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"Amps all sound the same" (more or less)

Discussion in 'audio' started by Columbo, Aug 31, 2020.

  1. Tony L

    Tony L Administrator

    I suspect it was a combination of things, e.g. the remarkably clever design of the 303 meant it was all but indestructible even with the fragile transistors of the day (you can even short the outputs without hurting it), and secondly pretty much every loudspeaker on the market had been designed using valve technology (obviously including the ESL) so are voiced to expect a little output transformer impedance and sound ‘wrong’ without. The 303 sounds superb with similar-vintage Tannoys etc and is one of very few solid state amps I can cope with driving classic Klipsch horns, which are unquestionably SET-era loudspeakers. The things the 303 really can’t do at all, e.g. deal with anything much below a non-reactive 8 Ohm load largely didn’t exist in 1967. The haters always try to compare it against a modern amp into modern speakers!
     
  2. Robert

    Robert Tapehead

    My take on this after many years of listening and deliberation is to expand the thread title into:

    Most amplifiers sound more or less the same, most of the time.

    What do I mean by most amplifiers?
    Well, the typical SS stuff churned out by the likes of Audiolab, Cambridge, Cyrus, Pioneer, Technics, Quad, modern Naim, it's a long list.
    They all measure well in all key area and lack significant quirks.
    Most loudspeakers these days are fairly benign loads though tend to to sit in the 4-6 Ohm region these day. Power is cheap.

    So you take the typical integrated amp and the usual boxes from Mission, MA, Elac, etc and the results are boringly predictable.
    Sonic differences between amplifiers on line sources will usually be inaudible, especially under the conditions in which most of us evaluate and compare.

    But that's not the whole story of course, and to horribly paraphrase the late Peter Walker - it's the interface, stupid!

    A couple of examples.

    Tube pre-amp measures great in nearly all areas, low noise, low distortion, flat reponse. Has a 1.5K Ohm output impedance.
    I go for a demo and connect it to a power amp sitting alongside with a 50K Ohm input impedance via a 1m low capacitance cable.
    Sounds great, love it. I try it with a completely different but also excellent power amp, this one has 30K Ohm input impedance. Again sounds great and much like the first.
    This must be a good pre-amp and I've demonstrated it can sound excellent through two different power amps. I buy it and take it home.
    Connect it via 2x7m interconnects to my expensive Class A monoblocks, each with input impedance of 5K Ohms.
    Now it sounds weak, warm, rolled off and flat. Yuck!
    Loading is all wrong.

    It's the interface, stupid.

    Now I'm listening to a couple of integrated amplifiers via the phono input.
    Both highly competent designs, the only significant different being that one has a steep high pass 'warp' filter attenuating signals on the phono input <20Hz.
    I'm using a WTA turntable with Ortofon MM. I'm struggling to hear a different of any significance. Both sound like really good amplifiers.
    Now I swap the turntable and use a Rega turntable with a Grado cartridge. Suddenly it's night and day different. One amp, the one without the warp filter sounds really poor......
    The Grado in the Rega is compliance/mass mismatched just a little, and the combination is relatively undamped, sending significant <20Hz signal into the amplifiers.
    One amplifier is passing this merrily into my little ported bookshelf 'speakers and the bass drivers are dancing accordingly, modulating and distorting the wanted signal along the way, the other amplifier is not.
    One amplifier is now seeing significantly more power demand thanks to all of that subsonic crud, the other is not.

    It's the interface, stupid.

    You thought this was easy? :)
     
  3. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    .... and for the exact opposite view... I consider subsonic filters the work of the devil and never fit them. I remove them as one of the things I do in the Arkless 640P and GTI!
    I deliberately design all my phono stages flat to below 1Hz and fully amplify all the sub sonic crud. -3dB in fact usually around 0.1Hz.

    All my comments in this thread until this point have of course been entirely related to power amps which is where I consider the important differences are often underplayed.
    If looking at the whole amplification chain though then phono stages make huge differences and rarely sound the same as one another whilst line stages are the easiest to get right as they have bugger all of a task to do... In fact with modern high output level sources all that is required in most cases is a controllable way of throttling back the input signal rather than amplifying it.... ie a volume control!
     
  4. Tony L

    Tony L Administrator

    I don’t understand why you would consider heating up all too often hopelessly inadequate bass drivers with sounds they can not possibly reproduce in any way but turn into gross distortion is a good idea? There is nothing on a record below 20Hz other than warps and rumble, in fact you are lucky to get close to that on anything aside from say techno 12” singles etc.

    I understand filters are often a bad thing sonically, and some in audio kit is hopelessly intrusive (e.g. I never liked my spare Quad 34’s phono stage until Rob had a go at it as it clearly rolled off way into the audio band and sounded thin), but surely a well designed filter at about 10Hz is beneficial, especially for speakers like old Spendor BC1s etc where killing the bass units is relatively easy.
     
  5. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Firstly there is very little heating or power happening at these very low frequencies. They are below resonance of the woofer and hence it will flap around with only low power driving it in a typical ported speaker. Cone movement is much less anyway down there with a sealed box.

    The problem is that the frequencies we want to remove are just too close to those we want to retain. The very lowest frequencies on a record are roughly the same as the highest subsonic resonance issues from an arm/cart! ie around 16Hz (lowest note on a huge pipe organ). If a filter is to have substantial effect where it's wanted it WILL have an effect on the bass. If it is to properly remove the subsonics it will be as obvious as the one on the Quad 34.
    Change in phase due to such a filter begins to occur about 10 times higher in frequency than the actual roll off and any attempt to use high order filters to get as close to a brickwall filter as possible makes this non linear and much more severe, especially in terms of group delay. (I guess a digital filter done with DSP could make the ideal subsonic filter.... at the expense sonically and financially of having to convert everything from analogue to digital and then back again!)
    Hence subsonic filters almost always have some degree of audible bass roll off and worse still have a negative effect on the "texture" and "feel" of the bass and the slam etc.
    They can also involve extra circuitry in the signal path of course and in the case of a stock CA 640P an extra op amp is used to carry out the subsonic filtering.
    Choosing the right arm and cart with correct mass etc (and using silicone fluid damping, where available, for awkward cases) is a much better way of addressing things IMO.
     
    Seanm likes this.
  6. sq225917

    sq225917 Bit of this, bit of that

    I'm with jez, fix the cause not the symptom.
     
  7. Robert

    Robert Tapehead

    The cause is inaudible subsonic noise degrading the audible signal. You treat this first by addressing the mechanical problem, then the electrical if the mechanical doesn't do a good enough job.
    All vinyl sources no matter how well matched have this problem to some degree.
    But this is about a significant factor which can make two similar amplifiers perform very differently depending on the amount of subsonic noise coming from the source, not personal preference on warp filters.
    The solution to the preference issue is easy, it's called a switch ;)
     
  8. Tony L

    Tony L Administrator

    I remember many dems in the ‘80s of typical mid-sized ported boxes like the ES14, 770 etc watching the bass unit flub in and out by 2cm or more due to warps, footfall etc. I know this can be hugely reduced by getting the arm/cart math right, and I certainly pay attention to this (plus I have huge speakers with stiff surrounds that do not fear bass in the slightest), but get it wrong, as so many people do, and the midrange is coming from a hopelessly moving target.
     
    sideshowbob and Robert like this.
  9. Joe P

    Joe P certified Buffologist / mod

    Tony,

    Yup, when I had Royd Sorcerers record warp was a genuine concern. If a record was hilly enough, I could hear the Royds flapping away and about to run out of throw.

    I think record warp is much more of an issue with small, inefficient speakers because now that I have big, efficient Tannoys the drivers barely move at all even if a record is more warped out than the Enterprise was in that episode when the emergency overload bypass had been sabotaged by a mysterious woman!

    (To prevent the ship from flying apart, Scotty had to manually cut the matter-antimatter fuel flow to the warp engines. He did it in just in time, too. The ship hit warp 14.1 (!!!) and after a few more seconds of that it would have exploded.)



    Aye, now that was some serious warp.

    Joe
     
    Darren, Martian Sunrise and Snufkin like this.
  10. Joe P

    Joe P certified Buffologist / mod

    Rob,

    What would you recommend to a person with vintage speakers, say Tannoys with Monitor Reds, if the person was interested in going SS?

    My Stingray is working great, but if it ever went pfffffft I'd want at least try a few SS amps.

    Joe
     
  11. sq225917

    sq225917 Bit of this, bit of that

    Flapping bass, not an issue with yams and my Paradise.
     
  12. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    I'm afraid I must once again disagree... in general anyway. Some low power SET's could feasibly suffer core saturation of the OPT's which would indeed be very bad for SQ and a tiny number of badly designed valve amps could have LF instability in the feedback loop provoked by it but I struggle to think of much else in the way of scenarios where it would make any difference. SS direct coupled amps which make up the vast majority of those in use will be unperturbed by it and it's likely that the sometimes alarming looking woofer movements from subsonics in a shoe box size ported speaker are due to maybe 1/2W of power as there is no damping of the woofer movement below resonance.

    Doppler distortion due to the woofer movement is of course the speakers doing rather than the amps but I can't say I've ever noticed it in practice, which doesn't mean it doesn't exist, I concede, just that IME it doesn't seem particularly relevant. The worst I've seen is certain small ported speakers that just don't seem to be able to handle such large excursions as well as the average such speaker making audible port chuffing noises. Obviously the "mechanically insensitive" or inebriated could get heavy handed with the vol control and get the woofer bottoming out!
     
  13. Robert

    Robert Tapehead

    Hi Joe,

    I'd echo what Tony posted up-thread and try a Quad 303.
    The capacitor coupled output does seem to avoid drying out the LF on some vintage 'speakers

    Otherwise lots of vintage Marantz and Pioneer from the early 70s had cap coupled outputs and higher output impedance in general than modern SS amplifiers.
    Things like the Marantz 2030 receiver or 1030 amplifier, or a Pioneer SA700/800.
    They sold by the boatload back in the day so good examples are fairly easy to source - and they look gorgeous IMO.
     
    Joe P likes this.
  14. sideshowbob

    sideshowbob 47 Lab Rat

    Quad 303 is a good answer to almost any old-school speaker question. Always worth having a spare lying around.
     
    Nic Robinson and Joe P like this.
  15. Joe P

    Joe P certified Buffologist / mod

    Thanks, Rob.

    I was hoping you'd say, 'Joe you really ought to check out a Luxman L-550ax Mk II' if for no other reason than it looks so damn awesome.

    [​IMG]

    Joe
     
    JTC, Robert and sideshowbob like this.
  16. Joe P

    Joe P certified Buffologist / mod

    Ian,

    Are you still running old Tannoys?

    Joe
     
  17. sideshowbob

    sideshowbob 47 Lab Rat

    Of course. Mansfields with 15 inch HPDs. The room is the right size for Westminster Royals, but I've neglected being rich enough to afford them.
     
    Joe P likes this.
  18. JTC

    JTC PFM Villager...

    Joe: just stop it. I have its big brother coming for a play soon, and in a way I'd really rather it weren't, as I have a horrible feeling it might be difficult to pick between it and...

    [​IMG]

    I think the Luxman is the more attractive to look at and may well be the better sounding, but so it should, being new and nearly 3x the price I paid for the 2275. And that Mac is everything it shouldn't be: fast, fun, very detailed, extended top and bottom and very easy to live with (if not lift, being nearly 40kg). Before I bought it, I read almost everything out there on the web about it and the Luxman, and the MA2275 has a fair number of detractors, saying it's 'dark sounding' or 'boring' or 'plodding'. Total rubbish. It's terrific. But, I did say that plan was to buy that 'final' amp, and the Luxman class-A can is calling out to be opened...

    (I am hoping Shrink of these parts, and the ex-owner of the MA2275, will be along to either lament the sale of his Mac or reassure me that his new Luxman blows it into the weeds - I want a clean victory, one way or t'other - preferably to the Mac as (a) I own it now, and (b) I'd have to dig deep to buy the Luxman. So the contender ought to deliver a knockout blow, a decisive win as it were, to justify its three-fold cost. Otherwise, it's very tempting to just settle in with my (apparently requisite) pipe and slippers, and enjoy the cosy un-hifi dentist audio world I now seemingly inhabit. Open wide now.... ;)
     
  19. Joe P

    Joe P certified Buffologist / mod

    John,

    Don't worry. A Luxman L-550ax Mk II isn't in the cards here. I just mentioned it because Luxman came up in another thread so I did a quick search to see what the amp was.

    Damn, that's a nice looking amp, and probably awesome too sonically, but things are too uncertain at the moment to drop that kind of cabbage on a toy when I have a perfectly functional toy. That said, if the Luxman is the clear winner it would be good to know.

    Joe

    P.S. On looks alone, I'd go Luxman over McIntosh, but appearance is even more personal than sonics. If you can believe it, some people think the Stingray looks weird. Well, I never...
     
  20. JTC

    JTC PFM Villager...

    I agree - the Luxman wins it on aesthetics and seemingly on build quality as well (not that the Mac is any slouch and is built very, very well). Sonically, only time will tell, and my money is on 'different' rather than one being 'better' than the other per se. The Mac's very listenable and though I am sure I still need to adjust a bit to a slightly less 'valvey' sound (as compared to my EL34-based EE amp), it has more detail and extension on both ends, albeit not in an obviously 'tilted' way like some hifi is.

    I am probably playing a foolish game by even letting the big Luxman in the house, but the dealer is very persuasive and he has a super deal should I decide to trade my EE in against it. I'd then have to sell the Mac on of course, but I am very taken with it, for all its oddball 'physician's home den' looks and heft. My kids think the EE looks nicer, and would probably say the same about the Luxman too. But, y'know, one thing we can agree on is that the Mac kit is definitely *distinctive* among hifi brands, both in approach and aesthetic. I'd never, ever, have predicted I would like the amp based on some of the (frankly bizarre) comments I've read - if this thing is 'dark' I would HATE to hear what they consider to be 'normal' - ear-searingly aggressive treble can't be a good thing, no? The Mac just sounds like music, nothing added nor taken away, at least into the easy-to-drive, impossible-to-fluster Ardens....
     

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