Best choices for a 3 ways design.

[beppe61]

Dear Sirs,

I would like to try to build a 3 way speaker able to reach down 50 Hz flat.
I have some preliminary doubts anyway:
1) is it better to choose a cone mid or a dom mid?
2) any suggestion of a really great woofer? it should be reproduce the 50 Hz very strongly (read at least 95 dB/2 meters).

Thank you very much indeed.

Kind regards,

beppe61

[Cal Weldon]

Sounds like you may want PA drivers.

What's the budget?

How big do you want your boxes?

Dome mids are not as effeicient as a good PA mid.

What sort of tweeters do you like?

There are so many things to consider that you have to give us some more info before we can really help. Tell us about what you are trying to achieve.

[sdclc126]

Perhaps a 2-way with sub? This is still a 3-way but allows you to use a wide range cone mid to cover the majority of the spectrum and crossover to a low-reaching woofer at a lower point than you could with a dome mid.

I really don't make a big distinction between a 3-way and a 2-way with sub - it's just semantics - you're using three drivers so it's a 3-way. You can have one sub unit per speaker, even built in to the main cabinets so it's all one speaker (though many like to isolate the bass from the rest).

For the efficency you are looking for the PA idea may still be the way to go, but I can't make any specific recommendations.

[Cal Weldon]

Another question: What is your max SPL target?

I agree with CLC about the two way, three way thing, it's really just semantics.

[beppe61]

Dear Mr. Weldon,

please excuse my belated reply but I took time to clear my mind.
I strongly think this discussion will help me very much.
First of all I would like to say that I have thought about a 3 way system beacuse I do not think that is possible to reproduce accurately the range 50-20.000 with just 2 drivers.
Am I wrong ?

>

Originally posted by Cal Weldon
Sounds like you may want PA drivers.

Sorry? What are PA drivers? I really do not know.

> What's the budget?
Let's say 800 USD ? could it be reasonable ?

> How big do you want your boxes?
Not very big indeed. Bookshelf size or tower.
I like a narrow front side. The room is 4,5x6 meters.

> Dome mids are not as effeicient as a good PA mid.
What does it imply?

> What sort of tweeters do you like?
Normal dome tweeters with good dispersion and sound.

> There are so many things to consider that you have to give us some more info before we can really help.
Tell us about what you are trying to achieve.

My general requirements are:
1) let's say frequency response 50-20.000 Hz +-3dB
2) good efficiency and easy load for the amp
3) good soundstage reproduction in the depth dimension

But for instance I do not know if it is better to use a cone or a dome for the midrange.
So the first step would be to select suitable drivers for the project.

Thank you very much again.

Kind regards,

beppe61

[beppe61]

Dear Sir,

thanks for the reply. I am still trying to choose the way to go.

>

Originally posted by sdclc126
Perhaps a 2-way with sub?
This is still a 3-way but allows you to use a wide range cone mid to cover the majority of the spectrum and crossover to a low-reaching woofer at a lower point than you could with a dome mid.

Would it be better?
Is it better to cover the midrange with a cone or with a dome in general ?
And in the case I decided for a 2-way + sub system, which will be the best crossover point?
Besides someone told me that frequencies low down to 80 Hz are still directional.
Under 80 Hz there is no more problem of directionality.
Is it correct?

> I really don't make a big distinction between a 3-way and a 2-way with sub - it's just semantics - you're using three drivers so it's a 3-way.

I agree completely on this point of course. Maybe the best way would be to power separately (biamplification) the woofers(sub) and the satellites.

> You can have one sub unit per speaker, even built in to the main cabinets so it's all one speaker (though many like to isolate the bass from the rest).

For the vibes trasmission ?

> For the efficency you are looking for the PA idea may still be the way to go, but I can't make any specific recommendations.

I have a question: to reproduce accurately the range 50-20.000 Hz do you think that at least 3 ways are needed?
Once I read that to reproduce the full range from 20-20.000 a minimum of 4 drivers are needed (like in the JBL 250Ti for instance).
Is it correct?

Thank you very much again.
Kind regards,

beppe61

[beppe61]

>

Originally posted by Cal Weldon
Another question: What is your max SPL target?

90dB peak (50-20.000 Hz) at 2,5 meter from the speakers.
A good level for movies I think.
Am I wrong? Is it too much?

> I agree with CLC about the two way, three way thing, it's really just semantics.

I agree as well.

Thanks a lot.
Kind regards,

beppe61

[Cal Weldon]

Ok, if you need a narrow speaker then perhaps consider a thin floorstander 2 way with a separate woofer. Maybe a 6.5 woof and a dome tweeter. Do you have a spot to place a woofer box?

If you only need 90 dB then you don't need PA drivers (public address or pro drivers) as they are known for efficiency and toughness, not necessarily SQ.

I would only recommend a dome mid if you have heard it and like it. It would be better in a three way without the separate woofer.

Under approx. 80 hz is non-directional.

I agree that if you have a separate woofer you should have a plate amp to power it. As CLC said, you can have the woofers and amp in the same cabinet as the rest. I have two sets like that, one with a dome mid. The picture is a 4 way and you can see the front and back. Maybe this is the way for you also. You can't make the exact speaker as I have used old and discontinued parts for these, but you can still do it with new if the idea appeals to you. It is really two cabinets in one. It's approximately 10" (25 cm) wide by 12" deep (30cm) by 44" high (112cm)

It can be done for $800USD

I also noticed I have repeated a lot of what CLC said, oops.

Cal

[Curmudgeon]

More questions. Is it primarily for music or home theater? If music, what kind? I agree with the above posters that it does not sound as if you need special drivers for what you're after.

I would suggest that you look at kits; that helps get around the crossover design issue. In the US, Madisound speakers would be a good website to visit, and you could get a feel for cost and availability. Do ou have the tools and ability to build your own cabinets? They are also available as kits. And for a strong 50 Hz, I would go a little larger, to a good 8 inch; and actually if it is used for music I would suggest setting 40 Hz as the lower limit.

It can be done with either a three way or a two way; I prefer three ways, with the mid crossing over at no more than 150 Hz, and the tweeter at 3kHz or so, which puts a real burden on the midrange, but makes woofer and tweeter choices a bit easier. And since most of the signal is in the midrange, it is a good place to put more money relatively. But there are MANY different approaches that work.

[beppe61]

Dear Mr. Weldon,

my sincere congratulations for your excellent work. Very nice speakers indeed !

>

Originally posted by Cal Weldon
Ok, if you need a narrow speaker then perhaps consider a thin floorstander 2 way with a separate woofer. Maybe a 6.5 woof and a dome tweeter.
Do you have a spot to place a woofer box?

I would prefer the one box solution anyway.
Your example is a 4 ways if I am not wrong.
So you think that 4 drivers are needed to reproduce the 50-20.000 range ?


> If you only need 90 dB then you don't need PA drivers (public address or pro drivers) as they are known for efficiency and toughness, not necessarily SQ.

Now I understand. Yes, 90 db are enough in my room.

> I would only recommend a dome mid if you have heard it and like it.
It would be better in a three way without the separate woofer.

No I was only asking if a dome would be better than a cone.

> Under approx. 80 hz is non-directional.
Very important information. Thank you so much.

> I agree that if you have a separate woofer you should have a plate amp to power it. As CLC said, you can have the woofers and amp in the same cabinet as the rest.
I have two sets like that, one with a dome mid. The picture is a 4 way and you can see the front and back. Maybe this is the way for you also.

I would prefer to limit the number of drivers to the minimum, that should be 3 if I understand correctly.

> You can't make the exact speaker as I have used old and discontinued parts for these, but you can still do it with new if the idea appeals to you. It is really two cabinets in one.
It's approximately 10" (25 cm) wide by 12" deep (30cm) by 44" high (112cm)
It can be done for $800USD
I also noticed I have repeated a lot of what CLC said, oops.
Cal

Dear Mr. Cal,

thank you very much for your extremely kind and useful support.
With your help I am clarifying my ideas.
Thank you so much.

Kind regards,

beppe