TornadoTed

Guitar Speaker Switcher
« on: May 13, 2010, 03:54:06 PM »
I would like to know how I could go about building something that does the same thing as the Radial Cab-Bone

http://www.tonebone.com/tb-cabbone.htm

But with 4 outputs so I can connect 4 cabs to one valve amp and not damage it by having a constant load.

I really am a utter novice so nothing overly technical please  ;)
Giant Wafer Studios

www.giantwafer.com


Re: Guitar Speaker Switcher
« Reply #1 on: May 13, 2010, 04:38:49 PM »
To be able to switch between 4 different cabs ( I assume this is what you wish to do ) you will need

at least a double-pole 4 position switch(DP4T).  Assuming you want this for mounting in a box for foot

switching this rules out rotary, slide, or toggle type switches.  Heavy duty pushbutton switches in a

DP4T configuration aren't very common - I could not pull one up with a routine search.  Someone may

have them.  The type needed for switching between 2 cabs can be found here:

https://taweber.powweb.com/store/sword.htm     item #  WSW-DPDT-PB


Likely no one has made a box for switching between 4 cabs because of common usage - open back vs closed back or 10in spk vs 12 or 15in.

I applaud your choice to build your own box - why spend $450.00 when you can do it for $15.00  ;)

Arno

Re: Guitar Speaker Switcher
« Reply #2 on: May 13, 2010, 05:18:46 PM »
I assume you don't want to combine several cabs at the same time but just run through them for multiple sound variations?
I'm not sure you want it in a footswitch?
You'd have to make several combinations with 3 switches and that would be very complicated to use.

4 position 2 pole rotary switch looks easiest. Search for lorlin for cheap or grayhill, elma for expensive!

Or you could make a logic circuit + relays to toggle through different cab outputs with a footswitch  ;D

isophase

"we'll fix it in the shrinkwrap" fz

Re: Guitar Speaker Switcher
« Reply #4 on: May 13, 2010, 06:09:46 PM »
this ???
http://www.musikding.de/product_info.php/info/p1193_4PDT-footswitch.html


Nice find - that would be the one.  

EDIT:  Correction - misread as DP4T.  That will not work, and as Colin pointed out that is mechanically difficult to do in a stomp switch.
« Last Edit: May 13, 2010, 07:26:13 PM by lassoharp »

TornadoTed

Re: Guitar Speaker Switcher
« Reply #5 on: May 13, 2010, 06:11:44 PM »
Thanks for the all the info.

Yes I'd like to switch between 4 cabs with Vintage 30s, G12Hs, Greenbacks or Alnico Blues. I do it now by using a speaker patchbay but it's a pain having to switch off the amp everytime I switch cab.

I ideally wanted to build it into a 1u 19" rack case.

Is the power involved going to be a problem, 100w maybe more with my bass amp?
Giant Wafer Studios

www.giantwafer.com

ColinS

Re: Guitar Speaker Switcher
« Reply #6 on: May 13, 2010, 06:55:12 PM »
this ???
http://www.musikding.de/product_info.php/info/p1193_4PDT-footswitch.html


Nice find - that would be the one. 

No...I don't think it is. Thats 4 poles with two positions. I can't imagine how a 2 pole 4 position switch would work in button form.

I'd go with a box full of relays and logic switching. I don't imagine it can be that complicated. Power handling isn't a problem if you go down that route either. Just buy bigger relays!

C
Blue LEDs make the world go round

Re: Guitar Speaker Switcher
« Reply #7 on: May 13, 2010, 07:39:50 PM »
this ???
http://www.musikding.de/product_info.php/info/p1193_4PDT-footswitch.html


Nice find - that would be the one. 

No...I don't think it is. Thats 4 poles with two positions. I can't imagine how a 2 pole 4 position switch would work in button form.

I'd go with a box full of relays and logic switching. I don't imagine it can be that complicated. Power handling isn't a problem if you go down that route either. Just buy bigger relays!

C


Thanks for spotting the misread - post edited.

You can certainly use relays though it's a more involved build.  If footswitching isn't mandatory a rotary switch in a metal box should do the job.

Denyle Guitars

Re: Guitar Speaker Switcher
« Reply #8 on: May 13, 2010, 09:03:14 PM »
I have an Ampeg 8x8 amp switcher which is nothing more than two rotary switches and a few big load resistors.

PRR

Re: Guitar Speaker Switcher
« Reply #9 on: May 13, 2010, 10:32:43 PM »
Assuming snap-action switches (toggles or relays), and all outputs loaded, this switching topology (below) will keep a load on the amp at all times. Mid-way through a switch event the load may be two speakers in series; this will generally be enough to keep an OVER-driven tube amp from punching-out its transformer insulation. Most toggles and relays will clack-over in 1/100th of a second, so the "high load" time is very short.

If a speaker is disconnected, throwing to that non-load will of course leave the amp unloaded.

For 15Watt cathode-bias amps, you may use shorting jacks so that a no-plug will short the non-load; the amp will be fine. However HIGH-power fix-bias amps generally will NOT like a dead short. And you are not protected from some fool plugging one end of the cable and not the other (I have been that fool).

The "danger" is only when the amp is playing LOUD. If you take the amp down "silent" (faint hiss/hum OK), you may unload it without harm. Of course the risk is that some sound will pass through while you have it unloaded. I do it all the time on test-bench with meter/'scope; but on a chaotic stage, betting that "NO!" signal will happen may be risky.
« Last Edit: May 13, 2010, 10:35:50 PM by PRR »


TornadoTed

Re: Guitar Speaker Switcher
« Reply #10 on: May 14, 2010, 05:10:47 AM »
Thanks for the drawing and explanation PRR.

It's for studio use, I like tracking guitars with the head in the control room and the cabs out in the live room. My plan is to have the 4 cabs with one darker mic and one brighter mic on each cab. If one of those 8 tonal variations doesn't work then I fear there is something badly wrong with the part  ;D
Giant Wafer Studios

www.giantwafer.com

Re: Guitar Speaker Switcher
« Reply #11 on: May 14, 2010, 08:19:25 AM »
I want to get me one of them 12x4 cabinets!

Gus

Re: Guitar Speaker Switcher
« Reply #12 on: May 14, 2010, 12:35:10 PM »
You might want to find the largest value resistive load the amp will be stable into and have that always across the transformer output.


Re: Guitar Speaker Switcher
« Reply #13 on: May 14, 2010, 01:54:52 PM »
I'm not sure if this was specifically stated:  Consider switching jacks on the output that switch in 100W load resistors when the speaker is unplugged.  This way if you are only running 3 cabinets (because you lent me that cool 12x4 that PRR sold you) and accidentally switch on speaker 4, your head doesn't release any magic smoke.

PRR

Re: Guitar Speaker Switcher
« Reply #14 on: May 14, 2010, 11:49:21 PM »
> I want to get me one of them 12x4 cabinets!

Or new PC glasses?

It's a Sweet Sixteen. A reaction to the one-15" boxes of the 1950s. 16 of Quam's less-nasty 4" communication speakers makes, ummmm, an "interesting" array. The thin bass of a single stiff 4" is boosted by coupling. The pencil-tight highs-beaming of a 15" is broken-up by multiple unmatched cones, each of which can work higher than most 15"s. And back then you could buy a crate of fine small Quams for not much money.

Actually the plan was 5" speakers from Sonotone.
http://www.roger-russell.com/columns/columns.htm#sweet
« Last Edit: May 14, 2010, 11:55:37 PM by PRR »

Re: Guitar Speaker Switcher
« Reply #15 on: May 15, 2010, 09:38:02 AM »
>>>Or new PC glasses?

LOL!  Wow, I have no  excuse for that flub.  Back to sesame street for me.  I still want one though.

I remember seeing a picture of Stanley Clarke form the late 70s or early 80s where he was playing out of a giant sphere covered in ~2-4 inch speakers.  I couldn't find it on the web though.
« Last Edit: May 15, 2010, 11:52:11 AM by Emperor Tomato Ketchup »

Re: Guitar Speaker Switcher
« Reply #16 on: May 15, 2010, 12:35:50 PM »
>>>Or new PC glasses?

LOL!  Wow, I have no  excuse for that flub.  Back to sesame street for me.  I still want one though.

I remember seeing a picture of Stanley Clarke form the late 70s or early 80s where he was playing out of a giant sphere covered in ~2-4 inch speakers.  I couldn't find it on the web though.


Oh Yeah - that's a cool one. A nice pic of that alien looking rig can be found in The Guitar Handbook by Ralph Denver p200.  Says it uses 24 4.5in speakers mounted in a plexiglass dome.

PRR

Re: Guitar Speaker Switcher
« Reply #17 on: May 16, 2010, 12:45:27 AM »
> a giant sphere covered in ~2-4 inch speakers.

There was a design floated in the late 1960s. Decades of chemicals have rotted my memory..... I need help on details.

I think there was a mention in The Whole Earth Catalog.

I think(??) that was sourced from a book about appropriate technology. The name "pasternik" is in my mind but clearly wrong. The book covered adobe housing, wood water pumps, dung-fired thermocouple radios, and other technologies appropriate in low-tech places (Africa, India, also the counter-culture).

The speaker: cut a cardboard pentagon. Mount a speaker. Fold the edges up. Do this dozens of times. Staple the edges together to form a sorta-sphere. Claims: omni-directional, stiff, low cost, horn-coupled, high performance.

> a plexiglass dome.

Obviously a good plastics-crafter with excess time can bend-up anything you can do in cardboard. And I do recall something like that (or is that the chemicals?). Likewise some wood, a tilt tablesaw, and glue can form hedra.

The convex regular polyhedra seem to stop at 20 faces (10 for a hemi), but Bucky's (and Bauersfeld's) geodesics run to approximately any number of faces.

sodderboy

Re: Guitar Speaker Switcher
« Reply #18 on: May 16, 2010, 08:53:30 AM »
Since it's for a semi-controlled studio environment, couldn't you have one side of each cab connected as a common and have a single switch trigger "H" through a series of D flipflops, each output driving a beefy SPST relay, each relay with a large cap to time-out with a delay when disconnected?  It powers-up with A connected, and you make A active low so that A is always connected with the power off.  That would stay close the original two way product, and require very little in the way of components.  On the controller, which could be a small remote box, would be one momentary foot switch and 4 LED's.
I usually like passive, but this is barely active.
Now it's time for the PIC'sters to chime-in, because, it could be done very simply but elegantly that way. . .
Mike
PS: that makes for a lot of speaker tie-lines out to the studio.


 

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