Series xover design

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I would like to build a small 2 way MTM speaker and incorporate a series crossover. I can only find limited information on series xovers and I'm wondering if anyone has any real experience or knowledge using them. Any help would be appreciated
 
You might find this useful:
http://www.acoustic-reality.com/ar-sxo.htm

The designer shows how to tune the xo, but the method used is based on trial & error methodology. I haven't tried the xo, but I am going to give it a shot someday. I'd like to try this serial xo on Lynn Olson's Ariel speakers.
Say.... has any soul in this world try serial xo on Lynn Olson Ariel speaker?

-The Great Saiyaman-
 
help with ideas

I am planning to build a smal speaker with a small sub (if you can call a 8" woofer a sub).

The small speaker will have a 6" Vifa woofer and 1" Vifa tweeter (models TC18WG49 and TC26TG05) the specs can be got from http://www.d-s-t.com/vifa/index.htm.

below this speaker I intend to add a small 8" woofer (active).

The 8" will provide bass reinforecement and also compensate for some difraction loss. The 8" woofer is a repaired Eminence woofer approx TS specs are Fs=35Hz and Qts 0.45. The cabinet of this woofer will act like a stand for the 6" 2 way described above.

1. can I use a 2ay 12db series XO with the Vifa drivers.

2. To make the cabinetry simple I intend using 4'x8' sheets of MDF and making the height of the speaker 4' (48"). Is this too tall? Should I put the 6" on top of the 1" so that the 1" can be closer to listening height (36-38").

3. At what height on the baffle should the 8" be? Roy Allison claims it should be as close to the ground as possible, else where I hear the center of the bass driver should be 16" (40cm) from the ground. And my common sense tells me it should as close to the 6" 2 way as phyisically possible so that all the sound is coming from as small a point as possible.

4. I intend to bend the cabinet side walls a la Sonus Faber Amati and Wilson Benesch Act 2. How thick a MDF can I bend. If the MDF is less than say 8mm (so that it is easier to bend) should I use layers. If I am using layers can I use lead sheet 2-3mm between the layers?

5. I intend to bolt the drivers to the cabinet instead of using screws as I want to integrate the drivers as solidly to teh cabinet as possible. Does is make sense to veneer the cabinet so that the bolts are covered/hidden. What are chances I burn a woofer or tweeter out. Usually I hear only tweeter burn out.

6. The baffle will be 30mm MDF. Since I am bolting the drivers shold I use a 3-4mm metal plate on the inside of the baffle so that the bolt does not bite into the wood?

7. I intend using a truss rod for each of the 6" and 8" drivers. The truss rod will be a plastic or metal tube filled with either lead shot, sand or thermacol pellets. Which combintion wouldone recomend?

Since I do not have regualr access to the net please email me at navin@vsnl.com

Regards
Navin
 
4384

1)sounds like you'd need some modeling and luck for a series to come out ok. You might think about building a test box and trying some different crossovers to see what you like before you commit. Can you do any modeling?

2)be careful of resonances between surfaces. The long length from top to bottom will need some attenuating-foam, etc.

3)the mid and tweeter need to be close together since they're higher frequency. The lower frequencies are fairly non-directional, so you can move it closer to the ground for more gain. What's your crossover frequencies?

4)you can always build up layers of MDF. You'd have a better chance of bending, and it would be more stable once glued.

6)I've used screws directly in MDF. As long as you don't screw them in too many times it works ok. There's also T-nuts that go in from behind and you use a bolt in to it. They bite in to the MDF to hold them (supposedly) from turning. You could always try a screw, then use T-nuts if needed.
 
yes long surfaces need a lot of bracing.

i expect to XO at about 120Hz and 2-3kHz.

Actually I am hoping to use a 2kHz series XO with a zeta of 0.7 (slope of 9db/octave) between the 6" and 1"

the 8" will rolled of at about 12db with a electronic XO at 120Hz. I hope to use the XO inside my HT amp (I hope to use the subout signal for the 8"). The 8" has it's own power amp.

The 6" 2 way will be a full range speaker the 8" is there for bass reinforcement and to compensate for SOME of the difraction loss. This way I can get away with a series XO and some other passive (using difraction control techniques on the cabinet) methods to compensate for difraction.

3 layers of MDF (6-8mm) with a leyer of lead (1.5-3mm) between them is what I am looking at.

hope this helps

cheers.
Navin
 
I use series x-o exclusively , from choice !

If you don't have all the measuring and x-o sim software, with the right drivers and a bit of time you can nearly always get a better sounding speaker by using a series cross-over. The idea is to keep it simple.

The main point with series x-os is that if you get the values slightly wrong, all it does is alter the slope and x-o point slightly. If you download the series x-o spreadsheet from my web site, you should find it gives you a pretty reasonable starting point, and if I remember off-hand, the Vifa drivers you mention are well suited to use of a series x-o.

There are also a couple of tricks that can help overcome some driver problems, and also a neat little trick that allows for some baffle step compensation just by altering the values a bit.

If you need any help with getting something up and running, just email me !!!

my web site is at http://home.iprimus.com.au/gradds/

:cool: SERIES X-O's RULE!!!:p
 
hello andy ;)
You tested the function of the calculation of the crossover series in LSPCAD?
I find that excel;)
It is necessary re-entered the files of measurement FRD and ZMA then one can see the curve reality I made tests in MTM with two vifa p17wj and a tweeter D27TG and the result are excellent and confirms well what the software gives me;)
Mezzo;)
 
Andy_G

Hi mezzo,
the only measuring equipment I have are my ears.
Ken Perkins has used my series x-o spreadsheet a lot and then measured the results. I most cases he has found that the spreadsheet is accurate to within a couple of hundred Hz, even different zeta giving the desired changes in the curves.

The spreadsheet relies on having smooth driver response, all that is entered is the sensitivity, and impedance of the drivers. It is due for a revamp, because i want to remove the LR baffle step compensation section, cos using the LR method sucks the life out of the speaker. Also I tend to use different L-padding than indicated in the spreadsheet, so need to alter that section a bit. Its all done on a "what i use that I think sounds best" principle !

I know it ain't the bee's knees, but its a good starting point for those without other software.
 
Yes the worksheet allows a very good approach of the final result but the response curves of the loudspeaker are not really linear and can have peaks or hollows, and software favours it and to see this;)
Now, your worksheet is really excellent for that which does not use software;)

good night, it is 1h00 morning in France and I must sleep;)
Mezzo
 
can i use the Vifa drivers mentioned with a series XO having zeta of 1?

I prefer a laid back sound but a zeta of 1 gives a 6db/oct roll off and I am afraid the woofer will break up and the tweeter will blow.

from what I can see I would have to use a zeta of 0.7 (9db/oct roll off) at 2000Hz.

let meknow if anyone has a better suggestion.

thanks again all.

regards
navin
 
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