Hard to find DP Replacement Tweeter

[eblues]

So, I took a $300 chance on a 2000 Korg Concert Ci-9600 with rattly keys (noisy only on release). I read somewhere they have nice action, a bunch of voices and other cool features, and was a $5,000 instrument back in its day. The racket made when releasing the keys was so bad they could be heard over playing at moderate volume... very annoying.

Well, it was a struggle, but I managed to get the key bed out and replace the expensive and/or no longer available lower felt strip with some $7 weatherstripping from Lowe's (an idea I got from YouTube). I'm pleased to report the weather stripping worked surprisingly well at silencing the keys. They are not dead quite (are DP keys ever dead quiet?), but it's quieter than my Casio Privia 160.

I'm not a pianist by any stretch of the imagination, but this Korg does seem to have more sensitive key response, both physically and in volume. It feels a lot different than the Privia, but whether it's more like a real piano? I assume that it must be. I'm very happy with it at the moment... we'll see how long the weather stripping holds up.

During the project, I had keys coming unseated and popping off everywhere, especially when I tried to flip the key bed back right side up, and had a heck of a time figuring out how to hold everything together for reinsertion into the cabinet. Finally, a strip of well positioned masking tape did the trick, and once I figured that out the rest of the job when pretty smoothly.

That is until I accidentally leaned on one of the exposed tweeters inside the cabinet during reassembly (which projects upward into open air inside the cab - monitor speakers?). Dang it! So close to an error free project.

The destroyed speaker is about 2" (5cm), and rated for 16 ohms and 15 watts. That's quite a bit of power for a 2" speaker.

Although the DP seems to sound fine without it, I would replace it if I could do so for a few bucks. Unfortunately, I have not been able to find a suitable speaker of this size and rating. All the 2" speakers I've found so far seem to max out at 2 watts. The speaker just screws face down to the surface of the sound box, so exact size and shape is not an issue.

Anyone know where I can find such a speaker, or something acceptably close? Here's one tip I've learned, Yamaha was/is a major partner of Korg, going back before 2000, and supplied Korg with many mechanical parts.


I didn't realize it until I got it home, but it has a touch screen for selecting voices. The unit seems pretty old for that technology. If the touch sensors fail, I guess I'd be stuck with just the default Piano voice... but since I'll mostly be playing it as a piano anyway, it won't be the end of the world if that happens.

[Tim_at_Jonas]

See if PartsExpress.com or Madisound.com have something that will drop in.

[toodles]

Maybe this: https://www.parts-express.com/grs-ph...8-ohm--270-252

[eblues]

See if PartsExpress.com or Madisound.com have something that will drop in.

Maybe this: https://www.parts-express.com/grs-ph...8-ohm--270-252

Thanks for the suggestions. I looked at both PartsExpress and Madisound. Nothing that is an ideal match. Toodles, the one you linked would be a good fit, except that it's 8 ohms. The original is 16 ohms.

The combination of small speaker with 16 ohm and 15 watt rating, plus tight space for install, and needing to be flush mounted facing the baffle, all add up to a bit of a difficult find.

PartsExpress did have some cheap buyout Samsung TV speakers that are 16 ohm. They're 1 3/8 x 2 3/8 oval, and only 8 watts. But a pair only cost $10 including shipping, so no great loss if they don't work out.

[toodles]

There are not many 16 Ohm speakers made these days--you might have to go with an 8 Ohm unit. Since it will play louder, you could just use an 8 Ohm resistor in series with the speaker and thus cut its output in half. The math then works out that it would play at the same level as if it were a 16 Ohm speaker. Note that the resistor should be rated for the same power as the speaker.

[eblues]

There are not many 16 Ohm speakers made these days--you might have to go with an 8 Ohm unit. Since it will play louder, you could just use an 8 Ohm resistor in series with the speaker and thus cut its output in half. The math then works out that it would play at the same level as if it were a 16 Ohm speaker. Note that the resistor should be rated for the same power as the speaker.

I thought about using a resistor, but when I researched that I found some forum "opinions" out there that suggest adding a resistor is not really the same as having two speakers in series, and that this approach can have a negative effect on crossover circuits. The owner's manual shows a power output of 40 watts x 2. I interpret that to mean the large and small speakers are being driven in pairs by left/right channels and using a crossover. So I put that idea on the back burner.

But since this is more like a secondary system, it might not make that big a difference what I do. Right now, to avoid running the DP with a disconnected speaker I reconnected the bad speaker after stripping off the damaged cone so it wouldn't buzz. Honestly, I'm hard pressed to tell much different between the left and right sides, even getting right up close. The remaining good speaker (of the small pair) on the right side really doesn't seem to have much output. Most of the sound seems to be coming from the 5" down facing main speakers, and the unit sounds fine to my 65 year old, power plant abused ears from a normal playing position.

Still, I like to have things right at a reasonable cost if I can, just because. I'll try those low cost retangular speakers I have coming, and continue to scour the Internet for a proper 16 ohm, 15 watt match.

If not successful, I may end up trying the resistor approach, and see how that works.

I don't like the idea of just using a pair of 8 ohm speakers. This is a 18 year old unit that might not tolerate even a small amount of being overworked. But I still want to do a little more research on this topic. I have read some random forum advice elsewhere that suggests a move up or down by one standard ohm level is not usually a problem.

thanks again for your input!

Other than the self-created issue with the damaged speaker, I'm really happy with this unit for now. everything seems to be working as it should, and having had some time on it now after replacing the lower felt strip, it does feel nicer to play compared to my Casio Privia P-160. And the LCD makes it a lot easier to use the metronome, change the voices, and such. At $300, if it lasts a couple years, I'll feel like I got my money's worth.

[toodles]

A speaker does not have a uniform impedance across the frequency spectrum and so a single resistor is a compromise solution. I suggest it because it is simple and low cost. No, it's not the same as two speakers in series, but it will help balance the woofer and tweeter. Resistors are often used in the tweeter branch of a speaker system to balance the woofer and tweeter. Often this is done by the designer by ear--after having calculated what it "should" be. Speaker design is as much art as it is science. You can probably just use a 10 Watt resistor, since about 80 percent or more of the power is used by the woofer, not the tweeter.

The single resistor will keep the tweeter from drawing too much power.

I should say that there are some speakers which do exhibit consistent impedance across the frequency spectrum, typically ribbon tweeters will do this. In those cases a single resistor is just fine for adjusting volume because the tweeter itself acts like a resistor load. This is one such tweeter: https://www.parts-express.com/beston...eeter--277-114

Note that it is very important to limit low frequency signal for ribbon tweeters to keep distortion low and prevent damage.

[eblues]

Thanks for the additional info. One more question I meant to ask....

On a guitar forum a person was asking about running a 100 watt, 4 ohm tube amp into an 8 ohm speaker. In this case I think the plan was to hook a 100 watt resistor up in parallel. In this discussion, one person suggested that a smaller resistor (I believe he said 40 watt) can just be dangled off one of the speaker terminals (leaving the other end free). Would that work?? Would the resistor soak some power only being attached on one end? My logical but uneducated brain says no, but no one on that forum challenged this suggestion.

[toodles]

No, connecting one lead from a resistor does not create a circuit--no current flows. Otherwise why would all our power wiring use two wires?

[eblues]

10-4, that's what I thought, and I found it odd that no one on that forum challenged this advice.

It was an old thread, which I can't even find it again, otherwise I would have asked for a more detailed explanation.

[eblues]

The 1 3/8 x 2 3/8 retangular Samsung speakers arrived. Darn cute little things, they are. Visibly they have less surface area than I was anticipating compared to the 2" round originals, but....

I did some comparison testing. I installed one of the new speakers, left the "good" original in, and disconnected both main 5" speakers so I could hear what these little monitor speakers were actually putting out. To my surprise, the new speaker had more volume than the original. But even more enlightening, the original speaker distorted badly at about 1/2 volume, which the new speaker did not do. So, perhaps it was a bit of a blessing in disguise that I damaged one of them.

But the truth of the matter is, even the new, somewhat louder speakers put out very little volume compared to the mains, which simply drowned out the little guys. If it were possible to A/B test switch them in and out, that might be the only way to hear any difference with/without them. I mean, I wasn't even able to hear the distortion until I disconnected the mains.

Anyway, the new speakers are installed, the cabinet reassembled and shined up a bit. No more tinkering required. I'll play it till it croaks.

[Kurzweil]

The new speaker is presently louder because it's presenting half the load as the original. You could try using BOTH 8 ohm speakers in series. You wouldn't necessarily even have to cut an opening for #2. This provides the world's best 8 ohm reduction load.

Each would put out slightly less volume (because less current now flows due to the higher load) but you'd be matched up, impedance and power wise. That said, playing it till it (or you) croaks remains an excellent option.

[eblues]

The new speaker is presently louder because it's presenting half the load as the original. You could try using BOTH 8 ohm speakers in series. You wouldn't necessarily even have to cut an opening for #2. This provides the world's best 8 ohm reduction load.

Each would put out slightly less volume (because less current now flows due to the higher load) but you'd be matched up, impedance and power wise. That said, playing it till it (or you) croaks remains an excellent option.

The rectangular Samsung TV speakers I ended up getting cheap are actually 16 ohm, although they're under powered at 8 watts, compared to the originals. Anyway, at 16 ohm, they were drop in replacements. I think they're just louder because either A) the original speakers had gone bad, or B) the new speakers are more efficient, or C) both A and B.

I considered using two 8 ohm speakers per side as an option, if the under powered TV speakers ended up not cutting it.... but I can't detect any distortion.

As an afterthought, Syntaur.com did come back to me a few weeks after I sent my inquiry. They could have ordered the original replacements direct from Korg for about $20 each. Might have done that if they'd responded sooner.