Acme FAQ
Questions
Q. Should I choose an 8 ohm or a 4 ohm unit? Hello, Landon A. There are no "pros and cons." It's about matching the speaker to an amp. In your case, I would recommend the impedance which would allow the amp to deliver it's full 500 watts to the B-2. Check your manual. Most people choose an impedance of 4 ohms, because most amplifiers produce their maximum power into this impedance. Sometimes it is necessary to bridge a smallish stereo amp to get enough power for our low-efficiency cabs. In cases when an amp must be bridged, the 8 ohm cab is usually, but not always, the best choice. Q. About connecting speakers in parallel with one another I recently purchased a B1 cabinet and because of the great sound I then purchased 2 B-2 cabinets. I really love the way my basses sound through the Acme cabinets. I used to do some work at a friends studio and I loved the way my bass sounded through the monitors in the control room. I used to wonder why I couldn't get that full range sound in a live situation and now I can. I have a question about connecting my speakers to my amplifier. I have a SVT 4 Pro amplifier that I usually run in mono mode using a speakon connector to one cabinet and then I usually go out of that cabinet with a standard 1/4 inch connector into another cabinet. Can I connect my 2 Acme B-2 cabinets in the same way? Each cabinet is 8 ohms so I would like to go out of the SVT 4 Pro with a speakon connector into the speakon jack of the first B2 and then plug a 1/4 inch connector into the 1/4 inch jack of the first cabinet and plug the other end into the second B-2. Would there be any problem with doing this? Thanks for making these great cabinets. Marc A. This should work fine! Thanks for the nice note. Q. More information on "W" subwoofer systems When you say that these cabs should not be used "full range" do me mean that they will not sound good, or that they will be damaged by higher frequencies? I'm looking for a set of cabs that can deliver monstrous amounts of low end with no distortion and I keep hearing wonderful things about Acme. I'm thinking of trying out a B4 and a B4W together, would these need to be bi amped or could them be run in parallel? A. What I mean is that they shouldn't be expected to reproduce the full range, just bass. You won't damage them by running a full-range signal, you just won't hear much top end. Biamping would be a mistake. it would only allow 4 woofers to carry the bottom, instead of all 8. Run them both "full-range," so to speak. 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? Also is there a difference in tone between the B4 and B4W besides the absence of upper end on the woofer? In other words would a B4W give me stronger low end than a second B4? 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. No difference in tone - just no top end. Same bottom. Thank you for all your help, I'm really impressed by how forthcoming you are with info about your products. I'm still trying to decide if an Acme cab is right for me, there's one more thing I need to find out. Can the low B4 cabs go lower than B? I play in several different bands and tune down as far as G on occasion. Could a B4 handle this or would I be outside the range that it could deal with? A. Power handling decreases rapidly below "B." Not recommended. The notes will be reproduced, but at lower levels, and at greater risk to the cab. Q. Should I put casters on my 4x10 cab? I was wondering if the B-4 is available with casters A. We don't recommend casters because they decouple the speaker from the floor, which ain't good for bass reproduction. Andy, Quick question: I've been using a convertible dolly/cart for rolling these around, but it's really cumbersome when I play coffeehouses and small bars where I have to wade through a sea of people. My rehearsal space is up stairs and through tight spaces, so I find myself carrying the cabinet more often than putting it on the dolly... but having wheels would really solve my problems. I know you said you recommend against putting casters on the cabinets, placing the B-4 on the ground with an amp on top... but I've been laying my cabinet on it's side and stacking the other on top of it, with my rack atop the stack. My cabinets are in constant contact with the stage/floor at all times. Could I put casters on the bottom of the cabinet without doing any structural damage to it? My main concern is that, if I drill 16 holes (4 per wheel) into the bottom panel, the pre-tension will split the wood. From your perspective, would this happen? I'd really like a definitive answer on this, and I'd really like to have casters on my cabinets. Thanks so much for all your help, Andy. A. I think you'll be OK. It won't hurt the cab, I just don't like casters! Q. What about breaking in my new woofers? I played my Series I Low B2 with the new speakers I installed from you on a gig last night. Unfortunately the first thing I noticed is that is that the volume is lower and there isn't as much low end as on my Series II Low B2. I believe it could be because the Series I was tampered with by my 2 year old daugther shortly after I received the replacement 10" speaker from you. Long story. Richard A. The woofers in our Acme Low B Series II models have a break-in period. The surrounds on these woofers have a higher stiffness new-out-of-the-box than they do after some hours of use. This has two real-world consequences. The first is that the ability of the systems to reproduce the lowest notes doesn’t reach it’s full capability until the surrounds have been loosened up by being used. The second, and perhaps more important consequence, is that when driven to their maximum excursion, the woofers are much easier to damage when they are new, than after they’ve been broken in. It is more likely that the cones will be overstressed the when the speakers are brand new, than at any time after they’ve been used. How much break-in time is necessary? I have broken them in using a sine-wave generator in less than three hours. I believe that whan playing bass, it is very difficult to predict how long it would take for a specific person to do it. It depends on your style, and how loudly you play. My best advice is to start slowly, and work you way into it. Within reason, of course, the longer, and the more gradual the better. But please do your best to loosen up the woofers before you get into any serious slammin.’ The reason I have chosen to point out these concerns about breaking the speakers in, is because just lately, I have had two customers damage their woofers within the two-week trial period. This was unheard of just several years ago. The woofers are the same. But I believe that the availability of incredibly powerful amplifiers, even more than just a few years ago, has sort of changed the landscape. Q. Light bulb questions and whimsy Is it ok to use a bulb marked 24V 21W instead of your regular 12V 21W bulbs? David A. Nope. The 24v bulb would have too high a resistance, and wouldn't allow enough current. Having trouble finding an 1156? I can send you a bunch if you want. High school electronics: P = VI so doubling the voltage while holding the power constant means halving the current. Also V = IR so doubling the voltage while halving the current means quadrupling the resistance. No wonder it didn’t sound so good! David Customer writes again: At Bulbs Direct (no joke!) they show: Volts: 12.8, Watts: 2.1, Base: BA15s Is there likely to be any practical difference? In Talkbass there was some discussion about a “ruggedised” bulb used by Harley – any thoughts? David A. I think they're all more or less equivalent. I like the green Sylvania packages, though. I've heard of the Harley bulb, but I would hope vibration of the crossover should be low enough so it wouldn't make any difference. At any rate, I don't know if there's any difference, but I doubt if HD is in the bulb business. I've been using Eikos lately, and they seem fine. Actually the 1156 is generally rated at 50 watts, not 2.1. In my tests, the bulb fails at about 23 volts and its resistance at that point is about 6-6.5 ohms. At this current, as you can calculate, the bulb is actually dissipating around 80 watts! Thanks, A Customer writes: Andy, I think I’ll start a thread on Talkbass extolling the sonic differences of various light bulbs in Acme speakers – should get the interest of the guys with the $1000 power cables. David Q. Will my distortion pedal cause the fuse-bulb to melt? Hello, sorry to ask a stupid question, but here it is - I have been reading on the harmony central website that one person was blowing the fuse using a distortion pedal and was just figuring that he was overdriving the amp or something. Would you not recommend using a distortion pedal or fuzz with these speakers (and a good amp), or was he either unlucky or just misusing them? A. In general, using these devices would probably increase the chances of frying the bulb, but I haven't heard a lot of complaints about it. If it's happening, people are telling Harmony Central, but not me! Q. Let's talk about the Carvin 1000 amps I have a Carvin Red Line 1000 watt bi-amp. I was thinking that the best combination for portability and volume, would be two of your cabinets, a B-2, and a B-2W, both 8 ohm.,with the amp bridged in mono, which would give me a 4 ohm load at 1000 watts of power. Does this sound like the way to go? A. Yes. This is a popular combination, two 8 ohmers w/the Carvin. That amp is a little touchy at low impedances, based on my customers' experience, but after the speakers are broken in, in a few hours it seems to handle the load quite nicely. I recommend that amp when asked, because it has more power per dollar than any other amp I know of. Customer writes: Andy,what do you mean the amp is touchy at low impedances? What is the down side? What would you recommend as a speaker configuration using the Carvin R1000? The amp will shut down if the impedance drops even very slightly below 4 ohms. Most amps are a little more tolerant in that regard. But the Carvin's a good deal. Just as you proposed: a pair of 8 ohm cabs in parallel, driven by the Carvin bridged is the best way to go. A. A
little bit of information about the level controls on power amps: I’ve
had unfortunate conversations with an alarming number of people who have made the same
mistake: A
great many people, I’ve learned, believe that a 1000 watt amplifier becomes a 500
watt amplifer once the level controls are set to “halfway up,” “12 o’clock,”
or “only at 5,” if you catch my meaning. I
would prefer not to have this conversation any more, because it usually is with some
well-intentioned kid whose woofers are in tatters, and who can’t understand what he
did wrong. So, read this twice if you have to: Lowering the setting of the Level, or Volume control on your power amplifier does not limit it’s ability to produce it’s full power! If a 1000 watt amplifier is only turned halfway up, it does not become a 500 watt amplifer! It is still able to produce it’s full 1000 watts if it gets a “hot” enough input signal. |
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