Loss in audio quality when using RCA input selector box

[Lance7489]

I own a Parasound P7 preamp & need more than the 2 multichannel inputs the unit offers. I also have a Involve Audio Surround master V3, but as everyone knows, those just have 1 analog input, which , I need more than that. I've been using analog RCA selector boxes to expand the number of inputs. There's a problem with that that I just discovered. There's a definite loss of audio quality when running the signal (CD player, DVD player, Blu-ray player, CD-4 disc demodulator etc) through any of these boxes, most noted in the higher frequencies. If I plug any of these units directly into my Parasound P7, they sound great. If I go through any of my RCA input selector boxes, there's a clear loss of sound quality.

Any suggestions??.............It seems that when the selector boxes are loaded up with components, it changes the input "load" going into the Parasound P7 inputs, thus affecting the sound quality..........could that be what's happening??............The boxes I'm using probably aren't the greatest quality (pd about $40 a piece for them).

Does anyone know of any higher quality selector boxes that won't have this problem???

 

[gene_stl]

What kind of selector box are you using?
Have you measured the high frequency loss or seen it on an oscilloscope? It should be easy to see if you put square waves through , as a loss of rise time.

 

[ar surround]

Lance, do your RCA selector boxes have a simple manual selector switch? Or do the have a remote control? If they have a remote, perhaps the circuitry in the box is somehow affecting what passes through it?

 

[Lance7489]

What kind of selector box are you using?
Have you measured the high frequency loss or seen it on an oscilloscope? It should be easy to see if you put square waves through , as a loss of rise time.

Something called Solupeak I bought on amazon. I have no scope, not a technician or anything. Can tell by my own ears. It's pretty obvious.

 

[Lance7489]

Lance, do your RCA selector boxes have a simple manual selector switch? Or do the have a remote control? If they have a remote, perhaps the circuitry in the box is somehow affecting what passes through it?

No remote, just a manual dial.

 

[Lance7489]

A thought just came to me. I'm wondering if it's the Parasound RCA inputs. Maybe the design somehow prohibits the use of selector boxes. Parasound seems to be a bit of a quirky company. They make good stuff but then they do strange things like putting tone controls on the front & center channels but none on the rear channels of the P7.

 

[LuvMyQuad]

A thought just came to me. I'm wondering if it's the Parasound RCA inputs. Maybe the design somehow prohibits the use of selector boxes. Parasound seems to be a bit of a quirky company. They make good stuff but then they do strange things like putting tone controls on the front & center channels but none on the rear channels of the P7.

I wouldn't stake any hopes on a proprietary switch selector prohibit circuit thingy. But ya never know with that sneaky John Curl guy.

I use a mechanical Philips video unit and I hear no difference. The Phillips is strictly a switcher. There are no other internal components. There is no difference in the circuit foils for the component video as compared to the audio channels. Some units are actually splitter/switches. By that I mean they can take a video signal input and feed it to multiple outputs. That involves splitter components in order to provide the proper impedance.. They may be in the signal path. There would also be a small gain loss. Make sure your device doesn't do that. Can you select more than one output simultaneously?

 

[Lance7489]

I wouldn't stake any hopes on a proprietary switch selector prohibit circuit thingy. But ya never know with that sneaky John Curl guy.

I use a mechanical Philips video unit and I hear no difference. The Phillips is strictly a switcher. There are no other internal components. There is no difference in the circuit foils for the component video as compared to the audio channels. Some units are actually splitter/switches. By that I mean they can take a video signal input and feed it to multiple outputs. That involves splitter components in order to provide the proper impedance.. They may be in the signal path. There would also be a small gain loss. Make sure your device doesn't do that. Can you select more than one output simultaneously?

This is the one I'm using. I don't know what this qualifies as (a switcher or a splitter/switcher). The biggest change I notice when I go through this is a loss with the higher frequencies.

 

[Lance7489]

I wouldn't stake any hopes on a proprietary switch selector prohibit circuit thingy. But ya never know with that sneaky John Curl guy.

I use a mechanical Philips video unit and I hear no difference. The Phillips is strictly a switcher. There are no other internal components. There is no difference in the circuit foils for the component video as compared to the audio channels. Some units are actually splitter/switches. By that I mean they can take a video signal input and feed it to multiple outputs. That involves splitter components in order to provide the proper impedance.. They may be in the signal path. There would also be a small gain loss. Make sure your device doesn't do that. Can you select more than one output simultaneously?

What I meant with parasound is that maybe the required impedance of the inputs is different than other manufacturers & the use of switchers somehow throws off that impedance.

 

[LuvMyQuad]

That switcher is made for audio. No video involved. Do you use 2 of them for quad?

 

[LuvMyQuad]

What I meant with parasound is that maybe the required impedance of the inputs is different than other manufacturers & the use of switchers somehow throws off that impedance.

There should be no impedance change from a simple switch. Odd,

The additional caballing involved would.

 

[Lance7489]

That switcher is made for audio. No video involved. Do you use 2 of them for quad?

Yes.

 

[Lance7489]

There should be no impedance change from a simple switch. Odd,

The additional caballing involved would.

When the source is plugged directly into the preamp, sounds fine. When it's plugged into the switch box, (with the other components plugged in) then from the box into the preamp, a noticeable loss of high end.

 

[gene_stl]

and 3 for 5.1?
is there only one of the two outputs in use?
I think if you open this style all that is inside is a wafer rotary switch. No circuitry. You probably should unscrew the panels and take a look (and a snapshot)

If you only plug one component into the switch box does it still cause the high frequency losses? Does it still happen when the test is done blindly?

 

[4-earredwonder]

When the source is plugged directly into the preamp, sounds fine. When it's plugged into the switch box, (with the other components plugged in) then from the box into the preamp, a noticeable loss of high end.

Are ALL your RCA cables of similar quality? IMO, cables do make a difference despite what the naysayers say!

 

[gene_stl]

try two of these
https://www.amazon.com/CIMPLE-CO-Selector-Composite-Switcher/dp/B07C15LT9S?th=1I have a version of this and it has no components on the board except switches. The only difference in the video channel is the color of the RCA

 

[Lance7489]

and 3 for 5.1?
is there only one of the two outputs in use?
I think if you open this style all that is inside is a wafer rotary switch. No circuitry. You probably should unscrew the panels and take a look (and a snapshot)

If you only plug one component into the switch box does it still cause the high frequency losses? Does it still happen when the test is done blindly?

Both outputs are in use. A goes to the Surround master & B goes to a stereo input on the parasound P7. I use the above pictured switch so I can send all my 2 channel components to either the surround master for 5.1 or to the P7 if I feel like listening to straight stereo.

For either 4 or 5.1 channel sources (blu ray, multichannel SACD or CD-4), I use 2 of the below pictured:

 

[Lance7489]

Are ALL your RCA cables of similar quality? IMO, cables do make a difference despite what the naysayers say!

Sorry to say they aren't. I have some high-quality cables, but I also have some "cheapies" I purchased from amazon. I always thought of cables in the mindset that they either work or they don't. If I do find my problem is "cable related", it'll be a revelation, I never would have thought cheapie cables would basically work but have that much of an adverse effect on sound quality.

 

[Lance7489]

and 3 for 5.1?
is there only one of the two outputs in use?
I think if you open this style all that is inside is a wafer rotary switch. No circuitry. You probably should unscrew the panels and take a look (and a snapshot)

If you only plug one component into the switch box does it still cause the high frequency losses? Does it still happen when the test is done blindly?

Yeah, I'll have to play around with the box "empty" (with the exception of 1 source) vs fully loaded. If I open the box up, what am I looking for? Not sure what you mean by blindly

 

[gene_stl]

Someone else switches the box in or out without you knowing it is a blind or blinded test.

What I expect you will see if you open it is two "wafer" style switches and wiring in between.

you also should check it (preferably blindly) between the two outputs. and with a single device trying all the different inputs.