Too complicated nipper, a 42*19 strip up each side and a single MDF panel connecting them is all I would use, cut a single decent hole in the MDF panel, called a "H" brace where the MDF part is the bar in the H
"dowels" are not nearly as effective as a holey brace. If you look at it from the top 2 holey braces (easiest if 3 pieces) would form a slightly off-centre cross.
Here is experimental data on braces. The hugher the panel resonance, the less likely the panel will resonate.
And i would rarely miss the opportunity to load the drivers push-push to take advantage of active force cancelation. Takes a huge load of the directly transmitted energy (90%?) out of the box.
dave
Here is experimental data on braces. The hugher the panel resonance, the less likely the panel will resonate.
And i would rarely miss the opportunity to load the drivers push-push to take advantage of active force cancelation. Takes a huge load of the directly transmitted energy (90%?) out of the box.
dave
You can do better than the Vifa drivers at Jaycar even though a great speaker can be made with the D25AG/P17.
I've had luck with the following in 2-ways. For a tight budget, the Peerless 830875 is a beauty and for more dollars it's hard to go past the Scan Speak 18W8531G00 as mid woofers don't get much better. For the tweeter I used the Peerless 810921 with both woofers with excellent results. This tweeter is now the Scan Speak D2608/913000.... worth every penny. Have a look at Troel's site for some design ideas using these drivers.
nipper575
Another cheap option for more bass and drive is to create a 2.5 way using the same MA6 drivers as the 0.5 woofers. All you need is around 4.7mH inductors for each side, a box about 22-25 litres tuned to around 38Hz-40Hz. The tweeter padding may have to be eased off slightly on the 2-way speaker but that's all.
Running 18VAC transformers on the LM3875 will help with the lower impedance speakers as the rails will be about 25VDC. The other option is another LM3875 running the same gain (feedback resistors) to run the 0.5 woofers.
You just have to watch running larger drivers (aka subwoofers) in smaller rooms especially with w x d almost the same dimension as it can boom.
Like this? How tall should the MDF "bar" be?
An externally hosted image should be here but it was not working when we last tested it.
Forms a slightly off centre cross, right idea?
An externally hosted image should be here but it was not working when we last tested it.
Thanks for the input rabbitz. I was thinking that I wanted to give a 2.5 way floorstander a go, not for myself but my parents. I'm enjoying my bookshelf speakers and would like to get more use out of them. The subwoofers are just another way for me to scratch an itch, another experience to learn from. Thanks for XO advice also, you answered a question that I was about to ask.
Thanks for those links, I've done a lot of reading in the meantime.
One thing I'm wondering is about bass performance. Is a sub generally going to be the simplest way of doing it or could a decent 2.5 or (possibly...) 3 way deliver enough? I'm a bit worried about building a sub and it needing to stay off because of disturbing others with huge noise.
Other than that the reference speaker seems like a great idea. I'm a bit worried the amp could blow the P-13s however since the amp looks as though it could put out 60W, even though I'll never run it near this power most likely. Also wary about doing a speaker that is design for a small room since the lounge is quite large. How do these look instead? Looking at the first design, unsure what exactly I gain by going 2.5 way like the bottom one. I also have the room to do floor standings if there is a good reason to.
Anything else I should be considering? Not looking to cut huge corners but at the same time I think my movies and PC output will be a limiting factor before buying very high quality drivers.
Looking to build one or two of the LM4780 amps depending on requirements. (Probably showing massive noob here but) What is the reasoning behind special plate amps instead of other sort of amps for subs? The more DIY I can do the better due to cheaper (probably) and more fun.
I think realistically I was aiming for $600 - $800 AU for this project. Nearly entirely TV + movies using computer as a source (PVR) in a decently large (6m x 6m) living room.
Apologies for being persistent but can I get confirmation as to whether my H brace and Holey brace illustrations look correct.
I'm not sure which I'll use yet, the Holey looks like it would be more effective, but it may be overkill for my application, it seems that it would also cost me more in material.
I'm not sure which I'll use yet, the Holey looks like it would be more effective, but it may be overkill for my application, it seems that it would also cost me more in material.
Holey brace looks good, it should extend to reach the top & bottom and make sure that they do not lie perfectly centred in the panel.
You wouldn't catch me using MDF thou.
dave
You wouldn't catch me using MDF thou.
dave
The 22-25 litres is for the 0.5 woofer section only to add to your existing speakers. For a new 2.5 way speaker, use a volume of 35-50 litres (for 2 woofers) depending on how much extension you want. A good volume would be 42 litres Fb=38Hz which will get below the magic 41Hz but 35 litres still punches below 45Hz. A 80mm min port diameter would be required.
A 4R stable amp would be required but most modern commercial SS amps handle this with ease.
There are a lot of advantages with a 2.5 way such as lower distortion and built in BSC etc. In fact my mains are a 2.5 way electrically even though they look like a 3-way with a larger 0.5 woofer than the mid woofer.
Thanks for the advice. So if I were to build a 2.5 way later on, using the same MA woofers and tweeters, all I need to do to the existing XO design is add a ~4.7mH inductor for each .5 woofer and wire them in parallel to the existing woofer, correct?
Can you explain why I may need to adjust the L-Pad for the tweeter in the 2.5 configuration? Is it to better match the tweeter's volume to the woofers, or is it something to do with the impedance seen by the amp?
Can you explain why I may need to adjust the L-Pad for the tweeter in the 2.5 configuration? Is it to better match the tweeter's volume to the woofers, or is it something to do with the impedance seen by the amp?
planet10, if I use the Holey Brace method in my enclosure, how much dampening would you recommend that I use? Should I still fill the enclosure to the brim?
You pad the tweeter down to have a good balance, if you have more bass and more midrange thee tweeter has to be louder to be in balance, this is why some builders like dialable "L-Pads"
Highrange Level Control LC 57 H' - Soundlabs Group
Loudspeaker Level Control LC 95 - Soundlabs Group
I do not think there are any more stocks of the original components left
Highrange Level Control LC 57 H' - Soundlabs Group
Loudspeaker Level Control LC 95 - Soundlabs Group
I do not think there are any more stocks of the original components left
Cheers Moondog55, those dialable L-Pads look like a good idea, even if it's just to get an idea of how much attenuation you need and then replacing with two fixed resistors.
One day I'll have to move my speakers around the room/house to see if I can hear a noticeable change in low end response. Room gain is still somewhat a mystery to me, haha.
It seemed as if the mids were a bit overpowering, at my regular listening height anyway.
The woofers have been ordered, came to ~$150 with shipping. Going to suss out the enclosure material today also.
The woofers have been ordered, came to ~$150 with shipping. Going to suss out the enclosure material today also.
I saw mention of the oaudio subwoofer amp. There was a member on stereonet that offered to order 2 and save on shipping. That was last week but you may be able to double up with him. Sorry if this has already been sorted. This thread is pretty long and I havent read through it all. 🙂
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