Due to space and money shortage, I've been using my hi-fi amp to provide power output for my keyboards. I can connect 2 boards to the TAPE IN jacks on my amp through a pair of Y cable adapters plus a pair of phono-to-RCA plugs. Everything seems OK except for one thing: to get full volume output from my Yamaha CSX both keyboards need to be on -- if only the CSX is on, I only get half the sound volume from it. Whereas my Alesis QS doesn't care if it is going solo or in tandem with the Yamaha, it still provides full volume. My question is: Will this be bad for my boards in the long run? And if someone could recommend an affordable solution, it would surely be appreciated.

I would be more worried about it affecting the power amp than the keyboards. There must be some glitch in your hookup where one side of one keyboard is running through the other. Just guessing.
It would be easy to get a little line-level mixer from somewhere like Radio Shack. Quite inexpensive.
DonM

I was thinking of a similar cause along that line -- the glitch may be in the Y cables that somehow reroute the signal flow. The Y connection takes place before the amp input jacks, and that makes them possible culprits. But the two boards are on a parallel- not serial- hookup, with signals being sent out from their output jacks! At any rate, I appreciate your input, and may have to follow your advice and add a mixer into the line. Thanks, DonM.

Another warning!
You are not using your hi-fi speakers are you?
In case you do, be prepared for blowing them up!
Consumer speakers cannot handle instruments!
The peaks are way to high!

I would guess this is going to damage your boards in the long run. I am no electrical engineer, but as far as I know, the inputs of electrical gear have high impedance while outputs have low impedance. When you connect the two keyboard through a Y cable you are in effect connecting the outputs of the keyboards as well; that is you are connecting two low impedance terminals. So a signal that appears at the output of one keyboard can easily intrude the other due to the low impedance and can damage it in the long run.

Again, I am no expert, but you will be at the safe side using an inexpensive mixer. Have you tried Behringer mixers? They are pretty good for that price.

Shiral

Guilty as charged. I use a pair of JBL J2050 for everything, and I surely don't want to ruin them as I probably won't be able to replace them anytime soon. My temporary solution is to run the amp around 10 - 12 o'clock at maximum. But I know your warning all too well having blown a pair of speakers before (good thing, they were inexpensive ones.) Still, that was when I still had my day job so they were promptly replaced. You can rest assured I won't be making the same mistake now.

That sends a shiver up my spine, Shiral. I certainly don't want to replace my gear at this moment as they continue to give me a lot of satisfaction. I know what you are saying is probably true, but still have a little problem understanding the consequences -- for not being technical savvy enough. So what you are saying is the signal from one board intercepts the other and then sends itself into the second board's data bank? That's how I understand your reply. If that's not what you meant, could you elaborate a little more? Thanks, Shiral.

Cubistone,

The idea you've got from what I said is right. It may not go all the way into the data bank though. It might damage the output stage of the keyboard.

Beyond the digital electronic guts of the keyboard, which includes the data banks, there is an analog output stage that should include a pre-amp. As far as I understand, this is the part the faces this potential damage.

As far as I understand, if both keyboards are built with roughly the same output specifications (impedance, voltage, etc..) , this may not be a problem, but I think it will still deteriorated the quality of the outputs of the keyboards.

Hope this helps.

Shiral

Shiral,

The keyboards now have their separate inputs -- Tape 1 and Tape 2. I just don't want to take any risk of sending them to the repair shop. So they are happily playing along in their own realm right now. Of course, the down side to this is that I cannot be playing both boards at the same time, and have to lean over and press an extra button on the amp when switching is needed (as if I don't have enough to keep my hands busy.)Thank you for sounding the warning. I think it's time for a trip to GC to pick up a bargain-priced Behringer. A little money spent now may save a bunch later on. Thanks very much. I surely appreciate your input.

The little 8-channel Behringer is a real winner. Less than $100. and it works great.
DonM