Building 50w speaker cabinet with Jensen C12N 50w and want to add a tweeter


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For use with keyboards (and maybe vocals) I am building 50w speaker cabinet with Jensen C12N 50w speaker and want to add a tweeter. I have built into the cabnet a bass reflex enclosure.
I plan on powering the cabinet with a 50w bass amp head.
question 1: Am I crazy?
question 2: What kind or tweeter should I use and how do I wire it?
The 12" 50w speaker is 8 ohm.
The use will be for jamming and recording; not for performance.
 
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If you are using a bass amp to drive the cabinet the quality of the tweeter (other than a cheap one which might burn out) is not a deal breaker. Bass amps typically have a frequency response in a range +/- of 40hz to 4-5Khz. Many 12" (not sure about Jensen) have a range of up to 2Khz. So your tweeter will not reproduce that much of the total frequency response that you will hear. Unless you are a bass player I would opt instead for a full range amplifier that supports a broader frequency response and also then put in a higher quality tweeter, like a compression tweeter. Compression tweeters typically do not come with a coil (acting as a low pass filter) so you need to either put in a crossover or a resistor of some sort to "filter out" the lows from going into the tweeter; if not you'll like blow the tweeter fairly quickly.

cheap horn tweeter

crossover < -- there are many, this is just one example. Source one which best meets your needs
 
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happyrat1

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Speaker design is a science unto itself somewhat akin to witchcraft.

My advice is to google the subject extensively.

If you plan to add a tweeter to an enclosure you'd best find a suitable crossover board for it.

It's not as simple as wiring up a couple of cones in parallel and hooking up an amp.

Do your homework else you will end up watching your time and money go up in smoke :eek:

Gary ;)
 
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I echo the advice given.

I certainly would not supply a 50W speaker with a 50W amp.

That is a recipe for blown speakers, you need headroom to be safe.
 
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Thanks delaware dave, happyrat1, Biggles, and b3manic for the great thoughtful responses.
The C12N speaker was used on some early bassman amps but became a favorite for many styles of guitar.
I've had two of these speakers new in the box for years. I helped a friend build a 30w amp head and cabinet and it's styling and sounds ok. Then spent a year building a guitar around an old telecaster neck and it's now my fav. I know I'm finding my way with this keyboard amp head and speaker cab and it would be a much solider choice to read reviews and buy something together, but I have the bug.
I don't understand frequency response but I'll study up.
I'll also start looking at 30w heads, friendler on the 50w speaker. You mention a full range amplifier that supports a broader frequency response and then put in a higher quality tweeter like a compression tweeter: are you describing a guitar amp head? A lot of what I read seemed to suggest keyboard artists preferred a bass amp to get the low end range of the keyboard which is greater than a guitar.
Thanks for the wise lead an crossover boards for the tweeter(s). I'll read more about it.

Just for fun the speaker cabinet I built from John's pencil sketch, John built the amp head. The acrylic legs were turned by a friend and the naugahyde was applied by Willis Hotrod.
I designed the guitar around an old tele neck and had help routing, soldering and doing the set up from talented buddies.

Thanks for everything,
Dale
 

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Frequency range is the low to high value that you can hear typically measured in Hz cycles. The human ear can hear 20hz to 20Khz. Instruments fall into a relative hz cycle range (audio frequency) that they can reproduce; certain instruments the hz cycle output (loudness of a particular tone) might be emphasized to support the instrument.


Guitar speakers support the guitar audio range frequency and bass heads support a bass's audio frequency response needs. So as I read above you are trying to drive a guitar speaker with a bass head for use with keyboards and vocals. They don't match up, so the results will be sketchy at best and if by some miracle it actually turns out to sound good it is only because you got lucky. I would be hesitant to build a speaker "system" with components that don't match well; your likelihood for success is low. I'd rather do the homework, understand frequency audio range, frequency boost, cabinet structure, quality of components and make an educated design spec. It is somewhat comparable to people who complain that their luxury car doesn't take cornering at fast speeds like their sports car. That's because the suspension on the sports car is vastly different than the suspension on a luxury car. They all have the same components (springs, shocks/struts, ball joints, etc.) but each one is built for a different purposes; the sports car can corner better at high speed because it is stiffer but rides rougher where the luxury car doesn't handle cornering as well but has a much smoother ride. A comparable theory goes toward speaker cabinet building. There is a folded horn design, bass reflex, sealed, etc.. Each one serves a different purpose and each one will yield different results audio results. Also, what should the size of the port be, 2", 3", 4"; how long should the tube be that is inserted in the port, 2", 6", 9"? And this is just the speaker cabinet design. Then there are the components: which type of speaker, what frequency response, what size speakers? So many variables. I've built a few dozen speakers cabinets and sourced components for them over the years; it's indeed a calculated science. Typically the type of speaker cabinet (enclosure) needed and its related specs (port size, tube size, if ported), type of enclosure to be assembled, cubic feet of the enclosure needed to support the speaker is based on the speaker to be used in the system and not the other way around.

This document may help you:


Again, based on what you're doing, bass head into a guitar speaker, and playing keyboards and vocals, the odds of miraculously getting it right are against you. Good Luck....
 
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Thanks delaware dave (and all) for the wise thoughtful time you've given me.
My thinking after your comments is to build two nice 50w guitar cabinets for my Jensens speakers and research a nice small amp/speaker combo for my keyboard.
I can't say thank you enough,
Dale
 

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