Ideas for a "keyboard speaker" - diyAudio
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Old 12th June 2009, 02:07 AM   #1
ChrisA is offline ChrisA  United States
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Default Ideas for a "keyboard speaker"

I'm just looking for ideas. Hopefully stuff I would not have thought of
OK another "which driver?" question... But this time I have some very specific requirements

I want to build a stereo pair of "keyboard speakers" to be used with an electronic keyboard. Mostly the keyboard will be playing a "grand piano" tone. What I want is to cover the range in frequency and loudness of a real piano. They can go down to about 30Hz. These speakers will be driven with a small stereo tube based amp. Not a lot of power. I only need to "cover" a small venue, 30 foot square max. Real pianos play up to about 90db give or take.

What's different between this and a home stereo speaker is that it is only reproducing one instrument and I don't care about "sound stage." I will place the speakers on a real stage and the listener should hear the the sound is coming from the speaker location. In a way this is like a hi-fi version of a Guitar speaker in that they to NOT reproduce sound, they are the original source of the sound. They only have to do one thing well, piano. No female vocals or whatever. (But then pianos do cover the full range of human hearing)

Physically they need to be transportable smaller is better than larger. And cost IS an issue

What got me stared was one night I was practising at home and playing some low chords with left hand and thought that the little speakers Roland used don't really sound convincing. So I tried an experiment and connected the keyboard to my Fender bass amp. (Bass guitar plays in the same range as the low end of piano.) What a difference! It was like adding a sub-woofer. OK it was adding a sub-woofer. the highs came out over the Roland's built-in speakers and the lows over the fender. I was only using a little 25 watt bass practice amp, but it's an amp and speaker designed for bass.

Now if only I could only put the whole thing together and with better sound quality.
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Old 12th June 2009, 02:28 AM   #2
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trying to get our Yamaha keyboard to sound like her music teacher's piano, I connected it to my guitar amp - that worked well, but you have to get the eq right. It is a 50W amp with a 12" speaker, and I think you'll need something around that size minimum. A small tube stereo amp isn't the way to go - SS and more power will give you reliability and headroom for that realistic sound. As far as speakers go, you probably need a small 2-way PA design, guitar speakers are too coloured.
FWIW You'll probably find it's cheaper to buy a small combo amp for keyboards (Behringer?) than to build.
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Old 12th June 2009, 05:26 AM   #3
ChrisA is offline ChrisA  United States
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Have you ever listened to a Behringer combo amp? It sounds like an amp.

I'm looking for a sound system that removes the "electronic" sound. I'm thinking about a tube amp and a speaker system tuned for piano

I tried the guitar amp too. My Roland keyboard has truly horrible guitar tones. As an experiment I connected the keyboard's line out to a Boss distortion peddle and then sent that to my son's guitar amp. Finally a believable (classic rock) guitar sound.

I got better grand piano sound with my bass amp. eq'd with bass up full and the mid and treb. to 0. That combined with the roland's speakers sounds ok.

Back to my question: What speaker would be best for piano?
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Old 12th June 2009, 06:25 AM   #4
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something like this:

http://www.visaton.com/en/bauvorschl...5_h/index.html
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Old 12th June 2009, 06:54 AM   #5
ChrisA is offline ChrisA  United States
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Thanks,

That has more power than required and not enough bass. The low "A" is 26Hz but is rarly used. I think I need to be flat to 30Hz and mid 90's db sound is loud enough.
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Old 12th June 2009, 07:20 AM   #6
dangus is online now dangus  Canada
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I suspect that a real piano mainly puts out harmonics of 30 Hz. At least a real piano. So 60 Hz may be a more reasonable cut-off to design for.

How about trying a Behringer (or other "imported") 12"/horn or 15"/horn powered speaker? One that's intended for use as a monitor or PA speaker, not a "musical instrument" speaker.
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Old 12th June 2009, 06:27 PM   #7
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Chris A,

Need to be more specific, for example basic things like HWD and max weight, current gear to be used with the system,

For example what is the budget, why do you need a stereo pair? will you be able to seperate the speakers to create a panning effect or would you like a single stereo cabinet?

Using a 30watt tube amplifer is a bad idea so just forget that because its messing up the recomendations.

You may need a 95db average sound so if your want realistic piano sound you will likely need a system that can do a minimum of 105db for a short time without getting messy.

I agree a Behringer is and unlikely solution, but "Cost is an issue" means ?

Do you want to build this speaker? Or assemble commercially available products?

Just items you could contribute to get better advice and more participants,
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Old 12th June 2009, 06:33 PM   #8
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How are the acoustics of the venue and how is the seating arranged? And the budget?
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Old 12th June 2009, 09:34 PM   #9
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I think the OP is about to find that PA- sound reinforcement is not HiFi writ large, it's a completely different ball game...
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Old 12th June 2009, 11:37 PM   #10
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Also I really don't think that using "Stereo" speakers has any real benefit over one good mono box.

If you have a read thru the "LDC" you can see a basic spec for a piano speaker on page 226, 12inch bass/6inh mid and a horn tweeter.

I'd go one bigger with 2 * 12s or 1*15/18 coupled with 8inch mid and a good horn.
Nice experiment but get a decent Pro amp to start with like the small Yamaha, you really do need that sort of grunt for the bass octaves
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