[mfsoa]

While I have Wolfy's SP Tech Timepiece 2.0s here I thought it'd be fun to run the bass section of the Stereophile test cd through 'em, and then through my Von Schweickert VR4JRs.
Quick details: Rotel CD -- Superphon -- Channel Island D200 -- right speaker only, pointing at rt shoulder of listener.
Meter located at listening position. TPs were measured first. Then TP was removed from the room and the VSR put as closely in the same place as possible. Same preamp volume position for each speaker. C weighted, slow response.

The readings were very repeatable and seem to show the bass prominence that I heard with the TPs in my room. It's not an unpleasant effect but it feels like your Fletcher-Munson curve is getting fully tweaked before the overall volume is really high:

For whatever it may be worth:

[mcullinan]

Mike,
what's it mean in laymans terms? I see dots & numbers....
great rave and I really enjoy the rave disk you made.
thanks.
mike

[Bill Baker]

Interesting results but I think there is one flaw in the test. You mention the same "preamp volume postion". I think a more accurate way to compare would be to get a reference with a 1kHz tone on each speaker before testing to assure both speakers are being played at the same level rather than the same volume positioning.

[mfsoa]

Bill,
I agree but I did it this way first to get a sense of the sensitivity of each speaker. It turns out that the average levels were close enough that I didn't do a level-matched re-run.

-Mike

[zybar]

Mike,

One other factor that skews the results is the fact that you tried to put both speakers in the same location vs. the optimal placement for each.  Since each speaker is very different, putting them in the same location is not a good idea.  Each will load the room differently and have a place where it will sound best.

Also, as Bill pointed out, you really have to have both pairs of speakers level matched.  Close, really isn't good enough.

Lastly, any decent measurements (especially in the bass area) really can't be gotten by using the Stereophile test cd.  You need to use more than a 1/6 octave test sounds.  You need much finer spacing between test tones to really see your true peaks and valleys.  Check out this on RealTraps.com:

http://www.realtraps.com/test-cd.htm

Not trying to bring you down, but unfortunately, there is much more to this than the test you did.

George

[Aether Audio]

mfsoa,

There's 2 ways to look at your graph there.  Besides the facts that Bill and George have pointed out, let's just assume for the moment that you achieved reasonably accurate results.  The biggest caveat in a non-gated measurement (such as what you have taken or that from a real-time analyzer/pink noise measurement) is that it is "time blind."  You can't see what's going on in the time domain.  If you have a room resonance (most likely) at that frequency your measurement could be reflecting that you are experiencing an anti-phase node at the measurement location as much as you are a peak at the low end.

Rather than saying you have a "peak" in the 50Hz region, you could just as easily say you have a partial "null" in the response centered somewhere around 70 to 80 Hz.  Or... possibly (no doubt in my mind) both are going on.  I can tell you this much...it's not physically possible for the Timepiece's single woofer to produce  a response curve like that - at least not in an an-echoic environment.  It behaves as a perfect piston and a little research will show that a piston simply can't behave like that.  OK... I guess it could if the enclosure volume were grossly over-sized for the driver and the free-air resonance of that driver was located near the peak you've measured.  In this case that's definitely not the case as that driver's free-air resonance is 23Hz and the box is tuned to 29Hz.

So... actually you have a dip and a peak from the looks of it to me.  If you look at the average response, it's centered at about 75 dB.  Then look at the peak at the low end - closer to 40 Hz.  Then the dip looks like it's almost exactly at 80 Hz.  Then the next peak is almost right on 120Hz.  See a trend?  Multiples of 40 Hz.  You have a primary mode at 40Hz with nodes and anti-nodes at harmonic intervals.  This one was easy.

Now, look at where the woofers are on the VSs vs. the woof on the TPs with regards to height from the floor.  Repeat the test.  Set the TPs on the floor...not on the stands this time...and see what you get. 

Yep, that's an engineering compromise.   The TPs are a 2-way so for proper dispersion you have to have the woofer near the tweeter and the tweeter needs to be somewhere near ear height.  Soo...we can't put the woofer near the first reflection boundary (the floor) unless we don't mind a very "low to the floor" tweeter.   Try moving the TPs around a little, you might be able to minimize if not completely eliminate the problem.  Otherwise, that's why God invented "room treatments."

Have fun and good luck!

-Bob