[Bob in St. Louis]

http://www.hometheatershack.com/forums/spl-meters-mics-calibration-sound-cards/31380-ecm8000-phase-response.html

That makes my head spin.

[JohnR]

Someone needs to do the same measurement with a Behringer and an Earthworks and then see if we can compare the measured phase.

I suppose I could volunteer.

[Bob in St. Louis]

I suppose I could volunteer.

That would be great. Please let us know how things work out. 

Bob

[JDUBS]

I went from modded Behringer DCX2496 to DEQX 2.6P to DEQX 3.0 to Mac Mini with Pure Vinyl and a Metric Halo LIO-8 8-channel DAC.

This last setup is the best.  FuzzMeasure to do measurements with an Earthworks M30 mic (got a sweet deal on eBay) and Fabfilter to do crossover slopes (48db) and response modeling.

This is used with Yorkville Unity speakers which I pulled the passive crossover componentry out of and now (actively) triamp.  I can't go back to passive!!

Jim

[Tyson]

I said phase, but I meant Impulse Response.  Sorry!

[Russell Dawkins]

You can get something like one of the Dayton or Behringer mic, but they need to be calibrated for flat frequency response, but their phase response is off, and no calibration can fix that.

What does "off" mean in the context of impulse response?

[Pez]

So Tyson and I tried to do some EQ work on my system today, but circumstances were not kind and we ended up fighting with the software for the majority of the time. We finally got to a point where we were able to run some measurements and found that even though I have added room treatments galore that my general response was still damn good. We ended up making a few changes which ultimately didn't make the cut IMO. I ended up reverting back to my original settings.

It's hard to make these changes on the fly and always get great results, though I think given more time we can get things to sound even better.

My personal opinion, fix bass issues, level drivers appropriately and notch out a few problem areas. Once that's done make small adjustments in places. You cannot hope to fix massive bass nulls which everyone has. Nor should you be too nitpicky on other imperfections in your freq response.

[Bob in St. Louis]

Good words Pez.

[Tyson]

Agreed!  I find that the less EQ I apply in my setup, the better.  It measures better with more EQ, but usually sounds worse.  Same with crossover slopes - steep filters measure better, but I find I prefer the sound of shallow slopes.  I don't make these statements lightly, I've spent a lot of time and energy doing all sorts of experiments with this stuff in my system, both with closed boxes (the RM40's and the Ella's), and OB (the v2's).  My general rule of thumb is no more than 6db of EQ in the bass (and even then only cuts, not boosts), and only 3 db of EQ in the mids or highs.  The funny thing is that looking at Jason's crossover and EQ settings, our approaches are almost identical even though we arrived at them independently.

[Luigi]

Im sick to death of messing around with passive crossovers, but dont want to change too much of the rest of the system, which is what Id have to do with most balanced active crossovers. Until I was made aware of the miniDSPs.

Was about to pull the pin on a couple of two by fours when I saw a 2x8 system had been announced, so will probably end up going that way, and just getting a single unit.

There are a couple of good articles from a few years back on TNT-Audio about the evils of passive crossovers. They're illuminating and it makes you wonder why so many speaker makers continue to use them. Probably because they're cheap.

But increasingly it would appear active systems are becoming much more cost effective.

Guess the system complexity is the real stumbling block. You're not exactly dealing with amp, source and speakers hee. No-one in my house dare touches the stereo anymore, and I encourage them to use it, but even as a predominantly passive system it's all too difficult for them. Imagine how it's going to be once its all active.

Um, actually no different because they still wont dare go near it!

[Tyson]

The real beauty of active is that it lets you use more moderate amps on the mids/high and still get spectacular sound.  Of course, I still recommend using a monster SS amp on the bass..... So overall cost still stays low (more amps, but each one is less expensive).  But you are right, complexity increases.  But isn't that the fun of it?

[Pez]

What surprised me most about going active is just how little power you need to accomplish big things. Most people think the RM40s require a very powerful amplifier to run them and they would not be wrong about that. However once you eliminate the crossover you find that:
A. the woofers are always the power hungry culprit.
B. You can run the midrange panels with as little as 5 watts and get very very loud volumes without any ugliness. (tweeters with a watt or less!)
C. your speakers crossover (any passive speaker) is eating up watts just to run and the way it distributes power across each driver section reduces the power that amp can output drastically. What I mean by this is that the positive attributes of any amp tend to shine through even more with active and simultaneously the negative attributes of an amp are drastically reduced. Case in point using a low powered single ended triode amps on a speaker like the RM40 sounds like a really bad joke when talking about passive. But with active you suddenly have ALL the benefits people rave about when talking about SET sound and NONE of the drawbacks. No longer am I required to have uber efficient shouty horns or single driver setups in order to get that wonderful SET sound. No compromises on the type of equipment I WANT, no drawbacks, and lots of love. 

[Luigi]

Wouldnt mind hearing experiences of any miniDSP users here.

[Tyson]

Also, going active gives you control to indulge in your preferences to a degree not possible otherwise.  Personally, I like bass.  Especially with classical recordings.  So I can easily bump up the bottom for those recordings, and then back it down when I watch TV or a movie, or listen to jazz.  Speaking of Jazz, listening to early Louis or early Billie, dropping the treble a bit does wonders to make these very noisy old recordings more listenable and enjoyable.  Try THAT with a passive crossover!

[JohnR]

Wouldnt mind hearing experiences of any miniDSP users here.

Hi Luigi, I'm not sure if you've seen my miniDSP articles - http://www.hifizine.com/issues/minidsp-tutorials/

[Luigi]

Yes thanks John, read and reread those, lots.
Oddly, the part that worries me most is the fact I have only an iMac, no MacBook or laptop, and not sure what gear I will need for measurements.
I have an old AudioControl active bass crossover device (this proved singularly disappointing) which came with a microphone so perhaps the mike could be used for in-room measurements?

[bfr1992t]

The more you guys rant and rave about "going active", the more clearly my future direction is defined. A couple of mini-dsp's and class D's may be on their way soon.

I really need a suitable computer controlled volume control, that's been the major holdup.

[Bob in St. Louis]

"Hebrew Hammer" and "Blackmore" both use the miniDSP unit.
Last I heard, they rave about it.

Bob

[jimdgoulding]

For my size speakers and as compared with two way passives I've had in house over the years from Dynaudio, B&W, and Sonus Faber, dynamics are wider, bass goes deeper (-3db at 37Hz), more of one voice seems to me (they are time and phase aligned in the active crossvers and even include some DIP switches on the rear to tune the output to my room or taste), and musical.  It's a daunting thought to go back to passives with outboard amplification.  The internal (bi) amps, crossovers and speakers themselves are all designed by Bob Stuart of Meridian.

[JohnR]

Oddly, the part that worries me most is the fact I have only an iMac, no MacBook or laptop, and not sure what gear I will need for measurements.

I assume you can get it into the same room as the speakers? It's not actually essential but otherwise you'll end up with long cables.

You do need a reasonable mic, and a reasonable preamp. I like the USB interfaces, as it's just a single connection to my laptop, but I know others who prefer using a mic preamp and the line ins and outs on their computer. I think though that you need to factor in the cost of the measurement gear as part of your project, having tried to help a friend out who tried to do it on the cheap and ended up just wasting money...

The cheapest reasonable mic would be a calibrated Behringer or Dayton from Cross-Spectrum Labs. if you have a mate with a calibrated mic and can convince them to run a sweep with both mics you can make a calibration file by hand. - But it's hardly worth it unless you already have a mic. For the USB interface, I use a Roland UA25-EX, I think Tyson said he uses a M-Audio Mobile Pre, which is cheaper (and will work just as well for this purpose). Don't get a blue icicle - they don't work (well, the one I was asked to test didn't!)

I have an old AudioControl active bass crossover device (this proved singularly disappointing) which came with a microphone so perhaps the mike could be used for in-room measurements?

Hard to say. It could work, but I'd be inclined to just sell the whole thing, as I see frustration on that path. If you can post the actual model number we could try looking it up though.