# Possible 3 Way Bookshelf? Thoughts ? Anything appreciated



## braves6117 (Feb 13, 2008)

Hey Guys,

I don’t have a clue when it comes to bookshelves, so all the help and time is truly appreciated. I also apologize for being ignorant with my questions, I am the first to say I haven’t spent enough time searching.

I have some extra equipment lying around, and thought maybe it could be a good three way bookshelf system.

What are your thoughts?

Tweeter: Vifa D26NC-15-06

Mid: Morel MDM55

Woofer: Either B&C 6NDL38 or Usher 8945P (whichever doesn’t make it to my vehicle.)


If you guys think it would work, where can I have a crossover designed and made for this setup?

For speaker cabinets, I’m thinking Mr. Marv? But how do I know what cabinet size I need and whether it should be ported/sealed?

Thanks again.


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## GlasSman (Nov 14, 2006)

If the cabinet has enough airspace there shouldn't be any problems.

Once the cabinet gets past a certain size it's not really a _*bookshelf *_speaker speaker per se....it's just a small speaker.


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## MiniVanMan (Jun 28, 2005)

That's a big project for a first time DIYer.

Did you decide not to use the MDM-55 in your car?

The MDM and DC26 are small enough to be able to effectively do a bookshelf.

There would be a ton of things that would have to be hashed out. Would be a lot of benefit to a system like that. Definitely one of them being high efficiency. 

I'd highly recommend a tower and another pair of 8945Ps if that's the midbass you end up with.

Again, why aren't you using the MDM in the vehicle.?


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## braves6117 (Feb 13, 2008)

MiniVanMan said:


> That's a big project for a first time DIYer.
> 
> Did you decide not to use the MDM-55 in your car?
> 
> ...



Hey MiniVanMan.

I screwed up my measurement regarding the depth of the MDM by half an inch, and therefore it extends past the plane where the window goes up and down  And I did measure twice..such a dumass move.

Normally, I would extend the mid half an inch in cabin, but with new door cards and no grill, I can't.

A tower setup is perfectly fine with me. I feel the hardest part about this is my lack of knowledge of how to design, or where to resource my crossover, towers, ect....

I'm almost certain I'll be installing the B&C's in my vehicle, so the ushers would be for a tower design...

What's the reason behind another pair of woofers for the tower? If thats what it takes to make it happen, I'm willing to get another. It's time I had a nice setup for room listening and would be a huge plus to say I did it myself. 


And, am I biting more then I can chew here.....:worried:


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## braves6117 (Feb 13, 2008)

The last post makes it seem I'm leaning away from attempting something like this. Please don't take me wrong, this actually gets me anxious to try it, but I can't get anywhere without the great folks here.

Just look at my car audio transition from when I first arrived until now....jobs during college funded that hobby alone, however, the forums knowledge actually made it happen.


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## MiniVanMan (Jun 28, 2005)

Well, this is where the **** gets serious. 

If you're willing to do some research and work, I'm willing to help you along, guide you and check your work.

The reason for the second woofer is for Baffle Step Compensation. Due to a limited width baffle, you'll lose about 6 db of output from your midbass. The 6 db loss occurs starting around 100-150 hz all the way to about 1 khz at a slope. 

Take a look at this thread at the graphs where I talk about BSC.

http://www.diymobileaudio.com/forum/diyma-tutorials/17429-basic-guide-crossovers-part-2-a.html

The second woofer combats the 6 db loss resulting in higher efficiency. If you want to give up efficiency for smaller size, then you can adjust the BSC via the crossover network. If you're using a high efficiency dome though, you'll want the extra efficiency from your mids.

If you wanted to keep it bookshelf sized, then you'll lose that efficiency. If you use the B&C drivers you'd be in a better situation for a bookshelf.

Of course in a situation like this, when using a midrange, baffle step is considerably less depending on the high pass of the midrange. 

This is also dependent on where you locate the speakers. A properly built BSC network will require you to move the speakers away from the wall about 18"-24". If you don't you'll end up with some bloated bottom end. 

It's complicated at first, but once you understand it, it's actually pretty simple.

Baffle Step Compensation


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## braves6117 (Feb 13, 2008)

MiniVanMan said:


> Well, this is where the **** gets serious.
> 
> If you're willing to do some research and work, I'm willing to help you along, guide you and check your work.
> 
> ...


Wow, what an excellent thread, one of the best "information of value" in a long time. 

I now have a grasp of BSC, and the necessity of compensation via crossover design. I never understood the design behind a passive crossover nor its purpose for one driver in mind. I mean, I understood the reason you couldn't switch between speakers, but after reading that info, how can one ever rely on a passive setup for a vehicle?? And to see how the value of the budget minded RS180 goes down because of the crossover design was eye opening at the same time. 




MiniVanMan said:


> The second woofer combats the 6 db loss resulting in higher efficiency. If you want to give up efficiency for smaller size, then you can adjust the BSC via the crossover network. If you're using a high efficiency dome though, you'll want the extra efficiency from your mids.
> 
> If you wanted to keep it bookshelf sized, then you'll lose that efficiency. If you use the B&C drivers you'd be in a better situation for a bookshelf.
> 
> ...


I don't want to keep it bookshelf size, I was being ignorant to think such response could be achieved with that size and these drivers. Towers are just fine, and will be placed at whatever necessary distance from walls.


I'm seeing double now, so I'll be brief...

So, we not only need "non harmonic" positioning of the drivers, but we'll also have to have the baffle size designed somewhat before being able to calulate a circuit that combats the baffle step? 

This is a whole new ball game  It's getting fun


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## MiniVanMan (Jun 28, 2005)

braves6117 said:


> but we'll also have to have the baffle size designed somewhat before being able to calulate a circuit that combats the baffle step?
> 
> This is a whole new ball game  It's getting fun


You'll need the baffle size designed.... period.

Here's the order you design in.

1 - Enclosure Volume (for the woofer)
2 - Outer Enclosure Dimensions
3 - Driver placement on the baffle
4 - Crossover Network

Each and every one of those is critical to the final outcome.

Now, you can do this one of two ways. You can do it the right way, or you can do it the quasi right way. The right way is to get measurement equipment and software and measure and test during each process.

The quasi right way is to just model it. This is delicate because one typo can screw everything up. It's important to check your work over and over and have somebody else check it. 

Here's a great site that walks you through the modeling process.

FRD Consortium tools guide

Now, there are some hiccups. If you remember in the other thread there were some discrepancies in measurement data between different sources pointed out. It's always a good idea to measure your drivers yourself to get valid T/S parameters. 

There are a number of ways to do this. The Dayton WT3 Woofer Tester is a great way. We can work that one out though. Point being, when designing your enclosure you need the most accurate data possible. 

Finally, ATTENTION TO DETAIL!!!!!! Enclosure design is a true art. You can make it as complicated as you want, but it's never simple. There are so many things you can do to affect the overall sound and output of your loudspeaker. It's not as simple as building a box, cutting some holes and slapping some drivers in there.


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## Hillbilly SQ (Jan 26, 2007)

To throw a wrench into braves towers how hard would it be for him to do a 3.5 way design? After reading up on the benefits it make a lot of sence. Pretty cool concept.

May I also suggest a solderless breadboard and a bunch of extra parts that deviate the final result a little bit in either direction for the ultimate in custom passive design?

I'll be following this thread closely and most likely take on a custom passive design for the home myself when the time is right. For now I'm going by someone elses design with usher mids and tweets. Aerobic program for the brain ftw!


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## MiniVanMan (Jun 28, 2005)

Hillbilly SQ said:


> To throw a wrench into braves towers how hard would it be for him to do a 3.5 way design?


Hard as hell. It'd be fun though.


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## Hillbilly SQ (Jan 26, 2007)

MiniVanMan said:


> Hard as hell. It'd be fun though.


That's why I'd have a solderless breadboard and a bin full of parts in my lap while kicked back in the recliner:laugh:Sounds like it would be a good project for when I retire in 30-40 years. Gotta fight off alzheimers somehow


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## seagrasser (Feb 6, 2007)

Found a nice cabinet for you if you are willing to change the tweeter.

DIY 3 way Speaker Cabinets - eBay (item 130288878218 end time Mar-21-09 12:16:03 PDT)


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## braves6117 (Feb 13, 2008)

Thanks for the responses gentlemen. 

As of now, the dedicated woofer will be the B&C 6NDL38. Until I can get another pair, and finish with the car, this will be my next project 

There is A LOT more to learn before then, so resources are best at the moment. A special thanks to MVM for what he has already taught me.


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## Ga foo 88 (Dec 18, 2005)

Homebrew speaker project resources - SSA Forums:

I think it would be unwise to at least not browse some tested designs. The complexity and the cost of the crossover components could potentially put a damper on this project.


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