PR is the SB Acoustics 5 x 8 mentioned earlier in this thread. Oval form factor works well in my application because it leaves room on the front face for a RaspberryPi touchscreen.
Ahh cool, got it.
Well the sims are very similar.
I tried 2x Speakers and the 5x8 passive you mentioned.
Yellow line is similar to your sim.
So my assumption was correct.
The passive is heavy enough to get a FB of around 40 Hz.
and likely for the flat response you want to see. Tuning needs to be raised to 48 Hz
Passive is slightly too heavy for tuning you would like.
I got it to work...but I added another 5x8 passive radiator then added 14 grams to each.
Orange Line is with higher tune/2x passive.
Probably try 2 matching 6 1/2 passives. To be able to fit the screen.
Everything be round...Dayton makes matching 6.5 radiators.
Thanks for the pointers. I've got a few good looking designs modeled in hornresp, but now have other questions:
- the Dayton DCS165-4 6.5 has xMax of 6mm, but hornresp shows diaphragm excusion of just under 10mm at the frequencies I care about. I assume this is a deal-breaker?
- If I use Tang Band W6-1139 instead, there's plenty of xMax and the output curves look even nicer, but W6 is only 50W power handling and the 7498e amp board I'm using pushes 160W per channel into 4 ohms. I'm inclined to think these generic class D boards are wildly optimistic in their output specs, but we're talking about a factor of 3 here. Opinions?
Not so much a deal breaker as a bit more peak distortion.
The W6-1139 has nearly double the Xmax (6mm to 11.5mm) so should have nearly 6dB more clean output potential. The Dayton has only 3dB more power average power handling (100w vs 50). Unless you play really compressed music, most will average less than 1/8th power, reaching 160watt peaks would average 20 watts or less.
Woofer harmonic distortion is usually fairly low order, not too objectionable.
Amp distortion tends to be high order- a little goes a long way. With a 32v PSU, the 7498e amp is in the 30% THD range (about -10dB from the fundamental) at 160 watts, bass peaks probably would sound terrible, like "AKKK, AKKK".
Looks like around 100 watt peaks with a 32v supply might be the limit before the amp, not the speakers, start sounding bad.
I'd choose the W6-1139, and try to keep the amp from clipping.
Art
Sounds about right, I dont think I got much more than 60 watts
with the dayton drivers before you would be hitting a lot of distortion.
If the tang band models better, go for it
a pair would be 100 watts.
Its going to be a major tradeoff with any small driver which
can do low bass.
For the most part, getting 50 Hz in 10 to 15L is pretty amazing.
Of course getting 50 Hz with many drivers is rather easy...
but it dont happen in 15 Liters.
So its pretty cool what driver designers pull off these days
On battery power I would be more worried about sensitivity.
And use whatever gave more SPL with less power.
with the dayton drivers before you would be hitting a lot of distortion.
If the tang band models better, go for it
a pair would be 100 watts.
Its going to be a major tradeoff with any small driver which
can do low bass.
For the most part, getting 50 Hz in 10 to 15L is pretty amazing.
Of course getting 50 Hz with many drivers is rather easy...
but it dont happen in 15 Liters.
So its pretty cool what driver designers pull off these days
On battery power I would be more worried about sensitivity.
And use whatever gave more SPL with less power.
For once, this is actually in my wheelhouse. Desktop systems are fairly unique. Issues such as 'room correction' are largely irrelevant because the user is so close to the output. Even quoted stats like SPL need to be taken with a pinch of salt. These stats are quoted @1m - the user of a desktop system is invariably within this distance.
Anybody who wants to throw 400w at a desktop system is either: (a) divorced, (b) lives in his parent's basement and doesn't pay the the electric bill, (c) an idiot.
Basic rules of thumb apply: diagphram area trumps Xmax (efficiency). For a 50Hz response in a 10 litre cabinet a 5" driver in a ported cabinet or a 6.5" in sealed cabinet will do the job.
Anybody who wants to throw 400w at a desktop system is either: (a) divorced, (b) lives in his parent's basement and doesn't pay the the electric bill, (c) an idiot.
Basic rules of thumb apply: diagphram area trumps Xmax (efficiency). For a 50Hz response in a 10 litre cabinet a 5" driver in a ported cabinet or a 6.5" in sealed cabinet will do the job.
I'm neither (a) or (b), so must be (c).
I'd be perfectly happy to throw 400w/ch at some desktop speakers if the need arose. In fact, 1x W6-1139 in a 2L box (good luck fitting it in) would need 400w to hit 83dB@20Hz@1m. Not a crazy SPL, but pretty useful. I might try it.
Given that music rarely has sustained power in the LF, the amp would be delivering that sort of power on a very low duty cycle, so actual draw from the mains wouldn't be particularly high.
For clarity, Surtsey, are you saying that all 6.5" drivers in 10L sealed boxes will hit 50Hz?
And all 5" drivers in ported boxes?
Or just one particular driver, which you've yet to reveal the make/model of?
Chris
I'd be perfectly happy to throw 400w/ch at some desktop speakers if the need arose. In fact, 1x W6-1139 in a 2L box (good luck fitting it in) would need 400w to hit 83dB@20Hz@1m. Not a crazy SPL, but pretty useful. I might try it.
Given that music rarely has sustained power in the LF, the amp would be delivering that sort of power on a very low duty cycle, so actual draw from the mains wouldn't be particularly high.
For clarity, Surtsey, are you saying that all 6.5" drivers in 10L sealed boxes will hit 50Hz?
And all 5" drivers in ported boxes?
Or just one particular driver, which you've yet to reveal the make/model of?
Chris
No, I'm not saying that at all. I'm being pragmatic. I'm aware, if not intrigued by, the technical discussions but at some point you're pi$$ing in the wind.
The basic premise: in the blue corner - guys on a forum using manufacturer's published TS parameters (which have an accuracy of +/- 25%) running simulations using software they downloaded for free from the Internet. In the red corner: multi-national corporations with millions of dollars and thousands of engineers at their disposal.
In the last 2 years I have had a multitude of small subs. For example: 'everybody' makes a 20l ported sub with an 8" driver. I have had: Polk-Audio, Tannoy, Yamaha, LG, Gale, Wharfedale. They're much of a muchness (the Gale was garbage). The Polk (30Hz) sounded good in the bedroom but nowhere else.
You're something of an expert. Any 'subwoofer' driver can do 50Hz, A simple efficiency calculation: double the power to gain 3dB vs tuning the port to give you +3dB around your chosen frequency.
Bottom line: give me an unbranded 6.5" sub driver, I'll tell you, you need 10 litres.
To put it another way: XR3i (105hp), Golf GTi (108hp), Astra GTE (113hp). I've had all three. We could discuss them for hours. I liked the Golf best but all got me to work in 35 minutes.