Fast, fun, Inexpensive OB project

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.
 
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.
 
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.
 
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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.
 
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....
 
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.
 
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.
 
@ oculi,
Reading is your friend in the bay:eek:)
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


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.
 
@ oculi,
Reading is your friend in the bay:eek:)
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

ah thanks, makes sense.

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

yeah the extra amp would at least offset the cost back the other way, I've wanted to do something with active crossovers for ages (not digital though, unless I could use 3 band limited DACs or something from a digital source if that is even feasible) but the more I read the more I realise active crossovers aren't a free lunch either.
 
ah thanks, makes sense.



yeah the extra amp would at least offset the cost back the other way, I've wanted to do something with active crossovers for ages (not digital though, unless I could use 3 band limited DACs or something from a digital source if that is even feasible) but the more I read the more I realise active crossovers aren't a free lunch either.

Well, even DSP is not a free lunch but the possibility to change slopes and equalise in a few moments is great for the learning process. I bought a Sitronic which have six channel, amps, DSP and x-over in one package. Expensive but not so much clutter:eek:)

Peter
 
Hello everyone. Like many others I am very intrigued by the simplicity and cost of this setup. I plan to give a go at it with the GRS 12 subwoofer and the Vifa speaker.

Quick question however- I have limited room, 12x15 sqft (maybe slightly larger) and I watch movies/tv and listen to music in the same room. I know this is not a surround sound stereo, but would it be good to connect to my TV system and watch movies with, along with playing my music? Let me know your thoughts.
 
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There is the option of adding a woofer trap in series with the woofer (coil - cap 15 uf & 0.40 mh in parallel with each other). I have never posted this as it is part of the commercial crossover and it does add to the build cost. This trap does clean the upper end of the woofer band pass.

John

John (or anyone else),

Can you please provide the PE part numbers for the woofer trap components listed above? I'd like to be sure I order the correct parts.

Thanks,

Tom
 
As we where visiting relatives in USA this summer I did picked up the 20mH big inductor and the Vifa's, but I didn't have the guts to get the 15" woofers, the rest of the family also wanted some space in the suitcases.
So I did build me a copy of the Ultra, with a different woofer but otherwise as Manzanita Ultra. The woofers are called Alpha 15-8 from Billebro and with that name I couldn't resist buying them.

Outside on one of the last warm summer days,

An externally hosted image should be here but it was not working when we last tested it.


Below is the response from 1 meter away, I know by now that I should have had the mic on three or four meters away, but the weather is not on my side right now. This is only the woofer without any filter.

An externally hosted image should be here but it was not working when we last tested it.


This is the response curve with the 20mH inductor in place.

An externally hosted image should be here but it was not working when we last tested it.


This is meassured and simulated response curve.

An externally hosted image should be here but it was not working when we last tested it.


As the 20mH inductor is ridiculous expensive in Sweden, I have done some simulations with Xsim and did find that using a 10mH and a 150uF + 10R almost gives the same curves as the 20mH. I have not tested this yet, but I got all the parts needed except time. Blue 20mH, red 10mH.

An externally hosted image should be here but it was not working when we last tested it.


This is the filter, don't mind the highpass part as it is for testing with Vifa TG9-10-04 as this is easier and cheaper to get in Sweden than the original Vifa TC9-18-08, just to keep it true to the subject of this thread (Fast, fun, Inexpensive OB project).

An externally hosted image should be here but it was not working when we last tested it.

I know my speaker isn't a real Manzanita Ultra due to different elements, but a big thanks to John and Pano for sharing this Fast, fun, Inexpensive OB project.

\M
 
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Hello everyone. Like many others I am very intrigued by the simplicity and cost of this setup. I plan to give a go at it with the GRS 12 subwoofer and the Vifa speaker.

Quick question however- I have limited room, 12x15 sqft (maybe slightly larger) and I watch movies/tv and listen to music in the same room. I know this is not a surround sound stereo, but would it be good to connect to my TV system and watch movies with, along with playing my music? Let me know your thoughts.

I have mine in our guest room right now, it is approximately 126 sqft, with lots of furniture, I have tried different distance from the back wall and if they are closer than 1 meter there is no bass at all.
So that is the only thing I can think of, the speaker has to be app. 1 meter away from the back wall otherwise you don't get any bass.

\M
 
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?

I have simulated in Xsim a passive filter made with a 10mH inductor and a 150uF + 10R, blue is 20mH and red is with 10mH. Think it is worth a try, I have the parts but not the time to try it.

An externally hosted image should be here but it was not working when we last tested it.


This is the filter, don't mind the highpass part, just for testing with the parts I got at home.

An externally hosted image should be here but it was not working when we last tested it.


\M