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In Reply to: RE: Another First Reflection Trap (FRT) Adventure : Quasi-Ambiophonics posted by JBen on October 05, 2013 at 23:42:43
@JBen (and OldGuy42):"Old Guy 42 and I are jointly evaluating a few related tweaks that should lend themselves for some cheap and fun approaches. To be sure, the use of those circular pipe edges brings some advantages, which is part of what Old Guy 42 and I have been exploring. However, those who try them may wish to fine tune their respective results. For this, they may need to add hard edges to avoid top-end clarity and dynamic impact loses.
For example, my MMGs have had Armaflex butyl (2" tape) along the front of the frame and rounding it around the frame edges for years. Yet, I have not found a way to leave the outer edges exposed; always need to add a hard edge like the factory trim.
Yet, in your setup, it appears that the soft butyl pipe insulation edge doesn't do this? If so, it could be a function of your whole setup as a system, which would be very interesting!"
Short answer: yeah, it's a total system thing going on here.
Longer answer: I'm only using the pipe insulation in 2 places - where the FRT leans up against the speaker, and on the rear edge of the FRT closest to the front wall. In both cases, these do not have any direct effects on the primary sound. In fact, the FRT is positioned such that any sounds which might be affected by the pipe insulation between it and the MMG are delayed from reaching the listening position (LP) for a LONG time, acoustically speaking; ditto the rear FRT edge insulation. In fact, the only reason to use pipe insulation between the MMG and FRT is to dampen vibrations and keep the panel from buzzing along to those wonderful bass notes. ;-)
Just in case I wasn't clear about the point of this mod, it is to get the most out of Maggies (and possibly other planars) in a small, square room - the kind of room that wise Planar enthusiasts would insist they would not work in, for all kinds of technically sound reasons. Well, I'm an engineer, and I make a living tricking Mother Nature into doing things (while following Her rules) that give results which would not normally be possible. People cannot walk on air, but build a bridge and effectively you're doing that as you cross a river valley, for instance. Acoustical engineering is not my specialty, but I realized that the laws of reflection and incidence apply for higher frequency sounds - the ones most critical for localizing phenomena in space. Hence the FRT concept.
My trickery in this case is 2-fold: 1) use panels angled such the early reflections of mid-to-high frequencies from front and side walls are delayed to be greater than 10 milliseconds from the initial signal, and 2) to use the forward part of the FRT panel closest to the LP to address what Floyd Toole himself called "An Important One Toothed Comb - A Fundamental Flaw in Stereo". When I came up with that idea, tested it, AND FOUND IT WORKED, I was excited. Still am.
BTW, I'm with you that the forward edge of the FRT mist not have any Armaflex on it, partly for the reasons you cite.
BTW, in the credit-where-credit-is-due department, thank you JBen for introducing me via an earlier post to Armaflex. It really is versatile stuff.
MG-bert
Edits: 10/06/13Follow Ups:
MG-bert, I know the challenge that you are so creatively tackling. It can't be easy, if I judge by a little on-the-fly experiment I did.Last year my neighbor had to rebuild a long wall that became water damaged. A load of drywall was brought in for the project. However, the contractor was delayed; hospitalized for a few days after an accident. So, I asked my neighbor to loan me a few pieces of the drywall for a day.
With it, I "shortened" my room from 12x25 or so to 12x12. It was an audio disaster compared to its usual sound. I suppose that I could have fixed some of the things that changed so radically. In fact, had I had more time I would have applied some of the lessons you had already shared, for I remembered your earlier posts on the subject.
With this in mind I was about to ask my neighbor for an extra day. Just then my wife, who had gone to visit her mother, called. She decided to return earlier than planned.
That was the end of the experiment right there. LOL! Had she walked in while the mess I made was still on...I would have joined my neighbor's contractor in the hospital.
Edits: 10/07/13
@JBen:
"MG-bert, I know the challenge that you are so creatively tackling. It can't be easy, if I judge by a little on-the-fly experiment I did.
Last year my neighbor had to rebuild a long wall that became water damaged. A load of drywall was brought in for the project. However, the contractor was delayed; hospitalized for a few days after an accident. So, I asked my neighbor to loan me a few pieces of the drywall for a day.
With it, I "shortened" my room from 12x25 or so to 12x12. It was an audio disaster compared to its usual sound. I suppose that I could have fixed some of the things that changed so radically. In fact, had I had more time I would have applied some of the lessons you had already shared, for I remembered your earlier posts on the subject.
With this in mind I was about to ask my neighbor for an extra day. Just then my wife, who had gone to visit her mother, called. She decided to return earlier than planned.
That was the end of the experiment right there. LOL! Had she walked in while the mess I made was still on...I would have joined my neighbor's contractor in the hospital. "
LOL! That's why in my castle, the rig lives in it's own outbuilding... er, shed. My better half never goes there, and since it's a shed, the pressure is off to neaten up either during or after an experiment. Besides, that way I don't have to introduce the Maggies to our cats...
And wow! A full 12' X 12'! At least 20 square feet bigger than my space. Can't imagine what you did with all that extra room! Oh wait, you have the truncated corners, don't you? That would complicate a nearfield setup a bit.
Anyway, thanks for the kind words about creativity. We just rewatched the "Dinner with Schmucks" movie; am I a candidate? ;-)
I apologize if I already posted the link below, but a while ago I had the good fortune of having a pair of Maggie-owning audiophiles who regularly post on the Planar Circle come out to the wilds of Western Maryland to visit the shed. Although this was before I came up with the present FRT configuration, they did hear my so-called mini-FRT setup. Spoiler alert: they seemed to be impressed, and I am proud of what got pulled off in my tiny space. Maybe you can compare what you heard in your room to their take?
MG-bert
MG-bert, I read the whole thing a couple of times trying to relate to what I heard here when I "reduced the room". Other than being glad that your system performs so well, I am not sure I got enough details to compare to your un-EQ'd config. I do remember what went wrong vs my normal room config, though.
Here is what I remember. Please keep in mind that I use no equalizer or DSP. The nearest thing to it is the ability to raise & lower the tweeter at the PLLXO biamp interface (and this did not help me at all). In addition, I tuned the 1st/2nd order PLLXO points IN THE NORMAL ROOM...which is EQ of sorts.
1. Ordinarily, I have to tame bass somewhere in the 65-80 hz range in this room because the speaker on the right side sees a solid concrete wall. I have acoustic ways to do this. However, the square room overwhelemed my normal measures. The normally strong but acceptable peak now zoomed to offensive boominess.
2. After much work, I have the 100-250hz range real good, full and texture-rich. Well, the square room ALSO ruined this. However, since I could not measure that day, all I can say is that trombones, tubas, cellos and other instruments lost their proper heft, texture & presence. EXCEPT as they went higher up into the upper-bass/low-mids range. Somewhere there, a peak must have risen...quite strong and annoying.
3. In those days my system had already acquired most of its current slammy dynamics that can actually hit you perceivably and shake the sofa cushions at times. This went out the window. The forward impulse got lost.
4. The lower bass 40-60hz went AWOL...probably drowned by the peaks higher up. I don't use the subwoofer for music but suddenly I felt like it was needed badly. I turned it on just to see but turned it off right away...too messy & muddy at the setting it normally has.
5. Overall soundstage and soundfield, which normally enlarges the room and "erases the walls" was severely hampered, though not wiped out. I have heard some Maggies do worse when in over-damped rooms.
6. Imaging within the soundstage lost its compelling ability to "be looked at". Normally, it is not just solidity. One can also turn the head and look from side to side and the 3D elements stay put. Not so with the experimental 12x12 "room". To be fair, I've heard far worse from my own system in the very early days...and some friends thought it was great in those days...go figure!
7. The upper midrange and top-end did not suffer severly as far as "peakiness". I was not impressed by them but it may have been that I was a bit too fixated on what happened elsewhere in the lower range SQ.
8. The upper midrange and top-end did not lose much clarity either, I felt that it would have been easy to "re-tune" for the "room change".
9. The center imaging remained surprisingly solid, though much shallower.
My neighbor made a comment that stuck in my mind for being very true. He said that the speakers sounded much smaller.
So, you see. In reading about what you have accomplished so far in an even smaller space I can appreciate the effort it took. I think folks should take a look at your approach and adapt what may be needed for their places. I certainly would.
@JBen:
Sorry for taking so long to respond. Remind me never to ask you to do something - you'll spend hours and hours doing it! ;-) I really appreciate your feedback here, if for no other reason that it does validate the fact that making Maggies "sing" in a small, boxy room is a non-trivial exercise.
That said, I would dearly love to hear your setup someday. I still have not been able to achieve the really 3D pinpoint imaging you describe. Earlier, you gave us a guided tour through the first minute of the Eagles "Hotel California" from "Hell Freezes Over", and while I get pretty good depth, I don't get the whistle coming from the balcony over my head at one point like you described. On the other hand, I do get the occasional sense of instruments in front of the plane of the speakers, and since those are about 5 feet away, that is CLOSE! Also, I can localize the relative height of instruments.
One track which seems to be out of print now by a little known band called Mostly Autumn ("Shindig" from "Spirit of Autumn Past") has a jaunty synthesizer bass beat coming from my feet! Literally goes from left foot to right foot and back and forth. Then a fiddle comes in, a little above ear height and behind the plane of the speakers on the right, then a flute on the left forward of the speaker plane... you get the message. Lots of fun.
MG-bert
LOL! I do take my time testing some stuff. BTW, I did run "Hotel California" during that square room test. It was nothing like I am used to. It does remind me that, at the time, I though that perhaps I could have applied heavy damping to the "new wall" behind my seat. I have learned to respect what happens in the space behind my seat, for it helps those recordings that capture ambience and fuller soundfield. It also seems to help with dynamics a little. Come this Christmas, I know that the Christmas tree will bring a little more than a shade for the usual presents. It always helps overall SQ.
Incidentally, "Hotel California" was also at work last evening. I had just returned from a trip. Before leaving, I had begun to test a tweak that Old Guy 42 had encouraged me strongly to try. Initially, last week, it seemed really good. However, it takes a few rounds of something before I am convinced that I am not having "audio fantasies".
So, I ran a few hours of music after my trip (and a nap to recover). It was all good. The tweak may further allow me to enjoy most of the best that my system can only -- until now -- do during the coolest months in South Florida. These are the days when lower temps allow many folks to turn off their A/Cs...so there is less ambient & powerline noise. The tweak also seems to help my system at the worst of it all. I have a park close by. On evenings when they turn the many large floodlights on...I can tell without looking.
It will not help everyone but the tweak is simple and has been known for a while. I'll let OG42 tell about it, for I encouraging him to do so, and I've gotta run to help a friend with his system now.
@JBen:
You said:
"LOL! I do take my time testing some stuff. BTW, I did run "Hotel California" during that square room test. It was nothing like I am used to. It does remind me that, at the time, I though that perhaps I could have applied heavy damping to the "new wall" behind my seat. I have learned to respect what happens in the space behind my seat, for it helps those recordings that capture ambience and fuller soundfield. It also seems to help with dynamics a little. Come this Christmas, I know that the Christmas tree will bring a little more than a shade for the usual presents. It always helps overall SQ."
In the FWIW department, I have tried putting absorption on the wall behind the listening seat, and I have to rip it away. There is a huge difference between delayed reflections coming from behind and NO reflections coming from behind. Sounds totally unnatural. And, it's my theory that human evolution has conditioned our hearing to be able to deal with early reflections (less than 10 milliseconds from the initial impulse) coming from behind differently than those coming from the front or side. Think of seeing an acoustic guitarist in a fairly small club, and you sit along the rear wall. You'd just be aware that you're in the back, but the impact on sonics should be minimal.
Having said that, I would kill for a larger space to set up my MMGs, because I believe you when you say that the space behind you allows for a rich tapestry of later reflections to help solidify the reality of the performers in the room.
FRTs do help in my box, though!
And OldGuy42, what's your great idea? I'm all ears!
MG-bert
That, my friend, is a great thing to do and should serve you well. We all fail to "unplug them" enough from time to time and thus fail to tap some opportunities.OG42 and I are exchanging tweaks -- new and old -- these days; dusting off some known ones and even inventing others. By using some similar music to correlate observations we can better tell what's promising to share.
In any event, it serves me well, I have to say. There are a few tweaks out there that we all may have seen with interest but not really tried, for any number of reasons. Well, OG42 brought this simple one to the foreground and insisted that I try it. I am very glad that I did.
While "YMMV" does apply, it is so easy to try that it should be worth doing so. Cheap that I am, grabbed some bags of Radio Shack item #274-321 and shorted the plugs with a drop of solder...it worked like charm.
[As warned before by others: DO NOT SHORT RCA OUTPUTS ]
Edits: 10/14/13
Hey MG;
MG wrote..."And old guy 42, what's your great idea?"
This is definitely NOT my idea. I'm a no-tech old man that loves music.
I found this "idea" in the Tweaker's Asylum. (see link) The RCA shorting plugs are for analog INPUTS ONLY, as Jon's post states. I also used a 75 Ohm "terminating" RCA plug on the SPDIF output of my CDP, again, according to Jon. The "shorting RCA plugs" replaced the Cardas caps I have used since 2005.
A very nice improvement in imaging and detail on my old stuff. But, as you know, with these things, YMMV.
Also, again, a nice job with your FRTs!! If I have the good fortune to fall into a dedicated room, I will try your ideas, for sure.
Again, do NOT use a shorting RCA plug on an analog OUTPUT!!!
Take care....old guy
Interesting. Reminds me of the Jecklin disk.
http://en.wikipedia.org/wiki/Jecklin_Disk
The main difference being that the above is made out of a soft, absorbent material, while your FRTs are solid and reflective.
Have you thought of or tried using a soft, absorbent material?
@DreamOperator:
The point of the panels isn't to absorb sound - it's to deflect reflections so the time they take to reach the LP is greater than 10 milliseconds - actually it's longer for a lot of these. That way, the essential character of planars is maintained, vice turning them into a very large pair of mini-monitors.
MG-bert
I see what you're saying. I'd like to try this sometime.
@DreamOperator:
Go for it! It's a real cheap experiment, and it really cleans up already good sonics!
MG-bert
I have some 4'x2'x4" fiberglass panels with solid wood on one side.
I took a pair of them and placed them as to block the left tweeter from the right ear and vice versa. Wood side facing the closest speaker.
While the rear reflections were not altered and there was a ton of absorption going on in the middle, I was able to get some sense of the effect. Lots and lots of depth and very clean separation.
Perhaps I'll play around more down the road. Thanks for sharing.
@DreamOperator:
De Nada; I see posting here as a way of publishing findings, with the hope of getting them "peer reviewed". So thanks for filling in that part.
I just realized there might be a far less intrusive way of accomplishing the "ambio" trick. Need to make another trip to the hardware store, which might only happen in the next week or so... Would be great to increase the WAF factor from the imaginary number the current FRT configuration currently has!
MG-bert
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