Q: I own the zv28 mk1 and am looking at the newer version. The specs on max SPL are listed as a few different values depending where you look but the MK3 says 137 db when the MK1 said 142 db max SPL. Has this changed? If so, why?
A: I always resisted making claims about "peak" output, but when our gear was being added to websites like Guitar Center and Sweetwater, they had text fields that needed to be filled with those numbers. All the peak numbers I'd seen published by "the competition" were unrealistic. They were numbers based on calculations, not measurements.
The trouble was, if we published measured output, it would seem that our speakers were nowhere near as loud as "the competition", and we heard plenty of questions about why our boxes were not as loud as but more expensive than "Model ABC". The truth is that they were easily as loud, if not significantly louder, but we provided SPL figures that were measured with crossovers on and limiters engaged, exactly as the boxes were delivered to the customers.
Other companies would publish SPL figures that could only be achieved outside of the subwooofer operating band. Even worse, most published SPL figures based on calculations using the sensitivity of the drivers and the theoretical maximum output of the amplifiers. These claims were impossible to realize because they didn't take into account the excursion or thermal limits of the drivers, nor the fact that the amplifiers often were similarly over-specified. In other words, they were the "WLS" numbers. When Lightning Strikes, and you have access to that 1.21 gigawatts, this might happen...
Nevertheless, we needed to provide some point of comparison for all those web shoppers who weren't going to read the kind of long and involved explanation provided above.
So we compromised and included a "Peak SPL" figure that was directly comparable to the numbers supplied by "the competition" and added an asterisk that led to a short version of the explanation above. Here's what it said:
*Peak output is calculated using “industry standard” techniques. These calculation methods create theoretical specifications that are inflated over what can actually be achieved. BASSBOSS real world output specifications are provided as “Maximum Sustained Output” ratings, which reflect actual measured, continuous output levels.
As I said, I never liked publishing those numbers, even with that disclaimer, and since the speakers were now more widely available, the reputation better known and, probably most significantly, they were being delivered and demonstrated to the salespeople by our new distributor, the question about SPL was readily put to rest with in-person experiences. For the reasons above, when the time came to produce the new specifications for the Mk3, we decided to eliminate the "calculated" peak output specifications.
As a final note, although the amps have changed, you'll see that the continuous output SPL has not. This is because the output SPL is constrained by the excursion and thermal limitations of the drivers, not the amps.
The really noticeable improvements between MK1 and MK3 are in the ports, which are bigger and longer and less restrictive, allowing higher SPL at lower frequencies. This doesn't improve peak SPL, but it improves how much SPL is available in the 23 to 36Hz range. (If you like that sort of thing...)
Thanks and best regards,
David Lee