Dang, it still needs to be tuned lower. I wish the passive I got from Creative Sounds was still available. If you can't tune it lower, I'm not sure the 1db hump would be so bad. My room has 12db peaks and 30db dips. I have a tone of gain around 47hz, so a boost in the 30's flattens things a bit for me. I know it is a matter of group delay too, but I still think you'd probably be happy. I wonder how strict the 500g limit is.
Paul
Paul
Where I you, I would try the MCM passive weighted to 500 grams. If I wasn't happy, I'd add weight to it and see what happened. If you load it fairly heavy, you should consider rotating it 180 degrees every year or so to keep the suspension from completely sagging out.
I noticed PE's cheap 10" has a maximum of 500grams too. You could call PE and MCM and ask if they know whether they will take more weight. I doubt they have any idea. Finally, given the size of your box I assume this is out of the question, but here is the only other passive I found under $50.
http://yellow.mynethost.com/~bv1263...id=40&osCsid=7bd442c8f0fef08435427d804881a094
It's a shame nobody makes a cheap passive that can take the weight. That driver looks nice tuned down in the mid 20's.
I noticed PE's cheap 10" has a maximum of 500grams too. You could call PE and MCM and ask if they know whether they will take more weight. I doubt they have any idea. Finally, given the size of your box I assume this is out of the question, but here is the only other passive I found under $50.
http://yellow.mynethost.com/~bv1263...id=40&osCsid=7bd442c8f0fef08435427d804881a094
It's a shame nobody makes a cheap passive that can take the weight. That driver looks nice tuned down in the mid 20's.
add more mass to lower the sytem tuning....
Voice coil inductance can be simulated for using WinISD pro found at www.Linearteam.org
Voice coil inductance can be simulated for using WinISD pro found at www.Linearteam.org
Hopefully someone smarter will chime in, but I think if both have the same mass, they will be tuned within a few hertz of each other. It looks like the MCM has a bit wider surround, so if the Sd is smaller, it may end up slightly lower. That's just a guess. I didn't have squat for parameters for the passive I used, however the actual tuning almost exactly mirrored the results I got with my very rudimentary calculation.
It's not likely that the +12dB peaks and -30dB dips of a room could be fixed by making small +/-3dB changes to box volume and tuning, or even by changing the driver 
And, on the other hand, such a room will ruin almost any bass system, despite how well it's designed.
Fix the room instead. Put thick carpets in the floor and place shelves full of stuff in the walls. You may as well put some carpers in the walls at random locations. Put a bed and a big armchair if you dont't already have. If you have any windows, put thick curtains on them. That should really improve sound much more than any new speaker. Remember that the room is just another component in the sound chain.
And, on the other hand, such a room will ruin almost any bass system, despite how well it's designed.Fix the room instead. Put thick carpets in the floor and place shelves full of stuff in the walls. You may as well put some carpers in the walls at random locations. Put a bed and a big armchair if you dont't already have. If you have any windows, put thick curtains on them. That should really improve sound much more than any new speaker. Remember that the room is just another component in the sound chain.
Eva said:It's not likely that the +12dB peaks and -30dB dips of a room could be fixed by making small +/-3dB changes to box volume and tuning, or even by changing the driver
Thanks, but this is eag's thread. He/She's the one building the sub here. Does any one have a rectangular room or a two speaker system that doesn't have nulls in spots and room gain in others? From everything I've read my response is pretty typical. Also, my 100 year old plaster walls leak much less bass than most sheetrock construction.
My room has a bookshelf (stuffed with different sizes of books, displayed items and CD's) on one wall, two arm chairs and a big coach. The carpet is dense with high pile. My windows are leaking some bass, but I'm not sure that's bad. They can't reflect much treble where they are, and my mains have awfully limited dispersion so it's further easy to control hf balance.
I think most folks that think they have a flat room just don't have an SPL meter (not saying that's the case with you, just in general.)
I know because I used to do measurements at home with a ECM8000 omnidirectional measurement mic and SpectraRTA software. A well stuffed room full of crap everywhere may show only +6dB peaks and -12dB dips. Anyway, even when the "short term" frequency response does not improve a lot, stuffing rooms is strongly recommended because it reduces quite dramatically bass decay times and standing waves.
quick question: I'm modelling the PR from PE and the unfied excel doc/ software wants to know the "QMP: Q of passive radiator at Fsp due to mechanical resistence." I'm not sure what this is asking for, it does not specify units. Is this the parameter "Qms" in the manufacturers spec. sheet from PE for the PR?
thanks^
I must have had some crazy leaks in my originial design. Here I have the response chart of the vented and PR design (ignored bandpass and closed lines). Granted the final PR design is best, but the vented design is very similar, so I'm trying to figure out why it sounded so light.
I must have had some crazy leaks in my originial design. Here I have the response chart of the vented and PR design (ignored bandpass and closed lines). Granted the final PR design is best, but the vented design is very similar, so I'm trying to figure out why it sounded so light.
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Hey everyone,
Well I bought the buyout amp from MCM and let me just say that the problem I had was from a low powered amp. this bass kicks more from the lowest setting than the 70w had at the highest.
But I do have a slight problem, I haven't truly tested the amp/sub because I am getting noise from the rear of the sub. It sound higher than the freq. coming from the front(where sub is at). I think it is an air leak from the MCM plate amp. I thought the padding on the back of the plate amp would be enough to stop air leaks but I guess not. Should I just add some speaker caulk to the plate amp/box interface? Or just tighten the screws more?
Well I bought the buyout amp from MCM and let me just say that the problem I had was from a low powered amp. this bass kicks more from the lowest setting than the 70w had at the highest.
But I do have a slight problem, I haven't truly tested the amp/sub because I am getting noise from the rear of the sub. It sound higher than the freq. coming from the front(where sub is at). I think it is an air leak from the MCM plate amp. I thought the padding on the back of the plate amp would be enough to stop air leaks but I guess not. Should I just add some speaker caulk to the plate amp/box interface? Or just tighten the screws more?
I'm glad it is working better for you. That buyout amp is a great deal. Keep in mind that even if there were no leaks in your original design, the tiny port was far from ideal.
If you play a 20hz test tone at a decent level (don't break anything, but make sure it is moving some air), you can probably feel air moving at the location of the leak. Try tightening the screws, but don't strip the holes out or you'll be sad. MDF is especially easy to strip. If you used ply, you can get screws awfully snug. The gasket on the plate amp should be enough if all of the screws doing their job.
You should make sure the cab isn't leaking anywhere else too. If you find some leaks to fix you'll be even happier with its performance.
Paul
If you play a 20hz test tone at a decent level (don't break anything, but make sure it is moving some air), you can probably feel air moving at the location of the leak. Try tightening the screws, but don't strip the holes out or you'll be sad. MDF is especially easy to strip. If you used ply, you can get screws awfully snug. The gasket on the plate amp should be enough if all of the screws doing their job.
You should make sure the cab isn't leaking anywhere else too. If you find some leaks to fix you'll be even happier with its performance.
Paul
Ok I can feel the some leaks in the front (sub) but Ill take care of that later. In the back I can here a sort of whistling sound, like that of a weed-wacker. I sealed it with some speaker sealing caulk but it still remains. Perhaps the cable inside are vibrating? I can't feel too much of an airleak in the back but there still is that noise as loud as before.
From taking it out these few times I am starting to strip the mdf. Can I fill in the holes with bondo and redrill for some extra strength?
From taking it out these few times I am starting to strip the mdf. Can I fill in the holes with bondo and redrill for some extra strength?
I'd use hurricane nuts (preferable) or T-nuts. I get hurricane nuts from PE and black socket head cap screws from an online souce (is it bolt depot?) When you need a bunch of fancy bolts it's sure cheaper to buy online than from ACE Hardware. It may be difficult to make them work with the amp, as the holes are small. If you are willing, you may be able to drill out the holes to make it work. It will cost a couple of bucks, but it should be easier than bondo. It will also be a permenant solution (if done reasonably well.)
If you've got bondo and time you can always try it first.
The noise in the back could easily be a tiny leak. If all of the screws are doing their job, the gasket isn't torn and there is nothing wrong with the wood surface, it should work. If you have a screw stripped out, it could be leaking through the hole as well.
Paul
If you've got bondo and time you can always try it first.
The noise in the back could easily be a tiny leak. If all of the screws are doing their job, the gasket isn't torn and there is nothing wrong with the wood surface, it should work. If you have a screw stripped out, it could be leaking through the hole as well.
Paul
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