Multi Purpose Load Box and LineOut

For all things to build the brown sound

Moderators: VelvetGeorge, RACKSYSTEMS

jnew
Senior Member
Posts: 1577
Joined: Mon Jan 07, 2013 9:34 am
Just the numbers in order: 13492
Location: Front Row Seat From the Outer Continental Shelf

Re: Multi Purpose Load Box and LineOut

Post by jnew » Mon Mar 18, 2013 9:49 am

P3170002.JPG
P3170002.JPG (69.57 KiB) Viewed 2239 times
P3170001.JPG
P3170001.JPG (69.91 KiB) Viewed 2239 times
Finito. Clips to come soon.
________________________________
I SEE THINGS BETTER, WHEN I LISTEN


http://www.soundclick.com/bands/default ... ID=1214336" onclick="window.open(this.href);return false;

User avatar
MrBeasty
Senior Member
Posts: 639
Joined: Thu Jun 10, 2004 5:24 pm
Just the numbers in order: 7
Location: DC
Contact:

Re: Multi Purpose Load Box and LineOut

Post by MrBeasty » Mon Apr 29, 2013 2:14 pm

jnew wrote: Finito. Clips to come soon.
Oh yeah!? :whistle:

User avatar
rgorke
Senior Member
Posts: 4509
Joined: Fri Feb 08, 2008 11:37 am
Just the numbers in order: 13492
Location: Drought Ravaged SoCal

Re: Multi Purpose Load Box and LineOut

Post by rgorke » Tue Apr 30, 2013 5:50 am

MrBeasty wrote:
jnew wrote: Finito. Clips to come soon.
Oh yeah!? :whistle:
Come on buddy!!! Stay awake!!! :thumbsup:

http://forum.metroamp.com/viewtopic.php?f=16&t=41617" onclick="window.open(this.href);return false;.
"If you make a mistake, do it twice and smile and let people think you meant it." Jan Van Halen.

dirtycooter
Senior Member
Posts: 2923
Joined: Fri Oct 03, 2008 3:02 pm

Re: Multi Purpose Load Box and LineOut

Post by dirtycooter » Mon May 06, 2013 9:45 pm

I am wondering if Subwoofers couldn't be used as a reactive load???
If you put it in a iso box, completely enclose it, suck ALL the air out and vacuum seal it-then it should make virtually NO SOUND in theory. You need air for sound to travel-then you need reflective surfaces that can resonate sympathetically with the sub frequency wave to hear it. You never hear the sub anyway-you hear the things around it vibrate to the frequency it projects.
Thus it should be silent as well as reactive.
Am I smokin crack here? Or am I onto some kinda brainstorm idea?? :what:

User avatar
Dunkmop
Senior Member
Posts: 416
Joined: Tue Jun 16, 2009 5:13 pm
Just the numbers in order: 7
Location: UK

Re: Multi Purpose Load Box and LineOut

Post by Dunkmop » Tue May 07, 2013 3:03 pm

I thought about this also, but maybe not to the extent of a vacuum; as this will be hard to keep i expect.

I have a spare speaker I will never use, so I have thought about using it as a dummy load and just create a nice box to hide/insulate it away.

I suppose you could weld together a nice metal box and create a decent seal around it?!
Metroamp 12000
EVH 4X12 + Marshall 1960AX 6402
Gibson Les Paul
VH RWB Strat in Progress

dirtycooter
Senior Member
Posts: 2923
Joined: Fri Oct 03, 2008 3:02 pm

Re: Multi Purpose Load Box and LineOut

Post by dirtycooter » Tue May 07, 2013 6:23 pm

I was thinkin out of phase subs in an acrylic tube cylinder facing each other- I suppose steel or aluminum 12" tube would work.
You could put in a vacuum port in the middle to suck out the air.

Made me think of this mondo ass super sized lawn roller my buddy made from 1/4" boiler plate-its the heaviest lawn roller I ever seen-even not filled up yet. I think aluminum unfilled would still be ball breakin weight wise though. :scratch:

User avatar
ampSnob
Senior Member
Posts: 344
Joined: Thu Jan 05, 2006 6:15 pm

Re: Multi Purpose Load Box and LineOut

Post by ampSnob » Tue May 07, 2013 7:39 pm

dirtycooter wrote:I am wondering if Subwoofers couldn't be used as a reactive load???
If you put it in a iso box, completely enclose it, suck ALL the air out and vacuum seal it-then it should make virtually NO SOUND in theory. You need air for sound to travel-then you need reflective surfaces that can resonate sympathetically with the sub frequency wave to hear it. You never hear the sub anyway-you hear the things around it vibrate to the frequency it projects.
Thus it should be silent as well as reactive.
Am I smokin crack here? Or am I onto some kinda brainstorm idea?? :what:
It would work however, without air, the cone of the speaker would have nothing to react to. You could get the same effect by just taking an exacto knife to a speaker and cutting out the cone or something. It would probably sound and react the same as one of those weber motor loads. BTW- the speaker might overheat without air moving around cooling it off.

Now if you put the speaker in a room/tank with air like normal, and then put that whole contraption in another tank and sucked out all the air between the two tanks so no sound could leak out -- Like a big ass thermos -- Then you would have the perfect silent sound proof solution for the reasons you pointed out earlier. If anyone has any ideas on how to engineer this monster I'm all ears.

dirtycooter
Senior Member
Posts: 2923
Joined: Fri Oct 03, 2008 3:02 pm

Re: Multi Purpose Load Box and LineOut

Post by dirtycooter » Wed May 08, 2013 2:45 am

OK
still thinkin of the vacuum chamber but one step better would be like you mentioned about the coneless speaker motor.
Only here is the catch and I REALLY think it could work AND be compact.

Instead of havin the cone provide the flexing resistance-and the surround dampening it for resistive load

Why not create a circle of tiny springs that provide about as much or the resistance of a cone and make the motor work against that spring load plate?? No box, no air tricks, no bulk, and zero sound.
Inside of an automatic transmission there is a similar circular disc with coil springs all the way around its edge facing 90 dgr from the disc. The pressure apply plate. Its about 6" in diameter on most transmissions.
of course these are way more springs or resistance than we would need but it could be mathematically figured out testing a spring vs a cones resistance. You could figure out how many small tiny springs offer the same resistance as the cone. Just add or subtract springs to fine tune its resistance and find the right size of springs if need be.
Stiffer springs would equal stiffer cone. Less springs weaker cone. Also you could add variable pressure on the plate from the back side offering another tension adjustment fine tuning the resistance further via a worm gear or threaded collar in the center so you could compress the springs slightly more or less that the motor works against.
One big ass high wattage speaker say at 16ohms loaand a motor that could take 300-350watts heat easy could be tuned to sound like the reactive load of 4 greenbacks, 4 v30's, 4 h30's, etc etc. :scratch:

User avatar
ampSnob
Senior Member
Posts: 344
Joined: Thu Jan 05, 2006 6:15 pm

Re: Multi Purpose Load Box and LineOut

Post by ampSnob » Wed May 08, 2013 12:06 pm

I like it! Might work great. What about adding a dampener like memory foam or a sponge soaked in oil to keep the springy reverb effects to a minimum as they most likely get reflected back into the audio path and appear In the signal. might sound fantastic though, who knows. Also, I have no idea how memory foam would act in a vacuum.

User avatar
vanhalen5150
Senior Member
Posts: 7307
Joined: Wed Sep 10, 2008 3:13 pm
Just the numbers in order: 7
Location: Halifax, Canada

Re: Multi Purpose Load Box and LineOut

Post by vanhalen5150 » Wed May 08, 2013 3:51 pm

I'm going to seal my entire 4/12 with a Ronco food sealer. :P
12000 Metro Kit

jnew
Senior Member
Posts: 1577
Joined: Mon Jan 07, 2013 9:34 am
Just the numbers in order: 13492
Location: Front Row Seat From the Outer Continental Shelf

Re: Multi Purpose Load Box and LineOut

Post by jnew » Wed May 08, 2013 8:00 pm

There's an idea.
________________________________
I SEE THINGS BETTER, WHEN I LISTEN


http://www.soundclick.com/bands/default ... ID=1214336" onclick="window.open(this.href);return false;

jnew
Senior Member
Posts: 1577
Joined: Mon Jan 07, 2013 9:34 am
Just the numbers in order: 13492
Location: Front Row Seat From the Outer Continental Shelf

Re: Multi Purpose Load Box and LineOut

Post by jnew » Fri May 10, 2013 10:22 pm

Actually, now that I think about it, I'm not sure springs would work because I believe the speaker also has to move inwards. Not just a one direction movement of resistance but sort of out, in, and then returns to it zero position with resistance in both directions. :scratch:
________________________________
I SEE THINGS BETTER, WHEN I LISTEN


http://www.soundclick.com/bands/default ... ID=1214336" onclick="window.open(this.href);return false;

User avatar
vanhalen5150
Senior Member
Posts: 7307
Joined: Wed Sep 10, 2008 3:13 pm
Just the numbers in order: 7
Location: Halifax, Canada

Re: Multi Purpose Load Box and LineOut

Post by vanhalen5150 » Sat May 11, 2013 7:03 am

This is one of the problems I have with the whole induction thing. If you put a meter on a speaker and move the coil back and forth, it will create a charge through induction. Does this reflect back to the amp? Since speaker motors themselves have no magnet, how are they the same? I asked Webber this and they refered me to induction on Wikipedia. Without a magnet, are they the same? Webber says yes. :what:

Sometimes I wonder if anyone actually knows what they are talking about.
12000 Metro Kit

User avatar
ampSnob
Senior Member
Posts: 344
Joined: Thu Jan 05, 2006 6:15 pm

Re: Multi Purpose Load Box and LineOut

Post by ampSnob » Sat May 11, 2013 9:25 am

vanhalen5150 wrote:Sometimes I wonder if anyone actually knows what they are talking about.

Amen to that, don't believe any physicist that says they know 100% exactly what's going on. The exact nature of it all is still a mystery. Egghead types have a hard time admitting this. However, we do know enough to build useful things like motors, solenoids speakers etc. Having said all that, let me try to answer your questions pretending to know what I'm talking about
vanhalen5150 wrote:This is one of the problems I have with the whole induction thing. If you put a meter on a speaker and move the coil back and forth, it will create a charge through induction. Does this reflect back to the amp?
Short answer: If there's no speaker hooked up, then yes. If the speaker is plugged in, then it takes that induced voltage/current and makes noise with it.


Long answer: Before I get into that I have to point out an vital piece of physics info. A moving charge has a magnetic field that goes with it. That is to say, a wire with current going through it has a circular magnetic charge surrounding the wire. (google "Oersted compass wire experiment") Now if you wrap that wire into a bunch of loops, you focus that magnetic field to the middle of the coil (technically a dipole configuration) Throw in a soft iron core into that, or transformer laminations, and that magnetic field is focused even more.

The second piece of vital info: Conductors (like metal) hate it when a magnetic field changes near them either by growing or moving. (or when the metal itself moves around a magnetic field, it's all relative) Stationary magnetic fields are of no interest here, but for some reason a CHANGING a magnetic field causes special things to happen. When a magnetic field grows/moves, a metal conductor will magically try and move its internal electrons in such a way to generate an opposing magnetic field whose purpose it is to neutralize that initial intruding magnetic field change. This additional movement of electrons is induced current and opposes the initial current. Clever transformer/inductor makers harness this phenomenon to do useful work and make fun things happen. In a transformer, this current allowed to flow but in a different coil (the secondary) and then is passed along to a speaker to make noise. In an inductor (or a transformer with an open secondary which is the exact same thing as an inductor) that current has nowhere to go so it manifests itself only as an opposing voltage in the primary. Hence 'smoothing' out any changes in the voltage AKA letting more low frequencies through as opposed to high frequencies AKA low pass filter. However, that initial magnetic field does end up growing (unlike the transformer where the magnetic field gets to neutralize itself) This magnetic field is in fact energy stored as magnetism because the current IS flowing even though the voltage is appearing to hold more steady due to the opposing voltage being created.

As you know AC energy switches polarities frequently and when that initial source of current stops feeding in, there is a bizarre state of magnetism that has to be dealt with. This magnetic field that has struggled so hard to grow now does NOT want to shrink and once again opposing voltages are created to fight to keep this magnetic field from going away. Because conductors hate magnetic changes, an opposite voltage appears which tries to keep electrons moving to to reinforce this magnetic field. But ultimately it exhausts itself. This results in a choke or inductor using its magnetic field to send its stored magnetic power down the line (like a capacitor) smoothing out voltage in the similar but opposite polarity of the situation discussed earlier. Now in a transformer with no secondary this power has nowhere to go, so it goes backwards back in into the circuit as 'reflection' of what it was just fed in nanoseconds earlier. This charge reflected back into the amp can wreak havoc with the tubes that now have to deal with this strange backwards power surge. That's why a shorted secondary (Fender speaker output jack shorted when not plugged in) is better than an open secondary (Marshall non shorted) from a reliability point of view.

vanhalen5150 wrote:Since [the Weber] speaker motors themselves have no magnet, how are they the same?

The resistance in the Weber motors comes simply from the resistance of a very long thin piece of copper wire. That's why they get so hot. What makes the motors better than a simple resistor is they have an inductance quality too (due to the fact they are built like an electromagnet or solonoid with a soft iron core [which focuses magnetic fields]) and because of their construction being very similar to a speaker, the inductance will also somewhat mimic that of a speaker. You could get similar mathematical results with a store bought inductor and resistor in series to duplicate the values but as we know here studying the old magical ways of amp making, nothing quite sounds like exactly duplicating physical structures and such.

So actual speakers are in fact inductors too, the magnetic field created in the coil of the speaker opposes/attracts the permanent magnet in the speaker and that causes the cone to move and create a very complicated reactive circuit that resistors or load boxes can't quite imitate.

Hope that made even a little bit of sense.

dirtycooter
Senior Member
Posts: 2923
Joined: Fri Oct 03, 2008 3:02 pm

Re: Multi Purpose Load Box and LineOut

Post by dirtycooter » Sat May 11, 2013 9:36 am

jnew wrote:Actually, now that I think about it, I'm not sure springs would work because I believe the speaker also has to move inwards. Not just a one direction movement of resistance but sort of out, in, and then returns to it zero position with resistance in both directions. :scratch:
Yeahbut
You CAN find a neutral point, affix the motor to the plate at that neutral position, and put springs on BOTH sides so it has resistance "to" and "from".
Whattya think of that shit??! :P :lol:

I have a good friend who owns a machine shop, could fabricate it pretty easy. How ever-I know jack shit about speakers really.
I mean I get the idea of what goes on-electricity goes in and makes the coil move magnetically, but after that I am retarded.
I would need to know how to get a speaker down to just the motor, then where to mount that motors point to the resistance plate.
Plus there would be measurements of resistance data I would have to know and then source correct stiffness of springs.
Would we be workin in "inch pounds"??? I think "foot pounds" would be far less accurate.

Post Reply