Volume comparison using 2 cabs

[Eagle run man]

I was wondering what to expect using (2) different brand cabs, both 4 ohms and both 2x10's but different specs. Let me explain.

I have a 2x10 Acme cab that I have been using with a Mesa walkabout amp, not the 15" speaker cab it came with, and like it a lot. I have recently been getting together with some old band mates and having some fun playing the old tunes and some newer stuff. Well, because I am what I am I decided I wanted another amp. So I ended up purchasing a used Mesa D-100 plus from a poster on this forum. Well, the urge got to much for me so I ended up calling Dave (think that's his name) at Rev Sound and after explaining what i was doing, meaning music genre, volume, tonal likes and dislikes I ended up ordering another 2x10 cab. Now, I haven't received the cab yet but I got to thinking what, meaning pairing up both cabs, the outcome would be if i did.

The Rev Sound is supposed to be a very high efficient cab and according to what I have read puts out tone wise what you put though it. Now, the Acme is not a very efficient cab but I do like what I hear from it. Therefore, although I think I know what the results would be pairing these (2) cabs, what would in your opinion, be the results.

As for as handling the power the amp can provide at 2 ohms I have no doubt of any problems. I play at moderate sound levels. Shoot, it's actually overkill for what I'm doing now but if I needed more volume, big if, in the future I would have it.

I would like to hear your opinions if you would be so kind on what to expect. It's always nice to hear from people who have been there done that sort of thing.

Thank you

 

[agedhorse]

D-800 or D-180?

 

[Eagle run man]

D-800 or D-180?

Sorry, i meant 800 plus

 

[agedhorse]

Ok, with 4 ohm 210’s, you will need to consider the real world mechanical power handling to avoid damage.

A single 4 ohm 210 is really risky as I don’t know any 210 that can safely handle 800 watts RMS. Even operating in 2 ohm mode, the amp is rated at 600 watts rms into 4 ohms.

Paralleling 2 cabinets is better because the rated power of 800 watts into 2 ohms is split between the two cabinets, but this is still a lot of power for many 2 ohm cabinets. Be sure the amp is set to 2 ohm mode whenever driving less than 4 ohms total load.

 

[Eagle run man]

Ok, with 4 ohm 210’s, you will need to consider the real world mechanical power handling to avoid damage.

A single 4 ohm 210 is really risky as I don’t know any 210 that can safely handle 800 watts RMS. Even operating in 2 ohm mode, the amp is rated at 600 watts rms into 4 ohms.

Paralleling 2 cabinets is better because the rated power of 800 watts into 2 ohms is split between the two cabinets, but this is still a lot of power for many 2 ohm cabinets. Be sure the amp is set to 2 ohm mode whenever driving less than 4 ohms total load.

Thanks

 

[Wasnex]

Acme Low B2

Power Handling 350W RMS​

Mechanical Limit 300W at ~31hz
LF Response to 31hz at -6dB​

Sensitivity 93dB 1W/1m​

​

Revsound RS210

Power Handling 650W RMS​

Mechanical Limit (not stated)​

LF Response 50hz. No tolerance is indicated so I assume 50hz at -10dB​

Sensitivity 99.5dB 1W/1m​

The Low B was designed to play very low. If the RS210 response is -10dB at 50hz, it does not play very low.

The RS210 Sensitivity is 6.5dB higher than the Low B2. If both cabs are the same impedance, they will share power pretty equally and the RS210 will be 6.5dB louder than the Low B2 at all power levels. The actual difference may be more as cabs tend to experience power compressions as they approach their power limits.

With one of each cab, power will be limited to 350W per cab, 700W total at frequencies above the point were one cab becomes mechanically limited. I assume an HPF at or slightly below 50hz would be a good idea for the RS210. This is a guess, the required frequency for an HPF could be higher or lower.

SPL at 350W

Low B2 118.4dB...this is max calculated SPL for this cab​

RS210 124.9dB​

Estimated Combined SPL of 118.4dB and 124.9dB = 128.3dB​

​

SPL at 650W

RS210 127.6dB​

​

Assuming the RS210 can take full rated power to 50hz, it's almost as loud by itself as using both cabs.

The only way to see how well the two cabs play together is to try it.

Good luck!

​

 

[agedhorse]

Except that the pair of cabinets will be splitting 800 watts rms not 700

 

[shoot-r]

The only way to see how well the two cabs play together is to try it.

​

This^^^^^.

Eagle,
Using two different manufacturers cabinets with their different designs (the Acme is rear ported, the Rev is front ported), different cab tuning goals, different speced drivers, different sensitives, ect., will be something you'll have to try to know if the combination works together for your ears.

Odds are the combination will be great, but only you can decide.

 

[Wasnex]

Except that the pair of cabinets will be splitting 800 watts rms not 700

The Acme is only rated for 350W. So the usable power is 700W.

 

[agedhorse]

The Acme is only rated for 350W. So the usable power is 700W.

But there's nothing limiting the power from the amp, therefore the amp power is going to be the elephant in the room and the defining metric for the average player. It's the reason for the qualifiers in my post (#4).

 

[agedhorse]

This^^^^^.

Eagle,
Using two different manufacturers cabinets with their different designs, different cab tuning goals, different speced drivers, different sensitives, the Acme is rear ported the Rev is front ported, ect., will be something you'll have to try to know if the combination works together for your ears.

Odds are the combination will be great, but only you can decide.

Yes, the alignment of the two cabinets and the phase response are almost certainly going to be quite different between the two cabinets which will impact how well they work together.

 

[Wasnex]

But there's nothing limiting the power from the amp, therefore the amp power is going to be the elephant in the room and the defining metric for the average player. It's the reason for the qualifiers in my post (#4).

Yes I agree with both the nature and severity of the problem.

My feeling is it's relatively safe to use an amp that can deliver more power than the speakers can handle, providing the the speakers can easily deliver more SPL than you need. However as volume requirements approach the limits of the amp/cab combination, it's increasingly likely the speakers will incur damage because the user has no way of accurately knowing precisely how much power is being applied.

I will further qualify my SPL work up by saying that the real world SPL that can be delivered is likely to be notably lower than the calculated figures due to power compression. Calculated max SPL for the proposed rig is over 128dB. Perhaps we should subtract something like 3-5dB to have a safer margin.

IMHO, providing the OP does not actually require the exceptional LF extension of the Low B2, he would probably be much better off with a pair of the RS210s and a suitable HPF.

• Calculated SPL of two RS210 with 800W = 131.5dB

If the OP requires extended LF, then perhaps he should get four 8 ohm Low B2s.

• Calculated SPL of four Low-B2s with 800W = 128dB

My experience: I owned one of the Low B2s from first production run. I liked the cab, but felt it had insufficient headroom for my needs. It always got the job done, but frequently felt overly compressed and I had to be careful to avoid clacking the woofer voice coils. So I basically I had run it way too close to its limits. I think I probably would have been a lot happier with a pair.

In comparison, my military touring rig around that time used an Eden D210XLT, which I assume is more similar to the RS210 than the Low B2. Although the Acme's extended lows were cool, I found I did not generally need or necessarily benefit from them. Rather, I had more of an appreciation for the Eden's increased headroom and dynamic range. The Eden was much better at punching through the mix in boomy rooms. So IMHO the Eden was a far better choice for the vast majority of work I did.

 

[logdrum]

Mixing cabs low and high sensitivity, my non numeric experience is that you will only hear the sound coming from the efficient cab. So the 2 cabs you have mentioned here, it will sound like only the RevSound is working and not the Acme

And then human nature is to crank the volume and that is what @agedhorse is raising his concerns even though the math looks good., actually it doesn't look good, we are assuming the user will not crank the master volume, but I think that's where the misunderstanding is. We think that if have the master volume is at 3 o'clock, the amp can't possibly push 800 watts, but it can and probably will. The concern is for peaks and transients which it will pump out beyond 800 watts even if you think you are judicious in your master volume.

Now in my practice room, I only have a 300 watt cab but I never crank the master volume to more than 1/3

I think OP, you may find some sonic character that you like mixing the cabs but the RevSound will dominate, If you want it full and deep then only use the Acme and if you like the character of the RevSound, you might as well just solo it. Remember the guidance above that you can burn them out regardless

 

[el murdoque]

Aside from Agedhorse's legit concerns and Wasnex' impeccable math,

There MIGHT(!!!) be a small advantage with the low end excursion of the Low B.
Looking at those numbers Wasnex provided:

Acme Low B2
Power Handling 350W RMS
Mechanical Limit 300W at ~31hz
LF Response to 31hz at -6dB
Sensitivity 93dB 1W/1m

Revsound RS210
Power Handling 650W RMS
Mechanical Limit (not stated)
LF Response 50hz.
No tolerance is indicated so I assume 50hz at -10dB
Sensitivity 99.5dB 1W/1m

I want to apply some psychology to these numbers by saying I believe the Acme numbers are very much on point - simply because some of them look so bad. This is what you pay for pushing the -6dB down to 31Hz.

And that's where things get interesting.
Let's assume that with 40Hz, we're at less than -6, more like -3.
Lat's further assume that Wasnex' assumption with -10 @ 50Hz is correct, and that the dropoff is rather steep, so we're looking at something like -15 (most likely more) at 40Hz. With those guessed numbers, the guessed difference at 40 Hz would be 12dB in favor of the Acme. With the difference in sensitivity, the Acme would still be 6,5dB louder in that frequency.
So while playing both cabs will in most situations strongly favor the Revsound, because it's a lot louder, in some situations the Acme MIGHT carry the rig for a short while.

I would not do it, because the mix is quite wild and the chance that the result is worse than running one of them solo is too big.

 

[micguy]

The Acme has good bandwidth at low freqs, unlike literally any other bass cabs. It is not as efficient, but…

There’s a familiar cab we are all aware of that, if you just used a quarter of it, it would be a 210 that is less efficient than the Acme. The 810 “fridge” has drivers that, 1 or 2 at a time, are innefficient. But…array 8 drivers, and the array gain is considerable.

If you have an Acme cab, and you like how it sounds, but you want more output, you add a second one. Doing that, you keep the low end, you add 3 dB of efficiency, and you get 6 dB more output capability.

Mixing two cab with very different low frequency cutoffs is not going to give you the best result. There is a LOT of phase shift at the low freq limit of a ported cab - combining two cabs with cutoff freqs that are an octave apart, the polar pattern and resultant responses are going ti be chaotic, with less low end than you’d get with decently matched cabs.

 

[ErnieD]

A very timely thread subject. I am in the process of shopping, in TB classifieds, for a second, used cab to, at times, pair with one of my 8 ohm cabs.

I came across a Acme Low b 1x10 ll. But it was 4 ohms. From one my Mesa 800w heads, that would mean the 1x10 will get about 2/3rds of the power. Correct? Over the 8 ohm, larger 12" or 210" getting the, about remaining 1/3rd watts. Correct?

I've passed on that cab based on those numbers. Then I started thinking, I know, always dangerous,

But could I possibly use my fDeck HPF pedal to connect the 1/4" in/outs of that pedal with my speaker cables between the 8 ohm cab or directly from the amp and dialing back the frequency HZ to the 4 ohm cab? In an effort to protect the 10" cab from the 2/3rds power it would receive?

Yeah, yeah I can feel the eyes rolling, head slapping to my question already. Haha it's just a thought on if that much effort would end with any good or better results for such a pairing?
Ok. Fire away!

 

[agedhorse]

No, your pedal will burn up with a speaker level signal, and it won’t work anyway.

The Low B speaker is not a good choice for any of the 800 watt Subway amps.