Drivers / parameters for ripole subs

[soundcheck]

@calvin:

What else is new. How many times has this been mentioned?

What's your point?

Let's call it "LIpole", for Linkwitz-pole.

Look at the Linkwitz approach. He just opened up his knowledge and made it
available the world. And even allowed Ridthaler to file his patent.
Would be interesting to see a comparision of the number of implemented Orions vs.
commercial Ripoles.

What I don't like about patents and its license fees:
They can prevent real good ideas from being spread to a wider community.
The good thing though - They won't prevent technical progress. They actually push it .


Great to be in the DIY and Opensource world.

I havn't seen very many installations with less then 4 (four) 12" drivers per side lately!
Again - IMO the biggest problem of standard Lipoles and Ripoles are their low efficiency.

Equalization etc. is not any issue at all if you run them with a Behringer DCX 2496 or brutefir. I cut mine off with 48db at 110Hz. Perfectly matching my Bastanis Apollo Drivers.

The widely beloved "full" mids suddenly become clean and precise mids.

Cheers

 

[chrisb03]

Equalization etc. is not any issue at all if you run them with a Behringer DCX 2496 or brutefir.
Cheers [/B]

Is there a user friendly windows based software package?

 

[Moondog55]

Chris isn't combining the words "Windows" and"userfriendly" an oxymoron especially XP and Vista.

 

[soundcheck]

Checkout this one:

http://www.thuneau.com/allocator.htm

 

[head1962]

Hi.

The dimensions I applied for my 15'' BD15s are:

All in mm:

W:355*H:455*D:455

Center opening is 80
Wood: 18

The whole cabinet is obviously not vibrating.
Putting them on spikes though delivered much more refined sound.

The tricky thing was to get both holes (driver and magnets) on the same center-axis.
At the same time the gap between magnet and wood I didn't want to have greater then 2mm. This way I could use 2 layer of sealing tape to get it properly sealed.

As you can see the speaker-size for 2 * 15inch drivers is ridiculous small.
I'd always recommend to go for 15inch drivers.

Good luck.

Hi,
is there a (good) reason for the magnets to stick out?
If you'd have "flatter" speakers, could you leave the speakers all inside?

Thanks

 

[chrisb03]

Hi,
is there a (good) reason for the magnets to stick out?
If you'd have "flatter" speakers, could you leave the speakers all inside?

Thanks

The only reason is so that it keeps the enclosure as small as possible whilst maintaining the correct opening on the front and back.

 

[chrisb03]

Checkout this one:

http://www.thuneau.com/allocator.htm

Looks good. But I suppose a good quality sound card would be very expensive. Therefore just buying the Behringer 2496 would be cheaper anyway. Having said that, not sure of the quality of the analog out of these things is anyway.

 

[soundcheck]

Nothing that I am aware of. You save 60mm width and it IMO looks cool.

Cheers

 

[Rudolf]

... is there a (good) reason for the magnets to stick out?
If you'd have "flatter" speakers, could you leave the speakers all inside?

The backside volume of the ripole enclosure is less critical than the front one, that´s true. But you should try to make it not much larger than double the front volume. (If you add the volume inside the cone to the front side air volume and substract it - plus magnet and basket - from the back side volume, you still will have comparable air volumes on both sides of the driver.)

Most people who want to keep the driver completely inside the enclosure haven´t thought about the pole piece venting. Drivers in ripoles will move some air. Therefore blocking off a pole vent with the side wall of the enclosure is bad. You will at least need an inner distance to the side wall equivalent to the diameter of the pole vent. How flat needs a driver to be to allow for that?

 

[chrisb03]

(If you add the volume inside the cone to the front side air volume and substract it - plus magnet and basket - from the back side volume, you still will have comparable air volumes on both sides of the driver.)

Is that what we should be aiming for? 50%/50%? or should the back volume be slightly larger, say 45%/55%?

 

[soundcheck]

Just a quick thought.

The backvolume is 100% bigger (distributed on two drivers ) anyhow.

 

[chrisb03]

I found this post:

http://www.audiocircle.com/circles/index.php?PHPSESSID=nhvktgls2trsahfderq1ik0gt2&topic=54844.20

Mentions placing a "U" in the centre cavity improves the design. Does the front opening change if this is implemented?

 

[Rudolf]

A ripole consists of two transmission lines - one on the front and one on the back side of the speaker cone. Those TMLs should not have wildly different parameters. While both TMLs feature the same physical length, there has a correction factor to be added for the virtual/ effective length of the line. That correction factor depends on the opening area.
Added to that both sides of the cone see some air trapped in the cavities, resulting in an added mass load. Its easy to see that this mass load (and its effect) will be very different for front and back, simply because ot the highly non-symmetric driver construction.

Now you can make rocket science out of this, take one of those weather forecast number crunchers, do an in-depth-FEM simulation for those TMLs and get your perfect ripole.
Or you just try to not have double the values on one side of the cone than on the other (whatever parameters you want to choose). Contemplating 10 % differences simply doesn´t make sense in this context.

 

[Moondog55]

I'm going to have an attempt at a Ri-pole using those old MTX subwoofers, just one pertinent query if I may?
Is power handling of a Ri-pole improved over the driver in free-air ind if so by how much??
It will be a rough test box to start with so I suspect exactness of construction will be absent, will + / - 10^ be too much variation for evaluationpurposes??

Regards
Ted

 

[Rudolf]

I'm going to have an attempt at a Ri-pole using those old MTX subwoofers, just one pertinent query if I may?

Post #106

Is power handling of a Ri-pole improved over the driver in free-air ind if so by how much??
It will be a rough test box to start with so I suspect exactness of construction will be absent, will + / - 10^ be too much variation for evaluationpurposes??

How do you define power handling?
Fs will be reduced (but it is of no use for your MTX), around Fs efficiency will be slightly raised compared to an H frame of same depth. Otherwise efficiency will be same or less than the H frame. Power handling will hardly improve - excursion will limit the useable power almost the same as in free air.

 

[Moondog55]

Thanx Rudolf, thats what I was wondering as in free air it goes to X-max very quickly and factory spec 9.4mm is actually X-max plus 15%, so in reallity it's only 8mm.
It is going to be a cheap enough experiment and the drivers have no value on the S/H market.
It will take me a few days but I'm intrigued by the possibiliiues of these types of speakers.
If I make a mistake it will not cost me too much.
Thank-you for your help and input
Regards and
Merry Christmas to all Christians
Ted

 

[Moondog55]

OK , first thing I notice, how simple a ripole is to build if you have a router and a circle cutting guide.
I just bought 4 Chipboard panels 450mm * 450mm * 16mm thick.
Sounds big until you cut a 390mm circle from the centre.
I am going to go now and assemble the bits and post a first subjective report, with happy snaps.
I intend to layer the chipboard with a second layer of MDF, which will give me a total thickness of 28mm.
Now all I have to do is find my camera.

 

[Moondog55]

Tight fit, have to buy different material for sides.

http://farm4.static.flickr.com/3103/3116825049_c2906cd918.jpg?v=0

http://farm4.static.flickr.com/3109/3117652820_c2c6ec1d39.jpg?v=0

http://farm4.static.flickr.com/3109/3117652820_c2c6ec1d39.jpg?v=0

http://farm4.static.flickr.com/3271/3117653816_38df27164c.jpg?v=0

I need to get thinner timber the 32mm dressed pine won't fit.
Other option is 19mmDAR and a second layer of 12mm MDF

 

[Ciu]

About Speakers coupling

Hello !

If I would try a ripole with a Monacor SPH300TC , need 4 speakers for a stereo system :
This speaker has 2 coils, each 8 Ohms
So, I would like to connect each speaker with 2 coils //, that gives 4 Ohms, but in series with the same speaker in front of
The total would give 2 speakers 4 Ohms each, in series to make 8 Ohms
Is there any problem to do that, what would be the global Qts seen by the amplifier, is there any problem with phase ?

Thanks
R.C.

 

[chrisb03]

Here's a photo of what I have done so far, the left one is sanded. It's for a pair of 12inch Peerless SLS 830699. Not sure how I am going to do the centre chamber yet. Was thinking about using something else (non mdf).