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Amp builders help!

chaunceyjiggson

chaunceyjiggson

Guest
Apr 11, 2012
41
1
#1
I have an acoustic b115 cabinet that now sports a eminence la15850 15" 800w speaker and it's amazing. But... It's only 8 ohms and the high frequency response could be a ton better. It's decent now but I'm definitely pushing my amps highs to get a decent amount now and if like to change that. Is there any way to...

1) make this one cabinet 4 ohm without an extension cabinet
2) expand the high frequency response a good bit

I've been thinking maybe adding one or more smaller speakers wired together to boost the high response if I could squeeze them in there and definitely a new tweeter and crossover. I've also wondered if it's possible to do a double baffle thing like orange does on a cab or two. So any thoughts?
 
#2
You may be better off with a different cab. A budget cab is a budget cab. Nothing wrong with that, but if you aren't happy with what it is, changing it could really be good money wasted. You just aren't satisfied with what that cab has to offer. Why do you want it to be 4 ohms? If it's to "use the full watts" from your amp, you'll be disappointed. More cone is the better way to get louder.

The first sentence in your post says you DO like the cab. Adding a second one (the SAME ONE) will give you more of the same things you like, and make you louder. As far as increasing the high end, have you tried NOT increasing the EQ frequencies on the lower end. In effect, boosting the highs by lowering the other frequencies and turning the volume up? Are your strings old? Why do you want to avoid a second cab? What is the amp?
 
#3
basscooker said:
You may be better off with a different cab. A budget cab is a budget cab. Nothing wrong with that, but if you aren't happy with what it is, changing it could really be good money wasted. You just aren't satisfied with what that cab has to offer. Why do you want it to be 4 ohms? If it's to "use the full watts" from your amp, you'll be disappointed. More cone is the better way to get louder.

The first sentence in your post says you DO like the cab. Adding a second one (the SAME ONE) will give you more of the same things you like, and make you louder. As far as increasing the high end, have you tried NOT increasing the EQ frequencies on the lower end. In effect, boosting the highs by lowering the other frequencies and turning the volume up? Are your strings old? Why do you want to avoid a second cab? What is the amp?
Click to expand...

I won't lie it is to get the full power out of my head. It's a tc rh750. And I really haven't boosted the low end at all really I keep it relatively flat. An I'm using it at home for the time being now and we don't have much space for a big amp (I sold my ampeg 6x10 for that reason) so I'm wanting to get the most out of what I have. I had the cabinet since they came out practically so it was the easy thing to convert into a compact powerhouse. I knew going into it the speaker would cut the power in half but I figured I'd worry about it later cause I got such a good deal on the speaker. I know upgrading the tweeter will help since it's the stock one that came in it that I may or may not have blown trying to be krist noveselik when I was 16 I haven't really thought about checking it until now. And the crossover would probably help too. As well as a new speak on jack. Im not so much looking for a different cabinet just a little extra frequency response and less ohms to get the full potential out of my amp.
 
#4
What sort of "highs" are you missing? If there's room, you might consider replacing the tweeter with a 6" speaker instead. That'll fill in that 2.5-5khz area that's really "treble" for a bass guitar.

If you stick with Eminence products, their 1.6khz "board only" crossover and LA6cbmr driver will make it about as easy as that mod is going to get.

One option anyway...
 
#5
I see. Well, definitely make sure the tweeter is working. As far as the other stuff, well, it is what it is. I don't think there's much that can really be done to improve the cab short of basically rebuilding it, in which case, you could find a better one cheaper. There really isn't much that going to 4 ohms will do for you except blow the speaker quicker. I have REALLY serious doubts that you can do the full power of that amp through any 15" driver that wouldn't cost you as much as a different cab.


EDIT:
Will is on to something there.... that stuff would keep the costs manageable. And unless I'm brainfarting here, show the amp 4 ohms.
 
#6
will33 said:
What sort of "highs" are you missing? If there's room, you might consider replacing the tweeter with a 6" speaker instead. That'll fill in that 2.5-5khz area that's really "treble" for a bass guitar.

If you stick with Eminence products, their 1.6khz "board only" crossover and LA6cbmr driver will make it about as easy as that mod is going to get.

One option anyway...
Click to expand...

If I wired a speaker in place of the tweeter how would I go about wiring it in to make it 4 ohm? If I did that would it blow it at higher volumes? How do watt distribution work on something like that? I'm not really wanting to push the volume on the amp I just want to know that if I wanted to get loud I had the headroom to do so. Like if I started playing out again and needed the volume my ampeg had I'd like to know I could get that kind of volume I needed. Granted I know at nicer bigger venues I don't need that much volume because they'd run direct out.
 
#7
You would need that crossover. Or A crossover. No special wiring involved, just matching the (+) to (+) and (-) to (-). Those prebuilt crossovers always have the right stuff labelled, and/or come with instructions. I'm still not 100% sure it would give you a 4 ohm cab.
 
#8
You simply cannot wire a single 8Ω driver to achieve 4Ω. You would have to replace the driver with a 4Ω version to do that. A mid-range or tweeter wired using a proper crossover doesn't change the total impedance of the cabinet. You seem to have been lucky in the change driver crapshoot in that you seem to like the result.

A mid-range driver will have to be isolated from the air space of the cabinet. Some are closed back which fulfils that function. Others will need an enclosure fabricated within the larger cabinet.
 
#9
basscooker said:
I see. Well, definitely make sure the tweeter is working. As far as the other stuff, well, it is what it is. I don't think there's much that can really be done to improve the cab short of basically rebuilding it, in which case, you could find a better one cheaper. There really isn't much that going to 4 ohms will do for you except blow the speaker quicker. I have REALLY serious doubts that you can do the full power of that amp through any 15" driver that wouldn't cost you as much as a different cab.


EDIT:
Will is on to something there.... that stuff would keep the costs manageable. And unless I'm brainfarting here, show the amp 4 ohms.
Click to expand...
The "board only" is a 2-way crossover. It'd stillbe an 8 ohm cab. Just one plays lows & mids, the other uppermids (where the "hole" is between woofers & tweeters), and highs up to 5k or so.
 
#10
So theoretically say I made another enclosure inside of the larger one and put another speaker inside how would the watts be distributed? I just feel silly now because after delving in deep the last little bit I figured out there's no way that I'd ever need the 800w speaker in this cabinet unless it was 4 ohm so as of right now it's kind of pointless. Is there a way I could wire a ghost speaker that would simply stand as a way to convert the power to 4 ohm?
 
#11
I don't think I'd spend a lot of time on the cab. It'd mostly be a crap shoot (unless you are an engineer skilled in cab. design). But if you have time and $ to (potentially) burn, have at it. Here's a silly suggestion......buy a new set of brighter (steel?) sounding strings???? At the very least, make sure your tweeter is working!!!!!!!!
 
#12
chaunceyjiggson said:
So theoretically say I made another enclosure inside of the larger one and put another speaker inside how would the watts be distributed? I just feel silly now because after delving in deep the last little bit I figured out there's no way that I'd ever need the 800w speaker in this cabinet unless it was 4 ohm so as of right now it's kind of pointless. Is there a way I could wire a ghost speaker that would simply stand as a way to convert the power to 4 ohm?
Click to expand...

You would need a crossover..... Just adding another speaker is a recipe for disaster. There's just no way for you to get this "magical 4 ohms" you seek without changing the driver. I was confusing you by accident about adding the mid driver. I thought the crossover network would apply the impedance like a parallel connection, but it won't.

As it is you have $2000 worth of wheels on a $200 car. You REALLY won't see much difference in output from the same cab going from 8 to 4 ohms. It would be like if you just added 2 or 3 more clicks to your volume knob, not 10 more. Maybe bassmanpaul can explain it better, cuz he's been in the thread already, but IIRC you need 10x power increase to get 2x volume increase. You aren't "wasting" the amp's power the way it is. If anything you have a speaker that you basically CAN'T blow up with your current setup. You're maybe a bit too hung up on "watts". That is a spec that while good to know, isn't nearly as important by itself as marketing departments would have you believe.
 
#13
Yep. The crossover handles the distribution. The 6" I mentioned is a closedback, it doesn't need a extra subchamber inside the cab, just cut the tweeter hole bigger and install it.

That'd be about $100 mod that's relatively easy to do and garner some noticable improvement. That's about as much as I'd care to spend to "fix" what you've got. More than that and I'd just say look for a different cab. Unless you want to use this one as a learning platform to keep toying with, for educational purposes.

Somewhere around here is a thread where guys did that to an Avatar 112 cab with good results. You'd be doing essentially the same thing to your 15. Search up "Avatar 112 midrange mod" or something like that.
 
#14
Here....

http://www.talkbass.com/threads/sin...ied-avatar-sb112-with-midrange-driver.926963/

You'd be doing essentially the same thing to your 15.

Not saying "you must do this" or anything, just saying it's an option that doesn't cost too much and will extend the range of your cab. Paper cones generally take to overdrive tone, etc. better than tweeters as well. You'll lose the really high "air" sound from your tweeter, but gain a good bit of output and dispersion where the bass actually still has a good deal of content in the tone.
 

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