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Multi-Way Conventional loudspeakers with crossovers

Some advice for a noobie
Some advice for a noobie
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Old 5th December 2018, 05:26 AM   #11
head_unit is offline head_unit  United States
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Join Date: Feb 2004
Location: Los Angeles
Quote:
Originally Posted by DenDog View Post
Hi! I am new to the forum and the DIY audio world so I was hoping some of you guys could help me out a bit .
Welcome! And yes, we will be glad to "help" you with a welter of contradictory opinions + a wild surfeit of mind-overloading information

Quote:
Originally Posted by DenDog View Post
...I would like my speaker to be as small as possible without major performance loss.
Google "Hoffman's Iron Law" to see why this is not possible, due to physics. Or maybe you already get this per your EBP reference.

Ported speakers have more output, with less excursion of the main driver, near the port frequency. Below that frequency, the port becomes a short (say that 10 times fast!) and unloads the main driver, whose excursion can go nuts. The port tuning is a consequence of the air volume in the port (a mass) versus the air volume inside the box (a spring). Thus, tiny enclosures cannot be tuned really low except by a tiny port...which cannot flow enough air to be meaningful. Passive radiators can *somewhat* get around this if you can load enough mass to tune them low, but there's a limit to that. To a first approximation, a passive radiator is a ported system. The delay of the air starting to move through the port means the time response of a ported system is not as good as a sealed design, though how noticeable vastly depends on a lot of factors. In my experience, I don't want any response bump at all. That could sound "more full" but could "sound like sh$t."

Sealed systems by contrast offer somewhat less bass, with more controlled excursion and tighter sound.

For an outdoor small speaker, I really wouldn't worry about baffle step response and so on, unless you just want to which is cool.

As for the crossover, mmm, do you have any way to actually measure the drivers? Without actual data things can work, but maybe not optimally. Once upon a time, back during the last Ice Age, I calculated a crossover out of a book and painstakingly built the whole thing...then ended up with a giant cancellation, since the actual response magnitude and phase didn't match the assumptions. And no, I don't trust data from different manufacturers, since they always use somewhat or even radically different equipment and setups.
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Old 5th December 2018, 06:40 AM   #12
hollowboy is offline hollowboy  Australia
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Join Date: Jul 2007
Location: 'straya
Quote:
Originally Posted by Galu View Post
You say you have already bought the Dayton drivers so will need to concentrate on getting the best performance out of them.
Whoops, I missed that the OP had already made the purchase! My bad.
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Old 5th December 2018, 03:00 PM   #13
Galu is offline Galu  Scotland
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Join Date: Apr 2018
@ hollowboy:

@ DenDog: After reading your last post, I suspect that you simply hoped to have your decision to use PRs endorsed by forum members.

If you require further assistance with regard to your chosen design please feel free to ask.
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Old 6th December 2018, 02:32 PM   #14
DenDog is offline DenDog  Netherlands
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Join Date: Nov 2018
This is indeed mind-overloading information. But I love it!
I really want to learn more about this and know how to build an optimal system.
I HAVE SO MANY QUESTIONS

@head_unit: how much would I need to spend to get a cheap measuring mic? And by that I mean something that I can use for future projects but not for the insane audiophile measurements.
Maybe you have some suggestions?

@Galu: That was indeed what I was hoping for, but I guess it's not as easy as it seems!

@hollowboy: I don't really understand what just happened here:
"The tuning you get (from stuffing this 6" into a small box) will give about 1.7dB of midbass boost (around 150Hz), which will help give the impression of fuller bass. Indoors, that might sound a bit boomy. Outdoors, I think it would be a good thing."

What do you guys mean by "midbass bass boost" and "upper bass boost" and how would I select drivers for a small boombox like mine?


I intend to also make some speakers for when I move into my new room. So these drivers are probably more suitable for a project in that environment I guess?

Maybe I will buy some new drivers for this project then..
From what I have just learned (please correct me if I'm wrong) I am looking for a driver that:
Has a low F3 so I get decent bass from a small driver.
high sensitivity to get enough sound from low power.
which of course brings us back to head_unit's mention of the Hoffman law where if I want a small enclosure this is not possible.

So I guess I will have to compare a lot of them and make the trade offs!


For the new driver selection, should I go for a build plan to get me started on making a crossover and stuff?
Or do you guys say just go for it and it will be fine haha
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Old 6th December 2018, 03:36 PM   #15
Galu is offline Galu  Scotland
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Join Date: Apr 2018
Put these books on your Christmas list. A bit more basic knowledge can't hurt!

The Loudspeaker Design Cookbook: Amazon.co.uk: Vance Dickason: 9780962419171: Books

Designing, Building, and Testing Your Own Speaker System with Projects: Amazon.co.uk: David Weems: 9780070694293: Books
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Old 6th December 2018, 03:54 PM   #16
Galu is offline Galu  Scotland
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Join Date: Apr 2018
Quote:
Originally Posted by DenDog View Post
What do you guys mean by "midbass bass boost" and "upper bass boost" and how would I select drivers for a small boombox like mine?
The box shapes the low frequency response of the loudspeaker.

Scroll down in this link to find out about the effect of Qtc.

speaker basics
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