Midrange Sensitivity Versus Woofer in 3-Way?; New Member 1st Post

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Bogwan

Member
Joined 2006
Hello everyone. I’ve been lurking on this site for awhile (great info everyone!), but this is my first post. Over the post 20 years, I’ve owned and/or listened extensively to many commercially available “high end” (and not so high end) speaker systems. After thinking about it for years, I’ve finally decided to build my first DIY speaker system. My primary goal is to design a speaker system with a realistic tonal balance that does not require auxiliary subwoofers, and I think a 3-way design with 10-inch woofers is the least complex design capable of meeting this goal. Of course, I also want the system to sound detailed yet smooth, provide good dynamics, pinpoint imaging, and accurately reproduce the ambience in the recording. As it is generally thought to be impossible to design a good passive crossover for a 3-way without measuring equipment (which I don’t have - yet), expensive software, experience, and much trial and error, I plan to let either Madisound or Meniscus design the crossovers using measurements and LEAP software. Madisound takes measurements of the individual drives in free space and models their response in a theoretical enclosure using the customer’s cabinet design. Meniscus actually constructs a test cabinet based on the customer’s design and measures the response of the drivers in the cabinet. So Meniscus gets one step closer to reality, which seems good. But these companies have quite different approaches when it comes to midrange sensitivity; so finally, I’m getting to my question. Meniscus recommends choosing a midrange with higher sensitivity than that of the woofer to offset “cabinet gain” for the woofer and to allow more flexibility in the crossover for level matching (i.e. padding down the level of the mid if necessary). Madisound recommends using a midrange with 1-2 dB less sensitivity than the woofer to offset the bandpass gain from the crossover and baffle reinforcement of the midrange output relative to the woofer. Madisound’s recommendations are more in line with what I’ve read in loudspeaker textbooks, but Meniscus also makes a strong case. So, what do you guys think? Should the midrange driver in a 3-way have lower, higher, or the same sensitivity specification as that of the woofer? Also, any general comments from those who have used Madisound or Meniscus to design crossovers would be appreciated. Thanks in advance, Jeff.
 
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sreten

R.I.P.
Joined 2003
Hi,

For a 3-way the bass unit sensitivity needs to be 4 to 6dB higher than
the midrange driver, otherwise the mid driver will need to be padded back.
So Meniscus are way off, Madisound nearer.

Simply put, I don't think your choice of expensively having the crossover
designed for you is a good one, as ever find a good design and copy it.

http://murphyblaster.com/content.php?f=MBOW1_3-WAY.html

Though in my opinion a twin bass unit + mid + tweeter is
more flexible in form factor and gives more driver choice.
In this case the mid does need to be more sensitive than
a single bass unit to give some flexibility, though for full
BSC (6dB) theorectically all drivers are the same.

something like this (or based on something like this) :

http://www.acoustic-visions.com/~acoustic/products/speakers/complete_kits/kit_2641.shtml

:)/sreten.
 
badman

badman

Member
Joined 2003
pothaudio.com
For passive XO, I tend to like 3dB of sensitivity difference or so (3dB more woofer)- compensate for bafflestep without overdoing it and getting yourself too much room gain. I believe that for passive crossovers, one should always make sure to avoid padding the drivers, when possible. Pads are a waste, better to match during the design stage.

Better than all that, is active biamp/triamp, though. then, no need to worry about sensitivity matching at speaker level.
 
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Bogwan

Member
Joined 2006
Thanks for your advice.

The cost for Madisound for design and assemble the crossovers is $40 USD, which is reasonable IMO. Meniscus charges considerably more, $125 USD if you buy the drivers and crossovers from them, $200 USD using components purchased elsewhere. Thanks for the links with example crossovers. I'll consider going it alone.

I also considered using dual woofers wired in parallel as a form of BSC, but I was put off by the added cost and size of the enclosures. The benefits of added overall sensitivity and less electronic BSC might outweigh these drawbacks however.:)
 
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angsuman

Member
Joined 2005
What exactly is your budget for this project? It appears to be pretty high. For learning its best to do a pre designed 2-way or maybe a kit. But if you want very good sound and are wanting to save money compared to commercial designs, then
http://www.rjbaudio.com/
this site has two 3-ways that are well documented.

http://www.rjbaudio.com/Alpheus/alpheus.html

and

http://www.rjbaudio.com/Daedalus/daedalus.html

You could select one based on what you're looking for.

I personally am designing a 3-way with the Vifa XT19 tweeter in the Alpheus.
 
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Bogwan

Member
Joined 2006
Yes, I know that a 3-way is pretty ambitious for my 1st project, but I think it has the greatest chance of success given my preferences. I will check out the kits your referred me to, but I already have some specific drivers and cabinet shape selected at this point. Budget wise, I'm shooting for a total driver cost of $500 USD or less. Not dirt cheap but not over the top either. I'm planning to use Seas Prestige-series drivers.
 
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tinitus

Ex-Moderator R.I.P.
Joined 2005
Six drivers, 500 USD in total, didnt know Seas to be that cheap

And how about listening test and readjustments...or will it be a lucky "hole in one"

I knew a very skilled man who claimed to be able to do that....well sometimes he could

But anyhow,...at least you will have something to work with

BTW....padding midrange is the easy/safe way.....anything else will take some experimenting....and who will choose the right drivers....takes a lot of experience

Actually I dont understand you will do it that way, when you dont do it yourself anyway, so why not choose a proven design where a experienced constructor has paid much more attention and care to details and sound

http://www.troelsgravesen.dk/PMS-EXCEL.htm
 
O

omni

Member
Joined 2006
Bogwan, Please be aware that the cost of $40.00 that Madisound is charging is for CROSSOVER DESIGN ONLY, using their LEAP program. You will still need to purchase the parts, and assemble them yourself. Or if you want them to assemble, there will be a charge.............Regards. Omni
 
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Bogwan

Member
Joined 2006
omni said:
Bogwan, Please be aware that the cost of $40.00 that Madisound is charging is for CROSSOVER DESIGN ONLY, using their LEAP program. You will still need to purchase the parts, and assemble them yourself. Or if you want them to assemble, there will be a charge.............Regards. Omni
Click to expand...

Omni, thanks for clarifying that. I will assemble the crossovers myself on some thin MDF as a mounting board with components held in place by hot melt glue. Crossover boards will be mounted in enclosures with brass screws. Component leads will be soldered together but not twisted for ease of tweaking if necessary. Let me know if you have any other suggestions.
 
B

Bogwan

Member
Joined 2006
badman said:
For passive XO, I tend to like 3dB of sensitivity difference or so (3dB more woofer)- compensate for bafflestep without overdoing it and getting yourself too much room gain. I believe that for passive crossovers, one should always make sure to avoid padding the drivers, when possible. Pads are a waste, better to match during the design stage.

Better than all that, is active biamp/triamp, though. then, no need to worry about sensitivity matching at speaker level.
Click to expand...

I agree that pads are a waste of power, but a 3 dB difference in midrange to woofer sensitivity sounds like a good target to me. Rechecking my notes, Madisound actually recommended the same difference, not 1 - 2 dB as stated in my original post. It would be a bummer to overshoot the sensitivity difference and have excessive output from the woofer, which I understand cannot be padded down without losing bass definition.

I considered going active using a DCX2496 but decided against it due to the complexity of feeding multiple source components (some analog, some digital) through it at the correct level to maximize resolution, attenutating its resulting 6-channel output (preferrably with remote control), and purchasing 6 channels of high quality amplification and cables. There is also the issue of DCX2496 availability. I won't rule it out for the future, but I'm going passive on this project.;)
 
O

omni

Member
Joined 2006
Bogwan, If you use brass screws to mount your crossover board inside the cabinet, use enough of them to completely prevent any chance of the crossover board rattling against the inside wall of your cabinet, or better yet, add a few points of your glue to the back of the crossover board. Low bass response has a tendancy to shake things up a bit, and it would be a bummer to hear an unidentifiable buzz eminating from somewhere. I too am creating a 3 way, sealed enclosure, and am in the process, now, of doing impedance measurements for the final crossover calculations. Good Luck with your project. I have thought about the possibility of getting a crossover designed by LEAP, however thought I might try that next time. I am trying a different approach. Keep us posted..........Respectfully..........Omni
 
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