First time OB builder

[Silent Screamer]

I currently have the crossover to the 10" at ~500Hz, but it is seriously lacking bass because of the low 88.5dB efficiency (compared to the 95dB Raal and 93dB mids in parallel).

I notice the 15's you have there are ~100dB mark which should give the bottom end some oomph. Should I use 1 or 2 15" per side? Do you find the single enough for bass heavy music?

Would I gain another 3dB by separate amps on the 4ohm drivers or remain at 93?

 

[studiotech]

I currently have the crossover to the 10" at ~500Hz, but it is seriously lacking bass because of the low 88.5dB efficiency.

I notice the 15's you have there are ~100dB mark which should give the bottom end some oomph. Should I use 1 or 2 15" per side? Do you find the single enough for bass heavy music?

I run a set of sealed Rythmik Servo 15" to augment the B&C 15" below 60Hz, so I'm not actually sure how far you can push them. They will certainly need quite a boost the lower you want to run them, but I think a solid 40Hz might be possible. I like true full-range sound, so OB bass wasn't going to cut it for me.

When I was running the AE Dipole 15, they were not enough for me with bass heavy music at loud volumes.

 

[Silent Screamer]

Ok thanks that is definitely provides food for thought...

I basically have 4 channels to play with per side. I was thinking of perhaps making the OB bass swappable with separate subs for movies, but you are using them in conjunction.

So I could the RAAL tweeter, a pair of 12MUs (which ever config), something like the 15" your using, and a sealed or vented sub per side.

But if I am going with a separate sub do I really need to go 15" for the woofers?

 

[studiotech]

Ok thanks that is definitely provides food for thought...

I basically have 4 channels to play with per side. I was thinking of perhaps making the OB bass swappable with separate subs for movies, but you are using them in conjunction.

So I could the RAAL tweeter, a pair of 12MUs (which ever config), something like the 15" your using, and a sealed or vented sub per side.

But if I am going with a separate sub do I really need to go 15" for the woofers?

Yeah, not many 15" I'd like to use up to 500 if I could help it, unless you want to spring for an AE Lambda TD15! Those are amazing drivers. Maybe a nice 12" would do the job. I really like the B&C because it measures well and has a small neo magnet and a nice, open aerodynamic frame. See some good measurements of larger woofer here:

https://sites.google.com/site/drivervault/driver-measurements

I would certainly use a proper sub under 50-60hz unless you want to follow Stig's lead and have massive OB subs.

 

[Silent Screamer]

Just looking for full pictures of StigErik's system now...

Well I don't really need to cross over as high as 500 merely doing that to try get some more life out of the 10".

Take a look at the 12MU graph and tell me where you would cross over from the 12MU's to the 15" please.

 

[studiotech]

Stig's thread:

http://www.diyaudio.com/forums/multi-way/142015-my-open-baffle-dipole-beyma-tpl-150-a.html

Hope you have some time to spare! It's quite a journey and totally worth following every step! Epic...

You need to see how the 12MU measure without a baffle. You might get away with 350hz, but hard to tell without distortion plots while EQ'd to play that low OB. I run my B&C 15" up to 300hz no problem.

 

[Silent Screamer]

Thanks for that Greg, just found that same link while looking through the "Ultimate OB Gallery", seems in the world of OB, big is beautiful

 

[picowallspeaker]

You need to think about the wavelengths involved. He's looking at crossing at 2k which is a wavelength of 6.75".

As far as woofer isolation, in my application the naked driver "scaffolding" is mounted to the u-frame, but the wire suspending the drivers hangs from rubber grommets. That plus the "swinging" action of the cable ensures little to no vibration transfer from the woofer to the upper drivers. They pass the touch test at least when the woofer is doing 40hz, which is as scientific as I'm willing to get here.

yes , I made a dipole last winter and readily disassembled it after one week .
The swinging and corruption from vibrations induced by the woofer wasn't
acceptable ( maybe because the mids and tw's were cheap stamped steel & plastic ) and I didn't like them on the floor , so I didn't investigate further
on how to 'put the patch' .
I recognize that suspending the speakers is the only way to eliminate mutual
interference . That applies not only to OB ...

 

[Silent Screamer]

Was just looking to see if the Raal could be converted to a dipole and low and behold they already make one that way...

Madisound Speaker Store

 

[Silent Screamer]

OK I'm probably pushing a visit from the men with the white suit that does up at the back, but what do you reckon to a couple of these?

$1000 a piece plus freight, but damn that response curve looks nice. One in each of the mains and another 2 in H boxes?

 

[Silent Screamer]

Yeah, not many 15" I'd like to use up to 500 if I could help it, unless you want to spring for an AE Lambda TD15! Those are amazing drivers. Maybe a nice 12" would do the job. I really like the B&C because it measures well and has a small neo magnet and a nice, open aerodynamic frame. See some good measurements of larger woofer here:

https://sites.google.com/site/drivervault/driver-measurements

I would certainly use a proper sub under 50-60hz unless you want to follow Stig's lead and have massive OB subs.

The AE aren't that dear, and the do seem to be designed for OB. Unfortunately I can't find a frequency response for them. Anyone used them that can put a good word in for them?

 

[studiotech]

See my nearfield measurements in this thread:

HTGuide Forum - Dipole 15 here now too

flat to 20Hz with no EQ. Of course this is up close before dipole rolloff takes effect, but even measured at my listening distance, I only needed minimal EQ to stay flat.

 

[Silent Screamer]

Can't look at those things without thinking there is a silver vibrator stuck to the front of it

They certainly are open on the back and ideal for dipole. Was thinking about the height of them if I was to get two for each side they would be 30-36" high just for woofer.

Would a separate tweeter / mids / mid woofers along side work?

 

[studiotech]

What about going wide with the woofers. Side by side both low. You could make an H-frame and then place the mid/tweet baffle on top as a separate piece. Or just use one, live with it for a while and if you need more bass, make some nice subs.

Greg

 

[picowallspeaker]

OK I'm probably pushing a visit from the men with the white suit that does up at the back

Be nice with them

 

[Silent Screamer]

Greg I did consider side by side but that would make each speaker 36+” wide… Plus even with them low I’m not sure I would still get all of the drivers above them.
After my tuning session last night with the RAAL crossover roughly 2.5k and the 2 x 10” crossed over at 1k, I felt the midrange was still a little thin vocally and really needs a pair of proper mid woofers to bridge the gap between the 15” or 18” woofers.
So just doing a speaker count that would be 2 x 120mm (12MUs), 1 x RAAL tweeter, 2 x 8” Drivers (unknown as yet) and the woofers. That is going to make for a high and wide speaker.
Figuring if I could stack both woofers into one H frame standing up, and run a separate frame holding the other 5 drivers, it would make it not so wide and not so tall.
Hoping I can get away without subs but would add as required. Just an idea open to suggestions…

Picowall I will try not to bite them as they strap me up

 

[Silent Screamer]

Might need those guys with the white coats on standby… Call me crazy but I could have sworn that I can hear more coloration of the 12MU paper driver than I can with the Revelators in the Cremonas (which should be far worse).
Is it possible because of the cleanness of the active x-over and RAAL tweter that my ears are now picking up what they didn’t hear before? Kind of cant see the forest for the tress…
Listening to them I feel like I now need a poly or ceramic mid to match the RAALs, something that is equally crisp.

 

[Beau]

Hmmm, like Accutons... Kidding.
In all seriousness you dont really need twin mids if you are going with twin 8 inch woofers.
The Nao note is a good example of this.
If you restrict its passband from say 600hz up it will cope just fine.

 

[Silent Screamer]

Probably don't but the twins are for distortion reasons. I keep thinking about the Accutons but then keep talking myself out of it.
Basically if I use the Accuton mids, I would also need to purchase something similar for the 8” and then I need to replicate that all around the room.. Lots and lots of money…
Whereas if I used something like the Audio Technology drivers that are poly, they might be more inclined to blend better with the 10 paper 12MUs I already have, and I could use them up in the rears.
Also thinking about buying the RAAL dipoles to replace the 140-15D I have, and use the current RAALs in a centre or rear speakers.

 

[studiotech]

With all of this experimentation(which is great btw), you really need to treat yourself to at least the Dayton Omnimic setup. It really helps take the guess work out of all this and helps confirm that you are hearing things correctly. Best way to train your ears is to listen to various songs for a while, see what you think stands out of is a little weak, take a sweep and see if you can find anything that matches what you think you are hearing.

Of course those 12mu running completely naked are going to sound more colored than the Revelators in a good box. Without proper dipole EQ, they don't stand a chance. Slow down on the crazy driver purchases, really sort out what you've got there on hand and then move forward. Only way to do that is to SEE what you're getting. Then adjust xover, phase and EQ to get a reasonably flat response and now audition the result. Tweak to taste from there. Just having the best drivers in the world does not ensure success. Patience young Padawan you must have.