Another speaker thread

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shane
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#136 Re: Another speaker thread

Post by shane »

Wouldn’t that mean that the motor system would be free to drive the chassis in the opposite direction to the cone, taking the baffle with it and thereby turning the baffle into a sound source working in opposite phase to the cone?
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#137 Re: Another speaker thread

Post by Ant »

I thought the same after i thought about it some more, thats why i suggested a skeletal baffle with an epdm skin instead.
The driver needs to be rigidly mounted
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#138 Re: Another speaker thread

Post by Ali Tait »

shane wrote: Mon Feb 01, 2021 1:00 pm Wouldn’t that mean that the motor system would be free to drive the chassis in the opposite direction to the cone, taking the baffle with it and thereby turning the baffle into a sound source working in opposite phase to the cone?
I had similar thoughts when visiting Vic, he showed me a video where he checked this with a frequency sweep on the bass drivers he uses, there was no movement of the baskets until around 4 hertz or so(!) even with them just supported by cables. At that time the mid drivers he was using were again hung with cable, but were bolted together in a line array with some plates he'd made, so there appeared to be sufficient weight to prevent any apparent movement of the drivers, even at way higher SPL's than I'd ever use at home.

I'll give him a shout about this thread, he might have some useful updates on where's he's at now.
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#139 Re: Another speaker thread

Post by simon »

It does seem a leap of faith compared to conventional baffles. But I suppose the cone and motor unit are much lighter than the magnet and basket so there is significant inertia resulting in the cone moving rather than the rest of the driver???
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#140 Re: Another speaker thread

Post by simon »

Thanks Ali, it would be very interesting to get Vic''s perspective.
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#141 Re: Another speaker thread

Post by Vangelo »

Guys...Ali brought this thread to my attention. I guess it would help to reveal some of the reasoning behind how I got to this weird design.

Understand, first of all, I have no engineering/mathematical/electrical skills. All my experimentation has been trial and error. This has been an advantage because my ignorance freed me. Sure....some things did not work, but I found this out for myself the hard way and learned from it.
One of my lessons was the use of U-frames, H-frames etc. While they increased the bass, they also incited room modes and added nasty colourations in my room.

I learned the purest, most detailed bass was naked....and suspended naked even better!

Everyone will immediately think you cannot get real bass without a baffle. Well, I get plenty....gut shakingly deep with Kraftwerk, detailed & full of tone with jazz acoustic & cello. No boomy notes running into each other ....just tight definition with total separation. No room resonating in sympathy emphasising certain notes. The bass from the UM is totally controlled and does not interfere or spill onto the mids/highs
.
The bass in my system is totally sorted and a pleasure to experience. Wish I could say the same about the rest...........(well, getting there).
So, you can get bass using naked drivers....but not just ANY driver. Things I look for are low FS, middling QTS, big Xmax. If efficiency is low (under 90db) it must handle high power. A weighty cone, big motor and stiff suspension are what I look for. I automatically dismiss fabric surrounds with light efficient cones and I don’t want to argue about it. I wasted enough money on those before I became enlightened.

The UM18 is perfect. Unfortunately, by the time it reaches these shores, it doubles in price...and how I envy them across the pond. I have to add I have tried many drivers in this application: Dayton IB385, RSS390, AE18, Bishop 21. The UM18s will eat them all for breakfast. They are really special and so far, I have not found a similar driver I would consider, apart from maybe the Dayton RSS460....but these are expensive too. Some of you have experienced issues other drivers give you would not even think of.....like chuffy ventiliation. UM’s are sorted here.

So we have a driver...now need an amp. The Behringer NX6000D is perfect, and you will probably get away with only one. The fans need to be changed cos it is a noisy sucker....the only caveat. People worry about the quality of this amp. What is more important and critical is the DSP....especially how it is set up. And this is a minefield. I would say its easy to dismiss the drive units as being crap if you don’t get this right. Sure, you will get a result with a rough set up, but you wont bring out the refinement this system is capable of without proper set-up of the DSP. There are so many variables with crossover, gain & slope all interacting. I am still learning after 8 years experience. Lucky, the Behringer software (unlike Crown) is so intuitive to use in real time from a laptop, its easy to hear the effect of these changes, so simple to fine tune. Also lucky.....the UM18s require very little eq......they have no nasties.....

Really, not trying to step on anyones toes here or deny there is a god. This is my experience and happy to answer any q’s! Cheers, Vic
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#142 Re: Another speaker thread

Post by Ali Tait »

Thanks for taking the time Vic. I can echo the comments on the quality of the bass, and I still remember that live Kraftwerk track. Never had a domestic hifi put me closer to the live event than that did.

Nick, Vic sent me a link to a thread which may be of interest if you haven’t seen it already-

https://www.diyaudio.com/forums/full-ra ... sures.html
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#143 Re: Another speaker thread

Post by ed »

it's now 95 years since Kellogg and Rice came up with that infernal invention.

what struck me as odd is that since that earliest of times so much effort has been spent putting the loudspeakers in all sorts of boxes. There have been a myriad of different types of boxes and half boxes and baffles and a myriad of arguments about which is best.

This is the first real exposure of loudspeakers without boxes that I have seen, and if what Vic says about the quality of freedom(I have no reason to doubt his findings) then why hasn't this been championed(pursued) at all during the last 95 years. After all, no box is much simpler than some box.

just voicing those random thoughts again.
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#144 Re: Another speaker thread

Post by simon »

Thanks for contributing Vic. Everything you and Ali say is very compelling! If I do end up down the DSP road this is at the top of my list.

I'm interested that you've tried the AE Dipole 18 (I think?) They look to be ideal for OB but they're not cheap. What did you make of them?
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#145 Re: Another speaker thread

Post by simon »

Ali Tait wrote: Tue Feb 02, 2021 10:59 am
Nick, Vic sent me a link to a thread which may be of interest if you haven’t seen it already-

https://www.diyaudio.com/forums/full-ra ... sures.html
Great, another long thread to digest :-D
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#146 Re: Another speaker thread

Post by simon »

ed wrote: Tue Feb 02, 2021 1:45 pm This is the first real exposure of loudspeakers without boxes that I have seen, and if what Vic says about the quality of freedom(I have no reason to doubt his findings) then why hasn't this been championed(pursued) at all during the last 95 years. After all, no box is much simpler than some box.
No baffle is inefficient relatively, and needs EQ. Perhaps modern electronics and production has made these feasible in a way it wasn't previously???
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#147 Re: Another speaker thread

Post by Nick »

simon wrote: Tue Feb 02, 2021 1:53 pm
Ali Tait wrote: Tue Feb 02, 2021 10:59 am
Nick, Vic sent me a link to a thread which may be of interest if you haven’t seen it already-

https://www.diyaudio.com/forums/full-ra ... sures.html
Great, another long thread to digest :-D
Indeed, I started reading it but lost the will to live. Maybe we should form a company that outsources reading of long articles and provides a summary. Bit like Gartner claim to do but never do.
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#148 Re: Another speaker thread

Post by Scottmoose »

simon wrote: Tue Feb 02, 2021 1:57 pmNo baffle is inefficient relatively, and needs EQ. Perhaps modern electronics and production has made these feasible in a way it wasn't previously???
Rather, say, they've made it cheaper. An unbaffled raw drive unit is the most inefficient way you can use it, solo (I stress I'm using the term in the factually neutral sense, not the pejorative). Since there is no baffle / baffles or enclosure the acoustic short-circuit between the front / rear radiation is defined purely by basket diameter so it naturally starts at a higher frequency than would otherwise be the case. As a result, you need a driver with a low Fs, a long throw and either a higher Q to help compensate a bit, or one with a low Fs, a long throw, significant EQ and lots of power -all the traits Vic notes. The higher Q bit has its limits & purely in FR terms is ultimately a balancing act between the driver size, its mass-corner frequency & avoiding excessively narrow peaking as Q becomes increasingly larger. It's only been in the past few years with the rise of inexpensive digital EQ and class D amplifiers that things like this have become more practical -you could do it before, but the power was more expensive & relatively fewer people had access to (or the skill to design) active EQ systems / circuits of sufficient capability.
Last edited by Scottmoose on Tue Feb 02, 2021 10:40 pm, edited 1 time in total.
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#149 Re: Another speaker thread

Post by Vangelo »

simon wrote: Tue Feb 02, 2021 1:52 pm Thanks for contributing Vic. Everything you and Ali say is very compelling! If I do end up down the DSP road this is at the top of my list.

I'm interested that you've tried the AE Dipole 18 (I think?) They look to be ideal for OB but they're not cheap. What did you make of them?
Hi Simon

Look great on paper....but I found them delicate and weak. Fall into the light cone fabric surround category...93db 150W. I bottomed them out easy.
I gather they are great at crossing high, but mine are tucked into a corner gathering dust. Also, AE dont publish a Frequency Response graph. Be nice to know roll off.....but then again, the high QTS was too cuddly for me. I prefer a lower QTS driver that will take eq to give some control.
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#150 Re: Another speaker thread

Post by Vangelo »

ed wrote: Tue Feb 02, 2021 1:45 pm it's now 95 years since Kellogg and Rice came up with that infernal invention.

what struck me as odd is that since that earliest of times so much effort has been spent putting the loudspeakers in all sorts of boxes. There have been a myriad of different types of boxes and half boxes and baffles and a myriad of arguments about which is best.

This is the first real exposure of loudspeakers without boxes that I have seen, and if what Vic says about the quality of freedom(I have no reason to doubt his findings) then why hasn't this been championed(pursued) at all during the last 95 years. After all, no box is much simpler than some box.

just voicing those random thoughts again.
Celestion did make an attempt in the 80s
Image
I dont think it sold very well because it wasn't boxed.....

Personally, I was inspired by this modern design:
Image

Until we start accepting that some of these 'out of box' might actually sound good they are doomed to fail.........
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