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Multi-Way Conventional loudspeakers with crossovers

Need Help: Designing 12" Tannoy + 15" Woof
Need Help: Designing 12" Tannoy + 15" Woof
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Old 29th October 2019, 10:01 PM   #11
planet10 is offline planet10  Canada
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Need Help: Designing 12" Tannoy + 15" Woof
18g will likely have way too high a DCR. I never use electrilytics.

But you also have to deal with the rise in the impedance at resonance. COmpensating for that likely means many components to deal with that so that the XO has a chance of working.

dave
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Old 30th October 2019, 06:19 AM   #12
KrautNotRice is offline KrautNotRice  United States
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Quote:
Originally Posted by planet10 View Post
18g will likely have way too high a DCR. I never use electrilytics.

But you also have to deal with the rise in the impedance at resonance. COmpensating for that likely means many components to deal with that so that the XO has a chance of working.

dave
Gotcha.
The 18ga 10.0 mh inductor has a DCR of 2 Ohms, the 15 ga version only 1.2 Ohms. But it's triple the price, putting me dangerously close to buying subwoofer plate amps to power each 15" woofer. A decent 250 - 300 Watt plate amp is around $140 + depending on sales, sometimes even lower.

Regarding the passive low-pass around 200 hz, would it be a simple 2nd order?
Can the 12" Tannoy driver be high-passed simply by virtue of being mounted in a small sealed enclosure? (I'm sure there's a technical term for that)
What kind of crossover would be needed for the drivers to be phase coherent to avoid a suck out of bass near the xo point?
The impedance correction you mention, could it be as simple as a parallel resistor, or does it have to be complicated?
If I did cross the woofer over passively, I would use an electrolytic cap as it's not in the signal path and only on a woofer playing 200 hz and down. I can't afford to be an idealist there.

If building passives costs anywhere near half as much as a pair of plate amps, it's a no brainer to go active. The plate amps would just have to have high level inputs as to not complicate setup all too much, so the only inconvenience at that point would be one power cord per tower speaker.
Thanks for your input!
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Old 30th October 2019, 06:23 AM   #13
KrautNotRice is offline KrautNotRice  United States
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I used to have a pair of NHT SuperTwo towers, and one of the things that bothered me very much is that there was a 15 db suck out of bass near the xo point ( 115 hz or so ) between the down firing sub and the front firing mid. Certain bass notes would just be missing out of the program, I couldn't stand it. I want to avoid that.
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Old 30th October 2019, 06:43 AM   #14
planet10 is offline planet10  Canada
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Need Help: Designing 12" Tannoy + 15" Woof
Quote:
Originally Posted by KrautNotRice View Post
Gotcha.
The 18ga 10.0 mh inductor has a DCR of 2 Ohms, the 15 ga version only 1.2 Ohms.
Still probably too high.

Quote:
...putting me dangerously close to buying subwoofer plate amps to power each 15" woofer.
Now you are starting to get it :^)

Quote:
Regarding the passive low-pass around 200 hz, would it be a simple 2nd order?
Can the 12" Tannoy driver be high-passed simply by virtue of being mounted in a small sealed enclosure?
With a subwoofer amp that is pretty much how you have to do it. XO will be wherever a Q=0.707 sealed box has its F(-3).

Quote:
The impedance correction you mention, could it be as simple as a parallel resistor, or does it have to be complicated?
It will probably be an RCL shunting the driver.

Quote:
I would use an electrolytic cap as it's not in the signal path
i donít think that anything in the XO is not in the signal path. And certainly the big cap on the Tannoy will be directly in series.

and only on a woofer playing 200 hz and down. I can't afford to be an idealist there.

Quote:
If building passives costs anywhere near half as much as a pair of plate amps, it's a no brainer to go active. The plate amps would just have to have high level inputs as to not complicate setup all too much
It likely is. Especially since you are not likely to get a passive right on the 1st pass.

You donít need a high level input (althou if you have a set of variable level pre-amp outs line level is preferable). The subs i have in my living room most often get hooked up with speaker wires coming off the mains terminals.

dave
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Old 30th October 2019, 07:00 AM   #15
Zvu is offline Zvu  Serbia
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Quote:
Originally Posted by KrautNotRice View Post
I used to have a pair of NHT SuperTwo towers, and one of the things that bothered me very much is that there was a 15 db suck out of bass near the xo point ( 115 hz or so ) between the down firing sub and the front firing mid. Certain bass notes would just be missing out of the program, I couldn't stand it. I want to avoid that.
You'd have to be certain that it wasn't the room or some reflection interference rather than loudspeaker. Have you measured any other loudspeaker at that same speaker and mic position ?
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Old 30th October 2019, 07:04 AM   #16
KrautNotRice is offline KrautNotRice  United States
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You'd have to be certain that it wasn't the room rather than loudspeaker. Have you measured any other loudspeaker at that same speaker and mic position ?
Yes I did lots of testing and measuring at the time, and ended up removing the passive crossover and bi-amped the towers via electronic crossover (passive crossover only between mid & tweet)
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Old 30th October 2019, 07:07 AM   #17
KrautNotRice is offline KrautNotRice  United States
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Originally Posted by planet10 View Post
Now you are starting to get it :^)
dave
Well it is settled then, either plate amps for the woofers, or build small monitors with these drivers.
In the tower with helper woofer version, how do I calculate whether or not the Tannoy driver needs to be high-passed, or if it's sufficient that it would be mounted in a small sealed enclosure? You mentioned a series cap for the Tannoy, are you saying it would have to be high-passed?
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Old 30th October 2019, 07:10 AM   #18
Zvu is offline Zvu  Serbia
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I'll see what i can do about assessment of crossover components needed to cross woofer around 150Hz as soon as i get to my computer (in an hour or two). Drivers are pistonic down low so it should be quite close to actual values needed.

Why wouldn't you want to mount he woofer below the dual-concentric ? Aesthetics or some other reason ?
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Last edited by Zvu; 30th October 2019 at 07:15 AM.
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Old 30th October 2019, 07:14 AM   #19
KrautNotRice is offline KrautNotRice  United States
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Quote:
Originally Posted by Zvu View Post
I'll see what i can do about assessment of crossover components needed to cross woofer around 150Hz as soon as i get to my computer (in an hour or two).

Why wouldn't you want to mount he woofer below the dual-concentric ? Esthetics or some other reason ?
Thanks! It's for aesthetics, I like the clean design. Also I was thinking it might help with voices and other midrange out of the woofer not being heard if the woofer is firing down.
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Old 30th October 2019, 07:14 AM   #20
Zvu is offline Zvu  Serbia
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The point is that you will not need full baffle step since there will be lots of boundary reinforcement. That means that you can get by with a woofer that doesn't have to be 4-6dB more sensitive than midrange.
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