Need help designing speakers

[planet10]

Originally Posted by Bare

Why? with a 'decent' quality 12" woofer would you even want, let alone Need a Sub?

Because, in most rooms, it takes multiple (sub)woofers located in much different places than where the mains are optimally placed to get smooth, well distributed bass.

dave

[Moondog55]

Assuming a box width of 450mm to suit the 10 inch woofer i would suggest a simple 2.5Way speaker.
This is a first project and needs to be kept reasonably simple and as cheap as possible. having said that the Marshal Leach XO is as good a starting place as any.
Putting in a .5 woofer at the F3 or F6 point for baffle step losses and using the small Vifa mid in a sealed box would be my starting point.
F3 point is 255Hz in a 450mm box

[system7]

The Marshall Leach twoway design is what you'd call a genuine bookshelf speaker. The smallish simple (0.42mH) inductance on the bass coil means it needs to be positioned close to a wall for good bass performance. The plus is that you gain efficiency by doing this, because you have less midrange rolloff on the 6.5" (0.6mH) bass cone. The downside is you let through a lot of bass cone breakup which sounds harsh to the trained ear.

The circuit below will get rid of a lot of that cone breakup noise and have more bafflestep, so might sound best on a stand. The Tweeter Zobel will work with most 0.05mH tweeters. The 4.7 ohm "select on test" tweeter attenuator will match levels well enough on a crossover around 3.5kHz. Perhaps 3.3 ohms will be optimal, but see how it goes. Bright treble is quite annoying.

If you want a three-way design, I'd really not want to be involved. Way too complex.

[Bare]

Originally Posted by planet10

Because, in most rooms, it takes multiple (sub)woofers located in much different places than where the mains are optimally placed to get smooth, well distributed bass.

dave

OK.. Just like in a Cineplex??
In truth though I've Never Ever actually experienced that particular problem. And here I thought Subs were a sop to a poor setup. Silly Me.

[planet10]

Originally Posted by Bare

OK.. Just like in a Cineplex??

Bad example.

dave

[Moondog55]

Originally Posted by system7

If you want a three-way design, I'd really not want to be involved. Way too complex.

I tend to agree with this for beginners, however using point 5 woofers is technically easy

[Keswick]

Thanks for all your input guys, I am reading all this. Adrian.

[sreten]

Originally Posted by wintermute

Hi Sreten, I'm curious because I see you post about no BSC designs
often, but I want to know exactly what you mean by it.

1. there is no obvious BSC compensation circuitry in the crossover
or
2. you can tell by looking at the crossover that does not have
any compensation at all and the speaker will have thin bass.

Tony.

Hi,

I can't see the difference. Basically any design with the tweeter
level set to the bass/mids sensitivity has no BSC, may be on
purpose (not good as at least some is needed), or ignored.

It does depend the bass/mid drivers response also.

What I usually mean is the design description implies either BSC
is simply ignored in the design process, or that its purposefully
ignored or limited to maintain the speakers sensitivity figure.

Fair enough if you've got tone controls and want to use them.

rgds, sreten.

[sreten]

Originally Posted by Keswick

Thanks for all your input guys, I am reading all this. Adrian.

Hi,

Given your list of drivers, to use them all in a speaker would require
design of a very large 4 ohm 3.5 way, 12", 10", 6.5", 1" horn.
(the 12" and 10" specifications don't really tally with each other.)

However the 6.5" is designed for for a good 2 way with decent bass,
and not really as a high SPL midbass driver, don't know the tweeter.

rgds, sreten.

[wintermute]

fair enough, and I just realised how to tell without simulating or doing any calculations, I checked the published specs of the drivers, along with his comment about the padding being about 4db. There is 3db sensitivity difference between the tweeter and the woofer so at most there could be 1db of compensation (by rolling off the bass a bit earlier, and cutting the tweeter an extra db, which isn't really going to do very much).

Tony.