RA Switch

[Uncle Sammy]

I use an rca-type switchbox to link mac, tv and external speakers. This causes a hum. An isolation transformer between TV (or computer or both) and switch ends the hum but kills one of the two audio channels. Sometimes the working audio channel changes from L to R or reverse. Sometime both audio channels work on TV but not mac or the reverse. The bug is unstable. Ive done many tests and substitutions, including more expensive switches. All fail to cause no hum and both audio channels on mac and TV. A techie said that the hum is caused by the tv's ground being unbalanced relative to the mac's ground. He advised a better switch. All switches Ive tried, from $5 to $25, have the bug. Is the switch the problem? If so, how expensive is a proper switch? If so, how can I know what is a proper switch? Please advise.

 

[slipperybidness]

I use an rca-type switchbox to link mac, tv and external speakers. This causes a hum. An isolation transformer between TV (or computer or both) and switch ends the hum but kills one of the two audio channels. Sometimes the working audio channel changes from L to R or reverse. Sometime both audio channels work on TV but not mac or the reverse. The bug is unstable. Ive done many tests and substitutions, including more expensive switches. All fail to cause no hum and both audio channels on mac and TV. A techie said that the hum is caused by the tv's ground being unbalanced relative to the mac's ground. He advised a better switch. All switches Ive tried, from $5 to $25, have the bug. Is the switch the problem? If so, how expensive is a proper switch? If so, how can I know what is a proper switch? Please advise.

How about figuring out a solution that omits the "switch" completely?

Honestly, we don't have enough info provided to give you meaningful advice here. Why do you "need" this switch?

Do you have a cable box and/or a coax cable connection (from a provider) in your system? The first step should be to disconnect that coax and see if the hum goes away. Cable Company coax cables are notorious for introducing a poor ground into your system!

 

[Uncle Sammy]

The switch allows easy switching between external speakers and TV or Mac.

Disconnecting coax ended hum but, of course ,now I have no TV reception. It also returned the missing Mac audio channel and stopped the one TV audio channel. TV sound now fails completely even with only internal speakers.

 

[Eppie]

Your original post is lacking in some details. Are these powered speakers (built-in amps) and if not how are you driving the speakers? Are the TV and mac acting as audio sources? Maybe a photo of the switch box connections or a link to the model of switch box that you're using. Is the isolation transformer on the power connections or along the inputs and how is it connected? The more details you can provide the better.

 

[Uncle Sammy]

Your original post is lacking in some details. Are these powered speakers (built-in amps) and if not how are you driving the speakers? Are the TV and mac acting as audio sources? Maybe a photo of the switch box connections or a link to the model of switch box that you're using. Is the isolation transformer on the power connections or along the inputs and how is it connected? The more details you can provide the better.

Your original post is lacking in some details. Are these powered speakers (built-in amps) and if not how are you driving the speakers? Are the TV and mac acting as audio sources? Maybe a photo of the switch box connections or a link to the model of switch box that you're using. Is the isolation transformer on the power connections or along the inputs and how is it connected? The more details you can provide the better.

Powered speakers, w/TV and Mac as audio sources. Switch box photo included. Isolation transformer between TV and

Your original post is lacking in some details. Are these powered speakers (built-in amps) and if not how are you driving the speakers? Are the TV and mac acting as audio sources? Maybe a photo of the switch box connections or a link to the model of switch box that you're using. Is the isolation transformer on the power connections or along the inputs and how is it connected? The more details you can provide the better.

Powered speakers w/TV, Mac as audio sources. Photo included. Isolation transformer between TV and RCA switch. I cannot think of more relevant details.

 

[Uncle Sammy]

Powered speakers w/TV, Mac as audio sources. Photo included. Isolation transformer between TV and RCA switch. I cannot think of more relevant details.

 

[Uncle Sammy]

Powered speakers w/TV, Mac as audio sources. Photo included. Isolation transformer between TV and RCA switch. I cannot think of more relevant details.

 

[Uncle Sammy]

your sites "post" broken

 

[Uncle Sammy]

Your original post is lacking in some details. Are these powered speakers (built-in amps) and if not how are you driving the speakers? Are the TV and mac acting as audio sources? Maybe a photo of the switch box connections or a link to the model of switch box that you're using. Is the isolation transformer on the power connections or along the inputs and how is it connected? The more details you can provide the better.

Powered speakers, w/TV and Mac as audio sources. Photo included
Iso trans between TV and switch; connected with rca cables. I cant think of more relevant details.

 

[Uncle Sammy]

Powered speakers, w/TV and Mac as audio sources. Photo includedView attachment 52311
Iso trans between TV and switch; connected with rca cables. I cant think of more relevant details.

 

[Eppie]

My preference is for switch boxes with a metal case and rotary knob like these ($40-$80), although the $40 Solupeak looks to be good enough. Channels should not cut out or switch left and right. Something odd going on there. Make sure your RCA cables are working ok. Connect one device directly to the speakers and test each cable.

Is the TV producing the hum? Sometimes the cablebox connected to the TV can be the source of the hum. Do you have all devices plugged into the same outlet? A ground lift plug (three prong to two prong adapter) on one device can sometimes remove the hum if it's a ground loop issue. Isolation transformers require a separate coil for each audio channel, so you need two individual transformers or a stereo device like this one, but whether it will work or not depends upon the source of the hum. Something as simple as a bad ground on an RCA cable can cause cables to pick up noise from flourescent lighting, for example, so you need to take a step by step approach to track down the source.

 

[BMXTRIX]

I would agree strongly that your use of blister pack RCA cables is a serious problem.

Overall, you have found a twenty cent solution to a twenty dollar problem and are wondering why you are having issues.

First, I would switch the RCA cables over to something of better build quality. You don't have to spend a ton, but I would get some decent cables since those cheap ones you have notoriously fail and cause audio issues... like a channel dropping out or severe noise.

Monoprice or Amazon Basics models will be fine...

https://www.amazon.com/Monoprice-1-5ft-Premium-22AWG-Cable/dp/B003L1717K/ref=sxin_13_ac_d_mf_br

https://www.amazon.com/AmazonBasics-2-Male-RCA-Audio-Cable/dp/B01D5H8PQ0/ref=sxin_13_ac_d_mf_br

Then get a decent RCA switch like the one listed. It does sound like the coax cable coming into the home may also be creating an issue, but as stated, one step at a time is the best course of action.

 

[Uncle Sammy]

My preference is for switch boxes with a metal case and rotary knob like these ($40-$80), although the $40 Solupeak looks to be good enough. Channels should not cut out or switch left and right. Something odd going on there. Make sure your RCA cables are working ok. Connect one device directly to the speakers and test each cable.

Is the TV producing the hum? Sometimes the cablebox connected to the TV can be the source of the hum. Do you have all devices plugged into the same outlet? A ground lift plug (three prong to two prong adapter) on one device can sometimes remove the hum if it's a ground loop issue. Isolation transformers require a separate coil for each audio channel, so you need two individual transformers or a stereo device like this one, but whether it will work or not depends upon the source of the hum. Something as simple as a bad ground on an RCA cable can cause cables to pick up noise from flourescent lighting, for example, so you need to take a step by step approach to track down the source.

I'll try the $40 Solupeak.

The dropped audio channel only occurs when both TV and Mac are linked thru switch to speakers. TV direct to speakers outputs both channels. I had previously substituted different cables. So, logically and by testing, swtich, not cables, is the cause of the dropped channel. A local techie agrees that this process of elimination proves the switch is bugged.

I just tested all devices powered from the same outlet but bug remains.

>A ground lift plug (three prong to two prong adapter) on one device can sometimes remove the hum if it's a ground loop issue.

Thats confusing and worrying. Wont that eliminate the safety of the newer 3-wire grounded outlets? I only use adaptors for other ,older devices & power cables

> Isolation transformers require a separate coil for each audio channel, so you need two individual transformers or a stereo device like this one, but whether it will work or not depends upon the source of the hum.

My isolation trans. looks like yours. I have tried a 15A and a 20A. Nothing indicates stereo. Mine is between TV and switch. I even tried adding the other between Mac and switch. Are you suggesting 1 or 2 between switch and speakers?