Mini DSP talk

[kgveteran]

Anyone using these processors and interested in some questions..

[Nate Hansen]

I've been using the 2x4 for about a year now, so I can speak to that version....

[kgveteran]

Mine should be here soon, i ordered it saturday.

Is it as intuitive as others say ? I have to calibrate my quad sealed 15's and two separate sealed 12's near field to smooth out the FR at the LP.....

I purchased the 4way advanced plugin.....

[Mattcc22]

I also just ordered one last Friday. I got the 2x4 in a box version and think I just need the 2 way advanced plugin. I currently have one sub running off one side of a behringer ep2500 but will be adding a second sub hopefully soon. Right now my only question is whether I should run the subs off seperate outputs to the amp so I can control them seperately or if I should just run mono to the amp and run the amp in stereo. Both subs will be at the front of the room same distance to the listener (unfortunately no other option on that).

Yours looks to be a bit more challenging though, so good luck to you

[kgveteran]

Here's a link to the thread over at AVS http://www.avsforum.com/avs-vb/showthread.php?t=1380013

[gainphile]

Used it for a few years now. A godsend for DIYers!!

[Hdale85]

I was considering them for my car build, but there have been some issues with noise in the car. Also I'm running a rather powerful CarPC so I decided to use my Firewire 410 and some software to do the crossover work But the Mini-DSP still intrigues me. It's certainly not as powerful as some newer processors that have recently come out and coming out soon (at least for the car side of things), but they're pretty nice for what they cost.

[kgveteran]

Used it for a few years now. A godsend for DIYers!!

Any advice for newcomers....

[gainphile]

The board pretty much self explanatory and easy to configure. And I guess you already know we really don't care about text book filters but rather the acoustic output of the drivers. So the learning curve is not that steep I guess.

If you'd come from passive xo I can only guess future happiness when you don't need to care about driver impedance load and sensitivity

What differentiates MiniDSP from DCX2496, etc are:
- Linkwitz transform
- Cascaded filters
- Any other custom biquad programming

They require some experimentation to see what's going on.

[kgveteran]

The tuning subs will need a bandpass of 40hz-80hz, as that is the null the main system is producing at the LP.

The main subs will need a little LT, due to their sealed alignment. There's alot of cabin gain in the room at the LP, so as you state, i can dial in and measure with OmniMic in realtime....quite a step forward for DIY.

[kgveteran]

can anyone explain the input sensitivity on using pro amps versus plate amps. i have a balanced version on its way and i want to be sure. i will be using both pro amps and plate amps.......might as well address the sub out voltage too...

[BobEllis]

Input sensitivity depends on a number of design choices. Look for manufacturer's specifications. For example, an Outlaw model 7700 will need a 1.45V signal to reach full rated output, while Crown rates its pro amp sensitivity at 1.4V (8 ohms load) and Behringer says it's 1V for the EPX2000 to reach maximum output.

The pro amp spec sheets don't specify whether the sensitivity is balanced or unbalanced, but they accept both. Outlaw specifies that the unbalanced inputs have 6 dB lower gain than the balanced inputs, but not which input was used for their sensitivity is rating. The 6 dB difference is due to the differential nature of balanced inputs effectively seeing twice the signal voltage on either input. My bottom line - use a converter to drive pro amps with a balanced signal unless you have an output capable of driving very high voltage unbalanced signals.

[kgveteran]

Is there an established method for testing output levels so i dont over drive the amps ?

[Hdale85]

Could use a volt meter and feed it sine waves.

[kgveteran]

Could use a volt meter and feed it sine waves.

Simple DC voltage ? Ok.

[BobEllis]

DC Sine waves?

Why not just assume that you don't want to lose your hearing, and assume that if you don't feel it is uncomfortably loud for more than a few moments and sounds clean you aren't overdriving the amps?

IMHO, you are over thinking the issue. In PA use you might need to worry about not overdriving the amps (and the resultant speaker frying) In home use, it's not an issue for most people.

Let's say your sub sensitivity is around 85 dB/1 watt midband with 10 dB of boost in the bottom octave and you drive it with a kilowatt amp. Subtract 10 dB from the sensitivity to compensate for the boost, leaving you with 20 dB above 1W. Ignore power compression for the moment and you still should reach close to 105 dB without clipping. If the signal doesn't include a full level portion in the boost range you're looking at close to 115 dB peak.

Power compression is the result of voice coil heating due to high (average) power signals. In home use it probably isn't a very significant factor unless you listen to highly compressed music at ear splitting volume. Driver design including voice coil cooling details affect this. I generally listen at less than a watt, so even 20 db peaks of short duration don't heat the voice coils much.

[kgveteran]

^^^^ yup, thats what i thought. over thinking again. Just had to ask just in case i was missing something, cant wait for my mic cable to come in so i can get this rig up and running.

[BobEllis]

Let's stamp out analysis paralysis in our lifetime!

[Hdale85]

In car audio that's how we set the gain on amps. Sine waves and a volt meter on the outputs. I don't think you need the speakers connected.

You're running pro amps though so I don't think you'll have an issue with providing too much input.

[exojam]

You could get a little o'scope and check the signal coming from your front side to see what is getting to your amp inputs.

James

[jheizer]

I was considering them for my car build, but there have been some issues with noise in the car. Also I'm running a rather powerful CarPC so I decided to use my Firewire 410 and some software to do the crossover work But the Mini-DSP still intrigues me. It's certainly not as powerful as some newer processors that have recently come out and coming out soon (at least for the car side of things), but they're pretty nice for what they cost.

Hmm as a fellow carpc/vst host person glad I saw this. I had debated before trying out a mini dsp or two in the car. Glad I didn't and will have to remember this.

[kgveteran]

My subs are humming like there is no tomorrow.... What to do. Cant lift grounds its a no-no. Do i run crazy grounds from everything that has none...

Good God Help Me hahahahahaha

[sfdoddsy]

Is there an established method for testing output levels so i dont over drive the amps ?

If you're using the regular MiniDSP it is unlikely you'll overdrive any amp.

[kgveteran]

If you're using the regular MiniDSP it is unlikely you'll overdrive any amp.

Its the balanced version

[cjd]

My subs are humming like there is no tomorrow.... What to do. Cant lift grounds its a no-no. Do i run crazy grounds from everything that has none...

Good God Help Me hahahahahaha

A ground loop is created when you have multiple paths to ground. You can solve this by balancing them all exactly or by removing some... I.e. lifting ground. Just do it with care and you'll still leave the whole system properly grounded when hooked up.

[Hdale85]

Hmm as a fellow carpc/vst host person glad I saw this. I had debated before trying out a mini dsp or two in the car. Glad I didn't and will have to remember this.

There are some people running Mini-DSP's without hum issues. It's just something you may have to work on.

[kgveteran]

Seems a chassis ground to the outlet the power supply was plugged into did the trick.

The other subs that have plate amps with RCA inputs needed ground loop isolators.

[Shonver]

It's certainly not as powerful as some newer processors that have recently come out and coming out soon (at least for the car side of things), but they're pretty nice for what they cost.

What special features do those other processors have?

[Hdale85]

More processing power able to handle higher bitrates and what not. I can't list them off the top of my head but you can take a look at some of them, Audison BitOne, Zapco DSP-8, JBL MS-8, Mosconi 6to8, and there is also one from Arc coming out? Oh and the new Alpine H800 or something like that.

[kgveteran]

More processing power able to handle higher bitrates and what not. I can't list them off the top of my head but you can take a look at some of them, Audison BitOne, Zapco DSP-8, JBL MS-8, Mosconi 6to8, and there is also one from Arc coming out? Oh and the new Alpine H800 or something like that.

....but at 145.00 , thats a hell of a little processor !

[Hdale85]

Oh I didn't say it was a bad processor, just that some people in car setups had issues with noise.

[kgveteran]

Oh I didn't say it was a bad processor, just that some people in car setups had issues with noise.

I know for sure it didnt like to be powered without being grounded, Word !