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Biwire terminals and sound differences?

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  • #16
    Biwire terminals and sound differences?

    Hello Alan,
    When voicing the M30, I assume you used the brass jumpers supplied with the speakers. However, which set of speaker terminals did you connect the speaker cable to? The top or bottom pair? I've noticed a significant difference in sound between the two and was wondering which way the speakers were designed be used. Thank you very much.
    -Bill

    Comment


    • #17
      Biwire terminals and sound differences?

      Originally posted by Bill C
      ... which set of speaker terminals did you connect the speaker cable to? The top or bottom pair? ...
      Bill - During the entire design process I did not use any form of bi-wire arrangement at all - right up to the point of production, when for the user's convenience, the crossover was electrically isolated between bass and tweeter and connected to independent terminals on the rear panel.

      If you can repeatedly and definitely hear a difference then I am at a loss as to understand why and it needs serious investigation. It can not - repeat can not - be due to 27mm of brass bi-wire link. Of that I am absolutely 100% certain.

      Do bear in mind that when making A/B comparisons there must be no break in the sound you hear at all. Not even 1/10th of a second. If there is your brain will interpret the sound/no sound/sound as a change in frequency response. That's how our ears work.
      Alan A. Shaw
      Designer, owner
      Harbeth Audio UK

      Comment


      • #18
        Re: Biwire terminals and sound differences?

        Thank you Alan. There is definitly a difference in sound between using the upper and lower terminals. When I connect the speaker cables to the bottom pair of terminals, the sound is somewhat warm and laid back or non-fatiguing with very little "air" or high frequency energy. When connected to the top pair of terminals the sound is much more detailed with a great deal of high frequency energy and is a bit too bright and intense in my room. I tried removing the jumpers and used a short length of the same wire I use for the speaker cable (Regular 10g Belden Wire) to connect the upper and lower terminals. In this case the sound did not change between the top and bottom terminals, but retained that bright/intense sound on both. I have not tried bi-wiring. I can only conclude from this that the brass jumpers are influencing the sound of the higher frequencies. My room is small (10'X14') which is why I chose the M30's, thinking that the smaller speaker would be more suitable for my room. Thank you.

        Comment


        • #19
          Re: Biwire terminals and sound differences?

          I firmly believe that you are convinced that you hear a difference, so, for all practical purposes, there is a difference.

          But I can say, quite categorically, that providing the standard brass bi-wire links are clean and firmly trapped by the binding posts that there is no possibility whatsoever that driving the upper as opposed to lower terminals will make any difference to the sound - or the measurement for that matter. In the great scheme of things, considering the vastness of the universe and the dispersion of electrons through that unimaginable space, the last inch or so of brass can not and does not make a difference to the sound. Promise.

          I appreciate that this seems contradictory to what you have, and truly believe to have found. My point is that I don't disagree that you perceive a difference, but that difference is not from the bi-wire links or the selection of terminals but from some other, probably more mundane matter. It would pay you to really seek that out by diligent experimentation as you could so easily waste time and money chasing other bi-wire or connection links 'solutions' which may well degrade not enhance your listening.

          During the design phase of a speaker I have total disregard for the niceties of wire arrangements - the crossover is breadboarded, all the listening tests and technical work finalised, then fitted to a nice neat PCB and wired to the back panel's terminals accordingly. That formulae is then duplicated precisely in production, and there is neither measurable nor acoustic difference between the lash-up prototype (see attached rat's nest photo) or the final neat production PCB.

          That's how I find it; please double check and revalidate your results! There is an explanation for what you hear but it is not the one you think it is!

          I should add, that in the year since we introduced the HL Compact 7ES3 (which has been very successful for us) there has been not one single customer comment that we have deleted the bi-wire connections. But it has demystified this aspect of the design and simplified the user's set-up.

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

          Comment


          • #20
            Re: Biwire terminals and sound differences?

            Thank you for the quick reply Alan. I'm stumped. I also tried placing both speakers next to each other in front of my listening position, set the preamp to mono, wired one speaker to the top terminals and one to the bottom, and had someone switch back and forth from left to right speaker while I was blindfolded. I had no trouble picking which speaker was wired each way. The jumpers are clean (new) and seated properly as you suggested. I think my small room may exagerate the differences making them easier to discern. Anyway, I would be interested in hearing from others who have checked this with their speakers to see if it's just me. Thanks again,
            Bill

            Comment


            • #21
              Re: Biwire terminals and sound differences?

              Originally posted by Bill C
              I also tried placing both speakers next to each other in front of my listening position, wired one speaker to the top terminals and one to the bottom ...
              Ah, now this I understand. Although the two speakers are physically next to each other you would think wouldn't you that the sound from them should be identical. It's a real pity that you didn't have room measuring (RTA) equipment to hand because you would have seen for yourself on-screen that the frequency response as perceived at your fixed listening position will not be identical when you switch between speakers. In fact, the differences can be dramatic - many dBs - but somehow our marvellous ears can still construct a solid stereo image. For this reason, when I am working on a speaker design, I always have a Room Analyser system available, with a microphone near my listening point to see what the room is 'doing' to the pure sound from the speaker: it's always disappointing to see how normal rooms mangle the sound.

              So, I would personally discount that method of evaluation because you have unwittingly introduced a variable (speaker positioning) which will swamp by a million times any differences you may associate with the bi-wire links/terminals.

              The way I would investigate this is as follows: use one speaker, in mono, in a fixed position in the room. Fix yourself and do not move, not even an inch. You will need an assistant. At the speaker end of your existing hot/cold wires, make a Y splitter so that you can simultaneously plug into the top and also the bottom terminals. Use the same cable throughout or at the least use the same cable for both arms of the Y. Fit and tighten standard gold/brass bi-wire links. Connect to both the upper and lower terminals at the same time. Play music continuously. Ask your assistant to randomly remove one red plug (or black plug, or red and black plugs) from either the upper or lower terminals. If you are correct that there is a sonic difference between driving into the upper or lower terminals you will hear this difference as the signal is routed directly as opposed to via the bi-wire link.

              I'm confident that you won't hear any difference at all if you conduct the test as I have described. Whatever you hear - and I don't doubt your sincerity - is not due to connection but some other factor which you should chase.
              Alan A. Shaw
              Designer, owner
              Harbeth Audio UK

              Comment


              • #22
                Re: Biwire terminals and sound differences?

                Thanks Alan. I did consider the slight difference in position with the speakers side-by-side as well, so I tried switching the speakers position with eachother. The results remained the same each time. I'm probably not going to pursue the issue much further though. I'd rather be spending more time listening to music. I want to emphasize that I don't mean to infer that the speakers are at all bad sounding, only that they may be a little too resolving in a small room for me. Maybe with some room treatments I'll feel differently. Thanks again,
                Bill

                Comment


                • #23
                  Re: Biwire terminals and sound differences?

                  Hi Bill,

                  Given the choice I always connect the speaker wire to the lower (bass) terminals. My reason for doing this is not the result of any listening experiments as I don't think I've ever hooked things up to the top terminals or as some have suggested one to the top and the other the bottom.

                  My reasoning is the low frequency driver likely accelerates slower than the much lighter weight tweeter. Hooking up to the lower terminals means the signal has a shorter distance to travel than if you connected it the other way.

                  Having said all this, I know, given the speed electricity travels through wire, there is no rational reason to think my theory has any validity, but who says we have to be rational.

                  Regards
                  Don

                  Comment


                  • #24
                    Grafting on a subwoofer to M30

                    Update: I still find a difference between upper and lower terminals, but I've been experimenting with a sub which balances the sound out nicely. The M30's seem to do very well in my room now. That sense of excessive resolution or intensity is no longer an issue. Now if I can only get the sub dialed in properly, I'll be all set.

                    Comment


                    • #25
                      Re: Grafting on a subwoofer to M30

                      I think the secret of blending-in a subwoofer is to set the sub for a very subtle contribution - and no more. Often, subwoofers are set by their users to make too much contribution, and then the overall sound becomes murky and over-rich. The problem with that is that it can be addictive.

                      The lower in frequency that you blend in the sub the better as it will (probably) be less obvious. Don't forget that you need to make lots of experiments concerning where in the room to place it as well as adjusting its controls for best overall effect.
                      Alan A. Shaw
                      Designer, owner
                      Harbeth Audio UK

                      Comment


                      • #26
                        Re: Biwire terminals and sound differences?

                        Thank you Alan,
                        That's exactly what I'm finding. At first, I did have the sub turned up too much. It initially sounded warm and pleasant, but muddied things up a bit. Turning it down brought back the clarity and detail with deeper and cleaner bass.

                        Alan, do you feel that the 30's would benefit from high passing at 80Hz, or going with speaker level connections? Thanks,
                        Bill

                        Comment


                        • #27
                          Re: Biwire terminals and sound differences?

                          "I should add, that in the year since we introduced the HL Compact 7ES3 (which has been very successful for us) there has been not one single customer comment that we have deleted the bi-wire connections. But it has demystified this aspect of the design and simplified the user's set-up."

                          Alan,

                          1. I'm a little puzzled by the above statement. For the first time buyer of a non bi-wired Compact 7ES3, what is there to compare and comment about?

                          2. Also, having bi-wire connections for the SHL-5 and others, would it not be logical to advocate following through with an external bi-wire connection rather than to say that the brass jumpers would be just as good?

                          3. If bi-wiring is not de facto the superior connection, I don't see how its provision can accede to the convenience (as you say) of users in general. Surely, to connect two pairs of cables cannot be more convenient than one, particularly where there is only a single output point for each channel at the amplifier end.

                          Comment


                          • #28
                            Re: Biwire terminals and sound differences?

                            Never underestimate the resistance of the hifi consumer to change! Also, over the past 20 years or so since we adopted bi-wiring there has been a steady trickle of customers seeking detailed explanation and reassurance as to why their new speakers are fitted with not two but four terminals. That in turn leads to questions about the bi-wire links and so on. All of that distracts attention from the reason we are here: the high quality reproduction of music.

                            In the future, the provision of bi-wire links will be scrutinised model by model. This process started with the Compact 7ES3 as it was never my intention that the material, construction, length, colour or shape of the bi-wire links would ever be discussed, let alone become a focus of 'upgrade' attention. I made my position clear at the start: in exhibition situations where we wish our speakers to perform at their very best we have never used bi-wire connections, nor have any of our professional users such as the BBC. Nor have I at home. They were fitted solely to provide an option to customers who, in reality, ignore the option and use only one pair of terminals.

                            So my previous comment stands as reported.
                            Alan A. Shaw
                            Designer, owner
                            Harbeth Audio UK

                            Comment


                            • #29
                              Binding post holes

                              The question has been asked about the binding posts on all Harbeth speakers (as at Dec. 2007). I have taken a picture of what you will find if you unscrew the terminal heads as attached.

                              Note: Not all Harbeth speakers have biwire terminals as shown here, but the type of terminal posts is common to all.

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

                              Comment


                              • #30
                                The history of biwiring

                                It may interest some of you to know how Bi-Wiring became so fashionable in the UK..

                                As I understand it, in around 1985, Epos Acoustics originally proposed a three core connection in their earliest ES14 speaker - two positives, for the bass/mid and tweeter respectfully and with a common return (negative). This meant that three core mains cable could be used to advantage, linking the two "positive" connections together at the amp connection. A "Flat Earth" magazine "persuaded" them not to do it, because it was deemed a rubbish idea...

                                A few years later, a certain Scottish manufacturer launched a speaker where the back emf (or similar in the crossover) was so great that if the tri (!) wire connections were linked at the back of the speakers, gently pushing the bass unit caused the mid driver to move slightly too, despite no mechanical connection between them. Because this manufacturer had enormous influence in the UK back then, bi or tri wiring became the fashion. Dealers liked it too, because they could sell more cable and make a bit more money on the "sale." I can't say the benefits were huge, as a heavier gauge SINGLE wire did similar things for most speakers IMO.

                                Sorry my posts always seem so long, but to conclude, as Harbeth obviously takes (and has always taken) incredible care to optimise the crossover networks, a decent set of SINGLE terminals would do no harm at all and remove a potential user difficulty at a stroke. The only exception may *possibly* be in the 40.1, where bi-amping with decent matched amps *may* be a useful thing to do in certain circumstances(I know you'll put me straight on this Alan please...).

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