Buckapound, yeah you can use the input impedance resistor of the amplifer and the coupling cap to give you a desired 6dB rolloff, but it will only be a 6dB rolloff, which will save power but not as much as it could. A lot of these projects will be fed signal from devices designed to drive headphones, so you could easily make at least a 12dB passive system high-pass network with such a low source impedance. 4.7uF and 470 ohms gets you 72Hz for the first stage, for example, at a load an MP3 player wont mind at all.
Guitar Pedals: R-C Filter Calculator
Passive Line-Level Crossover (it's not complicated)
Guitar Pedals: R-C Filter Calculator
Passive Line-Level Crossover (it's not complicated)
I think I might actually have found the 4ohm version of HP10W here:
Strassacker: Lautsprecher - Boxen - Selbstbau
around the middle of the page!
Hope this helps those of you who are looking for it
Strassacker: Lautsprecher - Boxen - Selbstbau
around the middle of the page!
Hope this helps those of you who are looking for it
A lower Qts yields a smaller box with a higher tuning frequency. I'm not familiar with those drivers at all so it would be best to try getting a datasheet straight from the manufacturer to work with.
You could try these calculators to give you a ballpark idea about box design:
AJ Audio Subwoofer Box Enclosure Design Software - Sub Speaker Cabinet Building Program Downloads
You could try these calculators to give you a ballpark idea about box design:
AJ Audio Subwoofer Box Enclosure Design Software - Sub Speaker Cabinet Building Program Downloads
Havoc08 said:
You can see the numbers here:
An externally hosted image should be here but it was not working when we last tested it.
It is a cheap battery (249kr). I can see these numbers are for charging, so maybe that doesn't comply with drawing power from it, but I can't find any info on that.
Do you have a link to your batteries?
Ps. sorry for mis-quoting you as someone else in my last reply.
Yes that's charging current info. A fully charged generic 7AH lead acid battery in good shape will happily source the current peaks you need, though ideally average current would probably be more like an amp or less for that size battery.
Notice the standby versus cycle storage voltage ratings. For your application you want the cycle voltage. This will give you the maximum capacity of the battery.
What size supply filter capacitors are being used? Going a little generous here could help you stay on a more efficient portion of the impedance curve of the battery, while decreasing total supply impedance, especially at reduced charge.
Notice the standby versus cycle storage voltage ratings. For your application you want the cycle voltage. This will give you the maximum capacity of the battery.
What size supply filter capacitors are being used? Going a little generous here could help you stay on a more efficient portion of the impedance curve of the battery, while decreasing total supply impedance, especially at reduced charge.
Nice, thanks! Now I don't need to worry about that anymore
Sorry, I don't know what you mean. If it requires changing components on the amplifier, I think we will pass. Hopefully we will have it build for us, and never touch it again with a soldering iron
The main concern is to get it to work without blowing anything up, and getting as much volume out of the boominator as possible.
I guess an easy solution would be to buy 4x 4ohm HP10W and connect each to it's own output of the Amp9, which would give us 4x100W as I understand.
However, if it's possible to parallel the 4ohm's into two pairs of 2ohms and thereby get even more wattage, it would be ideal. But I still haven't figured out whether it is possible or not, or which option is better.
Well don't bother with the capacitors then, but if you're looking for max output power I would definitely suggest again looking at the high pass filter. A little algebra will translate into either less lead to carry or longer, louder running times.
7AH means 7 Amps for 1 Hour, but the ratings are typically given for a 20 hour cycle. So at 7 Amps you are likely to get much less than an hour, because at high current you start losing a lot more power in the battery's internal resistance.
That battery isn't going to cut it for more than "100 watts". RMS output power at that level probably wouldn't last more than 30 minutes with a brand new fully charged battery.
7AH means 7 Amps for 1 Hour, but the ratings are typically given for a 20 hour cycle. So at 7 Amps you are likely to get much less than an hour, because at high current you start losing a lot more power in the battery's internal resistance.
That battery isn't going to cut it for more than "100 watts". RMS output power at that level probably wouldn't last more than 30 minutes with a brand new fully charged battery.
Okay! So you are saying that we actually shouldn't bother with trying to parallel into 2 ohms and stuff, since the battery will die very fast at such high wattage?
If that is what you are saying, then I think we will just settle with the Amp9 and 4x HP10W 4ohm, one into each channel, and then try to not turn it to the max, which would use very much power.
The high-pass you are talking about, will that function as a cut-off below 80Hz to save power? And do you have any info or link to how this is done?
It's very kind of you to help with this basic stuff
If that is what you are saying, then I think we will just settle with the Amp9 and 4x HP10W 4ohm, one into each channel, and then try to not turn it to the max, which would use very much power.
The high-pass you are talking about, will that function as a cut-off below 80Hz to save power? And do you have any info or link to how this is done?
It's very kind of you to help with this basic stuff
4 Ohms, 4 channels is plenty of a load for that battery. I wouldn't go to 2Ohm without increasing the battery.
"The high-pass you are talking about, will that function as a cut-off below 80Hz to save power? And do you have any info or link to how this is done?"
Well, yes! Look at my previous posts in this thread. THere are even links to use.
Have fun.
"The high-pass you are talking about, will that function as a cut-off below 80Hz to save power? And do you have any info or link to how this is done?"
Well, yes! Look at my previous posts in this thread. THere are even links to use.
Have fun.
Oh sorry, didn't see that, but thanks!
I want to mention though, that we do have 2 batteries, which we will connect in series to get 24v
But it sounds like we should stick with the amp/speaker setup as mentioned. No reason to use the batteries in 2 hours or whatever. It should hopefully last all nightBy bridging you get twice the power at the same impedance as it is a kind of push-pull principle as described by other user. By paralleling you ake the amp capable of delivering twice the power, but only if you decrease the impedance.
You can see the numbers here:
An externally hosted image should be here but it was not working when we last tested it.
It is a cheap battery (249kr). I can see these numbers are for charging, so maybe that doesn't comply with drawing power from it, but I can't find any info on that.
Do you have a link to your batteries?
Ps. sorry for mis-quoting you as someone else in my last reply.
That is the same type as mine. It will do just fine. You can optionally add a capacitor of 15-20mF for better bass management. Thos type of batteries give 2-400 amps in very short bursts as that i needed for starting a motorcycle or similar. Power delivery is not an issue as ong as you use proper size cables.
Okay! So you are saying that we actually shouldn't bother with trying to parallel into 2 ohms and stuff, since the battery will die very fast at such high wattage?
If that is what you are saying, then I think we will just settle with the Amp9 and 4x HP10W 4ohm, one into each channel, and then try to not turn it to the max, which would use very much power.
The high-pass you are talking about, will that function as a cut-off below 80Hz to save power? And do you have any info or link to how this is done?
It's very kind of you to help with this basic stuff
Even at max it will last more than 30 minutes. You can't just calculate the amperage drawn as 400watt/24v = 16,7A as music signal does not behave like this. As previously mentioned music signal are way lower than you estimate it to be as only few frequencies are played at the same time.
I can assure you that no matter which amp you choose the boominator will play loud! just inherent to its sensitive design. 90dB at 1 watt is alot of sound and the boominator is above that. You will likely draw less power on account of not having to turn the volume up so far as the sensitivity is working for you.
Thank you Havoc. I do know now that playing at max volume on a 4x100w amp doesn't consume 16,7A. Do you have an approximate for how much it would use when playing electronic music on max volume?
And where should we place the capacitor? (and what does bass management actually do?).
And where should we place the capacitor? (and what does bass management actually do?).
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Max power consumption with music roughly equals max RMS/5, so 4x100Wrms at 24V equals 3.33A or 80W. That's still suck 2 of these 7Ah SLAs dry in under 2 hours.
RMS power rating of an amplifier has more to do with continuous wave power capacity before clip. So 400WRMS means it will take more than 400W to produce the waveform through an amplifier. At that point there is no possible reduction factor, if the amp has to barf it out, it has to come from the battery and capacitors. The power envelope of an audio signal varies so much it is impractical altogether to come up with a reduction factor of peak output versus average input. Bodies have gotten together and tried but there isn't what you'd call general agreement.
Audio power - Wikipedia, the free encyclopedia
Personally I'd say you're better off to design to handle peak demand of the system, plus some continuous battery load that it can handle, which the thing at the end of the volume control will have to manually regulate, unless you add an automatic level control circuit. You could add a cheap ammeter if you really wanted to tech it out.
Audio power - Wikipedia, the free encyclopedia
Personally I'd say you're better off to design to handle peak demand of the system, plus some continuous battery load that it can handle, which the thing at the end of the volume control will have to manually regulate, unless you add an automatic level control circuit. You could add a cheap ammeter if you really wanted to tech it out.
Oh sorry, didn't see that, but thanks!
I want to mention though, that we do have 2 batteries, which we will connect in series to get 24v
Good. I was wondering how you expected to get those power figures with 24V P-P into 4 ohm. Definitely don't waste your time trying to load 2 of those batteries in series with 4 BTL switching amps channels loaded at 2 ohms. You're a bit under matched with that battery even at 4 ohm with 24 volts supply, unless you save the last 3dB for rare peaks. Like you said, if you hear clipping you have it set way too loud.
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In the past Sony used a simple RC network after a signal diode with cathode connected to the audio output. A bleeder resistor set the decay of the limiting, and the input resistor set the attack. They fed the voltage on the capacitor back to the 100Hz center on a linear voltage controlled parametric EQ IC. In other words they dialled back the bass when the overall signal got too large. So, this problem has been addressed in various ways in commercial boom box offerings. It would be fairly easy to do something like this with your input filter, but you would need some active circuitry. At this fidelity level it could potentially be pretty basic.
Please note this is specifically for the amp9b or amp6b which has 90% effciency, assuming the source is able to load the amp to -0 dB, and that the music roughly follows the RIAA recording standard.