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Feb. 2018
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Classic or new Quad amplifiers and Harbeth speakers?

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  • Classic or new Quad amplifiers and Harbeth speakers?

    I'm wondering the new Quad amplifiers (Quad QSP,QMP and Quad Elite preamp) can perform same and trusty way like the legendary Quad 405?
    Quad QSP and QMP use the current dumping technology,but I'm not sure is any benefit or better results when the power amplifier work separate with two monoblocks.

    I compared few details from specifications.
    output power: 260W vs 140W
    frequency response: 10Hz-50kHz vs 10Hz-29kHz
    input impedance: 15kOhms vs 10kOhms
    total harmonic distrortion: 0,005% at 100W vs 0,004% at 100W

    Quad QMP use 4 toroidal transformers when QSP have only 1. My only concern is the 4 toroidal transformers maybe generate more buzz or noise.

    If I want to follow Alan:

    "Just about anything providing it has adequate power, good noise and distortion performance, can't be driven into clipping, has good features and facilities, decent after-care and represents good value for money"

    Do I need to choose the stereo power amplifier or mono power amplifiers? Anyone compared or use the Quad QSP or QMP with Harbeth speakers?

  • #2
    Increased cost for what?

    The QSP is mostly the same as the 606-2, 707 or 909, i.e. a 405 on steroids, with i.a. a toroidal power supply. Output is 2x140 watt rms.

    The QMP is a bridged version, with 1x260 watt rms output. Interestingly Quad decided to give it two transformers rather than one (and a different case), so you do indeed end up with four transformers.

    I donīt know why they did this, and why here and not in the QSP. It must have added quite a bit to the tooling cost for an otherwise probably low volume product. I think the only practical advantage of the QMP will be that two of them have much more power than just one QSP. So I guess it depends on whether you believe you need and can use more power.

    One other difference is that the QMP also has a proper XLR connection.

    Comment


    • #3
      Quad demo

      Originally posted by willem View Post
      The QSP is mostly the same as the 606-2, 707 or 909, i.e. a 405 on steroids, with i.a. a toroidal power supply. Output is 2x140 watt rms.

      The QMP is a bridged version, with 1x260 watt rms output. Interestingly Quad decided to give it two transformers rather than one (and a different case), so you do indeed end up with four transformers.

      I donīt know why they did this, and why here and not in the QSP. It must have added quite a bit to the tooling cost for an otherwise probably low volume product. I think the only practical advantage of the QMP will be that two of them have much more power than just one QSP. So I guess it depends on whether you believe you need and can use more power.

      One other difference is that the QMP also has a proper XLR connection.
      Thanks Williem.I'll try to find some Quad demo. I think the QSP and QMP toroidal transformers is very different. How noise is -or not- the 909 transformers?

      Comment


      • #4
        Quad QMP power supply

        Originally posted by willem View Post
        The QSP is mostly the same as the 606-2, 707 or 909, i.e. a 405 on steroids, with i.a. a toroidal power supply. Output is 2x140 watt rms.

        The QMP is a bridged version, with 1x260 watt rms output. Interestingly Quad decided to give it two transformers rather than one (and a different case), so you do indeed end up with four transformers.

        I donīt know why they did this, and why here and not in the QSP. It must have added quite a bit to the tooling cost for an otherwise probably low volume product. I think the only practical advantage of the QMP will be that two of them have much more power than just one QSP. So I guess it depends on whether you believe you need and can use more power.

        One other difference is that the QMP also has a proper XLR connection.
        I asked Quad why there are two transformers. This was the answer:

        The QMP have one dedicated transformer for the supply to the amplifier boards and a separate transformer to provide plus and minus 15 volts and 12 volts to other areas of the circuit.

        Comment


        • #5
          Real benefit?

          Originally posted by willem View Post
          I asked Quad why there are two transformers. This was the answer:

          The QMP have one dedicated transformer for the supply to the amplifier boards and a separate transformer to provide plus and minus 15 volts and 12 volts to other areas of the circuit.

          Thank you.I don't know what does it mean in real world.Can I get more control,power reserve and much more room before the amplifier start to clipping?
          I'm curious what is Alan opinion regarding the power amp Quad QSP vs monoblock power amp Quad QMP?

          Is it any real benefit like better frequency response,lower noise floor,more current in Quad QMP?or just waste of money?

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          • #6
            Just more power - if needed

            You get 2 x 260 watt instead of 2 x 140 watt. That is all there is to it (the other small differences will be inaudible). If you play big insensitive speakers in a large room you may need the extra watts. They are a waste of money of you play P3esr's in a small room.

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            • #7
              Power at your finger tips

              Originally posted by willem View Post
              You get 2 x 260 watt instead of 2 x 140 watt. That is all there is to it (the other small differences will be inaudible). If you play big insensitive speakers in a large room you may need the extra watts. They are a waste of money of you play P3esr's in a small room.
              If the only different is the extra power then Quad QSP is better deal.Probably 2x140W is plenty enough. I found Alan opinion.I hope is still valid.

              "300W is a huge - really massive - amount of power. But you are in control of that power. It's your hand on the volume control. You will probably only ever need 50-100W (peaks) of the 300W available."

              Comment


              • #8
                Switch off plop

                I bought QUAD QSP and Elite preamp.When I switch on/off I hear some noise -like thump?- from speakers.Is it normal in QUAD amplifiers?
                Could this damage my Harbeth speakers in long time period?
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                • #9
                  Also 606

                  My 606-2 also makes a little pop when switched on. It does not worry me, but my wife thinks it is inelegant. Apparently it is part of the design. The 606-2, 707, 909 and the QSP are all fundamentally the same design. The 606 (mk1) was different in that it had a traditional transformer, and differs in a few details as well.

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                  • #10
                    Quad plop?

                    Originally posted by szigony View Post
                    I bought QUAD QSP and Elite preamp.When I switch on/off I hear some noise -like thump?- from speakers. Is it normal in QUAD amplifiers?
                    Could this damage my Harbeth speakers in long time period?
                    [ATTACH=CONFIG]3895[/ATTACH]
                    (1) Normal
                    (2) Good choice - Robert at KJ spoke very highly of the QSP, after I told him I already had 909.

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                    • #11
                      Turn down volume first

                      Originally posted by willem View Post
                      My 606-2 also makes a little pop when switched on. It does not worry me, but my wife thinks it is inelegant.
                      My old nait 3 has always made and off/on thump, and yet a pro high powered crown amp is silent when it comes on/off, I always ensure the volume is down at turn off in either case.
                      Getting to know my C7ES3

                      Comment


                      • #12
                        Power thump common

                        My Quad's thump, my Plinius thumps, my Inca Tech Claymore (pre-Naim Nait) thumps. Personally, amps are first on last off.

                        Comment


                        • #13
                          No problem

                          Great.Thank you.I always off the volume when I turn off.

                          If "thump" is not problem/safe for the speakers then I'm happy to use QUAD amplifiers.

                          Comment


                          • #14
                            Correct power up/power down sequence

                            Originally posted by ssfas View Post
                            Personally, amps are first on last off.
                            I suggest amp should be turned on last and off first. If the amp is still on when the preamp is turned off any noise caused by the preamp or anything else further up the chain will be amplified by the amp.

                            Comment


                            • #15
                              Power-up/down sequence

                              Originally posted by Don Leman View Post
                              I suggest amp should be turned on last and off first. If the amp is still on when the preamp is turned off any noise caused by the preamp or anything else further up the chain will be amplified by the amp.
                              That is the procedure proscribed in the owner's manual for my Rogue Sphinx Integrated. All other devices on first, then the IA. IA off, then other equipment.

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