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Post by marcl on Aug 11, 2024 8:04:08 GMT -5
I must disagree! With all due respect! 'if it doesn't work I just revert to Plan A'.........This is a fine time to innovate or simply experiment....... When I installed my Maggies? Simple pair and later a sub......But ME? I couldnt' follow the directions so I tried them ALL FOUR ways. Pole piece forward or back? Tweeter 'in' or 'out'......  So? IMO, 'revert' to Plan A is a non-starter. In my speaker foolings and without any measurements? Installed an artsy absorber on the side opposite. Reflection tames. Than the orientation experiments. The only thing not messed with was speaker to amp connections... As it turned out? Some setups last only minutes. Others last for hours or even days. When I got to my final tests, I ended up by doing a fine tune and leaving it......Little bits of toe? Wall spacing to desired included angle? I'll bet you get on to something. Maybe unexpected or without warning from any of the people who know this approach and may have known? I have a few ideas, but based on maybe......philosophy? So we can maybe talk later...... cheers..... Whoa, hold your horses Leo... back up!  In my last couple posts with the schematic I described how I'm replacing my two Outlaw subs with two Open Baffle Dipole subs. I changed the configuration to use a mixer to mix sub signals rather than a miniDSP. But also, I came up with a way to simplify my CENTER channel configuration, changing the way I play it <200Hz. That is shown in Plan A which is functionally the same as my current configuration but simpler. Plan B is a different way to play the Center <200Hz. Instead of just sending it to the L/R DWMs, I'll send it to the L/R 3.7+DWM. If Plan B doesn't work, then I know Plan A WILL work because functionally it's the same as what I'm doing now. Nothing has changed with my 3.7/DWM setup ... still in the Rooze config pointing 45 degrees to the wall. |
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Post by marcl on Aug 11, 2024 14:28:33 GMT -5
So while waiting for the sub cabinets to be finished, and for some final components to arrive, I was sitting in my "padded cell" .... inside the box - and nearly asleep listening to some Atmos music - thinking outside the box. I came up with an alternate connection scheme using exactly the same components as my original plan, but arranged differently. Here's my original Plan View AttachmentAnd here is the new Plan B View AttachmentSo what is different? - In Plan A the Center channel is Small. It goes through a crossover that sends >200Hz to the CCR and <200Hz to the two DWM panels. I then cross it to Bass Management around 60Hz.
- In Plan B the Center channel is Large. It goes through a crossover that sends >200Hz to the CCR. <200Hz goes to a mixer that combines the Lo Center output with the L/R Front outputs. The combined L/R + C Lo then go to the active crossover which sends <50Hz to the subs. L/R +C >50Hz (C only 50-200) are split to the 3.7 and DWM L/R fronts.
- As before, the L/R Lo outputs of the crossover combine with the Center Sub LFE output and go to the subs. I have the option to run these signals mono to both subs, or to send L/R to their respective subs and LFE to both.
Why might Plan B be better? Because everything below 200Hz for the Center channel goes to the L/R 3.7/DWM speakers. This, as opposed the Center 50-200Hz going only to the L/R DWMs. I think the imaging and quality of the sound for the Center below 200Hz will be enhanced, and will have the benefit of higher power from the L/R 3.7 + DWM amplifiers.
I'll think about it some more, but I think it will be better!
p.s. ttocs ... keep me honest ... I think there will be a problem after I run Dirac  Okay ... Plan B is a success so far! Response with no Dirac is very good and LCR channels match very closely. Low end distortion in the Center channel seems to be lower. Even using the old Dirac calibration gives pretty good results. LCR ... Blue, Green, Pink ... No Dirac or PEQ ... all set to Large ... subs play below 50Hz. (Note that I do not yet have the OB Dipole subs installed. Subs in this measurement are my Outlaw subs run through a miniDSP instead of the mixer shown.)   |
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ttocs
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I always have a wonderful time, wherever I am, whomever I'm with. (Elwood P Dowd)
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Post by ttocs on Aug 11, 2024 14:49:53 GMT -5
So while waiting for the sub cabinets to be finished, and for some final components to arrive, I was sitting in my "padded cell" .... inside the box - and nearly asleep listening to some Atmos music - thinking outside the box. I came up with an alternate connection scheme using exactly the same components as my original plan, but arranged differently. Here's my original Plan View AttachmentAnd here is the new Plan B View AttachmentSo what is different? - In Plan A the Center channel is Small. It goes through a crossover that sends >200Hz to the CCR and <200Hz to the two DWM panels. I then cross it to Bass Management around 60Hz.
- In Plan B the Center channel is Large. It goes through a crossover that sends >200Hz to the CCR. <200Hz goes to a mixer that combines the Lo Center output with the L/R Front outputs. The combined L/R + C Lo then go to the active crossover which sends <50Hz to the subs. L/R +C >50Hz (C only 50-200) are split to the 3.7 and DWM L/R fronts.
- As before, the L/R Lo outputs of the crossover combine with the Center Sub LFE output and go to the subs. I have the option to run these signals mono to both subs, or to send L/R to their respective subs and LFE to both.
Why might Plan B be better? Because everything below 200Hz for the Center channel goes to the L/R 3.7/DWM speakers. This, as opposed the Center 50-200Hz going only to the L/R DWMs. I think the imaging and quality of the sound for the Center below 200Hz will be enhanced, and will have the benefit of higher power from the L/R 3.7 + DWM amplifiers.
I'll think about it some more, but I think it will be better!
p.s. ttocs ... keep me honest ... I think there will be a problem after I run Dirac Okay ... Plan B is a success so far! Response with no Dirac is very good and LCR channels match very closely. Low end distortion in the Center channel seems to be lower. Even using the old Dirac calibration gives pretty good results. LCR ... Blue, Green, Pink ... No Dirac or PEQ ... all set to Large ... subs play below 50Hz. (Note that I do not yet have the OB Dipole subs installed. Subs in this measurement are my Outlaw subs run through a miniDSP instead of the mixer shown.) View AttachmentView AttachmentLooking good Billy Ray! Which level controls are available for the Center Channel? I know you’ve got the processor for overall level, and the subs have their own level control, but is there also a level control for 50-200Hz? |
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Post by marcl on Aug 11, 2024 15:30:26 GMT -5
Okay ... Plan B is a success so far! Response with no Dirac is very good and LCR channels match very closely. Low end distortion in the Center channel seems to be lower. Even using the old Dirac calibration gives pretty good results. LCR ... Blue, Green, Pink ... No Dirac or PEQ ... all set to Large ... subs play below 50Hz. (Note that I do not yet have the OB Dipole subs installed. Subs in this measurement are my Outlaw subs run through a miniDSP instead of the mixer shown.) View AttachmentView AttachmentLooking good Billy Ray! Which level controls are available for the Center Channel? I know you’ve got the processor for overall level, and the subs have their own level control, but is there also a level control for 50-200Hz? There are level trims in the crossover for the Center LPF and HPF. I also have control of the Center LPF in the mixer. The Center goes to the XKitz crossover and comes out >200Hz and <200Hz. >200Hz goes directly to the CCR amp. And the <200Hz is full range down to whatever because now the Center is set to Large and that is played by the 3.7/DWM of both L/R and the subs below 50. For the tests today, when the Center LPF was a little too hot I lowered it at the mixer. I think that was okay ... and easier than having to unscrew the lid on the crossover to get to the trim pot. When I do a new Dirac tomorrow I'll see how the measurements look and I may decide to tweak some things a bit. It's so close now though I don't foresee any problems. |
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Post by marcl on Aug 29, 2024 13:04:04 GMT -5
STILL waiting for the cabinets to be done, but this week I made progress ordering lots of little stuff to finish the build including some tools as well as parts. So the plate amps want to be in a box, and since they CAME in a box, I figured what better box to be in than the box they came in ... + some trimming, ExoHyde, rubber edging, grommets and sleeve for the cables. I did solder the Speakon connections because it just seemed to be the right thing to do. They will go RIGHT behind the subs so the cables stay short, and they'll be pretty much out of sight.  |
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ttocs
Global Moderator
I always have a wonderful time, wherever I am, whomever I'm with. (Elwood P Dowd)
Posts: 8,168
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Post by ttocs on Aug 29, 2024 13:32:50 GMT -5
STILL waiting for the cabinets to be done, but this week I made progress ordering lots of little stuff to finish the build including some tools as well as parts. So the plate amps want to be in a box, and since they CAME in a box, I figured what better box to be in than the box they came in ... + some trimming, ExoHyde, rubber edging, grommets and sleeve for the cables. I did solder the Speakon connections because it just seemed to be the right thing to do. They will go RIGHT behind the subs so the cables stay short, and they'll be pretty much out of sight. You clever guy you! Now I see what that U-shaped material is for. |
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Post by fbczar on Aug 29, 2024 13:37:01 GMT -5
STILL waiting for the cabinets to be done, but this week I made progress ordering lots of little stuff to finish the build including some tools as well as parts. So the plate amps want to be in a box, and since they CAME in a box, I figured what better box to be in than the box they came in ... + some trimming, ExoHyde, rubber edging, grommets and sleeve for the cables. I did solder the Speakon connections because it just seemed to be the right thing to do. They will go RIGHT behind the subs so the cables stay short, and they'll be pretty much out of sight. View AttachmentVery nice! I think I will wait for you to do all the hard work and then copy you. |
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Post by marcl on Aug 29, 2024 14:03:32 GMT -5
And in case anyone is really upset that my amps will overheat because I put them in cardboard boxes ... fugedaboudit! If you buy the kit from GR you get a wooden box that no doubt will lay flat on the floor. I built these so they stand up behind the subs and the cable plugs into a connector on the first horizontal brace. Convective cooling will be fine ... because they are in the COOLEST room in the house ... in more ways than one I had to explain to my friends (who went to the same engineering school I went to) that these amps are designed to be screwed to a cutout in a sealed subwoofer cabinet made of 1 1/2" MDF and filled with insulation. Not a MICROwatt gets out of those boxes. And ya know what else ... for this application where they are going nowhere ... I even used the screws they gave me to screw the amps to the cardboard  |
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Post by leonski on Aug 29, 2024 17:15:49 GMT -5
QUOTE:
I had to explain to my friends (who went to the same engineering school I went to) that these amps are designed to be screwed to a cutout in a sealed subwoofer cabinet made of 1 1/2" MDF and filled with insulation. Not a MICROwatt gets out of those boxes.
ME? I'd love a temp sensor (thermocouple) INSIDE the speaker box.....Especially given that TOTAL efficiency can't be more than maybe 5% or so......Maybe the voice coil of the woofer is the greatest single heat source here? Certainly, if pushed, it will get worse
with the resistivity of the copper wire rising slightly.....As it heats.
In a cost-no-object test? Several temp sensors and at 'critical' places......
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Post by marcl on Aug 29, 2024 17:22:54 GMT -5
QUOTE: I had to explain to my friends (who went to the same engineering school I went to) that these amps are designed to be screwed to a cutout in a sealed subwoofer cabinet made of 1 1/2" MDF and filled with insulation. Not a MICROwatt gets out of those boxes. ME? I'd love a temp sensor (thermocouple) INSIDE the speaker box.....Especially given that TOTAL efficiency can't be more than maybe 5% or so......Maybe the voice coil of the woofer is the greatest single heat source here? Certainly, if pushed, it will get worse with the resistivity of the copper wire rising slightly.....As it heats. In a cost-no-object test? Several temp sensors and at 'critical' places...... Who does this? Anybody measuring the temperature inside their sub cabinet? Do speaker cabinets have fans in them? Heat happens |
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Post by leonski on Aug 29, 2024 23:31:13 GMT -5
Absolutely! But heat hurts performance in several ways.
VC of speaker rises in resistance.
Amp may have lifetime impacted if TOO hot.....though the designer
better take care of that!
I'd love to know just how high the temp in a sub enclosure reaches......
Than I'd decide level of importance, though with a big box sub? I'd
guess that it would be tough to gett the box THAT hot.......
The value of maybe 5% total efficiency is worrysome. If the amp is
drawing maybe 30 watts? 20+ of that will be HEAT in the enclosure...
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Post by marcl on Sept 2, 2024 14:51:30 GMT -5
Picked up the boxes from Harry today. I’m real happy with the job he did. He even beveled the edges, which was not on the plan but I kind of was hoping he would … he said the straight edge on MDF made him nervous. He didn’t have the speaker mounting holes drilled because he wanted to use an actual speaker – which I brought – and he was nervous about drilling a ¼” hole due to the MDF. I felt like it’s a risk either way … a small pilot hole and then drive a wood screw and risk some issue with that … or the ¼” through hole being close to the edge. But I said, even if the ¼” hole broke through to a slot, with a washer on the back it would be fine. So he drilled four through holes and four pilot holes and I may do a combination. HEAVY bastards! Gotta be close to 100lbs each. Took two full sheets of ¾” MDF and a little ¼”. So tomorrow ... drill a couple holes for wire feeds and the Speakon connector, then drag them to the patio for painting with the Exohyde.    |
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Post by leonski on Sept 2, 2024 18:00:59 GMT -5
My OPINION? I'd have drilled the speaker mounting holes prior to assembly. And I'd have used a drill press.
The material I made my den shelves and desktop out of ? 1" MDF of some sort. Full sheet went 100lb +
Made of of what appears to be sawdust.....not any form of 'chip'.
I may have been Tempted to make the front baffles out of 1" void free birch plywood......
That 100lb each? Once drivers are mounted, that'll zoom!
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Post by marcl on Sept 2, 2024 20:50:41 GMT -5
My OPINION? I'd have drilled the speaker mounting holes prior to assembly. And I'd have used a drill press. The material I made my den shelves and desktop out of ? 1" MDF of some sort. Full sheet went 100lb + Made of of what appears to be sawdust.....not any form of 'chip'. I may have been Tempted to make the front baffles out of 1" void free birch plywood...... That 100lb each? Once drivers are mounted, that'll zoom! Yes I expected he would have drilled the mounting holes before assembly too. But he didn't. He did them on the dining room floor after I talked him into it. He also ended up making the 1" center baffle out of 3/4 and 1/4 because it was too hard to find 1". Looked to me like it drilled fine though it did chip at the exit wound on a couple of them. Remember he's the professional carpenter who builds stuff for a living so I trust his judgement too. But I was afraid of the opposite ... that the wood screws would strip in the MDF. He said it took about a full sheet of 3/4" for each box, and a full sheet weighs 100lbs so yeah they feel like 100lbs each. The drivers weigh 22lbs so I think the 5mm bolts with a flat washer and locking nut should hold just fine. |
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Post by leonski on Sept 3, 2024 0:17:07 GMT -5
You found out the difference between a CARPENTER and a fine woodworker......A 3rd category may be the person who builds BOATS, This requires a different but related set of skills.... . totalwoodstore.com/baltic-birch-marine-grade-plywood-full-sheets-48x96-4-x-8/Above, marine grade (waterproof adhesive, usually) birch of 12 plys or more......VOID FREE. Got a small scrap of your cabinet material for a test? Toss it in some WATER. Density is basically how deep it floats. My stuff was awash meaning over 60lb per cubic foot.... |
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Post by marcl on Sept 3, 2024 9:59:49 GMT -5
Good progress for an hour and a half on this bright, warm, low humidity day! Hard to reach interior corners sprayed flat black; 1" Speakon connector and 3-each 3/4" wire routing holes drilled; parts checked for fit. Now to roll on the ExoHyde which should dry REAL fast in this weather   |
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Post by leonski on Sept 3, 2024 12:55:25 GMT -5
ExoHyde? Is this the solution to my chat with Keith about alternative finishes for EMO speakers?
Tell me more, please.
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Post by marcl on Sept 3, 2024 13:33:11 GMT -5
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Post by marcl on Sept 4, 2024 1:28:21 GMT -5
I say to my sister - personal trainer to the stars - "No pain, NO PAIN!" .... So of Norez they might say "Norez, NO REZ!"  This is not my cabinet ... but see that 1" foam lining the insides of the cabinet? That is Norez. Yes we are told to line the inner walls of H-frame open baffle subs with Norez from GR Research. They sell sheets of it and it's expensive. The sheet has two components: the base is a heavy thin layer that I believe is asphalt (not butyl rubber like Dynamat, and not Mass Loaded vinyl), and bonded to that layer is 1" open cell polyurethane foam. The purpose of doing this is ostensibly to dampen cabinet resonances. Well ... first of all it's a sub and it doesn't play above 120Hz, so we're only interested in cabinet resonance below 120Hz. Let's get this part out of the way first: 1" of open cell polyurethane will not have any effect below 120Hz ... actually not much below 500Hz. Now about that asphalt, yes people use it in vehicles to deaden sound and for thermal insulation. Applied to a metal panel it will certainly deaden low frequency vibration ... as will Dynamat. But, what will it do if it's stuck to 1 1/2" MDF? If anything ... will it have an effect below 120Hz? The speakers aren't finished yet ... is there a way for me to tell if there is a cabinet resonance? Quasimodo! ... what if I take my rubber mallet out to where the cabinets are drying in the sun, open the FFT app in Audiotools on my phone, and tap around the parts of the cabinet? If the cabinet has a structural resonance, shouldn't I see the frequency? Well I did this, and what did I see? The 1 1/2" thick side walls with unbraced sections 6 1/2"x13" rang clearly at 125Hz. The cross braces 3/4" thick 6 1/2"x13" rang (predictably) an octave higher at 250Hz. Now the question is, if this is what I got tapping the structure ... how would it be possible for it to resonate BELOW 120Hz from speaker vibrations below that frequency? I think ... NOT! I will test this. Doing a ground plane measurement with the speaker out in the open back yard and the microphone on the ground 2 meters away - i.e. no room resonances - I should see if there is a cabinet resonance. Measuring on axis and off axis, if there is a resonance it should persist. If I SEE a resonance below 120Hz I will try using Dynamat ... if it works it works. Cool! And if it doesn't ... well, it was worth the experiment because ... SCIENCE ... MATTERS! |
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Post by marcl on Sept 4, 2024 11:27:30 GMT -5
And so that was my quick empirical test and I applied some "ocular regression" and called the resonance of the 6.5"x13"x1.5" side panel 125Hz. Then I thought ... ChatGPT should be able to calculate the resonant frequency of a plate ... and I gave it the dimensions and it churned ... Resonant frequency (with a number of unknown boundary conditions) would be 172.7Hz. Well that is not TOO far off from my 125Hz observation, and it is certainly not below 120Hz. So I went a step further and added the constraint that the panel is rigidly mounted on three sides, with one of the 13" sides left unconstrained. Churned again ... resonance drops to 138.2Hz! I think that corroborates my hypothesis pretty well. Last step will be the ground plane measurement. The calculation ... for your amusement.  |
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So? IMO, 'revert' to Plan A is a non-starter. In my speaker foolings and 
