same exact cab?

Electronic loading should be pretty close. The different brand or model of cab may have different response that could add something you like or don't care for. No 410 cab from a different maker will sound just like the one you now have.

 

Exact same box is always the best choice. Other cabs of the same format from the same manufacturer would be what I'd look at next, but it isn't a given that they'll match up well. A different maker's 410 probably stands a better chance of working with your exiting 410 than, say, a 212. But if you can hear both of them together before you buy I'd strongly suggest it.

 

The 410T is a great cab. Id look for another. They are pretty cheap.

 

This question is a good one. Lots of us on a budget got an amp and one cab. Now that we can spend some more cash we discover that the cab we got has been discontinued or is made differently. Buying a full stack is so expensive I guess many TBers have bought just the one cab. There's bound to be a bunch of us with the same size speakers in cabs made by different companies.

 

No, no electronic issue.

 

The ONLY time it could be an electronic issue is a used cab that someone modified, or a miss-build new cab.

 

Different is different. There is no reason why two different 410's would be any closer in phase response than a 410 compared to any other kind of cabinet. Phase response, just like "more lows" isn't predictable based on the size of the driver.

 

One helpful hint is to make sure the two cabs of different builds are time-aligned.
Don't just stack them so the front cabinet edges line up.
You'll want the fronts of the voice coils on the same vertical plane.
Ballpark measure is the front edge of the cones--which still takes some work to figure out.

Otherwise they will be slightly out of phase, and the resulting cancellations can make or break the tone and response.
Two exactly matched cabs stacked so one is an inch behind the other can stink up the room, even though it probably sounds fine where you're standing.

I can't count how many bands I see who stack their PA cabs so the front of the boxes line up with no regard for the fact that they are different brands of sub and mid/high (or just chuck the tops up there any old place!).
An inch or four of set-back to get them in phase would solve a lot of their sound issues, and sub/high is a more forgiving situation than a pair of 410s.

 

I'm not an audio engineer so this is only my opinion, and maybe your statement about alignment of the front of drivers does make a real difference, but I think that while you may be able to measure the effect with laboratory instrumentation, the difference an inch or two, along with all the other variables in a live performance environment, listeners at random positions in a venue would not be likely to perceive the effect of such misalignment. Not trying to start an argument, just trying to learn, and understand more.

 

You might be surprised if you tested absolute time alignment versus being offset by even a small amount. Its like wearing prescription glasses and one of the lenses is off a bit - an obvious difference compared to both being spot on. Of course there will be path length differences regardless but that's a whole 'nother kettle of fish.

 

Foz, you say tested. Do you mean by listening? What about all the other effects in a real world situation. For example, the room will likely reflect sound waves which will reach the listener out of phase with the signal. I am trying to visualize the effect of any misalignment on the various wave lengths of all the combined frequencies of the signal. I expect the long wave length of lower frequencies of a bass would result in a different effect than the frequencies typically produced by a female vocalist, guitars, flutes, etc. I think this could be a very complex topic from a scientific point of view, and would not advise to ignore any good practices, but I think in the real world, most drivers are misaligned, and the listeners still perceive that they heard a good sounding performance because our brain may tend to process the sound to diminish the mentioned phenomena. Not to get too far off topic,. but I know that when scientists have investigated how we perceive visual information, they can demonstrate that humans constantly perceive visual information in the brain that their eyes do not actually see. I wonder if the human brain does the same with the auditory process.

Think about how a large symphony orchestra sounds with no amplification. Multiple point sources of acoustic signals are processed in our brain to sound like pleasant music, when they may likely be measured as having phase cancellations, comb filtering, uneven acoustic energy levels, and such.

Too many variables in live sound to get every nuance covered every time, but good practices should be observed to try to make the best of what will always be imperfect acoustic environments.

Understanding, and education about these factors is a good thing, and I will defer to those who are experts in the field.

I know a lot more about all this than I did back in the late sixties, early seventies, when I played out a lot, (often with horrendous sound quality).

It was still a lot of fun, even in our ignorance.

More on topic:

I have the following similar cabs, (among others): 1963 Ampeg B-15 with JBL D130, 1965 Ampeg B-15 extension cab, don't remember the driver. FlipTops B-15 repro cab, Ampeg PF115LF, Mesa Boogie TL606 with EV driver, and while I don't need the volume of two cabs, I do plan to experiment with combining them one of these days. I do realize sensitivity issues, and such would come into play here, and would have to be considered before actually seriously combining any of them in a gig situation. I bet the results of pairing some of these would not be terrible though. I think the only way to find out would be to actually try it.

Thanks to anyone who can contribute useful knowledge, and wisdom here.

 

Well...this is a first! Being a symmetry phobe, this kinda situation could throw me right over the edge. SERIOUSLY!!!

 

Even though both cabs may be electrically in polarity with each other they will very likely not have the same sensitivity/SPL specs so one will be louder/softer than the other cabinet. If you find that to be the case put the lower output cab on the top of the stack.

 

Some are... and when you really line em up you can really hear a world of difference [and measure it].

Example: In designing a crossover for drivers mounted flush on the same baffle you have to take into account the offset between driver depths - or make adjustments to how the drivers are mounted to make this depth acoustically equivilent. If you don't make such adjustments you get drivers that don't sum properly, like this model of a tweeter and mid driver with no adjustment:



You can hear that dip... its a BFD.

You can make electrical adjustments in the crossover to patch that up - or make a physical adjustment like this*:



Here is an actual measurement of that physical offset arrangement at 0-15-30 degrees [blue-red-green] at 2 meters:



*the physical adjustment here is 66 millimeters