Heavy OB

[RCruz]

Hi All

I am trying to make corrections on the crossover for my friend´s OB that uses the following drivers:

Two Woofers Beyma SM115/N
15in
8ohm
98dB sensivity
30-3kHz
29Hz resonance freq

One Mid Supravox 215 RTF 64
Full range 50 ~10kHz
8 ohm
97dB~100dB sensivity
60Hz Fs

One tweeter B&C DE250
8ohm
108.5dB sensivity
Response 1 ~18kHz


As I am not used to tune crossovers and am quite noob about these matters, I hope I can get some guidance here (I am used to that in diyaudio.com)

Actually I have one 1,2uF cap in series with the tweeter, one 4,7mH coil in series with the two woofers that operate in parallel and a "contour filter" in series with the mid (4mH // 35ohm).

The trebble is way too proheminent and there is a serious lack of bass.

In loud drum passages the supravoz reaches it´s limits and sounds compressed.

I believe the best compromise would to cut the woofers at 200~400Hz and let the mid go from there to 16kHz where the tweeter should fill the gap.

I downloaded lspCAD6 Lite but can not understand how to input the drivers specs so ....
What should I do ?

Best regards

Ricardo

[Cal Weldon]

Hi Ricardo,

You are just beginning to find out how difficult working with multi-way XO's is. To be honest, if you're rather green, the best thing to do it is go active. Look up the active crossover options here on the net from the dealer closest to you. Active XO's are not as expensive as the route you are about to take.

[ttan98]

I am building an OB speakers now, the procedure to get a successful OB working properly, it much easier to go active and if you like later design passive x-over for your speakers config.. Depending on your speakers config. and spec and baffle width, it may be difficult to get the x-over right using just passive components alone.

I use DCX2496 as my active x-over(it has a built-in DAC as well), I can EASILY configure my system Xover based on the DCX. When I like the sound I can design a passive x-over for tweeter and Mid range which I am doing now and then extend to mid range and woofer as well based on the DCX setting. You must also get a microphone and measuring s/w like ARTA FOR FREE to make sure the FR is correct off and on axis.

BTW I use a commercial s/w to design my x-over however there a few free x-over s/w(very good one as well) floating around.

The is no short cuts but learn how to use these s/w and it will take time, that why this is a hobby.
Cheers happy building and designing.

[RCruz]

Hi Cal
I know going active would solve my problems but that means more than 1 power amp so I can not do it.

Hi ttan98
Would you point me a good software that I can use ?

[jerome69]

Hi Ricardo !

Agree with the responses. Active is much easier. At least the part woofer-midrange.

The crossover depends on the geometry of the panel. Can you show us the plan ? the dimension ? a photo ?

It is possible to make something passive but very hard. The woofer seems not match on the paper with passive OB requirements (Qts>0.5).

Troels OB7 monster : OB7
Your friend 'sproject could work if the panel is as large as 1m

Regards

[Ang]

Ease your troubles dramatically and at least go active on the bass... maybe just use sub amps with built variable high pass. Then design a two way passive for the mid and tweeter so you can run them both off your SET or whatever and make use of their high efficiency.

again, I'd vote with everyone else for all active.

[Helmuth]

Originally Posted by RCruz

Hi Cal
I know going active would solve my problems but that means more than 1 power amp so I can not do it.

Hi ttan98
Would you point me a good software that I can use ?

On dutch audio forum there are a lot of guys who use a low cost active cross over of behringer an class-d modules of Hypex to build OB.

Good coils and capasitors are cost the same as the perfect class d amplifier of hypex. A listened to the amp connected to magnepans sounded perfect. Impedance in depended behaivour and low and constant THD does not increase with power.
Hypex Electronics B.V.
BEHRINGER: DCX2496
http://www.hypex.nl/docs/UcD180HG_datasheet.pdf

[RCruz]

Ok

I agree with you but my friend is very stubborn.

Hi Jerome... would you give me a hint about min Qts for an OB ?

The OB my friend built are 1,8 meters high but only 50cm wide and worst of all, the lower woofer is almost sitting on the floor.

I would be very happy if I could design a propper crossover for the mid / tweeter.

I will study the hypex power for the woofers after that.

Can you please guide me into a good mid/high crossover ?

I already read about OB with the supravox in this site: http://www.troelsgravesen.dk/SupravoxDTQWT.htm

And got some ideas about baffle interaction here: http://www.quarter-wave.com/OBs/OB_Design.pdf

[cuibono]

Do you have a measurement microphone?

I don't want to discourage you, but trying to do this crossover without some way to measure what you've done is practically impossible, especially for a neophyte...

[Helmuth]

Originally Posted by RCruz

Ok

I agree with you but my friend is very stubborn.

Hi Jerome... would you give me a hint about min Qts for an OB ?

The OB my friend built are 1,8 meters high but only 50cm wide and worst of all, the lower woofer is almost sitting on the floor.

I would be very happy if I could design a propper crossover for the mid / tweeter.

I will study the hypex power for the woofers after that.

Can you please guide me into a good mid/high crossover ?

I already read about OB with the supravox in this site: Supravox DTQWTSupravox 215RFT-

And got some ideas about baffle interaction here: http://www.quarter-wave.com/OBs/OB_Design.pdf

It is easy to calculate a XO for you theoretical, but I know it will have a lot of short comings because what is the efficiency of the suprafox in a OB what is the effect of the baffle on the response. And the response of that driver isn't flat that makes things not easier.

Then only way is to measure what your output is, and then optimise the XO. I can measure what I have build and worry about projects how are build only on theory. Little chance that you get a good result.

Did you read this analogue XO.Behringer CX2310?
When you build active it will be much more easier to change things and in the end will be less expensive.