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Acme to Accugroove

#21
BassmanPaul said:
I use a Carvin DCM1000 with my pair od Acme B2s. One cabinet per channel run in mono. Works beautifully. Bridging a '1500 would supply way too much power for a pair of B2s. Running a '1500 like I run my '1000 would supply a perfect amount of power for four B2s around 375W per cabinet. The dolly option (slab of 3/4" plywood with four good sized casters) means one trip. Unless there are stairs then it's the Rock 'N' Roller cart! ;)
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One man's 'way too much power' is another man's comfortable headroom.

I'd rather keep the amp loafing along in it's optimal parameter zone than working hard, pushing its limits.

To me having more power than you need results in better dynamic response from the speakers and more oomph in the low end.
The possible downside is creasing cones or blowing drivers if the player is not careful.
 
#22
BassmanPaul said:
Bridging a '1500 would supply way too much power for a pair of B2s.
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Nope, not too much at all. I've never had a problem with 1000W per Low-B2, 2000W into the pair, even when hitting the limiters occasionally.

As greenboy says, each woofer needs in the order of 250W in the lowest frequencies to reach full excursion assuming no power compression. Figure in power compression and the distribution of power across the whole frequency spectrum and you see how these cabs can handle a tremendous amount of power without damage. If you can hear yourself then over-excursion distortion is pretty obvious at which point you can turn down long before damage is likely.

Alex
 
#23
They're 8 ohm cabs, so I'm running bridged with the cabs in parallel, or just one at a time if I don't feel like hauling them both in. That puts me at ~500W per cab. I have yet to light up the red "clip" LED on the amp. Kind of afraid to test that boundary, just because I want to protect the drivers. I do run with the -20dB lit up most of the time.

I went to the church today, and the only marginally accessible amp is a PLX3002, so maybe I'll try that tomorrow when I've got a little more time. Should I still run it bridged like my Stewart is, just don't crank the volume up too high? What happens if I give my Acmes too much juice? Will it overheat the voice coils or damage the cones/spider/surround?

Honestly, even with a cart, I think I would still like the one-cab solution. I measured my car and a Whappo Jr would fit in the back seat, and only weighs 10 lbs more than one of the Acmes. Also, I'm not so sure I need the extended low end, as my church has a great house system with four subs but my drummer still complains he can't hear me unless he uses the Avioms (which don't go with us when we do other gigs). Although maybe I'll change my mind when I try the Acmes with 3 times the power.

My end goal is to have a smaller rig that's at least as loud, while still being accurate. Right now, my preamp is a Sansamp RBI. Unfortunately, it doesn't play real well with our electrical system (that's a whole other issue), and I find I don't use it much anyway. Mostly what I do is use my TC Electronic M-One with a little compression, EQ, or delay (when we cover U2's "40").
 
#25
Owning four Acme cabs and now purchasing a 5th...

I'll chime in with everyone else. Get more power into those Acme Low B2s! That Stewart 1.2, even bridged into the parallel 4 ohm load is simply not enough.

You'll have a whole other set of speakers you haven't heard yet if you can at least double that power to 2000 watts, and with something other than a switching amp like a Stewart.

I know this doesn't answer your original question... but nonetheless :)
 
#26
bassbrock said:
{...} and with something other than a switching amp like a Stewart.
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I wouldn't lump all the Stewart World series together (or SMPS-equipped amps for that matter): the World 1.2 is an earlier Stewart design and has a history of not being able to meet its stated output especially with more difficult loads for any meaningful duration. From my limited time around other Stewart Worlds they don't seem to exhibit the same tendencies.
 
#27
Thanks for clarifying that greenboy, my intention was not to lump them all together like I did.

Anywhoo...

Even Andy 'condones' more power:

Any recommendations in regards to power? I am looking at a QSC PLX2402, which would give me 2400 watts into 4 ohms when run bridged. Would that be adequate or would I need more?

A. I like to see 800-1000 watts per 4x10 cab, be it a regular cab or a "W" cab. Your 2400 watts would be enough that you would have to be careful to avoid damage, but it would be a great sound.
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From his FAQ page.

Granted, that is referencing a Low B4, but the same concept would apply to two B2s. 2400 Watts is enough to cause concern (you could potentially cause damage) but if you are careful it is very unlikely.
 
#28
I bought a wheeled cart at Home Depot to haul my Acme Low B2s around with. It's a LOT cheaper than buying an Accugroove!

Also, I have had the best results with my two Acme Low B2s (mine are 4 ohm) with a QSC PLX 3602, which is 1200 watts per channel into 4 ohms. I would run each cab off of it's own channel in parallel mode. The QSC RMX series is less expensive than the PLX because it's made in China. It's quite a bit heavier, but Andy Lewis recommends putting a lot of weight on top of his Acme cabs anyway.
 
#31
Hi all,

Just a quick +1 on lots of lead-sled power for Acme's. I just played a very large end-of-summer company picnic in the Seattle area with my two 8 ohm Low B2's powered by a new-to-me Crest CA9 and Demeter VTBP 201S.

The sound ... WOW! Without any tweaking, it was by far the best tone I've ever gotten live. Of course, there were many variables that could have contributed to the quality of the sound (i.e. open stage, good power, excellent drummer, etc.). Still, this is the biggest, boldest, cleanest punchiest bass sound I've ever heard. Lots of compliments from the sound guy and some audience members too.

Good luck,
Greg Backstrom

Johno Dunn said:
Not to drail the thread, but I used to run 2 4ohm B2's w/a Fafner, and it was GAWD like tone. Do you Acme owners think a Little Mark II would be enough to power 2 8ohm B1's, or would I be better off w/1 4ohm B2 (and would the 500w's be enough)?


Johno!
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#33
JonathanD said:
You really put 900 watts into each cab? Are you not pulling back on the amp at all?
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According to WinISD Pro or Eminence Designer the Acme drivers should be able to handle 250 watts apiece without exceeding xmax. So 500 watts per driver would be 3 dB headroom above useful excursion. Provided the crossover and other components are up to it, the woofers certainly should be.
 
#34
greenboy said:
Hate to be brutal but every Stewart 1.2 I've ever had to use ran out of gas when asked to actually deliver its rated output for any period. Some other amplifier needs to be in your system driving an Acme to really know what's the deal. I'd recommend 350-500 watts per woofer.
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+1
The 4 ohm B2's here have about 700~750 RMS simply for that reason & headroom. Andy did say be careful so a 30Hz filter AND a dbx 166 is used. A handtruck helps along with a baby suv(Chevy Tracker) as a gigmobile.
 
#35
I agree with everyone above that says you will find what you are looking for with a more powerful amp and a hand cart. The only time I ever venture away from my Acme's is if I must use a low powered tube amp in a high volume setting. In those cases, I need a much higher efficiency cabinet. Other than that, one or two B2s are unbeatable in every respect.
 
#36
gregbackstrom said:
Hi all,

Just a quick +1 on lots of lead-sled power for Acme's. I just played a very large end-of-summer company picnic in the Seattle area with my two 8 ohm Low B2's powered by a new-to-me Crest CA9 and Demeter VTBP 201S.
Click to expand...

Were you powering those Acmes with the CA9 run in stereo mode (600 watts each), or bridged mono (1,000 watts each)? Just curious...

MM
 
#37
Just a point if part of the idea was to get an overall lighter and more easily transportable rig then going for heavier power amps is not necessarily going to solve the problem.

I think a Focus was mentioned with the Jr I would have thougth this would have worked well, and only weighs 5lbs [approx] which meets another part of the criteria. So I say go and try out the JR and the Focus, I think you will be suprised.

Regards

Matthew
 

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