C.Pop's New & Improved 21" Mega Journey of Foolishness (with PR's) - Page 4 - AVS Forum | Home Theater Discussions And Reviews
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post #91 of 118 Old 05-27-2020, 09:26 AM - Thread Starter
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Just got an email from PSI saying they're done. $190 shipped -but this is after I supplied the frame to them.

It'll be a while before that arrives, but should be fun to compare to the Mach5.

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post #92 of 118 Old 05-27-2020, 10:49 AM
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Options are always good, especially for a product that was slim to none.
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post #93 of 118 Old 05-28-2020, 02:33 PM
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Originally Posted by Chris Popovich View Post
I'm pulling a TON out up top but it still has punch and impact, TONS of midbass, I have so much midbass I don't even know what to do with it.
This is why I don't get the point of the devastator design or any mbm for that matter. Most people looking for midbass are really looking for near field tactile response. I'd imagine for those seeking that, simply putting your regular main subs behind the couch should be optimum. A simple ported design is going to bring out the bottom end and have no issues with midbass when using pro driver 21's. PR's give you that with less bulk and no vent noise with a slight efficiency penalty.
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post #94 of 118 Old 05-28-2020, 02:43 PM - Thread Starter
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I'm with you. We need more sensitivity and output below 30hz. Midbass is easy, always has been IMO. Doesn't mean there isn't a place for a high motor strength/high efficiency woofer -I'm using 'em! Just focus on the hard stuff.
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post #95 of 118 Old 05-29-2020, 07:28 AM
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Originally Posted by SpinMonster View Post
This is why I don't get the point of the devastator design or any mbm for that matter. Most people looking for midbass are really looking for near field tactile response. I'd imagine for those seeking that, simply putting your regular main subs behind the couch should be optimum. A simple ported design is going to bring out the bottom end and have no issues with midbass when using pro driver 21's. PR's give you that with less bulk and no vent noise with a slight efficiency penalty.
You may lose port noise but you also gain mechanical noise.


Also the midbass often shows a lot more issues in room than ULF in my experience. Some subs just aren't good for fixing midbass issues, especially 40hz and up. I know you mentioned the pro 21's and I have to agree, by just switching to the Eminence NSW I fixed pretty much every issue I had and they are in 24x25.5x41" boxes tuned to 17hz.
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post #96 of 118 Old 05-29-2020, 08:30 AM - Thread Starter
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There may be exceptions but my general experiences have been that PR's are lower "noise" alignments than ported. It's not difficult to make a quiet passive and resonances, chuffing, and bleeding all go away. Of course there are good and bad examples of both.
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post #97 of 118 Old 06-04-2020, 11:09 AM - Thread Starter
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PSI unit showed up today. It's a very nice unit. Pics of the PSI attached below.

$190 after I send them the frame, which cost me $75 or $85, and was damn near $100 to ship. If I could get the frames shipped directly to PSI the idea would be more viable. This *should* be possible for any of you trying to do this, but not for me first go-around (pain of learning).

PSI Things I like:
Build quality is fantastic (heavy duty... inspires confidence)
Mass fastener hardware is stout

PSI Things I don't like:
Have to supply own frame
Timeline is very long
Price is significantly higher than the Mach5 with extra steps required to obtain final product ($190 USD to make/ship PR once frame is supplied)
Mass is not included
No TS specs provided



Mach5 Things I like:
Build quality is good
Communication is good
Timeline is reasonable
Price is reasonable ($250 canadian shipped)
Mass is included
TS specs provided and real world results appear to follow model fairly well
Mark is willing to make custom changes, at least in the direction of end use. For example I said I wanted to load 3kg, and on the subsequent PR's he'll add some mass to the front of the cone to balance things better. That's cool.

Mach5 things I don't like:
21" frame is a waffle design on backface, which makes sealing to box more difficult.
Hardware to fasten mass is adequate but I'd prefer a touch more stout.
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Last edited by Chris Popovich; 06-04-2020 at 11:17 AM.
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post #98 of 118 Old 06-04-2020, 05:54 PM - Thread Starter
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For the reasons listed above I've asked Mark at Mach5 to send me 4 more PR's. Why four when I already have one of his? Because he's going to add mass to the front of the cone for better balance, and I want them all to be the same.

If there is interest, I can load and test the PSI unit, maybe try to get some workable TS parameters. Or if anyone wants it as-is brand new that's an option too.


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post #99 of 118 Old 06-04-2020, 06:11 PM
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Can we get some side by sides of Mach 5 v PSI?


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post #100 of 118 Old 06-04-2020, 07:38 PM - Thread Starter
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They are visually almost identical, and it's not worth comparing frames because I supplied my own frame to PSI. I'll stick 'em side by side sometime and snap a pic.

One thing that escaped me, is that Mark at Mach5 has a stamped steel frame available that doesn't throw as far but pulls cost down a little more. It's adequate for these pro-drivers, unless you go super low tuning with boost, or really using all the power they'll handle.
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post #101 of 118 Old 06-12-2020, 07:54 AM - Thread Starter
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Update: Changed order to 8 21" PR's from Mach5. hehehe
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post #102 of 118 Old 06-12-2020, 08:01 AM
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Cue fireworks! This should cover all bases.
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post #103 of 118 Old 06-12-2020, 09:17 AM
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Update: Changed order to 8 21" PR's from Mach5. hehehe
Wow!!!

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post #104 of 118 Old 07-01-2020, 11:10 AM - Thread Starter
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Minor update: Spent some more time calibrating the test box. It's pretty damned good. Impact is fantastic, does midbass extremely well and the bottom end is strong -I use a room curve that's pretty aggressive. Even with just the one test box I find I'm using less of the subharmonic synth than the previous setup. Very clean, great punch. Almost begins to startle you at high volumes with the transient punch, very very dynamic. I suspect that with a planned 8 drivers my SPL needs will be met. Maybe even with just 4.

Got a tracking number from Mark, 8 PR's are shipped and on the way to the good 'ole US of A. Probably will show up next week. Mark used some gloss black dust caps to cover up the 1kg he mounted to the front of the cone for the 3kg total mass to be better balanced (for longevity). I'll post pics when they come in.
I think I cleaned him out of 21" frames and the large dust caps.

I'd like to go dual opposed at least on the PR's for force balancing reasons, but I think if one had enough of these you could get by with active driver/PR opposed, of course you'd probably have to mass-load the cabinet and use some good pads under the box -she will dance at higher volumes and very low freq's.

Now I'm just fooling around with designs and concepts. Pretty much know what I want to do for box volume. The question is do I want to make the whole box dual opposed, with the LaVoce on top and PR on bottom, front and back, or do I want the Lavoces front firing with PR's side firing (dual opposed)? Or two of each?
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post #105 of 118 Old 07-01-2020, 01:10 PM
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Originally Posted by Chris Popovich View Post
I'd like to go dual opposed at least on the PR's for force balancing reasons, but I think if one had enough of these you could get by with active driver/PR opposed, of course you'd probably have to mass-load the cabinet and use some good pads under the box -she will dance at higher volumes and very low freq's.

I'm sure you're aware, but lest someone less knowledgeable draw the wrong conclusion, this won't give significant force-canceling - the PR is much heavier and at the freq where it moves the most, the driver moves the least.

Also, have you calculated the PR's sag if downfiring?

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post #106 of 118 Old 07-01-2020, 04:38 PM - Thread Starter
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I'm sure you're aware, but lest someone less knowledgeable draw the wrong conclusion, this won't give significant force-canceling - the PR is much heavier and at the freq where it moves the most, the driver moves the least.

Also, have you calculated the PR's sag if downfiring?
Right, I'm stating based on my experience driving the snot out of a single PR in a 6cuft box with a single lavoce... you could get it to be still enough if you added some mass to the cab. Definitely not like a force balanced design, and definitely wouldn't work with a driver you can push harder (eminence for example).

Negative on the PR sag, I have not ever had intentions of running a PR downfiring, especially when loaded with 3kg of additional mass. You could probably do it if the box were big enough to not need to add much mass to it but that would be a HUGE box.
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post #107 of 118 Old 07-01-2020, 05:41 PM
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Negative on the PR sag, I have not ever had intentions of running a PR downfiring, especially when loaded with 3kg of additional mass.

OK, I guess I read this wrong then:

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The question is do I want to make the whole box dual opposed, with the LaVoce on top and PR on bottom...

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post #108 of 118 Old 07-01-2020, 05:55 PM - Thread Starter
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There are 4 drivers in the design; two lavoce and two PR's. In the dual opposed config the lavoces would be dual opposed on the top front (and rear) faces of the box. The PR's would be dual opposed on the bottom front (and rear) faces of the box. So only 2 faces of the box would have drivers, and there would be one of each on those faces. Make sense?

Right now I'm thinking front firing for lavoce, and side firing for the PR's. Three faces of the box have drivers.

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post #109 of 118 Old 07-01-2020, 06:49 PM
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Got it, just like Tom Danley's Contrabass subs.

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post #110 of 118 Old 07-01-2020, 07:08 PM
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The classical design is more popular, front mounted drivers with PR's on the sides. Having dual opposed Lavoces might have its advantages, like less box vibration. I believe I saw a design a few years ago by FunkAudio which had dual opposed PR's and drivers.
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post #111 of 118 Old 07-02-2020, 01:17 PM
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I just used 18" passives with a 21" B&C. https://www.avsforum.com/forum/155-d...p1-4000-a.html

I don't know if AE makes passives anymore though.
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post #112 of 118 Old 07-02-2020, 05:28 PM
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Stereodude, that's a nice build you did, I'm sure you're enjoying them.
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post #113 of 118 Old 07-03-2020, 05:00 AM
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I just used 18" passives with a 21" B&C. https://www.avsforum.com/forum/155-d...p1-4000-a.html

I don't know if AE makes passives anymore though.
John will still apparently make them custom. When I was looking recently the cost would have been at least double after FX conversion, shipping, brokerage fees, etc.

But the ones you have look like his aluminum ones, gorgeous. Not sure he makes those anymore.

 

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post #114 of 118 Old 07-03-2020, 10:24 AM
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with all that mass added to the pR, how does the cone hold up at higher excursions? I remember AE PR's were made with MDF/Plywood, wouldn't this approach be more robust?
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post #115 of 118 Old 07-03-2020, 10:29 AM
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John will still apparently make them custom. When I was looking recently the cost would have been at least double after FX conversion, shipping, brokerage fees, etc.

But the ones you have look like his aluminum ones, gorgeous. Not sure he makes those anymore.
The outside part looks to be painted MDF + a rubber surround. Or were you referring to some other part of them being aluminum?

They were only $125 each back when I bought them (excluding shipping which wasn't much for the 4).
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post #116 of 118 Old 07-03-2020, 10:33 AM
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with all that mass added to the pR, how does the cone hold up at higher excursions? I remember AE PR's were made with MDF/Plywood, wouldn't this approach be more robust?
Well, they still have a spider. They MDF is plenty stiff for the low frequencies they oscillate at. The ones I used (1600g) have no mass added. It's basically all just in the MDF
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post #117 of 118 Old 07-03-2020, 11:50 AM
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The outside part looks to be painted MDF + a rubber surround. Or were you referring to some other part of them being aluminum?

They were only $125 each back when I bought them (excluding shipping which wasn't much for the 4).
Thought he made the cone out of spun aluminum way back when similar to the AV15H... Maybe not. But I like the clean cone look with no dust cap regardless.

 

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post #118 of 118 Old 07-03-2020, 12:18 PM - Thread Starter
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with all that mass added to the pR, how does the cone hold up at higher excursions? I remember AE PR's were made with MDF/Plywood, wouldn't this approach be more robust?
I had some of the old 2500g PR's from AE that were MDF. Doesn't tremendously matter. The mass just controls where the PR wants to resonate, it doesn't have as much impact on cone integrity as you'd think. A bigger concern is longevity and sagging, but with no coil to rub could probably get away with more slop there anyway.

With this much surface area, excursion is controlled very well and with the power I'll be giving them, it'll be very reasonable. If I can drive the frequency down a touch further I think I can get by with no dsp added hpf.


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