Home audio loudspeaker - 8"/10"/15" Coaxials crossover at 1000Hz

[krivium]

Hi Swara,
Ok your room is about 50m3 volume so from my experience i would not use too big drivers.
My take on this ( which is from experience and my guts feeling nothing i can point to research or science related background) is if you ONLY RELY on mains's drivers for sub don't use more than 12".

I think there is a point at which you start to 'overpower' your room with too much energy in the bass with 'big' drivers. And you face the issue of room placement, which may be perfect for the medium high but excite room mode too much (for example). If sub is on the mains's box there is not much that can done in that case ( except going multi sub).

With a modular approach to box this can be minimised.
An other approach is to go MTM or TMM as it is a crude ( and simplistic) approach to a distributed bass. For this you can downsize driver size ( eg: 2x12" is more or less equal to 1x18" membrane area, 2x10" to 1x15", etc,etc,...).

This is one approach which may be convenient... or not! And i expect to be corrected (or not) in my view of this.

About filtering ok you run a computer as source.
Here again there is multiple options here is one: invest in a multiple output good quality soundcard ( or a combo multiple digital output card + multiple D/A converters) and use a software for filter duties.

Something dedicated as Accourate or similar soft for filter and keep your already known player.
Or go JRiver which could integrate player and treatments in a single software. And use Rephase to make your filter profile which are then used to process your drivers 's way.

This way you can use amps tailored to drivers and overcome efficiency difference ( something like low watt high quality class A amp for mid/high and classD monster power for low as example). Once in multiamp dsp, efficiency differences become moot imho ( not totally but much less an issue).

And if you are interested in FIR filters and a bit of 'dsp room treatments' this is still an option.

[Qts]

I think there is not too big drivers. I think it is where room modes are compared to frequency response of the speakers. If they are low enough, where response is going down, they are less harmful.

[gedlee]

Originally Posted by swara

T Where can I buy a oblate spheroid waveguide?

I am not up on the current marketplace, so I don;t know.

Originally Posted by swara

I was more concerned about the phase than a slightly wavy frequency response.

I would think that the opposite would be true.

[gedlee]

Originally Posted by krivium

Hi Swara,
Ok your room is about 50m3 volume so from my experience i would not use too big drivers.
My take on this ( which is from experience and my guts feeling nothing i can point to research or science related background) is if you ONLY RELY on mains's drivers for sub don't use more than 12".

I think there is a point at which you start to 'overpower' your room with too much energy in the bass with 'big' drivers.

I don't see that opinion as very valid. The size of the source does not dictate the amount of LF energy put into the room. Size does determine how low in frequency one can do that and, for my money, bigger is better even in a small room. My HT is a pretty small room and I have 4 15s and 2 12s. three are subs and three 15s are in the mains. That's a lot of very big drivers in a small room and it yields excellent bass with lots of headroom. I think that bigger is always better if you have the room for it.

Originally Posted by Qts

I think there is not too big drivers. I think it is where room modes are compared to frequency response of the speakers. If they are low enough, where response is going down, they are less harmful.

Think of it this way. The room modes will never be "low enough" to not cause problems, except in big rooms. So the LF solution has to deal with this problem. In the modal region, the room dominates the situation, which means that the speakers response is a secondary issue. Using multiple subs and LF EQ is, IMO, the only universal way to deal with the LF mode situation.

[Qts]

My comment was only for now and then heard thing, too big speakers to small room.


I think like you wrote.

[multitask]

directivity is better the larger the baffle/cone, so in theory larger is better in small rooms. but 50 square meters is not small by my measure. wish i had an american style home

[krivium]

Sorry Qts, i don't get your second sentence in post #32.

About coaxials i agree higher diameter have lower control on directivity and this is 'better' than smaller one ( i already stated this in my first post).

My comment was about Sub/ low way in a three way configuration, not a case of 2way coax.

Earl, i was sure we were going to not agree on this. It is difficult to explain this clearly in english as is ( it is a foreign language for me) so i will need some time to formulate my observation about that but i'll do in following post.

For now the thing i can tell you easily and for sure: i live with a 'big' ( more medium sized to me but related to today's standard 100liters is 'big') three ways with 15" ( 38hz to 750hz, 5" mid up to 4,5khz, 1" tweeter) for nearly 25 years now and they followed all my journey in very different place : from student flat of 20m2 to my now main room which is almost 200m3 - 50m2 floor plan with sloped ceiling up to 4meters a bit leaky relative to bass, more in line with US standard room for this part of spectre.

There is no competition: this is the first time i'm not struggling about low end for them. All my previous places had issue with bass and mode with them. This was not the case with my other monitors which have ( had for the ones i don't belong anymore) smaller diameter drivers ( within same bandwidth of around 40hz and i listen with calibrated levels which follow K-20 but instead the 85db reference level this ranged from 75 to 82 dbspl in the different rooms i had).

Multitask: 50m3 NOT 50m2. Swara told 5m x 4m x 2,7m: around 50m3. This the volume which matter in my view.

[Brett]

Originally Posted by mayhem13

\my method has always been 3 way and NOT have the cone move at all to keep the intended waveguide properties as stable as possible, and that's using an 8" coax crossed in the 250hz range steep filter.

I've been doing this for about 20 years. I did it first with Tannoys of all sizes and every time I mentioned it to a Tannoy diehard, you could actually hear the pearl clutching even from overseas.

My current surrounds are Faital 8HX200 and AE TD15X, DSP active with xovers at about 300 and 1k7 IIRC, both LR24. I'd be happy with them as mains. The Faitals measured pretty close to the datasheets too.

[ttan98]

Originally Posted by Brett

I've been doing this for about 20 years. I did it first with Tannoys of all sizes and every time I mentioned it to a Tannoy diehard, you could actually hear the pearl clutching even from overseas.

My current surrounds are Faital 8HX200 and AE TD15X, DSP active with xovers at about 300 and 1k7 IIRC, both LR24. I'd be happy with them as mains. The Faitals measured pretty close to the datasheets too.

How do find the quality of the your Faital 8HX200, the sound and the high freq horn and the and the mid-range driver? Does it come with the High freq. horn when you buy it or you buy separately?

[Brett]

Originally Posted by ttan98

How do find the quality of the your Faital 8HX200, the sound and the high freq horn and the and the mid-range driver? Does it come with the High freq. horn when you buy it or you buy separately?

It's excellent. No external horn, it's like a Tannoy. If you mean the CD, it comes with it; phenolic sort of diaphragm.