MiniDSP - Page 34

If you are running the SW Out from your pre/pro or AVR to the amp that powers your subs, why would you need this MiniDSP? Just curious. I think it's an awesome product, but seems unecessary in most HT applications, especially with AVRs having software like Audessey (sp?) already built in. Sorry for the derail; just curious.

Well, apart from it's intended purpose as a electronic crossover, it makes a great HP filter to protect vented subs from frequencies below their tuning.

For me, i have to EQ the main sealed subs due to their 12db/Oct rolloff which begins around 38hz.

Then EQ the two AUX subs with Hipass and Lopass and PEQ if needed, along with phase inversion if needed and level....

For 145.00 a steal

Good point, Theresa. But most pre/pros/AVRs have subsonic filters built in. Though not all offer the adjustability of the MiniDSP. I guess for "utlimate tweakability", which is what DIY is really about, the MiniDSP fits the bill.

Though if you've already got a filtered signal from your AVR, further filtering could throw the signal out of phase and create other issues. I'm not real smart on this stuff, but smart enough for questions to pop up, I guess.

I run my Denon 3803's SW out into a SVS PB12+. That's enough for me. Though I do drool and dream of having four 18's across the front of my imaginary, dedicated HT room. Now i have to move my kids' toys off the sub before I fire it up so they don't become projectiles.

Ah, I forgot that many here run "hi subs" and "ULF subs" I can see where this thing would come in handy. See? That's why I love this place; I get educated in two minutes flat.

Well, I hope that there aren't many receivers/pre-pros that have an internal High Pass filter on the sub outs, its something that needs configuring depending on the characteristics of the driver and box.

Those of us with tapped horns subs need to pre-flatten the response, as variations are outside the boost/cut limits of Audyssey et al.


Which ones?

The only one I had that did was an HK 635, which I believe had a lowest setting of 15 Hz.

Which would actually be too high for some people these days.

Yeah, only reason i bandpassed my AUX subs, was to fill in the null at the LP. Most of the time Hipass is a no-no, especially sealed.

I was amazed at the cabin gain in my room, it made it easier to add a shelf filter....

Why is this? I think Not uses a high pass for his sealed LMS 5400s and recommended I do the same for mine.

I use a 10hz HP since the LG clones have enough power to bottom out two 5400's.

I forgot that some still use sealed subs but sealed do not have the need for HPF that vented ones do.

You are the second person to state a HPF is not needed for sealed subs, but no explanation as to why. I have two sealed LMS 5400s and they both bottom out on HTTYD running off a single QSC RMX 5050. This make me wonder if there is something wrong with my setup and I just spent money on a MiniDSP for nothing.

Has anyone ever used these http://amphony.com/products/a100.htm along with a miniDSP for an active setup.

Price seems right but I don't want to blindly purchase, particularly since this will be my first active rig.

The idea that a highpass is not beneficial on many sealed subs is ridiculous. They do not suffer the same uncontrolled cone motion below tuning that ported do, but with a large low Q enclosure it is easily possible to exceed Xmax (distortion) and Xmech (damage) with easily available amps. This is especially true with EQ applied such as an LT.

Same thing happened to Notnyt, which is why he turned the HPF on.

If you have enough power to bottom out the subs below 20hz, you need a HPF.

Besides simple protection, HP can be used to trade extension for more output in the remaining passband, both from not using up excursion at low freq and not spending amp power on them.

But with sealed it's not as clearly defined where the HP should be. The excursion may continue to increase towards DC, but in a controlled manner (unless eq has changed this). So it may be so that a sealed sub experiences over excursion at some frequency, it shouldn't suddenly lose control below some tuning point. If so, then a very low order (1st or 2nd) HP could be used, unlike a ported design which may need something higher order (3rd or 4th).

My LMS 5400s sure don't. In HTTYD they bottom out quite easily with a sickening crack at slightly above medium volumes during the giant dragon crash scene. They are in ~3.5 ft^3 sealed boxes and both are being powered by a single QSC RMX 5050 at the moment. The amp is not clipping at the time. Same happens while using a Behringer EPX4000. The level meter is not going all the way up on either channel when it happens. I can see the surround on the drivers deforming when it bottoms out.

I dont Hipass because using 3 cubic feet limits excursion. Plus, they never gave it up during those scene's. My room is only 1800cubic feet, it doesnt take alot of output to excite the room.

Interesting enough, if i hipass the AUX subs with no Lopass i have to invert phase. If i hipass and Lopass the AUX subs i leave the phase alone.

I'm hoping tweaking these 12's will yield a worthwhile sound i can live with.

After my subs were setup using the Mini, i EQ'd with Audyssey. My subs came up -6db. I want to get them to 0db so i have more room to raise and lower.

What control would raise and lower all three subs to lower their output as a system on the Mini

Duc, I think you've misunderstood what I said. During playback it might happen suddenly, but a controlled xcursion doesn't require an abrupt HP.

Edit - and if you've eq'ed in a way that cause abrupt excursion, this doesn't apply.

Um post #1010 please

Maybe I am misunderstanding what you are trying to do but wouldn't you just click on "Input Gain" then lower the "Input channel level" by the 6db?

Moto

Yup, that would do it, just wasnt sure, thanx

I just bought a Rythmik FV15HP which needs 0.3VRMS to drive the amp to full power. Is it best to use the minidsp rev A or rev B with this sub?

My technical reason for thinking rev A is correct is because .9 is closer to .3 than 2.0 is. Pretty clever huh?

I believe the difference between A and B is the input sensitivity, which is a factor of your source, not the amp the mini is outputting to.

In any case, either can be changed with the jumper inside, so the choice you make isn't permanent.

Output voltage is the same on both. If you still find you're attenuating too much in the digital domain, a pair of resistors to make a voltage divider to drop the level into the plate amp is easy and about $1 in parts.

Get the balanced version.

I'd actually say unbalanced, just because then he can run standard RCA wires, rather than cutting up wires and wiring up the Phoenix terminals.

Anyone else get an 8x8 in a box?

Oh, i thought everyone liked cutting, chopping ect