Sound Quality Vs. Measurements

[nigel pearson]

Originally Posted by jacco vermeulen

Haven't you been involved with class D works, Mr Pearson ?

Yes I did with Gary Koh in the USA . Wish I had thought about shunt regulated . We came up with a nice fix for the power supply . I wont disclose how as Gary would be annoyed . All I will say is that the bus pumping is important .

The one big advantage of class A is that nothing is hidden . Mostly it works or it doesn't . With class B or D the power supply in pendulum fashion becomes part of what we listen to ( it swings between the incoming 230/115 V and the speakers ) . I think class B is the best of all if we can get high order distrotion sorted . The fact the class B power supply is not saturated is highly advantageous .

I suspect if anyone was looking at what I have just said about shunt and class D it will be important . Time will tell . Ideal shunt will behave like a lead acid battery with one exception . It will work to 50MHz ( a realistic requirement I feel even if it's the additional caps that do it ) .

For what it is worth class D and CD belong together . Give me Vinyl and big class B amps any day . 100W B 20 Watt A and 600Watts into 1 ohm ( burst ) . Perfection .

Philips Black Tulip . It was a very bad night with Monsoon rain , a very old taxi driver took me to London to see Black Tulip . When I refused they would have sent a helicopter , I gave in . I was involved in professional video so got an invite if audio also ( I think I provided a Philips VCR to one of ITV's directors { a Philips gift I think } and he was a music lover , I never asked why I was invited ) . Smoked my first Cuban Cigar at that do( the real ones today are not as good ) . Don't think we listened to any music . The old boy had been to Bristol after dropping me off and returned for me that night . If someone had said he was 100 I would have said perhaps . He kept saying about his new Volvo , that it had no carburetors . The smile was something you had to see when he said it . He must have been in Fiddler on the roof , he looked so right for that . I had one of those Volvo's ( 144 Einsprits ? ) for a while . I sometimes think my life is just one big film .

[dvv]

Originally Posted by jacco vermeulen

Goes way beyond that, imo.

Look around you.
Mr Wayne can only be American, Mr Veselinovic's amp flavor is rooted in the moderately liberal days of pre-1989.
(and Mr Yaniger, eeh....let's skip Mr Yaniger)

What would you have favored/listened to, if they hadn't fckd up your mind in France ?

Well, yes and no.

This is correct in at least aa part, perhaps even the bigger part, however it is true of only SOME amplifiers made before say 1990.

The reason for that is the reasoning that stands behind those products. In those days, the main effort what of making it all sound like one, no bass, no mid, no treble, but just one, hopefully seamless sound picture.

To make it come nearer to your neighborhood, I have some wonderful memories of Philips' gear from that period. For some 20 years, I owned a Philips N4520 open reel recorder (the damn big and heavy aluminium model, 28 kilos) which I was literally elated with. It just sounded so much better and wholesome than ANY Japanese model I ever heard, and I heard most of them, with the notable expection of a Sony model, I forgot its designation.

You may remember that inthose days, and that's say 1978-1982, reVox was king in Europe, NOTHING could touch it. Well, in 1981, German managize "Stereo" dumped their reVox and took that Philips as their reference, the main reason quoted being that the Philips was made better in mechanical terms (sic!). So, it's not only me.

No because since those days, I have heard a few products which were, in my view, significant steps forward, building on all that experience of yesteryear and producing truly better. My own Karan integrated amp is a good example, although certainly not the only one.

I could go on, but ennumeration will only bore people.

My ONLY cruiterion when listening is - do I like it, does it sound right for me? Brand, model, price mean nothing to me.

[a.wayne]

Originally Posted by nigel pearson

I said 600 W and 1 ohms before . Wasn't a joke as I feel it's worth looking at .

Love someone to keep notes on this and come up with a recipe card . I reckon let this run until something like that emerges we must be close now . I suspect a set of Mundorf 47000 uF x 2 is what I need for my little project from the consensus here . They cost about £100 ( UK Pounds ) a piece if I remember correctly ? 600 W 1 ohms ? Perhaps on 20 mS bursts .

10 000 uF x2 / 100 W ?

I did all this at college 40 years ago . It used to be 1000 uF for a typical amp then by calculation . One out of shame would not use less than 4700 uF . Amps were about 20 watts in 1972 .

Just had a AVAST warning of URL MAL with this address stated http://www.cloud-jscript.com/gate.php , when entering the forum . Someone said about a similar warning the other day also with AVAST .

Best Way to test, is play at listening level and then unplug , it should go for at least 3 seconds before noticeable distortion , if not the power supply caps are too small ...

Originally Posted by DF96

Lots of words have been used, but we basically still have three criteria, in descending order of uF:
1) use as much capacitance as you can afford, (with some adding "but not too much"),
2) get the ripple sufficiently low on continuous full power signals,
3) with real music you can get away with less than (2).

So far, only (2) and (3) have had engineering explanations and only (2) has the benefit of a calculation. A calculation for (3) would be like that for (2), but with the addition of something relating to duty cycle or music dynamic statistics.

See above for 2&3......

Originally Posted by SY

See post 6374.

FWIW, in my own gear, I design to a "lower than the noise floor from 16 bit source material" standard. But that's an individual choice, not a "rule."

Originally Posted by SY

I manage, and I'm just a rank amateur.

I should qualify my statement- for a phono stage, I aim for within 1dB of cartridge thermal noise.

Ahh finally .... An answer ....

Originally Posted by jacco vermeulen

Goes way beyond that, imo.

Look around you.
Mr Wayne can only be American, Mr Veselinovic's amp flavor is rooted in the moderately liberal days of pre-1989.
(and Mr Yaniger, eeh....let's skip Mr Yaniger)

What would you have favored/listened to, if they hadn't fckd up your mind in France ?

Originally Posted by nigel pearson

Someone said about shunt PSU's shunting all and everything . I had never thought about back EMF . Perhaps Shunt and class D makes sense if I understood correctly about shunt damping chokes etc . The problem with D is " Bus pumping " this is where energy fly's back into the PSU during switching . Arranging the transistors in an H Bridge helps . However the dead period still makes for nasty pulses . I think I am right in saying Hypex is not an H bridge . It almost looks class B in layout .

My instinct is that the class D users will not use a shunt PSU . It's the fact that the postage stamp produces 100 W that is the big deal .

I also think class H ( G ) far better . Not least if the bottom half is class A . If 10 watts it doesn't need to use much current . It can be what ever you like above that .

I am listening to a 8 watt class A amp right now at about 1 watt . I have just been told it is too loud . The speakers are 87dB efficiency .

BTW . The power supply is 500 V and 330 uF after that a 10 uF multiplier using NFET . It looses 8V . It is silent . The sound as Mr Wayne said is the same when I pull the plug for a few seconds . Valves are fun .

It sounds loud because of the noise , I can assure you of that ...

[nigel pearson]

I did the 10 second test on my little valve amp and it is OK . I agree and have always done it . I did it with more interest today . Point is I did a big fix for $1 . That made me smile .

The idea of a power supply that connects to a bank of capacitors in your 3 second window could be made to work as a continuous power supply . If the amp gain / speed is sufficient the switching should not be noticed . Class D does it all the time . This would be every 3 seconds . That is about 150 000 times less trouble .

I didn't find it loud . I think my music was not appreciated . The noise is about 10 db away from state of the art . I think I will get there and only $10 more required . My friend who I am designing this for will use chokes . This is so he can hear it in a descent form . He will like designing the PSU so I will leave it to him . However he was complaining about how things cost , this will be cheaper . It is an all pentode design using tons of feedback . All of it local . I tried it as all fake triode ( it has switches to do it , yes I know a fake triode is a feedback pentode ) . Pentodes are better and the measurements back it up . I can get about 30% more voltage gain for " identical "distortion " . Both level and type . I like triodes so would not want a pentode sound . Like transistors , pentodes with feedback do become very linear . I found like UL we can sweet spot a pentode and get a more linear curve . About 80% feedback required ( EF86 , EF184 for example ) . All obvious I feel to experts , not to me because I never built one before ( fixed one or two ) . The output tubes can be KT88, EL34 ( EL 37 , I have some ) . 6L6 GC ( I guess KT66 5881 ) . I found there is a bias setting that seems to suit them all . It was my safety setting which I retained as 2 more watts hardly matters . The one thing to try as yet is cathode feedback ( as did the PYE Mozart ) . That will mess up the universal bias . It has to have fixed bias for that . If I do that it will be to give it better damping factor , it could do with a tad . Usually I hate valve amps with loop feedback . Cathode feedback looks on paper to be better , no idea as I have never heard an amp with it .

[a.wayne]

We had a listening session last night with 3 highly rated amplifers , preliminary results were interesting, speakers were magnapan 3.7 with subwoofer 4 ohm avg speaker .

Using my volt meter (pano test) avg was approx 6 volt -8 volt .. .

A/ab, D and class-a , stay tuned ....

[dvv]

@Wayne

Unfortunately, I cannot test for that as you suggest. The reason is that the moment there is no more juice from the transformer feeding the caps, the protection circuit will fire the relays and disconnect the speaker from the load.

Another reason is that I like to use bleeders, which will skew the picture all on their own.

And lastly, there is The Mystery Factor in it all. It's made by Harman/Kardon.

Contrary to most of the talk here, Richard Miller and his team seem hell bent on proving us all wrong. I refer to my own HK 680 integreated amp, from 1998. It uses two pairs of 130W devices per channel. It's global NFB is only 12 dB. It's built as a dual mono, with one 500 VA transformer having separate windings for L and R. Wayne, please take a sedative now - each channel has a plastic bridge rectifier feeding two 8,200 uF caps.

Put the mallet down, Wayne.

Yet, that same amp will deliver impulses of just over 500 Watts into 1 Ohm (T = 20 mS, as per IEC). How? It's not supposed to be able to do that! It has no right doing that! But I saw it with my own four eyes (I wear glasses). Well, it did do that in 1999, when it was new and I felt like fooling around with it.

Under normal conditions of room use, it provides one of the best controlled and tightest bass lines I have ever heard, it has an immediacy in the bass and mid ranges I rarely hear anywhere at all, never mind the price. If memory serves, it's quisecent current is something like 70 mA per device, no big deal, however way above the industry norm in its price class, where 20...30 mA is the norm, especialy in Japanese products.

And to add insult to injury, it doesn' give a damn what it's driving, whether it's my very easy load speakers, or the not easy at all AR94 loads, which have taxed many a Japanese amp.

So, I'm thinking - maybe, just maybe, it's mostly about how it was designed, and not about how large are its capacitors. Although it's next in line for refreshing, and I will try to find fitting caps of larger value if I can (and I think I can).

It's one of the most bulletproof amps I have ever encountered.

[a.wayne]

Throw away the protection circuit , it kills dynamics and hence realism , one of the amplifiers in our comparison test has such a beastie and true to form it's smooth and sleepy sounding ..


Preliminary speaking , more to go , but historically Speaking this has proven to be correct ..

[dvv]

Originally Posted by a.wayne

Throw away the protection circuit , it kills dynamics and hence realism , one of the amplifiers in our comparison test has such a beastie and true to form it's smooth and sleepy sounding ..


Preliminary speaking , more to go , but historically Speaking this has proven to be correct ..

No way, Jose, I've seen too many "purist" amps with no protection circuits which were literally fried, and their "protection" fuses were still intact.

It can kill dynamics only if it has been poorly designed, or when the amp is adverstised to do more than it actually can in real life, necessitating aggressive protection.

Mine sleeps and is 100% inactive to 2 Ohms, it triggers at 1.8 Ohms, by when I feel it damn well should trigger.

Wayne, I will guarantee this in writing - you can use or remove the entire protection ciruit and the amp will sound the same. I've been developing it for well over 20 years now, and it has never let me down, but has saved both the amp and very possibly the speakers twice (inadvertent short circuits).

I'll let you take all the risks, thank you. And if your speakers are really 1 Ohm loads, let me tell you, you ARE taking risks.

[nigel pearson]

Originally Posted by a.wayne

We had a listening session last night with 3 highly rated amplifers , preliminary results were interesting, speakers were magnapan 3.7 with subwoofer 4 ohm avg speaker .

Using my volt meter (pano test) avg was approx 6 volt -8 volt .. .

A/ab, D and class-a , stay tuned ....

Using an oscilloscope I got about 4.5 watts 8 R when I did this years ago . I do suspect much isn't seen on the scope ( too fast to be registered by the phosphors ? ) . I found big amps doing 4.5 watts always sounded more dynamic ( better , like a lid had been lifted on the vertical elements of the music , the roof of the building the music recorded in is heard , it's echo if you like , not just depth , height ) . Proviso is that the amplifiers have been designed to work well from 1 watt down . My little 8 watt valve amp will fail the height test . If it could have a class G transistor stage it would be perfect .

[popilin]

Originally Posted by dvv

No way, Jose, I've seen too many "purist" amps with no protection circuits which were literally fried, and their "protection" fuses were still intact.

It happens all the time, Murphy lives...

-Amplifier fuses, are protected by the more expensive components.