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Multi-Way Conventional loudspeakers with crossovers

JBL LSR305 tweaking
JBL LSR305 tweaking
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Old 19th March 2018, 10:14 AM   #21
Dmitry M is offline Dmitry M  Russian Federation
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Quote:
Originally Posted by Juhazi View Post
My -25dB is "worst scenario", the cabinet's back wall was opened, cavity working as an amplifier in the measurement. But still, with music the fixed speaker sounds much better than original!
Thank you for the report.
But I'm doubt that transverse bracing really helps. Because the driver not contacted with wooden part of cabinet and screwed to the plastic face plate only. I think the good idea of modding would be attaching the driver to wooden part of cabinet by any kind of glue may be... Or to glue a brace between plastic faceplate and cabinet?

Quote:
Originally Posted by DPH View Post
Anyone sealed the vent (aperiodic, aka, a sock or 3, or completely closed off) and then run them with a sub? 6L6 is that what you're doing? Seems like they'd do a whole load better.
If you apply JBL's sub LSR310s the sub will cut signal below 80hz from monitors (see manual). So no need to seal the vent

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Originally Posted by xrk971 View Post
I had to return them because could not sound anywhere near as good as my FAST with 10F/RS225. But what bothered me was that despite being internally DSP’d - the response was not flat.
This file will make LSR305 transient perfect when playing from Foobar.
Download "convolver" for Foobar and put this file "FIR.wav" to it.

After that 305's will play meander and will have ideal Step response when playing from Foobar.
Attached Files
File Type: zip FIR.zip (142.3 KB, 30 views)
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Old 19th March 2018, 12:21 PM   #22
xrk971 is offline xrk971  United States
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JBL LSR305 tweaking
I did not have peaky distortion rattle on the LSR305’s I measured but a broad hump - looks like panel resonances which dominate though. The 3rd harmonic from 200hz to 600Hz is especially troubling.

lsr305-hd.png

It was a bit disappointing considering all the rave 5 star reviews I read prior to buying them. Also, the published response was flat - not waivering like this.

Anyhow, even at $210/pair I did not think they were worth it. The mid bass was lacking presence and sound was just not clean enough I ended up returning them. The value would have been incredible had they sounded good. But IMO, a well designed passive 2-way with a solid cabinet and decent but budget drivers sound better.

Certainly, the GR Research XL’s are superior in flatness of response and distortion. Just missing the waveguide.
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Last edited by xrk971; 19th March 2018 at 12:32 PM.
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Old 19th March 2018, 12:47 PM   #23
manninen is offline manninen  Finland
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How is the phase curve in LSR305?
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Old 19th March 2018, 01:20 PM   #24
TBTL is offline TBTL  Germany
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Phase can be approximately derived from amplitude response + the known crossover frequency. If you EQ the amplitude response to flat, you end up with an all pass filter at the crossover frequency.
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Old 19th March 2018, 01:36 PM   #25
manninen is offline manninen  Finland
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Yeah that might be it on this speaker, something 4th order i´ll bet.

Haven´t study much how the phase should look when mid/high timing changes on these xo´s, im more familiar with flatter phase speakers

Last edited by manninen; 19th March 2018 at 01:39 PM.
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Old 19th March 2018, 01:46 PM   #26
kimmosto is offline kimmosto  Finland
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JBL_LSR305_VCAD-QC.png
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Old 19th March 2018, 01:48 PM   #27
manninen is offline manninen  Finland
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oh yeah!! could need some delay between high/mid. or some cases turn it upsidedown

Last edited by manninen; 19th March 2018 at 01:51 PM.
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Old 19th March 2018, 02:03 PM   #28
Juhazi is offline Juhazi  Finland
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xrk, obviously our speakers were faulty units, something loose inside? My measurements line up with noaudiophile well.

Dimitry, the amplifier board takes whole backwall, it is impossible to connect front and backplate together. Sidewalls cover wide area and are homogenous and flat, so the best possible benefit from bracing comes that way, and it is easy because backwall can be screwed off.

kimmosto,what do you think is causing that wiggle in directivity xo ? Xo is LR4 @1700Hz

Here some more of my reasurements before and after tweaking. All done quick and dirty in mancave, mic held by hand and angles estimated visually.
Attached Images
File Type: jpg LSR305fix 0-45¤ 5ms 112.jpg (121.4 KB, 419 views)
File Type: jpg LSR305fix 0-45¤ 20ms 16.jpg (124.6 KB, 396 views)
File Type: jpg LSR305 0-45¤ 5ms 112.jpg (122.2 KB, 390 views)
File Type: jpg LSR305 0-45¤ 20ms 16.jpg (124.1 KB, 269 views)
File Type: jpg LSR305 w port near 200ms nosmo.jpg (118.0 KB, 273 views)
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Old 19th March 2018, 02:15 PM   #29
kimmosto is offline kimmosto  Finland
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Quote:
Originally Posted by Juhazi View Post
kimmosto,what do you think is causing that wiggle in directivity xo ?
There's no wiggle in directivity - other than vertical lobing of two separate sources. Response shape around XO freq is global in horizontal plane. Note that directivity charts are not normalized.
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Old 19th March 2018, 03:12 PM   #30
Dmitry M is offline Dmitry M  Russian Federation
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Here is my measurement in room.
Approximatelly 80cm
mic uncalibrated Nady CM100
Attached Images
File Type: jpg IMG_0202.JPG (266.5 KB, 225 views)
File Type: jpg IMG_0203.JPG (318.1 KB, 224 views)
File Type: jpg IMG_0204.JPG (200.2 KB, 218 views)
File Type: jpg IMG_0205.JPG (311.1 KB, 211 views)
File Type: jpg IMG_0206.JPG (265.9 KB, 211 views)
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