[freefall-fast]

Question on GR Research speaker measurement videos' AKA Spectral Decay, Off Axis and Freq Response, is their a video explaining what the heck those pics are? For rookies like me, those crazy graphs are confusing.

[Hobbsmeerkat]

The on-axis response is the volume at a given frequency measured at 1 Watt, 1 Meter from the center of the tweeter.
Ideally, you want a flat and smooth of a response as possible with no major peaks or dips.

Horizontal off-axis starts with the on-axis response with the speaker being measured when turned 10° away from the microphone, getting further off axis with each measurement.

Vertical off-axis starts with on-axis but the microphone is instead raised 4" for each measurement.

Spectral-decay shows how fast each frequency rolls off within a 4ms gated time window. The faster the drop off the cleaner the sound will be. Ringing/stored energy will show as a streak that rolls off slowly.

In the last video about the Vienna Acoustics Mozart & Mozart Grand.



With the Mozart Grand, there's a lot of stored energy in the woofer response at 1200Hz as a slowly-decaying trail, while most of the tweeter response falls off really quickly.

The long trails come off as "smearing" and can also lead to harshness and fatigue, depends on where it falls within the spectrum, especially within upper mids the lower treble.

Danny also has a video about measurements:
https://youtu.be/ZBz3Tj-MHuo
https://youtu.be/XK38MZXn4mA

[freefall-fast]

Ummm ok, I just see a thing that looks like a tidal wave coming at me, LOL

[Tyson]

A perfect waterfall plot would look like a giant rectangle - straight across the top (from left to right) and then straight down, top to bottom.  Any bulging you see in a waterfall graph is bad.

[g3rain1]

A perfect waterfall plot would look like a giant rectangle - straight across the top (from left to right) and then straight down, top to bottom.  Any bulging you see in a waterfall graph is bad.

Shouldn't it be a frequency dependant slope?  You can't expect it to, and wouldn't really want it to, roll off faster than 1/f.

[Shives]

I would toss up a decay of a good speaker and a bad.

Good speaker decay won’t have any of that waterfall line coming towards you! The more of those lines, bigger they are, further they come towards you, more ringing, more noise, more problem.

If you look at GR- web page you’ll see under some of the speaker upgrade kits, before and after of the decay, and how Danny fixes them.

Again, hard to see without both side by side. But in the end, you don’t want any of those fingers coming at you, towards the bottom of the graph. The further they go out, the more milliseconds of ringing… or when they inject a signal to the speaker, this is the left over tones that bounce around.

So, that graph for a good speaker should not go past .5-1.3 staying level with the rest. But towards left hand of the screen/graph.. you’ll see lower frequency’s that get trapped and make the box, or speaker basket what ever vibrate or ring. You don’t want that… right hand side of the graph is what you want. Left is not.

[Shives]

This below is the stock RP-600 you’ll see off to the left side the fingers or waves coming towards you a bit more.


This is after the no res and such for the same speaker. You’ll see the fingers or ringing down come out as much. Or, if you compare these graphs to the ones about you’ll see a clear difference! The larger the graph, more waves, more trapped sounds. Or, left over tones after signal has stopped.

[DannyBadorine]

This below is the stock RP-600 you’ll see off to the left side the fingers or waves coming towards you a bit more.


This is after the no res and such for the same speaker. You’ll see the fingers or ringing down come out as much. Or, if you compare these graphs to the ones about you’ll see a clear difference! The larger the graph, more waves, more trapped sounds. Or, left over tones after signal has stopped.

But with these two waterfalls, it seems like the first one is better above 1KHz.  Below 1KHz the first one is slightly better.  Are they swapped?

[Hobbsmeerkat]

But with these two waterfalls, it seems like the first one is better above 1KHz.  Below 1KHz the first one is slightly better.  Are they swapped?

No they are correct.
The new trails in the 2nd are small enough that they can be ignored, its the longer trails that reach closer to the 4ms at the bottom of the graph, that are the bigger issue.

[DannyBadorine]

No they are correct.
The new trails in the 2nd are small enough that they can be ignored, its the longer trails that reach closer to the 4ms at the bottom of the graph, that are the bigger issue.

Copy that!  The upper register stuff is barely different so that makes sense.

[Danny Richie]

I explain a lot about measurements in this video: https://www.youtube.com/watch?v=fmcngRdm4kg&t=314s