Well this gets into what I don't know about theory.
The biggest I'd want this rascal to be for build is 36 in high by
16 in or so wide and fairly shallow-- 6 in or less.
The idea of driver offset in an MLTL was also given by GM.
He says that if the box gets shorter, the driver goes higher up the
cabinet. I'd like to maintain the MLTL 1/3 down positioning.
Perhaps my test box is just inappropriate but it's what I have.
Those measures are above at 23 3/4 x 4 3/4d x 10 3/8 w internal.
I have winISD. Maybe you can describe a bit on how to use it.
I should review all my materials. From using winISD what it gives is
volume and port length for BR as I recall.
The biggest I'd want this rascal to be for build is 36 in high by
16 in or so wide and fairly shallow-- 6 in or less.
The idea of driver offset in an MLTL was also given by GM.
He says that if the box gets shorter, the driver goes higher up the
cabinet. I'd like to maintain the MLTL 1/3 down positioning.
Perhaps my test box is just inappropriate but it's what I have.
Those measures are above at 23 3/4 x 4 3/4d x 10 3/8 w internal.
I have winISD. Maybe you can describe a bit on how to use it.
I should review all my materials. From using winISD what it gives is
volume and port length for BR as I recall.
165 & 166 aren't ideal for mass loaded straight lines -not without some form of correction at any rate. The former can be used in a mass-loaded horn like Martin's Project 2, but it really does prefer the non mass-loaded horn varieties as it doesn't have a great deal of linear excursion. 167 is my choice of the 6 1/2in Fostex units.
I've attached the pdf of my MLTL plans (DIY use only -have to mention it here because it doesn't on the file unfortunately). It's actually using as narrow a baffle as possible as I needed a floorstander that behaved ~like a compact standmount at the time. But you can mount the driver on the wide face easily enough.
I've attached the pdf of my MLTL plans (DIY use only -have to mention it here because it doesn't on the file unfortunately). It's actually using as narrow a baffle as possible as I needed a floorstander that behaved ~like a compact standmount at the time. But you can mount the driver on the wide face easily enough.
getting closer
Thanks for the pdf. I am now confident enough to place an order
and start experimenting.
Two things:
How would the port area translate into a round bottom exit tube?
Why the double baffle on the front? And the driver placed on the
interior baffle? No wave guide is showing in the design.
Scottmoose said:
Thanks for the pdf. I am now confident enough to place an order
and start experimenting.
Two things:
How would the port area translate into a round bottom exit tube?
Why the double baffle on the front? And the driver placed on the
interior baffle? No wave guide is showing in the design.
Right -the driver is surface mounted. There's no real advantage to flush mounting these units BTW, although you can if you feel so disposed -it won't do any harm. Why a doubled baffle = you can never have too stiff a driver mounting.
You can use a cylindrical port tube if you like. 4in diameter x 5in long as close as possible to the bottom. Actually, that's what I'd do if I were to build this particular box again: finishing slot vents is a pain in the neck.
You can use a cylindrical port tube if you like. 4in diameter x 5in long as close as possible to the bottom. Actually, that's what I'd do if I were to build this particular box again: finishing slot vents is a pain in the neck.
Bob Brines increases the thickness of the top and the baffle in his MLTLs (1.5" thick with 1.0" for sides, bottom and back - see http://www.geocities.com/rbrines1/).
You might consider purchasing the plans for Bob's FT-1600 MkII, an MLTL for the FE167E. It will save you the trouble of fine tuning a cab and developing the BSC. At $25 the plans save you considerable time and heartache.
You might consider purchasing the plans for Bob's FT-1600 MkII, an MLTL for the FE167E. It will save you the trouble of fine tuning a cab and developing the BSC. At $25 the plans save you considerable time and heartache.
holdent said:
Heartache might be excessive. This is my winter project like the Harvey or BIB before it. My trial box has a grille and stand all set already even though considerably smaller than the ideal.
I am noting from Scottmoose the manner of stuffing for the sample build
though what I've done in the past is start with nothing in there to see what happens.
One thing I neglected to do was chamfer the cutout. I do not know if that is a procedure used for the 6.5 in range of driver.
Given the test box size there really isn't enough margin around the cutout to -- how to say-- have the backwave expand in an ideal way.
Though I wouldn't be using a double baffle now or later, I'm still curious as to how the pdf drawing handles the double baffle. If it is mounted on the rear, then a waveguide could be shaped on the cutout.
As to box size, the original suggested design from Fostex is quite small
in it's BR configuration. The design was featured in an article in Speakerbuilder years ago as well. I will dig that out and see if there's anything valuable in that.
I asked that Madisound expedite delivery and they advised that they'd process the order same day. A very good company. And a local business here in Wisconsin, US.
Also is there any discussion about driver offset for the pdf design?
I'm wondering if some of these various things from GM and yourself can come together.
Though I wouldn't be using a double baffle now or later, I'm still curious as to how the pdf drawing handles the double baffle. If it is mounted on the rear, then a waveguide could be shaped on the cutout.
As to box size, the original suggested design from Fostex is quite small
in it's BR configuration. The design was featured in an article in Speakerbuilder years ago as well. I will dig that out and see if there's anything valuable in that.
I asked that Madisound expedite delivery and they advised that they'd process the order same day. A very good company. And a local business here in Wisconsin, US.
Also is there any discussion about driver offset for the pdf design?
I'm wondering if some of these various things from GM and yourself can come together.
Well, I've already pointed out that the driver is surface mounted -I'm not sure what else isn't in the drawing WRT the doubled front baffle.
WRT zdriver in my cabinet, you could lower it somewhat to 16.66in if you wished (I know the plan's in metric, but I still prefer Imperial), which should put it in the location favoured by GM from the operating POV. However, as a matter of practicality, with a cabinet only 45in tall, this might mean it's a trifle low at just over 28in off the ground, plus the thickness of the base & any plinth you might use. YMMV as always.
WRT zdriver in my cabinet, you could lower it somewhat to 16.66in if you wished (I know the plan's in metric, but I still prefer Imperial), which should put it in the location favoured by GM from the operating POV. However, as a matter of practicality, with a cabinet only 45in tall, this might mean it's a trifle low at just over 28in off the ground, plus the thickness of the base & any plinth you might use. YMMV as always.
holdent said:
Longer/larger cab = better damped around Fb also. Done right, 'BIB' always rules IMO.
That said, as I kept repeating WRT the short Vs long Jordan MLTLs, my 'default' way to calc MLTLs dictates a shorter/'fatter' pipe which is technically a superior alignment, so would never have considered pushing a driver with the 167's specs this far below Fs in a ~max flat alignment if SS driven, but of the folks who've built both Jordan versions only one preferred the short version IIRC, so as B0$3 and the SET tube aficionados have proven beyond a shadow of a doubt that in general we prefer resonant distortion over signal reproduction accuracy as long as it's euphonic.
Considering how 'dry'/'sterile' many (most?) CDs sound and the lack of much linear excursion, there's much to be said for SET tube based systems for 'FR' driver speakers if you're willing to sacrifice some transient response with other than horn drivers, though to take max advantage of them requires tunings that account for the added series resistance and impedance matching characteristics.
Anyway, WRT suggesting such a tall pipe to get the driver up to a more optimum height, my 'default' alignment is 'only' 33" long i.d. and with the driver at 13.875" down this dictates too tall a stand or mass loaded cavity for any effective floor vent loading, which may/may not be desirable depending on the app. Not being familiar with the app or have the other person's hearing quirks, I prefer to err on the side of excess since it's easier to shed it than gain it after assembly.
Speaking of which, when I was approached for a long Jordan variant I just stretched the basic design and it proved a crowd 'pleaser', so in retrospect, in keeping with this format the 56" version should be:
L = 56"
CSA = 119.32"^2
zdriver = 20.61"
dport = 4"
Lport = 1"
Bottom firing vent spaces it up to ~2.85".
GM
loninappleton said:
I assume the 144 cm is actually 14.4 cm and the driver hole cutout diameter.
Anyway, for this cab I calc the driver at ~9.7", but looks 'good enough' at 8.5" since the cab is acoustically small, so probably not worth changing it.
I recommend sticking with a 2" vent and experimenting with up to 6" long vents.
GM
Scottmoose said:
Still catching up here.
So the drawing lines of the speaker go all the way through to the baffle. Ok on that.
Also the revised measurement for lowering the driver is welcome because the goal is to get the down firing port as far up as is
doable. So a higher stand rather than lower is the target. The port location on one of my stands is at what I figure is the ideal:
25 in up.
I have cleared the idea of having to have the driver at ear height
and ready to compensate for these other positioning options.
Now to get if there's anything on driver offset and a round port measure.
When I think of buying a speaker for $80 I start to think: Lon what have you done?
But truth to tell the 127e has advanced in price over the years.
Perhaps now is a good time to avoid the next bump.
With this new activity, I may take the plunge and Damar one of my FE127e's and buy one of the EnAbling kits. I have already done a couple of cheapies with Damar.
GM said:
Good deal-- not much to buy then.
I hope the new discussion will be helpful to others. Aside from talk about open baffles the discussion has been kind of sparse in here.
I don't really know if I can take 'menu items' on this.
The last bit of option that we talked about was driver offset.
What would that add or detract from an MLTL like this?
Hi guys, I think Lon is asking whether there's a benefit to mounting it a little to the left or right, rather than dead center, maybe to spread the diffraction across a broader range of frequencies?
To my newbie mind, it seems easier to try to cut down on the diffraction altogether by applying felt to the baffle. At least it's reversible!
I remember reading about a series of blind tests along those lines (maybe in Loudspeaker Cookbook?) where basically, the listeners could tell the difference but it wasn't necessarily perceived as an improvement.
To my newbie mind, it seems easier to try to cut down on the diffraction altogether by applying felt to the baffle. At least it's reversible!
I remember reading about a series of blind tests along those lines (maybe in Loudspeaker Cookbook?) where basically, the listeners could tell the difference but it wasn't necessarily perceived as an improvement.
Ah! Ok, I'm a firm believer of offsetting drivers when the driver's BW can set up standing waves, especially on the larger cabs I'm more use to, i.e. BW too low for felt or similar to work well. Otherwise, a damping ring or even just a vertical strip on one side of the driver(s) suffices. The key is getting the right density. The dense 3/4" Jute padding that use to be under premium auto and home carpeting works well, though I imagine the thick hi-tech composites PE, etc. sells is probably just as good as whatever NHT used: http://www.stereophile.com/images/archivesart/99nht331.jpg
GM
GM
break in begins
The 167 actually did make it here the day after order (order at 2 pm or so.)
For what I'm used to handling it is huge.
And with this delicate instrument I have constant fear of damaging something. So I've been handling it in the shipping bag.
I've already put the driver in a break in box.
There's an a/b switch here that I can put the unit on the unused side and then crank the volume when I'm gone then return to music listening back here in the shop.
The noise will not bother anyone. Flipping on AM I can find a pretty good white noise unused frequency.
It can't go too loud because it's hooked up to a hacked boombox with three watts output.
The 167 actually did make it here the day after order (order at 2 pm or so.)
For what I'm used to handling it is huge.
And with this delicate instrument I have constant fear of damaging something. So I've been handling it in the shipping bag.
I've already put the driver in a break in box.
There's an a/b switch here that I can put the unit on the unused side and then crank the volume when I'm gone then return to music listening back here in the shop.
The noise will not bother anyone. Flipping on AM I can find a pretty good white noise unused frequency.
It can't go too loud because it's hooked up to a hacked boombox with three watts output.
I've done a sample fit of the driver and found at least one oddity.
The old website and pdf info says 14.4 cm (metric right?) or 144 mm.
and the packaging says 146 mm cutout.
Well, I had the the 144 mm cutout made on the practice test cut.
Fitting the driver in there (with all the problems of handling I mentioned above) the 144 cutout seemed adequate and I could feel
the driver move freely a bit.
But-- and here's the question for other 167e and other users:
Why is the flange a bit extended above the surface? Is this the reason Bob uses washers under the flange for leveling?
Where is my error?
I have not screwed the driver down yet because I'd like to get some good finishing hardware for a change ( see newer post on that.)
Break in continues and will for prob'ly a couple weeks.
The old website and pdf info says 14.4 cm (metric right?) or 144 mm.
and the packaging says 146 mm cutout.
Well, I had the the 144 mm cutout made on the practice test cut.
Fitting the driver in there (with all the problems of handling I mentioned above) the 144 cutout seemed adequate and I could feel
the driver move freely a bit.
But-- and here's the question for other 167e and other users:
Why is the flange a bit extended above the surface? Is this the reason Bob uses washers under the flange for leveling?
Where is my error?
I have not screwed the driver down yet because I'd like to get some good finishing hardware for a change ( see newer post on that.)
Break in continues and will for prob'ly a couple weeks.
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