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In Reply to: RE: Excellent posted by JBen on July 18, 2017 at 21:33:45
Heh.
I did only intermittent listening last night since I was working on moving the computer and installing some more smart lights. So I played a bit with speaker position and the diffusers and effected a pretty big improvement. Ordered some more cables, figured out what raceway to get at Home Depot, put P-Touch labels on my power supplies before they all get mixed up . . .
I got a little sit-stand desk and put the monitor and keyboard on it -- my head is that I can swing it around in front of the chair and do my computer work on it while listening to the speakers -- but as you can see, the setup is still jury-rigged -- I had to order a longer video cable and a roll-around stand for the computer and cables are draped all over. Work table to the left is going away once I fix the delam and the pink foam is for my experiments . . .
Today, I want to experiment some more with speaker and diffuser placement.
Not sure how this office arrangement is going to work out -- will having that big sit-stand desk next to me interfere with the sound? It didn't seem to yesterday.
Follow Ups:
Lunch break, snack bar and coffee in hand, I'd say you do have a bit of fun lined up for the days ahead.
Mmm, you know this but I'd remind you. There's upside potential still to be squeezed out by checking the "cable management" paths. Not just avoiding the power wallwarts and cables, but also anything extraneous to the audio signal which may carry power/signal. Cleaning up on this stuff will often bring out a thick layer of icing on the cake!
Now, if you don't mind, I'd like to play "Mary Has A Little Lamb:" or something on that baby grand you have back there. I haven't owned a piano in close to 20 years -- not that I really played much -- and that's probably the only thing my fingers may remember. Darn, got chocolate on them fingers, some other time then!
Have fun this evening.
I haven't even gotten to the point of worrying about that level of signal integrity! That, I tell myself, is for the refinement stage. Except that I do have dedicated power lines for the power amps. I should probably use one for the Mini DSP too, keep it away from the computers, smart lights, etc.
I actually have a hum problem here. It seems the cheapskate power company gave me 2 phases of 3 phase commercial power rather than 2 phases of 2 phase domestic power. So I only have 208V but worse than that, the two phases don't null so there are strong hum fields all over the place. I had to put ground lifters on the power amps and there's nothing practical I can do about it. (Well, I could run balanced lines but the buffer amps or transformers would do more harm to the signal than the ground lifters do.)
But the way I have things arranged I should be able to keep the audio runs physically separate from the power lines, video, and network cables.
Have to decide where the Mini DSP is going to live . . .
Yup, it is better left for a "final" round of tweaking...not that we really do "final" as such. :)
About the hum, there may be another angle. If you are using Cable TV, it can be the cause. There's a filter for it which I used until 2 years ago and worked like charm. Then, I switched to AT&T U-verse, which used Ethernet feeds, even to the DVR, instead of coax cable and did not need it.
Well, maybe I do need it now because I have a hum to deal with again. This may have been triggered by the AT&T tech who fixed an issue by swapping out Ethernet with coax to the DVR recently. Now I can't find the darn filter anywhere to see if it will fix the new hum, unlikely as it is.
If this is the cause of the hum issue in your case, it will unfortunately not be obvious or easy to pin down. It is sneaky as hell and merely having cable TV lines in the home may cause it. If you can disconnect the whole house from the cable feed, then you may be able to tell. I could not disconnect from the street feed and so I finally bought the filter: it worked.
I don't have cable myself, but there's still a cable connection the house on the exterior wall right below my listening room. I've not idea whether it's live or whether they disconnected it at the pole . . .
Meanwhile lots of experimenting today. First I noticed that the projected image was about spilling about half an inch over the border of the screen, so I used binoculars to get down to 1 pixel of overscan, which lets me move the speakers closer together without blocking the image.
Then I tried moving the right woofers forward and putting the panels in line:
I'd like to be able to do that because it makes the room more functional to have the MT panels pushed back and I was hoping that with the diffusers in place it wouldn't matter that the MT panels were only 3-1/2' from the front wall. Unfortunately, it did matter. It got very boomy -- to be expected with three panels against the wall in a small room like that -- but I could have equalized that out. Unfortunately, the image got squashed, so I pulled the speakers way out again, and now everything sounds great.
Receding blue lines are the limit of the speaker position without cutting off the image.
Only way I can think of pushing the MT's back would be some kind of reflector arrangement -- a reflection-free zone. I wonder if anyone has tried putting a reflector gobo behind the panels?
Josh, can you make a drawing showing your room? It looks very cramped. How far are you from the MT panels?
My Tympani IVa project is still resting but it will have the low bass driver very close to the side walls of man room, 411 cm wide (13.5 feet). As the driver will be mounted in a narow frame, the total width of the panel will be equal to the width of the two bass drivers. The line up I will try is low bass-tweeter-mid-mid bass for left side speaker and the opposite on the right side.
Looking at crossovers that let MTM's work I think you would have terrible lobing problems as the drivers are aligned horizontally as opposed to the common vertical arrangement. You are going to encounter problematic reflections and head in a vise issues despite the low crossover.
That said, it is not something I have tried (for the reaons given) and I am curious to learn how that worked.
Satie,
Do you refer to my post? As I will not use the original baffels/panels. The distance between the bass drivers in my planned configuration is 525 mm center-to-center. The original Tympani IVa have them separated by 460 mm. Besides, in my design the drivers can be placed in any position within the frame holding frame.
It is not an issue of offsets between the bass panels but how the horizontal MTM lobes vs. the MMT config when you time align and compensate for group delay. When you do it on the MTM the T portion needs to sit well behind the bass panels to maintain time coherence with 1st order or low Q high pass crossover. You can overcome that with high order crossovers but you lose midrange coherence in a big way.
My room is definitely cramped! About 14' wide and 13' deep, but L-shaped so partly 17' deep.
Here's a sketch, sorry it's so messy:
So basically the M-T panels are about 5' from the front wall and about 8' apart, and my chair is about 8' from the M-T panels. The mantle and the radiator interfere with the position of the woofer panels and I can't pull them further out in the room.
You'll likely get some lobing because you're separating the bass panels but if the low bass panel is against the wall you shouldn't lose bass extension. Ditto cutting down baffle width if they're against the wall.
Once possibility I've toyed with is putting the midbass panels next to the tweeter panels and then joining the deep bass panels together and putting those on one side of the room. That would cost me some extension on the flanking low bass panel though since there will be nothing on the side.
That's an interesting configuration. I didn't consider splitting up the bass panels in line.
I see you were having some proper fun this evening. Your challenges are interesting. A couple of fuzzy thoughts come to mind at well past 1am:
- Mart, or perhaps his bother Dan, used to have something exotic right behind the large Maggies, I think. The [tired] braincell wants to say these were egg crates?...anyway you can check.
- Try truncating the corners behind the Maggies. You are now adept at using the pink Foamular pieces, right? Unlike flimsy Styrofoam, they are firm enough to use for audio. I would try NOT to damp their reflective surface at first, just to see. (You can fill their [corner-facing] backs with as much damping as you may need.) While I know it works in many places, your room does have a nasty habit of throwing a curve ball...
Of course, you can get rid of the projector and simply do music right. I will kindly store the gizmo here for you :)
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