nilsonsound - an ongoing story |
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nilspixel
Registered User Joined: 02 March 2021 Status: Offline Points: 77 |
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sure it does ;) just for a completion of this diary here...
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infrasound
Old Croc Joined: 13 May 2011 Location: Brizzle Status: Offline Points: 2276 |
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One cabinet with a 150W input is going to run out of steam before your mids and tweeters, especially outdoors. Looks up ISO 226 to get an idea of relative SPLs.
And as bob mentioned, the empty cabinet next to it may absorb some of the energy radiated. Don't worry about the THD, anything below 1% at amplifier is decent enough. You won't be playing sine waves for long durations, so your cables will be quite overspecced'. You could potentially reduce their size if they're unmanageable (bend radii / mass). Shorter is always better of course. Edited by infrasound - 31 August 2021 at 5:42pm |
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nilspixel
Registered User Joined: 02 March 2021 Status: Offline Points: 77 |
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What i ordered today: ...LiFePo4 100AH 200A (400A max.) + Shunt ...Rage 1200.2
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nilspixel
Registered User Joined: 02 March 2021 Status: Offline Points: 77 |
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Update: I installed the rage 1200.2 today. agm is replaced by lifepo4. problem: after ~1 min after I powered up the rage Amp the Pioneer starts to make a high frequency sound.. when I turn off the rage this tone disappeares instantly.. what's going on here?... any ideas?
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infrasound
Old Croc Joined: 13 May 2011 Location: Brizzle Status: Offline Points: 2276 |
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Feedback on the ground line / power heading down the signal ground is my guess.
Does it go away if you disconnect the signal connections? Try buying a ground loop isolator and adding it on the inputs to the rage amplifier.
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nilspixel
Registered User Joined: 02 March 2021 Status: Offline Points: 77 |
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I was wrong! But thanks for your reply!
The probelm was the new rage itself. I opened up the whole thing to check if parts are loose. i tightened some screws, noise is gone. But one problem remained: As soon as i use the second amp (rage) my high speakes start to make weird noises even though there is no signal coming from the dsp. i wired both power cables directly to the battery +. When i disconnect the rage from the battery, noise is gone. My assumption is that both amps interfer with each other somehow... may a powercap solve the problem? Any ideas on that?
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infrasound
Old Croc Joined: 13 May 2011 Location: Brizzle Status: Offline Points: 2276 |
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Powercap, no. They are of questionable effectiveness to stop voltage drops - and you aren't pulling anywhere near enough to be in that realm anyway.
My answer to your last point is more or less the same, so not wasted. Because the power GND and signal wiring in 12v systems are often shared (or too closely related), it can be needed to isolate them to prevent interference. My suggestion is to try the isolator in various spots until the problem disappears. Or, it may work to use a separate isolated DCDC power supply for the DSP |
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nilspixel
Registered User Joined: 02 March 2021 Status: Offline Points: 77 |
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thanks a lot infra! I'm going to try your suggestions today to see if it affects anything ;)
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studio45
Old Croc Joined: 16 October 2007 Location: United Kingdom Status: Offline Points: 3863 |
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I'd guess that a high pitched whistle is gonna be due to the two Class D amp's oscillator frequencies interfering with each other and producing an audio-frequency tone. Most amps use a free-running oscillator whose frequency isn't particularly stable or locked to any reference clock, so if you've got two amps on the same battery bus, and one is running at 400kHz and the other one 405kHz, you're going to get signals of 5 and 805kHz appearing on the system ground.
I've also experienced noise emanating from cheap Bluetooth reciever boards - this is due to the chip involved pulling very short, sharp pulses of current from the supply at a rate with at least some audio-frequency components. No amount of passive filtering (extra caps near the BT board) makes it go away. The only way is to use little 5v-5v isolated converter bricks to power the BT board. However of course you need to connect signal ground "around" the isolator somehow otherwise there's no circuit for the audio signal to flow. Using a 1000uF cap across the rail after the isolator and a 100r resistor to link BT ground to audio ground seems to work well for me - the 100r is enough to make most of the interference flow thru the 1000uF cap to the isolated ground rather than out onto your audio ground. Small transformers would also work but more expensive.
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Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA
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samsk
New Member Joined: 12 May 2021 Status: Offline Points: 8 |
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Hey, been really interesting to read this and really great system! I've built a similar 12v system this year (I've done a post here which can be found under 'compakt sound system'). I'm struggling to get my mini dsp to sound good, lots of unpleasent crackling noises, it sounds great when I take the dsp out or power it from my 240v amp rack, I was wondering if you'd be up for sharing some more screen shots of your setup? The crossover screenshot was really useful but I'm not sure about the other settings. If you'd be up for it maybe you could send me your settings as a preset file? Big thanks, Sam
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nilspixel
Registered User Joined: 02 March 2021 Status: Offline Points: 77 |
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Does anyone know if its a bad idea to get a different speaker unit for the secons still empty tham? the PD1550 is not available at this moment.... i was looking at Eighteensound
15LW1401 instead.. Eighteensound 15LW1401PD1550 |
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