have them in corners but they are not dependant on corners like the original klipschorns. They are more flexible but of course yield better bass in the corner. If I move I don't have to worry about the room as much.

 

[tinitus]

http://www.pispeakers.com/Speaker_Crossover_Lab.doc

I suppose some of this could be usefull

Somewhere in the middle there should be some tricks about how to cross a CD properly...from what I understand its really very important to know how to use these

 

[gedlee]

I think that its important to stress how difficult a truely well done crossover is to do. Wayne's paper is interesting, but its just the tip of the iceberg. Its worth reading to learn where to start, but your not going to do a world class crossover with that information. The whole DIY thing falls down at the crossover because it is a seriously difficult problem. I appluad anyone who wants to learn, but don't expect that your going to be able to do anything but the simplest designs without a lot of time, equipment and experince.

I really have to chuckle when I see these canned crossovers - one design fits all. And then when I learn how many of these they sell. Wow, its just not that simple.

 

[iain42]

I think that its important to stress how difficult a truely well done crossover is to do. Wayne's paper is interesting, but its just the tip of the iceberg. Its worth reading to learn where to start, but your not going to do a world class crossover with that information. The whole DIY thing falls down at the crossover because it is a seriously difficult problem. I appluad anyone who wants to learn, but don't expect that your going to be able to do anything but the simplest designs without a lot of time, equipment and experince.

I really have to chuckle when I see these canned crossovers - one design fits all. And then when I learn how many of these they sell. Wow, its just not that simple.

Somehow this was the answer I was afraid I would get. The more I read the more confused I get. I have the settings if I decide to go active which may be my only other alternative. What I have works well but I was wishing to crossover a bit higher but mostly for experimentation. Also I wanted to compare steep with gentle slope. You see the numbers seem to indicate this cabinet could go out to 800hz and drops like a rock at 1000hz but I haven't heard this for myself. It could sound bad out that far. I may still coble together a simple first order but it will be just an experiment.

Thanks