Kit in Australia

[Francec]

"Made in China, surely there is a vendor that will save having them shipped back across the Pacific."
dave, that is the mistake many septics and their neighbours make about Australia. It has a very small population for its geographical size so many products don't come here and, if the do, many are expensive.

nipper,
"Maybe a LM4780 based amp is on the cards... ". I would be inclined to use a LM4780 and run each amp into a single driver. Half of the energy in music is below 300Hz so don't underpower from the beginning which will cost more in the longer run.

Mark Knoeplfler "Sailing to Philadelphia" is on at the moment. Great album!

Frank

 

[Moondog55]

I agree the equal distribution point is around 375 Hz but how much actual music is there below 80? Not much but what is there is important. 50 watts is plenty if it is into 2 separate boxes, I have over 400 available but I have never used more than 20 or 30 watts for most music bass peaks and usually around 2 to 5 watts.
Mind you there is nothing wrong with having power and too much power is just the starting point

 

[planet10]

....Australia. It has a very small population for its geographical size

Not all that different than Canada. Australia ~2.93 people/km^2, Canada 3.44

we do have the US next to us, but you have Hong Kong.

dave

 

[Moondog55]

Postage or DHL from HK aint cheap

 

[nipper575]

The Jaycar drivers do tend to be a little inconsistent is the only problem but that is a good price and available in Tassie I think.
Using two boxes gives you lots of options, even putting them together under a desk or cabinet or in corners, a lot will depend on how low they are cut in and the XO slopes.
If you do go ahead you may find that closed boxes, which have a natural 2nd order roll-off integrate better, are a better option.
in that case you just block your ports with a sock or two or a foam plug

I assumed they wouldn't be of the highest quality, but that doesn't bother me too much at this point. We have Jaycar in Tassie but even if they don't stock the drivers, shipping is very cheap.

I'll keep the port blocking in mind, I was planing on a ported design unless I can be convinced otherwise.

I used 225VA

Is that custom made? The closest I can find around that spec would be 160VA or 300VA.

Made in China, surely there is a vendor that will save having them shipped back across the Pacific.

Haha, seems ridiculous, doesn't it. I've done a quick google search with no success. I'll keep looking.

Getting on to box design. I was thinking of something with a small footprint, skinny and tall rather than stocky and short. You both seem to favour this push-push style configuration which from what I've seen means you have the woofer magnets wedged against each other. I have read a quick explanation by planet10 on another thread, I'm happy to give it a go.

I'm guessing that the woofers that planet10 posted earlier are a push-push configuration. With that sort of setup, woofers firing left-right, how much space do I need on either side of the box if I were to use a similar design?

 

[nipper575]

nipper,
"Maybe a LM4780 based amp is on the cards... ". I would be inclined to use a LM4780 and run each amp into a single driver. Half of the energy in music is below 300Hz so don't underpower from the beginning which will cost more in the longer run.
Frank

Something I'll definitely consider, I've been itching to build a LM4780 ever since I completed my LM3875.

 

[Moondog55]

Your computer sound card? Does it have sub out socket? and if it does have you a sound-card with software that will allow you to dial in the LF cut-off point and LF boost??
If it does then go with a sealed box, smaller and will handle the bass boost better
All you would need then is a cheap stereo amp that can handle 4R ( that is almost anything these days ) Craigs list ??

If you are going with an 80 Hz cut-off then both woofers facing forward would be OK and easier to implement

 

[mattcalf]

Hope all is well rabbitz!
Just wanted to chime in and let everyone know that my speakers are going well and I'm looking to get a better amp for them. Also that I find it amazing this thread is still going.

Thanks to rabbitz and moondog and the rest of you for helping everyone out.

 

[Moondog55]

G'Day Matt

Nice to see you back on thread Matt, how did your build turn out??

I had my own health problems and associated money woes so didn't get a chance to buy the drivers,

 

[nipper575]

Your computer sound card? Does it have sub out socket? and if it does have you a sound-card with software that will allow you to dial in the LF cut-off point and LF boost??
If it does then go with a sealed box, smaller and will handle the bass boost better
All you would need then is a cheap stereo amp that can handle 4R ( that is almost anything these days ) Craigs list ??

If you are going with an 80 Hz cut-off then both woofers facing forward would be OK and easier to implement

It does have a sub out socket (scroll down to audio). Sorry, I don't know what LF stands for (Low-pass Filter?). I'll have to have a look at the software to see how flexible it is, otherwise I can justify a new soundcard which I've been meaning to buy at some stage anyway. Would this mean that I do not have to build a passive XO at all?

I read you loud and clear about the cheap 2nd hand stereo amp, I am just entertaining the idea of building another amp as it is a fun project.

I must admit that I would prefer to have both woofers facing forward as I would love seeing 4 x 8" woofers staring back at me. I'm not sure what cut-off frequency to use yet, I'm open to suggestions. 80Hz seems like a good number as my bookshelf speakers should be easily capable from that range onwards.

 

[mattcalf]

My build is not the best looking set out, but sounds amazing even with the $20 t-amp currently powering them. Looking at a professional amp for xmas, as I don't currently have the time for a full DIY build.

Sorry to hear about your health, hope all is getting better.

 

[Moondog55]

Should be able to set-up for an 80Hz cut-off, that's 3 generations newer than my sound-card and mine can do it. just use a Y-cable to split into 2 streams for input into a stereo amp if needed

 

[nipper575]

That's good news, I'll start doing up some preliminary box designs and post them up here. I don't know a lot about bracing, so I'll see what I can find.

 

[planet10]

Postage or DHL from HK aint cheap

I can only guess at the weight of the Silver Flute, but based on that guess, a pair, surface post from HK would be $16 AUD (website quote) -- less than it would cost for me to ship a pair across Canada.

dave

 

[planet10]

s that custom made?

Maybe. I bought 14 of them surplus (real cheap & plitrons to boot)

I'm guessing that the woofers that planet10 posted earlier are a push-push configuration. With that sort of setup, woofers firing left-right, how much space do I need on either side of the box if I were to use a similar design?

They are... probably 6" either side.

dave

 

[nipper575]

If I only need 6" on either side, then they are a possible solution also. What volume are your sub enclosures? They don't look too big, are they sealed or ported? I keep reading that for a subwoofer, designing a ported enclosure usually results in a larger enclosure than a sealed, but with lower F3 response. I don't suppose you have a rough diagram of the enclosure that I could poach?

Under my circumstances, would people recommend that I build an enclosure with both drivers mounted at the front (which I prefer visually) or that I build a push-push enclosure?

Moondog, you suggested that forward facing would be easier to implement, is this based purely on room, are they considerably harder to build enclosures for (though I can't imagine why), or is there a far more complex reason.

 

[Moondog55]

Moondog, you suggested that forward facing would be easier to implement, is this based purely on room, are they considerably harder to build enclosures for (though I can't imagine why), or is there a far more complex reason.

It is because you only have to work with a pair of simple boxes and two baffles, not a technical issue except for placement

 

[nipper575]

Fair enough. How close should I be placing each woofer in relation to each other on the baffle, as close as possible? I'm guessing these are both to be placed close to the ground.

Here is a bit of mucking around I did on winISD, I'm really not confident with this software though.

These are the parameters I used for the Jaycar woofer. May of entered some wrong based on different units of measurement.

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

These are some quick plots. Each box has two drivers. If I have entered the parameters correctly, which one of those volumes would be best? I've read that in a sealed enclosure, a Qtc of .7 - 1 is considered better for tight bass. As I'll be using these subs mostly for enhancing movies, I'm not sure whether the requirements change. It just seems that the F3 is so high, I thought it would be lower for enclosures of this size.

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

 

[planet10]

The FonkenWoof are TLs, but next time they'll be sealed -- 2 SDX7 per box. Box is ~28 litres,

BTW, the dual #6 ML-TLs i've built are not at all bass-shy -- not sub territory, but as deep as the FonkenWoof. So another option is to just start over, doing a set of floorstanders for your existing kit (or get another set and assign the little ones to surrounds)

dave

 

[nipper575]

They look nice. I'm going to build some floor standers for my parents and those look the part. I'm sure they aren't shy of bass, even my little speakers surprised me. Did you settle on a crossover, I recall reading that you had an external XO for it. That would use a 3 way XO, wouldn't it? Also, are those little dash marks on the cone a cosmetic thing, or sonic?

For me, I'm really hooked on the idea of sub woofers now so I'd prefer to build them. Any advice in regards to the winISD plots I posted previously? It just doesn't look right to me.

Cheers