Going to add a cabinet

[drbassman]

I will give full report on the cheesy cab when I use it at practice.  We're off for two weeks, but I'll give it a thorough test when we get back at it.  In fact, I think I'll bring the Mesa amp home today and test it out here.  That could be fun!  I'll be back.......

[Granny Gremlin]

 I'm getting the 15" flipper from Ampeg.  Found it on sale for $330.  If it farts on me, I'll upgrade the speaker myself.

Though I agree with Mark's assessment earlier, I think this is a good plan (especially if that cab won't be driven as hard as the spec says it can - being a secondary extension cab).  Drivers are easy to upgrade and you can easily get $50-100 for the old one.

just out of curiosty,what cab are you playing through granny g?

The Musicman RH115 I mentioned before is my main gigging rig (slightly modified in that I extended the internal reflex horn and swapped the driver out for an EV SP15c, which is the fastest transient responding and brightest 15 I have ever heard, but still has plenty of bottom - the amp is only a 100 watts vs the speaker's handling of 300 so farting out isn't an issue despite the light cone).  Alt cabs include the DIY sealed 8x10 with vintage Rola alnico drivers and 2 1x12 transmission lines with a selection of drivers I swap out for various uses (bass, guitar or small PA for solo acoustic gigs).

They can all be seen in here (Musicman on the right, grey grille, one of the 1x12s and the 8x10 on the left):


wait this one's better (don't let the Traynor badge fool you, that's how I found the MM in the pawn shop; didn't know what it was at the time, but the price was very good, and I'm so very glad I bought it... originally it had a crappy Eminence stamped frame, bottom of the line driver in it), I think that's a JBL E120 in the 1x12:


Dave, I really don't understand your problem or your attitude here and am just gonna leave this alone with you.  I was trying to be helpful and I think it was somewhat appreciated so I'm just gonna hit it and quit.  Keep rolling your eyes if you must but it's just making you look like a grump.  I don't know why you are making it personal like this; we're talking about speakers not politics or religion.

[drbassman]

Hey, all's well with me.  Don't asnyone go away yet!  I gotta another dumb cab question.  I have the Mesa 1x12 and 1x15 cabs wired direect/parallel out of the Mesa amp, each 8 ohms.  Can I take the parallel out jack on the Mesa 1x15 and just run it into the new Ampeg 1x15?  How does that affect the amp output?  Man, I just have never learned this stuff!

[Granny Gremlin]

That would be 3 cabs in parallel, and assuming the Ampex is 8 too that would total 2.66666 (repeating) or if 4 just 2.  It's possible you amp will be OK with this, but check.

[drbassman]

I found my paper on calculating ohms.  If I figure it correctly, hooking up 3-8 ohm speakers to the amp would yield the following:

(8x8x8)/(8+8+8) = 21.33

Is this correct?  My amp is 300 watts at 4 ohm.    300x (4/21.33) = roughly 60 watts.  Mathematically, it makes sense to me, just wanted to be sure I didn't miss something.

Sounds like a need some 4 ohm drivers in the mix.  (I do have a new 4 ohm 12" in the closet)

[drbassman]

That would be 3 cabs in parallel, and assuming the Ampex is 8 too that would total 2.66666 (repeating) or if 4 just 2.  It's possible you amp will be OK with this, but check.

Opps, my calulations are off then.  The amp is rated 300 watts at 4 ohms.  Did I miscalculate or is formula incorrect?

My original thought was to just use the two 15", 8 ohm cabs and leave the 12" cab out.  I might stick with that thought and get rid of the weak link anyway.  As I said, the club is small, I want more bass, volume optional!   

[Granny Gremlin]

We were posting at the same time so I guess you didn't see mine, but you're off.  Parrallel speakers' total Z is always less than each cab on it's own (as a math check); series is easier and just adds up.

series: Ztotal = Z1 + Z2....

parallel: 1/Ztotal = 1/Z1 + 1/Z2 +..

so in your case:
1/Z = 1/8 + 1/8 + 1/8
1/Z = 3/8
1/Z = 0.375
Z    = 2.6666666666666666666666666666666666666666666666666666666666666666

[drbassman]

We were posting at the same time so I guess you didn't see mine, but you're off.  Parrallel speakers total Z is always less than each cab on it's own (as a math check) - series adds up.

I see, wrong formula on my part!  Thanks!  Three 8 ohm speakers is not the way for me to go.  I don't want to take the Z below 4 ohm rating.  Thanks!!!

[Granny Gremlin]

the formula was expanded/simplified incorrectly from the root formukla I posted above.

A quick cheat (that ONLY WORKS IF ALL PARALLEL CABS ARE THE SAME Z) is:

 Z of each cab/# of cabs

so therefore:

8/3 = 2.6666666666666666666666666666666666666666666666666666666

If you're mixing 8s and 4s (etc) you gotta use the original formula I posted.

[drbassman]

the formula was expanded/simplified incorrectly (I double checked and got the same answer).

A quick cheat (that ONLY WORKS IF ALL PARALLEL CABS ARE THE SAME Z) is:

 Z of each cab/# of cabs

so therefore:

8/3 = 2.6666666666666666666666666666666666666666666666666666666

Thanks.  Gotta figure it out with the 12" 4 ohm cab in the mix.

[drbassman]

Math check, please!

1/Z = 1/4 + 1/8 + 1/8
1/Z = 4/8
1/Z = 0.5
Z    = 2

[Granny Gremlin]

yep

[drbassman]

yep

Looks like I'm going with the two 15" cabs.  Thanks so much for your help!   

[Granny Gremlin]

no sweat, dude.

[jumbodbassman]

I will give full report on the cheesy cab when I use it at practice.  We're off for two weeks, but I'll give it a thorough test when we get back at it.  In fact, I think I'll bring the Mesa amp home today and test it out here.  That could be fun!  I'll be back.......

The fliptop ampeg cabs have a horn BTW.  And it is a sealed cab so sometimes the tops will vibrate if not really tight.  It will not sound as deep as a ported cab.  Supposedly the eminence speaker in the fliptop is pretty good.  Ampeg just introduced a 15 cab with ports and is not a fliptop but same look.  Not sue if they are out there yet.