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Old 26th July 2012, 02:54 AM   #1
secondo is offline secondo  United States
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Default tear down 2k bookshelves or build from scratch?

I want to build a very nice set of bookshelf speakers. I was planning to buy high end components and had access to them at a reasonable price through an audio dealer/friend. he could get me tweeters and drivers from brands he sells for very reasonable prices (ie less than 1k for components to speakers 5-10 times that) although they might not perfectly match in the sense that the brand of the tweeter might be different from the brand of the woofer and I might be on my own building crossovers, finding binding posts, etc. He'd help me pick components that at least in theory would play well together.

I am a fairly experienced wood worker (I make mortise and tennon furniture for a hobby)

I also was recently offered a damaged pair of highly reviewed $1500 speakers that a friend has. the components are in good shape, but the boxes were damaged. He'd part with them for half price.

The beauty of this approach is that I would just have to build a box and all the components would match, the size could be dictated by the original so I'd know the crossover would be a good match, etc.

So here is the question I am pondering - which will be likely to sound better: the reconstructed speakers or a pair of speakers with even higher end components, but where I have to try to guess the right size/ shape of the box, the crossover, etc?

A few last comments, I can do the math if necessary - that is not a problem, but my ear is less good than my math skills so while I am fine at finding things I like musically, I am not as good at recognizing why something doesn't sound perfect to me. Also I've read a little about speaker building, but I've never done it before.

Any advice is welcome.
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Old 26th July 2012, 03:02 AM   #2
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I would advise that, unless you have a lot of experience designing crossovers, that you get the damaged pair and build a new set of cabinets for them.

There seems to be two sets of camps in the DIY loudspeaker genre:
  • Those who come from the engineering side of the equation who can design great sounding speaker but who can't build a physical speaker box that is drop dead gorgeous
  • Those who come from the woodworking side of the coin, who have a garage or shop full of tools, a vacuum veneer press, paint booth, etc. at their disposal and who can turn out stunning but often flawed sounding speakers due to their lack of knowledge in the area of crossover design and acoustics.
I sure wish that I could team up with someone from the "other side". Can you guess which "side" I am on?

Anyway, don't forget that a speaker box should not be built from hardwood like fine furniture. Damping of the walls/baffles and adsorption material is critical so that you do not have an acoustically transparent "box". Lossy materials like particleboard are actually advantageous in some ways. Just don't use them on the "outside".

-Charlie
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Old 26th July 2012, 03:16 AM   #3
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Option 3 - Build something designed by an established DIY designer. I would recommend looking into Jeff bagby's Piccolo, Curt Campbell's Invictus, and Wolf's Demeanors, to name just a few.

What you'll find is that it's more than just "math" It's not a circuit you're making, it's a transducer that will be interacting with the room. It's thus not 2 dimensional.

The other thing you'll find is that yes drivers matter, but it isn't just a matter of picking really good ones and hoping they mesh. A good system design depends on different aspects of the driver selection, - not just how much they cost. Often 1k in drivers will be outperformed by a few hundred simply by virtue of place-of-manufacture (IE SB acoustics is made in indonesia whereas Scanspeak is made in Denmark), driver off-axis response (a 3-way using a 70 dollar 2" mid may work better than a 2-way using a 6.5" midwoofer), and final crossover quality.

I'm not sure what drivers are used in that $1500 damages speaker. It would help if you would let us know.

Likewise, the parts your dealer friend is helping you acquire may not be all that great.
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Old 26th July 2012, 03:54 AM   #4
secondo is offline secondo  United States
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Good point. The damaged speakers are Dynaudio Excites. I think they are the x sixteens, but could be the x twelves.

Of the camps mentioned above, I fall into the woodworker (hobby), non-engineer camp, but I do math for a living, so I feel like I could learn many aspects of the engineering although I don't know it yet.
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Old 26th July 2012, 04:26 AM   #5
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hehe I fell into neither camp, but decided to jump in anyway. The end result has thankfully been a success. However be warned that there is a LOT to learn to get to the point where you can pull it off. For me (and this is not indicative) I started to think about the speakers in 2003 and the final finished product was not until around this time last year!

There were some pretty big gaps where there was no activity but there was a lot of time spend reading, simulating prototyping, measuring and building as well (there was about a 4 year period where I did nothing at all).

I went down the measurement and simulation road, but just getting to the point where I could get reliable measurements in itself was hard. I had around 16 years of "experimenting" with different off the shelf crossovers and drivers in my three way speakers before embarking on this project so I knew a lot about how *not* to do things

In my oppinion a few "simple" but crucial points need to be comprehended before success can be achieved.

1. Don't worry about the electrical order of the slopes, it is the accoustic slope that matters, the electrical is the means to the end.

2. Get an understanding of phase and why you want your drivers in phase around crossover. learn how to tweak your crossover to achieve this (time aligned drivers will help a lot here).

3. Understand that baffle geometry and driver placement do have an effect due to diffraction, simulation here helps to find a good compromise.

There are many other aspects as well, but I think the above were probably the main impediments for me until I grasped them.

Tony.
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Old 26th July 2012, 02:46 PM   #6
DrDyna is offline DrDyna  United States
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+1 rebuild the Dyns.
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Old 26th July 2012, 03:34 PM   #7
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It seems you can easily rebuild the dyns or, 'assemble' the elegant, bookshelf size Intimates. Design and construction details here. The ones I build used pre-fab'd Cherry finish 1/2 cu. ft. cabinets. WAF factor is VERY high.

Introducing the "INTIMATES" (high WAF & quality sound)
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Old 26th July 2012, 06:25 PM   #8
sreten is offline sreten  United Kingdom
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Quote:
Originally Posted by secondo View Post

I also was recently offered a damaged pair of highly reviewed $1500
speakers that a friend has. the components are in good shape, but
the boxes were damaged. He'd part with them for half price.

Any advice is welcome.
Hi,

I bet he would. Small expensive speakers typically go for about
half new price used in perfect condition, damaged much less.

Dynaudio Excite X12 loudspeaker | Stereophile.com

Click the image to open in full size.

Quite nice little speaker if you want a little speaker. I don't know how
the boxes are damaged, but are likely very well built and probably it
would be most effective to refinish them than start from scratch.

The 16's are somewhat bigger :

Click the image to open in full size.

There are plenty of very well documented and very good designs
available, where all the tricky acoustic design has been done, and
they only need good cabinets.

If you can get good drivers cheap, e.g. Vifa , Scanspeak etc
then you won't be on your own regarding the crossover e.g. :

Zaph|Audio - ZD5 - Scan Speak 15W8530K00 and Vifa XT25

It depends on what sort of speakers you really want.

Checkout :

Humble Homemade Hifi and
DIY Loudspeaker Projects Troels Gravesen

For the more ambitious approaches to building quality boxes.


rgds, sreten.

http://sites.google.com/site/undefinition/diy (see if nothing else, the excellent FAQs)
The Speaker Building Bible
Zaph|Audio
Zaph|Audio - ZA5 Speaker Designs with ZA14W08 woofer and Vifa DQ25SC16-04 tweeter
http://audio.claub.net/Simple%20Loud...ign%20ver2.pdf
FRD Consortium tools guide
Designing Crossovers with Software Only
RJB Audio Projects
Jay's DIY Loudspeaker Projects
Speaker Design Works
HTGuide Forum - A Guide to HTguide.com Completed Speaker Designs.
A Speaker project
Quarter Wavelength Loudspeaker Design
The Frugal-Horns Site -- High Performance, Low Cost DIY Horn Designs
Linkwitz Lab - Loudspeaker Design
Music and Design

Great free SPICE Emulator : SPICE-Based Analog Simulation Program - TINA-TI - TI Software Folder
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Old 26th July 2012, 06:40 PM   #9
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Quote:
Originally Posted by sreten View Post
Hi,

I bet he would. Small expensive speakers typically go for about
half new price used in perfect condition, damaged much less.
Add to that the consideration that the rule of thumb for retail speakers sold in bricks & mortar stores, then a $2k speaker has approx $200 worth of drivers in it.

dave
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Old 26th July 2012, 10:28 PM   #10
sreten is offline sreten  United Kingdom
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Quote:
Originally Posted by planet10 View Post
Add to that the consideration that the rule of thumb for
retail speakers sold in bricks & mortar stores, then a
$2k speaker has approx $200 worth of drivers in it.

dave
Hi,

For some makes that is probably true, not that you'll
be able to buy them for $200 as spare parts usually.

For around $400 in parts you could build either of these :

Zaph|Audio - ZDT3.5
Parts Express DIY Project

Click the image to open in full size.

or

https://sites.google.com/site/undefinition/tarkus

Click the image to open in full size.

or bit more :

https://sites.google.com/site/undefi...diy-sunflowers

Click the image to open in full size.

They would retail for serious money, especially if you do a really good
/ nice job on the cabinets, some mechanical engineering skill is needed
to build very performing cabinets, as opposed to just looking nice.

Performance wise miniatures are not in the same ballpark.

rgds, sreten.
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Last edited by sreten; 26th July 2012 at 10:36 PM.
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