Speaker Selector Switchbox changes audio quality?

[canidoit]

Hi All,

For years I have been using this speaker selector below, as advised by the electronic store as being the best as it has impedance circuitry in there to accommodate different ohms speakers so that it does not change the audio quality.

I have been connecting 4 and 8 ohms speakers to it but noticed that sometimes, the speakers would fluctuate between being slightly darker and slightly brighter. For decades I thought it was my tinnitus or head movement, but now after reading some information online that it is possibly the speaker selector/switchbox?

From what I read, an amp's circuit remains at the state of the previous speakers and does not adjust to the new requirements of the new speakers when selected using the speaker switch, hence why it may cause a change in the audio quality? Is this correct?

If I were to use the speaker selector, would it best to keep all speakers connected to be of the-same ohms? Will this still cause sound quality variances?

There are some expensive basic 2 way speaker selectors that use heavy duty switches, are they any better or will they still have the-same issue when using different ohm speakers in the setup?

Thank you.

 

[radardoug]

Well, we dont know whats in the box, but I am betting not much. If its just switches on the speaker side, it wont be affecting anything.
And of course you give us very little actual information to advise you on, no model number or brand.

 

[Paul W]

In the picture the device has what appears to be the brand/model printed on it, "Solupeak P3".
Googling turns up this, which appears to indeed be a passive switch box.

https://www.amazon.com/SOLUPEAK-P3-Amplifier-Speakers-Selector/dp/B0BGHMGY7J?th=1

 

[JohnRoberts]

I found a P3 listing on amazon that said

NOTE:
No protection or impedance matching circuits internal, so could not affect sound quality,

Since they said that it must be true

JR

 

[scott2000]

Guess I'm weird but there are not many pieces of audio gear that aren't opened for a peek not too long after they are in my possession....

 

[Brian Roth]

Now I'm confused. The first pic the OP posted was for a "SS450", but then the discussion (and second pic) veered to the "P3".

Bri

 

[Disco Volante]

To try to answer OP's questions:

An amp does not need time or effort to adjust to the speakers.
Any well-designed amp will be able to handle the impedance of reasonably well-designed speakers, be they called 4 or 8 or gazonka ohms. A well-designed amp should be able to handle any speaker, actually.
Do an impedance plot of your speakers, you'll find that they are anywhere between, say, 3 and 50 ohms over the audible frequency range. It is easily done with a 2-channel soundcard and REW.

As for the speaker switch, you are switching high currents, so a big switch will be "better" than a small one. Whether anyone will be able to hear it is another question. I know that the audiophools shun such switches (it would sort of void any point in buying $1000+ cables, if there was any in the first place).
Avoid any switches with correction circuits, for the above reasons.

Cheers, V!

 

[canidoit]

The Selector I own(first pic) I think has some resistors/capacitors in there to handle different impedence?

The example(second pic) uses toggle switch and straight wiring.

I read somewhere that flipping selector switch between two amps could be an issue, could an amp blow up?
As for, two speakers and one amp, would there be any problems, like feedback or possibly a pop from the switching?

I feel like building my own, but wondering if its cheaper to buy one online, their like $80-$90 AUD each.

 

[Voyager10]

Regarding switching one speaker between two amps - it's important that both wires (+ and -) are switched. It can't assume that '-' is ground (for any value of 'ground') and so connect these inputs together.

Secondly the switch needs to be 'break before make'. Some (usually rotary) switches are 'make before break' so would momentarily short the two amps together.

Last thing - don't do this with a tube amp. They are generally not designed to be run with no output load.

 

[Newmarket]

From what I read, an amp's circuit remains at the state of the previous speakers and does not adjust to the new requirements of the new speakers when selected using the speaker switch, hence why it may cause a change in the audio quality? Is this correct?

No. That just isn't how an amplifier / speaker interface works. Caveat: with some valve output amplifiers you may need to select the correct transformer tap.
But a switching box should just... switch. Best practice would be to mute signal when switching.
Extra thought may be needed if driving the speakers in bridged mode.

 

[JohnRoberts]

Regarding switching one speaker between two amps - it's important that both wires (+ and -) are switched. It can't assume that '-' is ground (for any value of 'ground') and so connect these inputs together.

Secondly the switch needs to be 'break before make'. Some (usually rotary) switches are 'make before break' so would momentarily short the two amps together.

Last thing - don't do this with a tube amp. They are generally not designed to be run with no output load.

yup, you can blow up tube amps with simple speaker switches. There was even a warning about that in the Amazon product write up.

JR

 

[ccaudle]

The Selector I own(first pic) I think has some resistors/capacitors in there to handle different impedence?

Seems unlikely. Open the case and find out.

The pictures I could find of your SS450 switcher and the Radio Shack North American equivalent show typical low quality spring wire clips. Those don't provide great contact, perhaps one of your speaker wires just has some oxide build up.

From what I read, an amp's circuit remains at the state of the previous speakers and does not adjust to the new requirements of the new speakers when selected using the speaker switch, hence why it may cause a change in the audio quality? Is this correct?

Much closer to complete nonsense than to accurate information.

 

[Newmarket]

For clarity - there is no good reason for a switching box to incorporate any impedance modifying components or network. Any such networks eg Zobel/Snubber should properly be incorporated into the amplifier and/or speaker.

 

[canidoit]

Does anyone have any recommendations for an affordable switchbox that does not compromise sound quality or am I better off just DIY my own?

What sort of 3 way toggle switch would be most suitable if that was the case, or is 2 way the better option? I have seen those rotary switches being used, but are toggle switches better?

Thank you all for their replies!

 

[Brian Roth]

IMHO, switching speaker-level signals from a single power amplifier into multiple sets of speakers is just asking for trouble. Better (and much more expensive!) solution is dedicate one power amp per speaker set and switch the inputs into the amplifiers.

Bri

 

[kidb]

I’ve used an Adcom gfs-6 for decades, no issues whatsoever, just my two cents!

 

[Mr. Moscode]

To the arrogant know-it-alls that use the term "audiophools" - stop it. If you have not researched this issue then you aren't in any way qualified to pass judgement. Reminder: scientific method requires peer review. Otherwise it's very poor signal to noise ratio. At the end there's a screenshot showing what I'm talking about.

I have built switch and relay boxes for this purpose have never heard one that doesn't f-k up the sound in some way. Less is more. You have to have really good signals, amps and speakers to make it worthwhile, though. Even the wire can lose audio quality. I'd get rid of them. They're ok for the consumer grade convenience but you'll be much better off directly wiring the spkrs to the amps. You want to be professional, don't hinder yourself with inferior gear. It was clear to me that A-B boxes aren't good unless it's really well designed. It wasn't worth the effort to continue to use them.

Several things:

1. From the looks of the box these are double pole, double throw power switches. It's OK but switches that have a center off will isolate both speakers and amplifiers such that they can't be connected together, i.e. amp to amp or spkr to spkr.

2. Yes, switch contacts can degrade audio quality. It may be subtle but they will. If you are switching amps and speakers while playing there may be arcing on the internal switch contacts which will definitely degrade the connection. Speaker relays are subject to the same problems. Any thing between the amp output and the speaker can and probably will degrade the signal. Look at the screen shot.

3. Over time those switch contacts will oxidize unless they are fully gold plated and sealed, but they can still arc. Oxidation degrades the contacts and forms diode like connections that partially rectify the signal. If you flip the switch and each time the sound quality changes at all either oxidation or arcing could have occurred, even with self - wiping contacts.

4. My suggestion is to replace the toggle switches with DPDT center off gold plated types. Expensive, yes but much more reliable if you want to keep this box. You may have to find rotary switches. Also rate them for at least 20 amps. Better yet, wire up your best amp to the best speakers with your best wire and forget the box.

Here's a screenshot of audio trying to pass thru degraded contacts in speaker fuse holders. Note that in the lower trace there is diode rectification that drops in and out. Small signals will be affected most. I took this shot during routine amp testing.

Diode rectification is a one-way street.

 

[JohnRoberts]

To the arrogant know-it-alls that use the term "audiophools" - stop it. If you have not researched this issue then you aren't in any way qualified to pass judgement. Reminder: scientific method requires peer review. Otherwise it's very poor signal to noise ratio. At the end there's a screenshot showing what I'm talking about.

I wasted time re-reading this thread to find the cited insult (I didn't find it).

Over the decades I have wrestled with many audiophools but don't recall addressing individuals with that specific pejorative. I have used it in general when the shoe fits on sundry topics.
===
Regarding switch contacts degrading audio, yes faulty jacks and faulty switch contacts can be audible. Replace any faulty components.

In the course of doing my old day job we used plenty of A/B tests but I never used listening tests for primary design, mainly to confirm that I measured and optimized the correct design factors.

JR

 

[DarkSky]

IMHO, switching speaker-level signals from a single power amplifier into multiple sets of speakers is just asking for trouble. Better (and much more expensive!) solution is dedicate one power amp per speaker set and switch the inputs into the amplifiers.

Bri

This approach has several incidental benefits - one being that it will work with active (powered) speakers or a mix of active and passive systems, and another being that in the event that the speakers have differing efficiency (which is likely), it's far more straightforward to pad the 'louder' feeds to achieve level matching. While that's not *impossible* working on the amp outputs, it's considerably more expensive and also far more likely to introduce audible/undesirable artefacts (and to impact amp performance, damping etc.).

FWIW, I built a system that's been in use here for a number of years, that is using signal relays to divert the console 2-bus outputs to one of four monitoring systems, three of which are passive (each with its own dedicated power amp) and the fourth active. They're then matched/calibrated using level controls on each of the dedicated power amps. The quality of the relays matters, but not nearly as much as it would if they were switching the high current loads at the amp outputs.

 

[kags]

This approach has several incidental benefits - one being that it will work with active (powered) speakers or a mix of active and passive systems, and another being that in the event that the speakers have differing efficiency (which is likely), it's far more straightforward to pad the 'louder' feeds to achieve level matching. While that's not *impossible* working on the amp outputs, it's considerably more expensive and also far more likely to introduce audible/undesirable artefacts (and to impact amp performance, damping etc.).

FWIW, I built a system that's been in use here for a number of years, that is using signal relays to divert the console 2-bus outputs to one of four monitoring systems, three of which are passive (each with its own dedicated power amp) and the fourth active. They're then matched/calibrated using level controls on each of the dedicated power amps. The quality of the relays matters, but not nearly as much as it would if they were switching the high current loads at the amp outputs.

I have used patch panels with twin banana plugs (or XLRs) for manually patching from one amp between two sets of passive speakers. This encourages the user to stop the music, change the patch and then restart the music. That avoids switching powered signals. After the user got tired of that they would upgrade to a proper monitor controller and separate power amps. I also discourage users from playing more than one set of monitors simultaneously, but that’s another issue.