Home » Sponsored » Pi Speakers » 7Pi Build 2014 (7Pi Build 2014)
Re: 7Pi Build 2014 [message #80623 is a reply to message #80622] Sat, 04 October 2014 13:52 Go to previous messageGo to next message
skywave-rider is currently offline  skywave-rider
Messages: 104
Registered: May 2009
Viscount
Is this a measurement of one speaker, the other muted? Pease give the measurement details, equipment, distance, etc..
Re: 7Pi Build 2014 [message #80624 is a reply to message #80623] Sat, 04 October 2014 14:15 Go to previous messageGo to next message
compaddict is currently offline  compaddict
Messages: 73
Registered: April 2014
Location: Auburn, CA USA
Viscount
Both speaker driven, 14 feet from each, MIC at listening level, Behringer MIC800 and preamp. Yamaha RX-A840 and Outlaw 2200 mono amps.
Yamaha set flat.
Re: 7Pi Build 2014 [message #80626 is a reply to message #80622] Sun, 05 October 2014 08:51 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 17446
Registered: January 2001
Illuminati (33rd Degree)

If the measurements are right, it looks to me like there are at least three things happening.

First is the midrange doesn't look attenuated to match the other drivers. So I would look at the R4/R5 resistors. Make sure they're installed correctly and not shorted. That's a kind of easy problem to solve because it's just attenuation.

Second, the 300Hz peak. Something is going on there, probably a panel resonance. You might want to damp panels one at a time with a pillow or your hand and see if you can identify the cause. That one could be a measuring artifact too, so move the speakers and microphone and measure again. Best to measure outside. But I suspect that one is a panel resonance.

Third, the lack of treble, and the overall downward sloping trend. I see that a lot with measurement problems. Sometimes I see it with microphones overdriving the input amplifier. One would think the extra harmonics would artificially show excess HF, but I often see that problem cause a downward slope. Or it could be something else in the measurement system. But this could be confirmed by measuring something else and seeing if the downward trend existed there too. If it's truly the speakers, then the tweeter circuit or compression driver is off.

Re: 7Pi Build 2014 [message #80627 is a reply to message #80626] Sun, 05 October 2014 10:53 Go to previous messageGo to next message
compaddict is currently offline  compaddict
Messages: 73
Registered: April 2014
Location: Auburn, CA USA
Viscount
The 300 peak was a bad SC cal file. Disregard.
Re: 7Pi Build 2014 [message #80629 is a reply to message #80113] Sun, 05 October 2014 16:52 Go to previous messageGo to next message
compaddict is currently offline  compaddict
Messages: 73
Registered: April 2014
Location: Auburn, CA USA
Viscount
http://ge.tt/3ko77f02/v/1?c

Whole set of new files with corrected SC file.
Both speakers tested 1M and flat as well as some B&W DM 330 cheapies for reference.
Re: 7Pi Build 2014 [message #80630 is a reply to message #80629] Mon, 06 October 2014 08:37 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 17446
Registered: January 2001
Illuminati (33rd Degree)

I didn't find any image files in your archive, so I can't see your response curves. I run WTPro and LMS, so the REW data files aren't useful for me. But even if there is no real 300Hz anomaly, there is still something way off. The midrange is much higher than the treble, telling me either the compression driver or the crossover is at fault. If you would like, send the crossovers to me and I'll check them out. We'll get to the bottom of it.

Re: 7Pi Build 2014 [message #80636 is a reply to message #80113] Mon, 06 October 2014 12:12 Go to previous messageGo to next message
compaddict is currently offline  compaddict
Messages: 73
Registered: April 2014
Location: Auburn, CA USA
Viscount
http://ge.tt/3ko77f02?c
Whole set of new files with corrected SC file.
Both speakers tested 1M and flat as well as some B&W DM 330 cheapies for reference.
Two files renamed for clarity.
REW is the SW used.
Re: 7Pi Build 2014 [message #80637 is a reply to message #80636] Mon, 06 October 2014 14:00 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 17446
Registered: January 2001
Illuminati (33rd Degree)

Again, we see that there is a huge rolloff up high. It looks like the compression driver tweeter isn't even connected. That's where we need to focus, I think. Concentrate on what may be causing the lack of HF output, whether it be bad crossover, wiring or compression driver.

Re: 7Pi Build 2014 [message #80638 is a reply to message #80113] Mon, 06 October 2014 14:01 Go to previous messageGo to next message
JCDC is currently offline  JCDC
Messages: 43
Registered: August 2010
Baron
I think he played them without the extra (or any?) front gaskets.

Could the driver 'bottom' in such a situation? And then affect freq resp?
Re: 7Pi Build 2014 [message #80639 is a reply to message #80638] Mon, 06 October 2014 14:09 Go to previous messageGo to previous message
Wayne Parham is currently offline  Wayne Parham
Messages: 17446
Registered: January 2001
Illuminati (33rd Degree)

JCDC wrote on Mon, 06 October 2014 14:01
I think he played them without the extra (or any?) front gaskets.

Could the driver 'bottom' in such a situation? And then affect freq resp?

The midhorn gaskets aren't needed unless output is really high. And by "high" - I mean way past the level anyone would feel comfortable listening.

If pushed that hard, then the driver is pushed past its limits. One can go past xmax with those drivers without damage, but the sound quality plummets. So for hifi applications, an extra gasket isn't needed.

Besides, what we're seeing is a lack of HF content. I think that's where we need to concentrate.

At first, I thought we might have some sort of midhorn panel resonance because initial reports were that voices sounded distorted. I didn't even think the crossover was suspect, because I thought we were dealing with a buzz or something like that.

But after seeing measurements, I think just the opposite. I now think the problem is the compression driver or tweeter circuit. Measurements are showing that there just isn't any tweeter output.

Previous Topic: Amp for 4pi speakers
Next Topic: Best Amps for 3Pi
Goto Forum:
  


Current Time: Sun May 19 02:29:43 CDT 2019

Sponsoring Organizations

DIY Audio Projects
DIY Audio Projects
OddWatt Audio
OddWatt Audio
Pi Speakers
Pi Speakers
Prosound Shootout
Prosound Shootout
Smith & Larson Audio
Smith & Larson Audio
Tubes For Amps
TubesForAmps.com

Lone Star Audiofest