Thanks for continuing to update! To be fair given that this is work in progress, that plot looks very smooth! Many people would be very happy to leave it right there! 4db down sub 30hz is pretty good. We start to drop 4db starting at 25hz.
Pure Low GR -- Infrasonic Panel
- Thread starter sbnx
- Start date
Okay, it is finally time to answer Ron's question.
I finished integrating both Pure Low at 30Hz this weekend. I say finished but in reality it does need a touch more height. I am currently using pieces of MDF to give them some height. I want to get some spike feet that are more adjustable. I think (know) that this is going to be much more critical when integrating them with the Trio at 125Hz.
In regard to oomph and physical impact of the Pure Low, I have not experienced anything that does what these do. The question I most often get is "Can they pressureize a room?". I think this is because people are skeptical that a panel can effectively pressurize. The Pure Low's get a 10 out of 10 in this regard. For physical impact I also give them a 10 out of 10. I will offer two songs as an example.
The first is Lydia Ainsworth's "Afterglow". I use this track all the time with subwoofers as it is very telling of how much sub 30Hz energy there is in the room. In the opening seconds you can hear and feel the low bass energy. It is very enveloping. There are several very low (20-30Hz) sustains that push. This song is full of this type of thing. By push I mean the bass energy physically pushes on me. The amount of "push" generated by the Pure Low is amazing. The Torus is a great subwoofer but it did not generate nearly this much envelopment and push.
The second is "Poem of Chinese Drum". I think most people have heard at least part of this one. The opening drum beats are very visceral. Ron experienced this when he heard my system. When setup properly the drum has a deep boom with a very quick and clear transient attack. This will punch the listener in the chest. This is just with the Spacehorns and is expected as the spacehorn plays flat down to 35Hz and the Drum is pitched at 40Hz. What the Pure Low's bring to the party is fullness to the drum. Now with each drum strike I can hear the full space of the drum. There is a foundational depth to the note that was not there with the spacehorn and was only hinted at with the Torus. It is like the energy of the drum goes through the drum and expands into the space. The experience is much more than visceral with the Pure Low. I had no idea that all of this was there before.
Ron often talks of the "acoustic center". He relates this to the point at which half the energy is above and half the energy is below. I think the idea is to relate this to how much "body" the music has. If the center is too high, the music sounds unrealistic because it is all about the upper midrange and treble. Inserting the Pure Low's definitely pulls the "acoustic center" downward. They have grounded the music. Whether I listen to vocalists or oboe the sound is much richer; much more full, much denser. The Torus did a decent job here, but just not to the same level. Actually, not really close. I have heard many people who kinda dismiss the bottom 2 octaves. Wait, how could they dismiss the bottom 2 octaves because doesn't that go up to 80Hz? No, I consider the first octave to be between 10 and 20Hz and the second octave to be between 20 and 40Hz. The argument is usally something like "Well, there just isn't much music below 40Hz". There is actually a great deal of content below 40Hz and even below 20Hz. I think people just have not experienced this in a convencing way.
What makes the Pure Low spectacular is that it gives all of the oomph, physical impact, envelopment, depth, richness and fullness without being bloated. Upright bass is still articulate. Timpani are still quick and clear. The Torus was able to do the same things but to much less extent. In thinking about the Funk vs. the Torus vs. the Pure Low. The Funk did a better job than the Torus on envelopment and oomph but it would just be in the way higher up. The Torus got out of the way more compared to the Funk and did provide some foundation and envelopment. The Pure Low gets out of the way and gives all of the fun subwoofer stuff in spades.
It is interesting that comparing the measurements of the Torus and the Pure Low the frequency response is ostensibly the same for both. Yet, the differences are stark in terms of sound quality.
@sbnx I am following your journey with these avidly, as these are very interesting subs. I'm curious about the room placement that you are using to bring this impactful presentation: how close to the back wall and side walls? How much elevation off of the floor?
Very, very interesting, Todd! Thank you for this very specific and detailed and insightful review!
The Pure Low seems to be a perfect solution for its mission!
Merry Christmas to you and Sally and the kids!
Hello @jbrrp1 ,
Regarding height. I believe that all subwoofers need much more height from the floor to sound their best. This has been the case with every subwoofer I have owned or setup. (And that is a sizable list) I currently have three pieces of MDF under each foot. One piece of 3/4", one piece of 1/2" and one pice of 1/4" so about 1.5" of added height in addition to the foot that comes on them. I have them raked back about 0.12 degrees.
I have the Pure Low is: About 22" from the side wall to the left inside corner. About 55" from the front wall to the right corner. I specify right/left as the Pure Low is wide and I have it toe-ed in to match the main speakers.
My main speakers are pulled out about 13.5' from the front wall so I have plenty of room behind them to play with. I am using the WIlson Active XO crossover. It only has an option of 12 or 18 dB/Oct crossover slope and it does not have EQ capability. So I used the position of the Pure Low in the room to find the best falling response. If I used a DSP or had a higher crossover slope then it would open up more positioning latitude. The position in your room would be different.
Based on Patrick's inputs, I believe Roy Gregory will be writing a review soon on the Pure Low GR. I know he positions them close to the wall. You can see them in many of the potos of the reviews he does. I also beleive that he will comment on the possiblities of putting them along the side wall which, IMHO, would work as long as the crossover poinnt is low (say less then 35Hz.)
~Todd
This has been an amazing read. Thank you. A few questions:
1. The Pure Low “can” be set up flush to a wall behind it? Unlike dipole panels, yes?
2. I checked and the air displacement of a Pure Low Large One panel (7 litres) is about the same as a good 15” cone sub. The surface area is greater but the excursion is 12 mm.
So I find it interesting that the physical all-out pure impact is so much greater.
3. I suspected the same as your observations about the Funk 18 you had heard and the Torus. Both attributes of clarity and space are important…my default would be to focus on space over clarity. So Funk.
That is why I continue to wonder how much more the Funk 18.2 does in clarity given that it is probably 3x the displacement of the single Funk 18 at apparently materially less distortion all the way up to 200hz and certainly 125hz which is the AG Trio main horn target.
More to learn!
1. The Pure Low “can” be set up flush to a wall behind it? Unlike dipole panels, yes?
2. I checked and the air displacement of a Pure Low Large One panel (7 litres) is about the same as a good 15” cone sub. The surface area is greater but the excursion is 12 mm.
So I find it interesting that the physical all-out pure impact is so much greater.
3. I suspected the same as your observations about the Funk 18 you had heard and the Torus. Both attributes of clarity and space are important…my default would be to focus on space over clarity. So Funk.
That is why I continue to wonder how much more the Funk 18.2 does in clarity given that it is probably 3x the displacement of the single Funk 18 at apparently materially less distortion all the way up to 200hz and certainly 125hz which is the AG Trio main horn target.
More to learn!
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Thanks for this detail! Sounds like they like to breathe, then, but perhaps can tolerate placement close to the wall. I'm curious about how much this is "not a dipole" with its back venting, and thus the implications on placement. I don't have quite the room you enjoy to work with, so this is a pretty important consideration.
Same here…there is a far corner where the Velodyne is…but fitting two of these for longer term dual subs would be tougher.
So if they can be flush to the wall and firing out then 2 can fit partly behind the main speakers flush to the front wall.
Let me address the against the wall idea. You can see a picture of Patrick's system a few posts earlier. He is mating the Pure Low with the Qual ESL. In that picture he does not have them too far from the wall. From the picture I would guess 15". In Roy's latest review of the Avantgarde Mezzo he has a photo showing the Pure Low in the background. From this picture they look like they are less than a foot from the wall. Both Patrick and Roy are pretty picky about their sound. So this suggests to me that the Pure Low can set these up pretty close to the wall. I have not personally tried it but it should be possible. Of course, if you are saying you need them flush to the wall with zero latitude for movement then I would say DSP is very likely needed.
Here is what Roy said in the HiFi+ review a few years ago. "That is where the PureLow LO breaks all the rules. Okay, so a frontal aspect that’s all of four-foot square definitely qualifies as big, but then it’s only four inches deep and you can use it a matter of six inches from the wall. More importantly, this is by far the easiest subwoofer I’ve ever had to position and adjust."
Here is what Roy said in the HiFi+ review a few years ago. "That is where the PureLow LO breaks all the rules. Okay, so a frontal aspect that’s all of four-foot square definitely qualifies as big, but then it’s only four inches deep and you can use it a matter of six inches from the wall. More importantly, this is by far the easiest subwoofer I’ve ever had to position and adjust."
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Hello Lloyd,
See my separate post on near wall setup.
In my mind, there are two things to consider. 1. the area that is pushing the air and 2. The front-to-back movement (displacement) of that area. The total volume of air is of course the area times the displacement. The max volume would be the area times the max displacement. But I contend that for music we never come close to the max displacement so to me it is irrelevant. For someone listening to movies at high volume levels where depth charges are being dropped on submarines then that might come into play. As long as the subwoofer has enough displacement that the driver can stay in the magnetic field and have low distortion at 110 - 115 dB music peaks I am good.
To me it is much more about the area of air that is being moved. That is why I prefer an 18" woofer over a 12" woofer. Or better yet 2 18" woofers. Each woofer has to move half as far so lower distortion and more surface area of air is being moved. Taken to the extreme this is what the Pure Low is all about. The surface area is that of about 5 18" woofers and the moving mass is insanely low. All I know is that I have listened to a few things where I fear for the structural integrity of my room.
The Funk subwoofers ar fine. They have very low group delay and the dual 18" will certainly move some air. If you are space constrained then get 4 of the dual 18's and you could stack 2 per side. It sounds stupid to do this, but it is not about how loud you can play the bass. it is about how much area of air is being pushed. (Just my opinion)
If you have not expermineted with height, try raising the height of the subwoofers and see what happens. Listen to some electric bass guitar, then add 3/4" MDF blocks under each foot and listen again.
Thanks, Todd! This has been extremely helpful. I have our one Velodyne DD18+ hiked up by around 7 inches due to 2 layers of isolation.
As for massive surface area and minimal excursion vs large surface area and large excursion…I think I will have to hear for myself to understand exactly what 2 Funk 18.2s can do…vs 2 Pure Lows. As you say, the massive amount of air displacement adds its own dynamic to sound that is not about chest thumping but more about foundational realism and sense of venue.
I remember reading that Dan D’Agostino had once used 6 of his dual-opposing 15” Krell Master Ref Subs with his Wilson X1/Grand SLAMMS. I imagine that was about pure effortless air displacement. So that opportunity (dual 18.2s) still intrigues me to understand what happens.
The interesting point you make is that if we are not utilising anywhere close to the capacity of dual 18.2s (and also not even close to the capacity of dual Pure Lows) then the default focus must then go to the extreme alacrity of the Pure Low panel where I could imagine it is nigh unbeatable.
But in the meantime, really enjoying your significant contributions all the way through this thread. Thank you.
As for massive surface area and minimal excursion vs large surface area and large excursion…I think I will have to hear for myself to understand exactly what 2 Funk 18.2s can do…vs 2 Pure Lows. As you say, the massive amount of air displacement adds its own dynamic to sound that is not about chest thumping but more about foundational realism and sense of venue.
I remember reading that Dan D’Agostino had once used 6 of his dual-opposing 15” Krell Master Ref Subs with his Wilson X1/Grand SLAMMS. I imagine that was about pure effortless air displacement. So that opportunity (dual 18.2s) still intrigues me to understand what happens.
The interesting point you make is that if we are not utilising anywhere close to the capacity of dual 18.2s (and also not even close to the capacity of dual Pure Lows) then the default focus must then go to the extreme alacrity of the Pure Low panel where I could imagine it is nigh unbeatable.
But in the meantime, really enjoying your significant contributions all the way through this thread. Thank you.
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Recorded with an iphone. You will have to listen with headphones with good bass. Even then they just can’t convey the power that is happening in the room.
Great! Will listen...is this only the main horns plus the PureLows with NO AG bass horn and NO 18" Torus?
Got it! Thank you. You have dedicated incredible energy to setting these up...and then done it again with the PureLows...Are you planning on eliminating the spacehorns to see if the Purelows can run the full gamut?
For me, and I suspect more than few others for whom the basshorns are just too much space (particularly if you still feel the need to have a separate sub to go below 30hz (i would)...going main AG horns plus single set of dual horns like the PureLows would be a magic combination if they worked.
Just listened to your clip…sounds phenomenal. Would have to go back to compare properly. From memory…the perceived space and separation in treble is better. Despite how hard hitting the bass is…and I know this track…your system positively IS massively hard hitting…I “remembered?” Your earlier recording being ever so slightly more? But truly ever so slightly.
Right after the words about “rain falling taking away the sun” in your other video I thought I recalled the metronomic beat being harder hitting than here but a smidgen.
While not subsonic, I wonder if (if my memory is even correct) the Torus or your setup was doing something down below that this beat was calling for…which is slightly different than how the PureLow is doing it?
I felt like this new version is more cleaned up, the other weightier but perhaps less clean?
But we are taking top single digit percentile performance for this track. 99% percentile either way! Enjoy and thanks for taking the recording…will go back to find the other one.
Right after the words about “rain falling taking away the sun” in your other video I thought I recalled the metronomic beat being harder hitting than here but a smidgen.
While not subsonic, I wonder if (if my memory is even correct) the Torus or your setup was doing something down below that this beat was calling for…which is slightly different than how the PureLow is doing it?
I felt like this new version is more cleaned up, the other weightier but perhaps less clean?
But we are taking top single digit percentile performance for this track. 99% percentile either way! Enjoy and thanks for taking the recording…will go back to find the other one.
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