upgrade? major benefit or not-so-much?

[hobbes1]

I've been reading a variety of threads here. Here's my situation:
I have recently picked up a used GK MB200 and running into an Avatar SB112 8ohm neo cab + a home brewed 1x12 ported cab with an Emi Delta Pro12a (8ohm) speaker (I lined the cab with batting which has helped control the low end). This small rig sounds good and I checked with GK (Brian) who told me it's ok to run the MB200 wide open as long as I needed and it should be fine to handle that. The only issue I have is the very lowest notes just slightly seem to overdrive the speakers so I'm working on tweaking my EQ to control the 5th string output (turned bass on MB200 all the down and rolling back bass on my Tobias Growler (gibson era), slight low mid bump and slight hi mid bump and treble mostly down).

So, my question is, I want to continue this cab rig and trying to decide if I should upgrade to a more powerful amp. I'm looking at ampeg pf500 vs. GK MB500 vs. Carvin BX500. I have read of people with problems with the PF500 and BX500 cutting out and dying. So, that issue aside, I'm wondering about the volume benefits of the larger amp.

I will be playing with a three piece (guitarist with DT25 combo/POD HD500 and acoustic drummer who is very good at controlling dynamics) band, mostly playing private parties. Could be indoors or outside on patios. We are all over 40yo, have played together for years, no issues with super loud guitarist, etc or stepping on each others toes volume wise
The music would be classic rock, blues and some jazz stuff.
I have clocked the current rig output at about 103dB at 6 feet away if that helps reference the volume I can get with the MB200 wide open.

opinions? please don't anyone suggest I need a fEarful or Thunderchild, etc. I want to maintain my budget of getting a used head <$300. I like the two 1x12 approach and like the sounds of these cabs. I want a lightweight, smallish amp but just wonder if it's really worth it to upgrade the amp to a more powerful 4 ohm output. Thanks for any opinions, pro or con.

[CL400Peavey]

Quite honestly its not going to be an upgrade. You will probably be limited mechanically before you see a real gain in volume from power. Two 112's will only be so loud regardless of how much power you have. If you want significant volume gains, you need more or more capable speakers, which will increase your power handling as well.

[xring]

I'm confused. You say you are running 2 - 8 ohm cabs which is a total 4 ohm load, yet you say you want to upgrade to a more powerful 4 ohm output? Also, if the GK is wide open on the master, I can't see that sounding very good thru most any cab. It's got to be clipping. I do know that the MB500 will be plenty for those cabs. I occasionally push a Fender Pro 610 with mine and it goes very loud and clean (if that's what I'm going for), and with the gain at 1 oclock, the boost master at 8 oclock.
I think with your MB200 maxed, the low notes are calling for more power (no headroom at all left), and that's why she's breaking up. Upgrading to another amp seems to be the best option, and appears mandatory in your case.

[craig.p]

You may be getting phase cancellations up and down the spectrum with that pair of non-identical cabs. That would cause you to burn more watts than necessary to achieve any given sound level. I'd address that problem first.

[BassmanPaul]

Do the battery test on the two cabinets to make sure they are both working with the same polarity.

[derrico1]

Originally Posted by hobbes1

the very lowest notes just slightly seem to overdrive the speakers so I'm working on tweaking my EQ to control the 5th string output

First step is to verify whether you're overdriving your speakers or your amp to get to the volume you want. If you're right that the speakers are giving you all they've got, putting a more powerful head in front of them won't make them give you any more. OTOH, if your amp is clipping, you *might* get more out of the cabs with a more powerful head driving 'em.

The GK MB200 has a direct out. If you're able, record the DI while you're playing at the levels and the settings that are clipping your B string.

Does the clipping you hear through the cabs show up on the recording? If so, you're pushing the amp itself into distortion to get volume. If the amp is the bottleneck, you might be able to change your gain structure and eq to squeeze more out of the GK, or you could switch to a bigger head. (Keep in mind that you could put a 500 watt head on top of these cabs, only to find that the cabs are close to clipping just as the GK is giving you all the headroom it had on the B string. If that's the case, a new head won't necessarily give you much more appreciable unclipped volume or headroom. For that reason, I'd suggest borrowing a bigger head to test before buying.)

If, OTOH, you find that the DI signal records cleanly even when you hear the cabs starting to distort on the low notes, then you know that you're reaching the limits of your cabs. Since you're running two different cabs, I'd also suggest then running the rig w/ both cabs hooked up to longer speaker cables so that you can separate them enough to tell whether only one of them is distorting under the load. If so, you might think of swapping out *that* 1x12 to test a more robust 1x12 in its place. (Ideally, you'd end up w/ two cabs of the same design.)

[hobbes1]

lots of good advice here. thanks.
@xring: yes, the idea was what if any benefit a more powerful (eg: 500watts) 4 ohm amp would be. the delta pro 12a is a 400 watt speaker but the deltalite 2512 in the avatar is a 250 watt speaker.

@derrico1: good ideas. if i play the 5th string slightly gentler the little bit of distortion goes away and the speaker(s) handle it fine. either cab alone (8 ohm load) gets 140 watts and that doesn't seem to be enough to distort. **edit: I need to go back and confirm this as I cant remember if I had the head wide open or not when I demo'd the cabs seperately**

the MB200 sounds good wide open. it does not sound anything other than clean on any notes except that slight, momentary distortion on the lowest notes below low E. even then, it's only distorting on the first part of the attack of the note, if i hit the string a little aggressively. (i've been playing this bass for 15 years so i know how to use it dynamically and i don't really play heavy handledly).

i have a used boss bass eq pedal coming to see if i cut the 50 Hz down/off from the bass, if that will solve the distortion issue. but as far as two diff cabs phase cancelling, that's good info and something to sort out.

[hobbes1]

Originally Posted by BassmanPaul

Do the battery test on the two cabinets to make sure they are both working with the same polarity.

thanks to you and craig.p

is there a specific name for this test and directions? i seem to recall hearing something about the battery making the driver move in and out a certain way? rings a distant bell in my head...**found some references here about it. thanks!**

[bumperbass]

Put the plus + on a 9V battery to the plus + input on each cab, (or both cabs) and the - to the negative (duh). Make sure the cones move in the same direction. They should move OUT if + is really '+'. If they do, you're good to go. I always make sure mine are wired with the plus + meaning it IS really the positive. Doesn't really matter if they both move IN instead of OUT, but might come it back to haunt you if you ever use either one of the speakers with another in the future.

I guess the technical term is 'polarity testing'.

[hobbes1]

Thanks Bumperbass

[walkerci]

Definitely try cutting the 50Hz a little until the problem goes away.