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#1844487 - 02/14/12 01:06 PM PX-130 mod - line in
JoeyIsFunny Offline
Full Member

Registered: 06/14/10
Posts: 178
Last night I opened my px-130 (easier than I thought) and wired up a jack for the left and right speakers for use as a line in. Basically it was just a mod to use the built in speakers with my stereo amp. I was frustrated with the sound I was getting with Pianoteq through my hifi speakers (Polk R50s). I know that the px-130 sounds are replicated better through the built in speakers (dont ask me how, must be the type of speaker and its response), so I figured Pianoteq might sound good through them as well.

Anyway, I got it wired up and hooked it up to my stereo, but the sound was horrible. I had huge distortion even at low volume. I switched back to the polks and the quality was fine. Possibly an impedance mismatch? I was completely surprised and baffled. Any ideas why it sounded so bad? The speakers in the piano are fine, they arent blown.

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#1844512 - 02/14/12 01:45 PM Re: PX-130 mod - line in [Re: JoeyIsFunny]
MacMacMac Offline
3000 Post Club Member

Registered: 09/24/09
Posts: 3667
Loc: North Carolina
Why? Because keyboard speakers are just a small step up from those found in $20 clock radios. That is, one step up from junk.

Your Polk R50s are better than the speakers found in any keyboard.

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#1844549 - 02/14/12 02:47 PM Re: PX-130 mod - line in [Re: JoeyIsFunny]
sullivang Offline
2000 Post Club Member

Registered: 07/05/09
Posts: 2100
Loc: Sydney, Australia
It's also possible that some EQ has been applied to make the internal sounds sound as good as possible. If so, you are bypassing that EQ, and if you apply your own EQ, it might help. I have the PX-330, and I too think the internal sounds sound good through the speakers. (not fantastic, of course)

Greg.

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#1844562 - 02/14/12 03:03 PM Re: PX-130 mod - line in [Re: sullivang]
JoeyIsFunny Offline
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Registered: 06/14/10
Posts: 178
Originally Posted By: MacMacMac
Why? Because keyboard speakers are just a small step up from those found in $20 clock radios. That is, one step up from junk.

Your Polk R50s are better than the speakers found in any keyboard.


Oddly these internal speakers handle quite a bit of volume from the px-130 quite well. At LOW volume with the stereo amp, there was unacceptable and harsh distortion. Something doesnt make sense... Of course the R50s are better speakers, but when the internal (and Pianoteq) sounds are pumped through them (even with EQ) I just cant get it to sound right which is why I tried Pianoteq through the internals.

Originally Posted By: sullivang
It's also possible that some EQ has been applied to make the internal sounds sound as good as possible. If so, you are bypassing that EQ, and if you apply your own EQ, it might help. I have the PX-330, and I too think the internal sounds sound good through the speakers. (not fantastic, of course)

Greg.


Yes this is possible, but is unrelated to the distortion I was experiencing. LOUD pops and crackles. Its a shame because I know that Pianoteq would sound fairly good through them!


Edited by JoeyIsFunny (02/14/12 03:03 PM)

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#1844573 - 02/14/12 03:27 PM Re: PX-130 mod - line in [Re: JoeyIsFunny]
sullivang Offline
2000 Post Club Member

Registered: 07/05/09
Posts: 2100
Loc: Sydney, Australia
I hadn't noticed your comment about the distortion. Not sure what's causing that. Very interesting!

Greg.

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#1844587 - 02/14/12 03:49 PM Re: PX-130 mod - line in [Re: JoeyIsFunny]
EssBrace Online   content
2000 Post Club Member

Registered: 12/01/09
Posts: 2325
Loc: Suffolk, United Kingdom
Are you ouputting signal from your (hi-fi) amp at line level (eg, tape out) or through speaker cables, ie, an amplified signal? If the latter, you are feeding an amplified signal into the Casio and although I don't know where and how you've wired your new input jacks it might be that the Casio is trying to amplify that signal before it gets to the speakers? In which case you are overloading the input into the Casio's onboard amp.
_________________________
Yamaha CP1

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#1844591 - 02/14/12 03:59 PM Re: PX-130 mod - line in [Re: EssBrace]
JoeyIsFunny Offline
Full Member

Registered: 06/14/10
Posts: 178
Originally Posted By: EssBrace
Are you ouputting signal from your (hi-fi) amp at line level (eg, tape out) or through speaker cables, ie, an amplified signal? If the latter, you are feeding an amplified signal into the Casio and although I don't know where and how you've wired your new input jacks it might be that the Casio is trying to amplify that signal before it gets to the speakers? In which case you are overloading the input into the Casio's onboard amp.


Well, I wasnt sure where to tap into the board to get the jack wired before the amp, so I just wired directly to the speakers. 2 wires for left, 2 wires for right - these went into the stereo amp like you would use any other speaker. This may not be the correct way it should be done, perhaps I bypassed the filter/crossover (if any) which was overloading the speaker?


Edited by JoeyIsFunny (02/14/12 04:08 PM)

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#1844607 - 02/14/12 04:17 PM Re: PX-130 mod - line in [Re: JoeyIsFunny]
EssBrace Online   content
2000 Post Club Member

Registered: 12/01/09
Posts: 2325
Loc: Suffolk, United Kingdom
Mmm. Not sure. In theory if you are just driving the speakers from your hi-fi amp then I don't really understand why you are getting such trouble with it. But something must be wrong...
_________________________
Yamaha CP1

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#1844725 - 02/14/12 07:26 PM Re: PX-130 mod - line in [Re: JoeyIsFunny]
maurus Offline
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Registered: 05/21/11
Posts: 753
Well if I understand correctly you did not disconnect the PX 130's internal amp from its speakers. In this case the signal from your amp not only goes to the speakers, it also goes 'backward' into the circuitry of the keyboard. This can cause all kinds of things, including distortion.
_________________________
Shigeru Kawai SK-2, etc.

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#1845132 - 02/15/12 09:27 AM Re: PX-130 mod - line in [Re: maurus]
JoeyIsFunny Offline
Full Member

Registered: 06/14/10
Posts: 178
Interesting, I may try again and disconnect the speakers from the internal amp. Are you just speculating here, or do you know this from experience? Why Im asking this is because I had the internal sounds turned off, so nothing should have been in the amp circuit of the piano...

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#1845170 - 02/15/12 10:15 AM Re: PX-130 mod - line in [Re: JoeyIsFunny]
MacMacMac Offline
3000 Post Club Member

Registered: 09/24/09
Posts: 3667
Loc: North Carolina
You're feeding two power amplifiers into a speaker.
The first one is the piano's internal amplifier.
The second one is your modification, feeding in the signal from an external amplifier.

You should never do that.

Instead, feed a line-level signal into the piano's line-in (or aux-in) input.
If you piano doesn't have a line input, then you're out of luck.

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#1845241 - 02/15/12 11:57 AM Re: PX-130 mod - line in [Re: JoeyIsFunny]
gvfarns Offline
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Registered: 04/16/07
Posts: 3474
Loc: Pennsylvania
Since your speakers are far better than your piano's speakers and your amp is probably far better than the piano's amp, a more fruitful endeavor would be to try and make things sound better through your hi fi than to force software piano sounds into your onboard speakers.

Interesting experiment, though.

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#1845255 - 02/15/12 12:17 PM Re: PX-130 mod - line in [Re: JoeyIsFunny]
maurus Offline
500 Post Club Member

Registered: 05/21/11
Posts: 753
@joey: I never tried this with a DP but write as someone who has spent years with fiddling around with electronics, amps, speakers, etc. MacMacMac is absolutely right: Either feed a line level signal into a line-in input of the DP, or physically disconnect the speakers from the internal amp and connect them to your external amp instead. I don't see a lot of sense in trying the latter, though (see gvfarns' post).
_________________________
Shigeru Kawai SK-2, etc.

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#1845429 - 02/15/12 04:31 PM Re: PX-130 mod - line in [Re: maurus]
JoeyIsFunny Offline
Full Member

Registered: 06/14/10
Posts: 178
Originally Posted By: MacMacMac
You're feeding two power amplifiers into a speaker.
The first one is the piano's internal amplifier.
The second one is your modification, feeding in the signal from an external amplifier.

You should never do that.

Instead, feed a line-level signal into the piano's line-in (or aux-in) input.
If you piano doesn't have a line input, then you're out of luck.


Well, I had pressed the function on the piano which cuts the internal sounds from going to the speakers, so there should have been no internal signal to the speakers at that point. There is NO line-in on the PX-130, which is why I was trying to mod it to get one.

Originally Posted By: gvfarns
Since your speakers are far better than your piano's speakers and your amp is probably far better than the piano's amp, a more fruitful endeavor would be to try and make things sound better through your hi fi than to force software piano sounds into your onboard speakers.

Interesting experiment, though.


(See above towards top) Ive tried this many times, and while the frequency range is more dynamic with my hi-fi system, the sound is just not "right" to me. I cant get it to sound full. Its like the on board speakers are more midrange heavy and do a better job there. Sure they are lacking in the highs and lows, but the midrange is where it really counts.

This is why I was so intent on hearing pianoteq through the on board speakers.

Originally Posted By: maurus
@joey: I never tried this with a DP but write as someone who has spent years with fiddling around with electronics, amps, speakers, etc. MacMacMac is absolutely right: Either feed a line level signal into a line-in input of the DP, or physically disconnect the speakers from the internal amp and connect them to your external amp instead. I don't see a lot of sense in trying the latter, though (see gvfarns' post).


I think I may try this though, and if it works Ill wire in a switch for switching the speaker between the internal amp and the line in jack.


Edited by JoeyIsFunny (02/15/12 04:32 PM)

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#1845442 - 02/15/12 04:43 PM Re: PX-130 mod - line in [Re: JoeyIsFunny]
maurus Offline
500 Post Club Member

Registered: 05/21/11
Posts: 753
OK try it and let us know how it went, good luck!
_________________________
Shigeru Kawai SK-2, etc.

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#1845445 - 02/15/12 04:47 PM Re: PX-130 mod - line in [Re: JoeyIsFunny]
MacMacMac Offline
3000 Post Club Member

Registered: 09/24/09
Posts: 3667
Loc: North Carolina
Originally Posted By: JoeyIsFunny
I had pressed the function on the piano which cuts the internal sounds from going to the speakers, so there should have been no internal signal to the speakers at that point.
That doesn't matter. The piano amplifier is still connected to the speakers.

So, you're still connecting the output of your external amplifier to the output of the piano's amplifier. Bad! You're risking damage.

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#1845736 - 02/15/12 11:22 PM Re: PX-130 mod - line in [Re: JoeyIsFunny]
JoeyIsFunny Offline
Full Member

Registered: 06/14/10
Posts: 178
Well I opened the PX-130 back up and left it powered OFF this time. I used alligator clips to wire the internal speakers to the stereo, and played a pianoteq recording through it. It worked!!! So the internal amp WAS the problem after all. THANK YOU FOR THE TIPS, Im sorry I doubted you!

I dremeled a couple 3/4" holes in the back of the piano so that I can wire up some switches. I have the stereo wires going in there for now during testing. Ill try to get at least some pics and possibly a video soon if I can.

Im sure you're wondering how it sounds.... Well, not bad to be honest! The bass is definitely lacking, as well as the crystal clear highs, but I EQ'd it and it sounds much better. Im thinking of using the sub from my logitech 2.1 speakers and having it handle the bass, then EQ the internal speakers more for the mids/highs. The only problem is the "ringing" that you get with speakers housed in plastic, but I can overlook it for now. Its not the best sounding, but its really not bad and sounds more realistic than the internal sounds of the PX-130.

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#1845738 - 02/15/12 11:27 PM Re: PX-130 mod - line in [Re: JoeyIsFunny]
gvfarns Offline
3000 Post Club Member

Registered: 04/16/07
Posts: 3474
Loc: Pennsylvania
I'm impressed, both with you willingness to tear into this stuff and your ability to make it work. Way to experiment!

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#1846384 - 02/16/12 08:35 PM Re: PX-130 mod - line in [Re: JoeyIsFunny]
sullivang Offline
2000 Post Club Member

Registered: 07/05/09
Posts: 2100
Loc: Sydney, Australia
Originally Posted By: JoeyIsFunny
Well I opened the PX-130 back up and left it powered OFF this time.


Glad you got it working, however if you're still leaving the speakers connected to the PX-130 internals, that's still wrong - you should disconnect the speakers from the PX-130 electronics if at all possible, even though you are turning it off.

Greg.

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#1846467 - 02/16/12 11:10 PM Re: PX-130 mod - line in [Re: sullivang]
JoeyIsFunny Offline
Full Member

Registered: 06/14/10
Posts: 178
Originally Posted By: sullivang
Originally Posted By: JoeyIsFunny
Well I opened the PX-130 back up and left it powered OFF this time.


Glad you got it working, however if you're still leaving the speakers connected to the PX-130 internals, that's still wrong - you should disconnect the speakers from the PX-130 electronics if at all possible, even though you are turning it off.

Greg.


Yes I understand, this was just for quick testing purposes. Im going to wire in a jack and switch soon, Ill update when its completed.

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#1846524 - 02/17/12 01:00 AM Re: PX-130 mod - line in [Re: JoeyIsFunny]
JoeyIsFunny Offline
Full Member

Registered: 06/14/10
Posts: 178
This is almost comical in a tragic and very sad sort of way... but since I finished testing, I hadnt attempted to turn the piano on and play it normally without the wires attached until just a minute ago. When I hit the power button.... NOTHING. I think I broke the poor thing!

I have verified 12VDC at the AC/DC adapter output, so the problem is definitely inside the piano. A couple of you had mentioned it being bad that I was putting power to the speakers externally without removing the wire from the speaker to the onboard amp, even though the piano was unplugged and off. Im wondering if this could have affected it so that it wont even turn on now???

frown I wonder how much a replacement board costs!? Maybe $100?

EDIT: I just checked the power switch, and the 2 wires soldered to it are measuring as an open circuit in both the on and off position. I shorted them together, but it didnt do any good. Im confused by this... the switch should short the 2 wires together right?

EDIT #2: The switch is fine, I checked it again. Must have been the meter I was using.


Edited by JoeyIsFunny (02/17/12 07:14 PM)

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#1846563 - 02/17/12 03:43 AM Re: PX-130 mod - line in [Re: JoeyIsFunny]
maurus Offline
500 Post Club Member

Registered: 05/21/11
Posts: 753
It seems you are learning electronic tinkering the hard way.

At this point there remains only one advice: Please get someone in who knows what s/he is doing. You might increase the damage already done if you are ignoring what you are doing. Please take this advice seriously. You should have listened more closely to what we were saying before.
_________________________
Shigeru Kawai SK-2, etc.

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#1846633 - 02/17/12 08:53 AM Re: PX-130 mod - line in [Re: maurus]
JoeyIsFunny Offline
Full Member

Registered: 06/14/10
Posts: 178
Originally Posted By: maurus
It seems you are learning electronic tinkering the hard way.

At this point there remains only one advice: Please get someone in who knows what s/he is doing. You might increase the damage already done if you are ignoring what you are doing. Please take this advice seriously. You should have listened more closely to what we were saying before.


I always learn things the hard way, Im bull-headed like that. I did take your advice seriously at first, I thought the problem was having the unit powered on while testing, so I turned it off and unplugged it. I didnt think current on the circuit would be a problem at that point, but I guess I was wrong.

Does anyone have any input about my switch question in blue above?

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#1846647 - 02/17/12 09:35 AM Re: PX-130 mod - line in [Re: JoeyIsFunny]
spanishbuddha Online   content
2000 Post Club Member

Registered: 11/08/09
Posts: 2234
Loc: UK
Originally Posted By: JoeyIsFunny

Does anyone have any input about my switch question in blue above?

Yup that's how single pole switches work, if that's what it is. Maybe you've blown a fuse in the power supply circuit, hopefully, or externally. Nice and easy to fix. Need to check for damage first, obvious signs of burnt wires or conductors or components. Is the unit completely dead, no lights, etc?

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#1846668 - 02/17/12 10:05 AM Re: PX-130 mod - line in [Re: spanishbuddha]
JoeyIsFunny Offline
Full Member

Registered: 06/14/10
Posts: 178
Originally Posted By: spanishbuddha
Originally Posted By: JoeyIsFunny

Does anyone have any input about my switch question in blue above?

Yup that's how single pole switches work, if that's what it is. Maybe you've blown a fuse in the power supply circuit, hopefully, or externally. Nice and easy to fix. Need to check for damage first, obvious signs of burnt wires or conductors or components. Is the unit completely dead, no lights, etc?


I smell no burnt electronics, I see no fried components or wires... I dont see any fuses though, any idea where one might be? You are correct, no lights, absolutely nothing.

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#1846696 - 02/17/12 10:53 AM Re: PX-130 mod - line in [Re: JoeyIsFunny]
gvfarns Offline
3000 Post Club Member

Registered: 04/16/07
Posts: 3474
Loc: Pennsylvania
Wait, I'm a little confused. Does the piano not work at all or do the onboard sounds just not work? I thought you were using it to play pianoteq just a bit ago. If you can still do that it may not be much of a loss. Or were you just playing pianoteq recordings?

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#1846701 - 02/17/12 10:58 AM Re: PX-130 mod - line in [Re: gvfarns]
JoeyIsFunny Offline
Full Member

Registered: 06/14/10
Posts: 178
Originally Posted By: gvfarns
Wait, I'm a little confused. Does the piano not work at all or do the onboard sounds just not work? I thought you were using it to play pianoteq just a bit ago. If you can still do that it may not be much of a loss. Or were you just playing pianoteq recordings?


Yeah, earlier I wrote:

"Well I opened the PX-130 back up and left it powered OFF this time. I used alligator clips to wire the internal speakers to the stereo, and played a pianoteq recording through it."

I was just playing recordings since I had kept the piano powered off in a futile attempt at preventing damage. I then removed all my wiring and went to play the piano as it was meant to be played, and it wouldnt even turn on.

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#1846708 - 02/17/12 11:16 AM Re: PX-130 mod - line in [Re: JoeyIsFunny]
anotherscott Online   content
3000 Post Club Member

Registered: 02/20/10
Posts: 3076
First, to expand on what has been said above, you can't connect two amplifiers to the same speaker at the same time. Since signals don't know when to "stop," without some kind of circuitry to prevent it, you would essentially indirectly be simultaneously wiring the output of one amplifier to the output of another. (And I haven't a clue what you're doing to the impedance...)

But also, when you *disconnect* wires between an amplifier and a speaker, as when you want to disconnect the Casio's internal amplifier from its speakers, you need to disconnect the wires on the *amplifier* side, not the speaker side. Otherwise the amplifier may attempt to deliver its powered signal into the wires that aren't going anywhere, and the amp is likely to ultimately overheat and fail. At least this was the case with amps I worked with many years ago. Amps can be designed to not let this happen, but I wouldn't assume that that would be the case here, as they would never anticipate this kind of operation, since the connection between amp and speaker is not normally user-accessible. If this is what you did, hopefully, there's a fuse in there somewhere that prevented more significant damage.


Edited by anotherscott (02/17/12 11:18 AM)

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#1846778 - 02/17/12 01:17 PM Re: PX-130 mod - line in [Re: anotherscott]
JoeyIsFunny Offline
Full Member

Registered: 06/14/10
Posts: 178
Well I just spoke with Casio and its $46 to replace that main board. There is only one licensed Casio repair facility in GA, and they just so happen to be located less than an hour away from me. I called them (Wizard Electronics in Marietta GA) and spoke with a man (cant remember his name), but MY GOD he was a F***ing A**hole. Never in my life have I experienced such rude and impatient customer service.

First he tells me you pay an initial $60 for the first hour of work plus the cost of parts. Then he tells me that its $80 an hour. So I say something like "so Im looking at around $100 if its done in an hour?" And he would refuse to answer, then proceeds to tell me there is a 2 hour minimum work time!!! I balked at that, and he said it was due to the fact that these pianos are "sooooo hard to get into". I told him I can get into mine in 5 minutes tops and that I could bring it in all opened and ready to go. He said he would refuse to accept it in the condition and it must come in fully assembled. I politely called bullsh*t and he basically hung up on me. Wow. Id do it myself, but the main board has a cable that is soldered to the volume knob board, there is no easy connector to pull out. frown

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#1846794 - 02/17/12 01:37 PM Re: PX-130 mod - line in [Re: JoeyIsFunny]
voxpops Online   content
2000 Post Club Member

Registered: 03/20/07
Posts: 2911
Loc: Oregon
I suggest you order the board and look around locally for a competent electronics expert. There's usually someone who will provide good service at a sensible price.

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