First Time Builder, Building a Cheap Speaker

[SnoopKatt]

Hello,
Over spring break, I figured it'd be a good project to do with my dad to build a speaker. I eventually want to build a nicer speaker, but for now, I just want to build a cheap 3-way speaker, so in case if I wreck something, it won't hit my wallet too hard. I'm capable of soldering and various woodwork. Here's what I've picked out:

Tweeter:
Goldwood GT-25 3.5" Paper Cone Tweeter from Madisound

Mid:
Goldwood GM-65/8 5" Midrange from Madisound

Woofer:
Goldwood GW-204/8S 4" Shielded woofer - 8 ohm from Madisound

I made sure they were all 8ohm. I know it'll probably sound terrible though

Here's where I'm stuck: I have no idea what to do for the crossover. What would be a good place to start with that, and how do you figure out a proper crossover configuration?

And just to double check, 3/4" MDF would probably be prudent for the enclosure, right?

Thanks for any help!

[planet10]

1st off, your bass driver is very likely a better midrange than the midrange you've chosen.

Crossovers are the really hard part of building a multiway...

Let's look at this, $42 budgeted for drivers, you'd probably need to spend close to that on crossover parts.

You would be WAY further ahead with a simple 2-way or even a 1-way.

The commonly recommended goto budget 2 way is based on the Pioneer BOFU
Pioneer B20FU20-51FW 8"
Dayton ND16FA-6 5/8" Dome Tweeter
Dayton PMPC-2.0 2.0uF Capacitor

It fits within your budget if you can afford my estimate of the XO parts cost.

The Goldwood woofer you have choosen with the tweeter (and XO) from the BOFU system would be better than what you've choosen.

My penchant is 1-way systems, here is a laundry list of cheap ones... any of them would be more satisfying than your 3-way (althou the 3" won't provide as much bottom), some of the bigger ones might benefit from a super-tweeter,

Pioneer A11EC80-02F 4-1/2"
Tang Band W4-656SC 4"
Aura/Dayton Audio ND105-4 4"
HiVi B4N 4"
HiVi B3N 3"
HiVi B3S 3"
Tang Band W3-319SF 3"
Tang Band W3-593SF 3"

I've only had direct experience with a variation of the last one, given your budget i'd likely look at doing something with 2 per side of the 3" HiVi, with plans for a sub as a next project.

If you want more bottom out of the gate, one of the 4". The Aura/Dayton + the bofu tweeter (you'll likely need to pad the tweeter (which changes the cap size you need), probably gives the most performance, but the HiVi is sure sexy looking.

If the budget stretches to the BOFU system 1st mentioned i'd actually spend it on a pair of Mark Audio CHR-70

dave

PS; i'd use 1/2 or 5/8" plywood.

[srinath]

For a low budget speaker build - no better option than this.
Craigslist a couple of no distinction ones that have decently thick cabinets. Fisher ST series was my choice. Then buy drivers to fit it.
Option 2 is to go to pull a part and grab a whole lot of door speakers out of cars. My local one would sell you a speaker for 2.99, and they cap you off at 3-4. Like take 4, take 25 same $ ... get some door, some rear ones out of a panel van, rear out of cars and SUV's also were big ... dash ones were smaller ...
Dash is dual cone usually, door and rear singles ... put em all in a cabinet you make for em.
Advantage here is - chrysler, mitsu, hyundai, kia and some others used infinity.
GM, nissan, toyota some other ones used bose if I remmeber.
Some others had JBL etc ... Just not their high end stuff. But better than usual car crap.
Then of course make a cross over and put them on the cabinet.
Cool.
Srinath.

[freddi]

there's a competent Sammi 8" wideband surplus speaker - its durable (I've hit brief >100W maybe 200w peaks into one - I probably got more than 115dB out of one in a Karlson toy), has good qts for vented systems, sturdy basket, $19.95 (not including shipping) has a cloth surround, vented polepiece and one could augment it with a cheap tweeter with just a highpass capacitor of maybe 1uF or so to kick in around 7Khz on axis. I've run one in a BK20 backloaded horn and had ~8dB more sensitivity than a Heresy. Stock its not the last word in transparency, and its coil is pretty large. B20's foam rotted in my environment within 5 years.

rear view - (pic too large) Sammi next to a BetsyK
http://img52.imageshack.us/img52/8686/sammibetsyk.jpg

High Quality Raw Frame 8" Loudspeakers - 50 Watt - NEW - eBay (item 390109337367 end time Apr-20-10 21:28:25 PDT)

[SnoopKatt]

Thanks for the quick responses guys!

Hm, yeah a two way is simpler, and I guess when I do a real build, I'd probably just end up doing that instead, so yeah, I'd be happy to build a 2-way demo. So the Pioneer BOFU w/ the Goldwood woofer is what you'd recommend?

I saw that one of the woofers you recommended (Parts-Express.comayton ND105-4 4" Aluminum Cone Midbass Driver 4 Ohm | Dayton Audio ND105-4 Aluminum Cone 4" driver Full Range Driver mid bass extended range line array monitor point source aura Neo-Sym) goes a bit deeper than the Goldwood and it's only $3 more, which I'd be willing to spend. Would that work with the crossovers from the BOFU?

Great idea for the cabinets srinath!

freddi, sounds like it'll be a great woofer, but right now I'm just trying to build a minimum speaker just to get experience with building them. I want to build a system that sounds good eventually, but I don't want to ruin any good components, so I just want to build something very basic, even if the components aren't anywhere close to audiophile grade.

[planet10]

The BOFU with the Dayton Tweeter... (you could probably sub in the Sammi Freddi mentioned). The Aura/Dayton would likely need a different XO, the tweeter would need to be padded down with a resistor to match levels which would mean a smaller cap.

I wouldn't use the Goldwood tweeter at all for anything.

dave

[freddi]

lol - its a fullrange, its got enough motor where it doesn't need a big box - fwiw I like the Sammi somewhat better overall than B20 - here's one at a distance then walking close - it could play maybe 6-8dB louder w/o burnout depending upon average power in music - I didn't have enough gain that day to drive the power amp loud - besides mic overload the Karlson "klam projector" did make some weird echoes up close - I think I could do a pretty big party event with just one - if the coil doesn't catch fire
I might buy a few more but have 4 extra in my driver stash. Your Dad might like B20

YouTube - karlson projector speaker

[SnoopKatt]

Yeah I'd prefer to not have to pad too much down with resistors or anything.

So that one capacitor you listed would be enough for the crossover?

[planet10]

I wouldn't be surprised Freddi... i had a system built-up with B20 but scored some budget ($20/pr and more colourful) that i subbed in when i had the opportunity to sell the B20 for a profit. With a bit of work i was able to make them sound better and not need a tweeter (phase plugs, cone treatment and a parallel LCR in series... gave them to my godson, one of these days we'll EnABL them.

dave

[planet10]

Originally Posted by SnoopKatt

So that one capacitor you listed would be enough for the crossover?

For the Pioneer (I take it Freddi says you could get away without tweeter with the sammi).

If you do a search on BOFU or Pioneer B20 you will find a lot of info about successful builds for these.

dave