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New efficient neo system

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Thomas Hosker View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Thomas Hosker Quote  Post ReplyReply Direct Link To This Post Posted: 26 March 2016 at 11:31am
Cheers for the input S45, ive seen a few pics and vids of your system, im assuming your using the same amp as me? TAS5630?

How do you find the levels on your rig? Also whats battery consumption like? Im guessing your giving it around 40 volts?
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slaz View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote slaz Quote  Post ReplyReply Direct Link To This Post Posted: 26 March 2016 at 12:57pm
Originally posted by studio45 studio45 wrote:

I use the KMTech boards for crossovering, available on eBay - he has several flavours; I've got them running straight off the battery voltage with a virtual earth circuit for the 0v rail, then capacitor-coupled at the outputs into a 2x300w Sure board. No ground loop issues - you don't need to connect the ground between thecrossover output and amp input. 
I'm using a 3-way board configured with 50Hz and 100Hz points - so I drive my sub from the "mid" output, and it recieves 50-100Hz, and the mid-tops from the "high" output, and they recieve 100Hz+. I haven't found a crossover board with a freely configurable highpass on the input, so this is my workaround.
I'm still not on the miniDSP hype, it just costs too much for what it does. FreeDSP is *much* more interesting ;)


Seems like a pretty decent solution to me.

Is that Xover board well-behaved ? Is it powered directly off battery or via some converter/controller etc. ? If the former, does it tolerate voltage changes/fluctuations OK ?

REMEMBER....POLITICIANS AND DIAPERS SHOULD BE CHANGED OFTEN AND FOR THE SAME REASON
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Thomas Hosker View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Thomas Hosker Quote  Post ReplyReply Direct Link To This Post Posted: 24 April 2016 at 1:09pm
Got all the parts now, just slowly putting them together and doing some testing.

Think i need a pre-amp to stick in before the miniDSP. Any recommendations? A nice quality board with either 12 or 5v power would be perfect.

Theres some videos on here...

https://www.facebook.com/groups/252189101793584/
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studio45 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote studio45 Quote  Post ReplyReply Direct Link To This Post Posted: 24 April 2016 at 2:43pm
Originally posted by Thomas Hosker Thomas Hosker wrote:

Cheers for the input S45, ive seen a few pics and vids of your system, im assuming your using the same amp as me? TAS5630?

How do you find the levels on your rig? Also whats battery consumption like? Im guessing your giving it around 40 volts?

Yes I'm using the TAS5630 power amp, I run it at 48v from a Sure 500w boost converter board. Levels are great, I can get her up to full power from an iPhone given a well-normalised track. My input goes in via a transformer then a 10k volume pot, which pretty much defines the input impedance - the KMTech board appears to be really high impedance at the input (100k or more). About 0.9v RMS with the power amp gain switches set to 36dB, gets you cooking with gas. With 1.4v RMS from my laptop, I can't quite get the front panel volume control up all the way without clipping. Batteries I've been using are 38Ah Yuasa lead-acids, old ones - probably not at full capacity any more, but I can get a good 6 or 7 hours on a charge at full beans.
I'm actually just in the process of changing the power arrangement for the crossover though - I decided I didn't like it running on the unregulated battery voltage, although it was perfectly well-behaved. All the sagging and discharge envelope going on just can't be good news for transient reproduction. So, I went back to the small 3 amp XL6009 boost converter boards I bought last year, which I had discarded for being too noisy; they would create a low droning noise in the speakers if I used them to power the crossover directly. I decided to try post-regulating the output with an LM317 linear regulator to see if it would get rid of the switching noise. Initially, this seemed to work really well, and I was able by adjusting the two regulators, to get the rail up to 30v from my 12v battery; and it was rock-solid too, no matter what the battery voltage was dropping to. Did a whole gig with no problems, all night. 
However, I then tried it with my higher-voltage lithium battery pack, and to my dismay the switching noise returned! This turns out to basically be a problem with the small converter boards - seems they can break into an oscillation mode if lightly loaded, and the fault/mode can be pretty intermittent. Like I can poke it with my finger, or just look at it sideways, and that can be enough to start it off. They're apparently more stable on 12v than 16v, or maybe I just have a couple of slightly broken units. 
But anyway, through this whole process I'd had it in my mind that you can't put more than 42v into an LM317, so I couldn't just use it to drop my main 48v rail to 30v for the preamp. But, on reading the fecking datasheet properly, it turns out that's just the maximum differential voltage it can take - ie, you can't use it to *drop* more than 42v off your high rail. Derrrr. So 48v to 30v at about 50mA, is no bother at all. It should have a fuse inline though, cos if what's downstream shorts to ground, 48v will definitely blow it right up.
So, that's my solution - just got to wire it up now ;)
Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA
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