Multiple Acme cabs & b1500 - connection options

HUnt49 · #1 05-05-2011, 01:00 AM

Hi all -

Just picked up another Acme cab - LOVE these things. I scored a B2 (4 ohm) for $150 in great shape!

My current rig is a B4 (8 ohm) and a B2W (4 ohm), paired with a Carvin B1500. I usually use just the B4. The B2 added a lot of lows, and I lost the flat response that I like from the cab.

So, now with more cabs I have options... the Carvin is 1900 watts at 2 ohms.

The question is... how can I combine these beasts to best effect? I'm thinking: vertically stacked b2's, and all-in with all 4 cabs.

Any thoughts on the best way to connect the b1500 and these cabs?

Bob C · #2 05-05-2011, 07:33 AM

Quote:

Originally Posted by HUnt49

The question is... how can I combine these beasts to best effect? I'm thinking: vertically stacked b2's, and all-in with all 4 cabs.

Wait a minute. How many cabs do you have, total? And how are you hooking them up now? There really is no "wrong" way to hook them up, as long as you don't go below the recommended impedance.

You lost that "flat sound" because the B2W has more lows than you need - rather, practically no highs or mids. Also, your 2X10 is "working harder". Its lower ohm load is "pulling more watts" into less speakers.

jeff7bass · #3 05-05-2011, 08:07 AM

Your best option would be to sell the B1500 and get a BX1500, which has two internal amps and a built-in active crossover.
This will allow to set the cutoff frequency for each cab, plus you have a volume knob for each amp/cab. It’s ideal for your cab situation.
The 8 ohm cab will get 300w and the 4 ohm cab will get 450w, but the fact you have two volume knobs and dedicated amps eliminates any problems with volume per cab. The CROSSOVER knob will help you get the tone you want from each cab.

Bob C · #4 05-05-2011, 08:18 AM

I agree that 2 amps and separate voume controls would be advanageous to that setup. I'm not so sure about the biamping part. He could cut out unneeded high information from the B2W cab, but the B4's signature sound might suffer. Put another way, he could be getting the equivalent of 1 1/2 cabs sound out of two cabs.

babebambi · #5 05-05-2011, 09:33 AM

wire the B2 and B2W in serial
so you have a 8 ohm load with the 2x B2

then add the B4, which is also a 8 ohm load

now you have a total system of 4 ohm
in the form of a 8x 10

no need to switch amp
the B1500 is perfect for ACME

have fun

BassmanPaul · #6 05-05-2011, 09:51 AM

You mention "all four cabinets" yet I only see a B4 @ 8Ω, a B2W @ 4Ω and a B2 @ 4Ω. That's three.

Vertically stacking the pair of B2s for a 2Ω load would expose them to the full 1900W from the B1500. That's way too much power for a pair of 350W cabinets IMO. When I was checking out the B2000 I didn't buy one for that reason. There is also no way to attach the B4 into the system without possible damage to the amp.

My choice was the BX1500. Although the 450W @ 4Ω was more than I really wanted, it worked out well with the 4Ω Series I pair of B2s I usually gig with. I run one per output channel. I have the option, with this amp, to add my second pair of Series II B2s for 2Ω and 750W per channel.

Your 8Ω B4 is going to be a bit awkward to add into any system as I see it.

HUnt49 · #7 05-05-2011, 01:33 PM

Yes, 3 cabs- sorry, it was late.

I agree with needing to supply full-range to all cabs; crossovers are not part of the Acme approach. The thought of a dual channel power amp could work.

I know the b2w only adds lows - that's why I'd been watching for a b2.

I agree that there's not a really good way to get all 3 balanced power safely from the b1500. I did find another TBer who was running 2 4ohm b2's with the b1500, and seemed stable. I tried it last night, very cautiously, and didn't perceive any audible farting, even rolling in some subbass frequencies. But 1900 watts into 2 cabs that like to see 500 each does make me nervous long-term.

I may go back to the b4 and add the new b2, leave out the b2w, and see what I get.

The other option for bigger unsupported gigs would be the B1500 running the b4, and my ep1500 pa amp running a b2/b2w on each channel. Behringer claims 450 watts at 4 ohms with that amp, and while I don't know if I buy that, it's been a clean-sounding workhorse of an amp. That's more complex than I'd like.

BassmanPaul · #8 05-05-2011, 02:11 PM

Quote:

Originally Posted by HUnt49

I may go back to the b4 and add the new b2, leave out the b2w, and see what I get.

Again you run into the impedance problem. The 4Ω B2 will take twice the power that will be given to the B4. The B2 will do most of the work and the B4 almost nothing.

If the impedances had been t'other way around they would have been a perfect match.

You could give Andy a call and ask him his opinion of series connecting the two B2s (as suggested earlier). There is always the problem of the two crossovers interacting poorly but I'm sure Andy know his products well enough to know for sure

zombywoof5050 · #9 05-06-2011, 07:38 AM

babebambi has the right idea...put the two 4 ohm cabs in series (for 8 ohms), and then put that series pair in parallel with the 8hm cab for a total of 4 ohms.

BassmanPaul · #10 05-06-2011, 08:31 AM

Quote:

Originally Posted by zombywoof5050

babebambi has the right idea...put the two 4 ohm cabs in series (for 8 ohms), and then put that series pair in parallel with the 8hm cab for a total of 4 ohms.

As I posted, it's not quite as simple as that (what ever is?). Series connecting cabinets with crossovers can lead to negative interaction. Cabs without crossovers are simple to series connect.

zombywoof5050 · #11 05-07-2011, 12:45 PM

Quote:

Originally Posted by BassmanPaul

As I posted, it's not quite as simple as that (what ever is). Series connecting cabinets with crossovers can lead to negative interaction. Cabs without crossovers are simple to series connect.

I didn't know that, thanks for the info Paul.

HUnt49 · #12 06-04-2011, 01:59 AM

Quote:

Originally Posted by BassmanPaul

As I posted, it's not quite as simple as that (what ever is?). Series connecting cabinets with crossovers can lead to negative interaction. Cabs without crossovers are simple to series connect.

Ah - but the b2w has no crossover. Is there a way to work the b2w and b2 into a series config, or is the b2 crossover still an issue?

Thanks for all the input.

By the way - an email to ACME confirmed that b1500 into 2 40hm b2's is no bueno. I know there's a talkbass member doing that, but the boss-man said it's trouble.

BassmanPaul · #13 06-04-2011, 09:22 AM

I would still have expected the B2W to have a crossover. However if Andy says it doesn't he should know.

Yes a crossover in a series configuration can lead to problems.

Your main problem is that you bought cabinets that were available and thought about interconnecting them afterwards. Before you buy you have to consider your system as a whole.

HUnt49 · #14 06-04-2011, 05:19 PM

Quote:

Originally Posted by BassmanPaul

I would still have expected the B2W to have a crossover. However if Andy says it doesn't he should know.

...Your main problem is that you bought cabinets that were available and thought about interconnecting them afterwards. Before you buy you have to consider your system as a whole.

The b2w's run full-range - the highs go in, there's just not much in the way of response for them. There's no low-pass or anything.

I actually bought the B4 and B2W as a unit, and the previous owner (an authorized BFM builder) had wired an out to run the b4 and b2w as essentially a 610, coming somewhere around 6 ohms and change... so it wasn't really a random purchase.

The B2 I picked up just because it was a b2 for $150. I'm usually a lot more planful about such things, but I figured the b2 and b2w could have some good options out there. Your use of the bx1500 has me intrigued - I'm going to look at those or a shuttlemax 12.0. Should be some good used deals float there here sometime.