ACME v BFM

[The Funk]

I'm looking to invest in some new cabs and I'm trying to decide between a pair of ACME B2s and a BFM Omni15 Tallboy for my main gig rig. (For small gigs I'm looking to get a BFM Omni10.5 Crossfire.)

The criteria so far seem to be transportability, price, perceived loudness and evenness of response (including how low the low frequencies go).

Any advice on this one?

[Kiwi]

Next bass bash, I can bring my Acmes if Nedsbeds brings his Omni's

[chris_b]

[quote name='The Funk' post='72711' date='Oct 11 2007, 11:36 AM']I'm looking to invest in some new cabs ...... For small gigs I'm looking to get a BFM Omni10.5 Crossfire.[/quote]
I haven't got a small rig at the moment and I need one. I'm after sonic goodness at low volumes, so I was going to dip a toe into the water with an Omni 10.5 and see where we go from there.

[alexclaber]

Ask me in 6 months!

If you get a pair of Low-B2s then you don't need an Omni 10.5 for small gigs (I don't think I'd be happy gigging with any single 10" speaker anyway, unless full horn-loaded as in the Titans and then you'd need something else for mids and highs) because you'd just use one Acme for small gigs.

A pair of Low-B2s have 96dB sensitivity, 41-22,000Hz within 3dB, -6dB @ 31Hz. An Omni 15 has 104dB sensitivity, 50-12,000Hz within 3dB, -6dB @ 45Hz. The Low-B2s can handle 700W thermally and about double that mechanically. The Omni 15 can handle 450W thermally and a little more than that mechanically. All in all the Omni 15 should max out a few dB louder but the greater impedance may mean you only get one or two dB advantage. The trade-off is that it doesn't go as low.

My gut feeling is that the Acmes will sound fuller and warmer and more transparent, the Omni will sound louder, more dynamic and more in your face. But don't trust me on that...

Alex

[chris_b]

[quote name='alexclaber' post='72904' date='Oct 11 2007, 03:48 PM']My gut feeling is that the Acmes will sound fuller and warmer and more transparent, the Omni will sound louder, more dynamic and more in your face. But don't trust me on that...[/quote]
My benchmark currently is a GK MB150S that I borrowed. I'm looking for a better version of that, a high quality sound/tone at around 100-150 watts. Won't the Acmes be too much?

[alexclaber]

[quote name='chris_b' post='72917' date='Oct 11 2007, 04:13 PM']My benchmark currently is a GK MB150S that I borrowed. I'm looking for a better version of that, a high quality sound/tone at around 100-150 watts. Won't the Acmes be too much?[/quote]

I don't quite understand - is the GK the combo or the microbass head? Would you be using the GK to drive the Acmes? What do you mean by 'too much' - too loud, too big, too expensive??

Alex

[chris_b]

[quote name='alexclaber' post='72979' date='Oct 11 2007, 06:09 PM']I don't quite understand - is the GK the combo or the microbass head? Would you be using the GK to drive the Acmes? What do you mean by 'too much' - too loud, too big, too expensive??

Alex[/quote]
No, I'm looking for something better to replace a GK MB150. About the same power (150w) but a better tone quality. I was starting with the speaker and the Omni 10.5 looked like a possiblity. I thouhjt that the Acmes would be too big for this.

[alexclaber]

I think we're getting crossed wires here - my comments in my original post were all related to the Omni 15TB not the Omni 10, which is a very different design.

The MB150 is a very very small and lightweight combo with rather limited bass extension, lots of midrange and not a lot of treble extension. It is loud by virtue of its midrangey tone. I imagine an Omni 10.5 will be about as loud with the same power input but with greater extension into the lows and highs. A Low-B1 will be quite a bit quieter but have tons more bottom, midrange clarity and treble extension. A Low-B2 will be about as loud as the MB150 but with the same tone as the Low-B1.

Better tone quality is a bit confusing because I know what I like but you might not agree with me!

Alex

[warwickhunt]

What amp do you intend using?

[The Funk]

Aguilar DB680 pre / Eden WT1000 power amp.

[warwickhunt]

[quote name='The Funk' post='73063' date='Oct 11 2007, 09:08 PM']Aguilar DB680 pre / Eden WT1000 power amp.[/quote]

Ah... so you're not going to be driving any cab with a measly 150 watts. The Acmes do make sense then.

[chris_b]

[quote name='alexclaber' post='73029' date='Oct 11 2007, 07:43 PM']...I think we're getting crossed wires here....[/quote]
Seems so!! My fault! Anyway thanks for the opinion re my Omni vs Acme question. Cheers.

[chris_b]

[quote name='alexclaber' post='73029' date='Oct 11 2007, 07:43 PM'].... A Low-B1 will .... have tons more bottom, midrange clarity and treble extension.[/quote]
Given that a Low-B2 cab needs hundreds of watts to get into "the zone", how much power would be needed for a Low-B1?

[alexclaber]

[quote name='chris_b' post='73140' date='Oct 12 2007, 01:46 AM']Given that a Low-B2 cab needs hundreds of watts to get into "the zone", how much power would be needed for a Low-B1?[/quote]

There isn't really 'a zone', the Acmes sound great with only a few watts. However to reach full volume you need 250-500W per woofer (lead sled amps that can supply 250W per woofer may have as much peak power as lightweight amps that can supply 500W per woofer, hence the variation). If you don't need to get every last dB out of your cab then you can use less - I'm confident that I could use a 100W head to drive a Low-B2 for band practices without any tone or volume problems, and I know of people using low power heads with Acmes for rehearsals and quieter gigs.

Alex

[Bill Fitzmaurice]

[quote name='The Funk' post='72711' date='Oct 11 2007, 06:36 AM']I'm looking to invest in some new cabs and I'm trying to decide between a pair of ACME B2s and a BFM Omni15 Tallboy for my main gig rig. (For small gigs I'm looking to get a BFM Omni10.5 Crossfire.)

The criteria so far seem to be transportability, price, perceived loudness and evenness of response (including how low the low frequencies go).

Any advice on this one?[/quote]
This chart compares the O15 to the estimated response of a cabinet similar to a Low B4. I wish the Low B4 chart was measured, but like every manfacturer save Phil Jones Acme doesn't publish measured charts.



I'd be more inclined to go with a pair of Omni 10s. This chart compares an O10 to the estimated response of a cabinet similar to the Acme Low B2

Edited October 18, 2007 by Bill Fitzmaurice

[alexclaber]

Those plots tell quite an interesting story which is certainly not that far from reality. The plot in the Acme manual shows the Low-B4 at 96dB @ 100Hz dropping to 93dB @ 41Hz and 90dB @ 31Hz, so slightly greater bass extension than your plot. How did you ascertain the curve for the midrange and treble?

Alex

[Bill Fitzmaurice]

[quote name='alexclaber' post='73519' date='Oct 12 2007, 01:55 PM']Those plots tell quite an interesting story which is certainly not that far from reality. The plot in the Acme manual shows the Low-B4 at 96dB @ 100Hz dropping to 93dB @ 41Hz and 90dB @ 31Hz, so slightly greater bass extension than your plot. How did you ascertain the curve for the midrange and treble?

Alex[/quote]
I ran a sim in WinISD for BP102s, which rumor has it the Acme OEM is a variant of, and used that up to 200 Hz. 200 Hz to 2kHz comes from the BP102 data sheet. Above 2kHz is a generic midrange and tweeter. If the Acme driver is capable of going lower than the BP102 it would do so at the expense of midrange sensitivity and extension, but there's no point in further splitting of hairs, the results wouldn't be hugely different.

Edited October 18, 2007 by Bill Fitzmaurice

[alexclaber]

[quote name='Bill Fitzmaurice' post='73523' date='Oct 12 2007, 07:20 PM']I ran a sim in WinISD for BP102s, which the Acme OEM is a variant of, and used that up to 200 Hz. 200 Hz to 2kHz comes from the BP102 data sheet. Above 2kHz is a generic midrange and tweeter. If the Acme driver is capable of going lower than the BP102 it would do so at the expense of midrange sensitivity and extension, but there's no point in further splitting of hairs, the results wouldn't be hugely different.[/quote]

The Acme's midrange speaker is crossed over with a second order high pass at 1kHz. The Acme woofer is specifically designed to roll off smoothly at around the same frequency, so bearing those two points in mind the curve is probably a little flatter than the one you've plotted. It would be nice to see an accurately measured curve on their website as it's one of the few commercial bass cabs that does what it claims.

Alex

[Bill Fitzmaurice]

[quote name='alexclaber' post='73746' date='Oct 13 2007, 08:13 AM']The Acme's midrange speaker is crossed over with a second order high pass at 1kHz. The Acme woofer is specifically designed to roll off smoothly at around the same frequency, so bearing those two points in mind the curve is probably a little flatter than the one you've plotted.[/quote]
Could be, but it's academic once you put it in a real room.[quote]It would be nice to see an accurately measured curve on their website as it's one of the few commercial bass cabs that does what it claims.[/quote]
Considering Andy's candor the lack of charts is a curious omission.

[alexclaber]

The view from Andy:

"I was wondering where he got one of my drivers, and assuming he had the
right driver, what he used for parameters, and how he might have arrived at
a box volume for running any type of simulation. (I discussed with you the
notion of a "virtual volume," which can be vastly different that that
measured with a ruler.)

I hope this curve isn't flying around the internet as any kind of a true
representation of my work. Clearly it's not.

Or to put it differently:

1. different woofer
2. different midrange
3. different tweeter
4. different crossover
5. different tuning
6. different enclosure

Same result?"

Alex

[Bill Fitzmaurice]

[quote name='alexclaber' post='75941' date='Oct 18 2007, 06:45 AM']The view from Andy:

"I was wondering where he got one of my drivers, and assuming he had the
right driver, what he used for parameters, and how he might have arrived at
a box volume for running any type of simulation. (I discussed with you the
notion of a "virtual volume," which can be vastly different that that
measured with a ruler.)

I hope this curve isn't flying around the internet as any kind of a true
representation of my work. Clearly it's not.

Or to put it differently:

1. different woofer
2. different midrange
3. different tweeter
4. different crossover
5. different tuning
6. different enclosure

Same result?"

Alex[/quote]The charts I provided clearly state what they represent. Posting actual measured reponse charts, or not doing so, is Andy's perogative, but if he's all that concerned about how his work is being represented then he should remove all possible doubt. With the proliferation of free response measuring software some one will sooner or later anyway.

[alexclaber]

[quote name='Bill Fitzmaurice' post='75999' date='Oct 18 2007, 02:04 PM']Posting actual measured reponse charts, or not doing so, is Andy's perogative, but if he's all that concerned about how his work is being represented then he should remove all possible doubt.[/quote]

I agree - the sound is so clean and extended in both directions without any obvious peaks or troughs to my fairly sharp ears that I'm sure they'd plot out very well indeed.

Of course the frequency response plots don't tell the whole story by any means - how much more peak power can the Acmes handle in the lows and thus how loud can they get? In my experience if you want that kind of bottom you're not going to find anything louder that is as small. If you're doubling up with two Low-B2s then I think the Omni 15TB will get close enough to that kind of response to satisfy my needs for bottom but I can't see an Omni 10 or two being quite as satisfying. Also if you're just using the one cab and are comparing a Low-B2 to an Omni 10, the latter is significantly larger and although more sensitive cannot put out that big deep bottom.

Alex

[Bill Fitzmaurice]

[quote name='alexclaber' post='76012' date='Oct 18 2007, 09:36 AM']Also if you're just using the one cab and are comparing a Low-B2 to an Omni 10, the latter is significantly larger and although more sensitive cannot put out that big deep bottom.

Alex[/quote]
Unless you load it with BP102s. Not that I'd recommend it, as you'd have less midrange sensitivity, and the Omni doesn't need to use a long throw woofer to achieve adequate LF output. But the option exists.

Edited October 18, 2007 by Bill Fitzmaurice

[alexclaber]

Just to add a little more information to this discussion, apparently the Acme woofer is not based on the BP102 as it has not only a different cone but also a different magnet structure.

From what I've seen from messing with BP102s in WinISD Pro you need a much larger cab volume to achieve the same LF output as the Acmes, so merely loading an Omni 10 with them won't achieve that low frequency output, and even then they only have about 75% of the Xmax of the Acme woofer. And as you say you'd need a midrange driver which the Omni 10 doesn't have if you want to get that big bottom and good midrange from a small cab. And as the Omni 10 is tuned to 50Hz then it won't reach as low whatever woofer you put in. Apples and Oranges.

Alex

[Bill Fitzmaurice]

[quote name='alexclaber' post='76201' date='Oct 18 2007, 04:16 PM']Just to add a little more information to this discussion, apparently the Acme woofer is not based on the BP102 as it has not only a different cone but also a different magnet structure.
Alex[/quote]
Certainly that's possible, you should open yours up and see. But even if that's the case there's only so much leeway with what's possible from a box of a certain size, irrespective of what's inside. Hoffman's Iron Law applies to everyone.
BTW, this is a measured chart of an O10 loaded with BP102s, no tweeter, 1m/1w.