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HUG - here for all audio enthusiasts

Since its inception ten years ago, the Harbeth User Group's ambition has been to create a lasting knowledge archive. Knowledge is based on facts and observations. Knowledge is timeless. Knowledge is human independent and replicatable. However, we live in new world where thanks to social media, 'facts' have become flexible and personal. HUG operates in that real world.

HUG has two approaches to contributor's Posts. If you have, like us, a scientific mind and are curious about how the ear works, how it can lead us to make the right - and wrong - decisions, and about the technical ins and outs of audio equipment, how it's designed and what choices the designer makes, then the factual area of HUG is for you. The objective methods of comparing audio equipment under controlled conditions has been thoroughly examined here on HUG and elsewhere and can be easily understood and tried with negligible technical knowledge.

Alternatively, if you just like chatting about audio and subjectivity rules for you, then the Subjective Soundings sub-forum is you. If upon examination we think that Posts are better suited to one sub-forum than than the other, they will be redirected during Moderation, which is applied throughout the site.

Questions and Posts about, for example, 'does amplifier A sounds better than amplifier B' or 'which speaker stands or cables are best' are suitable for the Subjective Soundings area.

The Moderators' decision is final in all matters regarding what appears here. That said, very few Posts are rejected. HUG Moderation individually spell and layout checks Posts for clarity but due to the workload, Posts in the Subjective Soundings area, from Oct. 2016 will not be. We regret that but we are unable to accept Posts that present what we consider to be free advertising for products that Harbeth does not make.

That's it! Enjoy!

{Updated Nov. 2016A}
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How to make a $20 audio switch-over comparator Alan

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  • #16
    Resolutely sitting on the fence - pure textbook is not sufficient for satisfaction

    Originally posted by denjo View Post
    Do potential customers buy speakers based on measurements from scientific equipment and tools or is the purchase decision based on how the speakers actually sound in the listening room? This raises the question of whether scientific tools and equipment alone can be used or depended upon to design speakers or does it require some subjective element like the aural skills and abilities of the speaker designer?
    My view as a customer is that both are essential ingredients. A product that "sounds stunning" may only do so in the context of a particular system, listening room, or musical genre. Change any part of that, and suddenly that aspect of performance that seemed exceptional may now appear to be excessive.

    So IMO a commitment to measurably good performance is essential to long term satisfaction - you can change other parts of the system without the sound becoming unbalanced.

    On the other hand a "pure textbook" approach is not sufficient, not because some things cannot be measured, but because it is not cost-effective to develop the measurement techniques and instrumentation - and answer the question of how the engineer connects that data with the customer's perception of the system performance? And (again IMO) that is the place where subjective refinement of the design comes in.

    Maybe classical music is a useful example... the greatness of a composition is in the written music. Musicians add their own elements of interpretation and you and I may subjectively prefer different performances of a work - and while a great interpreter may be able to make something of a mediocre work, they will never be able to elevate it to the same rank as the greats.

    IMO one of the great could-have-beens of hi-fi is the story of Quad electronics... if Peter Walker had just added that subjective refinement step to the foundation of innovative concepts, ingenious industrial design, and endless serviceability it would have elevated their amps from very good to great.

    Comment


    • #17
      Subjective + objective in speaker design

      Originally posted by honmanm View Post
      My view as a customer is that both are essential ingredients ... a commitment to measurably good performance is essential to long term satisfaction ... (and) a "pure textbook" approach is not sufficient, not because some things cannot be measured, but because it is not cost-effective to develop the measurement techniques and instrumentation - and answer the question of how the engineer connects that data with the customer's perception of the system performance? And (again IMO) that is the place where subjective refinement of the design comes in.
      honmanm: I fully agree with your elaboration of the importance of subjective and objective assessments of a good speaker! Before I bought the SHL5, I studied the published impedance curves and noted the conservative sensitivity of the speakers, surmising that the speakers would be quite an easy load for my amplifier. The decisive factor was how it sounded in the listening room and my subjective impressions of the speaker's qualities.

      Comment


      • #18
        Originally posted by honmanm View Post
        ...IMO one of the great could-have-beens of hi-fi is the story of Quad electronics... if Peter Walker had just added that subjective refinement step to the foundation of innovative concepts, ingenious industrial design, and endless serviceability it would have elevated their amps from very good to great.
        What exactly do you mean? Are you suggesting that he added another step after the basic textbook engineering to take the design and "subjectivise" it?

        Suppose he didn't because he didn't want to. Or didn't believe in such a step. Or didn't trust his judgment.

        Maybe you could say that his resistance or disinterest in adding the magic dust was his reluctance to use marketing. After all, he could easily have said to the media (who would have believed him) that he had selected this component or the other for sonic reasons. I think it is a tribute to the man that he didn't waver from his principles. Did QUAD's anti-marketing cost the Walker family the business? Perhaps it did. All manufacturers have to walk the tightrope between what they truly believe behind closed doors in their boardroom or labs and what their customers want to hear them say. Very, very few suppliers feel able to discuss almost any subject in a public forum such as this. But actually, it makes very good business sense for users to know what they are 'buying-into' as the order book demonstrates.

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        • #19
          QUAD, speaker sensitivity and their remote control

          Originally posted by HUG-1 View Post
          Did QUAD's anti-marketing cost the Walker family the business? Perhaps it did.
          There may have been some of that. More likely two other factors.

          1. Loudspeaker manufacturers producing speakers with ever lower impedances and ever more crazy impedance/frequency curves, so the well designed Quads with bomb proof protection seemed not to be coping.

          2. The fiasco over the Quad 77 two way remote control. It was too complex and too quirky. I have one and every so often it crashes - I have to power down and re-set. The Quad 99 returned to a simpler one way remote, but the damage was done.

          Comment


          • #20
            The switchover box Mk3 - in uses, designing the C7ES3

            Two reasons for showing this picture again.

            First, it shows the situation in 2007 when I was designing the C7ES3 and couldn't decide between crossover design A and B. If you look closely, you can see that the components are somewhat different. Both measured equally well, but which sounded best*?

            Second, in conjunction with the picture of the rights hand side C7ES3, you get an idea of the tiny 'back bedroom' that I did most of the C7ES3 design work in. Obviously, it isn't a problem to actually use the C7Es3 in a small room.

            *I was most surprised to interview recently (to be uploaded one day) David Stripp ("Golden Ears" of BBC fame) who assured me that all the loudspeaker auditions that he'd been present at at BBC Research Dept. had been in - to best his recollection 20+ years later, single speaker mono. I was astounded. I have always worked and listened in stereo throughout the design phase despite the considerable inconvenience of having to make two prototype woofers, two cabinets, two crossovers and all the interwiring. I have subsequently discovered that many speaker developments cycles are in single speaker mono right up to the last day when the design is released and sold in pairs. We have two ears.
            Attached Files
            Alan A. Shaw
            Designer, owner
            Harbeth Audio UK

            Comment


            • #21
              C7ES3, small room

              Alan,

              Does the placement near the wall have a significant impact on the sound?
              I too have a small room (12x12x9), and I have my C7ES3's about three feet from the back wall.

              Dennis Girard

              Comment


              • #22
                C7ES3 in a smaller room - no problem

                Well, I think the success of the C7ES3 tells its own story. Yes, of course, the proximity of adjacent walls always lifts the bass somewhat, but that's not necessarily a bad thing if the response remains relatively smooth. If it worked for me in a small bedroom, then it certainly should work for you. What helps is that I have lots of books etc. throughout, so the acoustic is tolerable.

                BTW, I have recently re-written the User Manual and I've made more mention of speakers in corners and how to generally improve the room acoustics. We'll be changing to that version shortly, and at that point I'll make the new manual available on the website.
                Alan A. Shaw
                Designer, owner
                Harbeth Audio UK

                Comment


                • #23
                  Relay contact material

                  I must be missing something here, but it hasn't been possible to track down relays with mercury or gold contacts (there are mercury contactors, but those start at 35A and about 40!).

                  Common contact materials appear to be nickel silver (AgNi), silver tin oxide (AgSnO), and silver cadmium oxide (AgCdO). AgNi is a pale yellow colour, and the relays in the Velleman speaker protection kit are AgCdO. There are relays with gold-plated contacts, with current ratings around the 3A mark.

                  Here are 3 possible candidates (for comparison purposes, all same manufacturer and supplier, and DPCO type):


                  (for cable testing experiments the plan is to have remote relays at the speaker ends, hence 2-pole rather than 4 pole... unless once again I'm missing something).

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                  • #24
                    A great idea. I made Alan's relay comparator and it works

                    Reading about Mr. A. Shaw’s $20 audio comparator, I decided to build one, so that I can switch between two amps (driven from the same source component) on the fly, driving one pair of speakers, to detect any differences in sound. Very intriguing indeed…
                    I used 4 double FINDER 40.52 relays. Specs here: http://www.findernet.com/comuni/pdf/S40EN.pdf
                    Two of them used in connecting simultaneously the two amps (both hot and cold, eight contacts) to the speakers (four contacts) taking good care that left+ of each amp goes to left+ of the speakers, left- to left- and so on.
                    The other two relays provide a dummy load of 8ohm/60watt for each of the four channels in case that one (or both) of the amps are tube amps and isn’t safe to operate without a load. The dummy loads are inserted in the circuit in pairs independent from one another, when needed, by two twin switches (the red on the right side). They don’t affect in any way the sound, they are totally independent, and connected automatically to the amp (if I want to) which -at the moment- isn’t driving the speakers.
                    The relays are driven by 6 V DC, they are battery operated too, and I’ve added remote control with a simple on-off switch and 6 meters of cable.

                    When DC is OFF (relays free), amp 2 is powering the speakers and amp 1 nothing, or the dummy load (if engaged). When DC is ON (relays engaged), amp 1 is powering the speakers and amp 2 nothing, or the dummy load (if engaged). There is also a fan for keeping the power resistors cool (I never used it). In normal listening levels the resistors of the dummy load, if engaged, are becoming only slightly warm. This “toy” can also be used in the opposite direction to feed two pairs of speakers, each at a time, with one amp.

                    It works perfectly, you can’t even detect the gap in time between connect – disconnect when pushing the magic button! If a relay fails, nothing happens. There is no case that the one amp will be connected to the other one.

                    I’ve spent less than € 50 and a few hours of my free time on that. Who needs this toy? Perhaps no one. But still, it is fun to watch fellow music lovers, unable to identify their own amp when compared -on the fly- to a “lesser” or “better” one, or finding that differences between good, or decent if you like, amplifiers when playing music at exactly the same volume, are not easily / practically detectable / existing! (Use the words you like). Note that any time I gave a very slightly higher volume to an amp, it got all the votes hands down! (I’ve never used so far, a solid state amp vs a tube one, they were all ss). Now think, what makes a difference in sound reproduction at home.

                    A great idea Mr. Shaw! Amusing in many ways, and didactic!

                    IMG_0392.JPGIMG_0393.JPGIMG_0394.JPGIMG_0395.JPG

                    {Moderator's comment: You see for yourself .. the LOUDNESS difference is the real reason amps "sound different". It is as simple as that.}

                    Comment


                    • #25
                      Amsp sounding different - major reason

                      Excellent, Takis, thank you.

                      Moderator's comment: You see for yourself .. the LOUDNESS difference is the real reason amps "sound different". It is as simple as that
                      THE reason? No. The major one, certainly, but there are others. E.g., compare a reference amp with a valve amp with an inadequate output transformer, playing at a given SPL. One can reproduce the whack of a grand piano; the other can't. I'm afraid things aren't so simple!
                      Ben from UK. Harbeth Super HL5 owner.

                      Comment


                      • #26
                        Audio Comparator Question

                        Do you happen to have a schematic for the construction of this audio comparator?

                        Comment


                        • #27
                          Sorry darrylm,

                          I didn't see your post earlier. I hope this helps:
                          Attached Files

                          Comment


                          • #28
                            Relay performance

                            mechanical relays has this problem of bouncing (mechanical oscillation).

                            Comment


                            • #29
                              Break before make contacts - essential

                              Originally posted by coredump View Post
                              mechanical relays has this problem of bouncing (mechanical oscillation).
                              That is not an issue for switching audio.

                              One very important point ..... according to the circuit diagram it is possible that the output of the two amplifiers could be momentarily connected to each other and to the speakers. This could damage or destroy the amplifiers or even the speakers.

                              When selecting the relays to use be sure to buy 'Break before Make' and not 'Make before Break' contact types. This means that the swinging contact must positively disconnect from one contact before swinging to the other. It will ensure that the output from amp A is isolated from the speaker before amp B is connected to the speaker and avoid the two amps being briefly shorted together.

                              Comment


                              • #30
                                Close-up of the relay

                                Sorry - I really should have answered this one ages ago.

                                Attached you will see a close-up picture of the working parts of a relay. It's about 3cms long, and I've removed the protective case. Can you see that two of the contacts are rigidly fixed in place, but under the influence of a current in the coil, the centre contact can be influenced to move from the rest position. When the current is disconnected, it flops back to rest again.

                                About mechanical oscillation: as we are only operating a go/no go with a cycle of seconds or minutes, and the contacts are physically quite well separated, this really shouldn't be an issue.

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

                                Comment

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