[JohnR]

So whats fixable with EQ and what will I have to wait for my second and third subs for?  I imagine that huge hump below 60hr will have to wait.

If you take some spaced measurements around the listening spot I suspect you will find that the curves are fairly similar up to maybe 100 Hz (making a guess on room size based on where those lower peaks are). For example, here's one of mine, with the mic moved 30cm left and right (this is post-eq but you get the idea about the nature of the variation caused by mic position):



My inclination would be to turn off the mains and the sub crossover and eq the sub flat (across the chosen area around the target listening position) and then re-integrate. That would give a reference to compare against when you get multiple subs set up.

[sts9fan]

Thanks guys.   I plan on doing just the sub today.  That was just a test to see where I was at. 

[BobRex]

Please tell me that the Y scale is off and that you really weren't measuring at 120+dB. 

[sts9fan]

You are correct

[sts9fan]

I was able to screw around with the MiniDSP this morning for an hour or so.  Here is what I was able to get.  I did move my sub from the front left corner to between the speakers which are 2-3' out from the front wall.  I also put a GIK 244 across the corner where the sub was.





Not too bad for an hours work.

[stereocilia]

That does look good.  So, what's next?  Drop 4.5 K a few dB?  Does it sound less punchy without the bass peak?

[sts9fan]

I am not filtering the mains at all.  The MiniDSP input was overloading (theory) from the output of my pre.  My amp is low gain (13db) so I need the active pre.  If I turn it all the way up it still does not clip the amp with my vinyl source.  Plus I generally don't want to pass the mains signal through this device. 

[stereocilia]

I see.  Maybe you could try the mini dsp before the preamp by turning down the gain on your DAC and running the (unattenuated) analog output of the squeezebox directly into the preamp.  Of course, you lose the benefit of the better-sounding DAC but it might prove your overload theory.

[stereocilia]

...that doesn't help with vinyl, I realize.  A passive line stage before the mini DSP might work if the previous thing pans out.

[sts9fan]

I have attached the mini to the second outputs of my pre with a pair of F-Mod 12db attenuators to the sub.  The mains do not go through the mini.  Seems ok, although I am going through a system "time" so its hard to tell. 

[stereocilia]

gotcha.  It feels wrong to turn the signal up, then down, then up again, but as they say, "whatever it takes to make the dirt stick."   I'm sure you'll get 'er dialed in. 

[sts9fan]

Don't make me feel worse about it.  I think I am gonna sell everything and get a reciever...

[stereocilia]

I wasn't trying to make you feel worse.  That said, Pioneer does make some sweet receivers.  You can pick one up used for like $200 that will wail on any separates. 

Seriously, though, I just meant to comment that it takes an unanticipated extra step to get the desired result.  Is there anything undesired about the result?  It looks pretty good on paper.

On the subject of measurements, the question of which frequency response target is best is interesting.  The easy answer is "flat," but is that true at every volume level for every system?   I don't know.

It happens in the world of hearing aid fitting, but there are more variables.  For instance, the NAL (National Acoustics Laboratory -- of Australia) has traditionally set the standard for prescribing the frequency response of a hearing aid for a given audiogram.  But, there are competing strategies that come up with very different right answers, like the DSL (Desired Sensation Level -- from Canada) formula, for instance.

sorry.  I got a little off topic.  I would be interested to see if the response changes with volume, or if it changes between using a pure-tone sweep or a broad-band signal.  Ideally it wouldn't but not many people check for linearity.   The "soundstage" website speaker reviews ususally do, but I haven't seen it otherwise.

You could also play one frequency and measure at an octave higher (if the software allows) to measure harmonic distortion.  ...all kinds of cool stuff could be done.

[JohnR]

I was able to screw around with the MiniDSP this morning for an hour or so.  Here is what I was able to get.  I did move my sub from the front left corner to between the speakers which are 2-3' out from the front wall.  I also put a GIK 244 across the corner where the sub was.

What are the main speakers here?

[sts9fan]

Gedlee Nathans

[JohnR]

Interesting. I wonder what's causing the bump in the 4-5k area. The in-room response dips just over 1k, is that the crossover frequency?

Are you using a lowpass filter on the sub? It's going up pretty high.

[sts9fan]

I have a 48db cut low pass at 120hz.  I am still playing around.