Need advice - JBL 305P - DSP room correction - REW and DRC-FIR - results not that great

[asteroth]

Hi guys,

I have a pair of JBL 305P Mk2 for which I blocked the rear ports with socks. I am trying to improve their overall in-room response with DSP, because it's not that great.

I tried the following 2 paths:
- REW measurements + REW EQ + Equalizer APO
- REW impulse response measurement + DRC-FIR(https://drc-fir.sourceforge.net/) + Equalizer APO

One thing to mention, when I measured in room response with REW's sweep, it did 8 sweeps only for left channel, but for right channel it only did 1 sweep, then a crack/pop was heard and it stopped sending the signals for the rest of the sweeps. I tried multiple times, but for right channel it only did the first sweep, then the crack/pop then silence for the remaining seconds.

The microphone is a behringer ECM8000.

The problems are:

1. I'm not sure that I did the correct thing in any of the 2 paths I took
2. the DRC-FIR is awfully wrong for the left channel, the resulting EQ is bad and sounds really bad, but I don't understand why.
3. For REW EQ, the result doesn't sound hugely different than without EQ.

These are the commands I used for DRC-FIR:

ffmpeg -i L.wav -f f32le L.pcm
ffmpeg -i R.wav -f f32le R.pcm

drc --BCInFile=L.pcm --PSOutFile=L_filter.pcm normal-44.1.drc
drc --BCInFile=R.pcm --PSOutFile=R_filter.pcm normal-44.1.drc

ffmpeg -f f32le -ar 48000 -ac 1 -i L_filter.pcm L_filter.wav
ffmpeg -f f32le -ar 48000 -ac 1 -i R_filter.pcm R_filter.wav

Any suggestion is more than welcome.

I attached the in-room measurement files, the REW-EQ and the convolution files that DRC-FIR created.

 

[Mort]

Repost with an *.mdat

 

[asteroth]

Uploaded the .mdat

 

[asteroth]

I'm starting to think that this ECM8000 microphone is not functioning correctly.

I have it connected to a Behringer UMC204HD interface, with preamp gain set to max, and at normal listening level, I assume at least 55-60db in listening position, this is the recording that I get through this ECM8000 microphone. It's a very low signal, very low quality, barely any details in the recorded sound, and lots of microphone noise.

This is the wav recording: https://gofile.io/d/WbJLsX

Are you familiar with such microphones? Does this sound normal to you?
Heck, the phone's microphone is in another league compared to this ECM8000.

 

[respice finem]

Loose thought: The loudspeakers are not designed for the socks.
I would try again with their "factory state".

 

[asteroth]

Loose thought: The loudspeakers are not designed for the socks.
I would try again with their "factory state".

Do you have some technical background? Do you know what a Helmholtz resonator is?
Otherwise, your assumptions don't bring any value.

 

[DVDdoug]

I didn't look at your graphs..

I have a pair of JBL 305P Mk2 for which I blocked the rear ports with socks.

Did the socks make it sound better? That speaker has a pretty good reputation and I assume JBL knows what they are doing with the ports... There are lots of trade-offs and decisions in speaker design... You can make a good speaker with or without a port but once you've optimized the cabinet size and driver characteristics, and port dimensions (if there is a port)... it should be optimized.

But it is a tiny speaker so bass will be limited.

 

[respice finem]

Do you have some technical background? Do you know what a Helmholtz resonator is?
Otherwise, your assumptions don't bring any value.

If you know better (than the manufacturer) - good luck on your own.

 

[asteroth]

If you know better (than the manufacturer) - good luck on your own.

Please don't reply on subjects that you don't actually have knowledge. If you'd have checked those graphs you'd have seen that in room it has +15db peak at 50hz.
It's not that time consuming to check some graphs, you just import them here, if you don't have better tools at your disposal: autoeq.app

 

[asteroth]

I didn't look at your graphs..


Did the socks make it sound better? That speaker has a pretty good reputation and I assume JBL knows what they are doing with the ports... There are lots of trade-offs and decisions in speaker design... You can make a good speaker with or without a port but once you've optimized the cabinet size and driver characteristics, and port dimensions (if there is a port)... it should be optimized.

But it is a tiny speaker so bass will be limited.

Yes, they removed some of the excess bass.

 

[NotInYourHead]

Yes, they removed some of the excess bass.

These don't even look like the speakers are in the same room. I'd double check speaker placement and mic placement first and foremost.
Also I noticed the EQ settings extend into 10KHz+. Usually you want to avoid this, unless you have high quality measurements. Correct in-room response up to 1Khz at most IMO.

 

[Keith_W]

I'm starting to think that this ECM8000 microphone is not functioning correctly.

I have it connected to a Behringer UMC204HD interface, with preamp gain set to max, and at normal listening level, I assume at least 55-60db in listening position, this is the recording that I get through this ECM8000 microphone. It's a very low signal, very low quality, barely any details in the recorded sound, and lots of microphone noise.

I have two ECM8000's. Stupid question: did you turn on 48V phantom power?

These measurements of your L/R speaker look really unhealthy. I have never seen speaker measurements of "normal sounding" speakers look like that. Something is awry with your measurement setup. These measurements are uninterpretable, and 100% should not be used as basis of DSP correction.

What you need to do is diagnose the problem with your measurement. Your description of a popping sound followed by no sound makes me very concerned! Do you need help diagnosing your problem?

 

[Sokel]

Some DACs do the crack and stop thing at one channel, it's been known for ages.
Use WASAPI exclusive at the settings and keep DAC's level low-ish, if you want loud use your preamp for this.

 

[asteroth]

These don't even look like the speakers are in the same room. I'd double check speaker placement and mic placement first and foremost.
Also I noticed the EQ settings extend into 10KHz+. Usually you want to avoid this, unless you have high quality measurements. Correct in-room response up to 1Khz at most IMO.

The room is asymmetric. The left speaker is has the backwall 30cm away from the bass reflex port and the sidewall 45cm away. The right speaker has the backwall 30cm away and the sidewall is a few meters away.

I understand your advice, i'll limit the correction up to 1Khz.

 

[asteroth]

I have two ECM8000's. Stupid question: did you turn on 48V phantom power?

View attachment 505925

These measurements of your L/R speaker look really unhealthy. I have never seen speaker measurements of "normal sounding" speakers look like that. Something is awry with your measurement setup. These measurements are uninterpretable, and 100% should not be used as basis of DSP correction.

What you need to do is diagnose the problem with your measurement. Your description of a popping sound followed by no sound makes me very concerned! Do you need help diagnosing your problem?

Phantom power was turned on.
The popping sounds seems to be caused by the limited processing power of my laptop which has an Intel 6600U CPU.
Unfortunately, for the moment I don't have a stronger laptop to use for these measurements.

I've looked for a while into this issue that REW has with a pop/crack then sudden stop of the measurement and it's caused by the limited processing power. Funny that for left channel this doesn't happen.


I will perform the measurements again this evening.

 

[asteroth]

Some DACs do the crack and stop thing at one channel, it's been known for ages.
Use WASAPI exclusive at the settings and keep DAC's level low-ish, if you want loud use your preamp for this.

I will try to use WASAPI, but it's not a DAC issue, it seems to be an issue between REW + Hardware.

 

[Sokel]

I will try to use WASAPI, but it's not a DAC issue, it seems to be an issue between REW + Hardware.

Yes, it's the combination, not the DAC alone obviously.
I had the same at the dark ages of ESS9018+Amanero (me and many others) where Exclusive was not an option at REW.

What helped back then was reduced levels at the signal through REW, some -10dB lower than usual.
I read that these days Exclusive helps a lot.

 

[Keith_W]

@asteroth, I had a similar problem a few years ago when my microphone lost sensitivity and I could not obtain any decent measurements. One run would be OK, and the next I would lose a lot of microphone sensitivity. I had to turn the gain on the preamp all the way up.

I went bonkers trying to diagnose the problem. The problem had to be the microphone, the cable, or the interface. I tested the cable with a digital multimeter, and it was fine. I have three interfaces, and swapping interfaces did not improve the problem. So I bought another microphone, which is why I have two ECM8000's. Then the new mic had the same problem. So now I KNEW FOR SURE that it was the cable.

I was too cheap to buy an XLR cable of the proper length, so I made up a longer cable by plugging shorter cables together. It turned out that the connector of one of the cables was not manufactured properly. When I opened it up, I saw a strand of loose wire. Twist the connector a certain way, and it would short with another wire and send signal to the ground. As you can imagine, it was a real bitch to diagnose because of its intermittent nature. All that required was to snip off the loose strand and the problem went away. It would have been a $0 fix if I didn't have to spend money buying a microphone I didn't need.

 

[asteroth]

I have a PhD in acoustics, 25 years of experience in the field, and I lecture at a university. You didn't even send the MDAT of your measurement, put a sock in a port and pretended that was the way Ferdinand Von Helmholtz told you that was the right way, blamed JBL for a noise that the rest of us don't have and it's probably caused by an umbalanced connection, then blamed on Behringer that you don't know how to perform a measurement.

I wasn't talking to you, don't quote that as if I was talking to you.
You're the guy that started with a mean proverb and brought nothing useful to the discussion.
You can be the smartest person in the world, if you get in the room with mean coments, nothing useful, then you brag how smart you are and keep saying lies...how does it look?

Tell me more lies about that hiss...

https://www.reddit.com/r/audiophile/comments/acmi4e/fuck_jbl_and_their_new_hissing_305p_mkii

 

[Zinda]

Hi guys,

I have a pair of JBL 305P Mk2 for which I blocked the rear ports with socks. I am trying to improve their overall in-room response with DSP, because it's not that great.

I tried the following 2 paths:
- REW measurements + REW EQ + Equalizer APO
- REW impulse response measurement + DRC-FIR(https://drc-fir.sourceforge.net/) + Equalizer APO

One thing to mention, when I measured in room response with REW's sweep, it did 8 sweeps only for left channel, but for right channel it only did 1 sweep, then a crack/pop was heard and it stopped sending the signals for the rest of the sweeps. I tried multiple times, but for right channel it only did the first sweep, then the crack/pop then silence for the remaining seconds.

The microphone is a behringer ECM8000.

The problems are:

1. I'm not sure that I did the correct thing in any of the 2 paths I took
2. the DRC-FIR is awfully wrong for the left channel, the resulting EQ is bad and sounds really bad, but I don't understand why.
3. For REW EQ, the result doesn't sound hugely different than without EQ.

These are the commands I used for DRC-FIR:


Any suggestion is more than welcome.

I attached the in-room measurement files, the REW-EQ and the convolution files that DRC-FIR created.

You're not alone on bad test results using REW and that's if you can even get REW to run without errors. I used that same mic and external sound card to USB on my computer. I had nothing but errors and what's worse is when it did work I was seeing a nearly perfectly flat line . Other tests I used showed a real plot that had gain at 80hz, 200Hz and a dip at 1.25kHz . Those don't even show with REW. I didn't even bother going into other tests since it obviously was not accurate.

Adjusting my dual 31 band eq to compensate for results shown by test plots always sounds awful compared to just adjusting the 3 points I know exist from running working test programs and apps. I've tried 5 different DSP's and they too tried to tell me to do incorrect settings that were so far off from reality I could only laugh when I thought about how much time and money I wasted trying to use them.

Just awful interface on all DSP and computer programs for rta plot testing resulting in unusable results or lack of detailed results that did not correspond to the bands I was moving to get corrections. When I slide a 100Hz slider up I expect to see the RTA plot move 100Hz up at the same time and close to the same amount I moved it. Not in REW, I couldn't get it to show me anything that represented what I do, other free computer RTA tests could do it but they all lacked something that kept me from getting any real usable results. A few phone apps can trace my exact changes accurately and do it from 20Hz to 20kHz each movement of any band corresponds exactly. I can run a test on my phone with better accuracy and be done before my noisy computer is even ready to start running a program. Just a waste of time, sold the mic, use the interface for its bluetooth, computer stays off and is forgotten as an audio device.