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Topic: Combiner box or A/B box question. FINAL OUTCOME |
George Kimery
From:
Limestone, TN, USA
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Posted 5 Nov 2018 7:14 am |
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I have an Evans amp and a Stereo Steel in my rack. I want to have one speaker cord for both amps going to my speaker cabinet. I am thinking about getting a project box and mounting three 1/4" jacks. Plug short speaker cords into two of the jacks and then one long speaker cord to my speaker cabinet out of the 3rd jack, in effect making a Y cord. I don't see why I would need an A/B box because I don't need to be switching back and forth while the amps are on. Only one amp will be on at a time. Am I making this way too comp!icated? Right now, I am running two speaker cords to the cabinet and have an 2 to 1 adapter plugged into the speaker jack. I would like to only have to run one cord to the cabinet, but it may not be worth the trouble and expense, unless somebody has a simple and better solution I will just stick with what I am doing. If they make a Y adapter with 3 jacks, I could use that at the amp, but I have never seen such an animal.
I just had another thought. What if I plug the two to one adapter into the speaker output of one amp, then run a short speaker cord from the speaker output of the other amp into the other other input of the adapter. Would the current from the 2nd amp speaker out manage to find its way through the adapter and on to the speaker cabinet without doing any damage to anything?
In an attempt to make this into a novel, I think I have just thought of the perfect solution, if I can find a pig tail long enough to reach both speaker outputs on each amp. I just need a Y adapter cord with two 1/4" male plugs on one end and a female plug on the other end. But this brings in the question of wire gauge and the use of a normal Y cord with current put out by a speaker cord. How about getting a couple of 1/4" plugs with short cords and twist and solder the ends of both cords together into one long speaker cord, thus making my own Y cord.
Last edited by George Kimery on 23 Dec 2018 10:09 pm; edited 1 time in total |
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Scott Duckworth
From:
Etowah, TN Western Foothills of the Smokies
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Posted 5 Nov 2018 12:18 pm
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Without the isolation provided by the A/B switch, you would be putting the power output of one amp into the other power amp, possibly letting all the magic smoke out... of one or both.
_________________
Amateur Radio Operator NA4IT (Extra)
http://www.qsl.net/na4it
I may, in fact, be nuts. However, I am screwed onto the right bolt... Jesus! |
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George Kimery
From:
Limestone, TN, USA
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Posted 5 Nov 2018 1:30 pm Combiner box or A/B box question.
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Scott, thanks for your reply, but I need to clarify something. Which scenario are you referring to? I am taking it you are referring to having an adapter into one amp, then jumping off another amp into the adapter.
To be safe, I will just run two speaker cords and unplug the cord from one amp before I plug the other cord in from the other amp. Do you see a problem using the two to one adapter on the speaker cabinet input and plugging both speaker cords into it? One amp is always going to be turned off. |
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Scott Duckworth
From:
Etowah, TN Western Foothills of the Smokies
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Posted 5 Nov 2018 3:36 pm
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As long as you remember to unplug the unused amp. Even with it turned off, it won't like the output of the other amp going into it's output.
A friend of mine did that same type of thing with two 100Watt ham radios. It's wasn't pretty.
_________________
Amateur Radio Operator NA4IT (Extra)
http://www.qsl.net/na4it
I may, in fact, be nuts. However, I am screwed onto the right bolt... Jesus! |
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Bill A. Moore
From:
Silver City, New Mexico, USA
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Posted 5 Nov 2018 3:49 pm
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Many amps now have "protection" diodes on the output, protecting the tubes/power transistors from the high voltage spikes that a speaker can generate. I can't imagine what voltage could be generated with one amps power output being stepped up with the other amps OT!
I think the only safe way to change amps to the same speaker is to have both off, and then plug the speaker into the one you want to use. |
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George Kimery
From:
Limestone, TN, USA
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Posted 5 Nov 2018 4:36 pm Combiner box or A/B box question.
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| I have a rack mount power strip that everything plugs into. I will just flip it off, killing power to everything. Then get up and change cords in the speaker cabinet. I was just hoping there would be a safe way to do it from my seat. |
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Tom Dillon
From:
La Mesa, California, USA
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Posted 5 Nov 2018 5:14 pm
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George, Here's a box that will do what you want. It's not just a simple passive AB box. There's some electronics inside and it's not cheap.
http://www.tonebone.com/tb-headbone-ss.htm
Last edited by Tom Dillon on 5 Nov 2018 6:16 pm; edited 1 time in total |
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George Kimery
From:
Limestone, TN, USA
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Posted 5 Nov 2018 6:06 pm Combiner box or A/B box question.
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Wow, but at a MSR of $325.00, off the planet. I will be using the Evans amp as my main amp. If I am happy with the sound I am getting in a room, then the Stereo Steel will not be used. If the Evans or Stuart power amp goes out, then it will be Stereo Steel to the rescue. So the chances are, I won't be changing amps except on rare occasions. I will have speaker cords going out of each amp to the speaker cabinet, and just keep the amp I am not using off and the speaker cord not connected.
I thought it would be nice during a show to switch in and out between the two amps in less than 5 seconds without having to get up and go to the speaker cabinet. |
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Godfrey Arthur
From:
3rd Rock
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Posted 6 Nov 2018 12:42 am
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If it's a "rare occasion" situation, it would be cheaper and safer if you just moved the speaker cable from one amp to the other (turning them both off first) if you don't want to splurge for a device that will do what you are asking.
There could also be a ground hum with two amps connected to one speaker with one on, one off coming out of the amp that is live or a ground fault to where a shock could happen.
AC and ground loops are mysterious at times.
Expect the unexpected.
Hence something like a Tonebone has things isolated and buffered, with relay switching not just a switch.
_________________
ShoBud The Pro 1
YES it's my REAL NAME!
Ezekiel 33:7
Last edited by Godfrey Arthur on 29 Nov 2018 11:43 am; edited 1 time in total |
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George Kimery
From:
Limestone, TN, USA
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Posted 29 Nov 2018 10:47 am Combine or AB box question
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I have been thinking about this and it has gotten way too complicated for what I want to do. Since using a simple Y cord at the speaker input or adding a 2nd speaker jack is a bad idea, there is no reason this won't work that I can think of, and it is as simple as you can get.
Make a box with two pair of jacks, one pair on each side of the box. Let's call them Stereo Steel pair and Evans pair. Put a switch on each pair. Connect a speaker cable from the Stereo Steel amp to the Stereo Steel pair then out to the speaker cabinet. The position of the on/off switch would determine if the signal would be allowed to pass. Run a 2nd speaker cable from the Evans amp to the Evans pair and then out to the speaker cabinet. Likewise, the position of the switch would determine if the signal would be allowed to pass. Both amps would never be on at the same time.
I now have two totally independent systems. I would have two speaker cables going to the amp, but I could safely use a Y adapter to plug them both into the speaker cabinet.
Does anybody know if I can buy a box like this already made up? I'm lazy. Something cheap.
I thought about just using in line switches on the cables, which is the simplest you can get, but it would be awkward getting to the cables without having to get up, plus it's not easy to tell when a line switch is on or off. |
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Tom Dillon
From:
La Mesa, California, USA
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Posted 29 Nov 2018 3:56 pm
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George, This guy make just about any routing box that can be made without active electronics:
https://www.loop-master.com/
I've bought a few boxes from him.
Be warned though: he takes a very long time to fill orders. Months.
I've used this box of his to switch 2 instruments between 2 amp inputs
https://www.loop-master.com/dual-instrument-tune-box153-with-outputs-p-345.html
I'm doing something similar to what you seem to be going for, but doing it differently. I had my Stereo Steel built with an extra Aux in where the tuner out usually is. That Aux is post EQ but pre FX. My original plan was to run my fiddle preamp into it and pick up the FX and use the SS amp and speakers. Lately, I run a Sarno V8 with a Solar Flare into it for a tube / distortion sound for slide guitar. The box above lets me switch two instruments into either preamp input ( SS or V8 ) while keeping the FX and amp settings the same. Works great.
_________________
Tom Dillon
- MSA Legend, On-Trak, fiddles, mandos |
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George Kimery
From:
Limestone, TN, USA
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Posted 30 Nov 2018 6:05 am Combiner box or A/B box question.
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OK, here is my latest hairbrained idea. Why not just use a simple AB switching box, except use it backwards. An
AB box is really just a Y cord with selectable switches. Just plug the speaker outputs of the Evans and Stereo Steel into the outputs of the AB box, and the speaker cable into the input of the box. Current will flow both both directions and doesn't know which way it is going. This idea makes things really simple. I just stomp on the A switch and the Evans signal only passes through. Stomp on the B switch, after turning the A switch off, and the Stereo Steel on!y passes through. This way, I only need one cable to go to the speaker cabinet. Is there any reason this won't work or is a bad idea? |
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Godfrey Arthur
From:
3rd Rock
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Posted 30 Nov 2018 6:31 am Re: Combiner box or A/B box question.
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| George Kimery wrote: |
| Is there any reason this won't work or is a bad idea? |
Might depend on the type switches used. Speaker switches need to be break before make varieties like DPDT and the grounds of both amps may not fare well being tied together.
I would ask the Loop-Master guy before getting all hared up.
_________________
ShoBud The Pro 1
YES it's my REAL NAME!
Ezekiel 33:7 |
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George Kimery
From:
Limestone, TN, USA
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Posted 30 Nov 2018 8:58 am Combiner box or A/B box question.
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Godfrey, I just sent an email to the looper guy to see if he can either make such a box or give me an opinion on using an AB box backwards. Maybe he will respond, maybe not.
Thanks for all your help. |
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Michael Maddex
From:
Northern New Mexico, USA
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Posted 30 Nov 2018 9:11 am
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George, consider this:
Parts:
1 - small Project Box
3 - 1/4¨ Jacks
1 - DPDT Center Off Toggle Switch
Hookup wire
Mount the Jacks and Switch in the Box
Two Jacks will be for your Amps and one for your Speaker
Looking at it from the bottom, Wire the Switch to the Jacks like this:
| Code: |
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to amp2 gnd | o o| to amp2 hot
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to spkr gnd | o o| to spkr hot
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to amp1 gnd | 0 0| to amp1 hot
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Mount the Box in a convenient place
Use your regular 1/4¨ Speaker Cables to connect the Box to the Amps and Speaker
FWIW, a box designed for switching instruments may not be able to safely handle the current required for the speakers
HTH. Good Luck. 
_________________
"For every expert, there is an equal and opposite expert." -- Arthur C. Clarke |
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George Kimery
From:
Limestone, TN, USA
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Posted 30 Nov 2018 11:25 am Combiner box or A/B box question.
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The Looper guy responded with a simple "I don't build that kind of box". End of story and dead end.
Michael, what you are describing is exactly what I had in mind. I can get DPDT switches at my local electrical supply that are built for electric motors and other electrical applications. They have them rated at 250 volts. Surely, these would handle any current put out by an amp through speaker wires.
Thank you for the wiring diagram. That I can use. |
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George Kimery
From:
Limestone, TN, USA
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Posted 20 Dec 2018 3:33 pm Combiner box or A/B box question. FINAL OUTCOME
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For the few of you that were following this subject and offered help, thank you. I bought all the stuff to make the A/B speaker cable box, but never made it. I found a better solution. While surfing the forum for information on Walker closed back cabinets, I stumbled onto Greg Cutshall's review of the Stereo Steel and cabinets. On a GD Walker link, it mentioned that with the proper cables (RCA to 1/4" phono) you could use the RCA inputs on the back of the Stereo Steel to drive a separate pre-amp. I knew these inputs were there, but since they were primarily designed for a CD player, I never thought pre-amp. BINGO! problem solved. The beauty of it is I had a 4 space rack case with the Stereo Steel combo and Rack Rider power strip. This left one space left for the Evans pre-amp. So I have a great set-up up that doesn't weigh much and is not very big to sluff around. I no longer need a separate power amp for the Evans. I can switch from one amp to the other by just moving the input cable from my Wet Reverb. Also running a Black Box and Lehle Volume pedal. Both the Stereo Steel and Evans are awesome amps. I think my amp buying days are over.
(Well,there is that Dr.Z Surgical Steel head I would love to try) |
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