PDA

View Full Version : PT800/PS1400 Crossover Question



maabx
11-04-2006, 08:17 AM
I am using these for two channel music. My amp is hooked to my music server (a Windows PC). I was preparing to measure my room response. I have a tone generator software and set up a sweep from 20Hz to 200Hz, 180 seconds. With a stopwatch in hand, I wanted to check the integration of the 14" sub with the 8" Ti mid bass driver. With a light touch on the 8" Ti driver's surround I can tell there is information below 80Hz getting to the mid bass driver. At around 60Hz, both the 14" bass driver and the 8" midbass driver feel as if they are equally active. The stack is set up normally supposedly using the 130Hz crossover point between bass and midbass drivers. Does this sound normal? I guess I figured that below 80Hz I would not detect any response from the 8" driver.

Thanks. Mike

Don C
11-04-2006, 04:06 PM
I don't think that you can judge much by feel. The lower driver is so much bigger, if it's moving as much as the smaller driver, it would be putting out a lot more volume.

maabx
11-04-2006, 06:56 PM
The point of the comparison was to convey the fact that the midbass unit was not slightly active, it was very active. I was asking if it was normal that the midbass unit was putting out at 60Hz.

Titanium Dome
11-04-2006, 07:16 PM
I don't think that you can judge much by feel. The lower driver is so much bigger, if it's moving as much as the smaller driver, it would be putting out a lot more volume.


Plus, beware of resonant vibrations. That 8" driver could be receiving no signal and still vibrate with the 14" driver's output at certain resonant frequencies.

Here's a post by Techbot that shows its Fs as 44.45Hz. Put it in a sealed enclosure of a certain size...

http://www.audioheritage.org/vbulletin/showpost.php?p=122169&postcount=4

maabx
11-04-2006, 07:49 PM
Okay, I tried it with the subs powered down. The midbass is still active at 60Hz. Maybe the high pass filter is not 100% effective. I was just wondering if it was normal.

maabx
11-04-2006, 07:59 PM
By the way, the speakers are magnificient. They are quite revealing, definitely capable of exposing any weaknesses in equipment and recordings. They are easily a step up from my S310II's. I loved the S310II's but I could always 'hear' the paper. Paper is great, but it gives off an unmistakable slight coloration. They are way better than my SVA 1600's.

maabx
11-05-2006, 06:42 AM
Okay, per Giskard:

"6 dB / octave 130 Hz high pass to the PT800 when selected in the PS1400

12 db / octave 20 Hz high pass in the PS1400 (always on)

18 dB /octave 130 Hz or 300 Hz low pass in the PS1400 (must select one or the other)"

So 6 db per octave is a gradual rolloff. This means that at high SPL's, say 112 db, there will be lots of information going to the 8" Ti driver below 80Hz. Like 100 db at 32.5Hz. Is this correct?