I would say that he is not measuring the type of distortion that he's hearing, which would be equivalent to IMD of the relatively low level high frequency information in the recording - something that standard THD measurements would not pick up. I would suggest that he lowers the volume level so that he could listen, comfortably, "a few inches from the driver" - think, headphone listening ... does it still sound "fizzy"? And continue in that vein ...
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JBL LSR 308 in the house
- Thread starter RayDunzl
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OP
- Thread Starter
- #62
Ultra-Nearfield - Red - 6 inches or so - and listening position - Green - 10 feet - unsmoothed of the left JBL:
It's room interaction, not speaker.
Compare:
JBL Ultra-Nearfield - Red - 6 inches or so - and listening position - Blue - 10 feet - unsmoothed of the left ML:
It's room interaction, not speaker.
Compare:
JBL Ultra-Nearfield - Red - 6 inches or so - and listening position - Blue - 10 feet - unsmoothed of the left ML:
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OP
- Thread Starter
- #63
There is a slight broadband hiss measurable close to the speaker, shown earlier, doesn't seem to be correlated with the dips. Not measureable from the listening position, it's below the noise floor.
Distortion: Correct, higher by 10dB or so, at the listening position, like -40/-50dB instead of -50/-60dB with the panels.
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OP
- Thread Starter
- #64
I did some dual-tone measurements, the results were very similar between the JBl and ML, so much so that I didn't see that as a difference.
Blumlein 88
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Thanks for the measurements Ray. Just noticed you could go wireless on your subs.
http://www.parts-express.com/dayton...itter-receiver-system-for-subwoofers--300-580
Those might be useful if they work well. You wonder about them at $69.
OP
- Thread Starter
- #66
I have one, haven't used it with the subs as I still have them in "stereo", repurposed it to send what I was listening to in this room to Mother's sidewall-adjacent room.
It isn't bandwidth restricted that I notice causally - not for subs only or anything.
Muffled boom from behind the wall didn't seem nice to subject her to, so I fixed her up with the Infinity P-363 run off an old Pioneer SX-780 with the receiver attached to an input to disguise my noise with the actual program when we got too loud on Beer Saturdays.
Unfortunately its range isn't quite enough to get out to the garage or the main bedroom. I haven't experimented beyond "didn't work".
It was a $20 (or $40, I forget) add-on when buying the subs, so I took that chance.
It isn't bandwidth restricted that I notice causally - not for subs only or anything.
Muffled boom from behind the wall didn't seem nice to subject her to, so I fixed her up with the Infinity P-363 run off an old Pioneer SX-780 with the receiver attached to an input to disguise my noise with the actual program when we got too loud on Beer Saturdays.
Unfortunately its range isn't quite enough to get out to the garage or the main bedroom. I haven't experimented beyond "didn't work".
It was a $20 (or $40, I forget) add-on when buying the subs, so I took that chance.
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With conventional dual tonemeasuring, the levels of the tones would be comparable - I would be interested in what happens when the higher tone is much lower in amplitude than the lower, say 40dB down - what happens to the distortion spectrum directly related to the higher frequency, as the amplitude of the lower frequency varies.
What this could tell one is how much the variable current draw on the PS, in the JBLs, is impacting the distortion behaviour.
Blumlein 88
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You are talking about the old SMPTE standard. 60 hz with 7 khz. With 60 hz being in a 4 to 1 ratio with the 7 khz to see if distortion of the 7 khz is modulated by the 60 hz tone. Then again, I would expect the class D switching amps in these using switching supplies aren't effected by the 60 hz so much.
OP
- Thread Starter
- #69
Somewhat incredibly to my antique eyes, this chip turns out to be the 2 x 50W "amplifier" in the 30x Series
STA350BW
http://rdimitrov.twistedsanity.net/blog/show.php?entry=JBL LSR305 Teardown and Analysis
STA350BW
http://rdimitrov.twistedsanity.net/blog/show.php?entry=JBL LSR305 Teardown and Analysis
watchnerd
Grand Contributor
What software are you using?
All I can tell is that it's Windows-based and looks to run in Java.
Also would be curious to know what mic.
OP
- Thread Starter
- #71
Room EQ Wizard (free) and MiniDSP UMIK-1 ($100 or so when shipped)
DSP is MiniDSP OpenDRC-DI - $325 + shipping
DRC is AcourateDRC - $80 Euro + VAT if required
DSP is MiniDSP OpenDRC-DI - $325 + shipping
DRC is AcourateDRC - $80 Euro + VAT if required
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watchnerd
Grand Contributor
I thought it was probably REW -- but I use it on the Mac, so it looks a bit different.
I also have the MiniDSP + UMIK, too.
OP
- Thread Starter
- #73
Well, you're all set.
Go measure something and post it.
Go measure something and post it.
The chip shows borderline acceptable distortion figures, by audiophile standards - and they're not game to show figures for any frequency above 1kHz! I can't complain, because the class AB chip amp in my lowly Philips HT box showed poor figures too - yet delivered impressive subjective performance at times. However, may be the cause of the fizziness, in this case ...
I find it interesting how much "scrutinizing" is being done on such a inexpensive product.
Kind of shakes the timbers of the High End
I also have the same gear as do many others.
How about doing a tutorial on doing some of these basic measurements you post
Amir did a basic step-up tutorial of REW but the promised followup still await.
http://audiosciencereview.com/forum...om-measurement-tutorial-for-dummies-part-1.4/
I find the REW help files a bit (lot) confusing and hard to follow.
Thanks Sal for the reminder. I will try to get that done soon.
OP
- Thread Starter
- #78
Well, you're all set.
Go measure something and post it.
Start a WTF Am I Doing? thread.
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