Announcement

Collapse

HUG - here for all audio enthusiasts

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.

That's it! Enjoy!

{Updated Oct. 2017}
See more
See less

P3 and the 300B type tube amplifier

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • P3 and the 300B type tube amplifier

    Does any person ever try this combination ? I have a P3, want to buy a tube, some person suggest --- 300B . Does anyone have experience on this combination ?

    {Moderator's comment: what is the power output of the 300B?}

  • #2
    The 8W amp and a modern speaker

    As you consider using a very low powered amp for a Harbeth I suggest you read this:
    http://www.harbeth.co.uk/usergroup/s...all-an-amp-%29

    It is there where you can read from the designer Alan Shaw himself that you should not consider using low powered amps (no matter what some people say about these combinations) cause they will bring the tendency to compress the signal or run into (sometimes even inaudible, but still existant and disturbing the signal) clipping.

    You will read dozens of suggestions everywhere on the net. But I strongly believe that Mr. Shaw knows what he is talking about. Therefore I consider this as very substantial reason NOT to use an amp below (as stated from Harbeth themselves) 15 watts per channel.

    So why not look for an easily accesible amp of around 30 watts and never have a power problem at all instead of intentionally using an 8 watt amp and doubtlessly get distortions and a compressed signal?

    Comment


    • #3
      Flea-amps need SUPER-sensitive speakers

      Originally posted by thurston View Post
      It is there where you can read from the designer Alan Shaw himself that you should not consider using low powered amps (no matter what some people say about these combinations) cause they will bring the tendency to compress the signal or run into (sometimes even inaudible, but still existant and disturbing the signal) clipping....
      Not only does the P3's designer caution about the utter unsuitability of modern, low efficiency speakers (i.e. 99.9% of hifi speakers on the market now) he is not alone: even the amp reviewer confirms this point here.

      To quote:

      A meishu sounds 'miserable' in a system which doesn't suit this amp. Before buying this amp you should consider very, very carefully which loudspeaker you connect on it's terminals. Forget about connecting loudspeakers which are less sensible than 94dB [efficient]. And once you have heard how beautiful this amp performs on a 98dB or even better a 104dB loudspeaker, you will understand my statement that a 94dB loudspeaker in fact is too less sensitive to achieve an optimal performance.
      Is it crystal clear what is being said here? Is there even a flicker of doubt that such a tiny amount of power is unsuitable for a modern, low-efficiency, high-quality speaker?

      The would-be micro-amp consumer needs to take on board and accept the physical facts of the universe .... the P3, just like the LS3/5a, has an efficiency of about 84dB. I repeat - 84dB. The reviewer, correctly, identifies that such an amp needs to be coupled to a very high efficiency speaker. Needs to be. It's not optional. It's mandatory. Something like a big horn speaker driven from a paper cone drive unit. Such a tiny amp needs to be used with speakers of over 98dB or even more sensitivity. That's an almost unbelievably high speaker sensitivity rating. That super-sensitivity preculdes not only all and every Harbeth speaker, but I cannot think of one single speaker in current production from any major European brand that would approach that sensitivity. I, and I suspect most of my contemporaries, wouldn't have the skills to grapple with the design steps needed to achieve that super-efficiency, and would be in a state of anxiety wondering what sonic sacrifices would have to be accepted to chase the efficiency dream.

      That is the top and bottom of the matter. You can try all you like to talk-up flea amps in spite of the physics but unless you have a super-high efficiency speaker coupled to it, you are doomed. You will not be able to create enough clean loudness with it coupled to 'normal' speakers to allow yourself a satisfying musical experience. Plus, the poor amp will be under such strain to provide current to the normal speaker that it will generate plenty of unwanted distortion and, most likely, shorten its service life. I am not a physicist, nor an academic, I am just a simple speaker designer. But what a lifetime dabbling with audio has proved to my complete satisfaction is that you cannot, ever, beat physics and a little bit more thinking time and basic desk research always overcomes wishful thinking.

      Can we finally rest this daft subject because flea-amps and modern speakers are unsuitable partners - period.

      Want an amp that actually does the job and has a credible amount of power available? Treat yourself here and be done with the whole issue. I have two of the earlier non-USB SRA-150s and they are very nice. I checked the input sensitivities yesterday and the aux/CD/DVD can all take 2V (CD full output) with ease and the output stage only clips with a fully modulated CD when the volume is at 47 out of 63 max. Plenty of overload margin and drives P3ESRs well. Of the money you save, how about giving a proportion to charity, put some in the pension pot, have a good holiday and get some great seats at the concert hall and you will have far, far more long term satisfaction! Guaranteed.
      Alan A. Shaw
      Designer, owner
      Harbeth Audio UK

      Comment


      • #4
        What glitter?

        That will be a very hard test for the man asking the question in the first place:

        Wanting advice about an exotic multi-thousand dollar device and getting the aswer that it does NOT work. Instead a basic 105,- British pounds-machine does the job PERFECTLY instead.

        I fear this will not satisfy the need for luxury and glitter because it is only (!) rational.

        Mad world.

        Comment


        • #5
          Compromise - a tube with enough power?

          Alan's advice is clearly on point.

          However, just in case zhengzg is not quite ready to go quite so far so fast, and is dead set on having a tube amp, there is also the option of at least buying a tube amp with a decent amount of power (e.g. Rogue Audio, Audio Research), which would still be cheaper than a Meishu, and would at least be able to drive a Harbeth half-decently.

          Comment


          • #6
            8W - you can't listen loud

            This opinion does not go down well here. I present it as subjective and to provide some balance.

            I use my 800 Separo e300i 8W 300B valve amp with my P3s with beautiful results. It knocks my 1980s ordinary transistor amp for six.

            Open admission - don't have a modern ordinary amp to which to compare it at the same time, but I did once. Not a vialid comparison, but there it is.

            I advise only one thing. Secure a home demo or ask of the return policy and listen for yourself at home.

            And of course, realise the limitations of 8W. You can't listen loud.

            Apologies if this is not the board in which to make such comments.
            Ben from UK. Harbeth Super HL5 owner.

            Comment


            • #7
              Originally posted by BAS-H View Post
              ...And of course, realise the limitations of 8W. You can't listen loud.
              Forgive me, but I though a primary requirement of high fidelity sound at home was to approach real-life loundess. 8W is totally inadequate to do that with modern speakers. So, I'm curious as to what place in a truly high fdelity replay system (which frequently needs tens or or even, occasionally 100W+ of power on tap) a tiny amplifier with inadequate power reserve plays in achieving the high fidelity goal.

              This is, with respect, not a matter of opinion. We are dealing here with matters of fact. Physics is about energy, and energy is a factual subject. Speaker cones have mass (lots of it) and to get them accelerated from standstill they need power input. Lot's of it. We can determine how much power the long hand way by calculating moving mass, electro-acoustic efficiency, electrical watts in, efficiency ratios and so on. Or we can observe practically what happens when we couple a speaker to an amp and measure the sound pressure at our ears and simultaneously observe on an oscilloscope the clipped waveform of the amp at and beyond it's tiny power potential. If the amp is rated at 7 or 8W, it is irrelevent that it has (in the UK) a 13A fuse in its mains plug because it is taking as little power from the mains supply as a USB inkjet printer on standby, assuming no losses. Which I think you'll agree is a tiny amount of power. The amp cannot create power to move those cones out of nothing; the only available power source is the mains supply and if all that's been drawn-in from the mains is micro-power, one can't expect much sound output. A donkey can't haul a motor boat up a mountain.

              We can set on one side any positions we may have about amplifier sonics, about which we can agree to disagree. The facts of the matter are, uncomfortable though they may seem, that there is no substitute for power. And 8W is a minuscle amount of power: simply not enough to generate life-like sound waves in the room. That is exactly what you say yourself.
              Alan A. Shaw
              Designer, owner
              Harbeth Audio UK

              Comment


              • #8
                Low level listening

                Originally posted by A.S. View Post
                ...We can set on one side any positions we may have about amplifier sonics, about which we can agree to disagree...
                Fair enough. I also accept that a primary requirement of high fidelity sound at home is to approach real-life loudness; it's just that I prefer to listen to lower levels than that.

                I should have attempted to quantify. I've no dB meter so can't be exact, but it's pretty widely accepted that a normal conversation is about 60dB at one meter. To take some music with a relatively small dynamic range as an example, maybe something from the Four Seasons or the Water Music, that's about the level at which I listen, from two meters.
                Ben from UK. Harbeth Super HL5 owner.

                Comment


                • #9
                  Low listening level and audibility

                  Originally posted by BAS-H View Post
                  Fair enough. I also accept that a primary requirement of high fidelity sound at home is to approach real-life loudness; it's just that I prefer to listen to lower levels than that.

                  I should have attempted to quantify. I've no dB meter so can't be exact, but it's pretty widely accepted that a normal conversation is about 60dB at one meter. To take some music with a relatively small dynamic range as an example, maybe something from the Four Seasons or the Water Music, that's about the level at which I listen, from two meters.
                  60dB (or so) at 2m is an extremely quiet listening level, roughly equivalent to a modest-size mains powered transitor radio playing at the same distance. It would be easy to talk-over music reproduced at that level and to hold a fully intelligible conversation with someone in the room. At that level, 8W would almost certainly be sufficient, but turning the loudness up even a little will not increase the power linearly: the power requirement will jump far beyond the 8W available for even a perceptibly modest increase in loudness.

                  At that low loudness level you enjoy, many instrumental details of the orchestra will have dropped below audibility and human ears will only then hear 'the big picture', low level details and very soft notes won't be audible. That's nothing to do with the equipment of course, that's the way the ear works. I just started to look at that in the dynamic range thread. Clearly then, there is a practical limit to how much care/time/investment to make in the audio system because most of the claimed improvements in equipment reproduction quality are related both ends of the power range: in the microtonal detail and at high sound levels and the dynamic picture.

                  One may think that by reducing the volume (or using a small amp only capable of small volume) that somehow this is directly leads to increasing the resolution detail, finess or whatever you want to call it of your replay system. That would (I suppose) be a reasonable deduction based on the arguement that the ears were having to work less hard by not having all those nasty loud sounds to contend with. Unfortunately the opposite is true. I'll continue this on the dynamics thread now I've just conceived a way of explaing this.
                  Alan A. Shaw
                  Designer, owner
                  Harbeth Audio UK

                  Comment


                  • #10
                    More efficient Harbeth?

                    I suspect most of my contemporaries, wouldn't have the skills to grapple with the design steps needed to achieve that super-efficiency, and would be in a state of anxiety wondering what sonic sacrifices would have to be accepted to chase the efficiency dream.
                    Just for interest. What sonic sacrifies would we have to accept with more efficient Harbeth speaker?

                    Comment


                    • #11
                      Inertia and weight

                      Originally posted by Infobert View Post
                      Just for interest. What sonic scrifies would we have to accept with more efficient Harbeth speaker?
                      Good question.

                      Answer partly here. We'd have get out the precision weigh scales, disassemble a woofer, weigh all the parts and identify where the moving mass resides in the woofer assembly. One thing we'd inevitably conclude is that one of the heaviest parts of the woofer is the rubber surround. We know that rubber is heavy, and we know that the surround is a physically significant component in the woofer. So could we consider building a woofer without a conventional rubber surround. How about if we peel off the surround from a woofer and measure the frequency response. Is the surround acoustically beneficial in any way? It most certainly is.

                      From my archive, 2006 actually, I disassembled a KEF B110 (we were making drivers for KEF at the time), trimmed it a bit around the (PVC) surround and weighed it. You can see that it weighed 10.2g. That's a significant amount of weight that, when reproducing music, has to be thrown backwards and forwards thousands of times a second: a lot of inertia to overcome, and needing serious joules in the amplifier. We can save several grammes of that if we dispense with the surround and dust cap - see other picture. That would increase electro-in, sound-out efficiency. But ....

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

                      Comment


                      • #12
                        A watt is a watt is a joule - surely?

                        Originally posted by A.S. View Post
                        ... wondering what sonic sacrifices would have to be accepted to chase the efficiency dream
                        I am wondering what drives this dream - why is such super-high sensitivity so sought after? Given that we can readily deliver as much power as needed to a speaker whose distortion products are many times greater than those introduced by the amplifier, why has the need to drive a speaker to realistic levels with a few Watts become such a Nirvana?

                        OK, I can see a few legitimate needs when low energy use is essential, but here we have the irony that fashionable tube amplifiers are rather less good in this respect than their solid state peers.

                        Do people really believe that a tube Watt (or Joule) is louder than a solid-state Watt?

                        Comment


                        • #13
                          Watts and Joules

                          Watts are a measure of energy flow; I Watt is 1 Joule per second.

                          Comment


                          • #14
                            The romance of the micro-amp

                            Originally posted by Pluto View Post
                            I am wondering what drives this dream - why is such super-high sensitivity so sought after? Do people really believe that a tube Watt (or Joule) is louder than a solid-state Watt?
                            Strange it may seem to those with the equipment to reveal the true limited technical reality of micro-amplifiers, but there is indeed a romantic fairytale about tiny amplifiers and their wondrous sonics. It is pure fantasy; if the power available to a loudspeaker from the driving amplifier falls below the energising force needed to move the cones to generate a 'lifelike' sound, a lifelike sound cannot be generated and a clipped and distorted modified version of what the recording engineers intended will be the result. There can be no other outcome. Power is power. Donkeys cannot pull luxury yachts up hills.

                            Some listeners definitely do prefer a compressed version of reality and others do find harmonic distortion attractive. And yes, there are folk who adapt the word 'watt' to have not a rigid, universal meaning relating to forces and power, but to suite their argument.
                            Alan A. Shaw
                            Designer, owner
                            Harbeth Audio UK

                            Comment


                            • #15
                              "Some watts are more equal than other watts!"

                              Originally posted by A.S. View Post
                              Strange it may seem to those with the equipment to reveal the true limited technical reality of micro-amplifiers, but there is indeed a romantic fairytale about tiny amplifiers and their wondrous sonics. It is pure fantasy; if the power available to a loudspeaker from the driving amplifier falls below the energising force needed to move the cones to generate a 'lifelike' sound, a lifelike sound cannot be generated and a clipped and distorted modified version of what the recording engineers intended will be the result. There can be no other outcome. Power is power. Donkeys cannot pull luxury yachts up hills.

                              Some listeners definitely do prefer a compressed version of reality and others do find harmonic distortion attractive. And yes, there are folk who adapt the word 'watt' to have not a rigid, universal meaning relating to forces and power, but to suite their argument.
                              In hi-fi magazines and audio stores I've been told on several occasions that tube watts are more powerful at driving speakers than solid-state watts because they come from a higher current source, so the speakers work better with valves!

                              I was once looking at a pair of speakers in a shop and the salesman said they needed about 200wpc to sing properly, I told him my valve amplifier had 50wpc. He said that would be fine due to the reason given above.

                              I can see you pulling your hair out right now Alan!

                              Comment

                              Working...
                              X