Robert Harley's TAS Editorial

[FrantzM]

microstrip (note the correct orthography for the handle no shorthand.no 'strip or anything)

Solidity of images is not the province of SET... I heard the effect from various amplifers and SET are not superior in this regard. I do believe however that when not taxed they have an uncannily realistic reproduction of the Human Voice... The midrange is their forte with Headphones and with speakers that does not tax them. In the case of my experience with the SET headphones amplifier, OTL by the way the thing that struck the most was the robustness of the rest of the spectrum. I ultimately went toward the Luxman Headphones amplifier but I must say I sometimes (too foten?) regret that move. I could have been very happy with the Woo... In my experience I have that "holography" from several amplifers some of them SS (Burmester,Dartzeel. Plinius, Goldmund, Gryphon, Spectral, Bryston 28B monoblock EDGE stereo and monos, LAMM SS and many others I am forgetting as for tubes the list is as long and includes SET, OTL Triodes and Pentodes so ....) so I don't think SET image any better than other amplifiers ... And preemptively it is not an analog thing .. Steve has a CD of Boz Scags that does the trick in a way that will have well mannered people cussing... .... if the system is up to it ...

One more thing do you really believe Headroom needs to be defined???

 

[Steve Williams]

Frantz

did I make you a copy of that album

 

[fas42]

Ahhh, headroom ...

To bring forth that accursed car analogy: you can either buy a sports "monster" capable of going 200mph, just to be confident that it will travel competently at 80mph -- you never, ever travel anywhere near that maximum speed, but the engineers had to get some things sorted out reasonably well to reach that level of speed. So it should be good for the far more sedate pace ...

Or, you use normal parts, make sure that it fully capable of travelling soundly at 85mph, and tops out at 88mph maximum speed. Again, it is extremely at its ease, maintains that desired 80mph comfortably.

One method is extremely expensive, uses a great deal of resources; the other is very efficient, represents excellent ROI. It's all about choices ...

Frank

 

[JackD201]

Micro, is Hartley some kind of Freudian slip as in Nina.......?

Just foolin' around my friend

Nelson Pass has a very good white paper on single ended, ZNFB circuits that applies even if this Editorial is about tubes.

 

[microstrip]

microstrip (note the correct orthography for the handle no shorthand.no 'strip or anything)

Solidity of images is not the province of SET... I heard the effect from various amplifers and SET are not superior in this regard. I do believe however that when not taxed they have an uncannily realistic reproduction of the Human Voice... The midrange is their forte with Headphones and with speakers that does not tax them. In the case of my experience with the SET headphones amplifier, OTL by the way the thing that struck the most was the robustness of the rest of the spectrum. I ultimately went toward the Luxman Headphones amplifier but I must say I sometimes (too foten?) regret that move. I could have been very happy with the Woo... In my experience I have that "holography" from several amplifers some of them SS (Burmester,Dartzeel. Plinius, Goldmund, Gryphon, Spectral, Bryston 28B monoblock EDGE stereo and monos, LAMM SS and many others I am forgetting as for tubes the list is as long and includes SET, OTL Triodes and Pentodes so ....) so I don't think SET image any better than other amplifiers ... And preemptively it is not an analog thing .. Steve has a CD of Boz Scags that does the trick in a way that will have well mannered people cussing... .... if the system is up to it ...

One more thing do you really believe Headroom needs to be defined???

FrantzM,

I can agree on much you write, but how does it relate with the TAS 223 editorial and my comments about it?

 

[Phelonious Ponk]

Perhaps, just perhaps we're measuring the wrong things?

Perhaps. Can anyone tell me what Hartley measured?

Tim

 

[Phelonious Ponk]

And how do you objectively define headroom? AFAIK, lack of headroom just results in distortion (lots of it, to be more exact).

Personal definition, not an objective one -- enough power that the amplifiers barely need to awaken to sufficiently power the drivers through their average load, enough power to drive them through any transient peak your music collection is likely to deliver without excess effort. Hard to define technically, I'm sure (I won't even try, personally), as there are variables involved, but you know it when you hear it. And it is only lots of distortion when there is lots of clipping. The small, common headroom issues that cause strain during transients compress and constrain more than they obviously distort. The results are loss of clarity, dynamics and transient response resulting in a subtle loss of all those many things audiophiles describe with other words -- sound stage, micro dynamics, air, musicality, PRaT. But the most striking thing that a clean system with more than sufficient power sounds like is a complete lack of strain. You lose much of that "hifi" sound, and get a more easy, natural, effortless presentation of the music, without any special sauce covering problems. My ears, MHO. Now, I'm going to stop before I start sounding like you guys.

Tim

 

[Phelonious Ponk]

Ahhh, headroom ...

To bring forth that accursed car analogy: you can either buy a sports "monster" capable of going 200mph, just to be confident that it will travel competently at 80mph -- you never, ever travel anywhere near that maximum speed, but the engineers had to get some things sorted out reasonably well to reach that level of speed. So it should be good for the far more sedate pace ...

Or, you use normal parts, make sure that it fully capable of travelling soundly at 85mph, and tops out at 88mph maximum speed. Again, it is extremely at its ease, maintains that desired 80mph comfortably.

One method is extremely expensive, uses a great deal of resources; the other is very efficient, represents excellent ROI. It's all about choices ...

Frank

Wrong car analogy. It could be a light weight sports car or a heavy luxury sedan, but it has no transmission It has sufficient power, and lots of torque, in reserve, because the designers know that it will not just be asked to cruise at 80 across flat land, never needing more than an extra few % in reserve required to get it up to 85. It will, instead, be traveling across a much more challenging landscape, and asked to suddenly climb mountains with no "low gear" to shift into and nothing but raw power to keep it from slowing down.

Tim

 

[microstrip]

Perhaps. Can anyone tell me what Hartley measured?

Tim

Tim,

For this editorial nothing at all.
Fantastic how people can write comments without reading the piece.

 

[Phelonious Ponk]

Tim,

For this editorial nothing at all.
Fantastic how people can write comments without reading the piece.

I've commented on the "objectivist" nature of people who believe in cables but not blind testing, my general impression of the objectivist nature of TAS and my own personal opnion regarding the source of the magic of SET, but I haven't commented on this piece at all.

Tim

 

[fas42]

Wrong car analogy. It could be a light weight sports car or a heavy luxury sedan, but it has no transmission It has sufficient power, and lots of torque, in reserve, because the designers know that it will not just be asked to cruise at 80 across flat land, never needing more than an extra few % in reserve required to get it up to 85. It will, instead, be traveling across a much more challenging landscape, and asked to suddenly climb mountains with no "low gear" to shift into and nothing but raw power to keep it from slowing down.

Tim

I would beg to differ. You make the excellent point that it is the difference between speed and torque that we are really worried about: speed meaning the voltage swing, and torque being the level of current delivery that the power supply is capable of without sagging or glitching. And the key factor is the torque, delivery of clean current. To put it another way, a 30 watt amp may have excellent "torque", capable of delivering its maximum power in a pristine manner all day, yet a 600 watt unit may start to stress very rapidly if asked to maintain such power levels in real loads. A simple guide is seeing how the power delivery is maintained as the impedance drops: a 30W into 8 ohms, 60W in 4, 120 in 2 component is quite superior in what counts than a 600W in 8, 750W in 4, 900W in 2 performance. If they were the figures shown to me, I would take 30W unit, that's the device that has usable, engineered "headroom".

Frank

 

[rbbert]

...my general impression of the objectivist nature of TAS...
Tim

You mean "none", I assume? You might sometimes see a simple 2-D line graph of a speaker's frequency response measured in-room (i.e., too many variables and not enough specificity to be useful).

 

[Phelonious Ponk]

I would beg to differ. You make the excellent point that it is the difference between speed and torque that we are really worried about: speed meaning the voltage swing, and torque being the level of current delivery that the power supply is capable of without sagging or glitching. And the key factor is the torque, delivery of clean current. To put it another way, a 30 watt amp may have excellent "torque", capable of delivering its maximum power in a pristine manner all day, yet a 600 watt unit may start to stress very rapidly if asked to maintain such power levels in real loads. A simple guide is seeing how the power delivery is maintained as the impedance drops: a 30W into 8 ohms, 60W in 4, 120 in 2 component is quite superior in what counts than a 600W in 8, 750W in 4, 900W in 2 performance. If they were the figures shown to me, I would take 30W unit, that's the device that has usable, engineered "headroom".

Frank

Did I say headroom = watts? Don't recall saying that.
Tim

 

[fas42]

Did I say headroom = watts? Don't recall saying that.
Tim

Tim, you've said power many times, and that's watts, a measure of the power deliverable. Power, in an amp = Voltage swing x Current delivery. Voltage swing, going back to the car analogy, is how fast you can make the wheels spin under no load, lifting the driving wheels off the ground, which in an amp is a function of the voltage rails, whether 30V, 60V, or 90V, etc. But torque is what counts when the wheels hit the road, when you flatten the accelerator can the car maintain the same speed on the flat, and then going up steeper and steeper hills.

The 30W amp performing as I mentioned in the previous post is equivalent to a vehicle being able to maintain its maximum speed on 3 different steepnesses of hill, this is true headroom -- the amp will always perform with a sense of ease. The key selling point for Krells, for example, the power doubling as you double the load. And that is only possible if the power supply is capable of delivering what is required at any point of time. The truth is, most amplifier power supplies are extremely marginal, they collapse, or sag with severe glitching, extremely rapidly if they are required to keep delivering high levels of power.

EDIT: A simple way of expressing the above is to say headroom as you think of it = ability to double the power when doubling the load, irrespective of what the measured maximum power number actually is.

Frank

 

[jap]

Fantastic how people can write comments without reading the piece.

+1.

This seems to be his MO.

 

[fas42]

"Headroom" can also be seen as a measure of merit of an amp, and just thinking about it, an interesting way of grading such would be to determine the maximum power achieved continuously into a load of 1 ohm. Maximum power is usually determined for a distortion reading of 1%, and have continuous meaning that the distortion level is stable at that level for 10 minutes. Now, some amps will struggle to get anything happening at this load, delivering less than 1 watt perhaps, and that in fact will be a good measure of their subjective worth. I suspect that creating a sorted table of the measured figures will align very nicely with how many audio people would rank the amplifiers in terms of headroom grunt ...

As a variation, use a distortion figure of 0.1% rather than 1% to create another version of that list, which would probably rank the items more in terms of quality rather than grunt; could be an interesting exercise.

Frank

 

[Soundproof]

The member who started this thread should have included extracts from or the entire editorial, in order to let as many as possible participate in a discussion. Without that, the thread becomes as silly as it's become.

Editorials are quotable, in that they are considered an expression of opinion by the publication, and as such not under restriction by copyright laws.

 

[Phelonious Ponk]

+1.

This seems to be his MO.

Currently, that seems to be your MO. you evidently haven't read the post your commenting on.

Tim

 

[Phelonious Ponk]

I would beg to differ. You make the excellent point that it is the difference between speed and torque that we are really worried about: speed meaning the voltage swing, and torque being the level of current delivery that the power supply is capable of without sagging or glitching. And the key factor is the torque, delivery of clean current. To put it another way, a 30 watt amp may have excellent "torque", capable of delivering its maximum power in a pristine manner all day, yet a 600 watt unit may start to stress very rapidly if asked to maintain such power levels in real loads. A simple guide is seeing how the power delivery is maintained as the impedance drops: a 30W into 8 ohms, 60W in 4, 120 in 2 component is quite superior in what counts than a 600W in 8, 750W in 4, 900W in 2 performance. If they were the figures shown to me, I would take 30W unit, that's the device that has usable, engineered "headroom".

Frank

I'm sorry, frank, I didn't read this carefully enough the first time, and I think we're mostly in agreement, though I think you've had to describe extreme examples of 30 and 600 watt amps that rarely exist to make your point. As you know, I vi-pass the issue altogether with systems that use individual amps for purpose-designed individual drivers. Even in that methodology, though, they almost always use fairly high wattage amps.

Tim

 

[JackD201]

I noticed a funny thing about high powered SS amps into very light loads. It takes a friggin long time to get them at good operating temperature. You could leave 'em on 24/7 but suffer the electricity bill. What do ya get when running cold? Distortion. Ain't real life a blast?