Looking to build a listening room in my basement with different combinations of pre-amps, amplifiers and speakers. It be strictly a 2 channel system with variations of tube and solid state equipment as well as a variety of speakers.
Does anyone have a suggestion or recommendation on a switching controller that could handle input and output selctions, sort of like what they have in profesional listening rooms? Something where I can select different combinations? For example, select pre-amp A, run through amplifer C, and then output to speaker set B.
I'm sure I can call a few local places in ATL, but thought I'd check here first. Google isn't coming up with squat.
Thanks!
Does anyone have a suggestion or recommendation on a switching controller that could handle input and output selctions, sort of like what they have in profesional listening rooms? Something where I can select different combinations? For example, select pre-amp A, run through amplifer C, and then output to speaker set B.
I'm sure I can call a few local places in ATL, but thought I'd check here first. Google isn't coming up with squat.
Thanks!
For the inputs, what you need is usualy called an audio matrix. So in the rows, you can put sources (PC; Phono; radio; CD; TV, etc) and in the cols, the destiny of the input selected (Amp A; Amp B, etc.) and so on. You can build it simply with double pole switches for both stereo channels. This enables the use of a single source for more than one amplifier, for example listen the same CD at kitchen and garage with different volumes if desired, using diffetent amplifiers. Two or more inputs to a single amp will be a bit confusing 😲 
Other alternative is a mixer but you will need one stereo mix per amplifier to use.
The same for the speakers, but here good relays are suggested taking into account not to cross connect two or more speakers into a single amp if it doesn't support too heavy load.
Other alternative is a mixer but you will need one stereo mix per amplifier to use.
The same for the speakers, but here good relays are suggested taking into account not to cross connect two or more speakers into a single amp if it doesn't support too heavy load.
So far, I have not found anything that suits my needs. I've searched under Matrix, Amplifier Switch, Listening Room Controller, and other such keywords, but all that ever comes up are systems to branch an amplifier to speakers in different rooms.
What I need is an active controller with relays that will switch between 6-10 amplifiers, 6-10 preamps, and 6-10 speaker pairs. Kind of what you would find when you go to a high-end audio store and sit in their listening room. For example, "I want to hear the McIntosh MAC7200 Receiver coupled with the MartinLogan ESL 11A speakers." and then they go to the control panel (or tablet) and select which amp and speaker combo to run. It has to be capable of disconnecting the current amplifier before connecting the next one, for obvious reasons.
I know this is a pretty complicated system, but every listening room I've been to (including the one at Best Buy) has this type of system to control the wide range of components they display. I just want something like this so that I can switch between my different components without having to unplug/plug cables or result to using the garbage I've found online so far (Amazon and Crutchfield come to mind).
Building a system like this wouldn't be terribly difficult, but the prices of components has gotten so expensive that it's probably cheaper to find something already built and just plugs in.
Anyway, thanks for the suggestion. It didn't seem to fit my needs but is much appreciated.
There is a device that does exactly what you want; but it has fewer in/outs, search the web for Pioneer U-24 Program Selector. There are surely other brands, too.
Time ago I also wanted to do the same as you (and still I am, but no free time enough ); I even made the blocks diagram and purchased some relays...
Two final comments regarding your project:
1) It is not safe to commute the output of tube amps unless you take extra precautions (inductive loads, amp's outputs cannot be left open, etc.)
2) If you just want to switch devices the project can be simple; but if you want to do listening tests to compare them additional complexity is needed like carefully level matching, phase verification, etc.
I hope this helps.
Time ago I also wanted to do the same as you (and still I am, but no free time enough
); I even made the blocks diagram and purchased some relays...Two final comments regarding your project:
1) It is not safe to commute the output of tube amps unless you take extra precautions (inductive loads, amp's outputs cannot be left open, etc.)
2) If you just want to switch devices the project can be simple; but if you want to do listening tests to compare them additional complexity is needed like carefully level matching, phase verification, etc.
I hope this helps.
Yamaha YSU-3 and YSL-3
Audio Authority in Lexington, Kentucky manufacture comparators for showroom.
https://www.audioauthority.com/product_details/903i
That is actually a really cool looking component. I may have to see about picking one up just to keep in my equipment portfolio.There is a device that does exactly what you want; but it has fewer in/outs, search the web for Pioneer U-24 Program Selector. There are surely other brands, too.
Time ago I also wanted to do the same as you (and still I am, but no free time enough
Two final comments regarding your project:
1) It is not safe to commute the output of tube amps unless you take extra precautions (inductive loads, amp's outputs cannot be left open, etc.)
2) If you just want to switch devices the project can be simple; but if you want to do listening tests to compare them additional complexity is needed like carefully level matching, phase verification, etc.
I hope this helps.
That aside...
The more I'm looking at this, the more I think I'm going to build my own. This way, I can make it do exactly what I'd like. I've already started laying out the circuit board and spent the better part of the day researching and sourcing parts.
As you indicated, the biggest problem I have to address is leaving an amp on with no speaker load attached to it. This shouldn't be too bad to resolve by incorporating inductors in each amp input circuit so that when they aren't "live", they switch from the output bus to their own inductor so that there is a load applied. For what it's worth, I could probably just use cheap voice coils with a carbon filler as the load. I was originally looking at solid state versions using MOSFETs to handle the switching, but for all practical purposes it's just easier to use relays. Especially if I'm going to be tying the amp output to a load when idle, not just disconnecting that channel.
I may still use a MOSFET switch on the signal bus in order to momentarily kill the output while the relays disconnect and reconnect, which should help eliminate (or at least reduce) strain on the contacts. Looking at the specs, I can get the switch to occur in less than 5 mSec, most of which would be to account for allowing the relay to settle before reapplying the amp output. This would eliminate the need to turn down the amp before switching, although that's probably a still good idea in the end.
The only other issue to deal with would be differences in amp output impedence and speaker impedence. That's going to be a little bit trickier to deal with. I could probably just use two different power rails (one 4 ohm and one 8 ohm), tie the amps to both rails, and then select which rail to used based on the speaker specs being selected. 4 ohm speakers to 4 ohm rails and 8 ohm speakers on 8 ohm rails. I suppose I'd still tie the inputs to its own 8 ohm inductor when that particular amp is idle.
Of course, ALL of this is going to require a processor to handle the input, the switching, and the device configuration for inputs and outputs. This isn't a huge deal for me since that's the bulk of what I do for a living anyway.
At this point, without circuit board costs, it'll probably run in the area of 1000 in hardware (case, binding posts, relays, inductors, wiring, etc.). It's an interesting project and I think it will give me a project to play with over the Christmas holiday.
I can already see that there are lots of ways to go with this. If anyone has any suggestions, comments, opinions, circuit designs, or anything else they'd like to offer up, I'm certainly game and would greatly appreciate it.
The Yamaha does not load the unused output.
To be safe, short the power amp input to ground and connect a resistor to output as a dummy load. Since the power amp input is shorted, there should be no output signal so a low wattage resistor will do.
Hi Bill:
I think building it by yourself is the way to get it right as you need it.
You don't need to use inductors as loads, resistors are fine (8 ohms or indicated nominal impedance). I mentioned inductive loads because it is not safe to commute a speaker while playing music (specially ones with complex crossovers), they can generate high voltage spikes.
Solid state amps usually have no problem if you leave the output without connection, but tube amps will need to be loaded with a resistor when not used. If you do the commutation while not playing music, you can first connect the resistor at the output in parallel and then disconnect the speaker, no harm for the amp. I have several pairs of mini-monitors and I connect the next one that I want to listen to before disconnecting the other when I am using my tube amp (the switcher is an Adcom, manual, plain switches of good quality).
For the comparison of power amps I suggest you place some level control for each switcher output so you can adjust level, a pink noise generator included in your switch box will be handy.
I think building it by yourself is the way to get it right as you need it.
You don't need to use inductors as loads, resistors are fine (8 ohms or indicated nominal impedance). I mentioned inductive loads because it is not safe to commute a speaker while playing music (specially ones with complex crossovers), they can generate high voltage spikes.
Solid state amps usually have no problem if you leave the output without connection, but tube amps will need to be loaded with a resistor when not used. If you do the commutation while not playing music, you can first connect the resistor at the output in parallel and then disconnect the speaker, no harm for the amp. I have several pairs of mini-monitors and I connect the next one that I want to listen to before disconnecting the other when I am using my tube amp (the switcher is an Adcom, manual, plain switches of good quality).
For the comparison of power amps I suggest you place some level control for each switcher output so you can adjust level, a pink noise generator included in your switch box will be handy.
I agree. Since this is a specifically custom situation given the hardware, I think just building it would be a great approach.
This is good to know. The reason I had considered inductors is because I figured that they would handle the load better than a resistor would, at least with some level of signal applied. This is also the reason I'm looking to do a solid state switch using MOSFETs that will "fade" the signal going out and coming in. This would allow for a the relays to transition without "popping" and can soft-start the signal back onto the bus.
Obviously, a quality resistor would be less expensive than inductors, But I'll leave the option open on the circuit board just in case it doesn't work like I expect. If the resistors become a problem with the load, then I can just add the inductors as needed. It doesn't cost anyting to run the extra traces and pads.
Great suggestions. I'll look at what that would entail. I wanting to keep this all digital as much as possible, but I could see where an L-Pad for each output or a pot for the inputs could be useful and not introduce any noise or coloration of the signal. Pots seem like a better idea as it's always seems a bit tough when dealing with the output signal control.
As I'm looking at this in more detail, it becomes clear to me that when switching amplifiers, I'll also need to switch the inputs on and off as well. This way I can run a signal in from a single point (or multiple points, if desired), and then switch the outputs on and then switch the inputs on. This would help ensure no signal to the amplifier and ultimately no output to the speakers when switching. This makes using a resistive load much more feasible.
Adding a signal generator or pink/white noise would be easy, since I'd be controlling the source anyway.
Now to start blocking out the layout and get to work on the schematic!
Thanks!! 😁