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Good idea/Bad idea?

Discussion in 'Amps and Cabs [BG]' started by Bob DiGiacomo, Jan 16, 2012.

  1. Bob DiGiacomo

    Bob DiGiacomo

    May 6, 2007
    I have read this forum for probably 5 years now and I have learned a ton about how amps and cabs work. It is so great to have so many knowledgable people on here. Just so happens, I would like to get some advice from those people.
    About 10 years ago I purchased an Acme Low B2 4 ohm. I paired it with a Peavey 115 BX BW 4 ohm. I was running a couple of different preamps into a Mackie 1400i. It worked pretty well, i could balance the cabs with the sensitivity knobs on the power amp, plus the Mackie had hp filtering at 30 hz. I even used the crossover in my Peavey Max pre for a while to run the 115 as a sub (about 250 hz and below). That rig pushed some serious bass.
    Well, fast forward to today. I now live in NYC and don't currently own a vehicle. Let's just say I had to downsize a bit. Still own the Acme. Love the clarity. Bought a Genz ShuttleMAX 12.0. Along the way I acquired an old Genz 115 cab. This is the closest I can find on their site, but I think mine is even older as it doesn't have the edge lift handles. It has two 1/4" jacks and no markings or writing whatsoever other than the Genz Benz badge on the front.


    It was 8 ohm but I swapped the 4 ohm black widow out of the peavey cab and sold the peavey cab with the 8 ohm GB speaker. I now regret this, but I'll get to that in a second.
    These days all my gigs are pretty much one cab gigs. Lugging one of these through the subway with a bass is about the limit of my ability. The Acme has been my choice up until recently. I love the tone, the low end extension, but it just doesn't keep up with some of my bands. I was starting to wonder if the ShuttleMAX wasn't all it was cracked up to be as I can make the limit light turn on pretty quickly. I actually don't like the distortion that comes with the overload light as most of the time I just want pure, clean sound. I am a solid state guy. A couple of gigs back I brought out the Black Widow loaded Genz instead. Wow! The ShuttleMAX is not lacking. With that combination I can pretty much bury our 4 piece funk/rock band. Not that I want to but whereas I used to run the master with the ACME at 5-6 with the Genz/Peavey I run it at about 2.5-3.5. The ShuttleMAX isn't even breaking a sweat.
    But all is not perfect. I miss my low B string. That is the best part about the Acme, it makes everything below low E just as powerful (or more so) than the rest of the bass. I miss that. I also miss the upper extension of the mid driver and tweeter. My ideal amp would be one that I don't even notice is there. I want the amp to reproduce what I put into it. If I want more bass I will palm mute and use my thumb. Distortion? I have a pedal for that.
    I am considering swapping out the Black Widow for a different 15". I have been looking at the options on US SPEAKER PARTS - Speakers, Speaker Cabinets, Guitar speakers, Bass speakers, , Woofers, HF Drivers, speaker upgrades and replacement speakers. Eminence Speaker, JBL speakers, 18 Sound, B&C, EV, Tannoy, Peavey, Celestion, RCF, Jensen, Beyma, Fane, P and I have also been reading some of the (relatively) new info on the Acme site. Using Andy's box calculator (http://www.acmebass.com->science->loudspeaker design->Spreadsheet to Evaluate Specific Woofer in Sealed or Vented Enclosure), I have found what I think is a good candidate. The Eminence Beta 15-A.
    Here is why I think this might be the speaker for me. First, it is inexpensive. I could actually purchase this soon. Sadly, new cabs just aren't in the cards right now.
    Second, it is 8 ohms. On occasion I still get to use both cabs. The ShuttleMAX is 600 w into 4 ohms and 375 into 8. I have been using the formula on Andy's site to calculate max SPL.
    Om = (10 x log Pm) +S1, where
    Om = maximum output
    Pm = maximum input power
    S1 = sensitivity measured at one Watt/one meter
    Punching in the specs from the Low B it comes our at approx. 120db. Putting in the specs from the Beta 15 A it is in the neighborhood of 123db. This seems close enough to me that the 15 wouldn't overpower the 2x10.
    Third, it seems to have almost an extra octave of high end compared to the Black Widow.
    Fourth, it has higher Xmax than the Black Widow.
    Fifth, it is about half the weight of the BW.

    Now there are a couple of things I really like about the Black Widow. First, I know I could run totally horrible gain staging, roll it down stairs, and generally abuse it and there is a pretty good chance it will still work. I know from experience. ;)
    Second, it is really aggressive and cuts through a mix nicely as long as you are on the E string or above.

    According to Andy's spread sheet where as the BW basically doesn't do much below 100 hz, the Eminence would give me a nice bump between 60 and 100 hz. I tend to do this bump with EQ anyway, so I think it would be desirable. My Genz cab is at the rehearsal space so I am guestimating a bout 137 liters of volume. I have no idea what the box tuning is but if it is anywhere near other published specs I have seen, I am guessing 45-50 hz. (Let's not get started on published specs.) The extra upper extension of the Eminence might just give me enough highs that slapping sounds ok even without a tweeter.

    So experts, is this a good idea? Maybe one of the Genz guys could chime in with some more info about this cab? Am I asking for more trouble? Insights and advice are all welcome. Thanks for taking the time to read this.
  2. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    IMO, it's a terrible idea...

    Here's why:

    A speaker cabinet and driver are designed together to work as a system. This means that the mechanical and electrical properties of the driver work WITH the acoustic and mechanical properties of the cabinet. This is independant of things like midrange voicing.

    You would need to choose a driver that has the appropriate properties to work together with the cabinet to insure adequate performance. Since you already have the cabinet you would need to modify it to work well with the driver you choose OR choose a driver that works well with the existing cabinet. This is done by solving the TS equations and understanding how these responses translate into real world performance. Again, this is independant of finding a driver with appropriate midrange voicing.

    Just sticking a driver in a box is a crapshoot that can result is a speaker that handles less than the RMS rating of the speaker over much of it's useable range and maybe has greatly increased distortion an lower reliability. There are computer programs that will allow you to model the speaker as a system (for <200Hz) but you still need to understand what all this means or you will be looking at graphs scratching your head.

    You might try modeling a Delta 15A to see if this seems reasonable (off the top of my head it's probably at least in the ballpark), or maybe one of the guys on the forum might be able to give you a hand.
  3. will33


    May 22, 2006
    +1000 to everything agedhorse said.

    Just off the cuff, the Delta15 would probably give the voicing you're looking for, they're a good choice for lower power amps. It's excursion limits however make me say not the best choice for a powerful amp like your Shuttle 12. That amp could basically overdo it with most any single driver cab but, the Beta you mentioned will take a good bit more power in the lows before distortion. Either will give you the midbass bump you're dialing in anyway. That means you'd be able to get more out of it before you hit the farting threshold but you'll still have to watch it with an amp as powerful as yours. The Beta's midrange voicing isn't the same as the Delta but similair enough, you might like it.

    These are just observations/comparisons between the two drivers mentioned. Others may better fit the bill. Much of it is dependent on the box which is still pretty much an unknown. Accurate INTERIOR measurements of the cab as well as INTERNAL measurements of the port(s) are needed for any further intelligent suggestions. Basically more homework is needed to proceed. If charts and graphs are confusing to you, the best description you can give of desired midrange character/treble roll off you can give would be a help. (hard to put tone into words....I know).
  4. You had a Genz 15 with the driver it was designed for. You swapped out and sold that driver. You now have a Genz cabinet that is worthless. That was a big mistake as you now seem to realize.

    As a B2 owner, I am confused about what the 15 was bringing to the table in the first place. It's very questionable if the 15 could keep up with an Acme down low and the Acme couldn't keep up with the 15 in efficiency. This seems to be using the myth that a larger cone will produce more lows.

    I would whole heartedly agree that a single B2 will not cover all gigs. No matter the size, I always use a pair in a vertical stack. My avatar shows my Series one pair. I've never needed more than that although I also own a Series two pair.

    IMO you should contact Genz for a replacement driver for their cabinet and then sell it. Get yourself a second B2 and never look back.

    Edit: As your B2 is 4&#937;, like all of mine, the second will need to be the same. The amp will need to be stable with 2&#937; loads.
  5. The ShuttleMAX could run each channel into a different B2 at 4 ohms each.

    Agreed that you should get a second B2 and not risk messing up the Genz cab further by changing the driver out again.
  6. Cool! That's how I run mine either with a Carvin DCM1000L or Carvin BX1500.
  7. will33


    May 22, 2006
    Good points by BassmanPaul. Flipping cabs and losing the driver was a mistake, look into getting the proper replacement from Genz as an option. Your crossing over, using the 15 as a sub is confusing to me. Your Acme is one of the few cabs out there that has true subwoofer level bass going on, most don't, and don't need it. One of the tradeoffs of the Acme being able to produce it, is lower SPL, simply, less loudness coming out per watt going in. I think, like a lot of us, what you were hearing as deep bass was actually strong output in the 60/80 - 150/200hz region. You can get that with a lot of cabs and will from the eminence drivers mentioned earlier. As far as the uppermid clarity of the Acme, you're going to have to decide how much of that you need and how much you can live without, at least at an appreciable degree off axis. It's one of the benefits of having dedicated mid cones. If you spend most of your time in front of your speaker, and your rig isn't responsible for carrying the room, you can do with less of it.

    Being a subway rider is going to play a pretty big factor in what can meet your needs vs. what you can actually transport to the gig. Perhaps a totally different cab, like the NeoX212 could give you the right balance. A little bulky for public transit but a smaller footprint than the 15 cab, good combination of lows and upper clarity. The addition of some rear wheels and a pullout, luggage type handle would make transport easy. It's really no bigger than some of the larger luggage. I'd advise getting a cover as when you roll cabs like that, the cones are angled skyward. Always the chance of getting caught in the rain.
  8. Them pigeons are becoming better shots too! :D
  9. will33


    May 22, 2006

  10. Bob DiGiacomo

    Bob DiGiacomo

    May 6, 2007
    Thanks for all the info guys. This is exactly the kind of stuff I was looking for. When I go to rehearsal this week I will get some pics of the cabinet. Maybe then we could figure out exactly what model it is and whether or not the stock speaker is available from Genz Benz.
    Under different circumstances I would just buy a second Low B 2 and be done with it. But is looking more and more like I will just have to forgo that lowest half octave. I sure like the looks of this new shuttle 2x10
    Shuttle Series | GENZ BENZ
    Better start saving my pennies.

    That fEARful 12/6 is looking nice too...
  11. Bob DiGiacomo

    Bob DiGiacomo

    May 6, 2007
    Ok, so I understand that it is a bad idea to put a non-stock speaker in this cabinet. Now I would like to find out if Genz still stocks the speaker for this cabinet and approx. what year it is from. Much obliged if you guys can help me out with this. Thanks.

    BTW, I feel kind of dumb that I didn't notice the model # on the back of the cab before. I guess it had literally been years since I looked at the back of the cab. I always plug the cable in by feel while leaning over from the top. And I tend to carry cabs with the speakers towards my chest so the weight is easier to manage. Oh well...

    Attached Files:

  12. I have the same 115 G-B cab and seldom use it. There's no point in screwing around changing speakers in a cab that's too big and heavy to be portable. (I know it's lighter than most 15s, but it's still NOT a "portable" cab IMO.) Moreover, the 15 doesn't do anything for me that my Shuttle T12 cab won't.

    If you're in NYC and have no car, what you NEED is a Shuttle T12 speaker. You will then have big sound, light weight and lovely portability. Big sound, 8 ohms, and that Shuttlemax head will push it beautifully. Just don't blow it out...and you won't need to because the T12 cab can get awesomely loud. You don't need a 4 ohm cab - you need a head and cab that are well matched and portable. If you REALLY need more oomph, get a second T12 or a T210 (2x10) and stack them.

    Here's my Genz T12/T210 stack with a Shuttle 6.0 on top. The docked Shuttle head makes it 37 pounds for one hand, 32 pounds for the other...or drop the cabs onto a folding cart and go.

  13. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    That's an original GB-15 (no tweeter version) and the original driver was a GBE-1560-8. It's no longer available (your cabinet is probably 15 years old or so) but we still service the driver by reconing the original basket.

    Seeing that you no longer have the original basket, you will have to look at other options like perhaps the Eminence Delta 15 series. My educated guess is that the Delta 15A is close enough but the difference will be the loss of the natural midrange voicing that the 1560 had. It was a very special driver in how it handled the midrange.

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