Thanks! Yeah, they can (just barely) squeak by without a sub, but they definitely are better with.
Nice picture I might do a similar thingbut definately with the tweeter.
Anymone suggestion the dimension for such box? Badman, would you have a plan for yours?
Yes, a tweeter is a big plus, these were before I'd made phase plugs and mounted coax supertweeters on them. I wound up with the dayton ND20 FB-4, with a 1.5 ohm series resistor, and 1.5uF cap, but some refinement there would be pretty helpful.
They missed the ball on getting the most "intimate" spacing possible on those.
Really a whole different kettle of fish than the BOFU. Anyone sensitive to an XO in the worst possible place, would likely find a BOFU + TLC a more satisfying musical experience.
I should really revisit the B20 -- i've had 4 sitting in their master carton now for a couple years (and tweeters + phase plug dowels). Jeff's little cube is quite inviting.
dave
>>> I should really revisit the B20...
I'd imagine some form of Fonken would suit them fine among others. The biggest concern is whether or not the mids are 'right' for the listener. If i was better at crossover design i'd try to crossover lower but leaving the B20 alone and adding a tweeter works for me. Other's may require more refinement. Leaving the full range driver to do its thing with little or nothing in its path is like going from whitey tighties to boxers... it just feels better... to me anyway.
Someone asked where the piezo with 8 ohm resister and .47uf cap 'crosses' the B20... piezo is rated at 94db per watt... i know it starts at 6db per octave around 20k... could anyone say where the drivers actually cross? I consider it more of a gradual blend than a crossover.
I'd imagine some form of Fonken would suit them fine among others. The biggest concern is whether or not the mids are 'right' for the listener. If i was better at crossover design i'd try to crossover lower but leaving the B20 alone and adding a tweeter works for me. Other's may require more refinement. Leaving the full range driver to do its thing with little or nothing in its path is like going from whitey tighties to boxers... it just feels better... to me anyway.
Someone asked where the piezo with 8 ohm resister and .47uf cap 'crosses' the B20... piezo is rated at 94db per watt... i know it starts at 6db per octave around 20k... could anyone say where the drivers actually cross? I consider it more of a gradual blend than a crossover.
Nice Idea, a bit too much complication for my project now as it should be for a room just in a cottage. Newer the less the idea is interessting, I would love to hear this combination.
For now I chose the B20 for its price and reputation and I will stay with this choice. So far I builded only one pair of speakers so Im not really experienced, so Im looking to copy a nice project some is willing to share. The project should not be too much complicated...
Its nice to see so much discussion on this topic there are some refresing ideas lying around like for example the coax tweeter
I personally would preffer a simple small box and a easy two way setting. On the other hand its interessting to see where one can go. And may be there is a "ultimate" box for this famous speaker somewhere out there
Maybe i will aperiodic vent one of my B20's in .75cf boxes and see how it compares to the sealed version. I think what badman did looks great and want to hear the results.
Wow, this part has been discontinued... it's an aperiodic vent.
DISCONTINUED Scan Speak 29001 Flow Resistance Vent | Parts-Express.com
Badman's venting would sound different since he tuned to 30hz and the air moves down the back of the box and out the bottom... i may just drill 10 quarter inch holes in the rear of the box and see if i can hear any advantage... does anyone know how to sim aperiodic using WinISD or another app?
Wow, this part has been discontinued... it's an aperiodic vent.
DISCONTINUED Scan Speak 29001 Flow Resistance Vent | Parts-Express.com
Badman's venting would sound different since he tuned to 30hz and the air moves down the back of the box and out the bottom... i may just drill 10 quarter inch holes in the rear of the box and see if i can hear any advantage... does anyone know how to sim aperiodic using WinISD or another app?
Hi, No, horses for courses and your insisting on your course, rgds, sreten.
FWIW your slot ported boxes look absolutely miles out for the driver
parameters, care to share the design process that led you to them ?
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Hi,
I quite agree, but easily fixed if your on the ball, and understand
the design. This is worse, near inexecusable IMO : Scrappy
TBH in context c/o point sensitivity is not a major issue for a girl.
The little cube does not agree with the parameters AFAICT.
rgds, sreten.
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I have not examined badman's box tuning but know from experience these drivers work well enough in sealed boxes similarly sized (but with a bass hump before roll off). The slot may add some kind of deep bass support as well as ease pressure off the driver when it's in a sealed box. I don't expect what he did to alter the overall character of the sound to what i hear and suspect what he's done probably enhances the sound. No matter what the B20 never measures too well anyway. Regardless, they have a pleasant sound for sure that many like. For a wide range driver they offer bass most don't, a recessed midrange that's a nice change from many of the way too forward sounding drivers out there and a subtle treble that's easily improved by a helper tweeter. But i can see why others might not like their somewhat veiled sound. So it's simply a matter of personal taste. There is no way the B20 has as much technology behind it as any B&W but that doesn't mean it won't be preferred by most listeners. The B&Ws i own have too serious a sound. They are dull in comparison to my small sealed B20s with piezo. The B&Ws just don't sound fun even if they are superior in every other way.
Hi,
There may be some sort of fault with the B&W's or your talking chalk
and cheese. Your talking full range with no baffle step compensation,
done before with several loud speakers including Linn. Its different
but not remotely accurate, if you like it fair enough, but most don't.
I'm not knocking the B20, its good for what it is, if that is understood.
That does not mean its best for everyone, it isn't, my point, to be able
to make a sensible choice you need to be able to understand the options.
rgds, sreten.
There may be some sort of fault with the B&W's or your talking chalk
and cheese. Your talking full range with no baffle step compensation,
done before with several loud speakers including Linn. Its different
but not remotely accurate, if you like it fair enough, but most don't.
I'm not knocking the B20, its good for what it is, if that is understood.
That does not mean its best for everyone, it isn't, my point, to be able
to make a sensible choice you need to be able to understand the options.
rgds, sreten.
Using the PE specs, and keeping in mind what the high aspect ratio slot ports do to flatten the response i did some sims.
I started at 100 litres, and kept making the box smaller & smaller, adjusting the tuning to keep a bit of a bump, and a "non-wiggly" 1st derivative of the simmed response.
To my amazement, with just a sacrifice of the F3/F10 i was able to keep going, finaly stopping at 30 litres, at which point i kumped to the 21 litre (3/4 ft^3) of Jeff's box.
Attached are sims of Jeff's box and 21 litre sealed. Knowing what the high aspect ratio ports do, i have to wonder if it is really possible that the vented box is actually flatter than the sealed. Usually i estimate the end response somewhere between the vented sim & the sealed sim... in this case the only significant gain you get with the vented is that the box goes from high pressure to low pressure.
dave
Attachments
With respect to the B&W, i mostly listen to the big ones (at the local hifi emporium). I find them on the boring & lifeless side. The few lessor ones i've heard recently tend towards a strident top end.
The Sonus Faber Ellipas are the only speakers in the shop that have garnered my favour in a long time. Actually monetary outlay fro my whole system cost less than the VAT on those. The SF 6k standmounts on the other hand could eaily be bested by any number of similar size FR boxes we've built (<$500 before finish).
dave
The Sonus Faber Ellipas are the only speakers in the shop that have garnered my favour in a long time. Actually monetary outlay fro my whole system cost less than the VAT on those. The SF 6k standmounts on the other hand could eaily be bested by any number of similar size FR boxes we've built (<$500 before finish).
dave
The only one doing any insisting is you.
No way is it remotely better than $1000 worth of B&W's, that is just silly.
The mid and treble end of most twin cone budget drivers sucks big time,
There's no room for personal preference or interpretation in your statement, a poor attitude to have in a hobby where most things are compromises based upon subjective weighting of a variety of factors. I'm only sharing my design, not insisting that B&Ws or a multiway would be "silly", or "suck big time".
Enough of that. Regarding alignment:
The undersized box provides a high Qtc bump in response, acting as some lightweight bafflestep compensation. It also ensures that the output from the port is significantly damped so that the small port diameter doesn't induce any port noise, while providing a modest amount of extra output in the bottom octave and avoiding unloading at frequencies where the driver is still responding significantly. My alignment allows for relatively high, full range, input without running out of excursion. Further, the characteristics of this rolloff tend to mate well with the boundary reinforcement provided in the typical placement of a small speaker like this. You see similar kinds of alignment in many small speakers, though usually they're tuned quite a bit higher. As you say: horses for courses.
Hello Guys,
I think we are heading a direction that is not what I intendet to go.
Yes the selection of a driver is a matter of personal taste and we could argue on that forewer.
No problem with that, but I would like one day to start the construction
As I dont made anything with this driver before I will have to realie on someones construction.
I think we are heading a direction that is not what I intendet to go.
Yes the selection of a driver is a matter of personal taste and we could argue on that forewer.
No problem with that, but I would like one day to start the construction
As I dont made anything with this driver before I will have to realie on someones construction.
I'd probably go something more like 260 x 290 x 330, spread the dimensions out a little more and buy a small amount more volume, but this should work. The slot vent is a good solution because you can vary the ratios in the vent to distribute any vent resonances, and aim it downward at the back so any higher frequency components will be acoustically suppressed. A traditional front-firing vent tuned so low would be relatively long and have quite a bit of higher frequency components. If you tuned it higher you could get more upper bass (not that 60-80 is so upper, but...) but you'd have the driver unloading higher, so lower power handling.
The box would be getting pretty substantial, and by that point, you'd be better off just building the Pass TL. Further, you'd have horrid comb filtering with the 8"s since they run so high. There are better pure "midwoofs" suitable for MTM designs, the strength of the bofu is that it has a nice mix of bass, listenability, and extension in single driver projects.
I strongly suggest tweaking this driver, too, it can be improved significantly with some modest effort.
http://www.enjoythemusic.com/diy/0310/modifying_ff85ken.htm
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An other could be this:
240x260x750 45litre its basically the solution of fostex for his 206En as bass reflex. But this solution is a bit too tall for me.
btw. how long is the burn in time for the driver?
PS: may be its a silly idea but in general what do you think about such crossovers
Dayton XO2W-3.5K 2-Way Crossover 3,500 Hz | Parts-Express.com
could it be used in this case?
Dayton XO2W-3.5K 2-Way Crossover 3,500 Hz | Parts-Express.com
could it be used in this case?
Those should not be used in any case. Generic crossovers are for the birds. Check out Jeff Bagby's PCD software to model and plan a crossover, if that's what you desire.
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