1 hour ago, Grizaudio said:

 

Application is key. 

 

 

True, dat!  

 

2 hours ago, Grizaudio said:

Maybe alter the playback speed on the video... Set up to x2...

 

2 hours ago, davewantsmoore said:

1.75x speed is the way...  you get used to the "chipmunks" vibe.

 

Sure, speeding up the vid as far as you can (whilst still being able to understand what is being said) will certainly allow me to complete the viewing in a shorter space of time.  My issue of "my speed" - rather than "their speed" - is more that I can jump sentences and paragraphs on a page of text if I think they're waffling on ... but I can't do this as easily, with a vid.

 

1 hour ago, andyr said:

 

Yes, to:

a. minimise the overlap of frequencies being produced by both the subs & the woofers (making the sound cleaner), and

b. relieve the woofers from LFs - thus:

• reducing the woofers' distortion, and
• reducing the load on the amp driving the mains (making them better able to service the mains, without strain).

 

 

If EG actually did make that statement ... I'd like to know when he said it.  I don't think he would say it in 2023 ... with the DSP capabilities we have, today.

 

16 min mark. 

I've read him state it in the past too

5 hours ago, jamiebosco said:

16 min mark. 

I've read him state it in the past too

He does say this, yes.

I think, in his typical style he does protest a bit too much.... and doen't get the point across (or at least scares people in to thinking "a high pass filter is wrong").

 

 

If you add the extra filters .... it certainly doesn't (necessarily, generally) "make the sound cleaner" .... as long as you get the summed response correct between all the sources (like the procedure in the video will help someone do).   Having a larger overlap can be quite advantageous (and I'd recommend trying to do that, with some caveats).    Also adding the extra phase rotation can make the sources harder to sum, with their variable with position, response.

 

High passing mains, is ok though, as long as you get the response you want/need.... some mains would benefit from taking away more of their bass (mains with decent LF response, no so much).

 

Earl says he "relies on the natural low pass response of the subwoofer" (and so only uses a 1st order low pass) ..... but he is generally talking about his subwoofers which are band pass devices (so have an accoustic low pass element to them) ..... more typical subwoofers will extend usually very far up in frequency, and might still flat at 600 or more Hz.   This would not be good.

 

It's all about getting the response you want/need.

 

Overlapping the mains can be good.

Avoiding steep filters (if you can) is also generally good in this region.

 

So unsurprisingly Earl has good advice.... but we just need to be senible/contextual about it (and understand why he says what he does).

 

Edited May 28, 20232 yr by davewantsmoore

32 minutes ago, davewantsmoore said:

 

Unsurprisingly Earl has good advice.... but we just need to be sensible/contextual about it (and understand why he says what he does).

 

 

 

1 hour ago, andyr said:

Jamie (via Earl) is correct in his response to you though....  there is no fundamental need to match the crossovers, either frequency or slopes in this region....  as long as the summed response is ok.    ie. they sum constructively over the range you want (or conservatively, if you require, destructively -- although less likely to be what you want) ..... and overlapping the sources is mostly a desirable thing (again if the sources are summed correctly..... if they're not, then "keeping them apart with a distinct crossover" would make them sound better).

I hate to be the bearer of bad news but a T20 test is not an RT60.. they are completely different beasts!

 

 

If you want an RT60 test in REW then follow my procedure here

 

 

 

On 12/04/2024 at 7:44 PM, Allan said:

I hate to be the bearer of bad news but a T20 test is not an RT60.. they are completely different beasts!

 

 

If you want an RT60 test in REW then follow my procedure here

 

 

 

Thanks Allan, I will see if I can dig out some of these old results and try your instructions to compare the result.

I'll also do a bit of research to understand the difference between the T20 and RT60, its been a while since I looked at all this stuff.

 

Cheers,

Russ

T20 = time to decay 20dB x 3

T30 = time to decay 30dB x 2

RT60 = time to decay 60dB

The RT60 differing because it will better measure decay curves that bend or are non linear. If the room is noisy and a 60dB drop is difficult to capture use a T30 or T20.

 

In all instances test start times commence once 5dB of decay has occured, so for an RT60 test it will require 65dB of total decay

 

 

Edited April 15, 20241 yr by Allan

On 15/04/2024 at 5:17 PM, Allan said:

T20 = time to decay 20dB x 3

T30 = time to decay 30dB x 2

RT60 = time to decay 60dB

The RT60 differing because it will better measure decay curves that bend or are non linear. If the room is noisy and a 60dB drop is difficult to capture use a T30 or T20.

 

In all instances test start times commence once 5dB of decay has occured, so for an RT60 test it will require 65dB of total decay

 

 

Be careful of paying too much attention to Reverberation Times (RT60, T30, T20 etc) in our typical small rooms.

The original science of reverb times was developed by Wallace Sabine > 100 years ago, measuring much larger spaces and assuming a diffuse sound field.

 

I've got huge respect for Sabine - measuring reverb in an auditorium with a stopwatch, with his students bringing in more and more cushions.... then creating the science of architectural acoustics from there...but it was based on large spaces, eg auditoriums.

Sabine went on using his science to design the acoustics of the Boston Symphony Hall - considered one of the best sounding halls in the world!

 

Our small listening rooms don't have a diffuse sound field (our small rooms have reverberant modal lower frequencies and specular higher frequencies).

 

The designers of REW know this - hence their multiple options for RT times - use them all as guides to compare different treatment approaches.

 

Even though RT times aren't necessarily scientifically valid in our small rooms, IMHO they're entirely valid to compare before/after measurements when applying acoustic treatment (just don't move your mic or speakers throughout the process of adding treatment).

 

cheers,

Mike