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"This Harbeth User Group (HUG) is the Manufacturer's own managed forum dedicated to natural sound from microphone to ear, achievable by recognising and controlling the numerous confounding variables that exist along the audio chain. The Harbeth designer's objective is to make loudspeakers that contribute little of themselves to the music passing through them.

Identifying system components for their sonic neutrality should logically proceed from the interpretation and analysis of their technical, objective performance. Deviations from a flat frequency response at any point along the signal chain from microphone to ear is likely to give an audible sonic personality to the system at your ear; this includes the significant contribution of the listening room itself. To accurately reproduce the recorded sound as Harbeth speakers are designed to do, you would be best advised to select system components (sources, electronics, cables and so on) that do not color the sound before it reaches the speakers.

For example, the design of and interaction between the hifi amplifier and its speaker load can and will alter the sound balance of what you hear. This may or may not be what you wish to achieve, but any deviation from a flat response is a step away from a truly neutral system. HUG has extensively discussed amplifiers and the methods for seeking the most objectively neutral among a plethora of product choices.

HUG specialises in making complex technical matters simple to understand, getting at the repeatable facts in a post-truth environment where objectivity is increasingly ridiculed. With our heritage of natural sound and pragmatic design, HUG is not the best place to discuss non-Harbeth audio components selected, knowingly or not, to introduce a significantly personalised system sound. For that you should do your own research and above all, make the effort to visit an Authorised Dealer and listen to your music at your loudness on your loudspeakers through the various offerings there. There is really no on-line substitute for time invested in a dealer's showroom because 'tuning' your system to taste is such a highly personal matter. Our overall objective here is to empower readers to make the factually best procurement decisions in the interests of lifelike music at home.

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If some of the science behind faithfully reproducing the sound intended by the composer, score, conductor and musicians over Harbeth speakers is your thing, this forum has been helping with that since 2006. If you just want to share your opinions and photos with others then the unrelated Harbeth Speakers Facebook page http://bit.ly/2FEgoAy may be for you. Either way, welcome to the world of Harbeth!"


Feb. 2018
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Harbeth C7 and my room treatment journey

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  • #16
    Originally posted by willem View Post
    Correcting a system electronically with only a computer as a source does not require a big investment: all you need is the affordable UMIK-1 calibrated microphone, plus free REW measurement software and the free Equalizer APO software to apply the REW correction curve (preferably with the Peace interface). If you use additional sources other than a computer you will need a hardware equalizer unit like the mini-DSP instead of the computer and Equalizer APO. If you want to go fancy and convenient, there are e.g. the various DSpeaker Antimode units, ranging from the cheap but excellent Antimode 8033 to tame subwoofers, to the all singing and dancing DSpeaker X4 that integrates this into a DAC and pre amplifier.

    These dsp room eq systems normally do not boost levels in a null/dip, or not much, because that would indeed require massive and potentially destructive power, and still not achieve much (the sound would disappear into the same black hole). So unless you deliberately set out to do so, there is not really any risk.
    Thank you for the advice. Willem. Very interesting indeed!

    Just out of curiosity:
    From what you write above I infer that you can use the REW software and Equalizer APO on a computer that you then use to play music into a DAC using the USB port. And that the equalizer applies a
    correction profile on the USB device into the PC. Is that correct?

    And can you tell us more about how equipment like the antimode units can be integrated into a conventional hifi system without subwoofers? Will the antimode unit (like the Anti-Mode 2.0 Dual Core) integrate between the source (like a streamer) and the amplifier?

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    • #17
      1 Almost correct. The sequence is: computer with correction curve created by the REW software and applied to the Equalizer Apo software. Digital output via usb into the usb DAC (in my case an ODAC). The analogue output of the DAC then goes into an amplifier, or in my case an Emotiva Control Freak volume control plus Quad 405-2 power amplifier (I don't need a pre amplifier since the computer is my only audio source).
      2 There are various models of Antimodes. In my main system I use the 8033 to tame the subwoofer (the 8033 can only equalize subs). For main speakers there is their Dual Core. It can serve as a basic pre amplifier/DAC using just a power amplifier. If you need more inputs you will also need a pre amplifier (or integrated). In that case, see here for connection examples http://www.dspeaker.com/en/technolog...examples.shtml

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      • #18
        And here is then part three of my room treatment journey

        In the first two parts I had established an approach to treating my room (part 1) and then fed back the results and learnings for all to benefit from.

        But before I continue I want to thank coltma and willem. They gave me the advice to start measuring things. I followed their advice and things turned out for the better. Thank you guys!!

        So what happened?
        I was given a laptop and bought a MiniDSP Umik-1 measuring microphone. I installed the RoomEq Wizard software (REW), calibrated the set and started measuring things. A picture says a thousand words is the saying. So I post a frequency response graph below.
        The before situation (green line) clearly shows the room mode peaks from 70-150 Hz. It occured that the peak was actually around 20 dB! The red situation, though far from ideal, does not have the room mode peaks at this frequency. The difference was obtained by just positioning the speakers and listening chair differently. I experimented a lot and have around 60 measurements now.
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        Another things that became clear by measuring is that the decay times below 250 Hz are far to high. They indeed cause the ringing effect that can still be heard (though less annoying then before). See the second graph that shows the waterfall picture of the red measurement. I also posted the Topt graph. This graph is clearly showing that decay times in the low end (<500Hz) are too high. From literature it can be obtained that the decay time <500Hz should be around 700 ms for critical listening where the decay time >500 Hz should be around 500 ms.
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        Conclusions:

        1) If you have audible problems in your room you have to measure to see what is going wrong. Today this is not expensive anymore: the Umik-1 microphone is 75 USD and the REW software is free.
        2) You can achieve a great deal by positioning the speakers/listening position carefully. I am in the lucky circumstances that I can do this unlimited as I have a dedicated listening room.
        3) Positioning results with measurements lead, in my case, to an unexpected result: the Harbeths are very close to the front wall (60 from baffle to wall). This is, so far, the best position in my room as measured. This goes against any generic advice but, as I learned, is not at all special if you start to use measurements to optimize the speaker positions.
        4) Positioning alone cannot solve everything. Long decay times are not solvable by positioning and flattening the frequency response is not always possible as well. So, in my case, more is needed!

        Next steps:
        My system sounds much better now! Cleaner and with much less bass ringing... But still not as good as it can be. So more is needed. I will start working the next steps:
        1) Spend some additional time finetuning the speaker positioning to see if I can flatten the response further.
        2) Once I found the best possible speaker position, I will start using roomeq (plug in into foobar2000) to see if an REW compensation file can help to improve things.
        3) In parallel I will investigate what I need to do to reduce the decay time to 700 ms < 500 Hz. I assume it will need a lot of basstrapping....

        So, to be continued, my friends!





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        • #19
          Part four (it is getting lengthy ):

          Another month of experimenting and learning has gone by. What did I find out?

          First:
          Tweaking the speaker positions did not yield any significant result anymore. So the speakers are optimized where they are (for now at least).

          Secondly:
          I used the roomeq plugin in foobar2000 for a few weeks to try DSP in my system.
          The roomeq plugin is really nice! You can measure a frequency response graph using the measurement microphone and then tweak the eq settings. After some back and forth I configured the graph to be straight from 30 Hz to 18 kHz. And I listened for a few weeks....

          The first thing that became obvious is that the room mode @ 70Hz was less audible. It was not as irritating anymore as without DSP. It was also immediately apparent that the high end was sparkling more. The mid range (voices) were improved as well. All these effects could clearly be derived form the frequency response improvements that the DSP enabled.
          After a while it surfaced that there was a lack of low end bass and that the highs were a bit irritatingly sparkling. I also noticed that the music was more compressed and much less dynamic then before. So eventually I decided that the cons of the DSP were stronger than the pros. I switched the DSP off again.

          The third thing I learned was that I indeed need a LOT of basstrapping. I asked www.gikacoustics.co.uk for advice. And they said (and I quote) "This room is admittedly one of the worst I have seen this year". I am discussing the next steps with them...

          To be continued...

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          • #20
            I am a bit surprised by your dsp results.
            1 I would avoid equalizing much above the Schroeder frequency of the room. If the room is too bright, damping material will be the preferred way forward.
            2 A somewhat thin bass after room equalization is not surprising. After all, by eliminating peaks you are turning down the bass. So it is quite common to turn up the bas slightly after room eq.
            3 I have no idea why the sound should be less dynamic. Did you measure dynamic range? It may be that the music sounds less dynamic because it is so much cleaner.

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            • #21
              Willem wrote in#11: all you need is the affordable UMIK-1 calibrated microphone, plus free REW measurement software and the free Equalizer APO software to apply the REW correction curve (preferably with the Peace interface). If you use additional sources other than a computer you will need a hardware equalizer unit like the mini-DSP instead of the computer and Equalizer APO.
              Assuming that all actions have been carried out correctly, can you expect an equivalent result when applying a mini-DSP instead of the computer and Equalizer APO?

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              • #22
                Yes that should be the same.

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                • #23
                  Originally posted by willem View Post
                  I am a bit surprised by your dsp results.
                  3 I have no idea why the sound should be less dynamic. Did you measure dynamic range? It may be that the music sounds less dynamic because it is so much cleaner.
                  I was surprised too, Willem.

                  As for your comment:
                  I did not measure dynamic range but I have a datapoint that suggests the cause of the dynamic range limitation.

                  With DSP I had to correct quite a bit to get the bass flat. The result was that I had to turn my volume knob from ~9 o' clock to ~11:30 for the same volume. This is an indicator for a lower input voltage where the power amplifier has to compensate for. This eats into the dynamic headroom of the power amp. So I think that, because of this, the power amp ran out of steam at loud passages therewith limiting the dynamic range.

                  Please note that I used software EQ plugged into a software audio player. The advantage of a hardware DSP can be that the manufacturer of the DSP device can add a voltage gain stage after the DSP chip to compensate for the lower output.

                  What do you think?

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                  • #24
                    @ Willem. REW is very complicated. You wrote in another thread that you had found some assistance on the web. Would you be so kind and share some links?

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                    • #25
                      https://www.youtube.com/watch?v=e4uSR3cUUSY
                      https://www.youtube.com/watch?v=1NPOQw04NtQ
                      https://www.roomeqwizard.com/help/he...ngstarted.html
                      https://www.minidsp.com/applications...setup-with-rew
                      https://www.audiosciencereview.com/f...mies-part-1.4/
                      There is plenty more, and I am afraid I do not remember what I used myself at the time.
                      Good luck.

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                      • #26
                        Originally posted by Frisian View Post
                        @ Willem. REW is very complicated. You wrote in another thread that you had found some assistance on the web. Would you be so kind and share some links?
                        There is also a very good help function that explains all the functionality very well! But, you can only draw conclusions from many of the applications output if you know what it tells you. ANd for that you need to learn about acoustics. The REW manual/help will not help there.

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                        • #27
                          @Wilem. There are a few links that I did not know yet. So I can continue.Thanks!

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