so looking at the second one (forward and up), and at around 20-15L, will a sealed be best or have i any more choices?
would having a FR125 be worth the extra cost rather than having a WR125 on top?
would having a FR125 be worth the extra cost rather than having a WR125 on top?
Probably not. Other options could include an MLTL or reflex loaded enclosure, but with an upward-firing driver, they could be a little tricky to get working optimally (I won't go into why here, or we'll be here all night -suffice it to say, it's to do with harmonic resonances, and how they are activated). If you're using a sub, then sealed is the best bet, unless you fancy an aperiodic enclosure of course, which can have a few advantages.
so how can i model an aperiodic enclosure? can i do it in WinISD?
would having a FR125 be worth the extra cost rather than having a WR125 on top?
would having a FR125 be worth the extra cost rather than having a WR125 on top?
No. And, IMO, no, though if you've got the cash available, it won't exactly do any harm either. Law of diminishing returns really.
Aperiodics are a pain to model. You can do it in Martin's MathCad worksheets (to an extent). And there's only one paper on the theory and design methods available that I know of (thank's Dave!), written by Ted Jordan 50 years ago. Useful, but not very readable! They're one of the more interesting sides to speaker design that remains fairly obscure, which is a pity.
Probably the best way forward is to come up with a good, sealed box alignment. Then add the vent to that. I suspect it's difficult for one to be too small -all that should happen is the driver / enclosure will behave as if the vent wasn't there, and as you started out with a good sealed alignment in the first place, this isn't a problem. Likewise, I doubt you could really have too large a vent to cause yourself major problems -just add more damping inside, or behind it to restrict the air-flow some more. Scan Speak have some ready-made ones available -only problem of course is that you're much more limited in your tuning options. If they're too small, you could add another. But if they're too large, you can't add more damping to the venty, you'd have to open up the enclosure and add some behind it, which is a bit of a palarver. To be fair, they do look quite swish though, as aperiodic vents go! Omega use a couple I believe on the back of their big A8 standmount. Better really just to do as Dave and others suggest -cut a slot in the cabinet, and play around with the damping yourself. Cheaper too.
Best
Scott
Aperiodics are a pain to model. You can do it in Martin's MathCad worksheets (to an extent). And there's only one paper on the theory and design methods available that I know of (thank's Dave!), written by Ted Jordan 50 years ago. Useful, but not very readable! They're one of the more interesting sides to speaker design that remains fairly obscure, which is a pity.
Probably the best way forward is to come up with a good, sealed box alignment. Then add the vent to that. I suspect it's difficult for one to be too small -all that should happen is the driver / enclosure will behave as if the vent wasn't there, and as you started out with a good sealed alignment in the first place, this isn't a problem. Likewise, I doubt you could really have too large a vent to cause yourself major problems -just add more damping inside, or behind it to restrict the air-flow some more. Scan Speak have some ready-made ones available -only problem of course is that you're much more limited in your tuning options. If they're too small, you could add another. But if they're too large, you can't add more damping to the venty, you'd have to open up the enclosure and add some behind it, which is a bit of a palarver. To be fair, they do look quite swish though, as aperiodic vents go! Omega use a couple I believe on the back of their big A8 standmount. Better really just to do as Dave and others suggest -cut a slot in the cabinet, and play around with the damping yourself. Cheaper too.
Best
Scott
i think i would just go for a WR125 if it does not have a big advantage.
i can get 2 WR's for £83 from germany or 2 FR's for £110 from UK (both inc Del)
so when you add foam bungs into the ports on speakers, does that make them almost aperiodic.
so in summary, what are the advantages of aperiodic over sealed?
thanks
i can get 2 WR's for £83 from germany or 2 FR's for £110 from UK (both inc Del)
so when you add foam bungs into the ports on speakers, does that make them almost aperiodic.
so in summary, what are the advantages of aperiodic over sealed?
thanks
Good prices -where from? I may have to indulge myself.
Yes, it does, though it's not a good idea to design them from that angle.
What advantages? Well firstly, they make a driver behave as if they were mounted in a sealed box typically 20% larger than is actually the case, when properly designed and implemented. They also significantly reduce the big impedence peak that sealed boxes present to the amplifier, meaning it doesn't have to work as hard. Downside is that they are rather more tweaky -you need to spend much longer fooling around with them to optimise their performance.
Yes, it does, though it's not a good idea to design them from that angle.
What advantages? Well firstly, they make a driver behave as if they were mounted in a sealed box typically 20% larger than is actually the case, when properly designed and implemented. They also significantly reduce the big impedence peak that sealed boxes present to the amplifier, meaning it doesn't have to work as hard. Downside is that they are rather more tweaky -you need to spend much longer fooling around with them to optimise their performance.
I built a set of aperiodic boxes using the Nothcreek design. The FR's don't bottom out as much when really pushed. Nice over all sound. They are referenced here: http://www.diyaudio.com/forums/showthread.php?s=&threadid=59762&perpage=10&highlight=&pagenumber=24
Scottmoose said:
Hi Scott,
regarding the actual conversion rate Euro/GBP you pay 80 GBP for a pair of WR125 or 100 GBP for a pair of FR125 including shipment from Germany to UK (VAT and tax included).
Regards
Thorsten
regarding the aperiodic boxes, whats the point of the smaller chamber?
should the enclosure be a multiple of the VAS?
yeah, my calculations were from http://www.boxen-baustelle.de/
what about these for ideas?
should the enclosure be a multiple of the VAS?
yeah, my calculations were from http://www.boxen-baustelle.de/
what about these for ideas?
An externally hosted image should be here but it was not working when we last tested it.
Aha. Cheers guys. I might be able to stretch to those. (Need something to compensate for not being able to afford the 206ES-Rs. Blasted car... mutter, growl, sledge-hammer etc. £450 it cost me, and it still needs a new calalytic convereter. Another £175. I'm starting to wonder if a horse might be a cheaper option.)
What's the point of the smaller chamber? Well, I'd call that a side benefit rather than an objective (unless you have a limit on the size enclosure you can use, in which case, you get the performance of a 20% larger enclosure without it being quite so large). The principle benefits are in reducing the big impedence spike spike of a regular sealed box, so you end up with reduced distortion, an easier load for the amplifier, and also better LF quality. It'll also assist in clobbering any unwanted extra internal pressures.
I like the first one. Of everything though, I'd just stick with a basic rectilinear box with golden ratios, bipole if you have the space, an upward-firing driver if you haven't. Simpler to construct. The fancy shapes will probably have more benefits to a vented or TL type enclosure -I suspect they'd be minimal for a sealed / aperiodic design.
It doesn't have to be a multiple of the Vas (which doubles if you have two drivers BTW). Basically, there is only one rule with them as Dave outlines on his site: the bigger the enclosure, the closer the box Qts approaches to the free air Qt). That's it. Driver position can cause notches in the response due to the build-up of quarter-wavelength standing waves, but that's not news -it applies to any enclosure to varying extents.
What's the point of the smaller chamber? Well, I'd call that a side benefit rather than an objective (unless you have a limit on the size enclosure you can use, in which case, you get the performance of a 20% larger enclosure without it being quite so large). The principle benefits are in reducing the big impedence spike spike of a regular sealed box, so you end up with reduced distortion, an easier load for the amplifier, and also better LF quality. It'll also assist in clobbering any unwanted extra internal pressures.
I like the first one. Of everything though, I'd just stick with a basic rectilinear box with golden ratios, bipole if you have the space, an upward-firing driver if you haven't. Simpler to construct. The fancy shapes will probably have more benefits to a vented or TL type enclosure -I suspect they'd be minimal for a sealed / aperiodic design.
It doesn't have to be a multiple of the Vas (which doubles if you have two drivers BTW). Basically, there is only one rule with them as Dave outlines on his site: the bigger the enclosure, the closer the box Qts approaches to the free air Qt). That's it. Driver position can cause notches in the response due to the build-up of quarter-wavelength standing waves, but that's not news -it applies to any enclosure to varying extents.
ok, so is the smaller chamber sealed from the larger one?
so i should just go for a sealed 20-25L rectangular cabinet then play around afterwards with the aperiodic vent?
so i should just go for a sealed 20-25L rectangular cabinet then play around afterwards with the aperiodic vent?
to change tack slightly im looking to build a home theatre. Im think of using http://homepage.mac.com/tlinespeakers/FAL/box-plans/bipolar-miniOnken-v08.gif for my L & R.
To get a better idea without listening to the aboveand allowing me to compare volume to what i currently have what sort of RMS power could you feed into these without any distorsion?
To get a better idea without listening to the aboveand allowing me to compare volume to what i currently have what sort of RMS power could you feed into these without any distorsion?
Hi
please allow me to interfere.
If you have measurement equipment or if you are a experienced LS designer with very well trained ears, the upfiring version could be a really interesting subject.
If not, I think that can easily get out of control and you might better go for a real bipole or 1.5 way frontfiring in your widebaffle - still enought tweaking involved to not be boring.
For the upfiring version, I personaly would try to get an opinoin first, from one of the bipole geeks, like Dave (planet10) or Greg (GM) or Jim Griffin...
...but that just my humble opinion.
best, LC
please allow me to interfere.
If you have measurement equipment or if you are a experienced LS designer with very well trained ears, the upfiring version could be a really interesting subject.
If not, I think that can easily get out of control and you might better go for a real bipole or 1.5 way frontfiring in your widebaffle - still enought tweaking involved to not be boring.
For the upfiring version, I personaly would try to get an opinoin first, from one of the bipole geeks, like Dave (planet10) or Greg (GM) or Jim Griffin...
...but that just my humble opinion.
best, LC
hi, thanks,
i only have around 1 ft from the wall for a thin and deep enclosure but i have 2ft for a wide and shallow enclosure.
so i do not think i have enough room for a normal bipole, which is why i looked at the upfiring option,
whats the 1.5 way idea?
i only have around 1 ft from the wall for a thin and deep enclosure but i have 2ft for a wide and shallow enclosure.
so i do not think i have enough room for a normal bipole, which is why i looked at the upfiring option,
whats the 1.5 way idea?
From the acoustical viewpoint I would say that for a bipolar design the two drivers need to be on opposite sides (front and back) of the cabinet. Otherwise the drivers produce a skewed radiation pattern which may lead to distortion of the sound.
The 1.5 way designs places both drivers on the front of the box. You attenuate one driver via a series inductor at the BSC corner frequency so that you can effectively blend the speakers' radiation at this 4 pi to 2 pi response transition. This works just fine for BSC as you have a 6 dB per octave transition.
The 1.5 way designs places both drivers on the front of the box. You attenuate one driver via a series inductor at the BSC corner frequency so that you can effectively blend the speakers' radiation at this 4 pi to 2 pi response transition. This works just fine for BSC as you have a 6 dB per octave transition.
lovechild said:
LC - Bert Doppenberg published plans a few years ago for a quite successful little bipole TQWP in which the "rear/second" driver was mounted on a 45degree panel.
http://www.t-linespeakers.org/FALL/bd-pipes.html
This was in fact my introduction to fullrange drivers, and Dave & I played around with several combinations with and without front tweeters.
While regardless of the driver (RS40-1197, Fostex 103, vintage Fosters, etc, etc,) there will be a limit to the low end extension and ultimate SPL, they are quite a musical little creature, and in fact with a powered sub have made for several happy HT owners.
"The 1.5 way designs places both drivers on the front of the box. You attenuate one driver via a series inductor at the BSC corner frequency so that you can effectively blend the speakers' radiation at this 4 pi to 2 pi response transition. This works just fine for BSC as you have a 6 dB per octave transition."
could you put that into laymans terms please 🙂
is this what you mean, would having a wide baffle be better than the thin baffle (if they were the same volume)
could you put that into laymans terms please 🙂
is this what you mean, would having a wide baffle be better than the thin baffle (if they were the same volume)
An externally hosted image should be here but it was not working when we last tested it.
just as a crazy idea, how about 1 Fr125s and two large 4Ohm woofers in an open baffle 1ft x 2.5ft?
i like the look of these... http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=295-376
🙂 🙂 🙂 🙂
i like the look of these... http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=295-376
🙂 🙂 🙂 🙂
An externally hosted image should be here but it was not working when we last tested it.
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