As in a 1.5 way.. Different woofers can be used for 1.5 way. This way you can even tune the baffle compensation level.
If you have a standard amplifier though, a capacitor across the lower driver increases the output of the upper driver, so it doesn't do baffle step. Use an inductor on the lower woofer in that case.
This subject reminds me of a now long gone pro studio monitor that I did an 'el cheapo' (RS) clone of where the 'FR' drivers were horizontally toe'd in to cancel out at 'X' mean frequency @ 'y' horizontal axis with a piezo horn ~as large as the 'FR' driver's baffle and once in the 'sweet spot' like one needs in a studio it was quite a revelation in that once bound up in a tightly stretched stocking type 'bootie'/sock (a significant contribution) it fooled many a ~ self proclaimed 'golden ear'.
So once again, proof that 'critically' damping a system can solve a multitude of design 'sins'/compromises. 😉
Yes. I missed that.
Looking at the published impedance and simulating a baffle step like this...
Each component does a different thing. The resistor shelves the treble level. The inductor sets the midrange level. The capacitor changes the split between the two drivers, without changing the response too much.
Looking at the published impedance and simulating a baffle step like this...
Each component does a different thing. The resistor shelves the treble level. The inductor sets the midrange level. The capacitor changes the split between the two drivers, without changing the response too much.
Nice application -especially with that piezo horn. 🙂 Shows what was possible with those (much missed) RS units too, bit like your old 1354 MLTL did.
Yeah, I've done a handful of designs using twin / multiple units that have worked out reasonably-reasonable. The semi-stillborn Viotti Tower ran a pair of mid-tweets, albeit further apart than I would have liked. It needed a bit more refining in the filter, which I didn't have time to do before the shutters rolled down on the company, but it wasn't too bad as-was. Bit limited > 12KHz, but aside from that lack of 'air' it was pleasant & it kicked surprisingly well. I've still got a prototype pair in storage -might have to put them back together. Minor story behind this thing I'll tell you elsewhere. 😉
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All around getting 2 matching drivers.
On one baffle with simple filter, to make it happen.
Is pretty fun project.
With wide baffle, might be able to weasel around
to much baffle step compensation.
With skinny baffle can mount one driver 90 degree or side mount.
Usually just one coil for filter. sums pretty flat
Always leads to previous comment.
Just add larger woofer instead.
Staying to the concept.
Be fun to stick to some rule.
2 matching drivers ,one box
make it work.
fun guideline to play with.
On one baffle with simple filter, to make it happen.
Is pretty fun project.
With wide baffle, might be able to weasel around
to much baffle step compensation.
With skinny baffle can mount one driver 90 degree or side mount.
Usually just one coil for filter. sums pretty flat
Always leads to previous comment.
Just add larger woofer instead.
Staying to the concept.
Be fun to stick to some rule.
2 matching drivers ,one box
make it work.
fun guideline to play with.
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I've often wondered about this configuration...
With the second driver facing straight up, and in a typical 7 ft high room (about 2.5 meters), would ceiling bounce be a problem?
My question about the front/back firing pair is, are there phase artifacts with certain frequencies cancelling out? Or does one attenuate the rear-firing driver to suit the room situation?
With the second driver facing straight up, and in a typical 7 ft high room (about 2.5 meters), would ceiling bounce be a problem?
My question about the front/back firing pair is, are there phase artifacts with certain frequencies cancelling out? Or does one attenuate the rear-firing driver to suit the room situation?
I have a set like the up firing ones. I haven't found the ceiling bounce to be a problem, but I use them as surrounds, which I think they are very good at. Much better than dipoles/bipoles/monopoles hanging on the wall. Place them slightly below the ear and facing behind you. The center rear can be a tri-pole.
I've made several bipoles and they sound great but need to be at the right distance from the wall. Yes there is cancellation, addition and other artifacts from running two speakers facing away from each other. Personally I like the effect of bipoles it's more expansive and deep.
There is no need to attenuate the rear driver.
Also bipole sub-woofers absolutely rock! Four 8" sub drivers in two bipole enclosures set along the front wall and you have boom-shaka-laka BOOM!
I've made several bipoles and they sound great but need to be at the right distance from the wall. Yes there is cancellation, addition and other artifacts from running two speakers facing away from each other. Personally I like the effect of bipoles it's more expansive and deep.
There is no need to attenuate the rear driver.
Also bipole sub-woofers absolutely rock! Four 8" sub drivers in two bipole enclosures set along the front wall and you have boom-shaka-laka BOOM!
Here's a comparison of a ~ 3.5" driver by itself and two drivers at a 85mm/3.34" distance center to center.
Single driver first:
Compared to the two drivers:
See how the vertical listening window narrows on the top end? You also see some lobes of sound in the vertical window that will hit the floor and ceiling and come back at the listening position. The driver you propose is an even bigger framed driver (driver frame 6.75") which makes this center to center distance even larger. That larger distance by itself wil create an even more narrow vertical listening window.
Changing nothing but the distance between the drivers to 6.75" center to center:
Aside that, the bigger driver will have a less wide directivity at it's top end due to it's size, so it'll be worse than shown here.
Hope this helps to answer some part of your question.
The tool used here is VituixCAD, an excellent program that can help us understand what will happen in cases like this. Developed by fellow forum member @kimmosto and offered free of charge for us DIY nuts. Highly recommended by this nut (me) that put 25 x ~3.5" drivers in a row and used this tool extensively to learn from it.
The upfiring driver essentially gives you an acoustic low-pass, making filters unnecessary. The 2 drivers are also physically closer.
A bipole run full range will have a bipole dip. Given their typical application, as a sort of omoi that fills the room, so FR tends to be a bit wonky andit is unlikely to be noticed.
dave
No…..and the farther apart they are, the worse the comb filtering will be.
4” is not a woofer………your goal appears to be more SPL and headroom so use the 4” as the full range and use a larger driver designed for bass duty with it. Use a simple 1st order filter. OR……use 1 driver per side and supplement the bass with a subwoofer.
You CAN use two identical drivers per side but I cannot see any value in using a driver designed for full range to supplement the lower end…..these driver types typically have light cones and very limited excursion…..not something you want for bass duty.
I am experimenting in the same manner. I have a setup with two Lowther BLH's with a Fostex 208Sigma (whizzer cone version). Furthermore, I
recently acquired a similar pair of these Fostex. Is something like this config from Lowther an option?
The reason I'd be interested in using two wide-range drivers in a single cab would be to increase sensitivity and raise load impedance for use with a low power tube amp with little or no NFB applied. I'd wire the two drivers in series to double the load impedance they present. Tube amps with low NFB generally work better into lighter loads.
A friend of mine has a pair of older model Jordan drivers in front-firing vertical pairs, with an 8" Jordan woofer each side. They sound great if you're sitting 10 or 12 feet away, which is the case in his listening room. I sit closer, though, which would prevent me from using that particular design, I think.
Does using a rear-firing driver w/o filtering increase sensitivity to any appreciable degree?
A friend of mine has a pair of older model Jordan drivers in front-firing vertical pairs, with an 8" Jordan woofer each side. They sound great if you're sitting 10 or 12 feet away, which is the case in his listening room. I sit closer, though, which would prevent me from using that particular design, I think.
Does using a rear-firing driver w/o filtering increase sensitivity to any appreciable degree?
It could be said that it increases sensitivity by 3dB, rather than the 6dB we'd count if they were constructively additive in a more consistent way. This is due to the power relationship taking precedence. However, it isn't as simple as that in reality.
Hmmm.... Does that mean using an up-firing driver helps mitigate the tendency of wide-range drivers to have rising response as frequency increases? If so, the up-firing driver design might be a simple way to get good results from a couple of wide-range drivers in a single cabinet, while sticking to the 'no crossover' ideal. (I'd probably look at installing some kind of BSC, though.)
I'd take a 2dB increase in sensitivity. 3dB even better.
The higher impedance should make the speaker more tube friendly, so it seems there's nothing significant screaming "DON'T DO THIS!!" Right?
Then i woulod recommend a catle arrangement like Akira’s (i’d try to get the drivers closer)
adding a 2nd driver in series gives you 3dB more efficiency but lose 3dB.
dave
3dB more sensitivity but at the cost of 3dB from power loss due to the increased impedance. IOW, if you have the watts, you can concentrate on the gain rather than the loss.
Personally, I am happy with the front and rear, or front and top configuration.