Hi guys

Bit of a weird question, but here we go.

I'm looking to make a device for inside of an iso cab, which can move a mic stand left and right over a distance of about 7 inches to cover the centre to outer cone of a speaker. I would like it to be push button controlled, so that I could move it a 1/4 inch left or right over a distance of around 7 inches. Here's a terrible diagram I've just made up:



There is a company that builds one that looks like a windscreen wiper:

http://www.youtube.com/watch?v=VPtYM3treFA

I was looking at making a camera slider like this:



But I would need a way of motorizing it, and the only thing I could think of was a small DC motor with a dolly system.

Any ideas on a better way to do this?

Cheers for any ideas you can give me,

Here's a video of a mechanical camera slider in action:

web page

How about using a micro controller like PICaxe or Arduino to control a stepper motor of some sort. A standard DC motor is harder to control to the degree you require whereas a stepper motor is very controllable.

You can try a stepper motor to power a loop of wire/string backwards and forwards. You can find stepper motors with a threaded shaft that moves backwards and forwards. And you can search for Linear Actuators which might also do the job.

All three would be capable of moving your mic backwards and forwards along the track. You can add limit switches to stop it going too far in either direction and a reset function. And should be easy to have a couple of buttons for left/right movement and maybe even a display that tells you in inches/cm how far you have moved the mic.

A few minutes thought comes up with loads of other ways you could do get a stepper motor to drive the dolly, how about having the dolly run up and down a threaded rod turned by the motor?

Hope that helps

Andy

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When the going gets weird, the Weird turn Pro.

The difficulty inside an isocab will be space I guess. I know Eric Valentine made something like this. I think it's mentioned in his SOS interview.

J

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www.jackruston.com

Yep, steppers are the way to go, but I would probably not bother with the linear slide rail (expensive).

How about reusing the guts of an old dot matrix printer? The carriage should be quite well suited to butchering to take a mic clip and the simple round bar guide rails and toothed belt will be quite man enough for the job.

Tiny micro, some microswitches and a not very butch driver chip and the job is a good one.

Regards, Dan.

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Audiophiles use phono leads because they are unbalanced people!

Low tech solution.

Slide rail. Hang it from some curtain track. Drive it via a length of studding (6mm gives you exactly 1mm movement for one rev, just need a counter!). Note you would need to buy a split 6mm die* and run the studding thru it to clean up the threads and make it run smoothly. There will be some backlash but we are not talking "Vorsprung..." here are we?

S or bust limit microswitches each end and you could have micro switches at intervals to light external LEDs but! Cameras are so cheap these days. Fit one and an LED floodlight and a graduated scale inside the box.

*Or saw 1/2 way thru a 6mm nut and squeeze it!

Dave.

Quote ef37a:

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Low tech solution.

Slide rail. Hang it from some curtain track. Drive it via a length of studding (6mm gives you exactly 1mm movement for one rev, just need a counter!). Note you would need to buy a split 6mm die* and run the studding thru it to clean up the threads and make it run smoothly. There will be some backlash but we are not talking "Vorsprung..." here are we?

S or bust limit microswitches each end and you could have micro switches at intervals to light external LEDs but! Cameras are so cheap these days. Fit one and an LED floodlight and a graduated scale inside the box.

*Or saw 1/2 way thru a 6mm nut and squeeze it!

Dave.

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Spoil Sport !!

LOL

Good News, Bad News. This afternoon I discovered that my Epson R200 has finally popped it's clogs, that was the bad news. The good news is that my brother has an old R200 that has hardly been used that I can 'commandeer' to take it's place for a few more years. And while examining my dead R200 I spotted a very nice NEMA stepper motor I can salvage for experiments

Andy

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When the going gets weird, the Weird turn Pro.

One acronym Andy...K.I.S.S. Bloody computers! Like Jezzer said, " Put a CPU in an assult rifle and we stop all war"!

My Brother MFC-7420 is playing silly buggers. Won't pick paper from the bottom tray or if it does it jams on the second sheet. I have replaced toner and drum and blasted it with a can of air but no joy. Will have to find a decent printer tech'.

Dave.

Cheers for all the replys guys! I'm busy looking through and trying to get get my novice head around your ideas! I should specify that the inside dimension of the iso will be around 20 inches, but the the mic only needs to be able to travel around 7 inches to cover the centre to speaker to outer edge.

Quote dmills:

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Yep, steppers are the way to go, but I would probably not bother with the linear slide rail (expensive).

How about reusing the guts of an old dot matrix printer? The carriage should be quite well suited to butchering to take a mic clip and the simple round bar guide rails and toothed belt will be quite man enough for the job.

Tiny micro, some microswitches and a not very butch driver chip and the job is a good one.

Regards, Dan.

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Anymore details on Tiny micro, some microswitches and a not very butch driver chip What, where to buy, how to setup?

Cheers

Kieran

http://www.bizoner.com/pan-and-tilt-kit-with-hitec-hs311-servos-for-sensor -mount-p-223.html?zenid=qjs9ldoop821dkqa6isgmfrg82 ?

You only need "pan" and the mic describes a very shallow arc but 'tis only rock and roll!

Dave.

Kieran...

Do you have any experience with micro-controllers or hobby robots/remote control cars/boats/planes? Or are you starting from scratch?

And are you in the UK, Europe, or USA? No point in recommending suppliers on the wrong continent.

Andy

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When the going gets weird, the Weird turn Pro.

Quote zenguitar:

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Kieran...

Do you have any experience with micro-controllers or hobby robots/remote control cars/boats/planes? Or are you starting from scratch?

And are you in the UK, Europe, or USA? No point in recommending suppliers on the wrong continent.

Andy

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Yeah! If I had my way I would make it a condition of membership of any forum to tell us where you are to the nearest 100 clicks!

Dave NORTHAMPTON NN5 5** !!!

Quote zenguitar:

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Kieran...

Do you have any experience with micro-controllers or hobby robots/remote control cars/boats/planes? Or are you starting from scratch?

And are you in the UK, Europe, or USA? No point in recommending suppliers on the wrong continent.

Andy

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Total novice I'm afraid!

I'm based in Hampshire, south of England.

Loved the idea about butchering an old printer, just need to understand how to control the movement in 1/4 inch steps.

OK Keiran,

You have a couple of learning curves ahead if you want to proceed with your plan. The first is to build the mechanism to move the mic. The second is to build a device to power it and control it's movements so that they are accurate enough for you and repeatable. Although the idea is quite simple, it will be quite challenging to make it work effectively and reliably enough to make it worth while. If you keep having to open the iso-box because it isn't working properly you might as well just put in an access hatch, fit the mike on a gooseneck, and adjust it by hand.

The simplest mechanism would be a simple pan head operated by a servo. Select the correct angle of rotation and you could get that 7" range of movement. However, in the extreme positions the sound will be coming at the side of the mic which might be a problem. The device Dave linked to would do the job but is more complicated (and more expensive) than you need. You could knock up something with a door hinge and a basic servo. A slider would be more accurate, but breaking up an old printer isn't for the faint hearted. How you do it depends on what printer you have, and you will have to work out yourself how to make it work.

To make it all work you'll then need to choose your micro-processor, get one, learn how to program it, and work out how to interface it with your stepper motor or servo. There are a few options out there, but the main candidates would be a PICaxe or an Arduino. Both have their advocates and there is plenty of info online about both of them. However, for a beginner the Arduino has a lot to commend it. It was designed for beginners but is capable of some very powerful things in the right hands. It is open source, so there are a lot of companies making compatible devices and you can even make your own from kits or even from parts. Most people start with an Arduino Uno which you can get here, here, or here. All of those are very good suppliers, and they also sell things like expansion boards for motor controllers, servos, stepper motors, robotics parts and so on.

I would suggest you spend some time reading the Arduino site and doing a little research there before you go any further. There are plenty of examples of what people have already achieved.

Andy

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When the going gets weird, the Weird turn Pro.

What is your budget?

A fairly elegant solution is something like This
It is a stepper motor with built-in linear actuator. You only need to add a 'home' limit switch to be able to get repeatable and accurate results. Although the stroke length is only about 2 inches, you can either use a longer lead screw, or attach it part way along a lever, with the mic on the end.

Proper dedicated drives will set you back about £150, but as these are nice low voltage, low current devices, Andy's suggestion, a cheaper (and more interesting) option, is to go the Arduino route. There are articles on their home page about stepper driving.

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It wasn't me!
(Well, actually, it probably was)

You might consider applying your ingenuity instead to a method of getting a simple mechanical control rod through the wall of the box. I think you'd spend less time mending this solution!

Heh, love this "mic-robotomy" stuff. Reminds me of my early studio days, where the studio couldn't afford the remotely controlled electro-mech damper adjustment option for the EMT plate and we had to settle for the basic manual handwheel, and then used to brainstorm endlessly on how to fit a motor of some sort and remotely control it. Got very Rube Golderg-esque (Heath Robinson-esque) at times. To this day I still think the hamster in a wheel idea had merit.

I mean, really, much more practical than that ridiculous donkey-carrot proposal.

Maybe time to hunt down that old Meccano (Erector) set gathering dust in the attic...

Quote Folderol:

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What is your budget?

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Not big I'm afraid.

I was looking to build the iso cab for around £150-£200. Its going to be a box within a box design, made with 3/4 inch mdf and filled with rockwool. I have most of the rockwool and acoustic foam, just need to get the mdf cut to size when i'm ready to build.

Funnily enough the "Rod through the box idea" was the first thing my Dad came up with when I mentioned the idea to him. This would be easier, but wouldn't drilling holes through the box compromise the isolation?

Quote Kizzer:

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Funnily enough the "Rod through the box idea" was the first thing my Dad came up with when I mentioned the idea to him. This would be easier, but wouldn't drilling holes through the box compromise the isolation?

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You're not going to get perfect isolation anyway. If that's what you're after, put the whole thing in a distant room (in which case, why bother with the enclosure?).

Ships manage to feed a propellor shaft through the hull. Drive shafts get in and out of gear boxes without an oil leak. You should be able to make a gland for a control rod.

Its not going to be silent, but with the box within a box idea I will achieve between a 35-40db decrease in sound level. I have neighbours next door and my recording is limited to nights due to work and travel commitments, so needed to find a way of recording at resonable levels without disturbing people.

Being able to set the mic on the centre of the speaker and move it in 1/4 inch steps to the outer edge of the speaker, while being able to listen to the results in real time over the monitors would be yet another way to use my time more effectively. The only other method would be going to the iso, opening two lids, resetting the mic position, shutting both lids and returning to listen to the results. I'm just trying to make the most of what time I have.

A fairly elegant solution is something like This
It is a stepper motor with built-in linear actuator.

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That looks great! When you say stroke length, do you mean it will only move 2 inches, or that the length of the rod that moves is only 2 inches?

Just found this:

http://www.youtube.com/watch?v=uewMphsBamk&feature=fvwrel

Something like this would be great!

Quote Kizzer:

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Just found this:

http://www.youtube.com/watch?v=uewMphsBamk&feature=fvwrel

Something like this would be great!

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And about $770 (£490) which is more than twice your entire budget. However, it is essentially a stepper motor driving a lead screw which is something I mentioned earlier. You could make something similar with a couple of drawer slides, a stepper motor, and a long screw.

Andy

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When the going gets weird, the Weird turn Pro.

Yeah, the price is too high. But it was along the same lines as my original idea. I like your idea! Would it be controlled in the same way with Arduino?

Quote Exalted Wombat:

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Quote Kizzer:

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Funnily enough the "Rod through the box idea" was the first thing my Dad came up with when I mentioned the idea to him. This would be easier, but wouldn't drilling holes through the box compromise the isolation?

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You're not going to get perfect isolation anyway. If that's what you're after, put the whole thing in a distant room (in which case, why bother with the enclosure?).

Ships manage to feed a propellor shaft through the hull. Drive shafts get in and out of gear boxes without an oil leak. You should be able to make a gland for a control rod.

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Yes, get a cable gland from Maplin and grease the inner cable grip with silicone grease then nip it up on the shaft to get the right seal but with motion.

Dave.

Maybe no need for any holes (except for passing the cables of course, which could be easily sealed airtight with a bit of silicone sealant).

How about using a pair of magnets, one at the upper inside of the inner box, fixed to an adjuster rod carried in a couple of blocks fixed to the inner top and suspending the mic below, and one positioned above it on the top of the outside box to move the inside one about?

Suddenly guitar rig plugins seem so much easier!

H

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Technical Editor, Sound On Sound

Quote Hugh Robjohns:

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Suddenly guitar rig plugins seem so much easier!

H

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HA HA! Exactly!

Quote Kizzer:

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Its not going to be silent, but with the box within a box idea I will achieve between a 35-40db decrease in sound level. I have neighbours next door and my recording is limited to nights due to work and travel commitments, so needed to find a way of recording at resonable levels without disturbing people.

Being able to set the mic on the centre of the speaker and move it in 1/4 inch steps to the outer edge of the speaker, while being able to listen to the results in real time over the monitors would be yet another way to use my time more effectively. The only other method would be going to the iso, opening two lids, resetting the mic position, shutting both lids and returning to listen to the results. I'm just trying to make the most of what time I have.

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Use the time you would have spent fitting up this complicated (and, I suspect, unreliable) mechanism in making some test recordings with the mic in different positions. Then you'll know where it needs to be for the sound you want. Also, design some quick-release catches for the lids!

I've got a sneaky feeling that DI, maybe through some speaker emulation, is likely to sound better than a boxed-in cabinet.

Quote zenguitar:

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You could make something similar with a couple of drawer slides, a stepper motor, and a long screw.

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A couple of drawer slides and a bit of string would be fine for me.

I'll happily have a long screw as well, although I don't know how it would help with the project.

Or!
Two mics, one centred, one on the outer edge and pan them?
I am sure the acoustics of a small box screws this up quite a lot but if you have a couple of '57s say, it would take but an evenings work to try it.

In any event you could have the choice of two different "takes" if you panned hard left and right.

Dave.

Quote grab:

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Quote zenguitar:

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You could make something similar with a couple of drawer slides, a stepper motor, and a long screw.

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A couple of drawer slides and a bit of string would be fine for me.

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Some people just have no soul

Quote:

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I'll happily have a long screw as well, although I don't know how it would help with the project.

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Just make sure you don't end up with a cross head.

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It wasn't me!
(Well, actually, it probably was)

Quote Folderol:

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Just make sure you don't end up with a cross head.

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It's never a problem when you strip the threads initially, just when you need to get it out again. And of course there's always too much torque.

OK, I'll stop now.

Quote grab:

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Quote Folderol:

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Just make sure you don't end up with a cross head.

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It's never a problem when you strip the threads initially, just when you need to get it out again. And of course there's always too much torque.

OK, I'll stop now.

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Good to hear

Just found this:

http://www.youtube.com/watch?v=DLXWtqxn5wA

I guess this is the same idea with the linear actuator. Looks like an ideal way of doing it.

Even better!

http://www.firgelliauto.com/product_info.php?cPath=104&products_id=108

This would be great! Now to find one in the UK!

http://www.youtube.com/watch?v=Br6wyrU-IT8

OK.... It's always fun to look at those commercial products. They are always tempting too, but better to think of them as Inspiring.

$200.

Plus shipping, plus Duty, plus VAT.

And 400lbs of force!!! A little over-specified I think.

Google for 'Reprap' which is an open source 3D printer/CNC machine. There is an entire community of people out there devoted to making similar devices with home made slides and stepper motors. They make these things accurate to a fraction of a mm using simple drawer slides.

Time to get down to some serious research rather than wishful thinking methinks.

Andy

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When the going gets weird, the Weird turn Pro.

Time to get a DI box and get on with some music-making as well!

Quote Exalted Wombat:

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Time to get a DI box and get on with some music-making as well!

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Got a DI coming

Quote Kizzer:

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Quote Exalted Wombat:

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Time to get a DI box and get on with some music-making as well!

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Got a DI coming

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Here's the DI I really like using (btw, when used as an amp modeler it has switchable mic positions - no iso box required):

http://www.soundonsound.com/sos/nov10/articles/palmer-pocketAmp.htm

(no hamsters required either!)