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Multi-Way Conventional loudspeakers with crossovers

Fast, fun, Inexpensive OB project
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Old 15th July 2014, 08:23 PM   #1101
John Busch is offline John Busch  United States
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Default Bass issues

Part of the design compromise that keeps the Manzanita simple, both in terms of layout and component count, is the use of the large woofer series inductor. It not only compensates the woofers rising response in an OB set up, it also provides part of the 2nd order low pass function. However, while accomplish the above.... it also has an interaction with the effective woofer (system) Q adding about 3-5 db of boost in the 46-56 Hz region. The exact amount and frequency is influenced by the baffle width, wing depth, the actual initial Q of the woofer, baffle distance from side and rear walls and so on. One can use a smaller inductor with shunt resistor, but.... when that was tried the bass extension was some what compromised... and in my personal estimation was not a good trade off. And you have to have about 30 -50 watts of dissipation on the shunt resistor, which is a bit expensive. Usually speaker placement relative to side and rear walls can dampen down the boost to less than 3 db and return the low end balance. This is a very flat outcome especially compared to what is realized with most closed box speaker systems.
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Old 15th August 2014, 01:14 PM   #1102
donovas is offline donovas  South Korea
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hello, i play with different midrange to manzanita.

i have tangbane w4-1320 bamboo. i shunt it by 10ohm resistor across terminal, pad resistor raised to 8ohm, trap value 2.4mh and across resistor varying with a pot.

sound very good, mid and high more good against vifa. tangband less dispersion against vifa, so less unified sound. (maybe cone shape, too? vifa cone just look like peerless cone, so they sound 'same') had phase issue before pad resistor, i could hear unnatural combination. pad resistor solves it.

but

upper bass bad with tangband. tangband 4", vifa 3.5", but vifa more dynamite sound. stronger bass. this because qts? how solve? less highpass cap for tangband? (tangband 75hz fs, vifa 125hz?)

eventually i want use alpair 6p. how prepare for this?

please teach. thank yous john.
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Old 15th August 2014, 04:03 PM   #1103
donovas is offline donovas  South Korea
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hello, i make l-pad for 12.5ohm, adjust from then. sound better > best.

why no shunt resistor for vifa, could i ask?

i am strong belief this shunt method work ok to alpair 6p with.

i use this calculator.
http://www.sengpielaudio.com/calculator-Lpad.htm

first see vifa got 4db attenuation.
then think i need 10db attenuation because tangband 1320 6db bigger.

then i think for tangband Z is 12.5 ohm because with vifa 12.5ohm?

last part ok?

this sound i receive best so far to present. no more vifa 'pheesh' high treble.

Last edited by donovas; 15th August 2014 at 04:25 PM.
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Old 2nd September 2014, 01:29 AM   #1104
leo vendramini is offline leo vendramini  Australia
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Default A cheap alternative ?

Hi,all I just checked out the specs.on the Visation WS 25E-8 and am wondering if it could be used as a cheap substitute for the Peerless in a smaller sized room? C/O tweaking would probably be fairly basic.Any opinions would be handy as this driver is easily available in Australia.
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Old 2nd September 2014, 06:54 PM   #1105
Pano is offline Pano  United States
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Fast, fun, Inexpensive OB project
I don't think a single 10" per side would work very well. Maybe 2 per side.
The 25E-8 us also not high effeciency. X-max is OK at +/- 6mm. The Qts is very high, which will make it sound fat and loose. That can actually work on OB.

But if you use it, you are charting your own course. You may end up spending a lot of time and money on the crossover. Let's see what John thinks.
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Old 3rd September 2014, 03:37 AM   #1106
John Busch is offline John Busch  United States
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Default Visaton 10

I agree with Pano, two of the WE-25-8 wired in parallel (in phase as a 4 ohm load) would be a good way to go. Yes, with the high QTS, a single 10 could work, but would have limited output, especially below about 50 Hz. And you would have to tame the 15 db rise shown on the frequency response graph. That would require some trap work. The trap would also be require with both single and dual woofer formats.


A single unit would also be about 3 db, maybe more less efficient. So that would require some additional adjustment on the H.F. driver pad, which would also effect the high pass cross over capacitor value.

It comes down to how much work you are willing to do to make the different design, well, work....
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Old 3rd September 2014, 04:15 AM   #1107
leo vendramini is offline leo vendramini  Australia
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Default Visation alternative

Thanks to both of you.Can you please suggest the components I should use to tame the 15db rise you noticed?Please forgive me for being a pain in the backside,`cause I simply don`t know.My intuition has told me the Visation is the way to go in my small room.Thanks for creating this fabulous thread.
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Old 16th September 2014, 03:05 AM   #1108
oculi is offline oculi  Australia
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Just finished reading the thread, very interesting! will have to make a pair if I get the space and time to do it.

I have two possibly dumb, but quick questions:

1: given the high cost of the large inductors, would it be worth using an active crossover instead? is there "magic" in the passive crossover that wouldn't be in the active?

2: would there be any downside in radiusing/rounding the edges of the baffle with a router? when I have my hammer in my hand everything looks like a nail, when I have my router in my hand everything looks like use the router on it.
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Old 16th September 2014, 08:32 AM   #1109
peterbrorsson is offline peterbrorsson  Sweden
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@ oculi,
Reading is your friend in the bay)
I'm not Mr Busch;o) but you better invest in a DSP device if you're going active. In the long run cheaper if one doesn't have the knowledge in passive designs.

Peter


Quote:
Originally Posted by John Busch View Post
Part of the design compromise that keeps the Manzanita simple, both in terms of layout and component count, is the use of the large woofer series inductor. It not only compensates the woofers rising response in an OB set up, it also provides part of the 2nd order low pass function. However, while accomplish the above.... it also has an interaction with the effective woofer (system) Q adding about 3-5 db of boost in the 46-56 Hz region. The exact amount and frequency is influenced by the baffle width, wing depth, the actual initial Q of the woofer, baffle distance from side and rear walls and so on. One can use a smaller inductor with shunt resistor, but.... when that was tried the bass extension was some what compromised... and in my personal estimation was not a good trade off. And you have to have about 30 -50 watts of dissipation on the shunt resistor, which is a bit expensive. Usually speaker placement relative to side and rear walls can dampen down the boost to less than 3 db and return the low end balance. This is a very flat outcome especially compared to what is realized with most closed box speaker systems.
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Old 16th September 2014, 11:38 AM   #1110
Juhazi is offline Juhazi  Finland
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Quote:
Originally Posted by peterbrorsson View Post
@ oculi,
Reading is your friend in the bay)
I'm not Mr Busch;o) but you better invest in a DSP device if you're going active. In the long run cheaper if one doesn't have the knowledge in passive designs.

Peter
Very true, a minidsp 2x4 will do! You will need two stereo (power)amplifiers too.
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