Looking for good bass to 200Hz

[hugobors]

Hello,

I've an open baffle that cover the 200Hz 20Khz frequency range at 96db/1W/8Ohm. So I'm looking for a good bass woofer to go with...
Problem is that I prefer it to be passive, so exit OB woofer because no equalisation.
I prefer close cabinet for transcient response and lit's ess boomy than bass-reflex.

So what's your opinion about having dipole above 200Hz and monopole under 200Hz.

And do you have some opinion on a good closed box from the lower frequencies to 200Hz.
I had the idea to put 4 10" in serie paralel configuration to achieve good bass response, and sensitivity in the 96db range.

Do you have some opinions on this or oder ideas...

Thanks

[Virtalahde]

After lots and lots of thinking, I'm probably going to use Peerless SLS-8's afterall in closed cabinet. I'm gonna use two for some ~90dB sensitivity, in a cabinet of 150 litres or so. Maybe bigger.

SLS-8 (and SLS-10) should give F3 a tad under 50Hz. For 96dB sensitivity, you could use 3 woofer per side. Cabinet for 3 could be about 150 litres minimum (for qtc=0.707), but bigger would be better.

EDIT: The load would be difficult with three woofers though..

[richie00boy]

When you say passive, do you mean you want to restrict yourself to a passive crossover, or just not use EQ?

[Magnetar]

Not sure you can get the Madison 21" woofers where you live - no eq needed

Here is what I did with them on an open baffle

[Rudolf]

Hugo,

with limiting yourself to passive x-overs you are cutting your one leg. And with constricting to monopole bass below 200 Hz you are cutting your other leg. Which leaves you paralyzed. That´s IMHO

I know this is a harsh metapher, but let me explain:

Getting some plate amp with an appropriate LP x-over or a stereo amp with some passive-line-level x-over will give you much more choice in the woofer compartment for a lower price than investing in high efficiency woofers.

And avoiding dipole operation where it works best for you (below 200 Hz) can only be excused if size is a real problem for you. Both simulation and experience have led me to the conclusion, that the cancellation of (some) room modes which you get with that dipole bass is more helpful to the reproduction of music in a room than the "spaciness" which dipole mids can give you.

So it would be a pity if you stop short of a fullfledged dipole system.

Rudolf

[hugobors]

Thanks for all your replies....

When you say passive, do you mean you want to restrict yourself to a passive crossover, or just not use EQ?

My first idea was to be in all passive configuration, thats means passive crossover without EQ.

Not sure you can get the Madison 21" woofers where you live - no eq needed

with limiting yourself to passive x-overs you are cutting your one leg. And with constricting to monopole bass below 200 Hz you are cutting your other leg. Which leaves you paralyzed. That´s IMHO

I know this is a harsh metapher, but let me explain:

Getting some plate amp with an appropriate LP x-over or a stereo amp with some passive-line-level x-over will give you much more choice in the woofer compartment for a lower price than investing in high efficiency woofers.

And avoiding dipole operation where it works best for you (below 200 Hz) can only be excused if size is a real problem for you. Both simulation and experience have led me to the conclusion, that the cancellation of (some) room modes which you get with that dipole bass is more helpful to the reproduction of music in a room than the "spaciness" which dipole mids can give you.

So it would be a pity if you stop short of a fullfledged dipole system.

Yes I know that dipole for bass is very good, and reduce room mode. I've heard the jamo r909 and was very impressed with their bass.
So do you know how they do their EQ? Of course it's in a passive way, that's why I'm interested in... And do you think it's possible to do the same with a lot of 10", a little less 12", less 15", 18", or like magnetar : 21"?
Thanks
Hugues

[Notax]

Originally posted by hugobors

So do you know how they do their EQ? Of course it's in a passive way, that's why I'm interested in... And do you think it's possible to do the same with a lot of 10", a little less 12", less 15", 18", or like magnetar : 21"?
Thanks
Hugues [/B]

Allmost imposible mission, bass dipol and get 96 dB/1W/1m. Look at Jamo 909. Its 2*38 cm basses, probably 95-96 dB each, two in parallel 98-99 dB, but dipol gives -10 dB. So, its 88-89 dB/1W/1m at bass, and probably 1-2 dB less for mid.
In your case, where you need finaly 96 dB, you need 4 bass units for each channel. 101-102 dB per one, +6 dB for four (parallel+series) -10 dB in dipol, its 97-98 dB (minus 1-2 dB over passive x-over). That means 4*18" basses with high efficent.
All this means much much power. Again, active is (allmost) inevitable. For dipol specialy.

If the passive is your final decision, I think you can only go with one 18" (or bigger) 8 Ohm bass with 97-98 dB efficient in bass-reflex enclosure.
Any other way is active or death.

[richie00boy]

Going active would bring far more benefits than the level matching as well.

[Rudolf]

Originally posted by hugobors

So do you know how they do their EQ? Of course it's in a passive way, that's why I'm interested in...

Hugues,
as Notax already explained, you will not get bass dipole action at 96 dB/1W/1m passively. Jamo, I believe, are attenuating those woofers heavily from 40 to 250 Hz (theoretically it should be almost 15 dB, but 10 dB certainly are more realistic). So you need REALLY efficient woofers and REALLY big amps and REALLY expensive fat copper coils to get some bass out of those woofers

And do you think it's possible to do the same with a lot of 10", a little less 12", less 15", 18", or like magnetar: 21"?

If you do not have the means to equalize actively and don´t want to destroy a lot of power, you need drivers with a low Fs and a very high Qts. With Qts=2 and Fs=30 Hz you get a natural 6 db rise from 80 to 30 Hz which could compensate for the dipole loss. But you would have practically no rise from 200 to 80 Hz. So this could only help for a pure subwoofer application.

Rudolf

[hugobors]

Ok, so, to stay in dipole, the best solution is to be in active.

But do you think I can stay with one amp and only do bass boost?

And if yes, one thing I don't like is feedback, so to do an active bass boost, is it possible to do this :

PHP Code:

sign----+-----buff--------------------------------------Sum-------To power amp
        !                                                !
        !----+12dB--------filter low pass 6dB------------!