Which head for Acme Low B2?

Discussion in 'Amps, Mics & Pickups [DB]' started by thejumpcat, Feb 9, 2008.


  1. thejumpcat

    thejumpcat thejumpcat

    Sep 30, 2007
    metro-Detroit
    I finally decided to sell my AIContra combo with Contra extension cab because it just wasn't loud enough for a lot of our gigs (four-piece jump blues band).

    I grabbed a used Acme Low B2, and now I need a high-powered head to drive it. I'm looking at the AIFocus III; an EA iAmp800; or a LittleMark II.

    I use a 1949 Swingmaster with Realist p/u, and a P on a couple of tunes.

    Any thoughts on these heads, or something else with this cabinet?

    Thanks!
     
  2. barrybass33

    barrybass33 Supporting Member

    Jan 7, 2008
    westchester new york.
    i was in a similar sitaution with a older clarus and opted for a new a/i foucus much more headroom that i needed despertley and i use different cabs 1/12 2/10 i'm gigging a lot now 8 /12 times a month i got friend bought the little mark with epi cabs and i sat in with them i swap heads a i knew i made the right choice but i spent twice the money good luck
     
  3. Although the Acme cabs are very good in their own way, you are right that you're going to need a lot of power to drive the very inefficient Low B2. Hopefully you have a 4 ohm version, which makes this cab a little more practical. I'd say the Focus III is probably the best choice here. It has a lot of clean, usable power, and you're going to need the the Focus' high pass filter with this cab. I have a Little Mark II, and although it's a good amp, the Focus and the iAmp 800 both have significantly more power.
     
  4. Touch

    Touch

    Aug 7, 2002
    Boulder, CO
    I use an EA iAmp 500 with my 4 ohm Acme B2 Low. I can get it moderately loud. Due to the inefficiency of the Acme cabinet I can't get "stupid loud" with the iAmp 500. I am now using a Full Circle pickup into the iAmp.

    For my "stupid loud" shows I use an LDS 2X12 (w/ tweeter) which has a higher sensitivity than the Acme box. I really like the LDS however it is quite a bit larger. For a small box the Acme is hard to beat.

    I would think an iAmp 800 would be a good match if you're trying to get the Acme REALLY loud. A high pass filter like F-deck's or the lowest band parametric on the iAmps can also help tame the really, really low notes that one can get out of the Acme.
     
  5. thejumpcat

    thejumpcat thejumpcat

    Sep 30, 2007
    metro-Detroit
    Thanks for the info! I'm leaning to the Focus. I just got the Acme in the mail today, and I'm borrowing a friend's LittleMark II for Thursday's gig. I went to Low Down Sound last week and played about seven different cabs using an AIClarus. The best sounding, at least with my Swingmaster/Realist setup, was a 2x8. It was ridiculously tight and quick responding, and light! Don is building some really, really great cabs. I'll probably end up with his 2x8, too. His prices and quality are too hard to beat. I just got a good deal on the Acme, and had to pull the trigger just to see how it sounds. We'll see...again, the Focus is in the lead.
     
  6. bolo

    bolo

    May 29, 2005
    Apex, NC
    Same here. It was a Series I pair. No high pass filter, which I think in hindsight would have made a nice difference. fdeck's HPF-Pre wasn't around then.

    I used an iAMP-200 Wizzy combo for 3 years and was quite happy. Now I am using a Focus 2R SIII w/ an M-line cab, and it's even nicer. The AI heads are great for DB, IMO. Feature rich, remarkably small and light, great sound.

    The Focus sounds great too IMO with a Lakland Bob Glaub and a Joe Osborn. But I can see how it might not be beefy enough or live enough sounding for some players. I actually use a SansAmp BDDI with it for slab.
     
  7. Jeremy Allen

    Jeremy Allen Supporting Member

    Mar 18, 2002
    Bloomington, IN
    I used an iAMP 800 into an Acme Low B2 (4ohm) and it was about the sweetest combination I've ever played through; I got a really gorgeous sound with string bass, and with bass guitar it was stupidly loud and fat. I traded the iAMP for a Focus Series II (because of the schlep), and that also worked just fine power-wise. As long as you have at least 500 watts going into the Acme, IME, you'll be fine. (400 didn't cut it, and 120 from a Walter Woods lo-power into that cabinet was tragically funny the one time I tried it on a gig.)
     
  8. thejumpcat

    thejumpcat thejumpcat

    Sep 30, 2007
    metro-Detroit
    Did you miss the iAmp's tone controls, which appear to be a bit more advanced? What type of p/u on your upright? Guts or steel? Any feedback problems with either head through the Acme? Thanks!!
     
  9. Jeremy Allen

    Jeremy Allen Supporting Member

    Mar 18, 2002
    Bloomington, IN
    No. Amplifying string bass well, for me, does not involve much in the way of EQ'ing (except for the use of the all-important hi-pass filter). I just try to find something flat and let my fingers do the rest. I never touched the parametric EQ on the iAMP (and I've yet to meet anyone who has); the presets it comes with got me through about every situation, and there was even one that worked well for upright (in spite of what I said above).

    Revolution Solo I, Realist, even an Underwood once or twice.

    Both, as well as Velvets.

    Nope. The focus has the hipass and notch filter: the former is great for all upright amplifying, the latter is vital when using a mic on the upright. But I didn't have problems with the iAMP.

    What it comes down to is how much upright vs. BG playing you're doing. Conventional wisdom says if it's more BG, go with the iAMP, if it's more upright, go with the Focus (and get a SansAmp BDDI for when you have to play BG--this is pretty essential with the Focus!).
     
  10. drurb

    drurb Oracle, Ancient Order of Rass Hattur; Mem. #1, EPC

    Apr 17, 2004
    The difference between 500 and 400 watts is 0.97 dB, 1 dB for friends. If you found 500 watts okay and 400 lacking, it likely had less to do with the difference in wattage, per se, than other aspects of the amplifier design (e.g., headroom, current capability).
     
  11. drurb

    drurb Oracle, Ancient Order of Rass Hattur; Mem. #1, EPC

    Apr 17, 2004
    Well, we gotta meet sometime. :) I use the parametric section of my iamp all the time. I find it to be an enormously useful and flexible tool. I admit, however, that many feel that it's just too many knobs and dials. They do take some time to learn to use but, IMO, the time is well spent. In my case, as a result of years of professional exposure, I can pretty much walk into a room, play my bass and identify the frequency bands that need cutting or boosting. With not too much training, many can become fairly good at this. It's a useful ability to have in your bag of tricks.
     
  12. thejumpcat

    thejumpcat thejumpcat

    Sep 30, 2007
    metro-Detroit
    I must plead ignorant: What do the hipass and notch filters do? I don't believe the AIContra I just sold had either.

    I really only play EB on two or three tunes a night; some gigs I never touch it but just bring as a backup.

    The Acme cab is a 4 ohm.
     
  13. drurb

    drurb Oracle, Ancient Order of Rass Hattur; Mem. #1, EPC

    Apr 17, 2004
    A high-pass filter is a filter that passes frequencies above a certain "cutoff" frequency. For example, a high-pass filter with a cutoff of 40 Hz will allow frequencies above 40 Hz to pass through unattenuated while progressively attenuating frequencies below 40 Hz. High pass filters of this sort are particularly useful for preventing infrasonic (no, not "subsonic") frequencies from being transmitted from a piezo pickup to the amplifier (where they waste power) and to the speaker cone, where they can wreak all kinds of havoc. Some players like to set the cutoff of the high-pass filter substantially above 40 Hz or so (keep in mind that frequency is about the frequency of the fundamental of the E string) in order to deliberatly remove some of the deep bottom end along with the infrasonics.

    A notch filter is a combination of a high-pass and a low-pass filter section arranged in "band-reject" mode. It is designed to attenuate a narrow band of frequencies. This is useful for eliminating feedback because feedback is often produced by a resonance at one particular frequency or a small band of frequencies. The idea is get rid of those troublemakers and keep everything else. Here's an example. Suppose you have a high-pass filter set at 1200 Hz and a low-pass filter set at 800 Hz. The high-pass filter will allow all frequencies above 1200 Hz to pass, the low-pass filter will allow only frequencies below 800 Hz. If you add the outputs of these filters "in parallel" then the only frequencies that will be eliminated would be the ones between 800 and 1200 Hz.

    For more, look here and here and here.

    Hope this helps.
     
  14. thejumpcat

    thejumpcat thejumpcat

    Sep 30, 2007
    metro-Detroit
    Uh...now I feel like a drummer. Just kiddin'. Thanks for the info! Sounds like just the ticket for keeping my Kay from howling like a banshee. I'll check the EA website -- unless you know if the iAmp has these features.
     
  15. Jeremy Allen

    Jeremy Allen Supporting Member

    Mar 18, 2002
    Bloomington, IN
    1 dB is not nothin', though, and the difference between 500 watts and 400 watts is also not insignificant. There's something weird about the Acme cabs; they just sound better and better the more power you run into them. The maker once mentioned he thought it was absurd how much wattage people were dumping into them, but in my experience it makes a difference. My Eden WT400 sounded great with the Acme, but it would overheat every night when I was Rocking Down To Electric Avenue (and Then, some nights, Taking It Higher, depending on the mood). Maybe that's a question of headroom or current capability or whatever; my Neanderthal solution was to just get an iAMP 800, which could bring on the noise without breaking a sweat. (Said Neanderthal impulse is the same one that kept me away from the parametric EQ...that, and the fact that the stage was dark and there was beer being spilled everywhere on everything.) There was a noticeable improvement in tone with the iAMP, which of course could be the result of a thousand things; but from a psychoacoustic standpoint, it felt like the amplifier had more control over the speakers at ridiculous volumes, and when it was super loud it didn't feel out-of-control as well. (Kind of like the whole "arm strength" thing with NFL quarterbacks: it doesn't have to do with just being able to throw the ball 70 yards, but it means being able to control exactly where the ball lands when you do throw it that far.)
     
  16. Jeremy Allen

    Jeremy Allen Supporting Member

    Mar 18, 2002
    Bloomington, IN
    I don't think the iAMP has a notch filter or a hi-pass filter, but I think you can do about the same thing with the robust EQ section that comes with it. Doctor?
     
  17. bolo

    bolo

    May 29, 2005
    Apex, NC
    FWIW - Many times I used to cut the Bass knob down to like 9:00 on my Series I Contra. But now that I am familiar with the way the HPF works on the Focus 2R, I think I can safely say these controls effect the bass frequencies in different ways. I definitely prefer the effect of the high pass filter. It seems to tighten up the sound and still leaves plenty of meat as someone else once said. I set the HPF at 70 Hz, and all my bandmates seem to be able to hear me more clearly, especially note length and articulation for some reason.

    I also emailed John Dong at EA once when I was freaking out about the Wizzy speaker cone dance I observed once (when the lighting was just right) in a loudish blues band rehearsal. He said to try a cut at the low end of the lowest band of the parametric EQ. I think this is what Jeremy meant. Well I tried it, but right away I didn't like what it did to my sound. Of course your ears and your mileage may vary. In hindsight, I think now that a HPF would have probably cured all that infrasonic clutter and not altered the overall sound the same way. But I can't explain why, at least not real well.

    A sloped dropoff vs. shelving? I dunno.

    As you said I'm sure the good doctor can try and help explain this better and button it up.
     
  18. MrLenny

    MrLenny

    Jun 10, 2006
    So. N.H.
    Acme B2, Eden 400 sounded OK but did not cut it for Rock ,dance music. SPL 93.
    Bought an Eden XST 2x10. SPL 104 WOW!!!. Too bad the Acme is so inefficient.
    It is a great cab & design. Andy should offer 2 types of cabs. He really knows his **** when it comes to design.
     
  19. drurb

    drurb Oracle, Ancient Order of Rass Hattur; Mem. #1, EPC

    Apr 17, 2004

    Sounds to me like you switched from a 400-watt to an 800-watt amp. That's a 3 dB difference-- still small but noticeable. I do not question for a minute your experience. I do not mean to be argumentative in the least-- but--

    If one takes a 400-watt and a 500-watt amplifier that are otherwise identical, then the difference really is just about insignificant, from the point of view of physics and psychophysics. It's only 1 dB. Whatever the 400-watt amp could do, the 500-watt could do one decibel higher. It seems intuitive that if you've got 100 more watts, you've got more margin before severe distortion and clipping set in. In fact, you do-- but only 1 dB worth. Considering the waveforms we amplify and the way the ear works, it's a virtual spit in the ocean.

    There are so many other factors involved. For example, one can take two amplifiers rated at 400-watts and get very different results driving a particular cabinet. The two amps may differ in their headroom, current capability, damping factor, etc. Let's take current capability. What is often overlooked is that the impedance ratings on cabinets are "nominal" values. This is, after all, impedance and not resistance. That means it is a function of frequency. The actual impedance changes with the frequency being amplified. If a particular cabinet's impedance drops within some frequency region, say from 4 ohms to 2 ohms, then the current required from the amp to maintain the same wattage into that cabinet must increase by a factor of 1.414 (square-root of 2). One amp may be able to handle that, another may not. Current capability is recognized in the audiophile world as being quite important.

    All this is to say that if you find that a 500-watt amp works much better than a 400-watt amp into the Acme it doesn't mean it is because the latter delivers more continuous power. The "greater control" over the speaker you experienced with the iamp could very well be related to damping factor (I won't even start with that here) or better rejection of infrasonics.

    A montra of mine (as you may know) is "Think SPL, not watts." That 's important when evaluating a rig. I could start another one, "Think about watts in terms of decibels." If people would do that, they'd save a bunch of money.

    Salesman: "Oh Mr. Allen, we have a special today at BassCrazy Sound. I can offer you this 650-watt amp for just $200 more than our 500-watt model."

    Jeremy: "Are you crazy? Why would I lay out $200 more for 1.1 dB?"
     
  20. drurb

    drurb Oracle, Ancient Order of Rass Hattur; Mem. #1, EPC

    Apr 17, 2004
    Well, not really. Here's why. The filter sections of the EA parametric "EQ" are bandpass sections that can be boosted or cut. The closest you can get to a notch filter would be taking one of those bands, setting its center frequency (with the slider) to the frequency you want to notch out and turning the knob to insert a decrease in level. The problem is that the notch would be quite wide (at least a 1/2 octave) and wouldn't be all that deep.

    As for the high-pass filter, that's even more futile. The best you can do with the iamp is to cut a bandpass region around 40 Hz or so. That's really unsatisfactory. There's just no substitute for well-designed high-pass and notch filters.
     
  21. Primary

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