TMWW crossover questions

elshout

Member
2006-07-20 11:35 pm
I have some questions I hope someone can answer for a TMWW type of speaker. All drivers are 8 ohms.

I know that when you create a three way crossover for
a Tweeter, Midrange, and a Woofer, if it is a parallel
crossover and all drivers are 8 ohms, that this does
not create a problem as each driver is producing a
different spectrum of the audio range so it still
presents as approximately 8 ohms.

In the Tweeter, Midrange, Woofer, Woofer speakers that I have seen, this is mostly true except for the two
8 ohm woofers in parallel. Just two 8 ohm woofers
wired in parallel become 4 ohms. How does it work in
this type of speaker? Does the complete speaker present as
about 6 ohms overall? Or is it still 8 ohms except for
the lower range?

Also, how would this work if you wanted to bi-wire?
Would you have an 8 ohm top end and a 4 ohm bottom
end?

I hope the questions make sense and I hope someone can
help me understand how these TMWW type of speaker
crossovers work.

If someone needs an example of what I am talking about, look at the Veritas kit at PE: http://www.partsexpress.com/project...as&FTR=veritas&CFID=22892657&CFTOKEN=13628007

Thanks
Scott
 
elshout said:


Just two 8 ohm woofers wired in parallel become 4 ohms. How does it work in
this type of speaker? Does the complete speaker present as
about 6 ohms overall? Or is it still 8 ohms except for
the lower range?


If you look at the specs sheet of a driver it's almost never 8 ohms, that's nominal, but a value under the name of Re.

Sometimes it does not present that value that is taken from the driver but one that is driver(s)+xover that varies in frequency.

elshout said:


Also, how would this work if you wanted to bi-wire?
Would you have an 8 ohm top end and a 4 ohm bottom
end?


No. (depending on the spekers (drivers+xover). I would assume that they are 8 ohms, then bottom end also 8 ohms. But what you said is true. Some 8 ohms speakers present an impedance lower than 6/4 ohms sometimes. You need to have caution.
 

Thawach

Member
2007-12-13 9:48 pm
hi scott


if you use bi-amp that the woofers wired in parallel are 4 ohms.
The top end is 8 ohms.(i suppose that the impedance is not increase)

you don't think about total impedance. it does not work at the same
frequency. but the total frequency may be lower when it work
at the over lap frequency respond because it works at the same
frequency. scott i begin to roll my brain.lol:D


Thawach