I bought the Moon... and all I got was an Eclipse.

A very, very nice CD machine indeed. I now have the right (two) glowing blue. Spacious, rythmical and dynamic with tuneful and extended base... what do you want more?

Not too foward, not too laid-back, just the right momentum to keep the music flowing in a free and natural breath&pace. A very satysfing 3D music experience.

Now the big surprise... it's incredible how close an old and cheap Marantz CD-40 can get in terms of the same music enjoyment. The big diference only being a more 2D perspective. In the end they both are true multibit machines anyway...

I have also finished the 1K's new crossovers... they're just putting out more and more Beryllium dust... which is a must.

One big disapoitment though... I did the null test to the MF A1000, and I could hear all the distortion it's producing.

Does anyone know about any amplifier with a good null test?

I heard a DIY integrated with almost perfect null test and I can't stand anything else...

It makes me think how far the industry is from that goal. We really are walking blind...

 

What's a null test

 

Good to hear you like the Eclipse. Its a cracking player!

 

I'm guessing that'd be where you subtract the output from the (suitably scaled) input to see how much distortion gets added on the way through - obviously for a perfectly transparent system you get a zero or 'null' result.

 

Ooh get you smarty pants!

Thanks for the expl all the same

 

Technobear,

The null test is the most simple and definitive way of eveluate an amplifier performance.

It serves the sole purpose of determining if the input of the amplifier is equal to its output by less the gain factor.

You can do it yourself at home if you have an old or spare amplifier. Just connect the CD player output (one channel) to the input of the amplifier being eveluated. Simultaneously connect the + signal of the same CD player output to the + input of the other (spare) amplifier. Take the + speaker output of the first amplifier (under test) and connect it to the ground (normally its chassis) of the spare amplifier. Connect the spare amplifier output channel (the same as the input) to a speaker. Turn down the volume of the amplifier being tested. All your spare amplifier is doing now is to eveluate the signal difference (distortion) between the input and the output signals of the other amplifier (under test). Because the volume in your amplifier is turned down all you can hear through the speaker is the direct output signal of the CD player. (You must set a volume point in you spare amplifier in order to be able to hear it.) As you start to increase the volume in the amplifier being tested its output signal is subtracted to the direct output signal of the CD player and you start to hear it lower. You will eventualy reach a point where the amplifier output voltage is the same as the CD player direct output which means you should hear no sound (a null) coming out of the speaker providing you have a perfect amplifier under test. Unfortunately, no comercial available amplifier (and I just know one no comercial amplifier that is able to do it) can do it, so you'll still hear a sound which is no more, no less the distortion that your amplifier is producing. The lower the sound the less the distortion.

So simple and so true...

 

I find it amazing that amplifier null tests aren't done more often. Indeed, I think it ought to be one of the standard tests done for a review. It is truly the only objective test of an amplifiers sound quality and I really can't see how anyone can argue against them. After all, if an amplifier is reproducing the input signal with gain (and nothing else) - the famous "wire with gain" then isn't that the perfect amplifier?

I have witnessed one (non-commercial) amplifier that has a null test result that is probably as close to perfect as its possible to get...and it also sounds stunning

The null test also has the attractive property that it allows you to hear, in real time, the distortion of an amplifier. The null signal of the "perfect" amp I heard had to be connected to an oscilloscope at very high resolution before the minute levels of distortion were measurable - they were totally inaudible. 99% (perhaps 100%) of commercial amps have a pretty audible (and hence pretty poor) null test.

Michael.

 

No way Michael! Forget about the null test, all that matters is what we hear and if the ear is pleased then why worry... mine is pleased even with my car stereo in a traffic jam.

And normally the ear is so pleased that we keep changing our equipment countless times... the industry must go on. Who cares about the truth, about the hi fidelity concept. Keep changing, keep buying... that's why Musical Fidelity (isn't it ironic?) is such a bless.

Take for instance Merlin's big Mac... if he ever could possible know the result of its null test what he could possible say about its glorious sound?!

We are no different from professional reviewers... and we are enjoying it and paying it, thinking we know something. We know nothing!

So, keep you ears pleased and busy... cause each time you'll be paying more for the old same lore. The show must go on!

 

It is truly the only objective test of an amplifiers sound quality and I really can't see how anyone can argue against them. After all, if an amplifier is reproducing the input signal with gain (and nothing else) - the famous "wire with gain" then isn't that the perfect amplifier?

I'd broadly agree, with the caveat that the amp under test must be driving it's intended speaker load at the time of the test. That could mean long leads to place the load speaker in another room while you listen to the 'difference'!

The point being - a static test tells you little that relates to real world performance- that's the very problem with just relying on specs. Listening to how the amp performs under load could be very, very interesting, and start to reveal where the idea of synergy comes from...

I have several amps to hand, and might just give it a go this weekend

 

I agree with you felix. That is another beauty of the null test in that it can be done with the amp driving real speakers with real cables, listening to real music, in real time.

The "perfect" amp I mentioned above was being tested in such conditions

Michael.

 

Okay you two. I'll bite. What's this 'perfect' amp you've been on about..?

reg

:Quad:

 

Don't Halcro amps have the lowest measured distortion of any amplifier on the market?

Ever heard one Michael :SLEEP: :SLEEP: :SLEEP: :SLEEP: :SLEEP:

 

It's a DIY amp built by a Portuguese friend of ours who's also an occasional visitor to this forum by the name of "Tube Dude". Contrary to what his nickname might imply, it's not a valve amp. Whilst at his place we null tested a couple of other amps he had lying around, an Audiolab 8000S and an Orelle (can't remember the model) and both had pretty dire null test results.

There's a thread about null testing with Tube Dude contributing here:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=13415

Michael.

 

But does it sound any good?

 

I have indeed heard one, and would agree with your asessment. However I've no idea in what way their distortion figures have been measured. They're almost certainly static measurements done at fixed frequencies

Again, I'd ask anyone to come up with a credible argument for why an amplifier which has a perfect (or as close to perfect as is measurable) null test, in real world conditions, driving real speakers playing real music can be anything other than perfect. If it is reproducing the input signal exactly, but with gain, then if you don't like what you're hearing the problem must lie in the input signal or the speakers.

Michael.

 

Tube Dude's amp is amongst the best I've ever heard. So, yes.

Michael.

 

Maybe because it is *driving* speakers (being driven by is perhaps more accurate...). How about null-measuring an amp (I assume power) as attached to real speakers in a real room at real volumes with real, dynamic music.

 

Not being a techy, I don't know what these mean.

Still, they do raise the question of the relevence of low levels of measurable THD in amplifiers to the enjoyment of music lovers IMO.

 

But that's what I meant . I don't really see the difference to what I said.

merlin - I'm not too familiar with how to interpret those Stereophile measurements either but they appear to be done with square wave or sine wave signals at fixed frequencies - not familiar with any music like that. Also, they refer to "simulated" speaker loads, not driving an actual speaker.

Michael.

 

That would be what a 'nulling test' implied.

Beryllium's arrangement looks highly dubious.

Paul