JBL 705P Studio Monitor Review

[amirm]

Is this due to your measurement being higher resolution?

To some extent yes. At the high frequencies though, there is a bit of comb filtering in my rig which I can get rid of by eliminating the mic protection cage. But I prefer to not chance it.

 

[amirm]

Does a factory reset load the "flat" factory preset, or is that an additional step?

Additional step. I did what you post but didn't get rid of the EQ.

 

[spacevector]

To some extent yes. At the high frequencies though, there is a bit of comb filtering in my rig which I can get rid of by eliminating the mic protection cage. But I prefer to not chance it.

Didn't you figure out some padding stuff for that? I remember reading something to that effect.

 

[Deleted member 2944]

One of the three speakers has noticeable hiss. That one's going back.
With a long AES run (like 25' per cable) I get no sound from the FIRST speaker in the chain. The second still plays. A shorter cable between the speakers solves the issue. Never had this problem with the 708p. Obviously the first speaker gets the signal, so I'm not sure why it fails that way.

I suspect this is a termination issue when chaining multiple (greater than two) speakers.

The JBL 70XP speakers don't properly configure a termination scheme where the last speaker (and only that speaker) has the proper 110 ohm AES terminator.
Each speaker has its own 110 ohm terminator and if you continue adding speakers via the feed-through jacks, the parallel combination continues to further load the source. This seems to work okay for two speakers, but when you start adding third/fourth/etc, you will run into a problem.
I fail to understand how they messed this one up.

The proper way to do it would be as the Dutch & Dutch folks have. You have a portable 110 ohm XLR connector that plugs to the feed-through jack on the final speaker. Since the speakers themselves do not have a termination internal this scheme works correctly.

This is not unlike an old 10-base-2 ethernet system or the CAN Bus in your car. Chaining multiple devices works well as long as you terminate at the last device and don't have any "stubs" along the way that can cause reflections.

Dave.

 

[amirm]

OK, second speaker came out of the washing machine and here is the comparison:

So this is not sample variation. Nor was the EQ an issue (I had set it to flat). Levels did change on a hardware reset of the sample 2 so I quickly adjusted it and wound up being good bit lower than the first sample. So some variation due to that.

Until we get the same sample measured in an anechoic chamber, we will not be able to resolve the discrepency.

 

[amirm]

Didn't you figure out some padding stuff for that? I remember reading something to that effect.

All the recent measurements are with padding. It reduces the ripple by a factor of two but doesn't eliminate it. Over time I will work on better absorption.

 

[Hifihedgehog]

Barefoot Audio Footprint 01. Someone, anyone. I beg you to send one to Amir if you are lucky enough to own them. Since 2017, these seem to be FOTM every month on GearTrampz and they are the top seller at the audio pro’s go-to Vintage King Audio, whose HQ in metro Detroit is just 30 minutes away from my place. Who knows? Amir might be able to see if Barefoot might send him a loaner. Thomas Barefoot’s HQ is in Seattle, which is isn’t far from Amir if I am not mistaken and I am just dying to see if Footprint lives up to the hype or if it is just that: hype.

 

[Ron Texas]

The notch is too narrow to be of concern.

Preference ratings are just a number. There's lots of other things happening.

 

[napilopez]

OK, second speaker came out of the washing machine and here is the comparison:

View attachment 53544

So this is not sample variation. Nor was the EQ an issue (I had set it to flat). Levels did change on a hardware reset of the sample 2 so I quickly adjusted it and wound up being good bit lower than the first sample. So some variation due to that.

Until we get the same sample measured in an anechoic chamber, we will not be able to resolve the discrepency.

Thanks! Hmm. The mystery continues then. Strange that the bump is not in the S&R measurement - not a region you'd expect a discrepancy with an anechoic measurement.

Otherwise though the responses are very similar. The HF ripples in both of your measurements even line up, so your modifications to the mic cage seem to be working quite well there!

S&R sloppily overlayed and matched for aspect ratio in purple:

 

[TimVG]

All the recent measurements are with padding. It reduces the ripple by a factor of two but doesn't eliminate it. Over time I will work on better absorption.

Wouldn't an adjustment of the mic calibration file be an option? Less hassle.

 

[hyperplanar]

Wouldn't an adjustment of the mic calibration file be an option? Less hassle.

I don't think that would work. There certainly seems to be a general trend in the measurements so far, but I would expect the ripples to be a bit different depending on the design of each measured speaker.

 

[QMuse]

To some extent yes. At the high frequencies though, there is a bit of comb filtering in my rig which I can get rid of by eliminating the mic protection cage. But I prefer to not chance it.

Maybe you can ditch the protection cage just once to see what the difference would be?

 

[hyperplanar]

Maybe you can ditch the protection cage just once to see what the difference would be?

Take a look at the 8341A measurements, they were done without the cage.

 

[amirm]

Maybe you can ditch the protection cage just once to see what the difference would be?

I did that with the Genelec. That's how I know what difference it makes.

 

[amirm]

Wouldn't an adjustment of the mic calibration file be an option? Less hassle.

The issue is that sound reflects back and forth between the microphone fixture and face of the speaker, causing cancellation and boosts. You can't EQ that because it is dependent on the design of the speaker, location and angle of the microphone, etc. I think we just need to learn to ignore it.

 

[TimVG]

The issue is that sound reflects back and forth between the microphone fixture and face of the speaker, causing cancellation and boosts. You can't EQ that because it is dependent on the design of the speaker, location and angle of the microphone, etc. I think we just need to learn to ignore it.

Agreed, it's trivial compared to potential damage to the rig, and to what the rest of the spinorama reveals. A simple disclaimer would be sufficient imho.

 

[ctrl]

The issue is that sound reflects back and forth between the microphone fixture and face of the speaker, causing cancellation and boosts. You can't EQ that because it is dependent on the design of the speaker, location and angle of the microphone, etc. I think we just need to learn to ignore it.

Can you publish some pictures of the protection cage on the microphone (or have you already done so)?

Maybe a forum member can think of a solution how to further minimize or avoid the problem with reflections.

The notch is too narrow to be of concern.

You should distinguish between "normal" and professional use. For professional use the speaker is out of question at all. Nobody would buy an instrument where the F#5 would only play almost half as loud as all other tones.

The decay problem at 750Hz that Amir showed in the CSD diagram is not even considered.

We don't even know if the error can be completely eliminated by closing the bass reflex port.

The bump between 800 and 1700Hz on the other hand, is relatively unproblematic and can easily be eliminated by a suitable filter.

 

[BDWoody]

I suspect this is a termination issue when chaining multiple (greater than two) speakers.

The JBL 70XP speakers don't properly configure a termination scheme where the last speaker (and only that speaker) has the proper 110 ohm AES terminator.
Each speaker has its own 110 ohm terminator and if you continue adding speakers via the feed-through jacks, the parallel combination continues to further load the source. This seems to work okay for two speakers, but when you start adding third/fourth/etc, you will run into a problem.
I fail to understand how they messed this one up.

The proper way to do it would be as the Dutch & Dutch folks have. You have a portable 110 ohm XLR connector that plugs to the feed-through jack on the final speaker. Since the speakers themselves do not have a termination internal this scheme works correctly.

This is not unlike an old 10-base-2 ethernet system or the CAN Bus in your car. Chaining multiple devices works well as long as you terminate at the last device and don't have any "stubs" along the way that can cause reflections.

Dave.

Thank you for that...been trying to sort out some aes issues...let me get that plug...

Cheers.

 

[TimVG]

Nobody would buy an instrument where the F#5 would only play almost half as loud as all other tones.

Except that sounds are made up of fundamentals and overtones, the dip represents only a small part of the sound. Having owned the 705i and checked for myself, it is of little consequence in a real world environment. YMMV.

 

[ctrl]

Except that sounds are made up of fundamentals and overtones, the dip represents only a small part of the sound. Having owned the 705i and checked for myself, it is of little consequence in a real world environment. YMMV.

With an audio tool for professional use, such an error should simply not occur.

With a little better damping (or internal Helmholz resonator) the notch could have been significantly reduced (for 1-2dB less maximum level in low bass).

If the bass reflex port had been moved from the front to the rear, the resonance at 750Hz might have been in phase instead of phase opposition and less pronounced.
In this case the resulting hump could have been reduced by means of a filter (the disadvantage is that wall mounting would no longer have been possible).