Rather than a tower i would like to build a short stout speaker on a low tilted stand for a vintage look. Could I just fold the Pencil 7 length in half or would this mess things up? It would obviously have a wider baffle.
Something like this
Something like this
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Ignoring the shift in baffle characteristics, not realistically I'm afraid given the relatively modest length and large cross section. You'd be better off with a box closer to those dimensions, or a pipe with a smaller CSA that gives more flexibility in the folding.
Thank you for making these plans available. It's my first build so I should learned to walk before running and stick with the pencil 7 dimensions. It's my first time learning the CNC also.
I was under the impression the mass loaded quarter wave length is calculated specific to the driver and thus be a specific length but designs i've seen the lengths vary widely. Am i missing something obvious? I'm planning my my first build.
Examples Nereid Pluvia 7HD RTL, ML Voigt, Frugal horn MK3, storm shadow.
I thought it was calculated at a quarter wavelength of the driver resonance frequency. I think I need to go back to square one on my learning. Do you have any recommendations on where to start? I'll start with one of your plans you've kindly made available to get the ball rolling but i would really like to design my own one day.
I just finished a set of 7HD CGR’s from Dave. The larger sized 13L ones. They are fantastic.
(I’m waiting for better weather before finishing them)
(I’m waiting for better weather before finishing them)
The free smaller 9 litre CGR: https://frugal-phile.com/boxlib/P10free/CGR-dPlu-Ken7HD-0v81-240123.pdf
And here a visualization that illustrates their versatility of this shape if the driver is small enuff.
dave
And here a visualization that illustrates their versatility of this shape if the driver is small enuff.
dave
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Should be good. After you've built them (or anything with a slot port) please consider inserting a cardboard divider or two to make a folded line -- and report back your findings 😉
You do realise those aren't conventional vented boxes? They're resistively vented / partially aperiodic alignments, so sticking internal panels in at random is likely to simply tune them even lower and attenuate their already well-damped output. I'm all in favour of experimenting, but if that's the goal, then generally I'd suggest picking a starting point that gives a shouting chance of it working or offers a degree of extra flexibility -acoustically large alignments are usually best in that sense as you have gain available. In this case, not a great idea as they're already quite tightly defined and controlled (as well as being quite highly refined by Dave), which gives little leeway for lowering tuning via extreme internal modifications.
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OP had first asked if he could "fold the Pencil 7 length in half". I agree with everyone that would be tough to do. Then a 13L not-so-small CGR was suggested. And then a 9L. Whatever OP decided to build, "folding in-half" at no cost ought to be tried, to confirm for himself -- or otherwise "falsify" the presumption it could not possibly work. Who amongst the experts would have thought the 2" Alpair 5.2 in just 3.75L cab could have great bass down near 50hz?
OP can (and probably ought to) test/adjust the CGR's vent spacers; after all, several options were given in the design drawing pdf. It would be a convenient time to L/R compare "spacered vent" vs "unspacered open-vent but folded," cabs.
OP can (and probably ought to) test/adjust the CGR's vent spacers; after all, several options were given in the design drawing pdf. It would be a convenient time to L/R compare "spacered vent" vs "unspacered open-vent but folded," cabs.
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People can certainly adjust vent spacers in the CGRs, although I wouldn't say anybody 'ought' to do anything though, above all given that it requires a rebuild of the enclosure & the options are largely aesthetic (the varying aspect ratio & losses are part of the tuning).
There is no 'presumption' above: if you read what I said again, you'll see that I simply pointed out a fact and made a recommendation that should be useful for somebody who wishes to experiment along those lines. Adding internal baffles (which would require pulling a CGR box apart) in the manner described is likely to lower tuning depending on exactly how it is implemented, and this will reduce gain. That's just basic physics. Since the CGRs already have a damped alignment, this will likely result in a box with little output, which is only going to be ideal if that's your goal. If it isn't, and people want to try this approach, then I'd suggest that they start with a box that has an acoustically large volume to begin with. That will ensure they will have a reasonable amount of gain potential, which will in turn give some tuning flexibility.
As for the 5.2, the volume mentioned is roughly equivalent to B4 with a bit of series R factored in for wire-loop, connections etc., so there is nothing implausible about achieving some output to the low 50Hz regions; as you know, my own preference for a simple compact TL / tapered QW for the 5.2 was Bloodhound, which I designed back in 2015 & is only a little larger, with an Fb of 65Hz & anechoic F10 of roughly 55Hz depending on damping.
There is no 'presumption' above: if you read what I said again, you'll see that I simply pointed out a fact and made a recommendation that should be useful for somebody who wishes to experiment along those lines. Adding internal baffles (which would require pulling a CGR box apart) in the manner described is likely to lower tuning depending on exactly how it is implemented, and this will reduce gain. That's just basic physics. Since the CGRs already have a damped alignment, this will likely result in a box with little output, which is only going to be ideal if that's your goal. If it isn't, and people want to try this approach, then I'd suggest that they start with a box that has an acoustically large volume to begin with. That will ensure they will have a reasonable amount of gain potential, which will in turn give some tuning flexibility.
As for the 5.2, the volume mentioned is roughly equivalent to B4 with a bit of series R factored in for wire-loop, connections etc., so there is nothing implausible about achieving some output to the low 50Hz regions; as you know, my own preference for a simple compact TL / tapered QW for the 5.2 was Bloodhound, which I designed back in 2015 & is only a little larger, with an Fb of 65Hz & anechoic F10 of roughly 55Hz depending on damping.
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But the vents are the same in each. Do note that miniOnkens have very tight tuning. Adding more vent and lossing internal volume is going to dramatically affect a very carefully choosen tuning shape.
dave
You could fold a half miniTower. But it migh be small enuff as is. https://www.diyaudio.com/community/threads/microtower-bipolar-ml-tl-for-chr-70-or-el70.148901/
dave
dave
My 7hd's have arrived!
I'm going for the Pensil for my first build, its quite exciting
🙂
I'm going for the Pensil for my first build, its quite exciting to start my first build. Can i ask what the design principles of the miniOnkens are? Is this a bass reflex?
I'm going for the Pensil for my first build, its quite exciting
🙂
My 7hd's have arrived!
I'm going for the Pensil for my first build, its quite exciting to start my first build. Can i ask what the design principles of the miniOnkens are? Is this a bass reflex?
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