There is nothing to say, the amp simply doesn't measures very well, nothing else.I am not sure what to say with the measurement I am seeing now.
i never said the keithley was on the same level as the audio-precision. What it does do is measure past 400vrms with an input impedance that
is electrostatic amplifier friendly. But if you really want to try and get .0000x numbers, then active high voltage fet probes or other similar items
are necessary. If you are adventuresome, then some of the victoreeen high voltage glass vacuum resistors work as input attenuators. I could post
pictures of these. Not sure where they can be purchased new anymore. Anything not vacuum glass enclosed is subject to arc-over and thats a fatal mistake. these things
https://resistorresisti.com/rx-4
i have measured many stax amps before and regardless of age they all measure better than .01% thd at 1khz at 100vrms. All of the stax amps except for the srm-001 and srm600 are fully dc coupled and when you add a low enough output resistance to ground you throw the entire amp out of balance and then all sorts of bad happens.
The koss does indeed measure much better. Reason is the open loop gain approaches 90db and the front end opamp uses 30db of that gain to reduce the distortion to low levels. And also the fact that its push pull. But the power supply kicks out at about 10 watts total power dissipation.
schematics have been posted elsewhere.
the ap technical note is 100% correct, other than its missing all the safety parts to prevent the ap from blowing up. Because at 1kv peak to peak at 20khz its real easy to generate a plasma. and plasmas have the ability to knock you ass across the room with relative ease.
Is the SRM-313 actually horrible? Granted, it is nowhere near state of the art but as a SRM-313 / SR-303 owner I am more bothered by the response of the phones. Someone already noted the infamous "shout" that can be seen in practically every Stax Lambda measurement graph.I'd like to see some modern Stax amps too. I was considering getting a Stax headphone in the near future but not with those horrible energizers lol.
Next 20 years : direct interface , civilan autonomous robots , havesting resorces from space , first humans on mars. Just to name a few things i expect to happen.
Nah worst case is solar micro nova. With our weakened magnetic field. Back to the Stone ageBest case- worst case is stagnation. Pandemic plus lazyitis and fear in the first world. Pandemic, fear and resource shortages and resulting war in the 2nd and 3rd worlds
Nah worst case is solar micro nova. With our weakened magnetic field. Back to the Stone age
If you are referring to the tube amps, I would hold my breath. The current numbers do not hold water from a basic scientific point of view. A trivial circuit analysis is quite clear on this point. The output stages are being run way outside of their design parameters when loaded by 100kΩ. Vigorous hand-waving not withstanding.A friend of mine has this and always say this is the reference of a headphone. I am not sure what to say with the measurement I am seeing now. I don't want to break his heart.
Been waiting for this kind of information for a long time, and we get four measurements in one!! Many thanks Amir
I sure wonder about the entry-level Stax SRM-252S and "mid" range SRM-353X now! Hope you get hands on them some day.
Oh and since you measured the iFi iDSD already, perhaps the iFi iESL some day
..... The oft-repeated audiophile 'wisdom' that the E/90X is the limiting factor for the ESP/95X and you need to spend hundreds to thousands of dollars on a Stax amp for the headphones to 'achieve their full potential' is evidently just another audiphool myth.
??? I call this hand-waving:If you are referring to the tube amps, I would hold my breath. The current numbers do not hold water from a basic scientific point of view. A trivial circuit analysis is quite clear on this point. The output stages are being run way outside of their design parameters when loaded by 100kΩ. Vigorous hand-waving not withstanding.
So, the 006t tube amp will have its wings noticeably clipped running into 100kΩ. Probably has a hundred or so volts stripped from its output swing.
Not sure about the 007t. But what maybe worse, the load line of the tubes in both amps will be shifted driving the lower impedance, possibly enough to make a real difference to operating conditions and distortion levels. There isn't room for a great deal of forward gain to allow feedback to reign this in, so I do suspect that the load is probably making life hard for the tube amps. The defined gain of at least the 006t is 100. I don't see a huge amount of forward voltage gain in the circuit, so feedback looks limited.
For reference, Amir has made comparative measurements before. Just FR though:Easy way out is to measure the headphones with different amps. The total distortion is what matters.
Yes.You mean distortion versus frequency?
I wouldn't put "better" and Audio-gd in the same sentence based on testing I have done. They are distortion factories:There are a number of highly linear ZERO feedback amplifiers. Audio-gd, Ayre, D'agostino and Bakkon are just a few of the better ones.
I don't know about that:There are a number of highly linear ZERO feedback amplifiers. Audio-gd, Ayre,