Hi all!
I've been reading the forum for some time, and now I'm finally attempting to build my first loudspeaker using crossovers. I really need some help... I think I may have finished my design, and I'd be most grateful for your input!
I settled on a 2.5 way tower speaker, with 2 Tang-Band W4-657SB mid / woofers and a Neo3 PDR tweeter each, time aligned.
Anyway, I must have logged 24 hours or more in LSPCad 6 by now. I have designed 2 crossovers. One of them gives me the flattest frequency response (Third order on the tweeter; second order on the woofer with an added RC shunt circuit); the other one has a pronounced dip (Third order on the tweeter; second order on the woofer). - but it stays above 4 Ohms all the time.
I'll be using the speaker with a Rotel separate amp and a tube amp with a 4 Ohm tap. But I wonder if they can survive a dip to 2 Ohms like the one the "flattest" design has.
I really don't know if the "flattest" design has a good overall impedance, or if the depression on the 4 Ohm min. design will be audible. I can build any of the two crossovers... and I need your help!
This first post has the graph for the "flattest" design...
I've been reading the forum for some time, and now I'm finally attempting to build my first loudspeaker using crossovers. I really need some help... I think I may have finished my design, and I'd be most grateful for your input!
I settled on a 2.5 way tower speaker, with 2 Tang-Band W4-657SB mid / woofers and a Neo3 PDR tweeter each, time aligned.
Anyway, I must have logged 24 hours or more in LSPCad 6 by now. I have designed 2 crossovers. One of them gives me the flattest frequency response (Third order on the tweeter; second order on the woofer with an added RC shunt circuit); the other one has a pronounced dip (Third order on the tweeter; second order on the woofer). - but it stays above 4 Ohms all the time.
I'll be using the speaker with a Rotel separate amp and a tube amp with a 4 Ohm tap. But I wonder if they can survive a dip to 2 Ohms like the one the "flattest" design has.
I really don't know if the "flattest" design has a good overall impedance, or if the depression on the 4 Ohm min. design will be audible. I can build any of the two crossovers... and I need your help!
This first post has the graph for the "flattest" design...
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Hi Al, thanks for your answer!
I'm not worried at all about the peak on the impedance curve, but the sub-4 Ohm impedance from 500 Hz to 2000 Hz! It reaches it's minimum point at around 1,200 Hz, with some 2.1 Ohms of impedance.
I'd love to build the "Flattest" crossover, but I'm worried about that dip on the impedance.
On my first post, look at the first graph... that's the one that worries me (the frequency response looks fine to me).
I'm not worried at all about the peak on the impedance curve, but the sub-4 Ohm impedance from 500 Hz to 2000 Hz! It reaches it's minimum point at around 1,200 Hz, with some 2.1 Ohms of impedance.
I'd love to build the "Flattest" crossover, but I'm worried about that dip on the impedance.
On my first post, look at the first graph... that's the one that worries me (the frequency response looks fine to me).
pinkmouse said:
That's good to know
I'll be using a Rotel RB-1070 with them, or a Margules Audio ACRH-1 (the designer told me it would drive a pair of MartinLogans without issues, so I'm not worried too much).
The thing is, I'd love to try the speakers with a DIY tube amp I have, which is a clone of the Leak TL-12+'s. It has a 4 Ohm tap, but I'm not sure it can survive the dip. I think it could be a non-issue, since it's rather high in frequency, but since this is my first effort, I'm not really sure.
Thank you very much for your help. Hopefully, I won't have any issues with impedance, and I can build the crossover this weekend! I'm happy.
I personally would be doing everything to avoid the 2 ohm drop. Do you have a schematic of your crossover? You may need to get more creative in your topology.
Also, is the low frequency performance into half or full space (i.e do you have baffle step compensation?).
What kind of response are you after ? Fourth order Linkwitz Riley?
Also, is the low frequency performance into half or full space (i.e do you have baffle step compensation?).
What kind of response are you after ? Fourth order Linkwitz Riley?
Hello all,
Thank you very much for your input.
Ap, the drivers are 8 Ohm (the woofers) and the tweeter is 4 Ohms.
David, thanks. I arrived at the topology using Vance Dickason's book and trial and error. I took into consideration the baffle step compensation by doing some nearfield measurements of the woofer, simulating the BSC directly in JustMLS, and creating a BSC circuit in LSPCad. I'm after a 4th Order Acoustic Linkwitz-Riley response.
Fung, yes! I never noticed how low the crossover slope was. I don't know why, but I thought it was closer to 2 KHz than it really is. I agree - I don't think the tweeter would sound very good at such a low frequency.
After taking into consideration all your kind comments, I arrived at a new topology. I think that while trying to get rid of some extra energy at around 1.5 KHz from the woofers I was dropping the impedance far too much. Hopefully, this one is a lot better than the other (no 2 Ohm dip, impedance doesn't drop below 4 Ohms, crossover frequency at 2.3 KHz).
Thank you very much for your input.
Ap, the drivers are 8 Ohm (the woofers) and the tweeter is 4 Ohms.
David, thanks. I arrived at the topology using Vance Dickason's book and trial and error. I took into consideration the baffle step compensation by doing some nearfield measurements of the woofer, simulating the BSC directly in JustMLS, and creating a BSC circuit in LSPCad. I'm after a 4th Order Acoustic Linkwitz-Riley response.
Fung, yes! I never noticed how low the crossover slope was. I don't know why, but I thought it was closer to 2 KHz than it really is. I agree - I don't think the tweeter would sound very good at such a low frequency.
After taking into consideration all your kind comments, I arrived at a new topology. I think that while trying to get rid of some extra energy at around 1.5 KHz from the woofers I was dropping the impedance far too much. Hopefully, this one is a lot better than the other (no 2 Ohm dip, impedance doesn't drop below 4 Ohms, crossover frequency at 2.3 KHz).
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