14 hours ago, acg said:

Room boost below the lowest mode due to a sealed room...the new room is open thus not so much free spl from the sub.

Not "below the lowest mode".....  but yes, due to (I would suspect) the sealed room they were designed for, vs the open room here.   There could also be other factors contributing.

22 hours ago, frednork said:

All good, This is how the sub was setup initially. It is a bit rough and ready and only has an analogue xover in front of it to sum both channels and steepen the xover curve. The plan is to dsp it as a single speaker initially to house curve and then at a alter time when I have all the bits to dsp  the sub and mains separately.

That looks ok.

 

To be clear in my other post, what I am suggesting is simply

 

Try the big subwoofer in other locations if you can

Add a small subwoofer with. a narrow bandpass as "active treatment" for the 50Hz mode.

L2  treatment vs L3 5 sq m  RPG absorbors  behind listening position

 

Sorry bout the mess

 

 

 

ok lets have a look at impact on amplitude response

 

Ok this is making a difference.

 

what about RT60

 

 

significant impact above 100Hz

 

Spectrogram

 

 

 

So a nice reduction in RT60 and spectrally an evenish reduction across the board above 100Hz

 

400ms is still higher than I like so there will be more.

 

Edited February 16, 20233 yr by frednork

1 hour ago, frednork said:

listening position

Ima just goin keep derailing your thread 🤣  (until you say no, of course)

 

Can the LP be out from the wall?

Can you do a specrtrogram with the mic out another 1.5m vs where it is now?

 

Of course it probably can't for daily living .... but you can easily setup two profiles on your signal calibration.

 

1 hour ago, frednork said:

above 100Hz

Nice effect at ~150Hz in the 50 to 100ms range.... which is part of why I am interested in moving the LP.  

2 hours ago, davewantsmoore said:

Ima just goin keep derailing your thread 🤣  (until you say no, of course)

 

Can the LP be out from the wall?

Can you do a specrtrogram with the mic out another 1.5m vs where it is now?

 

Of course it probably can't for daily living .... but you can easily setup two profiles on your signal calibration.

 

Nice effect at ~150Hz in the 50 to 100ms range.... which is part of why I am interested in moving the LP.  

I can but although it doesnt look it its already 1.85m from the wall and the rooms only 5.1 deep

3 hours ago, frednork said:

I can but although it doesnt look it its already 1.85m from the wall and the rooms only 5.1 deep

Photo perspective, fooled again.  🤣

 

Hmmm... maybe it would be too close then.

But I am really strongly of the opinion that most of the time, most people don't sit close enough to their speakers, and too close to back wall.   I would try it if you can.

Ok heres a vid comparing the sound between L2 and L3 and also plays the null result. Just in case you are wondering why thats interesting it is the difference between the 2 files. Assuming I have taken enough care in the recording it is the difference between the 2 treatments that has been removed. Later I will compare the delta's to see what we can see there

 

 

Edited February 16, 20233 yr by frednork

I did the first null just by manually lining up the files in Audacity. It seemed ok. When I tried that for the L2-3 comparison I found I couldnt get a convincing sounding null and wasnt sure whether to include it. I then remembered one of the guys on ASR had developed an app specifically for this purpose. Its called Deltawave. It worked very well. you can find it here https://deltaw.org/. Its got a lot of tools which I havent investigated yet but looks like it could be really useful.

 

One cool thing I found in it is this thing called a comparator. So if you are wondering, can I really hear the difference between these 2 treatments it will set up an abx blinded for you. I struggled a little whilst I got used to it and till I found a good telling bit but 98% confident is good enough for me. FYInterest the bit I focussed on to hear the difference was the high hat. Its more slurred in the L2 version

 

L3  treatment vs L4 2 x RPG BAD panels at first reflection

 

 

This will be interesting for a few reasons. Its only 2 panels so good luck to me picking which is which in the abx!! Also the LX521's being dipoles have much lower output at first reflection and infact that is how they are recommended to be setup so the effect of 1st reflection is less anyway..

 

Oh well not every change can be massive!!

 

Here is the amplitude plot

 

Its definitely not massive

 

Heres the RT60

 

A small benefit - its only 2 panels after all

 

And spectrogram

 

At least you can see it!!

Edited February 17, 20233 yr by frednork

Aaaaaand heres the vid

 

 

And can I tell the difference in ABX? surprisingly yes. I did this a few times and it does take a fair bit of concentration but just doable. This time the hihat was not working for me so was listening to how muted or ringy the snare was

 

Edited February 18, 20233 yr by frednork

Ok, this is the last addition of treatment. (for now anyway) and I have combined 2 locations of treatment as its dragging on a bit.

 

 

 

Level 4  treatment vs L5  2 x RPG BAD panels behind speakers and 3 ish absorbers in side room

 

amplitude comparison

 

small differences but I made this one using variable smoothing to show that there were somw differences below 100. Might be a clue that this is the area that is causing problems.

 

RT60

a reasonable reduction in T30 times pretty broadband,

 

and the spectrogram

 

things are still improving.

 

 

Edited February 18, 20233 yr by frednork

And the full set

 

 

ETC shows some nice differences too

 

 

Group delay generally gets better too

 

 

Clarity too

 

 

and waterfall

 

Theres a few odd things going on around the 1-200 mark at the noisefloor. It make be just extraaneous noise around the house at the time or...? Also that big lump that appears at around 25Hz, Maybe passing car or helicopter or something.

 

And the spectrogram

 

You might think great! job done, big improvement. It is greatly improved and from not very enjoyable to very enjoyable. Problem is I know it can be better.

 

I might try putting the bass cabinet on the floor, and also see what other listening positions might bring  as suggested earlier in the thread.

 

 

Edited February 18, 20233 yr by frednork

Fantastic to see the progression @frednork

 

1 minute ago, acg said:

Fantastic to see the progression @frednork

 

Now if I only had some of those gnarly damped mass traps of yours.....

2 minutes ago, frednork said:

Now if I only had some of those gnarly damped mass traps of yours.....

 

I'll send you the design if you want to build them...they ain't inexpensive to build though.

4 minutes ago, acg said:

 

I'll send you the design if you want to build them...they ain't inexpensive to build though.

Might wait till living arrangements are a bit more permanent before I consider that.😬

 

Edited February 18, 20233 yr by frednork

I forgot to add I also dsp as well. This is an early dsp effort. I will post final later but you get the idea

 

 

 which improves flatness of curve (and sounds much better). 

 

ETC is much better especially in the 1st 3ms or so

 

 of course step response is more ideal

 

 

On 17/02/2023 at 11:25 AM, frednork said:

Aaaaaand heres the vid

What's this music?   It's reminds me of if the Red Hot Chili Peppers were stoned in their practice room.   🤣👍

I love this track. Its from one of my failed careers, this particular one as a music producer. It was for me something to practice my recording skills on and for them a chance to rehearse a new band concept called Lounge Deluxe. Its a bunch of excellent Melbourne musos. Bill Wall, Shane Ryall and Chris Paraha. I dont remember the name of the track. I spent an hour setting up mics etc, They worked out the structure for 5 minutes before this take and then just ripped it out.

 

Here is the whole thing (crappy clip is my fault)

 

6 hours ago, frednork said:

from one of my failed careers

Ahhh.   Very cool.   I like it.

 

6 hours ago, frednork said:

this particular one (crappy clip is my fault)

Ok, thought you were legit trolling us when the cat came on.

👍

 

6 hours ago, frednork said:

recording skills

Yep.  Is good.

Ok, another thing I was going to mention is what is a good RT60 target? Well if you read things like this forum and others you might say anything from 200ms to 600ms.  Reason is that room size and reflectivity vary and so "optimal" RT60's do vary also and just to add a final gazumper to it all, It also depends on your taste. Ok, so anything goes clearly. 

 

These are just some random thoughts I have on the topic. I havent done anything to prove what I say but am just putting it out there for you to consider it and see how that might fit or challenge your ideas on the topic. Am sure some will come in and tell me how wrong I am.  All good. Not sure how you will convince me longer times sound better tho. To put my cards on the table I think somewhere around 250ms or slightly more for a typical domestic room is ideal for me.  I just think it sounds better and I like to hear reverberation in the recording more than the reverberation created by my room and the longer your times get, the more your room is masking your recording. And it will mask the sound of the space in the recording.  Even if it does sound nice to you.  The other thing that is not mentioned at the same time often enough  is that your reverb times will influence your house curve, as, if your high frequencies are bouncing around for half a second there is a lot of extra high frequency energy and conversely, if you highly damp your room, there is a good chance your room will sound dead and lifeless as that is all gone. If you are doing this without considering eq ing . I would say you probably wont like it. But setup properly it can reveal more inner detail and more spatial information. And it can sound good!

 

Something else to think about is the vast majority of studios are highly damped and this is where the music you listen to is created and mastered in. I dont know of any that run 500ms plus rt60's.  If you want to hear it as it sounded in the studio a 600ms rt60 will never allow that. I guess I am talking about stereo reproduction specifically but it could be argued that for 5,1 and above your rt times should be fricking short as you are using multiple soundsources to create the soundscape and you dont need support from the room to create that as you might want in 2 channel.

 

It is true the designer of my speakers posited that 450ms was an ideal rt60 and I do wonder about that. He was trying to say that with his speakers which offer a higher direct to reflected ratio than monopoles the effect of reflections were less on the perceived listening.  One benefit of which is that lower room reverb times are not as important, so indeed at 450ms the Linkwitz speakers will cope much better with room reflections than monopoles that fire of a lot of energy to the sides and I think this was the point he was making. Also I think that it depends on the music you listen to. If you predominantly listen to classical recorded in concert halls the reverb times are much (hugely) greater than those in a damped studio and 150-200ms might not make that much difference to the sound of those recordings and maybe make it sound more real. I dont know. 

 

So I guess I should revise my previous outrageous 250ms target and say depending on the music you listen to. But still not sure about that.

 

What am i going on about with this direct to reflected stuff? The following is a bit from Linkwitzes website which talks about it from the perspective of monopole vs dipole. But he also says you can achieve the same result with monopoles but the listening distance needs to be much closer and the room less reverberant. whole thing is here https://www.linkwitzlab.com/listening_room.htm

not everyone agrees 😜

 

 

Ok so what do recording studios sound like

 

This https://users.aalto.fi/~ktlokki/Publs/mst_laukkanen.pdf   is a nice thesis which explores that question and more

 

In conclusion it says

 

"Finally, the results of the listening tests and their connections to spatiotemporal visualizations were discussed. The results of the preference tests clearly showed that mixing engineers prefer quite dry rooms (T60 of 0.15 - 0.20 s) and interviews confirm that the stereo image and the amount of room reverberation are the most important factors for them. In contrast, mastering engineers seemed to prefer more lively rooms (T60 of 0.30 - 0.40 s) and the frequency balance was the most important factor for them. It was also noticed that the preference rating varied between different music samples, especially among mixing engineers. Concerning the specifications for an ideal control room, it seems that the earlier studies are mostly in line with the results obtained in this work. However, there are several factors to be emphasized. Firstly, the accuracy of the stereo image was experienced very important by almost every mixing engineer in this study. Secondly, the optimal reverberation time seemed to be yet shorter than earlier studies showed. Finally, on the basis of the listening tests, it seemed that different music genres need different kind of treatment in control room."

 

I like it of course because it agrees with my own preferences, others may not think it is so accurate.

 

One very cool thing they did was to capture the impulse of various studios and then reproduce it in their anechioc chamber described below to allow instant comparison. Many engineers recognised their own studios using this method.

 

"To enable A/B comparison between different control rooms, sound field of each measured control room was auralized in an anechoic chamber. Listening system consists of 30 Genelec 8030A loudspeakers assembled in 3D-space. Figure 19 illustrates the loudspeaker positions used in auralization. Each music sample was convolved separately with the corresponding 30-channel SDM responses for left and right channel, respectively. In this work, each SDM-encoded sample was played back from the nearest loudspeaker with respect to the arrival angle."

 

 

Love it!!.

 

Ok next, how can we predict how to get to our desired rt60?

Ok, so how do we predict how much treatment we need to get to our desired rt60? I can say I have no idea how to do that but this relatively new tool purports to do so https://amcoustics.com/tools/amrev/#/room

 

its a bit half baked atm and you have to do all the work and none of it can be saved. So if you accidently close the page or your computer decides to restart for an update (Frikin windows I am looking at you) then you have to start again. but it may be very useful once it gets better.

 

What you do is enter your rooms current RT60 and then the characteristics of the treatment you are wanting to use and then you can add the treatment virtually to give an end result.  I compared its prediction with what I measured and its close enough I reckon. There are some issues with how absorption is specified and the frequency range that is shown in specs but once you take that into account its pretty good.

 

So what about targets. It has some standard targets included which are customised for your size room

eg https://tech.ebu.ch/docs/tech/tech3276.pdf

 

 

 

 

or DIN 15996 - Feb 2006, chapter 4.6.5.2

 

 

 

Lets see if i meet these and what it would take to get there

 

 

 

Well the easy answer to do I meet it is a big NUP. not that far off. With this standard (DIN music) I cant meet the below 100 Hz without some serious trapping so will focus on the >100Hz for now.

 

With the treatment types I have on hand  can I achieve the standard. (above 100hz anyway)?

 

 

It says I can meet it down to 160 Hz with an additional 6sq metres of absorbor which equals a bit over 8  120cmx 60 panels. This is where the roof would come in very handy. Sadly its a rental so canno do. If I add more absorbors it doesnt affect things at lower frequencies so no point.

 

What if I add more Abfussors which have more impact at lower frequencies?

 

 

Ok I can meet it (to 100Hz) with 4 more Abbfussors. Considering their size and cost that aint happening. This is a stupid standard anyway😁

 

What about EBU? of course as it is atm it doesnt meet that either so what extra is required?

 

So with 13 extra Absorbors I can achieve the above that is really getting into padded cell territory.

 

Just for fun lets go all out

 

 

ok looks good, gets me down to a little below 50Hz

 

but would take around 13 absorbor panels and 16 BAD panels both of which are 120cm x 60cm each. OMG

 

The nice thing about this is it becomes obvious pretty quickly that just applying broadband treatment in large quantities may not give the most efficient result and targeting your issue with the right kind of treatment is a good idea!

 

Hope theres some things to ponder for you...

 

 

Edited February 19, 20233 yr by frednork

@frednorkExcellent stuff.  I'm firmly in the low reverb time camp.  With the horns my room was about 350ms (from memory - this could be off a bit) and higher in the bass and sounded really very nice, but putting 10 of the big VPR's in the room with their steel panels has really changed the sound for the worse.  Without measuring things (on my to-do list!) I swear the bass reverb has tanked and is very low but the mids and treble reverb is so much longer now...not great!  So much bass texture and nuance...but also way too much high frequency energy.

 

The VPR's are completely un-skinned, and the next move is to measure the room and try to figure out what acoustic properties the VPR skins will need.  Theoretically this should all be 200Hz and higher absorption, which is way easy to provide, and some diffusion too.

 

Having a room that has lower reverb at 60Hz than 5kHz is certainly unusual.  My approach has been to nuke the bass reverb as first stage of room treatment with second stage matching the remainder of the frequency range to the same reverb time.  I should start a parallel thread to this one...

Oh, I forgot to mention, but I don't think you can add too much bass absorption into a room because of the energy and wavelengths involved, but you can absopb too much mids and highs.  My goal is even reverb times from 40Hz to 20kHz and as close to 200ms as possible.  Will see with time if that is possible.