Switching between Amps, preamps, receivers, etc.

KEW

KEW

Audioholic Overlord
Please keep to the topic - methods of connecting & switching between components!

I would like to compare a couple of thirty year old integrated amps with modern gear, tubes against SS, separates against receiver, etc.
There are lots of conflicting opinions out there. I would like to do some comparisons, if practical, and find out for myself.

I believe the interruption required to reconnect components would undermine be problematic. I do not expect to hear major differences and believe an instantaneous method to switch back and forth is needed to really be able to home in on and confirm perceived differences and ultimately decide what I prefer (if differences do exist).

Is there a magic box which can do this at a reasonable cost? Or are there some clever ways to use a receiver or preamp as a switcher?

Thanks for the help!
 
Swerd

Swerd

Audioholic Warlord
Please keep to the topic - methods of connecting & switching between components!

I would like to compare a couple of thirty year old integrated amps with modern gear, tubes against SS, separates against receiver, etc.
There are lots of conflicting opinions out there. I would like to do some comparisons, if practical, and find out for myself.

I believe the interruption required to reconnect components would undermine be problematic. I do not expect to hear major differences and believe an instantaneous method to switch back and forth is needed to really be able to home in on and confirm perceived differences and ultimately decide what I prefer (if differences do exist).

Is there a magic box which can do this at a reasonable cost? Or are there some clever ways to use a receiver or preamp as a switcher?

Thanks for the help!
You want to use the same source and speakers but switch between various receivers or preamp/amps?

I know of no quick or clever way of doing this. They only way I can see doing this is the obvious way. Use a DVD/CD player with internal DAC, connect it via standard RCA analog cables to the receiver or preamp, and connect speaker wire using banana plugs for speed. Stick with the same music passage(s) and go back and forth repeatedly until you're certain of your impression.

Remember, if you have great difficulty coming up with a clear impression of audible differences between two devices, the simplest explanation is that there is little or no difference.
 
mtrycrafts

mtrycrafts

Seriously, I have no life.
Please keep to the topic - methods of connecting & switching between components!

I would like to compare a couple of thirty year old integrated amps with modern gear, tubes against SS, separates against receiver, etc.
There are lots of conflicting opinions out there. I would like to do some comparisons, if practical, and find out for myself.

I believe the interruption required to reconnect components would undermine be problematic. I do not expect to hear major differences and believe an instantaneous method to switch back and forth is needed to really be able to home in on and confirm perceived differences and ultimately decide what I prefer (if differences do exist).
You might get away with a Y connector for the RCA inputs and only need a double pole-double throw switch for each speaker ch.

Is there a magic box which can do this at a reasonable cost? Or are there some clever ways to use a receiver or preamp as a switcher?

Thanks for the help!
There may be one ABX box on the market but it isn't that cheap, if I recall.

For what you are after, a switching box is needed for each input and output types of configuration, speaker cable, RCA or digital, preferably switching with one command.
The longer you take to switch to more memory is lost. Same goes for the music segments you will compare.
Not an easy task for meaningful results.
 
JerryLove

JerryLove

Audioholic Samurai
Comparing two at a time? Might I suggest a Y-cable?

Obviously, you could also use any pre-amp with more than one output.
 
highfigh

highfigh

Seriously, I have no life.
Please keep to the topic - methods of connecting & switching between components!

I would like to compare a couple of thirty year old integrated amps with modern gear, tubes against SS, separates against receiver, etc.
There are lots of conflicting opinions out there. I would like to do some comparisons, if practical, and find out for myself.

I believe the interruption required to reconnect components would undermine be problematic. I do not expect to hear major differences and believe an instantaneous method to switch back and forth is needed to really be able to home in on and confirm perceived differences and ultimately decide what I prefer (if differences do exist).

Is there a magic box which can do this at a reasonable cost? Or are there some clever ways to use a receiver or preamp as a switcher?

Thanks for the help!
If you connect the sources to one preamp, you can use the record output to send a buffered signal to all of the rest of the preamps & receivers. Then, you can connect the various preamps to the power amps by unplugging the cables to the power amp and plugging it into each preamp or receiver. Anything the signal goes through will change it slightly, so you'll want to have the shortest and simplest path possible.

One thing you want to remember is that when you connect and disconnect speakers to a tube power amp(s), it should be off. Tube amps don't like to run with no load. Also, make sure the speakers are connected when the power is turned on and off. No load can cause arcing in an output transformer and when this happens, it needs to be replaced.
 
KEW

KEW

Audioholic Overlord
You want to use the same source and speakers but switch between various receivers or preamp/amps?
Yep, you got it!

Remember, if you have great difficulty coming up with a clear impression of audible differences between two devices, the simplest explanation is that there is little or no difference.
Making that determination is as much of what I am after as anything.
 
KEW

KEW

Audioholic Overlord
Okay, I was hoping I could go to Radio Shack and get a magic box or two, but I guess that is wishful thinking.

How about this. I have two identical Marantz receivers which I can put in "pure direct" mode to minimize their influence.

CD/DAC output to CD input of R1 (receiver 1)
Tape output of R1 to Tape input of R2
At this point I can use the remote (common to both receivers) to select Tape or CD and the output signal will switch between the two units.

Things I'm not sure of:
1) Can I feed "pre-amp output" into either another preamp or into a power amp (isn't the line essentially still at line level)? If so, that solves the issue of switching the signal going into the components.
2) Are there problems with having two amps hooked into the same pair of speakers even though only one of the amps is receiving a signal at a time?

I've got some expendable boom box test speakers for proving things out, but I would not want to screw up the amps!

I know this is not theoretically perfect, but it seems good enough for practical purposes. If I notice a difference, I can swap the connections between the receivers and the components being tested to see if my preference is still the same.

Thanks!
 
highfigh

highfigh

Seriously, I have no life.
Okay, I was hoping I could go to Radio Shack and get a magic box or two, but I guess that is wishful thinking.

How about this. I have two identical Marantz receivers which I can put in "pure direct" mode to minimize their influence.

CD/DAC output to CD input of R1 (receiver 1)
Tape output of R1 to Tape input of R2
At this point I can use the remote (common to both receivers) to select Tape or CD and the output signal will switch between the two units.

Things I'm not sure of:
1) Can I feed "pre-amp output" into either another preamp or into a power amp (isn't the line essentially still at line level)? If so, that solves the issue of switching the signal going into the components.
2) Are there problems with having two amps hooked into the same pair of speakers even though only one of the amps is receiving a signal at a time?

I've got some expendable boom box test speakers for proving things out, but I would not want to screw up the amps!

I know this is not theoretically perfect, but it seems good enough for practical purposes. If I notice a difference, I can swap the connections between the receivers and the components being tested to see if my preference is still the same.

Thanks!
Radio Shack doesn't sell "magic boxes" and when comparing equipment, ANY connection between the source and preamp, preamp and power amp or power amp and speakers has the potential to obscure any quality differences. Think about some of the topics of discussion here and in other forums- people think a power cable that replaces one that is perfectly capable of delivering the voltage and current needed for a receiver, preamp or power amp and isn't even in the signal path, speaker cabling that replaces other cable that's again, perfectly capable of delivering the signal or interconnects that are carrying low voltage audio signals over short distance, adding connections in the signal path isn't going to be totally transparent.

1.) If you feed signal to another preamp, use the tape loop- it's a fixed level and preamp output line level is for feeding a power amp. A system has several areas where the signal experiences gain and the preamp is part of the gain structure of the system. Output and input impedances need to be correct, too, and tape input is often in the 100K Ohm range while power amp input is frequently in the 1 MegOhm range.

2.) You don't want to connect two amplifiers to the same pair pf speakers.

If you want to hear the difference between two amps, using boombox speakers is not the way to do it.
 
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KEW

KEW

Audioholic Overlord
Radio Shack doesn't sell "magic boxes" and when comparing equipment, ANY connection between the source and preamp, preamp and power amp or power amp and speakers has the potential to obscure any quality differences. Think about some of the topics of discussion here and in other forums- people think a power cable that replaces one that is perfectly capable of delivering the voltage and current needed for a receiver, preamp or power amp and isn't even in the signal path, speaker cabling that replaces other cable that's again, perfectly capable of delivering the signal or interconnects that are carrying low voltage audio signals over short distance, adding connections in the signal path isn't going to be totally transparent.
Yeah, it definitely would not be perfect, but my thinking was this would equally compromise both the A and the B components.

1.) If you feed signal to another preamp, use the tape loop- it's a fixed level and preamp output line level is for feeding a power amp. A system has several areas where the signal experiences gain and the preamp is part of the gain structure of the system. Output and input impedances need to be correct, too, and tape input is often in the 100K Ohm range while power amp input is frequently in the 1 MegOhm range.
2.) You don't want to connect two amplifiers to the same pair of speakers.

If you want to hear the difference between two amps, using boombox speakers is not the way to do it.
Just to clarify, when I said "I've got some expendable boom box test speakers for proving things out..." I meant proving out the connections. Once I established that the boom box speakers survived, then I would switch to a speaker which would be able to capture subtleties.
 
ski2xblack

ski2xblack

Audioholic Field Marshall
Unless you can eliminate all other variables (and you can see from the other responses that that is difficult), not to mention devising a statistically accurate method of measuring human hearing (which currently does not exist), you would be better off just trying the amps and evaluating your subjective enjoyment of each. That's what I did...inaccurate, high output impedance, measure-like-crap SET's won hands down. The difference was so distinct that the time spent swapping amps was not an issue.

What amps are you comparing?

I saw some home brew switchers at RMAF yesterday that would suit your purposes, but you would have to build something like that. If you did, at least all of the connections would be matched for comparison purposes.
 
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walter duque

walter duque

Audioholic Samurai
I use a rca switcher from radio shack, which has 1 rca input(stereo) and 4 switchable rca(stereo) outputs. You could run a pre-pro to input and switch between 4 poweramps. I don't know it this would help you. You might need a few of these. Then you still need a speaker selecter. 4 in-1out.
 
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lsiberian

lsiberian

Audioholic Overlord
Please keep to the topic - methods of connecting & switching between components!

I would like to compare a couple of thirty year old integrated amps with modern gear, tubes against SS, separates against receiver, etc.
There are lots of conflicting opinions out there. I would like to do some comparisons, if practical, and find out for myself.

I believe the interruption required to reconnect components would undermine be problematic. I do not expect to hear major differences and believe an instantaneous method to switch back and forth is needed to really be able to home in on and confirm perceived differences and ultimately decide what I prefer (if differences do exist).

Is there a magic box which can do this at a reasonable cost? Or are there some clever ways to use a receiver or preamp as a switcher?

Thanks for the help!
I suggest you treat this as a series of scientific experiments.

You'll need only an SPL meter and frequency sweep.
 
mtrycrafts

mtrycrafts

Seriously, I have no life.
....not to mention devising a statistically accurate method of measuring human hearing (which currently does not exist), .....
Not sure what you are driving at with this???
 
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