# Potential DIY Bookshelf speaker idea!!



## peenemunde (Aug 31, 2013)

I bought a Polk Audio SR6500 component set that is intended for my SQ build. I plan to run the speakers actively on my DRZ9255, this leaves me with crossovers sitting in my closet. After recently purchasing a Harmon Kardon receiver a while ago, I decided to hook into my computer through optical and use it for gaming. The speakers I have are junk and I wanted to upgrade anyway, so why not DIY some myself?! 

Which leads me to my point. Can I buy some partsexpress raw drivers and use these car audio crossovers? I was thinking I would build enclosures to spec, or potentially ask a professional for enclosure design based on crossover/driver capabilities. Then run each speaker to a binding post and use these crossovers externally. The specs are listed below. 

I thought maybe someone would have insight as to whether anything with these specific crossovers would make building a loudspeaker plausible or not. Just a fun winter project, but I need input or speaker recommendations before I can get this build under way

2nd order, 12dB per octave low pass filter for the woofer 
3rd order, 18dB per octave high pass filter for the tweeter
Crossover frequency for both the high-pass and low-pass is 3100 Hz

Also, the tweeter has a -3db, -1db, 0db, +1db setting for fine tuning as I see fit 
The HK Receiver is 45watts per channel in 2channel stereo


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## Lyferxb9s (Dec 26, 2012)

I have done similar before with good results. I say go for it.


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## peenemunde (Aug 31, 2013)

How hard will it be to design an enclosure that will allow the drivers to roll-off naturally? 

I've read the SR tweeter was loosely designed around the Vifa XT25 platform, so I thought I would start there when choosing drivers.. However, this is all still very new for me. I've never built anything related to home audio nor have I ever worked with raw drivers

Any and all info would be very much appreciated  Cabinet design, do's and dont's, wood choice, anything that may be beneficial in deciding if this will be my winter project!! 

Thanks


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## peenemunde (Aug 31, 2013)

Now I got all excited and had to look into midbass speakers to blend with the Vifa XT25... 

Mind you, this is all speculation and a few hours of hypothesizing 

These two options immediately jumped out at me. Something that will be smooth up to 3100hz 

https://www.madisoundspeakerstore.c.../silver-flute-w17rc38-04-ohm-6-1/2-wool-cone/

https://www.madisoundspeakerstore.com/hi-vi-woofers-6-7/hi-vi-l6-4r-6-woven-kevlar-cone-4-ohm/


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## Lycancatt (Apr 11, 2010)

you might consider an mtm design to maximize cone area and bass response. something like the Dayton reference 6.5 drivers which are eight ohm, wired in parallel to give the crossover the 4 ohm load its expecting, paired with the vifa tweeter. You don't have too much power so you might like to oversize the box slightly to increase efficiency down low.

I have a pair of similar speakers using vifa 6.5 woofers from dcm cabinets found at goodwill, and an electrovoice large format tweeter, plus a dayton 2khz crossover, and it is a great speaker for casual listening and gets stupid loud..like loud enough to keep up with a single 18 sub getting a lot of power. The boxes are oversized and with some parametric boost reach to 30 hz.


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## peenemunde (Aug 31, 2013)

Lycancatt said:


> you might consider an mtm design to maximize cone area and bass response. something like the Dayton reference 6.5 drivers which are eight ohm, wired in parallel to give the crossover the 4 ohm load its expecting, paired with the vifa tweeter. You don't have too much power so you might like to oversize the box slightly to increase efficiency down low.
> 
> I have a pair of similar speakers using vifa 6.5 woofers from dcm cabinets found at goodwill, and an electrovoice large format tweeter, plus a dayton 2khz crossover, and it is a great speaker for casual listening and gets stupid loud..like loud enough to keep up with a single 18 sub getting a lot of power. The boxes are oversized and with some parametric boost reach to 30 hz.


That sounds like fun  
I'm really hoping this idea takes off over the winter. Sounds like a fun project.. However, I've never designed an enclosure for something like this. 

Anyone with experience in such things care to chime in?


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## schmiddr2 (Aug 10, 2009)

Might consider these: Celestion Neodymium 5" Full-Range Woofer 4 Ohm


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## cajunner (Apr 13, 2007)

I would first reverse-engineer the crossovers from Polk, get their specific characteristics out in the open and then see what resistor/impedance matching is going on, so I could at least get the sensitivity of the new drivers to fit into the scheme. 

you're going to have a much smaller selection of raw, OEM drivers to choose from when you consider you are shooting for sensitivity matching, along with 4 ohm drivers.

I'd probably spring for a simple first order coil and cap (cheapest parts) to see if the Polk's crossovers are necessary or if they actually do not help the sound, by comparing the two networks against each other.

if that sounds like too much then forget about things like impedance and sensitivity and just pick up some speakers you can afford and hook it up, and see what you got. Chances are it won't be as good as something cheap off a Best Buy shelf but it will play and it will be at least decent.


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## lostthumb (Dec 16, 2005)

Have you thought about buying a proven speaker "kit". 
For budget ones, check out the "Overnight Sensations". They have received many good reviews.

To me, "kit" speakers are fun. You do the actual work but will yield a great sounding project.


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## sirbOOm (Jan 24, 2013)

Need to match ohm loads to the crossover based upon the ohm of the polk speakers (the tweeter and the woofer) but yes you can do this. I do this using some crossovers that were taken out of a customer's car that he didn't want... Memphis Audio something. Much easier than building crossovers and the hell if I'm looking for the best SQ's from my office pooter.


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## peenemunde (Aug 31, 2013)

My idea behind this was to use my Polk crossovers for something useful and give myself a winter project. I don't expect these speakers to be the best thing around  

Also, having realized the crossover needs a 4 ohm load, I'll have to find another amplifier as my HK is 8ohm and doesn't like anything below. So chances are, these will find a home on a small desktop amp such as Lepai or something along those lines. 

Overnight Sensations looks like a wicked good kit, and is essentially what I'm looking to do. However, I really want to use my crossovers and the Vifa tweeter.. I was thinking the Dayton RS midwoofer but I've heard they have bad cone breakup between 2500-3000 and that won't work for my crossover. That 5" fullrange posted above looks promising 

I like the idea of a big 4th order MTM design but I think the enclosure design would be extremely hard for a noobie such as myself.. I may just stick to a 2way bookshelf design for now and use them as a desktop setup


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## jdsoldger (Feb 14, 2012)

When you design and build a speaker, the last thing you do is design the crossover to make all the parts work well together (you pick the crossover frequency based on driver characteristics). Starting with a crossover is about the most backwards way you can build a speaker. Get the crossover right, and even crap drivers can sound decent. Get the crossover wrong and you can make the best drivers sound like a steaming pile...

Also, I can toss another vote for the Overnight Sensations. I built a pair with a small built in chip amp for travel. They punch waaaaaay above their price and are some of the best sounding little speakers I have heard.


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## peenemunde (Aug 31, 2013)

The whole reasoning behind my idea, is that I had the crossovers and the Vifa XT25 so closely matches the polk tweeter that I figured it wouldn't be too hard to find a good midbass to pair up with the Vifa and have a rockin 2way bookshelf speaker for my computer. However, finding a 6" midbass/midrange that plays comfortably up to 3100hz(Polk crossover) is hard. 

I may just skip out on the idea entirely. I just picked up an IDQ 15" V2 that would be great for a home theater sub... I was thinking 8th order ABC box tuned at 30/60Hz... Either BASH [email protected] or Crown [email protected] (Bridged)

I smell fun and coils all at the same time


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## Victor_inox (Apr 27, 2012)

6500 crossovers engineered and build better that 95% of mainstream home audio speakers use. known impedances and crossover points makes it very easy proposition to build nice bookshelves or towers.
MTM or D`Appolito design would be close to optimal.


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## peenemunde (Aug 31, 2013)

Victor_inox said:


> 6500 crossovers engineered and build better that 95% of mainstream home audio speakers use. known impedances and crossover points makes it very easy proposition to build nice bookshelves or towers.
> MTM or D`Appolito design would be close to optimal.


tweet and two 6" drivers in each bookshelf?
Looking at getting 40watts per side from my Harmon Kardon

I would rather the drivers do well in the midrange than something that will smash lows.. Eventually I will buy a cheap powered woofer to ad to the computer setup and run it 2.1


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