three way with woofer as sub

[kingfisher]

need help with HIVI M1 + powered sub. I am building this tweeter mid-woofer sub-woofer combination and would like opinions before I purchase the sub-amp. I had built the M1 KIT back in 1997 from parts-express. I sold them some time back but had a chance to buy another pair needing work. The neww project will use all of the parts from the M1 Kit, I thought that before I build the cabinet, I should plan on incorporating a sub-woofer in each speaker and build two large speakers boxes. My plan is to keep the baffle face narrow (F5 + RT1-C) and to have the sub-woofer(D10.8) fire from the side of the box. The woofer will be powered with an amplifier which has a phase switch. My question to the forum is: do any of you forsee a phase problem? and if so, how should I aproach the fix? Will the (0 to 180 degree phase switch) be adiquate?
Kingfisher

[Charles Darwin]

I don't see how phase problems could arise in this case.
Unless you wire the woofer wrongly of course…

[tinitus]

Originally Posted by Charles Darwin

I don't see how phase problems could arise in this case.

but it does, whenever you try to make 2 drivers work together
no matter if you use xo components or not
you still have two slopes to match, with a mutual xo point
slopes variation makes a difference

crossing a sub very low may make it easier
but still better if you can make get the roll off slopes to match
and remember, thats on the acoustic side, on speaker output

[kingfisher]

Thank you Charles and tinitus,... I will keep this in mind. tinitus could you elaborate further on the xo slope opinion? If I could crasp an understanding of this I may choose another approach better suited. Are you talking in terms of 1st order, 2nd order ect...? The Amp I would suspect would take care of the crossover to match. However the amp does not have a veriable phase control, so phase angle may be an issue at some frequencies due to lacation and declination (ie, direction).

[blue934]

king fisher , you have a PM

david

[tinitus]

Originally Posted by kingfisher

tinitus could you elaborate further on the xo slope opinion?

1. If I could crasp an understanding of this I may choose another approach better suited.
Are you talking in terms of 1st order, 2nd order ect...?
2. The Amp I would suspect would take care of the crossover to match.
3. However the amp does not have a veriable phase control, so phase angle may be an issue at some frequencies due to lacation and declination (ie, direction).

first you need to know that what matters are the acoustic slopes
acoustic slopes differs from calculated electrical
why
simply put, because there are no ideal speaker
you might say that they have a "behaviour of their own"
many many variables inside the design interacts with each other

variable phase control is just a simple rough substitute
better to have variable slopes
why
because fixed selectable slopes are only electrical
what you get on the acoustic side may end very different, and likely will
why
because its a fits all solution
to work properly, amp and woofer would be matched and adjusted together
and even then, a designed package is usually still made from one size fits all componts
its not just a matter of getting a certain roll off slope on woofer
it should still match midrange slope
and even what happens between mid and tweeter matters
its a complete system

subwoofer rolloff may work ok with fixed slopes
why
because xo point is usually very low
woofer is "attacked" far from where it behaves non linear, simply put
so, whats the problem then
midrange roll off slope
its the one that may not match
and the one you may have to deal with

today I wouldnt dream of using other than digital dsp
not that its "fool proof", because most issues are still the same
but at least it gives a chance to get it right
thou, the mean thing is that the many option you have with dsp also opens the door to a possible hell

Im not saying that ordinary subamps wont work
its just reminder that it doesnt work as pr auto, like seem to expect in quote #2 I expect amp to care of that
it may work well, and satisfying
but still good to think about what actually happens when connecting all these different components

but surely also a matter of expectations, and goals

[Simon]

Hi Kingfisher,
Am i right in thinking the M1 is a bass reflex design ?
If so are you intending to keep this arrangement or go sealed ?
I think it will make a difference "phase-wise" at the point at which you crosseover to the sub.

[klinko16]

I used 2 x d10.8 as a Separate subwoofer, with the 500W amp from part express. right now, i am using the parasound 7100 processor, and it does the subwoofer crossover in the digital domain, so this takes care of phase problems the best. my own experience with using the d10.8 as a true sub is astonishing and unbelieveably good.
i basically copied the design from:
Subwoofers
I am a real believer now, in having a separate subwoofer, in ADDITION to using full range left and right. my current setup is with the Selah audio 3 way dipole,
with bass driver x 2 per side in a sealed cab, scan speak mid bass and tweeter in d'Apolito configuration, but dipole. the f3 for the selah is about 42hz. the 10.8 transmission line subwoofer takes over from there, and makes it really sound like you are in the actual recording studio or performance venue. the sewer pipe is completely stuffed with wool, and the result is extremely tight fast bass, extremely profound deep bass, quite astonishing. since you have not yet built your project, i thought i should offer my experience, and encourage you to look into this project.