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]

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

 

[Moondog55]

I have another suggestion, better bass.
Get a small full range driver with an extended top end and run a cheap woofer as a .5 driver using the biggest coil you can afford, about 12mH works for me.

The coil in series with the woofer, only lets the woofer play below 120Hz and the full range plays everything.

I've done a couple of these lately , but using older scrounged 8inch drivers from old stereo boxes I find on the side of the road.

I suggest scrounging at yard sales first, only drawback is that a high value coils can be expensive.

 

[freddi]

hi planet10 - I'd say Sammi needs a helper tweeter but for me when listening (with baffle step filter) to Ivan Kozlovsky's 1956 Bach Cantatas with organ and flute, its treble extension was "sufficient".

Dave (planet10) babies, saves, massages and improves drivers - my dust bin and clutzy habits pretty well ruins them in short order

Sammi 1/6 octave in-room

An externally hosted image should be here but it was not working when we last tested it.

"Fake Druid" B102 vs B20 - - B20 is a bit more extended on top than the Sammi.

An externally hosted image should be here but it was not working when we last tested it.

B20 after a few years of laying out of cabinet

An externally hosted image should be here but it was not working when we last tested it.

 

[Moondog55]

Fostex FE83E 3" Full Range from Madisound

plus

Peerless 830657 6.5" SDS Woofer from Madisound

plus

Madisound 12.0 mHL 18 AWG Iron Core Inductor from Madisound

just a small box for the woofer with a small internal for the Fostex

 

[SnoopKatt]

I see a lot of cool cases and the like for the BOFU, but I don't see the exact XO design for them. Where could I find that?

I'm sorry if I'm asking a lot of obvious questions, I'm still really new to this concept (even though I registered almost 2 years ago here ) and I've been making an honest effort to search for everything, but I can't find anything on the XO design.
Thanks!

PS Moondog55, that looks like a great build too that I might try, but I just wanna work with cheaper components first. Thanks for posting it though

 

[freddi]

with an 8ohm tweeter, all you need for B20 (Pioneer) or Sammi is like 0.68uF->say 1uF or so capacitor on the tweeter. For Piezo its different- smaller CTS piezo tweeters are like a 0.13uF capacitor in characteristics so you've got to parallel a resistor across a piezo before the highpass cap can work. Jeff (Zillaspeaks) has used a lemon-squeezer piezo for years with B20 (or whatever model you guys call it) and info can be found on Zillaspeak pages. The dual cone 8" speaker runs fullrange - they go to ~10-11Khz on axis, have typical hole above 3K off axis and rolloff in power. Its cheap as only one small value film cap is needed plus the simplicity makes for dependability. Woofer + small fullrange on open baffle is popular too but proper passive crossover can get expensive.

here ya go : B20 + piezo on Zilla's pages http://www.zillaspeak.com/pioneerb20-piezo.asp

 

[SnoopKatt]

Hmm, that build looks good too, not too expensive.

I was poking around and I found this calculator: 2-Way Crossover Designer / Calculator

I know for the BOFU, 2.0uF is what I should use, but I'm also curious about the orders this site lists. Which one would be ideal for that one and the build freddi just listed? Will I need an inductor on the woofer?
Thanks!

 

[freddi]

I'm not sure about 2uF. In the real world with dynamic motor tweeters, the input impedance isn't a pure resistance so a simple cap (or odd order crossover) can have interaction with the tweeter'ds resonance(s) impedance peak(s) causing the actual crossover frequency to come in lower. With a resistor across the piezo tweeter, inband Z presented to the cap will be pretty close to the resistor but the darn piezos can have an acoustic peak - - Jeff will probably read your post soon and give his values for cap. I would do it "by ear" with maybe a 0.68uF and a couple of 0.22uF - I'm not much of a speaker guy. Look at the example below of that Sammi in a BK20 back loaded horn - 0.68uF almost works with the Polydax bullet tweeter.

An externally hosted image should be here but it was not working when we last tested it.

back before the engineered economic crash had been debuted, I paid $11.60 for the Sammi 8" - here it is
in that Bk20 rear horn with Selenium ST324 cheap slot tweeter vs my Klipsch Heresy I. Heresy was elevated to get to ear level so lost some bass but still Heresy was less sensitive all around.

An externally hosted image should be here but it was not working when we last tested it.

 

[planet10]

I see a lot of cool cases and the like for the BOFU, but I don't see the exact XO design for them. Where could I find that?

For the BOFU the exact XO is a 2uF cap in series with the tweeter, this rolls it in 1st order (6 dB per octave) at about 10k. The XO is this simple because it is high up, and the tweeter sensitivity pretty much matches the BOFU. Freddi, this value has been verified in the field with about a zillion builds.

dave

 

[freddi]

yeah - that figures and makes it darn easy - I wasn't one of the zillion who paid attention - btw I had some ~5K peaking with CTS KSN1005 - even a little bit with stepup xformer. 8R/100uH Zoebel driven by 1uF - that seemed to give 102-103dB 2.83vrms/1M
At some price point it might not hurt to get a Fostex and avoid a helper tweeter - to play a single driver game. I might try stock "206en" in k-coupler and will assume (?)*its the same as the old driver??? re:B20/BOFU - is there something to put on the foam surround to slow down rot and not mess up things?

 

[planet10]

I always treat the foams with drout sealer, i use a specific brand, but don't know if that is important.

dave