View Full Version : Proposed 4-way way *PIC*
06-22-2006, 04:48 PM
Here's what I've thrown together so far in means of a 4-way speaker.
Tweeter: Vifa XT25
Mids: 2 RS125S-8 (295-360)
So far I've found the crossover points to be...
High pass for tweeter:
2nd order using 18 mic cap, .11mH w/ .11ohms DCR inductor
Low pass for mids (with reverse polarity):
2nd order .5mH w/ .32 DCR inductor, 33 mic cap
High pass for mids:
2nd order 200 mic cap, 1.5 mH w/ .43 DCR inductor
Low pass for woofer:
2nd order 4.5mH inductor w/ 1.18 DCR, 155 mic (using 2) caps
Low pass for subwoofer:
2nd order 8mH inductor w/ .3 DCR, 283 mics worth of capacitance
Conjugate filters on tweeter and mids.
Picture is of assumed response using PCD as if I were a loudspeaker manufacturer featured in Stereophile
06-22-2006, 04:49 PM
Here's a better view of what's going on
06-22-2006, 04:51 PM
Any phase shift created from an enclosure, baffle step, port output, or anything in terms of reality. Hey, it's a starting point!
06-22-2006, 06:47 PM
what made you choose the xt25, instead of a different tweeter?
06-22-2006, 07:04 PM
There were alot of reasons I suppose. Low Fs, decent sensitivity, great frequency response, great frequency range, low distortion, looks. It seemed to be THE complete tweeter. About the only average area seems to be transient response.
Also, the pair that I have are matched to about as close as I think possible, without having 50 sitting around to test. These have an Fs of around 490Hz.
06-22-2006, 07:59 PM
Don't let the low Fs fool you. These should be crossed no lower than 2khz.
> There were alot of reasons I suppose. Low
> Fs, decent sensitivity, great frequency
> response, great frequency range, low
> distortion, looks. It seemed to be THE
> complete tweeter. About the only average
> area seems to be transient response.
> Also, the pair that I have are matched to
> about as close as I think possible, without
> having 50 sitting around to test. These have
> an Fs of around 490Hz.
> Don't let the low Fs fool you. These should
> be crossed no lower than 2khz.
I've heard 3k. ;)
They can be crossed lower with great care.
Not a tweeter I would match to the RS125S-8.
Then again, the other drivers also make me scratch my head. :)
06-22-2006, 09:40 PM
Well shoot I really don't think you need a sub with if you use dual RS 10". You could probably even get away with using a dome mid. Cross the woofer no higher than 900hz using steep slopes--a notch will probably be required. Then use a nice 3/4" tweeter and make it a 3 way or 3.5 way with the woofers wired in parallel. If you going to spend this much time and effort you might as well do it right. You could also use a true midrange like a 6.5" PHL high efficiency driver to match the 96+db you will have with those woofer in parallel. This probably also puts you in the ribbon category or high efficency tweeter. Just my two cents, I know it rained on your parade but that's what I would do.
Well, I'll disagree with the not needing a sub part using RS270's. ;) They need silly big boxes to really hit the low bass ported. Do very very well sealed. Of course, I listen to music with content below 20Hz frequently (orchestra/organ) - for many (most?) genres, no sub would be needed.
I also am not sure it'll hit 900Hz comfortably, even steep.
There are reasons I went the way I did (and Brian, since he picked drivers - I would probably have gone RS150 instead of RS180, but am not disappointed...)
06-22-2006, 10:40 PM
Ok, I try and keep track of everything said on the board but its hard sometimes. Are you referring to the ones CurtC designed the crossover for? Give me a link for referal if not as my memory has failed me--again.
06-22-2006, 11:21 PM
Thanks for the input! I wish I could find a way to fit a picture of the PCD full screen view in here to show all of the info. I started with the XT25 target set at 3kHz, the RS125's at 2kHz and 250Hz, the RS270S-8 at 250Hz, and the RS15HF at 75Hz. Though the textbook values were heavily tweaked.
My goal for the crossover was lowest possible non-linear distortion, narrow bandwidth for each component (reduce intermodular distortion), as close to transient perfect in the upper bass/midrange/high area as possible, and lowest possible parts count for a 4-way design. I've heard alot about domes having larger amounts of distortion than cone drivers in the midrange area, and my crossover goal for the mid was too low for a dome (knowing I would sacrifice off-axis response).
The choice of two woofers allows me to sidestep baffle step (for now). The HF is probably going to reside in a very large (9 cubic foot) enclosure with an F3 of ~17Hz.
I'm just trying to come up with a set of mains for two-channel listening that rivals the bandwidth of anything currently on the market.
I'm planning on using a hybrid fiberglass enclosure that contains a mixture of MDF dust.
It's still very much in it's embryonic state, but I've been working on the mid/tweeter alignment for months (not that I have anything to show for it yet other than matched drivers).
Please keep firing away at the design as I am always open to change (ie. filter alignments).
The AR SXO I am using appears to be between 2100 and 2600, and I haven't played them as intended yet. The Nebula used a 2.3kHz AR SXO, so I'm not far off. I think most actually use a 2.5k in their designs.
06-23-2006, 01:40 AM
If you like to listen to really loud music I wouldnt use dual RS125's. They can go fairly loud but then distortion hits them, at that point they can only go about 10% louder before they totally crap out. I have mine crossed at 300hz and 2500hz 2nd order slope. Perhaps dual RS150s would have better power handling but maybe a tiny bit less imaging.
BTW I have a 150wpc amp just for perspective.
And as far as imaging goes, I have another set of speakers that use dual 6.5" classics and they image better and sound more natural than the RS125's. I have never used the RS150's before so you might want to ask people about them before you take any of my advice.
06-23-2006, 08:21 AM
Do you have a high pass filter on them?
> Ok, I try and keep track of everything said
> on the board but its hard sometimes. Are you
> referring to the ones CurtC designed the
> crossover for? Give me a link for referal if
> not as my memory has failed me--again.
Nope. I think you have the RS225/RS150/RS28A WWMT 3-way tower in mind/WTMW center project in mind.
I was referring to the 3-way towers I designed for Brian (based on his driver choices). WWMTM. :)
All too well I know the feeling of losing track of projects. In fact, I had to go review what I had said to even respond to you.
Provided Link: RS 3-way WWMTM towers (http://htguide.com/forum/showpost.php4?p=203855&postcount=537)
Having given this more thought...
Ditch the RS125 for the RS150. Target 1800Hz 4th order. 2100Hz is not bad 4th order, so you could go there - not much higher IMHO. No notch required for either IME.
Switch to RS225's instead of RS270's - still sealed, still low Q. This will work better with a lower slope crossover should you chose that route, and the big RS subs can go high enough clean that the 270's are IMHO a bit more than required.
ANOTHER option: have you seen the 3-way towers I've done? WWMTM with dual RS270's, dual RS180's, RS28A. I believe the XT25 could be snuck into this design, though it would not be my choice. But IIRC only the impedance compensation (i.e. flattening) will need to be tweaked - Jon Marsh has explored swapping tweeters around some, and I"m pretty sure he found RS28A could drop in where the XT25 was. I HAVE NOT VERIFIED THIS today. :) Anyhow, add sub, and you have a killer project (which is one of the things I am currently trying to figure out how to do). ANd most of it done already.
If nothing else, it's a point of reference you can use - certainly am open to answering questions.
06-23-2006, 01:21 PM
(Originally posted by: Rob <email@example.com>)
06-23-2006, 01:38 PM
I appreciate the suggestions, only I have the RS125's that are all matched, and I don't want to start completely over from scratch in the tweeter/mid section. I see where you are coming from, but the fourth order crossover and increased sensitivity will increase parts count and complexity of the design having to deal with the extra energy in the passband.
You can probably get away with 2nd order - Dennis Murphy seems to think so with the RS150. I'm not convinced, but that's me - and everyone has slightly different ears. :)
I would still go RS225 - going to work better with the RS125's by a long shot. Maybe move up to 400 or 500Hz 225 to 125
06-23-2006, 03:51 PM
Now we're talkin'! That's where was I was wanting to cross in the first place! I appreciate your patience with me not wanting to switch out the mids. The 10" was rather hard to work with in relation to the RS125's, and I had to redesign a closer to transient perfect XO from the mid to the tweeter. Let me play with that awhile. Thanks again!
06-23-2006, 04:03 PM
Now I recall your design :-). A picture is worth a thousand words. Nice looking speaker.
06-23-2006, 06:33 PM
Just kidding, the 8" is alot easier to work with, thanks for the idea!
06-23-2006, 06:35 PM
Not too shabby
06-23-2006, 06:40 PM
Looks pretty good to me, what you think?
06-23-2006, 06:45 PM
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