"House sound" Do the designers here have a "house sound"?

[DDF]

Re: "House sound" Do the designers here have a "house sound"?

Move the speaker and mic away from the fence another 5 or 6 feet.

For sure. Rough rule of thumb, wall to mic distance > floor to mic distance. The set up shown will result in the window being limited by teh fence or if teh fence reflection is included in teh FFt window, bass/lower mid response being elevated relative to 4pi, plus a notch, which will be hard to account for.

The mic set up is a wand that screws in where the capsule goes, and then screw in the capsule to the wand. It adds about a foot. The gooseneck is used to get the extra reach needed to the ladder top.

Dave, if I characterize the effect of the ladder, I'll post it (always do). Averaging improves SNR by 3dB per every 2x averages, if noise is random.

Dave

[Jeff B.]

Re: "House sound" Do the designers here have a "house sound"?

For sure. Rough rule of thumb, wall to mic distance > floor to mic distance. The set up shown will result in the window being limited by teh fence or if teh fence reflection is included in teh FFt window, bass/lower mid response being elevated relative to 4pi, plus a notch, which will be hard to account for.

The mic set up is a wand that screws in where the capsule goes, and then screw in the capsule to the wand. It adds about a foot. The gooseneck is used to get the extra reach needed to the ladder top.

Dave, if I characterize the effect of the ladder, I'll post it (always do). Averaging improves SNR by 3dB per every 2x averages, if noise is random.

Dave

Just a sidebar, but several years ago I had an opportunity to tour a professional facility that had an anechoic chamber (today the facility is owned by Harman). Their mic was attached to a very solid steel structure that had the ability to make some very precise adjustments. I understood that part, but I commented on the sheer heft of the structure. They told me, and then showed me some measurement examples, that showed that a standard mic stand like we all pretty much use is subject to micro-oscillations from the device under test (the speaker) and these small movements show up in the frequency response. The plot with the standard mic stand had little tiny ripples in the response, while the one made using there massive mic stand was very smooth in comparison. They assured me no additional smoothing had been applied. I thought this was pretty interesting and thought it was worth bringing up. Of course, I still use a standard mic stand with a boom.

[3ll3d00d]

Re: "House sound" Do the designers here have a "house sound"?

(Apologies for the mildly off topic digression but i guess this is an example of the measurement problem being discussed)

Move the speaker and mic away from the fence another 5 or 6 feet.

For sure. Rough rule of thumb, wall to mic distance > floor to mic distance. The set up shown will result in the window being limited by teh fence or if teh fence reflection is included in teh FFt window, bass/lower mid response being elevated relative to 4pi, plus a notch, which will be hard to account for.

Thanks for the comments. I hadn't considered the impact of the fence at LF tbh as I was thinking in terms of specular reflections to get more resolution higher up. My problem is that moving away from the fence brings the house itself into play. Now you mention it though I had noticed a fattening of the bass as I made the window wider, possibly not the end of the world in this case as it is an on wall speaker anyway.

Clearly what I really need is a bigger garden.

[andy19191]

Re: "House sound" Do the designers here have a "house sound"?

The plot with the standard mic stand had little tiny ripples in the response, while the one made using there massive mic stand was very smooth in comparison.

How was the mic attached to the two types of stands?

[Jeff B.]

Re: "House sound" Do the designers here have a "house sound"?

How was the mic attached to the two types of stands?

The big one used clamps on the barrel as the mic sat in a fixture. On the standard one, I didn't see it tested, but I assumed a plastic holder of some type.

[andy19191]

Re: "House sound" Do the designers here have a "house sound"?

The big one used clamps on the barrel as the mic sat in a fixture. On the standard one, I didn't see it tested, but I assumed a plastic holder of some type.

My question was imprecise. Was the connection via the clamps rigid or was there some rubber or equivalent to decouple the motion of the stand and the microphone?

[Jeff B.]

Re: "House sound" Do the designers here have a "house sound"?

My question was imprecise. Was the connection via the clamps rigid or was there some rubber or equivalent to decouple the motion of the stand and the microphone?

I would assume there was some kind of rubber pad in the clamp, but I really don't remember that detail.

[Jeff B.]

Re: "House sound" Do the designers here have a "house sound"?

My question was imprecise. Was the connection via the clamps rigid or was there some rubber or equivalent to decouple the motion of the stand and the microphone?

I would assume there was some kind of rubber pad in the clamp, but I really don't remember that detail.

[dlr]

Re: "House sound" Do the designers here have a "house sound"?

Dave, if I characterize the effect of the ladder, I'll post it (always do). Averaging improves SNR by 3dB per every 2x averages, if noise is random.

Oops, yes, I meant to say 9db. I'll bet that you see a big improvement in outdoor measurements with averaging. In what part(s) of the spectrum do you see the biggest improvement?

dlr

[DDF]

Re: "House sound" Do the designers here have a "house sound"?

Oops, yes, I meant to say 9dB. I'll bet that you see a big improvement in outdoor measurements with averaging. In what part(s) of the spectrum do you see the biggest improvement?

dlr

The experiments were cut short by drizzle, so I didn't get the chance to investigate this directly unfortunately.

I chose 8 averages, as 16 averages made the risk too high that some impulsive noise (a neighbour, a bird) might contaminate the measure. That's what really set the limit on averaging time, and noise reduction. To help combat this, I set the MLS length as short as possible to reduce time/acquisition. The min MLS length can be determined by knowing the maximum window length of the FFT.

[dlr]

Re: "House sound" Do the designers here have a "house sound"?

They told me, and then showed me some measurement examples, that showed that a standard mic stand like we all pretty much use is subject to micro-oscillations from the device under test (the speaker) and these small movements show up in the frequency response.

Something I had never considered, that is interesting. My mic wand is inside of a PVC pipe with synthetic felt wrapped around it to support it in the pipe and to allow me to slide the want in/out for fine adjustments. Probably helps with any induced oscillations. There's no clamp of any kind on mine. The PVC is bolted down onto the camera tripod, but that should be isolated from the wand due to the synthetic felt, except possibly for very low frequencies.

dlr

[DDF]

Re: "House sound" Do the designers here have a "house sound"?

The team I worked in used to have a full size anechoic chamber similar to the NRC's or Harmons. I used to work daily in a smaller anechoic chamber good down to about 80Hz. For mic stands, we used very non resonant solid stainless "wands" with brass end fittings.

Happily, I've not been able to detect any impulses or ripples with my mic stand

[dlr]

Re: "House sound" Do the designers here have a "house sound"?

The min MLS length can be determined by knowing the maximum window length of the FFT.

I've played around with the MLS length in LAUD, but always left it at the high setting, even though I didn't see much in the way of differences when using typical short windowed FFTs. I may be able to shorten mine as well, though given that it's still only a few extra seconds during measurements in my basement, it doesn't bother me that it takes a bit longer.

Happily, I've not been able to detect any impulses or ripples with my mic stand.

I don't know how I could even determine that, since it should be present to one degree or another in every measurement. I can't think of a way one could even characterize the influence of a mic stand. There's nothing to use to normalize a response to filter out the stand influence. It's not constant, either, since the stand is excited by the driver, so that idea wouldn't work anyway.

dlr

[DDF]

Re: "House sound" Do the designers here have a "house sound"?

I've played around with the MLS length in LAUD, but always left it at the high setting, even though I didn't see much in the way of differences when using typical short windowed FFTs. I may be able to shorten mine as well, though given that it's still only a few extra seconds during measurements in my basement, it doesn't bother me that it takes a bit longer.



I don't know how I could even determine that, since it should be present to one degree or another in every measurement. I can't think of a way one could even characterize the influence of a mic stand. There's nothing to use to normalize a response to filter out the stand influence. It's not constant, either, since the stand is excited by the driver, so that idea wouldn't work anyway.

dlr

There's no reason to shorten the MLS length unless you want to shorten the acquisition time. Standard usually works fine. For ultra low frequency measures, the MLS length is usually increased from standard

You can determine if the mic stand is resonating by looking at the waterfall of different drivers and systems. If a resonance of any importance occurred, you'd see a hanging decay in the same frequency range for all measurements on all drivers (so long as the resonance is in the driver's bandwidth)