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The Harbeth User Group is the primary channel for public communication with Harbeth's HQ. If you have a 'scientific mind' and are curious about how the ear works, how it can lead us to make the right - and wrong - audio equipment decisions, and about the technical ins and outs of audio equipment, how it's designed and what choices the designer makes, then the factual Science of Audio sub-forum area of HUG is your place. The objective methods of comparing audio equipment under controlled conditions has been thoroughly examined here on HUG and elsewhere and should be accessible to non-experts and able to be tried-out at home without deep technical knowledge. From a design perspective, today's award winning Harbeths could not have been designed any other way.

Alternatively, if you just like chatting about audio and subjectivity rules for you, then the Subjective Soundings area is you. If you are quite set in your subjectivity, then HUG is likely to be a bit too fact based for you, as many of the contributors have maximised their pleasure in home music reproduction by allowing their head to rule their heart. 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 only, although HUG is really not the best place to have these sort of purely subjective airings.

The Moderators' decision is final in all matters and Harbeth does not necessarily agree with the contents of any member contributions, especially in the Subjective Soundings area, and has no control over external content.

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{Updated Oct. 2017}
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New NAD Classics - bargains?

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  • #16
    Theoretically ....

    The C368 is an integrated amplifier and features a display for volume. the 'master rotary control' lacks an indent, so I'm assuming from a distance that this control has many if not infinite turns. If NAD have their electronic? volume 'law' properly and carefully designed, then despite having a very high sensitivity with everything flat-out, there should be more than enough adjustment there to allow sensible listening with a digital source, which is what most of us use these days...

    I remain deeply suspicious of the amp circuit and power supply used, but I'm a philistine you see and still suspicious of switching power supplies in any shape or form, so apologies where due.

    Comment


    • #17
      Signal levels

      You mean a digital source, like a cd, connected to the analogue input of the amp ?
      The amp should work perfect with its C 568 cd from same range, for that model it says: Output level Analog: 2.2 0.1 V

      But may be there are thinking people will use the digital output from the cd to connect to the amp, i dont know.

      Comment


      • #18
        Don't guess.... check

        Originally posted by kerouack View Post
        You mean a digital source, like a cd, connected to the analogue input of the amp ?The amp should work perfect with its C 568 cd from same range, for that model it says: Output level Analog: 2.2 0.1 V

        But may be there are thinking people will use the digital output from the cd to connect to the amp, i dont know.
        Not necessarily. Did you read the thread here about overloading amplifier (input) stages with high-energy sources like the 2v (2000mV) output from a fully loud CD?

        Background:

        Here


        Here

        We can collectively theorise and postulate until the cows come home, but the only way to be 100% sure about the source/amp match is by testing it and listening. The issue is not the amp/speaker interface (although that may be another issue) but the source amp input match. All you need to explore that is to burn a CD containing my WAV files with commentary put it in your CD player and listen. My video should make the process crystal clear. (Does any kind soul know where the video is of me testing various amps with the oscilloscope?)

        An investment of a few cents and half an hour and you will know for certain what the situation is. No test equipment other than your ears needed.
        Alan A. Shaw
        Designer, owner
        Harbeth Audio UK

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        • #19
          Thanks

          Thanks for the input Alan, sometimes it is difficult to decipher specs, I wonder in practice how gradually the sound level can be adjusted from no audible output to clipping.

          Dsrance, on switching power supplies (class D) amps I do wonder if in practice there is any performance disadvantage? Can the NAD be DBT and distinguished from one of their class A/B designs???

          Edit: Class D seems perhaps fashionable at the moment, a cool running pro power amp that weighs 8lb vs a hot 40lb (for a A/B) is advantageous when you are carrying stuff about but there seems to be a lot of class D hifi amplifiers on the market, some are only a bit lighter than you might expect for a similar powered amp with a big transformer.
          Getting to know my C7ES3

          Comment


          • #20
            Amp input clipping video

            Originally posted by A.S. View Post
            Not necessarily. Did you read the thread here about overloading amplifier (input) stages with high-energy sources like the 2v (2000mV) output from a fully loud CD?

            Background:

            Here


            Here

            We can collectively theorise and postulate until the cows come home, but the only way to be 100% sure about the source/amp match is by testing it and listening. The issue is not the amp/speaker interface (although that may be another issue) but the source amp input match. All you need to explore that is to burn a CD containing my WAV files with commentary put it in your CD player and listen. My video should make the process crystal clear. (Does any kind soul know where the video is of me testing various amps with the oscilloscope?)

            An investment of a few cents and half an hour and you will know for certain what the situation is. No test equipment other than your ears needed.
            https://www.youtube.com/watch?v=JSg32yJYY7E

            said video has been posted on youtube.

            {Didn't know that!}
            Getting to know my C7ES3

            Comment


            • #21
              Video links

              Originally posted by A.S. View Post
              All you need to explore that is to burn a CD containing my WAV files with commentary put it in your player and listen. My video should make the process crystal clear. (Does any kind soul know where the video is of me testing various amps with the oscilloscope?)
              I think the videos are in these two threads:

              http://www.harbeth.co.uk/usergroup/s...9740#post29740

              http://www.harbeth.co.uk/usergroup/s...boration/page3

              Comment


              • #22
                To be sure?

                Hello,
                I mean , "should" . But yes, we should try.

                1. A problem is I could not download the cd with the test tones from the other thread, it seems the files are not available in the server.

                2. Class d amps use less energy , if they sound equal why not use them? That does not mean changing your a/b amp , but that people with no amp buy the new class d.

                3. We should ask NAD cause right now almost all cd and streamers have digital output , so may be nad thinks we should use the digital input in the amp for that sources and the analogue inputs are there, with certain gain, to use it for certain sources. Or may be not, just and idea.

                4. Also is not always posible to try your amp or the amp you want to buy, with the cd or streamer that you have or you want to buy, also with your speakers in your room, to know if the volume before clipping is enough, that's why I would like to know which specifications would we need from the amp, and from the cd or streamer with analogue outputs, to be completely sure that will not be overload from the cd output to the amp pre analogue input, cause I think companies should give us that information.

                NAD specifications seem more complete than others, but still, what would we need ? To be 100% sure.

                Just for comparison purposes from Yamaha a-s700 specifications I read
                Maximum Input Signal
                PHONO (1 kHz, 0.019% THD) ............................ 70 mV or more
                CD, etc. (1 kHz, 0.019% THD) .............................. 2.2 V or more
                Is this what we need or is not complete ? That " or more " does not seem very specific but at least is something.

                Comment


                • #23
                  BAd luck with the new update from NAD.

                  Hello,

                  Thank you for your follow up note last week. i appologise tfor the confusion it caused.

                  I have retested a C368 regarding your report. The "Filters" and "Pre Out/Subwoofer" settings function as described in my last reply.

                  "Filters" setting:
                  - When the "High Pass" filter is selected, frequencies above 200 Hz are sent to your Speakers.
                  - When "Full" is selected, 20 Hz ~ 20kHz are sent to your Speakers.

                  "Pre Out/Subwoofer" setting:
                  - When "Pre Out" is selected, 20 Hz ~ 20kHz are sent to the PREOUT/SUBW RCA connections.
                  - When "Subwoofer" is selected, 40 Hz ~ 200Hz are sent to the PREOUT/SUBW RCA connections.

                  Therefor to send signals below 40 Hz to our Subwoofer, please set the "Pre Out/Subwoofer" setting to PreOut. Then you can set the crossover point you desire on the Sub's Crossover.

                  With regards to the first answer you received, the person that advised Jackie was not fully aware of the C368 Filter and Pre Out/Subwoofer specifications.

                  Please feel free to call me with any additional questions.

                  *****************************************MY NEW ANSWER:

                  Thank you very much for your explanation, i understand it, but i can not understand why NAD did that decissions.
                  1) I saw different subwoofers in a shop and all of then can go down in frecuencies more than 40Hz, so why the decision that the subwoofer out is between 40Hz-200Hz and not starting at 20Hz instead of 20Hz ?
                  2) Same subwoofers can be change their crossover from 50Hz - 150Hz, that means i could choose 100HZ, or 70Hz, or 150HZ, but it is imposible to choose 200Hz.
                  So if i want to NOT send ALL frecuenies to main spakers, which makes no sense using a subwoofer i choose Filter-high pass and i send 200HZ and up to main speakers, but then problem is:
                  A) I if select Pre out and send all frecuencies to subwoofer then i need to use crossover in the subwoofer, and the maximum can be 150Hz, that means frecuencies 150Hz to 200HZ will be sent to NO speaker! right ?
                  B) Other option i select subwoofer but then isend to subwoofer from 40Hz to 200Hz, so i will not send below 40HZ, not from 20Hz.
                  Thats why, the option you say, to use the pre out and use crossover in the Sub, is not a good solution, if one person selects filter-High pass is not good to use Preout (like explained in A) ) so needs to use Subwoofer option, and frecuencies from 20Hz to 40HZ will not be sent to the sub.
                  And if someone really wants a lot to send frecuencies 20HZ to 40HZ to the subwoofer, needs to use filters-FULL (if use filters-high frecuencies from 150HZ to 200HZ will not be sent to any speaker! like explained) and that means sending to the main speakers frecuencies that will be also sent to the subwoofer, what makes no sense, right ?
                  So i know now how it works, but i would like to know why the designers did that decissions, cause it does not make a lot of sense to me.
                  I must add: If i saw 5 subwoofers in a shop, and in all of them the crossver can be choosen from 50Hz to 150Hz, that means they are not designed to reproduce frecuencies from 150HZ to 200Hz so using NO crossover in the subwoofer and the option " Subwoofer" in the amp and sending that frecuencies from 40HZ to 200Hz (that includes from 150HZ to 200Hz) to the sub it seems makes no sense.
                  I must add: If i saw 5 subwoofers in a shop, and in all of them the crossver can be choosen from 50Hz to 150Hz, that means they are not designed to reproduce frecuencies from 150HZ to 200Hz so using NO crossover in the subwoofer and the option " Subwoofer" in the amp and sending that frecuencies from 40HZ to 200Hz (that includes from 150HZ to 200Hz) to the sub it seems makes no sense.

                  ***************************THEIR NEW ANSWER:

                  Hello Kerouack,
                  Thank you for your excellent feedback! All are valid points.

                  I have forwarded this support thread to NAD Director of Product Development. I have encouraged him to review the Filter and Subwoofer settings, and look into the possiblity of adding selectable high/low pass crossover settings.

                  I am hopeful the changes you highlighted can be implemented in a future firmware update.

                  Thank you again for the great feedback!

                  Kind regards,

                  Bob

                  Comment


                  • #24
                    Kerouak. Thanks for posting that update.

                    So that is very unusual, there is no doubt that will cause some issue for many potential users of the NAD amplifiers. None of it makes any practical sense and defeats the whole purpose of dividing the signal by not dividing the signal! I hope NAD can fix this with firmware as they say.

                    When I first saw the NAD units I was excited that they seem compact and well powered for a 2.1 channel AV system (HDMI modules) which is not common on the market, this crossover issue pretty much destroys that option as it currently stands.
                    Getting to know my C7ES3

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