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07-29-2018 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,534
Joined on 05-28-2004

Post #: 1
Post ID: 25015
Reply to: 25015
The ULF cannel for my new listening room.
My Placete preamp was sitting in Idaho for update for a long time, so there was not a lot of audio activity lately. Also, the last few month there was a lot of things going on in my life that severely compromised my audio rotation. It is summer and small kids spend a lot of time outside that request a lot if not my attention but at least presence. The property needed to be open for summer business and there was a lot of work need to be done. The idiot-landscaper destroyed grass at our lawn that required me to learn about the damn grass growing and fix it. I undertook a large construction project in our home that required a lot of planning and supervision, it is still going one and hopefully will be over in a week or two. I fired one of my long term helper and another good long term helper ended up in jail, so with a lot of property maintenance tasks I ended up to involved much more then I would like to. Our nanny tenure is expired and new one need to be acquired. I undertook a major transition from .Net to Golang in my professional life. Amy’s parents moved right next to us, which is blessing and curse. Amy and I decided to change to that dreadful “healthy life style”, whatever bloody thing it is, but hopefully it will keep us available for each other and to our kids slightly longer. I turn 50 years old in beginning of month, I can write a fucking book how I feel about it! Anyhow, there was zillion other things that made me kind of “busy” and there was not a lot of audio in my life during the last few month.  
 
Lately, I go my Placete back, the life looks straitening up and a few last time I had a long listening session in my listening room I recognize that I was so much missing these listening experiences.  The playback is a good shape, the extra 6dB from Placete made is even better. The way how I left playback before was a “smart” setting in my view. The playback do not go too low in term of overall balance, it has solid mid 30Hz, but it has also no “shit bass” when typically “wrong means” are used to squeeze bass out of wrong and bass-impotent topologies.  The lack of bass is not so notable in my current playback.  In fact the bass is quite good in my estimation. What is missing is the last feeling of “weight”, the very specific softness that usually introduced with sub 20Hz response, the softness that warms the whole sonic presentation and make is so fucking palpable!  I had in in my formal listening rooms, I call it ULF cannel (Ultra Low Frequency) and I do not have it in my current listening room. Here is how it was done in my last listening room:

https://www.goodsoundclub.com/Forums/ShowPost.aspx?postID=14457

When I said that that I left my playback in “smart setting” I meant that I did not go for ULF by wrong means. You cannot get any proper ULF by bumping room with LF distortions that come for a running a regular commercial subwoofer. You cannot put a large Sunfire-like topology with tweaked electronics in use. Well, you can and you will get the right SPL numbers under 20 but it will be sound that satisfy only your SPL meter but not you spirit.  
 
So, with this post I am starting to collect my thoughts about the ULF for my new listening room and hopefully as a result, I will have it implemented.
 
Rgs, Romy the Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
07-29-2018 Post does not mapped to Knowledge Tree
rowuk


Germany
Posts 225
Joined on 07-05-2012

Post #: 2
Post ID: 25016
Reply to: 25015
Watch the lower knee
Romy,
you have often advocated the ULF channel not having a sharp lower knee. Maybe something like the Thigpen rotary woofer with response to DC would be worth considering.


Whenever I feel blue, I start breathing again.
07-29-2018 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,534
Joined on 05-28-2004

Post #: 3
Post ID: 25017
Reply to: 25015
Some initial thoughts...
All thinking about ULF are usually centered on 3 subjects: drivers, topology and amplification. Even though these 3 subsets very much intertwined I still would like to talk about it separately. We do presume that we have the proper drivers for proper topology with proper amplification. When wrong type of driver used for a given topology or wrong amplification applied then there is truly noting to talk… 
 
The absolute majority of ULF solutions out there today are different variations of ported enclosures. It is know that I hate any ported bass, including is super expensive implementations. Still, in most of the cases implying bass I am taking about auditable bass that always to my taste has some foreign vowels in it. It is a valid presumption that is a ULF channel is crossed under 20Hz then the auditable port accent might not be heard. Years back Wilson Audio made the XS model with two 18” in a ported configuration that meant to run under the large Grand Slamms. That would be sub 20Hz setting and it something that might be aligned with what I am looking. Still, the large ported implementation similar XS takes a very large box and I do not want to invest my listening room with such a monstrosity. 
 
Also, I need to admit that I have no skills to make a ported design to sound better. Sure I can load the T/S in spreadsheet and circulate the necessary detention and to invest money into better peripherals but my hunch suggests me that it is not how good sound archived. I do not see myself to dedicate much efforts to learn about ported design decisions and its sonic consequences. 
 
Well, there is direction to buy a ready to go bass sections, so call subwoofers. Here is the problem. There is practically no products out there that might be used for ULF application. Most subwoofers meant to be used for auditable range. Let to look at the good commercial subwoofers. JBL for instance use to have a very good driver 2245H with resonance frequency 20Hz, QMS 2.2 and BL21. You can makes a very good sounding ported subwoofer with it serving very nice 30 or 40Hz. As you driving it harder or go lower in a larger room then with xMax 9 mm it is not so useful. JBL replaced 2245H with modern version 2269H, it has FS 28Hz more BL and xMax at sub 20mm. You can drive this beast much harder and JBL made number of new LB section around the driver: MD7, Sub18 and a few others. All of them are ported at low 20Hz and they can handle “some” power abuse at transition slope. This type of solution is also big and I would need to be very careful to enter an auditable range as the Fs is to close. 
 
The seals enclosure are foe sure the kind in my view but having 10-20dB lower out at RS you need a lot of drivers to get some SLP and VERY large box to avoid problem in case internal volume compression kick in. 
 
The horns also out if picture foe me. It might be a good idea to go for midrange horn and use my current LF section for midbass but I do not have in me stamina to unleash myself on another Midbass horn project. 
 
There is a direction that I am looking now – the Infinite Baffle (IB).  It was almost a cream de la cream topology, superbly hard to implement and very had to implement. The funny part is that my new listening room almost made foe IB. I have a very cool second sealing above my listening room and I am considering to put IB in there. With IB drivers need to be able to handle high exertion and a lot of power. I have in my storage 8 Aura 1808 drivers. They are 96dB sensitive, tunes for 25Hz and under 18mm Xmax, the most important is that 1808 undehung! So, I am considering to put 2-4 per channel, in IB configuration, loaded into an open triangle. There are some other options. The AeSpeakers have cool driver IB18HT. It is not underhang but with Apollo update it might be useful. It tuned for 18Hz, 18mm eversion, slightly less BL and less sensitivity. 
 
I will be exploring more IB options during the ways and weeks to come…



"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
07-31-2018 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,143
Joined on 10-12-2006

Post #: 4
Post ID: 25018
Reply to: 25017
"Tuning" IB
The AE cited is said to be "designed for IB".  Since one does not "use the box" or a vent, etc. to jack up IB LF, it's going to be all about moving the 250g Mms through  the usual, steep, ULF filter.  Maybe a notch filter or anti resonance filter at 19 Hz?  Any readers out there running one of the AE IB woofers?



Paul S
08-01-2018 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,534
Joined on 05-28-2004

Post #: 5
Post ID: 25020
Reply to: 25017
Here the way how I planning to do it for now.
Are any commentary from the folks who have done it before?
IB_V1.jpg



"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
08-01-2018 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,534
Joined on 05-28-2004

Post #: 6
Post ID: 25021
Reply to: 25020
Interesting.
I engaged is a discussion about my IB project with some guys who do IB for a while: 
 
http://ibsubwoofers.proboards.com/  , the My Projects Section, I think you need to login to get it… 
 
What is interesting is that they claim that “rubber and foam do nothing to decouple the manifold from the structure” because it will be “tremendous amount of vibration from the sound waves”. I certainly respect what they advise but it does sound not intuitive to me. I know that there are some builder at this forum, what is your take on the subject?



"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
08-01-2018 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,143
Joined on 10-12-2006

Post #: 7
Post ID: 25022
Reply to: 25021
Very Low Frequencies vs. Framing
Romy, does the area behind the drivers open into a sort of attic space?  If the parts of the structure are well fastened together, you get one major resonance.  Depending on the driver behavior it is sometimes possible to "spread" the resonance around some.  But at basically sub-sonic frequencies, expect the house to shake, according to what you're listening to.



Paul S
08-02-2018 Post does not mapped to Knowledge Tree
decoud
United Kingdom
Posts 241
Joined on 03-01-2008

Post #: 8
Post ID: 25025
Reply to: 25021
Composite damping
Low frequency damping is a huge problem in architecture, and that it is poorly solved tells you it is hard. Simplest improvement would be to use a viscoelastic material with better properties than rubber and to embed weights within it. Perhaps obtain a two inch thick sheet of Poron, fire lead shotgun pellets at it, and cut out your gaskets from the result.
08-02-2018 Post does not mapped to Knowledge Tree
rowuk


Germany
Posts 225
Joined on 07-05-2012

Post #: 9
Post ID: 25026
Reply to: 25021
Resonance is only a big issue if you have one point of in phase excitement
If one is using multiple in phase drivers, they are spread out over space and help reduce resonance by interference. Another possibility would be a B&W like lightweight matrix enclosure to move resonance UP, where it is more easily damped. A third possibility would be to mount the drivers in reverse and connect the chassis or magnets. This impulse compensation would dramatically reduce the transmission of energy to the structure!
http://members.aon.at/kinotechnik/diyaudio/dipol/space/impulse_compensation/Impulse_compensation.pdf


Whenever I feel blue, I start breathing again.
08-02-2018 Post does not mapped to Knowledge Tree
anthony
Posts 191
Joined on 08-18-2014

Post #: 10
Post ID: 25027
Reply to: 25021
I am inclined to agree with them...
 Romy the Cat wrote:
I engaged is a discussion about my IB project with some guys who do IB for a while: 
 
http://ibsubwoofers.proboards.com/  , the My Projects Section, I think you need to login to get it… 
 
What is interesting is that they claim that “rubber and foam do nothing to decouple the manifold from the structure” because it will be “tremendous amount of vibration from the sound waves”. I certainly respect what they advise but it does sound not intuitive to me. I know that there are some builder at this forum, what is your take on the subject?


I did not bother signing on to that forum to see your thread, but no foam is going to decouple 20Hz, not even close.  Part of the design criteria of my my Bass Cannons project is to try to limit the transmission of low frequencies through the floor of my room down to the house below.  Speaker cabinets at those frequencies do not attenuate the volume very much and even with my rather inert, damped, very rigid and pre-tensioned Cannons sound leaks through like water through a sieve.  The transmission of sound causes vibrations in the cabinet walls which is then efficiently coupled to the floor which vibrates in sympathy which causes sound transmission to the rooms below.  I looked at all kinds of ways to isolate these speaker vibrations from the floor, but in the end I used industrial pneumatic isolators similar to those you have in you Vibraplanes (but much less expensive).  Part of the reason that I used those mounts is so that I can level the stack of Cannons, but there are other low frequency mounts that you may be able to use if levelling is not required.

Look for the resonant frequency of the mount (Fs) that is sufficiently below the frequency that you wish to isolate above.  Multiply Fs by the 1.41 and that is the frequency from which the isolator will start isolating:  so if Fs = 5Hz then isolation begins at 7.07Hz.  

Have a look at these mounts.  Note that they have specidfied a minimum and maximum load:  to get best isolation you have to load them near their maximum (same with all of these mounts I will link you to).  These are the pneumatic mounts that I used.  Under the DSET power supplies I needed something that was relatively inexpensive but capable of isolating reasonably low frequencies so that I could keep floor vibrations out of the power supplies:  I used these.

I hope this is of some use Romy.


08-05-2018 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 454
Joined on 01-07-2006

Post #: 11
Post ID: 25028
Reply to: 25027
Pneumatic mounts + high mass
As a practitioner of vibration decoupling (stacore.pl), I second the idea. No gel, foam, rubber, etc will work on ULF as high mass + pneumatic mounts do. Pref. pneumatic damped too. I can assist with the design of the suspension.
 
Cheers,
Jarek



Cheers,
Jarek
08-07-2018 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,534
Joined on 05-28-2004

Post #: 12
Post ID: 25030
Reply to: 25028
Something like this...
Romy_2Aura.jpg


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
08-07-2018 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,143
Joined on 10-12-2006

Post #: 13
Post ID: 25032
Reply to: 25030
Driver Load?
It is not clear to me, when looking at the sectional elevation, are we seeing an "exit hole" that is smaller than the sum of the driver diaphragms?




Paul S
08-07-2018 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 454
Joined on 01-07-2006

Post #: 14
Post ID: 25033
Reply to: 25030
Weight
How heavy is the structure to be suspended?




Cheers,
Jarek
08-21-2018 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,534
Joined on 05-28-2004

Post #: 15
Post ID: 25047
Reply to: 25030
The infinite baffle project is underway.
My contractors who built for me the 40Hz midbass horn in my former listening room is doing currently my infinite baffle manifold. The deals was changed, it is not what depicted above and there is no compression chamber in there anymore. It make with 1.5” Baltic birch and it is heavy like hell. If everything will be fine then we will be opining the attic next week and begin to cut the joists to mount the thing in time-aligned position. H, the 4 Aura 18 drivers in that room with half dropped Fs… it will be interesting. Frankly I do not know what to expect from sound…


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
08-21-2018 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,143
Joined on 10-12-2006

Post #: 16
Post ID: 25048
Reply to: 25047
The Other Parts
Is it too soon to talk about amps and X/Os, line or speaker level, active or passive, etc?  If nothing else, it might save years to use a "board" to establish profiles, especially since the speaker positions will be fixed, and there are (almost) always sum and difference issues.


Paul S
09-03-2018 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,534
Joined on 05-28-2004

Post #: 17
Post ID: 25088
Reply to: 25047
The Infinite baffle project goes on in active state today.
Ok, my carpenter brought today two large manifolds for 4 Aura drivers and this week will be installing them. Can’t wait how it will end up sounding...

Infinite_baffle_manifold_Parking.jpg



"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
09-06-2018 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,534
Joined on 05-28-2004

Post #: 18
Post ID: 25089
Reply to: 25088
It is going somewhere....
OK, the first assembly is there. It sits on 3 joists and with the joists are cut, blocked and warped up. The exit is 30.5 inch by 24 inch. It is 1.5” birth plywood.


IB_The_wholes_are_made.jpg

IB_The_wholes_are_made2.jpg



"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
09-06-2018 Post does not mapped to Knowledge Tree
anthony
Posts 191
Joined on 08-18-2014

Post #: 19
Post ID: 25090
Reply to: 25089
Time aligned
Although difficult to tell from the photos, they look pretty close to being time aligned too Romy, by the time you allow for the height of the baskets in the ceiling and their overall height above the horn stack relative to your sitting position.  
09-07-2018 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,534
Joined on 05-28-2004

Post #: 20
Post ID: 25091
Reply to: 25090
Nope, not time aligned.
That was a subject of long consideration for me and I ruled not to go for time alignment. You see, my current listening position is 8.5 feet from the diaphragms and my ceiling height is 14 foot. Let pretend that I am siting at 4 feet at my listening chair then it still not enough distance to get a true time alignment. There are more complications then this. I have 100 inches ceiling fan above me that I would like to keep, I would like do not have IB exit juts above me, I would like the IB exists were separated between R and L channels, I would like the IB exists were not in the middle of the room but rather closer to walls and to be loaded to the walls. And there is another huge reason: above the ceiling in the attic I have a LOT of things going on. I that’s the exhaust pipes from bathroom fans, I have center HVAC in there, lightings, security and a few other systems are running in there and my carpenter spent a LOT of time to reposition the thing and to clear the space for two manifolds. So, we end up with 2 locations that are a good compromise to the are equidistant from my listening position and to be visually agreeable in the room (my listening position is not symmetrical in the room). So, it is not time aligned. I am planning to cross it at 20Hz and it will be indirect hitting my listening position, if we can call “indirect” about pressure wave propagation… 
 
So, in a way it is a compromise and “a bad design” to begin with but it is what it is. When I divorce my wife and built my next house explicitly for listening pleasure then I will factor the time alignment of IB into the room design but for now it will be as is. I wonder if I will be able to get from IB the overall quality of the sound I was able to get from the system with midbass horn. I know that IB and midbass horn are different animals but I am taking about the overall Sound….


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
09-07-2018 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,143
Joined on 10-12-2006

Post #: 21
Post ID: 25092
Reply to: 25091
Adjustments
My own limited experience with ULF has been that it hasn't been "directional" at all, and hard to say if "time alignment" is even a factor in most cases, apart from the inevitable delays caused by X/Os.  Also, where the speakers wound up has been based on overall sound "balance", if we can use that term for the sloppy curves over the bottom octave.  It will be educational to learn how Romy deals with the output added by the new ULF speakers interacting with that big room, especially since the speakers are in set positions.



Paul S
09-08-2018 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,534
Joined on 05-28-2004

Post #: 22
Post ID: 25093
Reply to: 25091
The IB project construction: done
OK, the driver in there, connected and my carpenter got his check. The project is over and I did not even go to the attic – very nice. Now I need to make it to sound right. It will be longer ceremony and probably will take a couple weeks. I did concert is as is and drove a SS amp throe it with no filtration, to assure that everything is in-phase and connected before I went the carpenter to go. The overall efficiency of this thing is super sensitive – it sound VERY loud. I cannot comment about sound yet as I did not use any filters or even phasing. However, there was one moment that I like as lot when I hear it – the location of the sound was very confused and very not cleared, and it is despite that I did not use any filters. That was exactly what I want from this channel - to be very clandestine and not detectable from my listening position. I am sure it will be much more as I put the filters and integration with Macondo into the game….

IB_Done.jpg



"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
09-11-2018 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,534
Joined on 05-28-2004

Post #: 23
Post ID: 25101
Reply to: 25093
The first IB testing.
I was sit today to do the calibration of my infinite baffle. I connected my 20Hz 4th order tube crossover with frond-end modified Yamaha B-2. The RTA  did show a very easy gain exactly where should be, the transition slope doe the magic. I rolled off approximately 18dB at the amp input to match the levels. I need to admit that adding even 10dB at the IB channels do not make it too much auditable. It took some times to do the phase verification: between the channels and between the main system and IB. Now everything looks like OK, the pink graph is with IB on.

IB_FirstTest.jpg

Sound. There is for sure the firmness, the very dense firmness at the bottom end. The proper things do crash properly-had now. Still, the overall sound is not what I need. There is no softness of the bottom end, in fact I feel that it got harder and more dehydrated. It feels like the main system and the ID runs in opposite phase but they of cause are summing, regardless what in phase polarity they are in fact in. I need to think why it does not sound properly. I might rye to soft the ID crossover and to go for 3 or even for the second order. It should give the softness… as I said I need to think about it.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
09-11-2018 Post does not mapped to Knowledge Tree
anthony
Posts 191
Joined on 08-18-2014

Post #: 24
Post ID: 25102
Reply to: 25101
Shake the house down
That is a lot of output at 6Hz.  I hope the Yammies have DC speaker protection because I'd hate a fault in the chain to unleash a heap of DC on those IB's...it may cause a a significant tremor at castle Romy.
09-11-2018 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,534
Joined on 05-28-2004

Post #: 25
Post ID: 25103
Reply to: 25102
There is nothing shaking.
There is nothing shaking in here. The roof structure and the things in the attic looks very stable, no foreign sounds. There is no pressure attack, something that I was afraid. I am a bit surprised how flat the ULF response I got. It might be the location if the IB hole turn to be lucky for my room… I think I need to make a sweep of IB with no crossover and to see how it goes…


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
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  »  New  Macondo’s lowest channel...  Good highs...  Horn-Loaded Speakers Forum     148  939193  09-15-2010
  »  New  Romy The Cat's new Listening Room..  Won't be the last time he makes that trip!...  Audio Discussions  Forum     478  1854383  03-28-2010
  »  New  Getting more power from SET vs. properly distorting SS...  Sound Board...  Audio Discussions  Forum     4  31893  05-09-2011
  »  New  How to get a LOT of SET power...  Not a refrigerator but......  Audio Discussions  Forum     101  573426  02-26-2006
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