Mesa Boogie Powerhouse horn attenuation?

ubercore · #1 01-11-2011, 11:40 AM

I have an Acme B2 now, which I love dearly. Recently I've been using the bass amp at our practice space (A hartke 3500 into an Ampeg B2 combo with a broken amp, single 15" with the tweeter bypassed), and I've been even happier with it than the Acme. The acme, for the style of music I'm playing now, isn't quite cutting it with my T-40.

I think I'd like to move to something a little more low-middy, like a 12" or 15". Extreme low end is not my goal, I'm fine loosing some of the lowest-end frequency respond. I also tend to run my RBI pretty hot, so I will have some overdrive in the signal, so a defeat-able or attenuable (I made that one up!) tweeter would help some of the harshness I sometimes get out of the Acme.

I've played the Mesa Boogie 2x12 in the store, with my T-40 and their M6 carbine head. I really enjoy the sound; it's more in-line with what I'm hearing from the Ampeg 15", but retains some versatility that a tweeter-less 15" might lack. The question I have is with the tweeter. Looking at their website, it looks like you only get 2dB of attenuation (plus xover control). Is that truly the case?

Thanks!

BassmanPaul · #2 01-11-2011, 11:55 AM

An Acme B2 harsh - you have to be kidding!

That said, Acmes are not for everyone. If you are liking the sound from a tweeter-less 15 then look to that route.

ubercore · #3 01-11-2011, 12:08 PM

I'm totally willing to be wrong, but I keep getting these ear-piercing honks from my acme with my RBI! I thought it was underpowered maybe, gave it more power and the same happened. Asked about maybe a blown tweeter or mid, but was assured that was nigh-impossible from Mr. Lewis! I have the mid and tweeter fully attenuated, but I'm still getting the same thing. The strange thing, to me, is that the tweeter protection bulb never goes off.

I'm going T-40 -> Sansamp RBI -> QSC PLX 1402 (tried bridged and un-bridged) -> B2.

To be fair to the Acme, I really prefer a grindy Tim Commerford/Geddy Lee/Doug Pinnick style sound.

Any other suggestions to try taming my rig? I'd love to stick with Acmes (adding another B2 to help with volume, probably), but I'm just not sure the sound I'm going for is really in their sweet-spot. Very, very happy to be wrong though!

rockstarbassist · #4 01-11-2011, 12:14 PM

I play 2 of those cabs, and the tweeter is as loud as you could want it. And then if you want it shut off, you get that too (misread your OP). I have my cabs stacked and the tweeter just barely on w/ the top cab and it's plenty.

It's about a polar opposite of the Acmes, which for a lot of people (like me) is a good thing.
A perfect rock cabinet that can do other stuff as well, but going along with your tone description, it would just nail it.

I just moved an NV610 after serious use of about a year with it and for that grindy attack, these beat it in spades IMO.

KJung · #5 01-11-2011, 12:15 PM

+1 in that the Acme's are very smooth and 'polite' up top, and probably have the lowest ratio of upper mids and above versus deep bass than an cabs I've played.

There are attenuators on the back of the Acme cabs for the mid driver and tweeter. Play with those to determine what is causing the tone you don't like.

Most cabs have tweeter attenuation circuits, including the Mesa's, that can pretty much turn the tweeter off. However, if you use lots of distortion and grind, a one way cab with a mid oriented driver is probably the way to go (i.e., the classic sealed multi 10 sort of thing... like the Bergantino NV610).

Some guys have had luck with mid driver loaded cabs, like the LDS 15/6 or the fEarful DIY boxes. The mid drivers used in those cabs are MUCH more powerful than the Acme mids (high power 6" versions versus the small 5" used in the Acme), and they sound great... tighter down low than the Acme, higher sensitivity, and a very warm upper mid response that works will with the grind.

ubercore · #6 01-11-2011, 12:23 PM

The more I hear people talk about this, the more I wonder if there's more to this story. I have (to the best of my recollection, will do lots of testing tonight) the tweeter fully attenuated, and mid mostly off. Still with the honk.

I'm new to the pre/power amp world; is it possible for the RBI to provide a hot enough signal to clip on the input side of my QSC?

And thanks for all the feedback so far!

rockstarbassist · #7 01-11-2011, 12:29 PM

Hrm, dunno b/c I don't have much time on that cab. Could it be you're boosting a certain frequency? Try setting it flat w/ the horns + mid off and see if that helps.

And there's a lot of stuff about the pre+power levels and how they match and I don't think the RBI can do that unless you're clipping the front of the RBI itself.

ubercore · #8 01-11-2011, 12:49 PM

On the no-tweeter front, I'm really anxious to hear some demos of the Acme "flatwound" speaker.

BassmanPaul · #9 01-11-2011, 02:18 PM

I too think that you are miss identifying what you are hearing. If the L-pads are turned all the way down the mid and high speakers are basically out of the circuit. I suspect that you are hearing clipping from your RBI. I've had that when I was using one of my pre/power rigs and turned the pre up too far with the power amps levels turned down. It's a horrible sound.

ubercore · #10 01-11-2011, 03:14 PM

Thanks, you're probably right about misdiagnosing. It's hard to narrow down, so I was assuming it was tweeter-related.

I'm still having trouble hearing a difference in sound with the tweeter off, I guess I should have my ears checked...

Will report back after investigating tonight.

BassmanPaul · #11 01-11-2011, 04:05 PM

Not really, there's not too much information from a bass in the tweeter region. I find it just adds a little "air".

ubercore · #12 01-14-2011, 07:43 AM

Wanted to follow up in this thread as well as my older thread (Need help with my rig. Unhappy with sound). Tweaked my preamp (RBI) settings gigging last night. Backed off the blend knob, and it was a whole new experience. I could hear myself with nearly half the volume. Kept the tweeter down, but left the mid driver wide open, and it cut like crazy. No weird honks or harsh noises, so it was definitely the power amp.

I guess that's the blessing and the curse of Acme cabs; they just take whatever power you want to give them without complaining

I just needed to be careful to not spend all my amp's wattage in the lower frequencies that weren't cutting well.

So I think I'll hold off on the Powerhouse for now, although I still really loved the way they sound...