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Old 24th June 2009, 10:50 PM   #1
cive1em is offline cive1em  United States
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Default My first DIY project: Convert small Yamaha speakers to …

Need advice.

I have a pair of Yamaha mini speakers that came with Yamaha VS-10 receiver (or Cinemastation Entertainment System). Their dimension is 185mm in height, 125mm in width, and 120mm in depth. There are one 1/2” tweeter and a 4” woofer on these speakers with no crossover. As you can see from a review from Audioreivew.com (http://www.audioreview.com/cat/home-...2_4281crx.aspx), those speakers do not sound good at all.

I listen to classical music as well as pop music. My favorite musicians include Kiri Te Kanawa, Luciano Pavarotti, Anne-Sophie Mutter, Lang Lang, Sarah Brightman, George Winston, etc… My current speakers are a pair of 20 years-old “Celection 3”. They are wonderful speakers.

Anyway, my goal is to convert those speakers for listening mp3 from my computer/iPod. A T-Amp will be used to power those speakers. I don’t really expect this DIY project can convert my Yamaha to Celestion. I’ll be happy if I can make some improvements over the default Yamaha setup. I’d like to keep my spending under $80.

Here are my questions:

Question 1: As you can see in the attached figure, the enclosure was built with 1/2 inch MDF. Are those enclosures suitable for a DIY speaker project? Or are those enclosures good enough for my purpose?

Question 2: Should I make it a two-way system or just use a full-range driver?

Here are my thoughts on this topic. Please correct me if I am wrong. A good designed 2-way system should sound better than a full-range speaker system. But if I go with 2-way system, I will need lots of advices on tweeter/woofer combination as well as crossover design. I have no experience on building a crossover. But again, this is probably a month-long project for me. I guess I can learn how to build a crossover.

Question 3: If I go with full-range speaker design, all I need is to pick up a full-range driver. Is this true? Do I still need to have crossover?

Question 4: What driver should I get? How do I make sure the driver(s) will work with my enclosure? Is there a software/freeware for this?

Sorry for my long post. There are lots of questions on my mind right now. I know I shouldn't expect to get all my questions answered in a short time. Please point me to the right direction. Any suggestion will be greatly appreciated. Thanks.

Luke
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Old 29th June 2009, 05:19 AM   #2
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first thing to try is to put some stuffing in the existing enclosures and see if that improves the sound.

you say they have no crossover - not even a single capacitor?

The boxes may be suitable for another speaker, but the usual process is to choose the driver first and then design the box...

I'm sure the guys on the full range forum will have plenty of suggestions for a simple single driver set up
(but IMHO, even full range systems are better as 2 ways )
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Old 29th June 2009, 02:18 PM   #3
mattmcl is offline mattmcl  United States
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I can't answer all your questions, but I can tell you that 1/2" MDF is too thin. I use 3/4" even for smaller speakers.

With a full range driver you will not need a crossover.

A 2-way is not necessarily better than full range. It all depends on the design and quality of the drivers, in that order.

It sounds to me like you're considering new drivers? If so, you're probably going to be better off building a new set from scratch.
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Old 29th June 2009, 02:29 PM   #4
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Old 29th June 2009, 04:55 PM   #5
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Can you post some pictures?

1/2" MDF is commonly used for boxes this size. It is probably just good enuff to not be terrible. (personally i do not recommend MDF at all)

A 2-way does not guarantee better performance than a FR... some would say that the cross-over gives a big advantage to the FR.

Your speakers will have at least a cap on the tweeter (how big is is). In actual fact it is possible that these are really a FR already, with a tweeter added as an afterthot so they could call it a 2-way.

What i would do if i were you, would be to just make these sound as good as possible with the basic bits you already have... if you want to do a FR, just start from scratch.

1/ brace the box
2/ improve wiring, terminals (maybe) & the crossover part
3/ mod the drivers.

What you learn will be invaluable to learning how these things work, and if you go all the way, you will be quite surprised at how good these can get.

dave
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Old 29th June 2009, 08:07 PM   #6
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Pictures of the actual driver would help, as Dave says ; it may already be a full-range.
Sometimes the small XO cap is glued to the tweeter and quite easy to miss.
I think I just acquired 1 (one) of the little speakers in a box of assorted bits'n'pieces; I'll have a look and listen after breakfast.
But as Pete said, a little damping material inside the box is the first tweak I try too.
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Old 29th June 2009, 10:54 PM   #7
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Just pulled them apart, different speaker, the ones I have here are a 31/2 inch full range with a 150uF cap in front to cut some of the LF.

No tweeter just a blanked hole in the box

Just for interest sake I also pulled apart the LG plastic and the Panasonic plastic boxes.
All the drivers are similar, cheapish.
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Old 30th June 2009, 03:38 PM   #8
cive1em is offline cive1em  United States
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First of all, I’d like to thank you all for your advices and suggestions on this project.

As some of you mentioned, this is really a halfhearted DIY project. One reason is I’m not very good at woodworking, that’s why I decided to recycle my existing Yamaha speaker boxes. This is like stuffing a Toyota Corolla engine into a Honda Civic. It may run but not smoothly.

Anyway, here is what I have done for the past few days:

I went to a few websites to study information regarding speaker enclosure designs, crossover designs, driver selections, and so on. I learned how to use WinISD and UniBox to get driver responses. I read an article from Parts Express “building a crossover from scratch”
http://www.parts-express.com/project...er/xover.html. It does not seem to be very difficult to build my own crossover.

I took a close look at Zaph’s ZBM4 (http://zaphaudio.com/ZBM4.html) design. I read Zaph’s “Small Driver Comparison” (http://zaphaudio.com/smalltest/) and “Tweeter Mishmash” (http://zaphaudio.com/tweetermishmash/). I also went to a few online stores to check on specifications of tweeters and small drivers.

After some research, I decided to purchase two Aura NS4-255-8F-SP full-range drivers from Madisound. They are on sale for $14.95 each.

Why did I get Aura NS4?
1. It was Zaph’s comment on Aura NS3 caught my eyes - “An exceptionally wide bandwidth driver, with smooth response. This is one of the very few drivers that "could" be run full range without a filter, though I'd still recommend at least a little baffle step compensation. If you choose to use a tweeter, you can cross over as high as 4kHz, with the only limiting issue being vertical lobing due to driver spacing. Minus one star in build quality for a stamped steel frame that is flimsy.” Since I’m not sure if I can really build a crossover from scratch, it may be better to go with a full-range driver model without crossover. I also made an assumption that Aura NS4-255 should perform similar to Aura NS3.
2. According to its specification, Aura NS4 fits to the hole on my Yamaha Speaker enclosure.
3. If I don’t like the results, I can start a new DIY project later.
4. They are cheap ($14.95 each).


I received NS4 yesterday. I installed them to Yamaha enclosures and also made following modifications on those boxes.
1. There were no speaker terminals on the boxes. I drilled two holes and put in RadioShack “Chassis-Mount Dual Female Binding Post” (http://www.radioshack.com/product/in...ductId=2102838).
2. I bought couple feet of 16-gauge oxygen-free speaker wire and disconnects. I used them to connect NS4 drivers and binding posts.
3. I left the original tweeters on the boxes just to seal the tweeter holes. I call those Passive Tweeters 
4. Aura NS4 fits perfectly on the driver hole.


I hooked both speakers on my 20-years-old Onkyo receiver.

I put in Sarah Brightman’s “Time to Say Goodbye”. I was a little disappointed on the music at first. It sounds OK but not great. It’s definitely better than the factory default setup but not quite up to Celestion 3.

The second album is George Winston’s December. Again, it sounds just OK. My 20-years old Celestion 3 sounds a lot better.

The third album is a Burgmuller’s 25 Progressive Pieces, Op. 100. This is an instruction CD for my daughter’s piano class. I was thinking about to give these speakers to my daughter. I didn’t put a lot of hope on it. I was surprise to find it actually sounds pretty good.

I started to play more classical piano music. They sound very decent. My wife and I also listened to a few Mozart’s flute concertos. They are very nice. Well, not as nice as Celestion 3. But again, nothing compares to Celestion 3.


I am fairly happy with this pair of speakers so far. Here are a few things I would like to work on them later.
1. There is no damping material right now. I will need to get some.
2. Make crossover. I would like to design and build crossover myself.
3. Find a matched tweeter. I can make it a two-way system.


Again, thanks for your advices. Attached are few photos.
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Old 30th June 2009, 03:57 PM   #9
mattmcl is offline mattmcl  United States
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What specifically did you not like about the sound? The answer would go a long way to helping you figure out the best solution.
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Old 9th July 2009, 03:36 PM   #10
cive1em is offline cive1em  United States
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Just came back from my summer vacation. Here are some updates on my project.

1. Just found out I misread "vent length" parameter on WinISD by a digital. It is 65 cm not 6.5 cm. There's no way to put a 65cm vent in my Yamaha speaker enclosure. That maybe the reason my speakers sound good on some music and bad on other music. So I rerun WinISD with a closed-box setting. The simulated result looks good to me. So I sealed their vents to make them close-box speakers. I will get some damping material later.

2. I also bought a HLLY TAMP-10 (with Tripath TA2024) on eBay.

I connected all components (T-AMP, iPod Video, speakers) together last night and listened some classical music. I think they sound a little better than before. But again, maybe the improvement is because of T-AMP. Anyway, I'm happy now.

One thing with T-Amp is I have to turn both volume controls on T-Amp and my iPod Video all the way up. This setup is only good for a small room.

It's been a fun DIY project so far. Thanks for all your advices.

Luke
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