couldn't resist posting another pic....Almost done...I'll have a test by tomorrow morning at the latest!
CR Treatment and Tuning---The home stretch!!
Originally posted at johnlsayers.com, topic 21368.
Thanks Brother !!!
Hi, I got the sheet of off of ebay. If you look up perforated sheet metal, you should get results. Pretty sure that's what I did. Mine is aluminum which I recommend for weight and ease of cutting. To be clear, The covers on the back are standard rack vents. I only did the sheet on the desk top. Here is the link to the one I bought: https://www.ebay.com/itm/Perforated-Met ... 2749.l2649 Your desk is insane compared to mine!! :lol: In case your interested in the vented rack blanks, I got them here: https://www.pennelcomonline.com/
OK...The desk is in the room but things are still rough. Stuart, I tried building some little shelves for the feet but the screen is way too close. The screen is going to have to go back close to the window or Its going to be too claustrophobic..
I'll have some tests probably by late tonight or tomorrow morning. As usual. the final details have bogged me down and pushed me back a bit. still got plenty of finish work to do.. All in all, not bad on progress though...
Looking very neat, Frank! And great workmanship, too (As if I expected anything less... :) )
I'd suggest getting a proper articulated mounting arm for the screen, so you can keep it as low as possible, without those legs on it, such that it doesn't block too much of the view through the window. The arm bolts to the back of the screen. It's a standard fitting.I tried building some little shelves for the feet but the screen is way too close. ... The screen is going to have to go back close to the window or Its going to be too claustrophobic..
Cool! I really wanna see that data! - Stuart -I'll have some tests probably by late tonight or tomorrow morning.
Cool....I'll look into that.
I'll do a quick REW. I had to tweak the subs and still need to do more. Things changed of course. I'll have something in about 30 minutes. Mind you, it won't be the final sub arrangement.
Think I found a perfect solution while i was typing this:
https://versadesk.com/universal-single- ... _BwE#tab-2
I can punch a hole through the shelf and mount that!
Sent!!!
jumped too soon on that one...It only goes up to 27" :(
Also, Sorry about the naming. I got too excited...That's just a 3 set with subs and mains together.... :oops:
The REW data is looking really nice, actually. Better than I had hoped. There's a couple of issues we should try to track down and see if they are fixable, but overall it's doing rather well! I'll see if I have a chance to post some updated REW graphs later.
- Stuart -
:thu:
Struggling with the subs again, but I suppose we can live with what we got...
A better pic for all you desk porn fanatics! Still got some touch up work, but its getting there...
I'd really, really, really, REALLY suggest that you give it another go with the KH805 under the window!, sideways... 8) :D It will fit... Start out with JUST that one on, fairly low level, then set up the two Tannoys, one on each side of the desk, near the sliding glass doors, and phase invert just ONE of those. This is a fairly simple concept: you are attempting to set up a planar wave running across the room with those two, where one speaker creates the wave and the other speaker cancels it, with the KH805 filling in the middle. It's the simplest form of a bass array. Minimalist version. And don't apply any EQ! Just the subs. We are ready to start with the digital tuning now, so any EQ you apply is only going to mess that up.... You don't need to get things perfect with the subs: the digital tuning will take care of that. The real purpose of the subs right now is to fill in the SBIR dips and other dips as well as possible, and smooth out the phase response. As long as you can get that in place, then we can move on to digital tuning. The KH805 will REALLY get us down into the low end, which the Tannoys are not doing... - Stuart -:thu: Struggling with the subs again, but I suppose we can live with what we got...
oh alright... :roll:
Thing is a tank! Curse you and your obnoxiously large sub suggestion!!! :P
:lol: :lol: :lol:
Think of it this way: It will knock your socks off! And thus it will keep your toes warm in winter, and massage your feet too, if you turn up the volume to 11! :)
But I do agree: It's a monster! However, it will really push the low end down to where I'd like to see it in that room. Your room deserves it, I think! It's looking so good already, that it really should have the low end extension that impresses the hell out of musicians and producers. I aim to get it as close to perfection as we can. ... You DID say you wanted this to be an amazing studio, right? :)
- Stuart -
hmmmm....feels more like this :horse: , but I trust you...It comes from hours of pushing these subs around the room and driving myself crazy.
In all honesty I don't expect much because the dynaudio is performing about the same. I'l do a measurement as proof of course.
:thu: Start with JUST the KH805... experiment with phase and cross-over, to get it reasonable. Keep the others off, and send me a REW test like that.
Then set up JUST the Tannoys on opposite walls, one phase-inverted (it doesn't matter which one), and send me a test like that (KH805 turned off).
That will give me enough to start on the digital tuning, while you play around with the exact placement, to see if you can improve things more..
Fun and games! Playing chess with subs is an entertaining occupation! (not)
- Stuart -
OK!! the Neumann wins damn you!! :mrgreen:
Also,
I'd like to hang this picture above the CR window if we're not going to put anything up there...
:yahoo: :!: I just saw the new REW data for the sub tests you did... and I have to admit that you are right: The Neumann DOES win :) 8) 8) 8) (I really hate to say "I told you so, but, ....") OK, but that latest REW data you sent only goes up to 600 Hz, so please do a full spectrum test now (without EQ!), and send me that. 3 tests: LS, RS, LRS. Then I'll post some images of REW data here, so you have some bragging rights.... (I reckon you've earned it!). And please check your calibration levels too: the last few tests seem to be about 5.5 dB higher than normal. And sure, go ahead and hang the painting as well, if you want. That area above the window can stay bare. I don't think there's anything we need to do up there at this stage. (Hopefully the canvas doesn't decide to act as a resonant membrane...) Next up: Do you feel like chasing down that 1ms refection that I mentioned? You'll need some string, a tape measure, and some masking tape.... - Stuart -OK!! the Neumann wins damn you!! :mrgreen:
I'll get those tests up in just a bit.. Gotta get the dynaudio shipped back real quick. Guess that's not gonna work out!
The calibration has been weird. I've had to re calibrate a couple times lately and it still seems to be off...hmmmm.And please check your calibration levels too: the last few tests seem to be about 5.5 dB higher than normal.
Sure, I'll need instructions..Next up: Do you feel like chasing down that 1ms refection that I mentioned? You'll need some string, a tape measure, and some masking tape....
Unless you want to keep it for your rig in the Live Room? Or do you have another sub in there? I'll get back to you with the instructions for the "string trick" in a few minutes. - Stuart -I'll get those tests up in just a bit.. Gotta get the dynaudio shipped back real quick. Guess that's not gonna work out!
One more thing: You can start running your REW tests from 10 Hz upwards now, instead of starting at 18, as you have been doing up to now. That KH805 goes down really low, so I'd like to make it sing and roar, to check that there's nothing happening in the sub-sonic area. I'll roll that off in the digital tuning, of course, but we do need to know that the room isn't trying to sing whale-songs, now that you unleashed the 805 in all it's glory.
- Stuart -
:thu:
No, I love Neumann in the LR so I'm going to swap it out... :mrgreen: That sub is annoyingly large and amazingly awesome!!
Off to UPS..back in a flash!
:lol: :roll: :horse:
OK, instructions for the "string trick"...
Carefully measure the distance from the very tip of your measurement mic to the acoustic center of your LEFT speaker (both speakers show the same reflection, but let's work with the left one, to identify the cause, as the peak is a bit better defined on the left). The location of the acoustic axis is shown in the SketchUp model. Now add 33cm to that measurement (or 13" if you live way back in a different century... :) ). Get a piece of string that is as long as that measurement, plus a few extra inches on each end, so you can attach it. Mark that exact length on the string with a Sharpie or some such. Tape one end to the front of the speaker so the mark is on the acoustic center, and tape the other end to the measurement mic, so the other mark is at the tip of the mic. The 33cm slack will hang down in the middle.
That loop of slack string represents the EXTRA flight time of the reflection: it is taking that much longer than the direct sound in time (and therefore distance) to bounce off "something" and arrive at your mic almost 1ms later than the direct sound. Now gently move the "slack" around the room to find the hard surface that it touches. There should be only one surface that you can reach perfectly with the loop of slack, but you might find that there are several points on that surface where the loop can reach: That's fine. Look for the spot where the angle that the string makes with the "surface" seems to be the same on both sides. In other words, "angle of reflection = angle of incidence". That's the center of the area that is causing the specular reflection.
My guess is somewhere in this area:
Repeat for the RIGHT speaker, with the same string.
To double check that we have found the issue, put a dinner place-mat sized piece of insulation (the thin stuff that you used for inside the slot walls) over that area on both sides, and do a REW test like that. That won't be the treatment! It's just to confirm that we have found the right spot.
Then, if you feel like playing with string some more, you could go hunting for a couple more reflections...
On the left speaker, you'll need to mark bits of string at "direct mic-speaker distance plus 41cm", direct + 132cm, and direct+167 cm. For the right speaker: direct+41cm and direct+134 cm. The shorter distances might be other parts of the desk, but the longer distances are probably either floor bounce, side wall bounce, or maybe a bounce off the cloud. Those are all lower level than the 1ms issue, but still very worth treating if you can find them. They are all within the critical 20ms/-20db Haas window.... and they are also the very last major issues in your room! If we can subdue those, then we'll do the digital tuning... and move on to the live room tweaks!
- Stuart -
Yay!!! :yahoo: more tedium!!! :-x oh well....
On the up side. I have a new beak through discovery! The Neumann stands on its own! I ended up losing the Tannoys and we have an easier situation. It Eq's with much fewer bands and has that awesome Neumann sound...Tweak, tweak, tweak!!!
file sent!!
Quick thought, We do have the option to tilt the top a smidge if your interested....
To elaborate on the Neumann... Not sure how I missed putting it more out in the room like I have it now....slightly under the desk instead of under the window..I'm Relieved to be out of the 3 sub situation. It sounds better all around. More clarity straight up...Well, largely because its the Neumann too.
Sure! It's worth a try. With the short distances here it will need a fair angle on it, so try to tilt it as much as you feel comfortable with, and we'll see if that makes a worthwhile difference. Not so much that your coffee mug slides off! - Stuart -Quick thought, We do have the option to tilt the top a smidge if your interested....