Aj72 Posted March 5, 2015 Share Posted March 5, 2015 I'm using mini DSP for sub EQ. I'm happy with the result but there is white noise audible from the listening position. Any suggestions for how to reduce it? Link to comment Share on other sites More sharing options...
maxmercy Posted March 5, 2015 Share Posted March 5, 2015 Try to ensure your gain structure is maximized. Noise adds as more components are added to the chain, ensure the signal is strong enough but not clipping, that way your amp does not have to be set at max, amplifying the noise floor as well as the signal. If still noisy, upgrade firmware, reset, and if still no go, contact MiniDSP. JSS Link to comment Share on other sites More sharing options...
nube Posted March 6, 2015 Share Posted March 6, 2015 You might also consider your 12vdc power source. If it's not wired properly, or the wall wart is wrong/bad, I'd think it could incorporate similar noise. Link to comment Share on other sites More sharing options...
Kvalsvoll Posted March 6, 2015 Share Posted March 6, 2015 A simple RC 1. order passive lowpass on the output will reduce noise, consider it a necessity if using real woofers with low moving mass and large motors. Also put a capacitor on the psu connection at the minidsp board, the larger the better. Getting proper dynamic headroom using the minidsp 2x4 is a challenge, but it is possible. Link to comment Share on other sites More sharing options...
Shredhead Posted March 6, 2015 Share Posted March 6, 2015 Getting proper dynamic headroom using the minidsp 2x4 is a challenge, but it is possible. Why do you say that, is it noisey or something like that? Has anyone measured it's noise floor? Link to comment Share on other sites More sharing options...
Aj72 Posted March 6, 2015 Author Share Posted March 6, 2015 I've tried battery powered laptop off usb and this was slightly better but haven't tried just a battery. I've heard a car battery is better but how do you hook it up? I have to admit that I actually paid somebody to come and eq the subs for me as I didn't know enough about what I was doing. I need to read a bit more but I wanted it done properly so I knew what it should sound like. Funny thing is I was able to achieve a similar result at my old place with a MIC2200 all by myself using a Dayton V2 Omnimic. I'd take that result any day and transfer it to my new place but I wasn't able to achieve it here despite recording a fairly flat response + or - 8dB. I'm starting to think I didn't use my Omnimic correctly when recording as the real world result didn't sound as it showed on the graph. The graph actually looked quite similar to the one I recorded at my old place. This is the problem when you don't know enough about what you're doing! I have found that my room response is actually quite good for bass so I'm puzzled why I couldn't achieve a result myself using MIC2200 as I did before? Link to comment Share on other sites More sharing options...
Aj72 Posted March 6, 2015 Author Share Posted March 6, 2015 I found out I was running the wrong plugin which wasn't helping the cause here. I bought the 2 way advanced 21 but just needed the 2 way advanced. The upside of this is that the level has improved a bit so I'm not running the gains as hot on my MIC2200. The depth/weight of bass effects has also improved, real crunch to Edge of Tomorrow bass that was slightly missing before. White noise is still present but less as running everything less hot now. Maybe that it's not enough to bother me anymore. Will have to watch a few movies to find out but loving what the EQ has done for my bass, so clean! Link to comment Share on other sites More sharing options...
Kvalsvoll Posted March 6, 2015 Share Posted March 6, 2015 Why do you say that, is it noisey or something like that? Has anyone measured it's noise floor? When you have a subwoofer system with 120db+ capacity, and the drivers have lightweight cone and large motors, because that is what is best suited for a compact horn subwoofer, then there will be problems with noise, because the drivers does not fall off at higher frequencies like a heavy-cone sealed driver would. The minidsp is no better or worse than any others on the market, and noise and headroom specs are listed in the documentation provided from the manufacturer. It is just that it is not good enough. To get a noise-free system it is required to adjust the gain structure so that the minidsp barely can drive the amplifielrs to clipping, and the both the rc-filter on the signal output and the cap on the psu is required. Link to comment Share on other sites More sharing options...
maxmercy Posted March 10, 2015 Share Posted March 10, 2015 Where would you put the cap on the PSU? I thought it was a DC power supply. JSS Link to comment Share on other sites More sharing options...
Kvalsvoll Posted March 11, 2015 Share Posted March 11, 2015 On the power supply connector, from + to -. 2200uF or larger, get a good capacitor with low serial resistance. Link to comment Share on other sites More sharing options...
Aj72 Posted March 12, 2015 Author Share Posted March 12, 2015 Kvalsvoll can you please explain to me what an RC 1 Passive order low pass on the output is and how I can engage it? Also when you say capacitor on the PSU are you talking about a large battery which then removes the need for directly plugging into a PowerPoint? I see Nube you suggested this also. I have read that hooking up power through a car battery can improve things but how do I go about connecting the battery to the mini DSP? Link to comment Share on other sites More sharing options...
Kvalsvoll Posted March 12, 2015 Share Posted March 12, 2015 Battery is one solution, but not really necessary. An ordinary electrolytic capacitor across the psu leads fixes the noise and distortion problems at lower frequencies. A rc-filter is a resistor in series and a capacitor from signal to ground after this resistor, I don't have the values for the one I made, but around 2K resistor and a capacitor value calculated for a roll-off somewhere between 200hz to 2khz should work fine. You don't need a degree in electronics engineering to do these simle fixes, but you will need a basic understanding of electronics and how things work. Link to comment Share on other sites More sharing options...
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