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'Freshmen' with Harbeth 40.1 (part II)

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  • #16
    No bass effect?

    Hi, Mazokist,
    I'm curious that lowest bass control wouldn't be changing anything. Is the attenuator (left of Volume) off? Should be a loudness thing. Is the tone control enganged (left of bass knob)?
    Regards,
    Peter

    Comment


    • #17
      Loudness

      Hi,

      there should be a "comp" (loudness, more bass) switch located left of the switch for engaging the bass and treble potentiometers. That should be off imo.

      Regards,
      Peter

      Comment


      • #18
        Less acoustic power?

        @ drdennis If we use fact, that my room has poor acoustic properties, as a standing point - I can make conclusion that with a smaller speakers I will put just a smaller amount of energy in the room. Same effect I can get if I listening music, with my H40.1, on smaller volume and drive less power?

        @Bensim09 I'm geld to hear that you solve room acoustic problem - that fact give me a hope that I'm able to do something,too Please, send me some link of that 'melamin foam' producers, to check what kind of product it is.

        Comment


        • #19
          Glass window

          Dear Mr. Show,

          Thank you for time that you spend trying to find out right idea how to solve my 'room acoustic issue'. I really appreciated it.

          Reading your last post I find out that 'acoustic situation' in my room is even worse, because until now, I do not 'calculate' nothing that is on other side of curtain. Truth is that on another side is glass windows (all the way in upper part) and again sloped wall, as you can see on attached photos.

          Regards
          Attached Files

          Comment


          • #20
            Tone controls

            Dear chirhonix,

            as you can see from attached photos: tone control is engaged ( & bass knob is in 'min' position). Also attenuator is in 'off' position as well as loudness 'knob' - and still without any significant result
            Attached Files

            Comment


            • #21
              Check tone controls

              Originally posted by Mazokist View Post
              Dear Mr. Show,

              Thank you for time that you spend trying to find out right idea how to solve my 'room acoustic issue'. I really appreciated it.

              Reading your last post I find out that 'acoustic situation' in my room is even worse, because until now, I do not 'calculate' nothing that is on other side of curtain. Truth is that on another side is glass windows (all the way in upper part) and again sloped wall, as you can see on attached photos.

              Regards
              OK, I'll do what I can. About the amplifier and its tone control. Can you check the operation of the tone controls please? Please play some normal classical orchestral music. Whilst the music is playing press-in the Tone button and rotate the treble and then the bass control up and down. Can you definitely hear a change in sound when both controls are rotated up/down?

              Incidentally, I note from this evening's national commercial ITV, that award-winning The Cube (also here) was broadcast. It's made on Monitor 40.1s. We intend to run an article on the construction and use of the brand new ITV Leeds Emmerdale studios, which is made with the M40.1s. You can see one of the control rooms under construction. The big difference between these environments and yours is that they, like all serious professional studios, are acoustically treated to make then a relatively dry acoustic, free from echoes and with a controlled absorption at low frequencies. No great acoustics theoretical skill or fancy test equipment is required to construct such a room, although both make success more likely. What is needed is to make as high a proportion of the total surface area of the room absorptive. That means, in simple language, cover as much surface as possible with Rockwool - see picture. Can you see the white and black tea mugs in the middle of the picture on the battening? That indicates that the Rockwool is about 80mm thick.

              I fully appreciate that your listening room is not (and cannot and should not) be damped to professional standards, but to get the best of a professional speaker some attention will have to be paid to absorption. Believe me, in the cost-conscious world of TV, if studios and control rooms could be built without expensive sound treatment, they would be, but the creative staff usually win the argument over the accountants that for professional monitoring, it is really essential to separate the sonic character of the replay room from the recording itself.

              >
              Attached Files
              Alan A. Shaw
              Designer, owner
              Harbeth Audio UK

              Comment


              • #22
                I'll take a freadom and suggest conclusion of this thread

                Dear Mr. Show,

                I will follow your instruction and be focused on acoustic treatment of my listening/living room. At this moment I'm not able to do nothing in 'wall structure' but I will make research upon this topic and find out what is best solution for 'on wall treatment' . Also, I will try to make some 'acoustic vs. design' compromise and hope to get sufficient result on both field. As I rough direction can I follow some solution from attachment:

                regards and thank you again
                Attached Files

                Comment


                • #23
                  Wrong solution!

                  VERY IMPORTANT POINT!!

                  The four pictures you provided are NOT sound absorbers. (Actually the first one, the square with the slots cut in its face may absorb to a small degree).

                  You have shown pictures of sound scattering devices. Scattering sound does not absorb it. It just reflects it. Your problem may be inadequate absorption at low frequencies. These scattering devices will not help you at all. They will be invisible to high energy, low frequency sounds. Don't waste your time and money - they are designed to help with high frequency sound problems.

                  Remember what I carefully explained a few posts ago: if you are to absorb low/mid frequency sound you have to convert it to heat inside a fibrous material, like Rockwool or possibly Melamine. There is NO other solution. If these alternative products you suggest worked at low frequencies, professional studios would not use expensive Rockwool lines walls and ceilings. Like them you must use soft, thick, semi-rigid material.

                  What you show are hard, rigid, highly reflective surfaces - totally useless for low frequencies. I repeat: they are completely the wrong products.

                  P.S. I guess that your problems are below 100Hz in frequency. As you can see from this chart even 100mm thick malamine has almost zero absorption below 100Hz. Its excellent absorption properties are at 90% + for the middle and high frequencies, say from 300Hz upwards. So, even if you completely filled your room from top to bottom, side to side with melamine, it would barely effect the low frequencies. You are back to Rockwool again as the only viable surface treatment solution.

                  Proof:

                  Look at this page here describing the absorption of Rockwool. Look down the left column of the first table until you find '703, plain' 4" (102mm). Now look right until you see the number in the column headed 125Hz. That number is 0.84. That means, this size/grade of Rockwool absorbs 84% of the sound falling on it at 125Hz - an impressive result. Now compare that with 100mm of the Basotect here. As the blue line is 100mm thick, follow that left to 125Hz and read off the absorption. Let's say it is 0.15, which means 15%. There is no contest between these materials: the same thickness of Rockwool is about six times more effective at absorbing 125Hz which is why it is the only solution at low frequencies. That's why studio designers use it as I showed in the picture.

                  When considering absorption efficiency of a material, you only have to look at the manufacturer's published results table or graph v. frequency. That tells you everything you need to know. If no data is available, walk away.
                  Alan A. Shaw
                  Designer, owner
                  Harbeth Audio UK

                  Comment


                  • #24
                    Got it!

                    Thank you Mr. Shaw, this time I got it.

                    regards

                    Comment


                    • #25
                      Room tuning voodoo

                      OK.

                      Incidentally, the absorption coefficient tables/graphs are the standard way for acoustics people to compare the efficiency of various absorption methods (not scattering, absorption) according to thickness and frequency. This data is widely, internationally used when designing homes, public places, concert halls and studios. Even if you don't speak English, you can read .... 125Hz, 0.85 .... and that tells you everything you need, except for cost and cosmetics.

                      From time to time various 'room tuning' voodoo gadgets appear on the market. They usually have a romantic sales story. They include mystical bells the size of an egg, magic crystals, cosmic ray neutralisers and the rest. The fact is that the absorption coefficient of these (hard) devices is certain to be zero so they cannot have any meaningful influence on the sound in the room. Why do people throw themselves at these products when inspection of just two numbers - absorption coefficient (or percentage absorption, the same thing) and frequency can comprehensively describe their entire acoustic (non-) performance?

                      Professional acousticians think that the audiophile who is suckered into believing in such self-evidently non-functional products is a complete idiot. If these tweaky products actually worked, acousticians would be able to save their architect clients the cost and weight (and cosmetic impact) of Rockwool and could transform the acoustics of a public lavatory into that of a great concert hall for very little time, money and effort.

                      Simple, common sense rule of thumb:
                      • To absorb sound the absorber must be fibrous, or a combination of a (semi-rigid) skin + fibrous + air gap
                      • The thicker it is the more sound it will absorb.
                      • The more dense it is the more low frequencies it will absorb (but it may be more reflective at higher frequencies)


                      Below is an article from a studio magazine which gives a hands-on guide to DIY absorbers. NOTE! In this article the absorber panels do not cover much of the total surface area of the walls. This means that their absorptive effectiveness will not be great in the lower frequencies. Also note that the Rockwool used is only 30mm thick. If you look-up the absorption coefficient of 30mm Rockwool again here, the second line in the first table (703 plain 25mm is the nearest to 30mm), then following along to the 125Hz column gives a figure of 0.11 - virtually useless - compared with the previous 0.85 for the 100mm thick material (previous post) at 125Hz. With thin absorber material you just cannot absorb low frequencies - that's physics.

                      >
                      Attached Files
                      Alan A. Shaw
                      Designer, owner
                      Harbeth Audio UK

                      Comment


                      • #26
                        DIY absorption

                        The DIY thing appeals to me - I don't believe you need to spend huge amounts of money on sound absorption. Rugs, carpets, lined curtains, wall hangings and the judicious use of duvets have always been my line of attack when installing systems in troublesome rooms.

                        Comment


                        • #27
                          solution, just a sugestion

                          Dear Mr. Show and hifi_dave,

                          I do some research over the net and find, I hope, god compromise between function and esthetic of room acoustic elements. As you can see on this link:

                          http://www.recordingstudiolondon.co.uk/acoustics

                          product called 'walls' is able to reversed or remove very easily. During the listening sessions absorbing material (Rockwool) is on the 'room side' and all other time I can turn it to the wall and get nice looking wood 'sculpture'. Please, am I done a good 'homework' and what is the best place/area of application of this product (DIY, of course)?

                          regards

                          Comment


                          • #28
                            My experience, now fabulous after room adusting

                            Hi. I just came across this thread.

                            It took me a lot of tinkering to make my 40.1 sound "great" rather than "good". I too was having bass "boom" issues and a recessed midrange. It was driving me mad!

                            The way I got round this was:
                            1. position my speakers according to the Cardas method.
                            2. measure the frequency response of my room using the Rives audio test tones and radioshack spl meter. I then adjusted the seating position to get the best response.
                            3. treat the 1st, 2nd, ceiling and floor reflection points (to the best of my ability) and use bass traps (although, I'm not convinced they make that much difference).
                            4. I have also added some absorption directly behind the listening position. The seat is a bit close to the back wall, but this is where I had the flattest frequency response.

                            Now things sound fabulous (without going into the normal audiophile descriptors).

                            Good luck!
                            Attached Files

                            Comment


                            • #29
                              Damping

                              Just try to put one matress behind the speakers (initial setup) before make any investment.

                              Comment


                              • #30
                                The Cardas method of speaker placement?

                                Originally posted by teddyboy View Post
                                ...position my speakers according to the Cardas method...
                                Hi,

                                Is there anyone that can explain to me the "Cardas method"?

                                Thanks,

                                Sébastien

                                Comment

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