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Hi all,I got back into gigging recently. Play keyboards – piano and organ clone rig. Sometimes bass. Rock/jazz/blues for fun mostly. Went looking for a keyboard amp and guess what. Most are crap. Underpowered and expensive too. There’s plenty of great guitar and bass rigs but the offerings for keyboard just didn’t sound that good to my ear. So I’m thinking of building my own setup that should sound better than any commercially available amp. The setup would consist of a rack mixer and power amp with two speaker boxes. My idea is like a hi-end Roland jazz chorus amp. However I’d like to make two boxes – each with a 12” woofer and tweeter. That way I can elect to take one or both depending on the gig/rehearsal. Box size will be around 1.5-2.5 sq ft. I’d like to use neo magnet drivers to keep weight down (not getting any younger). I’ve looked at Bill Fitzmaurice’s dr horns and while they would be the ultimate solution, I don’t have the time nor woodworking skills to construct them. So it’s direct radiators in either closed or vented boxes.
Driver candidates:
Eminence Beta 12 http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=290-408
Eminence Delta 12 http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=290-414
Eminence Delta 12LFA http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=290-416
Eminence Deltalite 12 http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=290-593
B&cC 12HPL76 neo 12 http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=294-680I’m leaning toward the B&C because of its smoother mid response ( the deltalite and most of the eminence drivers have a pretty big peak around 2K which might be fine for a bass and guitar but might make keys sound honky). The Eminence Beta and Delta drivers are lower cost solutions and may be more appropriate if the neo drivers are overkill for this application. On paper the B&C response is flatter in the mids and seems to be a beautifully constructed driver.
Can’t decide on closed or vented. I played around with winisd and it seems that a closed box will help limit cone excursion which may help power handling. Sometimes I may play electric bass through this system so don’t know if that becomes a factor for choosing closed or vented.
I’ll use a piezo tweeter for the top end for simplicities sake. Don’t want to get into horns and compression drivers with crossovers. Not sure what tweeter to use though. There seems to be a lot of 99 cent piezo available but I’m sure that they don’t have the power handling for gigs. Can you guys recommend a piezo for this aplication. Whatever thoughts or opinions you all have on this project is greatly appreciated.
Thanks in advance and ready to spin up the table saw,
Bob
Follow Ups:
Before you build consider the price for everything and purchasing
a cabinet already madeMusicains friend has a sale on cabs currently and consider
a 15" two way instead of a 12" to give you full range for
your keys
You're not going to have any midrange dispersion going from a twelve to a tweeter. They may look good on-axis by they'll beam above 1.2kHz. Go 3 way. Also, go vented. The same mechanism that limits excursion with a sealed cab also kills bass response, and you'll end up with less headroom as it will take twice the power to achieve the same output below 100 Hz.
nt
You forgot the hernia.
And I'm building a single manual spinet chop comprising three chunks, none of which is over 50-60 lbs. A real Hammond that you can carry upstairs by yourself (without superhuman strength or a team of chiropractors.)
Back in the 90's we had a guy with a full size B3 and it was
a 1957 blonde he got from his uncle
Heres how we carried this thing
He purchased two 8ft hand rails (the round dowl type) from a
lumber yard
We stuck a hand rail under each side of the B3 and the legs would
keep them from slipping out the sides
Then four of us would take a section of hand rails on the different
sides and we picked this thing up and carried it
You should have seen guys carrying this thing up and down stairs
as it slid around on the hand rails
UNREAL...we all vowed NEVER again after that stint
The guy finally purchased some dam dollies for the thing
300lbs for a B3Cant beat the sound but the saying is...
"I aint liften that thing"Even in a B3 dolly/cradle with castors
nt
Thanks for your expertise Bill. Vented it is then. I had also toyed with the idea of adding a 6" mid driver to this box. I was persuaded to shelve that idea because all of the commercially available amps use a 12 or 15 with a piezo tweeter. I guess that's one of the reasons they don't really cut it.Any experience with b&c drivers?
Thanks for you thoughts
Bob
B&C is a good driver and so is BeymaI have a pair of montiors with B&C 12" cones and 1" compression drivers
Save yourself alot of grief and go with a compression driver instead
of a peizo
Peizos are great for repelling rodents and bugs but suck for
decent pro audioIMHO
You can go with a small 1"horn and driver with a 12"My only question is with the bandwidth a keyboard uses why would
you want to go with a 12" driver (unless your counting on the mains
to produce your low end) instead of a 15" loudspeaker to give
you more of a full range sound?You can get some decent Emminence compression drivers and horns
at a reasonable price at
"I was persuaded to shelve that idea because all of the commercially available amps use a 12 or 15 with a piezo tweeter."Not from JBL, EV, EAW, Martin or any other builder of quality products. While there's absolutely nothing wrong with piezo tweeters properly employed [I prefer them myself, but I only use them vertically arrayed] a cab that matches a twelve or fifteen and one piezo, or a few horizontally arrayed, is a piece of junk.
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