agedhorse

The Yamaha powered speakers are actually quite good, BUT you are right in your assessment of how power and maximum SPL are derived. I am (mostly) familiar with how these seemingly incredible numbers are derived and as you suggested they are too good to be true in the context of the bigger picture of pro audio (at least the pro audio industry that I grew up designing in). You have to look at the actual specs and it will become more clear: The clarity becomes more obvious when you recognize that some years back, Yamaha shifted from their own in-house solutions (which were pretty good but did suffer from some reliability and support issues) to what I consider the gold standard SMPS/class D solution provided by ICEPower. They are using the 700AS2 power module, which at 4 ohms delivers between 800 and 850 watts RMS with only one channel driver (the LF channel) because the HF channel load is virtually zero for all intensive purposes. Since I have run extensive testing on this family of modules and was actually one of the beta evaluators of the module (back when I developed the original Subway D-800 in 2014). The continuous power rating is 850 watts RMS for the LF and 100 watts RMS for the high frequency (limited within the DSP), for ~950 watts RMS system power. Now, taking the peak power of 950 watts rms (Ppeak - 2x Prms) and you have 1900 watts peak, rounded up for "dynamic" marketing speak modifier) and you have 2000 watts "peak dynamic power" For the SPL calculation, they clearly say maximum PEAK SPL, so doing the calculations backwards using peak metrics and IF Yamaha is using peak for SPL as 4x RMS (customary in passive consumer PA speakers) that yields a speaker of 100dB/1W/1M calculated with no power compression assuming it was an unpowered cabinet. The problem with the above is that we are 3dB too high because program power is a made-up number, peak is really 2x the rms value, the cabinet now must be 103dB/1W/1M PEAK SENSITIVITY for this calculation to work out. I would easily believe 100dB/1W/1M (this really is a pretty good speaker with reasonably premium components) but I wouldn't take 103dB/1W/1M at face value without more investigation. Since we customarily use (in my world) or used to use (the marketing world) RMS metrics for sensitivity and SPL, correcting to RMS metrics yields 100dB/1W/1M average sensitivity which is awfully high but "possible". My better guess would be 98dB/1W/1M real world but I don't have one to test. Therefore the CALCULATED maximum average SPL for this speaker will be somewhere between 133dB/950W/1M (assuming they calculated using the 4x multiplier that the prosumer audio folks tend to favor. My educated hunch is that it's between 130 and 133dB but I don't have all of their spec footnotes. I do these calculations an awful lot, it's pretty easy to see what's going on when you live it.

I was unaware of this, hadn’t seen it in other products. I will have to explore this more to see who does and doesn’t do this.

Actually, most manufacturers use 1W/1M for their sensitivity metrics, not 2.83V. This gives more easily comparable sensitivity figures, especially when a manufacturer offers the same cabinet in 4 and 8 ohm versions. With the Ampeg maximum SPL figure, ~3dB of the gain comes from low frequency mutual coupling and ~3dB comes from double the power handling.

I agree. There’s nothing inherently wrong with using subs, and in reality the power alley thing is greatly overblown in most smaller indoor situations. It’s actually overblown in general, it’s just one of the tradeoffs that a pragmatic pro audio provider deals with on a day to day basis. The greatest benefit is to use subs for low frequency extension, to take the pressure off of the top cabinets to provide that extension. They do not have to be used to add “boom” to the system.

It comes down to “the quality is proportional to the cost”.

This is one of the reasons I have stuck with ICEPower for all of my designs. There were many Asian vendors that made great promises yet every one of them had significant questionable elements with their offerings. Ultimately it made more sense to pay a premium price for a premium product.

Not at all very elaborate. The values the caps are labeled as and what specs they are built to can be entirely different. Below is a far more elaborate "mis-labeling" than a simple printed number:

You are putting a lot of faith into numbers that can be totally made up, or perhaps mean nothing.

Why not? A used amp is a used amp unless somebody’s already attempted to repair it or modified it. Every amp is a used amp once it’s been used.

It’s not creepage/clearance that’s the issue. Mains plugs have to withstand reinforced insulation creepage/clearance at 375Vpk (240V high line peak voltage) whereas the insulation requirements for a speaker jack needs to be designed around basic (or possibly functional) insulation values based around no more than 150Vpk. I don’t have my tables handy, but I would guess creepage required for a speaker connector is under 5mm, maybe as small as 3mm. It’s more the touch-proof requirement for higher powered amps as well as temperature rise under high current density conditions which can cause arcing conditions (PIS).

No, not that I am aware of. They are not “touch-proof” jacks, and are easily confused with DI outputs. They are also not rated for the necessary current, something that safety regulations have addressed through terminal temperature rise.

For clarification, the Streamliner also operated the tubes at 300V.

Yes, RMS would be 1/2 of the peak value, making it 125 watts RMS into 8 ohms and 250 watts RMS into 4 ohms.

The Magellan pre is a full, complete preamp. It’s designed to drive a power amp or effects return of a bass amp. Because it is a preamp with the function of bringing instrument level signal up to full line level, bypassing the preamp defeats the primary and principle job that the preamp was designed for. Most comprehensive preamps have already evolved to top mounted jacks, this is becoming the standard which makes sense given the number of connections. Even in the guitar world this is becoming much more common.

Not getting any sympathy here! Preparing some racks for another season on the road: