/sreten.Hi Sreten,
If the present port length gives the correct tuning for a Butterworth alignment, then that will be the flattest response.
I just suspected that as a bass player, Tubehead Johnny might be looking for a little extra oomph around 40 Hz, which is where low E is. And raising the tuning frequency to 40 Hz will give extra oomph from 40 Hz to 80 Hz.
However, it will not be the flattest response, so if you feel there is an interference issue with the mid, by all means address that first.
If the present port length gives the correct tuning for a Butterworth alignment, then that will be the flattest response.
I just suspected that as a bass player, Tubehead Johnny might be looking for a little extra oomph around 40 Hz, which is where low E is. And raising the tuning frequency to 40 Hz will give extra oomph from 40 Hz to 80 Hz.
However, it will not be the flattest response, so if you feel there is an interference issue with the mid, by all means address that first.
First off, we need to know if the 5" is sharing the same airspace as the 12". If it is, massive and somewhat unpredictable interference will take place, possibly diminishing or cancelling output at certain frequencies. A shot in the dark as it pertains to your particular problem, but it is a consideration. If the 5" has its own chamber, good, a mid and woof should never end up in a common chamber. To answer your recent question, any number of dissimilar drivers can be connected in parallel, as long as there is a proper crossover network set up with the correct seperations. Which brings me to the more likely explaination...
If the 5" is running down to ~50Hz and the 12" up to ~200Hz, you have a giant hump or sum in response between 50Hz and 200Hz, with the most gain centered around 100Hz. This will make all other response appear quieter, above and below the hump. With all the other variables (room gain, slope of x-o, standing waves & resonances), output at 80Hz or 100Hz might be 6dB higher or more than at 40Hz. In addition, if the 5" is running down to 50Hz because of your estimation of its low-end rolloff and not because it is high-passed through the x-o, you're dumping half the power in bass into the little guy. This is causing a high load to the amp from 200Hz down, possibly causing it to lose control and compound the problem.
First step is to have the mid in a separate chamber. Second is to fix the overlap from 50Hz to 200Hz by high-passing the mid or running a dedicated amp to the woof. You're not the first person to have done this...
TubeHead Johnny said:
If the 5" is running down to ~50Hz and the 12" up to ~200Hz, you have a giant hump or sum in response between 50Hz and 200Hz, with the most gain centered around 100Hz. This will make all other response appear quieter, above and below the hump. With all the other variables (room gain, slope of x-o, standing waves & resonances), output at 80Hz or 100Hz might be 6dB higher or more than at 40Hz. In addition, if the 5" is running down to 50Hz because of your estimation of its low-end rolloff and not because it is high-passed through the x-o, you're dumping half the power in bass into the little guy. This is causing a high load to the amp from 200Hz down, possibly causing it to lose control and compound the problem.
First step is to have the mid in a separate chamber. Second is to fix the overlap from 50Hz to 200Hz by high-passing the mid or running a dedicated amp to the woof. You're not the first person to have done this...
TubeHead Johnny said:
Why do you claim that the 5.25" covers 50 Hz up? As wired both woofers respond down to DC. The 5.25 is probably displacement limited at about 10W at 50 Hz, whereas the 12" would be about 50W. The 5.25" is limiting your max SPL, or simply adding distortion at high SPL. It is plain wrong. Your XO schematic looks as if it was intended for a 2.5 way where 2 identical woofers are used.
Nice boxes.
Pete B.
I overlooked that the x-o layout was posted earlier. It is indeed a 2.5 way, and totally unsuitable for the drivers being used. I did a quick model with PCD and it's a horrible mess. Response is up by 8 dB or more at both ends ("smiley face" EQ effect). There's a 15dB valley centered ~650Hz, and it spans more than 2 octaves. This is with estimated driver depths but close enough to get the point across. Reversing polarity on the 5" drastically brings up the response at the cost of... drum roll... cancellation at low frequency.
I whipped up a network to the best of my ability if TubeHead Johnny is interested, but I don't know if you're gonna like the cost in parts. My suggestion is to try the Dayton DC130BS-4. By far smoother response and much higher sensitivity. The DA135 is ragged and quiet, not good for what appears to be an attempt at a "lively" set of speakers. I'll take a stab at the x-o if you want...
I whipped up a network to the best of my ability if TubeHead Johnny is interested, but I don't know if you're gonna like the cost in parts. My suggestion is to try the Dayton DC130BS-4. By far smoother response and much higher sensitivity. The DA135 is ragged and quiet, not good for what appears to be an attempt at a "lively" set of speakers. I'll take a stab at the x-o if you want...
fwater-
Instead of the hassle trying to build a chamber in a enclosure that's already glued together, why don't I just buy a real mid range? I was considering the Dayton DC50F-8 2" Dome Midrange, which will fit perfectly in the existing 4.5" hole:
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=285-010
Thanks everyone for all your informative (but sometimes condescending) advice!
~John~
Instead of the hassle trying to build a chamber in a enclosure that's already glued together, why don't I just buy a real mid range? I was considering the Dayton DC50F-8 2" Dome Midrange, which will fit perfectly in the existing 4.5" hole:
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=285-010
Thanks everyone for all your informative (but sometimes condescending) advice!
~John~
Out of stock but you might find them from another supplier:
http://www.madisound.com/catalog/product_info.php?manufacturers_id=149&products_id=8271
http://www.madisound.com/catalog/product_info.php?manufacturers_id=149&products_id=8271
"Thanks everyone for all your informative (but sometimes condescending) advice!"
This isn't the first time I've been taken as condescending. It's a flaw in the way I write; I assure you that I mean no ill will. We were all at a point where we knew just enough to be dangerous but not enough to get things right the first time. When I point that out, it's an attempt to be helpful, definitely not to poo-poo your work or to talk down to anyone. For instance, you've done a fine job on the enclosures, and your choice of low cost but reasonable performing drivers is miles ahead of many newbies.
The Dayton 2" is not a bad choice, certainly cost-effective. The only drawback would be integrating it into the current enclosure. I don't know your skill level with wood, but if you can pull it off, great.
http://www.speakerbuilder.net/web_files/Projects/Lyra/lyramain.htm
This design is well-recieved and uses the mid an tweet your looking at. I would be fairly confident that the x-o would not need to be changed to make the jump to a 12" instead of the Lyra's 10". Wayne J (the designer) knows what he's doing. I am still willing, however, to whip up a network if you're more interested in a different mid or a simpler layout. It's down to your budget, basically.
BTW, the fact that the Lyra is a closed box and yours is vented should be no problem at all. The difference will be more bass, something it seems you're interested in anyway.
This isn't the first time I've been taken as condescending. It's a flaw in the way I write; I assure you that I mean no ill will. We were all at a point where we knew just enough to be dangerous but not enough to get things right the first time. When I point that out, it's an attempt to be helpful, definitely not to poo-poo your work or to talk down to anyone. For instance, you've done a fine job on the enclosures, and your choice of low cost but reasonable performing drivers is miles ahead of many newbies.
The Dayton 2" is not a bad choice, certainly cost-effective. The only drawback would be integrating it into the current enclosure. I don't know your skill level with wood, but if you can pull it off, great.
http://www.speakerbuilder.net/web_files/Projects/Lyra/lyramain.htm
This design is well-recieved and uses the mid an tweet your looking at. I would be fairly confident that the x-o would not need to be changed to make the jump to a 12" instead of the Lyra's 10". Wayne J (the designer) knows what he's doing. I am still willing, however, to whip up a network if you're more interested in a different mid or a simpler layout. It's down to your budget, basically.
BTW, the fact that the Lyra is a closed box and yours is vented should be no problem at all. The difference will be more bass, something it seems you're interested in anyway.
My bad PB2. I thought you where to referring to the midrange I was looking at, not the chamber cup you found at Madisound.
pwater,
The Lyra XO looks good. I just might do it! I get great satisfaction coming up with my own ideas and projects....I just don't have the abilities to design my own crossover (I think you know that by now
) Not right now anyway. I'm gonna make up a parts list to see how much $$$ I need.PB2 said:
My guess is that "frequency range" spec on his mid is "50 Hz to 2,000 Hz" or some such. Actually, it is a custom for inexpensive speakers which don't have the Thiele-Small specs available to list the Fs as the lower number of the "frequency range". Of course, in truth his -3 dB down point of this speaker will depend on the enclosure it is in.
Since it has been established the mid does not have a separate chamber, and the Vas of most any 5.25 in speaker is much, much less than the 3.8 ft³ of the main enclosure, the lower frequency range might well be around 50 or 60 Hz, unless the Qts is quite low.
If the 5.25 in mid is unchambered, as has been established, there is the possiblity that it is working as a passive radiator for the 12" woofer/box combo. If you put two nonidentical ports or PRs into one chamber, the Port or PR which would serve to tune the box to a higher frequency will prevail and the box tuning will go up.
In other words, if the 5.25 in mid is acting as a passive radiator tuning the box to 50 or 60 Hz, then the 4" tube which Tubehead Johnny thinks is tuning his box is doing little or nothing at all.
I propose a simple, easy-to-do test. I would suggest Tubehead Johnny put the two speakers right next to each other in a room, and use a freeware online tone generator to generate a 40 Hz tone. Here is a good one, SweepGen:
www.satsignal.net => Audio Tools
He can either run the 40 Hz tone from his computer sound card if convenient, or simply make a CD of a 40 Hz tone and bring it to the room where his speakers and sound equipment is all hooked up.
Then Tubehead J should remove the 5.25 in mid from ONE speaker and leave the other speaker alone. He should take a towel and plug the 5.25 in hole in the speaker the mid was removed from. Then run the 40 Hz tone first in one speaker, then the other.
If he gets significantly more bass output at 40 Hz from the speaker with the midbass removed and the hole plugged, then he has found his problem. He still has to deal with range of the two speakers overlapping, but at least he knows his speaker system has the potential to produce the bass he wants if hooked up right. And the test only takes a few minutes.
In other words, if the 5.25 in mid is acting as a passive radiator tuning the box to 50 or 60 Hz, then the 4" tube which Tubehead Johnny thinks is tuning his box is doing little or nothing at all.
I propose a simple, easy-to-do test. I would suggest Tubehead Johnny put the two speakers right next to each other in a room, and use a freeware online tone generator to generate a 40 Hz tone. Here is a good one, SweepGen:
www.satsignal.net => Audio Tools
He can either run the 40 Hz tone from his computer sound card if convenient, or simply make a CD of a 40 Hz tone and bring it to the room where his speakers and sound equipment is all hooked up.
Then Tubehead J should remove the 5.25 in mid from ONE speaker and leave the other speaker alone. He should take a towel and plug the 5.25 in hole in the speaker the mid was removed from. Then run the 40 Hz tone first in one speaker, then the other.
If he gets significantly more bass output at 40 Hz from the speaker with the midbass removed and the hole plugged, then he has found his problem. He still has to deal with range of the two speakers overlapping, but at least he knows his speaker system has the potential to produce the bass he wants if hooked up right. And the test only takes a few minutes.
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