building an A/B speaker switch - would appreciate input

JMB · 9th June 2006, 01:09 PM

I am designing and planning to build an A/B speaker selection switch box. I want to put volume controls on each speaker selector so I can compare pairs of speakers at equal volumes. Can I just use an adjustable L-pad or does it require a volume control like the wall mount type units? I assume that things like a volume control (Radio Shack 271-1732 for example) are line level and not speaker level controls.

Any guidance would be appreciated.

Also, if anyone has done something like this, I would love your input, feedback, and even examples of what you have done.

Thanks,

Jay

sreten · 9th June 2006, 01:40 PM

Hi,

you cannot use L-pads to equalise volumes as they seriously
compromise the source impedance seen by the speaker and
generally will the turn the bass end into mush.

The simplest / cheapest way of switching is a dual gang lightswitch
in a box, the negative is common and the switches select the speaker.

/sreten.

JMB · 9th June 2006, 04:56 PM

Any idea how the wall unit volume controls such as Partsexpress 300-546 or 300-548 are put together? They are speaker level volume controls?

Thanks,

and thanks for the input thus far,

Jay

sreten · 12th June 2006, 09:53 AM

Hi,

a proper volume control would need tapped transformers which the Dayton parts appear to have :

Bass power handling will not be good though, accurate a/b comparisons will not be possible.

/sreten.

rpapps · 12th June 2006, 10:13 AM

Quote:
"The simplest / cheapest way of switching is a dual gang lightswitch
in a box, the negative is common and the switches select the speaker." /Qoute

Since amplifier is not specified, have to consider it might be bridge configuration so double pole switching is recommended.

Switchable volume controls at amp input would be simplest way to match levels.

Cheers
Rob

sreten · 12th June 2006, 04:35 PM

Quote:

Originally posted by rpapps
Quote:
"The simplest / cheapest way of switching is a dual gang lightswitch
in a box, the negative is common and the switches select the speaker." /Quote

Since amplifier is not specified, have to consider it might be
bridge configuration so double pole switching is recommended.

Rob

Hi,

The dual gang lightswitch will work perfectly well with a bridged amplifier.

In the above case negative is not also earth, but its still negative.

/sreten.

bluesmoke · 16th June 2006, 11:26 AM

Wow, never would have even thought of the lightswitch idea...

Just built my own A/B switchbox a short while ago. Used a decently affordable DPDT toggle that I was satisfied that it had a solid and very strong 'SNAP' when making contact (mechanically). Used a strong plastic enclosure (good for electrical isolation, if placed on or near your equipment; no chance to short to earth), but will probably rebuild into a nicer enclosure when I have time and can afford it. I cheaped out and didn't invest in gold plated posts at the time... a big (mostly aesthetic) regret that would have been easy to avoid. Still haunts me.

Like everyone is saying, volume pads in the speaker section are not a great idea.

9th June 2006, 01:09 PM	#1
JMB diyAudio Member Join Date: Apr 2004 Location: Texas	building an A/B speaker switch - would appreciate input I am designing and planning to build an A/B speaker selection switch box. I want to put volume controls on each speaker selector so I can compare pairs of speakers at equal volumes. Can I just use an adjustable L-pad or does it require a volume control like the wall mount type units? I assume that things like a volume control (Radio Shack 271-1732 for example) are line level and not speaker level controls. Any guidance would be appreciated. Also, if anyone has done something like this, I would love your input, feedback, and even examples of what you have done. Thanks, Jay

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9th June 2006, 01:40 PM	#2
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, you cannot use L-pads to equalise volumes as they seriously compromise the source impedance seen by the speaker and generally will the turn the bass end into mush. The simplest / cheapest way of switching is a dual gang lightswitch in a box, the negative is common and the switches select the speaker. /sreten.

9th June 2006, 04:56 PM	#3
JMB diyAudio Member Join Date: Apr 2004 Location: Texas	Any idea how the wall unit volume controls such as Partsexpress 300-546 or 300-548 are put together? They are speaker level volume controls? Thanks, and thanks for the input thus far, Jay

12th June 2006, 09:53 AM	#4
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, a proper volume control would need tapped transformers which the Dayton parts appear to have : Bass power handling will not be good though, accurate a/b comparisons will not be possible. /sreten.

12th June 2006, 10:13 AM	#5
rpapps diyAudio Member Join Date: Jul 2004 Location: nowhere of interest	Quote: "The simplest / cheapest way of switching is a dual gang lightswitch in a box, the negative is common and the switches select the speaker." /Qoute Since amplifier is not specified, have to consider it might be bridge configuration so double pole switching is recommended. Switchable volume controls at amp input would be simplest way to match levels. Cheers Rob

16th June 2006, 11:26 AM	#7
bluesmoke diyAudio Member Join Date: Mar 2006 Location: Great White North	Wow, never would have even thought of the lightswitch idea... Just built my own A/B switchbox a short while ago. Used a decently affordable DPDT toggle that I was satisfied that it had a solid and very strong 'SNAP' when making contact (mechanically). Used a strong plastic enclosure (good for electrical isolation, if placed on or near your equipment; no chance to short to earth), but will probably rebuild into a nicer enclosure when I have time and can afford it. I cheaped out and didn't invest in gold plated posts at the time... a big (mostly aesthetic) regret that would have been easy to avoid. Still haunts me. Like everyone is saying, volume pads in the speaker section are not a great idea.

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