No need to export measurements. Give me the REW file itself, which contains the measurements of these speakers. Just attach the REW file to the message, as I did for the example.
Okay.
We look at the RT60 graph, this is the signal decay time at -60 dB at each frequency. As you can see from the graphs, each speaker has a different signal decay time at different frequencies, this already shows us that these speakers cannot sound the same in these acoustic conditions. We don't pay attention to the black line.
Next, we look at the step response. These two speakers have very different step responses, I don't want to describe what depends on what, but I think it's worth mentioning that in order for the speakers to sound the same, they must have the same step response. Or very close to each other.
In all your measurements, the room itself greatly influences the measurement result, but if you measured different speakers in the same room, then in fact we see how the speakers behave together with the room, roughly speaking, we can see the character of the speakers, but we cannot say for sure what the character of the speakers themselves is, or the room makes them show some of their character traits.
In fact, judging by the step response, I strongly suspect that the measurements were made in different acoustic conditions.
We look at the RT60 graph, this is the signal decay time at -60 dB at each frequency. As you can see from the graphs, each speaker has a different signal decay time at different frequencies, this already shows us that these speakers cannot sound the same in these acoustic conditions. We don't pay attention to the black line.
Next, we look at the step response. These two speakers have very different step responses, I don't want to describe what depends on what, but I think it's worth mentioning that in order for the speakers to sound the same, they must have the same step response. Or very close to each other.
In all your measurements, the room itself greatly influences the measurement result, but if you measured different speakers in the same room, then in fact we see how the speakers behave together with the room, roughly speaking, we can see the character of the speakers, but we cannot say for sure what the character of the speakers themselves is, or the room makes them show some of their character traits.
In fact, judging by the step response, I strongly suspect that the measurements were made in different acoustic conditions.
The phase response is very different between these two speakers. These speakers are simply bound to sound different. And this is without taking into account their amplitude response.
Some good responses here, though I fear it's not easy.
The solution to the problem is to understand the normal acoustic issues and build a good speaker. If one focuses on issues that appear connected with 'fast' response they may miss the real issues. I sometimes suspect a discussion of how these are unrelated would be productive in cases like this since there seem to be two polarised schools of thought.
The solution to the problem is to understand the normal acoustic issues and build a good speaker. If one focuses on issues that appear connected with 'fast' response they may miss the real issues. I sometimes suspect a discussion of how these are unrelated would be productive in cases like this since there seem to be two polarised schools of thought.
Not paying attention to step response can also lead to real problems.
This is too universal a statement. What to do if a certain person initially likes a sound "colored" by resonance phenomena?
I suspect we're on the same page but since step response duplicates parameters discoverable elsewhere, I don't specifically use it.
It was meant to be, saying there's not a shortcut, and it alludes to the fact that it's the other parameters that make this come together so they can't be ignored.
In my opinion, first build a proper speaker, then mess with the response. There are issues that we all have in common and want to solve, that go beyond response. As it turns out, the more of these we fix, the less we may want a custom response 😉
I agree that step response duplicates some parameters, but it is sometimes very convenient, for example, for mixing acoustic centers in phase-linear multi-band speakers. It is also much easier to see how filters introduce a delay into the signal. In general, it is sometimes a very convenient thing for analyzing the achieved result.
At the same time, I have never said and do not say that step response is the only determining criterion for good sound. This is one of the criteria that shows at a glance whether everything is good or bad with the phase and amplitude of the signal.
It depends on the goal being pursued.
But in general, I agree with this statement.
If I disagree with you here, we would miss the point on all the things we agree about. You're not wrong, even if some people do it differently.
I know but other seems not to...
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Well, yes, but not for the reproduction of the decay of an instrument playing in a room. Thats far longer time aspects than the decay of an impulse. Completely different thing.
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Just a sidenote: In no way did these midwoofers have an fs of 400 Hz. In the measurement plot that you show it is clear that the fc is around 55 Hz. Back then when they were new I didn't like the sound of these speakers at all. Part of that was their lacking bass extension.
Regards
Charles
To be honest, this statement sounds very strange to me. Since the impulse response contains all aspects of the measured playback system.
The impulse response is like a "fingerprint" of the entire system: loudspeaker + room + microphone position.
It contains:
-the direct component (the speaker itself),
-reflected energy (room acoustics),
-reverberation (decaying tails).
But not everyone can read the impulse directly, since it contains a lot of information in an inconvenient form for its interpretation. For example, I can't read the impulse directly, but sometimes I look at the impulse response for the time of the first reflections from the walls. They are not so clearly visible on the step response.
Yes, as you say - is not so easy to see a FR deviation in a pulse response graph. And, your listening impression is based on a lot of reflections - maybe up to 90% if we are to believe Amar B. I stand by my statement that an anechoic impulse response and the listening impression of an instrument decay reproduction is two very different things.
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It is possible to state with certainty, based on the measurement results, that the impulse of the speaker system obtained in an anechoic chamber and the impulse of the same speaker system obtained in a living room are different impulses.
It is also possible to state that listening to the reverberation of musical instruments through the speaker system in an anechoic chamber and in a living room will be perceived by the ear differently.
But I would definitely not state that the impulse response does not reflect the speaker's ability to reproduce the reverberation of instruments.
It is strange, as the impulse response indeed is… and step response and impulse response are mathematically related.
I agree on all this. Just wanted to make sure that no reader mixed up the two different mechanisms mentioned as both was referred to as "decay" - one that take about 200uS and an other taking perhaps 1300ms. I mean, who answers "Did you check your impulse response" when someone asks why Saxophone sound muddy in my system... Usually the question is phrased - did you check the FR? Asking about the impulse response is a bit more involved and advanced compared to discussing FR I would say. One need to do the FFT and all...
That was all ;-)
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That was all ;-)
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Ihe measurement were taken in the very same room 😉 The differences may come from a radical way that Revox had chosen to impulse-align BX-350 drivers, that's a stepped baffle. I am doing in-room listening triangle measurements on purpose as they - just as you mentioned - show how do the speakers go on with room modes, reflections etc. I am aware how different these speakers sound and can easily express these differences by air as far as tonality, precision, scene or dynamic abilities are concerned, but these are all just perceived and sometimes quite abstract criteria. Reproducing reverberation/echo from the source material by the speaker drivers is a very instrument-dependent subject, as every instrument and every room, never mind a real room or virtually added by reverb plug-in into the mix, has its specific spectrum of reverberation that is the most obvious for the listener. That's why I started with something such simple as measuring SPL at different amp voltage at the speaker terminals. Some basic logic - which is misleading of course - told me that if such SPL vs. input voltage grapg would be steeper for one speaker than it would be less or more rev/echo capable than the other one. But w are still talking about an echo or reverberation that comes from a source signal. Speakers can add or subtract, room can attenuate or not, that's interesting in any way. BTW: Why your REW has an STEP button and mine does not? 🙂
Hi Charles,
whay You see is my listening rooms first mod at 52 Hz. Here is the impedance curve of these speakers taken by German testers in 1970's:
...and the resurrecting truth stamped on the speaker magnet 🙂 (photo taken by one of Revox enthusiasts: https://www.technikundnatur.eu/revox-lautsprecher/revox-bx-350.html)
...and yes, these speakers ar not a bass-reflex-like bass-boomers, but the quality of the bass is exceptional, as it is superfast. Huge magnets, superlight paper cones that go up to 3200 Hz. One of my favorite speakers of all times. For earth-shaking I have Revox Emporium B. Any bass-reflex speakers have a no-go to my room since a few years 😉
All the best,
Mike