So, here are the drivers, PR, Tweeters, and XOvers I'm planning on using.
With the 2x100w Class-T Amp from Sure, or something similar. 2x12v 2AH SLAs to make 24v. Then an Instapark Charger/Controller.
I want them in this case (I've used it before with some Pioneer D1302R which sounds amazing to me).
I realize the enclosure is not ideal space. But I'm wondering if the PR will be beneficial at all. Also, those Peerless woofers mixed with the Dayton Tweeters, and the Dayton XOver at 3500k. Calculations do NOTHING for me and I can't make sense of the graphs. I'm more designer than engineer, and I assume it shows.
I am obsessed with modeling drivers and enclosures. Just trying to find the best sounding portable system I can.
I'm still learning, but building a lot and really enjoying it. Any info would be super appreciated.
With the 2x100w Class-T Amp from Sure, or something similar. 2x12v 2AH SLAs to make 24v. Then an Instapark Charger/Controller.
I want them in this case (I've used it before with some Pioneer D1302R which sounds amazing to me).
I realize the enclosure is not ideal space. But I'm wondering if the PR will be beneficial at all. Also, those Peerless woofers mixed with the Dayton Tweeters, and the Dayton XOver at 3500k. Calculations do NOTHING for me and I can't make sense of the graphs. I'm more designer than engineer, and I assume it shows.
I am obsessed with modeling drivers and enclosures. Just trying to find the best sounding portable system I can.
I'm still learning, but building a lot and really enjoying it. Any info would be super appreciated.
Nothing wrong with being obsessed with modeling drivers and enclosures, but without building and measuring, all you have are models, not "best sound".
Your parts count adds up to more than professionally designed mini studio monitors cost (that would fit in the toolbox you have decided on) which would likely sound better than the combination of parts and generic (ie wrong for every combination) crossover you chose.
Integration of parts to make something that works well involves more than picking stuff out of a catalog and hoping it works well together.
That said, I have always learned more from my mistakes than successes, so don't let my advice hold you back!
Art
The passive radiators are much too small for your woofers: you'd usually look to take your woofer size, and go a size or two up for the passives. Remember they're part of a resonant system, so PR displacement can get quite large: those woofers would stand a fair chance of turning the PRs inside-out.
Next up, I'd be hesitant to use that amplifier on batteries. They're power hungry, which means you're carrying more batteries, which makes it heavier.
For similar money, I went a different way. I'd be happy for you to borrow as much or as little from my, er, "design" as you like.
I got a pair of 12v Tripath boards off eBay, about £5 each, 15w/ch @8ohm, 25w/ch @4ohm.
I used a pair of 8" dual-coil MCM woofers. They're 8ohm per coil, so the coils went in parallel to give 4ohm to each channel of one of the amps. I then got a pair of little KEF eggs. The 3" coaxial ones with aluminium cones. Whipped the drivers out, and they're 4ohm too. Perfect.
The KEFs went to the remaining amplifier board.
Next up, using my laptop (I had planned on transferring to a PCB, but it never happened), I implemented an active crossover, LR4 (may as well go steep), 600Hz. I also cut off below ~45Hz (cabinet was 22L tuned 49Hz for the pair of woofers).
Here's the clever bit: because each amplifier is only covering approximately half the musical content, you get a nice bit of power scaling. The long and short of it is that a pair of 100w amps each covering half the frequency range will have the same available voltage swing as a 400w amp. So now the boombox sounds much louder than the rather miniscule power ratings might suggest: here we're running a pair of 25w amps per side, but that's the same as running a 100w amp per side and with passive crossovers**. I also managed to avoid using resistors to pad down either driver to get a balanced sound - that's all done in my laptop. Resistors turn electricity into heat, which is very bad when we're going portable: we need to squeeze every last drop out of those batteries.
I mentioned earlier that I put a pair of 8"ers in a 22L cabinet. Seems a bit small, right?
For ordinary HiFi listening, you'd be right. The simulated response has a large rise from 60-120Hz. This, however, is advantageous for outdoor use. Instead of using a big box to gain efficiency at LF, we throw that away and gain several dB at frequencies where you're gonna hear (and feel) it: a pair of 8"s trying to do 35Hz outdoors is basically pointless. Make 60Hz much louder - there's much more musical content there, so lets make the most of that.
In-room, the sound is "hefty" or "boomy". Whichever. It can be eq'd out, but I drag this out for parties occasionally, so the low end is welcome.
The shape of the low-end response was advised by Saturnus, over on the Boominator thread. I believe the Boominator itself has an even more severe peak than my design, but that uses 4x10" PA woofers, so probably a bit bigger than you'd want to build.
I've had comments like "hey, that sounds better than my stereo at home...", and "can you turn it down, please?"
It'll also throw the sound (loud and clear) to around 50m at full tilt, but it is rather loud when right next to it at that point.
HTH
Chris
** you can also really push it and clip the bass amp, but, so long as the mid-high amp doesn't clip, it'll still sound pretty reasonable. I've never run out of power, though, even when being silly.
Next up, I'd be hesitant to use that amplifier on batteries. They're power hungry, which means you're carrying more batteries, which makes it heavier.
For similar money, I went a different way. I'd be happy for you to borrow as much or as little from my, er, "design" as you like.
I got a pair of 12v Tripath boards off eBay, about £5 each, 15w/ch @8ohm, 25w/ch @4ohm.
I used a pair of 8" dual-coil MCM woofers. They're 8ohm per coil, so the coils went in parallel to give 4ohm to each channel of one of the amps. I then got a pair of little KEF eggs. The 3" coaxial ones with aluminium cones. Whipped the drivers out, and they're 4ohm too. Perfect.
The KEFs went to the remaining amplifier board.
Next up, using my laptop (I had planned on transferring to a PCB, but it never happened), I implemented an active crossover, LR4 (may as well go steep), 600Hz. I also cut off below ~45Hz (cabinet was 22L tuned 49Hz for the pair of woofers).
Here's the clever bit: because each amplifier is only covering approximately half the musical content, you get a nice bit of power scaling. The long and short of it is that a pair of 100w amps each covering half the frequency range will have the same available voltage swing as a 400w amp. So now the boombox sounds much louder than the rather miniscule power ratings might suggest: here we're running a pair of 25w amps per side, but that's the same as running a 100w amp per side and with passive crossovers**. I also managed to avoid using resistors to pad down either driver to get a balanced sound - that's all done in my laptop. Resistors turn electricity into heat, which is very bad when we're going portable: we need to squeeze every last drop out of those batteries.
I mentioned earlier that I put a pair of 8"ers in a 22L cabinet. Seems a bit small, right?
For ordinary HiFi listening, you'd be right. The simulated response has a large rise from 60-120Hz. This, however, is advantageous for outdoor use. Instead of using a big box to gain efficiency at LF, we throw that away and gain several dB at frequencies where you're gonna hear (and feel) it: a pair of 8"s trying to do 35Hz outdoors is basically pointless. Make 60Hz much louder - there's much more musical content there, so lets make the most of that.
In-room, the sound is "hefty" or "boomy". Whichever. It can be eq'd out, but I drag this out for parties occasionally, so the low end is welcome.
The shape of the low-end response was advised by Saturnus, over on the Boominator thread. I believe the Boominator itself has an even more severe peak than my design, but that uses 4x10" PA woofers, so probably a bit bigger than you'd want to build.
I've had comments like "hey, that sounds better than my stereo at home...", and "can you turn it down, please?"
It'll also throw the sound (loud and clear) to around 50m at full tilt, but it is rather loud when right next to it at that point.
HTH
Chris
** you can also really push it and clip the bass amp, but, so long as the mid-high amp doesn't clip, it'll still sound pretty reasonable. I've never run out of power, though, even when being silly.
That's correct.
Actually, Chris and Art have done a good job splainin'
Agreed. They have helped out a ton.
Passive Radiator = Reflex Port Subtitute
The Passive Radiator should be capable of displacing twice the volume (Vd = Sd * Xmax) of its companion woofer driver.
Recommend you study the following articles:
AES E-Library Passive-Radiator Loudspeaker Systems Part 1: Analysis
http://www.aes.org/e-lib/browse.cfm?elib=2731
If you want a copies let me know.
Regards,
WHG
So, here are the drivers, PR, Tweeters, and XOvers I'm planning on using.
With the 2x100w Class-T Amp from Sure, or something similar. 2x12v 2AH SLAs to make 24v. Then an Instapark Charger/Controller.
I want them in this case (I've used it before with some Pioneer D1302R which sounds amazing to me).
I realize the enclosure is not ideal space. But I'm wondering if the PR will be beneficial at all. Also, those Peerless woofers mixed with the Dayton Tweeters, and the Dayton XOver at 3500k. Calculations do NOTHING for me and I can't make sense of the graphs. I'm more designer than engineer, and I assume it shows.
I am obsessed with modeling drivers and enclosures. Just trying to find the best sounding portable system I can.
I'm still learning, but building a lot and really enjoying it. Any info would be super appreciated.
The Passive Radiator should be capable of displacing twice the volume (Vd = Sd * Xmax) of its companion woofer driver.
Recommend you study the following articles:
AES E-Library Passive-Radiator Loudspeaker Systems Part 1: Analysis
http://www.aes.org/e-lib/browse.cfm?elib=2731
If you want a copies let me know.
Regards,
WHG
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I know it was a rather long post, but do you have any questions?
I'm happy to help where I can - its a really good feeling when people come over to say hi and enjoy the music.
Also, there's not much need for passive radiators for outdoors (unless you want a waterproof enclosure), as the ports end up quite small because of the relatively high tuning. This also keeps air velocity down: my woofers have a couple of bits of 40mm pipe for ports. About 11cm long each, IIRC. No noticable wind noise, either (cone excursion hits around 5mm p/p) The PRs are great for very low tunings in small cabinets, but they're not needed here: you may as well put the extra money elsewhere.
Chris
I'm happy to help where I can - its a really good feeling when people come over to say hi and enjoy the music.
Also, there's not much need for passive radiators for outdoors (unless you want a waterproof enclosure), as the ports end up quite small because of the relatively high tuning. This also keeps air velocity down: my woofers have a couple of bits of 40mm pipe for ports. About 11cm long each, IIRC. No noticable wind noise, either (cone excursion hits around 5mm p/p) The PRs are great for very low tunings in small cabinets, but they're not needed here: you may as well put the extra money elsewhere.
Chris
Haha.. It WAS long, and way over my head. But I DO appreciate it.
This forum seems a place where professional audio and electronic engineers come to discuss their profession. I'm no where near that level, but I AM a fast learner.
I just love forums and use them for EVERYTHING! My car, motorcycle, computer, etc..
Not sure if there's a more... lamen based audio forum. I had never even ehard of Class T Amps until I posted to this forum.
All the terms, rules, calculations, tunings, etc are way over my head. Maybe if Iw ant to get serious with this hobby of mine is to take some classes.
I have a few very well respected audio engineers in town as well that I should hit up.
So, thanks for the advice. Especially the basic explanation of why the PRs aren't really needed. That's the best kind of help.
Wow, hey. I joined at 14 years old. I'm now studying Physics at university.
Expert? Nope.
His site is running slow at the minute, but have a look at Rod Elliott's articles. There's a man who knows what he's doing: I gained most of my knowledge from reading those articles of his.
A few things you can do to get up-to-speed:
1 - read those articles I mentioned. Anything that takes your fancy.
2 - Download WinISD Pro. Add your Peerless woofers, and see what happens with different cabinets, changing the size of the cabinet, the ports, etc, etc. That'll give you a better understanding of what does what. Once you've had a play around, you'll have a million questions. Keep playing until you've answered some yourself, and then let us know what still doesn't make sense (or PM me if you think its a really daft question
) and we'll try to help out.
If you find some more time, feel free to break down my post and ask questions about each bit. I'll be rather busy over the next few days (turns out universities want us to work for our degrees - who knew?), but I'll get back to you eventually, or perhaps one of the other guys here will answer your questions.
Chris
Expert? Nope.
His site is running slow at the minute, but have a look at Rod Elliott's articles. There's a man who knows what he's doing: I gained most of my knowledge from reading those articles of his.
A few things you can do to get up-to-speed:
1 - read those articles I mentioned. Anything that takes your fancy.
2 - Download WinISD Pro. Add your Peerless woofers, and see what happens with different cabinets, changing the size of the cabinet, the ports, etc, etc. That'll give you a better understanding of what does what. Once you've had a play around, you'll have a million questions. Keep playing until you've answered some yourself, and then let us know what still doesn't make sense (or PM me if you think its a really daft question
) and we'll try to help out.If you find some more time, feel free to break down my post and ask questions about each bit. I'll be rather busy over the next few days (turns out universities want us to work for our degrees - who knew?), but I'll get back to you eventually, or perhaps one of the other guys here will answer your questions.
Chris
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