Acoustic Panels and Bass Trapping a new lounge

[playdough]

On 26/01/2024 at 9:21 AM, DVDHack said:

The BoM predicted a dry hot summer, so a lot of work went into fire prep, then we had a wet summer,

That's reasonable news for the Farm, although a lot of work. Grass is still green at my place, mowing all Summer as well.

A lot of work went into those diffusers, really good job. 

I've been thinking  about how to measure the horns outside. 

The system is tidy enough to get onto other things like HF speaker room calibration to the level of the JBL's, re made some disappearing  shelves and organise the cables, cut up blackwood door and coffee table top  finished with Duratex.  Nothing other than speakers sitting on speakers, except cd's. Happy, the rack is on wheels, inc the cd player monitor and PC..

I installed a wire from the ground plane of the amps to the ground termination  on the DSP, didn't change anything.  The amp rack has had a few weeks to settle in and it's very nice and well behaved all round and no trouble. I thought about using speaker cable risers 

The idea was to hide everything and make it modular. Today it's finished, hardware aspect of the job.

I think I'll forgo the record player in this case. The OPPO is nice, won't get sick of cd's any time soon. 

So yea, back to  work on a kitchen that needs some form of acoustic treatment and is a month overdue to be finished, the time slips away ! 

Edited January 30, 2024 by playdough

[Charson]

Those speakers really reminds of the Ascendo Black Swan speakers.

[playdough]

On 01/02/2024 at 3:33 AM, Charson said:

Ascendo Black Swan speakers

Hi Charson yea, they certainly look similar indeed. 

294-6060--bc-speakers-dcx464-8-spec-sheet.PDF

Coaxial HF, very interesting has no idea these existed thanks for sharing.

 

https://josephcrowe.com/blogs/news/b-c-dcx-464-16-with-es-600-biradial-horn

 

Edited February 1, 2024 by playdough

[playdough]

So had a quiet moment and a coffee.

Tried unsuccessfully initially a few weeks ago,  pairing the Iphone and I Tunes, via a BT connection to the minidsp Flex 8, was a tiny disappointment at the time.

Worked it out.

Found  I had to switch to BT as the source input the Flex, Initiate  BT pairing and hold it manually  in that state  until the I Phone had completed it's "handshake". Otherwise it won't pair. Took around 10 second button press. If you let  the Flex BT pairing  time out, it won't be long enough for the phone to pick it up and act like a dud.

 

The I Tunes runs in "Lossless" mode and the outcome is rather good via the BT, another mystery solved and another source for the system. Not as nice as the CD Player, but you literally have to have listened to the cd and know it. Some streamed media is ok, some is not so.  

I use noise cancelling headphones,  I Tunes and the phone at work and now pairing the lounge system.

Went and saw the girls at Spotlight who found some speaker grill cover type of material acting as a black drop cover for the dusty black horns that are nightmarish things  that like dust. 

 

Just waiting on a compression driver replacement so as I can get onto the PSE horn measurements, driver is in the mail.

 

 

Edited February 5, 2024 by playdough

[almikel]

On 30/01/2024 at 1:35 PM, playdough said:

I've been thinking  about how to measure the horns outside. 

What are your thoughts on this?

 

I've been contemplating for ages (but never implemented) a measurement rig that would attempt a decent measurement of my PSE's on top of my TD18s for a DEQX "speaker measurement" of the combined PSE + TD18 as a single speaker.

My proposed measurement rig would look like this:

A bit different to the measurement rig used at @Listener's place for the PSE when Alan from Deqx visited

 QLD - photo here:

 

I can't easily place a mic that far away ...

At the time of this measurement I did try and convince @Listener to drag a TD18 up onto the scaffold to measure, but I wasn't successful 

 

I've got some ideas on how to increase the speaker to mic distance with my proposed rig, but still likely less than @Listener's rig.

 

Taking measurements of the TD18s operating 50-350Hz will likely include some reflections - the key will be choosing what corrections to make...

 

 

cheers,

Mike

[playdough]

Hi Mike

Cheers for the post, really interesting.

There are a few options around my place here as the topography of the location is quite steep, Across the road from my place there is a large empty park.

I have a little 4 channel chip amp that can be battery powered and a laptop so power supply won't be a problem.

Back yard is no good, has a 3m fence around it and is reflective acoustically, plenty of fruit trees loaded this time of year.

I have a pair of speaker tripods that could be made taller no problem for the Umik1 and it seems to work ok on 10m of USB extension cables. Long speaker cables no problem.

If all that fails there is a kids playground on the waterfront that would do, might be a bit of a spectacle however.

I think the park across the road is the go, one quiet night  Set up on the retainer wall a short speaker stand and mic in the paddock. 

I'll make it fun as I can and try some off axis measurements by moving the PSE144. THe 21's can stay in the lounge, I have a theory on those after the last try, been thinking about that.

 

 

[almikel]

With any measurement of a speaker, the further the distance to any boundary, the better.

Realistically, you always have boundary reflections included in your measurements, so the key is what you choose to correct or ignore.

 

In any of your options, try to get your PSE's as high as possible above the ground - as the ground in your scenarios is always likely the closest boundary.

 

On 07/02/2024 at 11:28 AM, playdough said:

THe 21's can stay in the lounge, I have a theory on those after the last try, been thinking about that.

"in room" measurements likely the best approach 

 

Another approach for measuring subs is the "ground plane" method (ie 2 pi space).

With no other boundaries close, other than the ground, place the sub on the ground and the mic on the ground 2m away, and the measured response is a close approximation to the free field (ie 4 pi space) response at 1m.

 

A bit off topic...

For anyone that doesn't understand what I mean by 2 pi vs 4 pi space, it's a term used in spherical geometry and crosses into audio when subs are placed in a room.

Steradians are the unit of measure for solid angles in 3 dimensions - similar to degrees (and radians) used in 2D space...think radians on steroids to get steradians...likely not funny if you've never heard of radians either  (engineers mostly use radians instead of degrees)

 

fun fact: scientific calculators have buttons for degrees (DEG), radians (RAD), and gradians (GRD) - Gradians were an attempt to metricise degrees - 100 gradians in a right angle and 400 gradians in a circle - it never took off....

...fortunately the rest of the metric system did

 

A 4 pi steradian space is free field (full space) - no boundaries anywhere - not typical except in anechoic chambers.

A 2 pi steradian space (half space) would be a speaker on the ground in an open field, with no other boundaries other than the ground.

A pi steradian space (quarter space) would be a speaker on the ground next to a high wall, with no other boundaries other than the ground and the wall.

A pi/2 steradian space (eighth space) would be a speaker in a tri-corner

reference: https://www.trueaudio.com/st_spcs1.htm

 

Apologies for the off topic - but I think it's good information to know.

 

Mike

[playdough]

Been a bit quiet just to have a listen. Let the dust settle and just live a little.

Sold the record player ,,,,,,,,,,,,dunno if I'll regret that however, nothing wrong with a very nice CD player and what's available online, so that's how things will be from 2024 on.

The vast collection of records, they go next.

The Stereo here has remained unchanged other than a few in room EQ changes, refinement mainly. Novelty has not worn off.

A remote test rig is almost realised for REW and the UMIK1  some out door measurements will go ahead as time permits, no hurry

 

On 09/02/2024 at 12:31 AM, almikel said:

Apologies for the off topic - but I think it's good information to know.

 

Never a problem @almikel The Engineering speak takes some digesting !! 

Sorry for late reply, been out making some coins for the balance of this house renovation, almost done inside and gearing up for the next stretch of "building" 

 

Cheers

playdough

The PSE144's have a new pair of matching compression drivers so they are sounding like they should,,,,,,,end of game is nigh with this set up, so on to the next one in the actual sound lounge, under the house. 

 

 

 

 

Edited February 26, 2024 by playdough

[playdough]

On 09/02/2024 at 12:31 AM, almikel said:

Fun fact: scientific calculators have buttons for degrees (DEG), radians (RAD), and gradians (GRD) - Gradians were an attempt to metricise degrees - 100 gradians in a right angle and 400 gradians in a circle - it never took off....

...fortunately the rest of the metric system did

Mike the walking audio encyclopaedia. I bet you are in some really complex Engineering roll and practically speak another language at work. 

 

[DVDHack]

On 9/2/2024 at 12:31 AM, almikel said:

fortunately the rest of the metric system did

Well it did in civilised countries.

[playdough]

@DVDHack How is the little wooden assembly going ? 

The grass is only just starting to dry out here, stopped growing flat out.

Weather is fairly stable and haven't noticed anyone feeding cows. A little rain every couple of weeks, enough to make it humid for a day.

Cheers 

 

 

[DVDHack]

Little wooden assemblies?  No one has described them like that .  See photos, can't easily get wide enough to get them properly in frame.

Need to still install the absorption in the bottom and cover with material.

 

 

 

Edited February 27, 2024 by DVDHack

[playdough]

54 minutes ago, DVDHack said:

Little wooden assemblies?  No one has described them like that .  See photos, can't easily get wide enough to get them properly in frame.

Need to still install the absorption in the bottom and cover with material.

 

 

 

Mate, must be such a nice thing to sit down and  listen to. You have made a special effort there.

[almikel]

40 minutes ago, DVDHack said:

Little wooden assemblies?  No one has described them like that .  See photos, can't easily get wide enough to get them properly in frame.

Need to still install the absorption in the bottom and cover with material.

 

 

 

wow - are they a pair of N37 2D QRD's?

seriously impressive !

 

1 hour ago, playdough said:

Mike the walking audio encyclopaedia. I bet you are in some really complex Engineering roll and practically speak another language at work. 

Not really  - although I do love science and have an electrical engineering degree...so not too far off!

I flipped from engineering to IT 25 years ago and now spend my work time explaining to management why they should spend money on cyber security, and replacing IT infrastructure before it runs out of support...so my role is translating IT language to management language to justify enough money to keep things running/grow/implement new solutions etc  

 

Mike

 

[DVDHack]

8 hours ago, almikel said:

are they a pair of N37 2D QRD's?

Im not sure what N37 defines.  I used this site to calculate the layout and sections.  http://www.oliverprime.com/prd/index.php  Enter Block height Q as 2cm, block width as 3.2cm and low frequency at 400Hz, block count is 156(12,13).  I made 12 of those, 6 on each side.  Those calcs result in a max 420mm block size.
 

I also installed 4 BAD panels under the material on the cloud units, I may do a few more yet.  
 

You can't see behind but I have corner panels the same as the front.  I will be going one block height higher at the front and they will be doubled up.  At the rear I will build 400mm deep panels with BAD panels across the front.   I had the BAD panels CNC routed into 5mm MDF.

[playdough]

@DVDHack

Really lovely what you have done in that lounge, What sort of main speakers are those, looks like a coaxial HF Driver in the top there ?

 

Good time of the year for 2 wheels at every opportunity. Stereo has been faultless. Considering the power amps are close to 30y/o. Low voltage power equipment has a habit of being long lived and ultra reliable.

[DVDHack]

3 hours ago, playdough said:

Really lovely what you have done in that lounge, What sort of main speakers are those, looks like a coaxial HF Driver in the top there ?

The speakers are TAD R1TX.  I'm really enjoying the room.  Bit to go but with my health progress is a bit slow.  When the acoustic treatment is done I have one final concern.  The chair I use is a leather recliner that extends over my head, I'm wondering if the leather reflects in my ears and if I'm loosing some of the ambience from the back wall.  I'll try another seat and see if it makes a difference.  I'd welcome any input if someone has gone through a similar thought process.

 

My gear is now final so I'm just tweaking the room and the setup now.

[almikel]

On 28/02/2024 at 6:23 AM, DVDHack said:

Im not sure what N37 defines.  I used this site to calculate the layout and sections.  http://www.oliverprime.com/prd/index.php  Enter Block height Q as 2cm, block width as 3.2cm and low frequency at 400Hz, block count is 156(12,13).  I made 12 of those, 6 on each side.  Those calcs result in a max 420mm block size.

Lot's of work there - well done!

Your reference link goes to a site for calculating Primitive Root Diffusers (PRD).

I'm more familiar with Quadratic Residue Diffusers (QRD)...commercialised by RPG (Cox and D'Antonio)

 

...both PRDs and QRDs diffuse, but I'm unsure of the technical differences between them.

 

For QRDs, the N number is the prime number the diffuser is based on...ie the number of wells before repeating the pattern eg N3, N5, N7, N11, N13, N17, N19, N23, N29, N31, N37

...I looked at your photos (clearly not that carefully) and didn't identify any obvious repeats, and came up with a well count of 37 on 1 side....again maybe not correct...but that's where I got N37 from.

 

From your post, 

On 28/02/2024 at 6:23 AM, DVDHack said:

block count is 156(12,13)

I'm guessing your diffusers are N13 in 1 direction and the pattern is repeated - which is fine.

 

From my understanding of QRDs (not PRDs !), primes are important to achieve diffusion - I don't understand why the site you linked to gave a design of 12 x 13 instead of 13 x 13 ???

 

In the scheme of things, it likely makes no audible difference, but with QRDs theoretically 12 wells can only achieve diffusion based on the largest prime divisor ie 3 (N3).

 

I'd be surprised If this doesn't apply to PRDs also - you likely have less "diffusion" in the direction with repeated 12 wells than you thought...

 

Obviously too late now to change your existing diffusers, but if you decide to build more, I would recommend the free tool QRDude https://www.subwoofer-builder.com/qrdude.htm , an amazing free tool for designing/optimising QRD 1D and 2D diffusers.

 

Both 1D and 2D QRD diffusers are always based on prime numbers to achieve diffusion...

...repeating patterns are fine...but can introduce "lobing"...ie strong peaks 

...Cox and D'Antonio recommend using an "inverse" pattern panel...or just rotating a panel 90 degrees to reduce "lobing" effects.

 

Mike

[DVDHack]

5 hours ago, almikel said:

From my understanding of QRDs (not PRDs !), primes are important to achieve diffusion - I don't understand why the site you linked to gave a design of 12 x 13 instead of 13 x 13 ???

its too early to read through this for me but I did a quick skim.  You seem very interested in the design aspects so you might like a read of this https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/5401921.  It's the patent the site is based on.  For my purposes I was looking for the best I could find design for the first reflection position.  I doubt my room or my ears are yet at the point where I will notice deficiency.  I won't be building any more at this stage, they are very costly to build and take a big effort.
 

The other diffuser I use is based on the RPG BAD panels, they look like this 

 

 

I had the routed in 5mm mdf.  They will go over the top of the absorption panels yet to be made for the rear.

 

its an interesting journey but my objective isn't to become an acoustics expert, I just want to get the maximum value from my equipment investment.

 

Ill be glad when its done.

[almikel]

On 01/03/2024 at 6:04 AM, DVDHack said:

You seem very interested in the design aspects so you might like a read of this https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/5401921.  It's the patent the site is based on.

Thanks heaps for that! - I'm very interested in the technical design aspects of all things audio!!

Fascinating read...although I've also just skimmed...clearly I need to learn more about PRD diffusers!

 

The key takeout from my quick read of the patent is that 2D PRD diffusers cannot be square...the "well count+1" needs to be prime, and each direction needs to be coprime (ie no common factors >1) - which is the case with your PRD diffusers - well count of 156 (+1 = 157 which is prime), and 12 and 13 have no common factors >1.

 

On 01/03/2024 at 6:04 AM, DVDHack said:

I doubt my room or my ears are yet at the point where I will notice deficiency.

I don't think there is any deficiency just based on my reading of the patent - PRDs may have better diffusion performance than QRDs, especially from a repeated pattern/lobing perspective.

 

On 01/03/2024 at 6:04 AM, DVDHack said:

I won't be building any more at this stage, they are very costly to build and take a big effort.

I totally get that - your PRD's are awesome and way beyond what I would DIY!

 

On 01/03/2024 at 6:04 AM, DVDHack said:

The other diffuser I use is based on the RPG BAD panels, they look like this 

I love the concept of BAD panels!

For me, BAD panels are what you use as a mask over existing room absorption if while adding sufficient absorption to control your room's bass response you've made your room "too dead" and want to bring some treble back into the room, but with some diffusion.

 

Unfortunately, it's hard to find good data on where diffusion starts and stops with BAD panels compared to say Quadratic Residue Diffusers (QRDs), and likely Primary Root Diffusers (PRDs).

I have an old thread linked below attempting to clarify the diffusion specs of BAD panels:

My takeout is that if you want "actual" diffusion use QRDs (or maybe PRDs?)...

 

...if you've managed to control your "in room" bass (yay!!), but through the process absorbed too much top end - adding BAD masks over existing absorption IMHO is an excellent way to bring treble back into the room, with some amount of diffusion.

 

1D BAD masks are very easy - just slats over absorption in a 1D BAD pattern (coin tossing works fine - heads=slat, tails=gap)

The cheap 2D BAD panel approach is just adding another layer of slats in the other direction (90 degrees).

The 2D BAD panel hole mask design like RPGs takes a bit more maths.

@hochopeper wrote an algorithm to generate a 2D BAD pattern any size - refer page 5

but I haven't seen Chris ( @hochopeper ) here on SNA for a while  

 

cheers,

Mike

[DVDHack]

9 hours ago, almikel said:

I love the concept of BAD panels!

For me, BAD panels are what you use as a mask over existing room absorption if while adding sufficient absorption to control your room's bass response you've made your room "too dead" and want to bring some treble back into the room, but with some diffusion.

Mike, that is precisely what happened to me.  I knew nothing about room treatment and commenced, as I expect many do, by placing panels in each corner and a cloud on the ceiling.  To me it was just too dead, but much better than the reverb chamber I started in.  I had already decided to diffuse the rear wall and I decided to start with some BAD panels over the ceiling cloud panels.  I did them one by one until it sounded OK.  Only 6 of the ceiling panels have BAD since the room sounded good at that point.

 

I'll post pictures of my rear absorption with BAD panels as I build them, they'll be 400mm deep.  The panels freed up by this build will be redeployed to double up the front corners and go a row higher.

 

Last night I placed an order for the BACCH4Mac software, see how that fits into the system.

[playdough]

So on goes the renovation

Just finished the worst job I  was dreading, floor re finishing.

So the 70y/o suspended hardwood floor was a bit of a mess, but in the end is finished. 

The house lot of goods, slowly coming back in from the yard.

Moved the rig, installed 8 Sorbathane bumpers in the end on each cab, much better. 

Big job

Cabinetry is next with 20 Queen Anne Tas Blackwood doors total, should get them in next. some plumbing and the last couple of sheets of lining, only a few weeks to go, month probably.

One of the plans is to fill each second overhead with a bass trap  the pantry trap is still on the cards. Most of the materials to fab it is here on site,

 

As the job goes on, may as well acoustically treat the whole area, or for this config in the space. I like it, looks great more symmetrical in the space  and would likely mean I go looking for some swivel wheels for the couch.  The listening area is 1.5m longer with the speaker position as it is now.

looks somehow smaller, the speakers

I'll pop up a few photos as it all goes together, should be a treat, the kitchen/lounge is starting to come together.

 

 

Edited April 15, 2024 by playdough

[playdough]

If someone had of said I could operate my system 10 years ago with no source cables, I would have been sceptical. 

BT Headless, sounds ok.

Edited April 16, 2024 by playdough

[playdough]

Bass line is a house shaker ,,,,,,,,,,,,,, confession of a self admitted bass addict.

 

 

[playdough]

Opps, while cleaning up another 8 channels of Power Amps has been located, and dragged out from  under another bed

It's on again, system 2   Big job this time, have to make the horns and enclosures ! 

@Grizaudio might be able to supply the coaxial compression drivers. Feel free to PM if you can advise or supply as I see you as the "speaker Guru" all knowing  about such things speaker tech.

That solid copper back, dual PS Alpine Amp is a very limited special edition, designed for competition and a rather nice amp for voice and HF section, that will run the coaxials.

Edited April 30, 2024 by playdough