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Historical - Harbeths and room correction - output to below 31.5Hz

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  • Historical - Harbeths and room correction - output to below 31.5Hz

    I've just bought a pair of 7ES2s for my second system,which is in a small back bedroom measuring 3.0 x 2.5 metres. They have replaced Omega Super 6 XRSs, so quite a change!

    My main difficulty with this system is over-exciting the room. I play music at about 70 to 75dB average SPLs. So I use room correction in the form of a Lyngdorf RP-1. Once set up, this provides correction in both the frequency and time domains.

    I've achieved great results with the Harbeths, with additional measurements showing a fairly flat response. I get a decent output at 40Hz, something at 31.5Hz and even some burbling at 25Hz!

    I'd be interested to know the experiences of anyone else using digital room correction.

    PS: the amps I am using are an Audion Sterling Anniversary EL34 and an Ampino.

  • #2
    Positive correction and boosting - caution

    Originally posted by bronal View Post
    I've just bought a pair of 7ES2s for my second system,which is in a small back bedroom measuring 3.0 x 2.5 metres. They have replaced Omega Super 6 XRSs, so quite a change!

    My main difficulty with this system is over-exciting the room. I play music at about 70 to 75dB average SPLs. So I use room correction in the form of a Lyngdorf RP-1. Once set up, this provides correction in both the frequency and time domains....
    Interesting. Do be careful though that your room correction system is not applying massive boost at any frequency, especially the very deepest frequencies. You need to keep an eye on how much positive (boost) correction is applied because all drive units - and an 8" drive unit is not that big compared with what you'd find in a cinema - has a limit on how much forwards and backwards excursion it can handle (obviously).

    Negative correction (cut) is not an issue though as it results in the drive unit working less hard.
    Alan A. Shaw
    Designer, owner
    Harbeth Audio UK

    Comment


    • #3
      Using with care

      Originally posted by A.S. View Post
      Interesting. Do be careful though that your room correction system is not applying massive boost at any frequency, especially the very deepest frequencies. You need to keep an eye on how much positive (boost) correction is applied because all drive units - and an 8" drive unit is not that big compared with what you'd find in a cinema - has a limit on how much forwards and backwards excursion it can handle (obviously).

      Negative correction (cut) is not an issue though as it results in the drive unit working less hard.
      I'm using the 'open' voicing curve, which is -2dB down from about 80Hz.

      Comment


      • #4
        Flat

        What I also meant to say was that 'flat response' refers to the operating range of the 7ES2s.

        Comment


        • #5
          Flat response using an overall average measurement

          Originally posted by bronal View Post
          What I also meant to say was that 'flat response' refers to the operating range of the 7ES2s.
          The frequency response of the room can contain deep notches even if the frequency response of the speaker is flat. Attempts to compensate for the notches may result in too large excursions of the speaker diaphragm. Such large excursions may produce increased distortion of the sound.

          I don't boost any frequencies when I use my room correction system. Instead, I cut out resonances of my room by means of MathAudio Auto EQ. The location of both notches and resonances depends on the location of the measurement microphone (I use Behringer ECM8000). I make no less than 5 measurements around my chair. Then I use the average frequency response for correction of my room. The average frequency response is much flatter than a “single-point” frequency response and produces much better sound when I use it for the room correction.

          I am also interested to know the experiences of anyone who uses digital room correction.

          Comment


          • #6
            Antimode room-sound equalization (caution about subwoofers in normal rooms)

            Some time ago I decided I wanted to reproduce the lower frequencies that can be found on good digital recordings. I installed a subwoofer known for its tight and controlled bass. However, even in my (very) large listening room and using the Quad 33/303 amplifyer with its sub-bass cut, the bass sounded woolly and lumpy. I was obviously suffering from room modes that only went away if I reduced the volume of the subwoofer to levels where I almost might just as well not have bothered with one.

            I then bought a DSpeaker Antimode 8033, and all of a sudden the sub integrated perfectly with the main speakers for a clean smooth and tight bass. The difference was remarkable. Installation was simple (it decides automatically for you what equalization is required, and does not try to boost dips). So my conclusion is that in many situations a sub without room correction is a bad idea.

            This, of course concerns the very lowest frequencies as reproduced by my sub. There is now also an Antimode for full range speakers, but I am not sure how well the idea works at the higher frequencies that probably need to be controlled in much smaller rooms.

            Willem

            Comment


            • #7
              Clean LF thanks to DSP

              I purchased a DSpeaker Antimode room correction device for my 40.1's. I have a rather odd shaped large room and sit about 20 ft from the speakers. Also I Have a Velodyne sub. I found the the room correction device made a significant difference by cutting down the multiple room resonances. The DS does not boost nulls but it does clip off peaks and makes music just sound more natural. Yes it's expensive(about $1200) but the improvement is worth it. I have reasonably clean output to about 30Hz.

              Comment


              • #8
                Room eq at low frequencies

                I am glad you also had good results, even with a Velodyne sub that presumably has its own more limited room equalization. The Antimode Dual Core 2.0 for full range speakers is indeed much more expensive that the 8033 for subwoofers. You also get a pre-amp and Dac with it, however.

                From what I understand, room equalization works best at lower frequencies.
                Willem

                Comment


                • #9
                  Electronic or physical damping?

                  I am planning on buying this unit too for my SHL5 as they are set up in rather a smallish space. However, I have the room treated with absorption and diffusion panels quite well and wonder if it would make much of a difference.

                  Comment


                  • #10
                    Zsystems preamp

                    In my approximately 20' x 15' x 8' room I use a Z-systems rdp-1 digital pre-amp to make some basic frequency response adjustments. Mainly what I do is to reduce a bump at 80 Hz, and then bring the treble down 3 dbs from 3150 Hz up.

                    I tweak some of the other bass frequencies slightly - nothing drastic. (It's not that the M40s have too much treble, but that most recordings do - being recorded too close - to my ears). I do listen near-field, the M40s being 6 1/2 feet apart and my listening position being 4' from the plane of the speakers.

                    Comment


                    • #11
                      Free Room EQ plug-in

                      At this moment I use a free Room EQ plug-in for Foobar2000: http://www.hydrogenaudio.org/forums/...owtopic=103603
                      IMHO, Foobar2000 is the best free audio player for PC.

                      Comment


                      • #12
                        How does it work?

                        Originally posted by pronto View Post
                        At this moment I use a free Room EQ plug-in for Foobar2000: http://www.hydrogenaudio.org/forums/...owtopic=103603
                        IMHO, Foobar2000 is the best free audio player for PC.
                        This looks very interesting, but room EQ software is unfamiliar to me. Does it work by taking a measurement at the listening position across the audible frequency range and then when playing back puts the opposite EQ on the signal to cancel the room effect out?

                        Can you take a measurement for more than one listening position?

                        Does it negate the need for *any* room treatment?

                        Will any non-linear FR of the speaker also be cancelled out?

                        Jeff

                        Comment


                        • #13
                          Practical outcome of room correction

                          Originally posted by pronto View Post
                          I am also interested to know the experiences of anyone who uses digital room correction.
                          See below.
                          Originally posted by aklac View Post
                          I purchased a DSpeaker Antimode room correction device for my 40.1's. I have a rather odd shaped large room and sit about 20 ft from the speakers. Also I Have a Velodyne sub. I found the the room correction device made a significant difference by cutting down the multiple room resonances. The DS does not boost nulls but it does clip off peaks and makes music just sound more natural. Yes it's expensive(about $1200) but the improvement is worth it. I have reasonably clean output to about 30Hz.
                          I tested the same device, with my C7s, no sub. To me the improvement was not worth it, by a long way. See below. My guess is that a lot of your value came because of the sub in the system.

                          Originally posted by willem View Post
                          The Antimode Dual Core 2.0 for full range speakers is indeed much more expensive that the 8033 for subwoofers. You also get a pre-amp and Dac with it, however.
                          Since I already have a Marantz SACDP and a Quad 99 preamp, these features do not add value to me.
                          I did an extended test of the Dual Core yesterday, to see if it can confer better sound that I can obtain using the Quad 99 tilt controls and bass cut option. I will try to upload the before/after freq response charts that the unit displays after a 20 minute calibration process.

                          The reason I tested this unit was because I have recently moved the speakers to a less than ideal location, close to the walls and corners. At the end of the test the most important finding to me was how good the speakers are, even when working in less than ideal locations. And how good the Quad tone controls are to deal with this, in many cases coming very close to Dual Core and in others leaving only subtle differences, given the kind of music I like and the sound levels I play it at.

                          In short, I don't play music with driving, aggressive bass lines at moderate to high sound levels. Mostly acoustic jazz and vocals, Indian classical, Western classical piano, at moderate to low volumes, sometimes late at night where critical listening can raise its head. Most other times, music is the background to all that things that are happening at home.

                          My assessment on where (room correction) may make sense:

                          1. Speakers that go significantly lower than the C7s do. I don't use a sub.
                          2. Music with strong driving bass lines, that are usually the most affected by room acoustics and speaker placement, in a room that may be trickier than mine.
                          3. High to moderate sound levels - for my sound levels I did not find that the unit did the trick I like of low sound levels without losing bass presence. The tone controls do this just as well, and maybe better.
                          Even so, the price demands an extended at home audition, I suggest.
                          For me, the differences were too subtle for the music I like to justify even USD 300, let along the USD 1100 for the unit.
                          To quite an extent this means kudos to the C7s too. Real world speakers, for sure.

                          Also, room eq can never make speakers sound better in absolute terms. All it can do is reduce the sound degradation cause by room resonance, and once this is done, the constraint moves back to the speaker side. It is therefore worth considering that once these resonances are removed, will you like what is left behind? Sometimes, the opposite can be true, based on tastes and inherent speaker quality.

                          From the photos, the red graph is the room response, before correction. Does anyone have any insights as to what it may be saying about my room from a sound quality perspective?

                          There are two graphs because I did it twice to make sure that calibration quality wasn't causing the result I was getting. While there are differences in the two, they appear small, and certainly did not result in anything different in the AB testing. By the way, the unit makes this testing very easy to do - there is a bypass button on the remote, toggle that to go back and forth between corrected and uncorrected sound.
                          Attached Files

                          Comment


                          • #14
                            Prompt feedback from DSpeaker designer in Finland and a question

                            To their credit, the company is very responsive. Last week, I received prompt replies to some questions I had.

                            After the decision to not buy, I wrote to them this morning with feedback, which was the least I could do, I thought.

                            I received a reply in an hour as follows, from the unit design team leader. Quote:

                            The default range for calibration is 140-190Hz, which doesn't much
                            affect much in the midrange. If correction up to midrange and above is
                            required, the unit needs to be calibrated using "Advanced" calibration
                            and then setting the frequency limit manually to around 400-500Hz. This
                            particularly improves vocals and certain instruments.
                            Unquote

                            Midrange quality is very important to me for vocals and instrumentals. I have been very happy with the C7s, for the way they deliver these sounds. I am in two minds whether I should expend the effort in trying out what is said above, but I suspect that this will result in another of those subtle differences. Any suggestions or experiences in the areas he is talking about, using Harbeth speakers?

                            I haven't found much difference in the midrange from when they were in free space to where they are now. So the room effect overall isn't an issue. Would moving the speakers closer to the walls have had a big midrange impact? And if I were to attempt correction for these impacts via the preamp tone controls, what should I be doing?
                            Advanced calibration is going to need skill too, if it is to have the claimed improvement effects.

                            Comment


                            • #15
                              Remember Lyngdorf DSP?

                              Originally posted by Kumar Kane View Post
                              To their credit, the company is very responsive. Last week, I received prompt replies to some questions I had.

                              After the decision to not buy, I wrote to them this morning with feedback, which was the least I could do, I thought.

                              I received a reply in an hour as follows, from the unit design team leader. Quote:

                              The default range for calibration is 140-190Hz, which doesn't much
                              affect much in the midrange. If correction up to midrange and above is
                              required, the unit needs to be calibrated using "Advanced" calibration
                              and then setting the frequency limit manually to around 400-500Hz. This
                              particularly improves vocals and certain instruments.
                              Unquote

                              Midrange quality is very important to me for vocals and instrumentals. I have been very happy with the C7s, for the way they deliver these sounds. I am in two minds whether I should expend the effort in trying out what is said above, but I suspect that this will result in another of those subtle differences. Any suggestions or experiences in the areas he is talking about, using Harbeth speakers?

                              I haven't found much difference in the midrange from when they were in free space to where they are now. So the room effect overall isn't an issue. Would moving the speakers closer to the walls have had a big midrange impact? And if I were to attempt correction for these impacts via the preamp tone controls, what should I be doing?
                              Advanced calibration is going to need skill too, if it is to have the claimed improvement effects.
                              Are you still using the Lyngdorf? If you are .... I would like to share this experience in room correction.

                              1) the room correction, you would most likely experience a stronger differences between, with the rp-1 or bypass the rp-1, right? Somehow, the "space" and "airiness" might have been compensated.

                              - the way around this, to correct the room more effectively and having the system to have the bypass and non bypass of rp1, to have the "same" space and airiness... the trick is on the mic placement. You can achieve a corrected freq to suit the room issues, and yet maintaining the space and airines and with a mid range control.... and yet a flat curve for the room too. (Room correction corrects the freq down for all troubled area of freq and there will be no boost in any freq)

                              2) 2 of the major spots, which are the point 2 & 3 generally, instead of the recommended face front, point them to the facing side walls, the centre (listener spot, will still be front facing and ears' level). As for mic facing walls, that also includes the other walls (rear side left/right). Depending on your % correction achieve, you can further add in more points, ie, rear side pointing up to corners... etc. A little tough for me to describe..... but I guess, you might get the idea.

                              With these points, what is been achieved is that it reads the room's layout much better... space and airiness maintained , final target is to get 95% and above, between bypass and non bypass, you should achieve least difference in space & airiness, and yet achieve the flat line in freq for the room. Do not be shy with more points recorded on the mic.... The key is side walls ;-)

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