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Ascilab C8C Active Speaker Review
- Thread starter amirm
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OP
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You take an ultra low distortion speaker at its optimal level and you generate distortion and determine level of audibility.
It is no different than varying frequency response using EQ.
If you had done these two, you would have found that the EQ variations are readily audible whereas distortion is far, far harder for untrained listeners.
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It was emailed when the speaker shipped
dickiefunk
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How does these monitors compare to the Neumann KH150 in overall performance and sound?
Curvature
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Easily compare loudspeakers measurements
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It's a very broad question you're asking. Generally, the C8C are the better speaker in most aspects, particularly in radiation control below 800Hz.
Performance wise they are both stellar and reviewed my amirm - you must have found the data.
Biggest audible difference in favour of the C8C is, that C8C is full range; i.e. covers more than one additional octave down deep. You actually get usable frequency response with acceptable distortion at moderate levels, down to below 20 Hz in an average sized room! They are absolutely mid-field suitable at least up until levels of 90 dB SPL @ 1m, after which sub-bass distortion becomes the limiting factor (but then there's the BX8C extension...).
So at nearly double the price (depending on your local market), C8C will always be the preferred speaker. Additionally to what @Curvature wrote.
Things might not be as easy when KH 150 gets properly paired with subwoofer(s). Then the influence of individual room acoustics and SPL requirements might lean someone towards the C8C or the KH 150 + sub(s).
And Neumann is a company with very high reputation and experience.
Ascilab is a total newcomer. If it comes to a technical problem or transport damage that cannot fixed by firmware update, we will see how those problems will be solved.
On Amir's homepage all Ascilab products are sold out.
The seller in Europe has only the F6B in white and S6B (the price for that is ridiculous) in black in stock.
People in my country that spend that amount of money, want to go to a store and listen to the speakers. Or take a sample to their home to test it.
Ascilab is a total newcomer. If it comes to a technical problem or transport damage that cannot fixed by firmware update, we will see how those problems will be solved.
On Amir's homepage all Ascilab products are sold out.
The seller in Europe has only the F6B in white and S6B (the price for that is ridiculous) in black in stock.
People in my country that spend that amount of money, want to go to a store and listen to the speakers. Or take a sample to their home to test it.
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What I did were speaker or system comparisons. Each speaker/system with a complex set of distortions. Measured differences had to be high for people to notice or pay attention in a real-world test for product decisions. Over time I learned what's required to make a difference.
You described a controlled test for audibility of distortion that is out of scope for most companies. Your suggestion to generate distortion of various levels can easily be implemented with sine waves but not with music. Sine waves allow introduction of HD and IMD of various levels. Sine waves are probably also the most discriminating test signal for HD. Probably not for IMD, though. And some forms of IMD are more audible than HD. We had this discussion before.
As audibility of HD depends on the base frequency, the order of the harmonic, the combination of harmonics and the playback level, there is a huge variation of tests that would have to be conducted with a large number of participants to get meaningful data. And the result would be the distribution of audibility thresholds across participants.
From the results of these audibility tests, a multi-dimensional model of HD audibility could be built, that allows processing of measured HD such that a distance to certain audibility thresholds (e.g. peak of normal distribution or inaudibility for 90% of listeners etc.) can be determined. That would finally make HD measurements more relevant than they are today.
However, you can't get a preference rating with sine waves that is in any way valid for music playback. All you get is worst case audibility. So you can't be sure if people are actually bothered by HD or even if lower audibility is always preferred. But at least that's a start. And if we set the target of inaudible HD, we would now have a valid threshold.
Now instead of the audibility tests described above, we could also apply masking thresholds as known from research. There are masking threshold models that include dependency on frequency, harmonic order (distance between masker and masked signal) and signal level. For combination of several harmonics, upwards masking of lower harmonics would have to be taken into consideration (e.g. fundamental + HD2 has a higher masking threshold for HD3 than the fundamental alone). See below an examplary masking threshold comparison for two different models. As you see, thresholds vary considerably across masking models.
So multidimensional models of HD audibility are basically available in form of masking theshold models.
EDIT: While Listen talks a lot about masking, what they actually do does not take masking into consideration although their results very much look like they would. Actually they calculate THD out of signal components that did not occurr at the same time during measurement. So their method makes absolutely no sense to me. Nevertheless, their video explains masking quite well before they propose their calculation method. They do apply masking curves in spectral plots but as it seems not in (T)HD weighting.
In any case, results of studies as you proposed would not be that linear distortion is generally more audible than nonlinear distortion because obviously both have audibility thresholds. But the result may be that this statement holds true for the typical set of linear and nonlinear distortion of some kind of average quality loudspeaker, whatever this may be.
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Has anyone taken delivery of these speakers recently? The wait seems to be long.....
When reading their return policy, there seems to be an awful lot of things they can claim to avoid fulfilling their obligations. I hope all that is just written in case someone returns a product in really bad condition, and not something they will regularly use to their financial advantage against customers who just happen to be dissatisfied with the performance of the product.
I do wonder what it would cost me, as a private person, to send back a pair of loudspeakers to France from Sweden with sufficient delivery insurance?
When AsciLab has sorted out their current problem with the lack of product availability, I think they should open up the market to a larger dealer network.
Curvature
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Why is that (more expensive) combination better than the C8C? It's difficult to make direct max SPL comparisons, but the KH750s produce 90dB SPL at 3% THD, equivalent to roughly -30dB. The C8C, at 96dB output, produces -22dB or 8%. Assuming linear behaviour, reducing the playback level by 6dB to 90dB SPL nets you -28dB in distortion, nearly the same level of performance. In real terms, distortion tends to increase at a faster rate than level, so that number is conservative rather than optimistic.
And this is setting aside the cardioid behavior, which is a key difference to how the speakers will sound in-room.
Curvature
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You make a good effort at gathering and interpreting information but much of what you write is either misleading or incorrect.
HD and IMD for a given device are integral to a device's output. The difference between the input and output is the transfer function. If you know the transfer function, you know what nonlinearities will be produced for any signal, be it music or a contrived signal. So it's wrong to say that IMD is more audible than HD—in a real device, with real signals, they are both part of the signal along with other nonlinearities. These metrics are produced only when isolated using specific test signals. Their purpose is transfer function diagnosis, and they were developed because the transfer functions of speakers and other devices are not known in advance. The complete characterization of a transfer function happens only in highly limited circumstances (like MEMS microspeakers in cellphones produced in the millions).
In experimental settings, nonlinearities can be systematically varied to test thresholds of detection and preference. Any signal can be used. You cannot expect anything useful with untrained listeners, in uncontrolled, casual settings. Speaker distortion is so hard to hear that, barring obvious circumstances like trying to reproduce low bass with a too-small speaker, or trying to test max output, there is no reason to try listening for it.
Where THD is useful it is as a quick, simple test of known masking thresholds and performance relative to other devices. It really has no validity beyond lower=better and egregiously high=bad. Audibility depends not only on level, order, etc. but also the signal used. The actual thresholds are so dynamic and variable that applicability of any findings beyond the very general can't be done. It's why controlled listening tests are the standard.
Try this: https://www.klippel.de/listeningtest/
No still awaiting delivery of c8c & bx8c, just got communication from Audiophonics that it's pushed out to beginning july instead of mid june. Anyone else having an update on delivery ?
sqrl
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The Kh150 has better latency for tracking, too...But I seriously doubt most consumers will be using either speaker for that. So... LOL.Easily compare loudspeakers measurements
It's a very broad question you're asking. Generally, the C8C are the better speaker in most aspects, particularly in radiation control below 800Hz.
Curvature
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KH150: Analog Input: 2.6 ms; SPDIF Input: 2.1 ms See link. https://www.neumann.com/en-us/products/monitors/kh-150
C8C: Analog input latency is about 350 µs; digital input latency is about 1.8 ms. Using linear‑phase mode adds an additional 24 ms. See attached manual.
Neumann is better with latency for phase linear corrections with the MA-1, which adds no additional delay.
Thankfully you are here to correct me.
For the same HD, IMD can be very different. This invalidates the complete paragraph above. The reason is that some nonlinearities in loudspeakers are frequency-dependent in their effect on sound produced by the speaker. So they can cause HD at one frequency while not causing IMD when adding a second frequency if the second frequency is not affected by the nonlinearity. Besides that, HD and IMD are different kinds of distortion that oviously also sound different. And for parts of IMD components, there is no masking signal. This means audibility can be very different. Correlation with perception depends on details of IMD measurement. Incompetent IMD measurements are the cause for low correlation often found in research.
While nonlinearities can be varied, this doesn't result in a specific percentage of HD or IMD for any given signal. If you introduce a nonlinear transfer function to a signal, the level of distortion depends on the signal level. When you apply a random signal, the level of distortion varies with the signal and is unknown. When combining sine waves, it's easy to precisely generate specific levels of (T)HD and IMD.
While some are interested in just noticeable difference (JND in scientific publications) others are interested in differences that make an average consumer pay higher prices due to obvious increase in sound quality. You may be happy to pay big money for theoretical improvements based on measurements or improvemens that only expert listeners hear. Normal consumers are not. In that regard, my testing is certainly useful to me.
THD as a test of known masking thresholds? Don't know what this means. Comparison to other devices is pointless if audibility is unknown. Due to details of auditory masking, the concept of THD is screwed. HD orders require weighting based on masking threshold before they can be combined into a single value.
I don't think you understood what I wrote in the post you replied to. Large parts were about making (T)HD more useful than it is today including quite detailed description how to get there and my own comparison of masking threshold models. Obviously, controlled listening tests are no standard for product evaluation. Measurements are the standard and they still require improvement to better correlate with perception.
(T)HD weighting against audibility thresholds is merely one step. One of the reasons is that lower is not always better. That's why most phones generate distortion in signal processing algorithms for support of bass output (virtual bass). This means audibility and preference may not be the same. Main reason is that IMD is more audible and always sounds bad. Correct IMD testing must be introduced to show audible differences between loudspeakers.
Ahhh...I didn't know that. Thanks for the info!
OP
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Production was halted for a good amount of time (due to international conflict) and has just restarted. I am *hoping* that they are able to fulfill orders this month for delivery in July to dealers.
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