Digital piano cabinet enclosure build

In an effort to get a more natural room-filling resonant sound out of my digital piano, I've decided to build a large cabinet and have some fun testing out different speaker positions and mount types to see if I can come up with something that sounds pleasant.

The cabinet pretty huge, I wanted it to almost be like the cabinet of an upright piano. This may be a terrible idea, but I figured possibly mounting the speakers completely enclosed inside the cabinet might help replicate the omnidirectional resonant sound of a piano. Either that, or use the side/back walls of the cabinet as the baffles (another option being to make individual enclosures for the speakers and mount them with the walls acting as the rear panel of the enclosure, and make it an open rear baffle).

I've messed around with some simple DIY speaker stuff in the past and understand the basics of design, but I'm definitely in need of some direction or advice here. I currently have a couple 8" midrange (90 - 10k) speakers that I'm beginning to test with, and had planned on making it a 2 way 4 speaker system with woofers and midranges, but after some more thought I feel it might be better to just keep it simple and use some full range drivers sans-crossovers, possibly one of these:

Dayton Audio - PA130-16 5" Full-Range PA Driver 16 Ohm

Dayton Audio - PS180-8 6-1/2" Point Source Full-Range Neo Driver

Amazon.com: Visaton BG20-8 8" Full-Range Speaker with Whizzer Cone 8 Ohm: Parts Express

Here are some pics of the cabinet, I plan on making some short legs to lift it up a foot or so, had some idea to open up the bottom some for more of an airy sound. Plenty of space for testing and mounting! :D

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(I know this is terrible speaker placement, but it was fun to do a quick first test and see the response. Also, I wont be using 1/4" MDF for the final baffles, don't worry)

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I expect to have to do A LOT of trial and error, and probably some frequency response measurements with various mounting locations. But any insight or ideas would be greatly appreciated.
 
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I've got a visiton BG17 whizzer cone driver. Pretty decent mid range sound in a taped up cardboard box 8"x8"x18" with a bass reflex port in the back to boost up bass response. Listening to 1940sradio.com on it now, in my kitchen.
You've got enough length to make a good bass reflex path in that box but you may need some sort of tube to establish the bass reflex action. I've read about 31" tube 3" diameter over on speaker construction thread.
Pianos go 28 hz to 15 khz , the good ones anyway. The **** yamaha consoles everybody buys now have no highs, probably stop at 8 khz. Most people are deaf up there anyway, that's why they think a Yamaha is so good. So anyway, you may need a tweeter if your hearing goes above 7k. Depending on the quality of your digital sim. I found a Peavey RM22 driver & horn on ebay for $75 if one of mine ever blows. Look around, you might find one too. 1" horns don't cross over as smoothly to 15", lots of 1"+15" speakers sold.
When I'm playing piano CD's/LP's on material I can't play on my Steinway console, I use a pair of Peavey SP2-XT speakers, with 15" woofers & 2" horn. +- 3 db 54 hz to 14.5 khz (where my hearing stops). Best sounding piano reproduction I've heard. Which is not saying much in this flyover state. Nobody owns magnaplanars around here, I'd have to travel to a coast to hear some.
Remember with your plywood box, the more expensive pianos with real highs had a spruce backboard extensively shaved down to let the highs out. Probably had a lot of failures of the wood at the factory which is why that feature was expensive. Think Baldwin Acrosonic. Nicest loud on stage console piano I've ever played. The cheaper the piano, the thicker the wood. I've got a $50 Wurlitzer spinet piano in the trailer out at my summer camp; it sounds decent with the top & front taken off. Bad as it sounds, it keeps my hands in practice in the summer.
Remember a real piano has to be a few inches out from a hard surface wall for the sound to develop & fill the room. Or the back has to face the audience, which is visually boring.
 
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Fender Rhodes was the best fake piano I met. Four 10" speakers on a box a little smaller than a spinet. Yes, the speakers on the outside just like the Sound Board of an upright is exposed in back.


Oh nice, I suppose using the cabinet as just a full stack on its side could work haha.


I've got a visiton BG17 whizzer cone driver. Pretty decent mid range sound in a taped up cardboard box 8"x8"x18" with a bass reflex port in the back to boost up bass response. Listening to 1940sradio.com on it now, in my kitchen.
You've got enough length to make a good bass reflex path in that box but you may need some sort of tube to establish the bass reflex action. I've read about 31" tube 3" diameter over on speaker construction thread.
Pianos go 28 hz to 15 khz , the good ones anyway. The **** yamaha consoles everybody buys now have no highs, probably stop at 8 khz. Most people are deaf up there anyway, that's why they think a Yamaha is so good. So anyway, you may need a tweeter if your hearing goes above 7k. Depending on the quality of your digital sim. I found a Peavey RM22 driver & horn on ebay for $75 if one of mine ever blows. Look around, you might find one too. 1" horns don't cross over as smoothly to 15", lots of 1"+15" speakers sold.
When I'm playing piano CD's/LP's on material I can't play on my Steinway console, I use a pair of Peavey SP2-XT speakers, with 15" woofers & 2" horn. +- 3 db 54 hz to 14.5 khz (where my hearing stops). Best sounding piano reproduction I've heard. Which is not saying much in this flyover state. Nobody owns magnaplanars around here, I'd have to travel to a coast to hear some.
Remember with your plywood box, the more expensive pianos with real highs had a spruce backboard extensively shaved down to let the highs out. Probably had a lot of failures of the wood at the factory which is why that feature was expensive. Think Baldwin Acrosonic. Nicest loud on stage console piano I've ever played. The cheaper the piano, the thicker the wood. I've got a $50 Wurlitzer spinet piano in the trailer out at my summer camp; it sounds decent with the top & front taken off. Bad as it sounds, it keeps my hands in practice in the summer.
Remember a real piano has to be a few inches out from a hard surface wall for the sound to develop & fill the room. Or the back has to face the audience, which is visually boring.


Interesting point about the thinned wood to let the highs through. I definitely noticed how closed in the sound was in my initial test with the lid closed. This is why I was thinking about putting ports in or partially opening the side/rear baffles. I would definitely keep it 4-6" from the wall, especially if the speakers are going to face backwards at all. I'm considering just using much thinner plywood for the back with some bracing, now. :scratch:
 
Interesting point about the thinned wood to let the highs through. I definitely noticed how closed in the sound was in my initial test with the lid closed. :scratch:
With speakers you can cut holes to let the sound out. With pianos the strings have to be held in by a strong wood box. BTW mice like to build nests in pianos, one reason the wood box needs to be totally closed. I found out the hard way with my Wurlitzer out in the open fields with hot & cold running mice. Fortunately they didn't chew up the felt hammers. Mice did chew up the wiring in the steel tab box of my Hammond organ, though. After I replaced the wires I taped tin can parts over all the wire harness ports. I'm thinking of buying a steel container or old stainless Greyhound to stay in out there too keep the mice, racoons, groundhogs, and snakes out of my living space. Racoons can smell a diet orange soda through partical board and chew their way right through the floor in an hour. Chewed the top off the 2 liter bottles too, made a big mess. No more partical board housing for me. I like watching the wildlife out there when they stay outdoors where they belong.
 
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With speakers you can cut holes to let the sound out. With pianos the strings have to be held in by a strong wood box. BTW mice like to build nests in pianos, one reason the wood box needs to be totally closed. I found out the hard way with my Wurlitzer out in the open fields with hot & cold running mice. Fortunately they didn't chew up the felt hammers. Mice did chew up the wiring in the steel tab box of my Hammond organ, though. After I replaced the wires I taped tin can parts over all the wire harness ports. I'm thinking of buying a steel container or old stainless Greyhound to stay in out there too keep the mice, racoons, groundhogs, and snakes out of my living space. Racoons can smell a diet orange soda through partical board and chew their way right through the floor in an hour. Chewed the top off the 2 liter bottles too, made a big mess. No more partical board housing for me. I like watching the wildlife out there when they stay outdoors where they belong.


Wow what a roller coaster. :p If I use this cabinet as an actual speaker cabinet with the drivers mounted to the back wall facing out, would you recommend building internal boxes for them to enclose them a bit more since the cabinet is SO large? Or would they be OK just sort of free floating there on the massive baffle (back cabinet panel)?
 

MAAC0

Member
2010-05-02 10:00 pm
I would build a "fake" Piano scaled to the keyboard and put the keyboard on the keyboard side of the piano. I have seen this done by a friend of mine. You don't need the heavy piano iron, nor You don't need to use heavy or strong wood, but would look good from the aesthetic side of things on a wedding venue or bar for example.... I'm sure You can place there good drivers & amp and the volume of the box will help You with the bass. If You intend to place it and not moving it that's the way to go.
 
Wow what a roller coaster. :p If I use this cabinet as an actual speaker cabinet with the drivers mounted to the back wall facing out, would you recommend building internal boxes for them to enclose them a bit more since the cabinet is SO large? Or would they be OK just sort of free floating there on the massive baffle (back cabinet panel)?
Getting flat frequency response out of a speaker design requires extensive knowledge, measurement, adjustment. I know one trick, long paths from the woofer back cause improved bass response - the bass reflex design. My Peavey SP2-XT are pretty giant boxes @ 32"x31.5"X19", sealed up. No reflex port.
Yes, I would put the drivers on the back to reflect against a hard wall about 6" away. If your tweeter is a lot less powerful you might fire up, but on a high roofed stage that would lose the sound in open space. More details can be learned over on speaker forum from experts. Lots people over there are fascinated by single driver boxes, which I see as okay on strumma strumma singer/songwriter material but totally inadequate at real piano sound. Piano has vast power demand for milliseconds when the hammer hits; nothing else is like it.
I bought speakers package built because my high school buddy's 4 driver speaker pair he built from Allied Radio drivers sounded particularly horrible. Also all that woodwork would make me sneeze, and I have no pickup anymore to haul MDF sheets home.
Take a solo piano CD to a Peavey, JBL pro, or Yamaha dealer to have a listen to a 15+horn PA top. You'll know what the competition can sound like. I used Rudolf Serkin 3 Beethoven Sonatas, the Appasionatta goes all the way up & down the keyboard. The Peavey SP2g speaker is so flat 54-14khz it has a <-20 db Harmonic Distortion spec at 1 W. If the dealer just has PV15's in stock with the 1" horn driver, be prepared to be underwhelmed. Okay for electric guitar & vocals, I guess.
See this thread DIY digital piano speakers
and the other 4 threads about digital piano speakers down at the bottom. Multiway & full range forums. Those guys may know a lot more about building speakers than I do.
 
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Lots people over there are fascinated by single driver boxes, which I see as okay on strumma strumma singer/songwriter material but totally inadequate at real piano sound. Piano has vast power demand for milliseconds when the hammer hits; nothing else is like it.
I bought speakers package built because my high school buddy's 4 driver speaker pair he built from Allied Radio drivers sounded particularly horrible.

Trying to understand what you mean here, are you saying the full range drivers may sound like dog crap in this application? I would probably be using 4 of them, 2 for each channel. No tweeters, as I dont need that much sparkle (I think). This is purely for home use in a fairly small room.

See this thread DIY digital piano speakers
and the other 4 threads about digital piano speakers down at the bottom. Multiway & full range forums. Those guys may know a lot more about building speakers than I do.

I did see a couple of those. These types of setups are always possible, but this project was more about trying to replicate the less point-source sound of an actual piano cabinet on a small budget. Thank you for all the info, I appreciate it!

I would build a "fake" Piano scaled to the keyboard and put the keyboard on the keyboard side of the piano. I have seen this done by a friend of mine. You don't need the heavy piano iron, nor You don't need to use heavy or strong wood, but would look good from the aesthetic side of things on a wedding venue or bar for example.... I'm sure You can place there good drivers & amp and the volume of the box will help You with the bass. If You intend to place it and not moving it that's the way to go.

Good idea! I may try that if/when I get this all finished and am happy with it. This is purely for home use in a fairly small room.
 
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6L6

Moderator
Paid Member
2010-10-22 6:43 pm
Denver, Colorado
Neat project!

I’d mount the speakers on the outside of the box. On the front or back, and on the plywood directly. Resonance is actually going to be your friend. Open and close the lid to help shape the sound. Mounting them inside is going to be muffled and weird, as you’ve discovered.
 
Neat project!

I’d mount the speakers on the outside of the box. On the front or back, and on the plywood directly. Resonance is actually going to be your friend. Open and close the lid to help shape the sound. Mounting them inside is going to be muffled and weird, as you’ve discovered.


Seems like this is the consensus, I'll give it a try. Would you suggest flush mounting the speakers, or will this not really matter for 8" drivers? Should I divide the cab in half internally to separate the L and R channels, or just leave it all open inside? I was thinking maybe I should add some panels or blocks inside to help breakup unpleasant resonances, at least in the corners...
 
Definitely a neat project, perhaps some experimentation with damping materials as well could be helpful.

I'm thinking things like lambs wool (loose fiber), natural animal hair based carpet backing, acousta-stuff and fiberglass.

I'm going to round up a couple of other people to weigh in here with potential ideas.


Yes absolutely, damping materials will make their way into this cab!


Here's a link to an old thread here on the topic of speakers for a digital piano. The thread is 9 years old, long dead, and predates the I&A, but maybe there are some ideas you could use?

DIY digital piano speakers


I had checked that thread, but it's not really the direction I'd like to go.
I'm going to be using the Pianoteq software to generate the sounds, it is some incredible wizardry of modeling software. It has many customizable parameters, so I can also use that to help shape the sound.
 

wintermute

Administrator
Paid Member
2003-08-03 11:43 am
Sydney
Wow what a roller coaster. :p If I use this cabinet as an actual speaker cabinet with the drivers mounted to the back wall facing out, would you recommend building internal boxes for them to enclose them a bit more since the cabinet is SO large? Or would they be OK just sort of free floating there on the massive baffle (back cabinet panel)?

If you have different drivers then they should have their own volumes. A large driver in the same volume as a smaller driver will modulate the smaller driver due to the pressure changes in the box (and to a lesser extent the other way around too).

I've not tried them, but something I have seen on the forum is flooders. In this case you have up firing drivers, these could be your higher frequency drivers and you could mount them on the top of the rear box, with an appropriate grill in place. For lower frequencies, 100Hz and down direction is not important and you could mount driver(s) on the side or back.

I would think that the biggest challenge with getting good sound if the drivers are enclosed, is that the electric piano is set up to provide the right sound with drivers that radiate directly. Putting them inside a wooden box I'm pretty sure is going to sound very muffled. An upright piano is normally open at the back, it is not completely enclosed, and a grand is normally played with the lid open.

Tony.
 
If you have different drivers then they should have their own volumes. A large driver in the same volume as a smaller driver will modulate the smaller driver due to the pressure changes in the box (and to a lesser extent the other way around too).

I've not tried them, but something I have seen on the forum is flooders. In this case you have up firing drivers, these could be your higher frequency drivers and you could mount them on the top of the rear box, with an appropriate grill in place. For lower frequencies, 100Hz and down direction is not important and you could mount driver(s) on the side or back.

I would think that the biggest challenge with getting good sound if the drivers are enclosed, is that the electric piano is set up to provide the right sound with drivers that radiate directly. Putting them inside a wooden box I'm pretty sure is going to sound very muffled. An upright piano is normally open at the back, it is not completely enclosed, and a grand is normally played with the lid open.

Tony.

That was closer to my original idea, but I think I've decided to try to make one of the full range drivers that I listed at the start work. I'm leaning towards the Visaton BG-20. I'd consider a more expensive driver, but since I will possibly be using 4 of these, the cost becomes an issue, and the BG-20 seems to be a fairly good performer.

Since I'll be using identical speakers in the cab, I assume they wont need their own volumes. At least at the individual driver level. Perhaps it would be a good idea to separate the L and R halves of the box since it is a stereo signal, but that will be a very simple test to rig up for A/B testing.

I'm wondering about a small array of identical and closely coupled drivers, perhaps this would be a closer approximation to how a piano launches sound into space?

Maybe a woofer in between in order to extend LF response a bit?

You're getting close to what I've been considering! I'm thinking either two L and two R full range Visaton 8" drivers mounted on the rear wall, or four L and R 5" Dayton Audio full rangers. If I find I need a thicker low end, I could just plop a small powered sub in the cab, or mount a 10" mono fed woofer crossed at like 100Hz to the front wall.
 

AllenB

Moderator
Paid Member
2008-10-18 11:31 am
Why not consider a blend..

On one hand listen to a typical portable sampled piano with good full-range speakers. The samples include the various resonances, reverberations, tone and near standing wave effects of the original piano. Theory says this is reproduction, not production of music so use flat and clean behaving speakers.

However, such an instrument doesn't sound quite right.. It doesn't sound as big in the room, or produce the same tone or spaciousness at mid and higher frequencies.

You could treat this problem like the hi-fi set do, and assuming the samples have stereo information you can ensure your speakers reach low and clean working properly into your room, and after this the sound comes together as intended.

If however the piano is in stereo but without room reverberation information you could go for a speaker that interacts more with the room. Alternatively you could use DSP to add reverb to taste.

Whether this works in a venue is another story. Maybe you don't have much choice where to set up, maybe the space is acoustically large, you may have to bring your own spaciousness..

If you're prepared to get creative, a large cabinet could be your tool of choice. You could use it to get bass at higher levels. You could produce directionally varying reverberation using multiple DSP channels. Add an exciter unit to make the panel a distributed mode speaker like a piano soundboard. Place side and angled firing speakers to project stereo via reflections, or add effects units.
 
The good thing about the piano software I will be using is that the pianos are completely modeled in software, and they include DSP for effects like reverb, chorus, delay, etc, as well as mic placements to simulate different room recording/listening sounds. I think this could definitely help shape the sound. Again this is just for home use, so I can find a solution that works well where I will be playing, and tailor it specifically for that environment.

I like the idea of adding speakers to the side panels. I could put a small driver on each side to help spread out the sound. I'm still wondering if all these drivers would interfere with each other in the cab, being open to the air inside.