There is another effect taking place when comparing “swing” versus “metronome” (the NAIM Ovator S600) I haven’t outlined in detail yet.
But as there seems to be some interest here to explore the topic in a very practical way, I’d better hurry up to complete with what I’d consider to be the second order effect of a second order effect.
To make things "simple" lets assume to compare a pretty ideal pendulum (mass on a string) to a pretty ideal metronome.
Now if we put the Metronome upside down we also get a pendulum with the only difference that this one has a rigid rod between mass and pivot compared to a (close to ideal) pendulum that's using a flexible string (chain, steel wire, etc).
There is a significant difference in the forces involved for the two cases.
In case of the stiff structure pendulum (metronome) there is an *additional* movement involved as the speaker *has to tilt* up and down when moving forth and back.
(imagine of a flashlight to be attached sideways at the pendulum if you have problems to visualize kinematics)
We can decompose that – additional – movement as to be a
1. rotation around a horizontal axis (= the pivot of the pendulum) plus
2. an up and down movement
Certainly – the “an up and down movement” we also have with a swing of course – but point one “rotation around a horizontal axis” we not necessarily have.
Either with the string (steel wire chain) attached close to mass centre – or with double swings - one behind the other - for example.
The point I want to make is that that tilting movement has to be accomplished by a reaction force of the pivot that is not there, when hung a mass on a string
This force must be transmitted through the whole structure from the speaker to the pivot point and back to the speaker again, to make the speaker "rotate".
This force may not be exactly huge (haven't calculated yet) - especially not for a fairly compact mass of a nude speaker - but it *is* there and may cause an audible difference especially with larger "parasitic" masses involved.
#########
For the case of "soft pivots" like your rubber balls of pads or tire tube (great - LOL) things are a little bit more complex but nevertheless follow the same rules (plus what already said in 434)
Bottom line - the structure of the speaker has to transfer that additional energy and most certainly we will be plagued with additional resonance in that structure, radiating into the room
Michael
But as there seems to be some interest here to explore the topic in a very practical way, I’d better hurry up to complete with what I’d consider to be the second order effect of a second order effect.
To make things "simple" lets assume to compare a pretty ideal pendulum (mass on a string) to a pretty ideal metronome.
Now if we put the Metronome upside down we also get a pendulum with the only difference that this one has a rigid rod between mass and pivot compared to a (close to ideal) pendulum that's using a flexible string (chain, steel wire, etc).
There is a significant difference in the forces involved for the two cases.
In case of the stiff structure pendulum (metronome) there is an *additional* movement involved as the speaker *has to tilt* up and down when moving forth and back.
(imagine of a flashlight to be attached sideways at the pendulum if you have problems to visualize kinematics)
We can decompose that – additional – movement as to be a
1. rotation around a horizontal axis (= the pivot of the pendulum) plus
2. an up and down movement
Certainly – the “an up and down movement” we also have with a swing of course – but point one “rotation around a horizontal axis” we not necessarily have.
Either with the string (steel wire chain) attached close to mass centre – or with double swings - one behind the other - for example.
The point I want to make is that that tilting movement has to be accomplished by a reaction force of the pivot that is not there, when hung a mass on a string
This force must be transmitted through the whole structure from the speaker to the pivot point and back to the speaker again, to make the speaker "rotate".
This force may not be exactly huge (haven't calculated yet) - especially not for a fairly compact mass of a nude speaker - but it *is* there and may cause an audible difference especially with larger "parasitic" masses involved.
#########
For the case of "soft pivots" like your rubber balls of pads or tire tube (great - LOL) things are a little bit more complex but nevertheless follow the same rules (plus what already said in 434)
Bottom line - the structure of the speaker has to transfer that additional energy and most certainly we will be plagued with additional resonance in that structure, radiating into the room
Michael
Last edited:
Holly s**
In case you have bad luck with these too - PM me, and I send you either a tube repair kit or a piece of steel wireMichael
Last edited:
My foam pads collapsed, too
But they are not totally dead yet, still provding some compliance...
I feel such feet should be as soft as possible, meantime they must last longer to be practical. (Cork is too stiff I guess.)
Say, is it possible to find (define) an actual pivot point at the bottom? For example, 1 or 2 rollers (or glass/steel balls, spikes, whatever) at about the midpoint of the bottom area to provide stiff and rotatable support against gravity, and 2 groups of soft supports at front and back to provide compliance against fore-aft rotation. Will it work? Or too complex?
But they are not totally dead yet, still provding some compliance...
I feel such feet should be as soft as possible, meantime they must last longer to be practical. (Cork is too stiff I guess.)
Say, is it possible to find (define) an actual pivot point at the bottom? For example, 1 or 2 rollers (or glass/steel balls, spikes, whatever) at about the midpoint of the bottom area to provide stiff and rotatable support against gravity, and 2 groups of soft supports at front and back to provide compliance against fore-aft rotation. Will it work? Or too complex?
If you build them up creatively you will be very surpriced
You need the right size
They right number of layers
And the right material between he layers
Use it as feet on your electronics as well
And with granite as base
Try to hit a piece of cork with hammer, and you will hear why
Last edited:
My foam pads collapsed, too
But they are not totally dead yet, still provding some compliance...
I feel such feet should be as soft as possible, meantime they must last longer to be practical. (Cork is too stiff I guess.)
Say, is it possible to find (define) an actual pivot point at the bottom? For example, 1 or 2 rollers (or glass/steel balls, spikes, whatever) at about the midpoint of the bottom area to provide stiff and rotatable support against gravity, and 2 groups of soft supports at front and back to provide compliance against fore-aft rotation. Will it work? Or too complex?
Way too much friction even if you would take ball bearings IMO...
To repeat - any dampening material is contra productive to get best impulse compensation.
Its the possibility to move *freely* that makes the swings work so well and calms down resonating movement - NOT any sort of dampening !!!
I know - this isnt any intuitively to most of you - but in doubt try or read my paper
#########
Why not take three pieces of MDF, slap it together to form a U-shape and put your H-sub into?
Make the U-shape roughly the heigh of your H-sub - roughly the width of your H-sub (add some 1cm / 1/2" of play each side) - sligtly less the depth of your H-sub.
Wrap a rope or steel wire around to lift the H-sub some 1cm / 1/2" from the U-shape and you are done.
No big deal...
Michael
Last edited:
No small deal, either for me.
I've already used swing on my mid-high section of the system. I know that's working perfectly even if my swings are not perfect. Now dealing with the bass, it's rather big and quite heavy (4* 18"ers in total in my case). I'm working on some solutions (on paper) of real swings for bass, but I've not come to a good compromise yet.
So, rather than revolution, now I'm taking evolution first to see what happens. And it turned out very good, better than I expected So I'd like to let it evolve for a while. 
for me.I've already used swing on my mid-high section of the system. I know that's working perfectly even if my swings are not perfect. Now dealing with the bass, it's rather big and quite heavy (4* 18"ers in total in my case). I'm working on some solutions (on paper) of real swings for bass, but I've not come to a good compromise yet.
So, rather than revolution, now I'm taking evolution first to see what happens. And it turned out very good, better than I expected
So I'd like to let it evolve for a while. Michael, you provide some really interesting ideas here! It makes sense to me that the point is to let the speaker and/or baffle move as freely as possible, and that any suspension should let it do just that.
I will try some bicycle tire tube tonight, will let you know how that works. If no greater success, I guess I have to build a kind of swing for the H-baffle as well.
This is by far the most "different" (from the standard - oh so boring - box-type) speaker project I've ever done, and I've never had this much fun with a speaker project ever! Its also by far the best sounding speaker I've build.
I'd like to thank all of you who have contributed in this thread, you have provided invaluable help for me. Thank you very much!
It makes sense to me that the point is to let the speaker and/or baffle move as freely as possible, and that any suspension should let it do just that.I will try some bicycle tire tube tonight, will let you know how that works. If no greater success, I guess I have to build a kind of swing for the H-baffle as well.
This is by far the most "different" (from the standard - oh so boring - box-type) speaker project I've ever done, and I've never had this much fun with a speaker project ever! Its also by far the best sounding speaker I've build.
I'd like to thank all of you who have contributed in this thread, you have provided invaluable help for me. Thank you very much!
I've had this idea as well. Some of those are made from Sorbothane, which have excellent damping properties. But as Michael said, damping is not what we need really.
Makes it a bit difficult to move them around.....Hang them from the ceiling...
Problem solved
Rock N' Roll, without resonance...!
Hi all,
I have been experimenting with free air driver suspension with thin steel wire or soft polypropylene rope, and the benefits & compromises involved when combining the hanging driver with a baffle.
My initial conclusions are as follows:
I can’t hear or measure any difference between thin steel wire ( stainless steel shark trace from fishing tackle shop) and good soft polypropylene rope. But I can feel a slight vibration in the steel wire. I cannot feel any vibration in soft rope. The wire looks best, very cool!
Using traditional “soft mounting” I tried using a 3mm Sorbothane gasket between the Manger and the back of the solid wood horns, but the brass screws created an effective energy path for vibrations and I could still feel the (25Kg!) wooden horns vibrate slightly.
Next I built a “zero contact” wooden clamping system ( photo attached) lined with 3mm Sorbothane to attach the Manger driver to the back of the solid wood horns.
There are no bolts or screws going through the Manger chassis, only bolts / threaded inserts going through the wooded mounting plate and the wooden horn.
The Manger chassis sits in a sleeve of 3mm Sorbothane, no part of the Manger is in contact with any wood, clamp or horn, and no bolts or screws touch or pass through the Manger chassis.
The wooden clamp is tightened only to “finger tight”.
This is a total success and there is now Zero vibration detectable in the wooden horn.
There was a small but worthwhile improvement in the sound. I am only speculating here but I think the very heavy and solid wooden horns will show less of an improvement than a conventional 18mm or 25mm thick flat baffle.
I have found it much more difficult to implement the zero contact clamp when working with heavy 15 inch and 18 inch drivers. They are so heavy...!
My best results were obtained using a rear mounting zero contact soft mount combined with rope or wire suspension wrapped around the central pivot, close to where the magnet meets the chassis.
Then only a very gentle pressure or forward facing support is required to make the seal between the front of the driver and the rear of the baffle.
3mm Sorbothane combined with 3mm neoprene under floor sound deadening material is required to completely encapsulate the edges of the metal chassis.
The really sweet part is this, you can now build a fully open baffle cabinet of almost any shape and size ( trapezoid VPL in my case) and hide all the mechanical suspension, rope and wires by hanging the drivers from the underside of the top plate and or an internal cross brace running from one side or “wing” to the other.
So it will look just like a normal cabinet from the outside but it will benefit from all the sonic advantages of a fully suspended driver array!
You get all the advantages of pristine midrange and high frequencies plus clean deep extended bass from a baffle and or a folded baffle without any of the sonic disadvantages i.e. this completely isolates the driver from the baffle and therefore eliminates all the nasty cabinet vibrations and resonances.
This now finally clears the way for my ultimate goal, a high WAF, 3 way open baffle low mid / bass system combined with a front loaded horn for the Manger.
This speaker will rock, but not resonate....!!
I will attach a photo in another post of my sub 400Hz test baffle, please note the ultra high tech tubular foam edges to eliminate cabinet edge nasties, huge cost £2.99 at B&Q for a pack of 5....!
All the best
Derek.
Hi all,
I have been experimenting with free air driver suspension with thin steel wire or soft polypropylene rope, and the benefits & compromises involved when combining the hanging driver with a baffle.
My initial conclusions are as follows:
I can’t hear or measure any difference between thin steel wire ( stainless steel shark trace from fishing tackle shop) and good soft polypropylene rope. But I can feel a slight vibration in the steel wire. I cannot feel any vibration in soft rope. The wire looks best, very cool!
Using traditional “soft mounting” I tried using a 3mm Sorbothane gasket between the Manger and the back of the solid wood horns, but the brass screws created an effective energy path for vibrations and I could still feel the (25Kg!) wooden horns vibrate slightly.
Next I built a “zero contact” wooden clamping system ( photo attached) lined with 3mm Sorbothane to attach the Manger driver to the back of the solid wood horns.
There are no bolts or screws going through the Manger chassis, only bolts / threaded inserts going through the wooded mounting plate and the wooden horn.
The Manger chassis sits in a sleeve of 3mm Sorbothane, no part of the Manger is in contact with any wood, clamp or horn, and no bolts or screws touch or pass through the Manger chassis.
The wooden clamp is tightened only to “finger tight”.
This is a total success and there is now Zero vibration detectable in the wooden horn.
There was a small but worthwhile improvement in the sound. I am only speculating here but I think the very heavy and solid wooden horns will show less of an improvement than a conventional 18mm or 25mm thick flat baffle.
I have found it much more difficult to implement the zero contact clamp when working with heavy 15 inch and 18 inch drivers. They are so heavy...!
My best results were obtained using a rear mounting zero contact soft mount combined with rope or wire suspension wrapped around the central pivot, close to where the magnet meets the chassis.
Then only a very gentle pressure or forward facing support is required to make the seal between the front of the driver and the rear of the baffle.
3mm Sorbothane combined with 3mm neoprene under floor sound deadening material is required to completely encapsulate the edges of the metal chassis.
The really sweet part is this, you can now build a fully open baffle cabinet of almost any shape and size ( trapezoid VPL in my case) and hide all the mechanical suspension, rope and wires by hanging the drivers from the underside of the top plate and or an internal cross brace running from one side or “wing” to the other.
So it will look just like a normal cabinet from the outside but it will benefit from all the sonic advantages of a fully suspended driver array!
You get all the advantages of pristine midrange and high frequencies plus clean deep extended bass from a baffle and or a folded baffle without any of the sonic disadvantages i.e. this completely isolates the driver from the baffle and therefore eliminates all the nasty cabinet vibrations and resonances.
This now finally clears the way for my ultimate goal, a high WAF, 3 way open baffle low mid / bass system combined with a front loaded horn for the Manger.
This speaker will rock, but not resonate....!!
I will attach a photo in another post of my sub 400Hz test baffle, please note the ultra high tech tubular foam edges to eliminate cabinet edge nasties, huge cost £2.99 at B&Q for a pack of 5....!
All the best
Derek.
Attachments
Suspended 15' Precision Devices
Hi all,
In this rough test baffle the PD 158 is sweet from 200Hz to 400Hz.
Adding 160mm min depth, 330mm max depth, VPL side wings adds on a good octave or more ie 80hz to 400Hz with no sonic penalty of cuppy vocals and muddy low mids.
There will of course be a an additional 15' or 18' Beyma or Presion Devices driver covering the 80Hz down to approx 30Hz ( more room than driver dependant) band.
Over the Christmas break I hope to complete the drawings for the finished design.
Cheers
Derek.
Hi all,
In this rough test baffle the PD 158 is sweet from 200Hz to 400Hz.
Adding 160mm min depth, 330mm max depth, VPL side wings adds on a good octave or more ie 80hz to 400Hz with no sonic penalty of cuppy vocals and muddy low mids.
There will of course be a an additional 15' or 18' Beyma or Presion Devices driver covering the 80Hz down to approx 30Hz ( more room than driver dependant) band.
Over the Christmas break I hope to complete the drawings for the finished design.
Cheers
Derek.
Attachments
Indeed! Nice foam work!
Question for you. Is the baffle all foam, or foam covering something else?
Reason I ask is that I've always found foam to be rather transparent in the bass. But maybe not up were you are using it. What have you found?
(Sorry to butt in, been reading, but not posting).
Question for you. Is the baffle all foam, or foam covering something else?
Reason I ask is that I've always found foam to be rather transparent in the bass. But maybe not up were you are using it. What have you found?
(Sorry to butt in, been reading, but not posting).
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.