No need to duck
Join Our Community Subscribe to Paul's PostsWe trust that when we buy a house the doorways are tall enough for us not to have to duck. And for most of us, it’s not a problem. But, imagine if you were 7 feet tall. You’d be concerned with headroom (it’s not called headroom for nothin’).
Headroom is an elusive measure for us. We know we like having room to spare. We also know that getting to close to the limits of any piece of equipment in our stereo chain can be bad.
When Darren Myers designed the Stellar Phono, he built in headroom. Lots of it. Stellar Phono can output 20 volts rms, which is a ridiculous amount of headroom given few preamp/amp combination can take at their inputs more than 2 volts (10X less than Stellar can output).
And yet, Stellar Phono has one of the most effortless presentations I have ever heard in the 45 years I have been involved with turntables and vinyl reproduction. It’s likely no coincidence that having ten times more output capability than is needed has a direct relationship to Stellar Phono’s effortless output.
Or take the upcoming Stellar M1200 monoblock power amplifier. 1200 watts and a vacuum tube input stage without feedback that can swing huge numbers of volts—far more than needed by a magnitude. The M1200 can deliver more output than any speaker system ever needs. Yet, it too shares that same effortless quality of music as does Stellar Phono.
It’s all about headroom. The more you have the greater the ease and effortless of music regardless of load.
Some call it overkill. Others just recognize the benefits of never getting close to the edges.
But, whatever you call it, you can’t have too much of it.
I would guess that the Stellar Phono has lots of ‘headroom’ so that for its normal output range the transistors are operating in their most linear region. A 10x normal voltage swing would not be much use unless the amp, particularly its input stage, could cope with it,
Ah the ‘magnitude’, that elusive unit of measurement.
I guess that’s what the ‘M’ stands for in front of the ‘1200’.
I can just hear the sales pitch,”…& when you’re not listening to music & can take it into the garage & do some of those light welding jobs that have been piling up in there…” 🙂
“Light welding jobs”, thanks for my first laugh of the day. Since I’m about to be off to physical therapy it’s certainly appreciated. I always thought an order of magnitude is a factor of ten. Overkill in an audio system for certain, still I agree with Paul. You can never have too much headroom and I consider double what you need to be the bare minimum.
An order of magnitude = x10
Ok, OHT, good to know 🙂
In the 70’s I would occasionally use one of the PSUs for my disco amps to perform micro-welding on jewellery. It worked very well.
It may stand for mono Fat.
I’m pretty sure that you are correct, rwwear 😉
I definitely ran into the concept of headroom about 30 years ago when we visited a mall in Hong Kong and I felt like I had to duck every tine I approached a ceiling mounted sprinkler head. I’m 5’11”. My 5’1 wife wasn’t bothered at all.
My worst case of headroom was at the Victoria & Albert Hotel in Manchester. It’s next to the Granada TV studios and all the rooms are themed. Mine was The Onedin Line, a1970s programme about old ships so I got a ceiling full of beams with 5 foot of clearance. A very painful experience.
Designing gain settings on phono amps is important.
– I had a bespoke unit with variable MC gain added, but fixed MM gain, for the simple reason that the less MC gain you need the better.
– My digital Devialet phono stage sets the MC gain automatically (it has a cartridge database), can be set manually, and the MM is set manually (it can be done from the remote whilst the system is playing). The maximum is 15mV, but I had it set at 3mV. Having 5x headroom makes no difference – the main thing is to get a similar loudness compared to other inputs at the same volume setting.
– I have an external MM/MC phono stage, which has 12 gain settings between 45.4dB and 61.4dB. Same loudness approach applies, except you have to turn things off when adjusting.
I’m not convinced about the need for headroom on Class D amplifiers as, certainly with mine, you can run it at full power without distortion. It can deliver very high peak current. To the contrary, the DSP system that is specific to the speakers (again, from an online database) prevents the amplifier from overloading the speakers and blowing them up.
So it may be about headroom for some classes of amplification, but probably less so for Class D systems that are active or have DSP.
I would have thought any component should be designed to perform best in the range that it is designed to be used in. If that means components are only used to 20% of their limit, then fine, but if unused capacity is built in at extra cost, I don’t see the point of that.
Steven, I have to disagree on class D amps and headroom. I have listened a lot to Hypex nCore 400 and Hypex nCore 1200 amplifiers in my system. Both amps have the same gain, and I certainly do not run out of power (wattage) when running the NC-400 based amp. Still, the NC-1200 based amp sounds better in virtually all aspects of performance: more open, wider soundstage, increased separation between individual elements in the soundstage, even better representation of low level details (the most perplexing aspect of this performance delta to my mind). While these amps do differ a little in their input stages, the designer feels the input stage on the NC-400 is actually better (fully discrete input stage on the NC-400 vs. an IC based design on the NC-1200). These differences confound me a bit, but looking at the distortion curves do show that both of these amps have rising distortion with power output (as do virtually all amps).
My takeaway is that one can never have too much power available! My speakers are two-way, with two 7″ mid woofers running in parallel, so they do seem to like a fair amount of current availability, so that may be a factor.
I am looking forward to hearing the new Stellar Monos, they might be a good match for my set up.
It really depends how you do design these amplifiers. I use a hybrid amplifier, Class A voltage and Class D current, and before that I used hybrids with Class A voltage and Class B current. Both are patented designs, but have been around for decades. I heard an amplifier last weekend (Trilogy 995R) that is a hybrid operating either Class A to 40w or A/B to 200w. The speakers were sensitive (92dB Wilson Sasha DAW) so were easily driven by the 40w Class A and the sound was spectacular.
This reminds me of the old adage, Wear extra clothes, You can always take them of you cant put them on ! There is no replacement for displacement ! Id rather have it and not need it than need it and not have it !
Ok Im sure you get the picture
I remember this from an old article from an audio interview !
“Once, Bob Carver visited a famous sound researcher who was attempting to recreate the “snip” of an ordinary pair of scissors. He used no less than TWENTY-FOUR 200-watt amplifiers for playback, yet when viewed on an oscilloscope it was apparent that the top of that instantaneous transient was being distorted. Believe it or not, he needed more power! It was evident that real-world sound occurs very quickly and requires far more power than ANY current amplifier could produce”
Human hearing is so indoctrinated with what we know to be real its not easy to fool the ear brain combo when listening to reproduced music !
While headroom is important – What I look for is the rated power to double for every 1/2 the load impedance (8-4-2- and hopefully 1), (300W 600W 1200W 2400W) and for it to be fully stable at those values.
This is not necessarily an indicator of sound quality, and I don’t think headroom alone is either. It is rather an indication of current delivery capabilities of an amp, and it’s ability to drive difficult loads. If you don’t have a difficult load then things just ‘idle’ along. If the load gets difficult you want something to keep that load in check.
I own a few of those grey monsters ! Your post re affirms my earlier one ! As for sound quality that’s always subjective as speakers are what your hearing in theory !
C.A.P.
We’ve been on the same ‘page’ for the last few posts. I agree the speakers are what moves air (and us). The amps move the air movers.
Like you said better to have the oomph and control available then wish you had it…
When we know how important headroom is and that it affects sound quality so much, why then is it called headroom? Is it only because we’re not really aware about the reason for the SQ benefits because we just connect power output capability with the theoretically much lower need on the input side?
It also seems to me, putting in enough headroom is one of the least understood but most easily to implement measures…and therefore meanwhile practiced by quite every manufacturer from a certain price level on. I guess there are other design features with more reason to be proud of them…but headroom and the size of transformers is so dammed easily visible and understandable for the customer, that it will always dominate much more sophisticated design details to be mentioned in the brochures.
More headroom is always good. Especially when visiting medieval castles in Scotland or England. For those over 5 foot six a Cap is recommended. For those 6 foot and over the helmet is mandatory.
No doubt for an amplifier more headroom is always good. But if you have high-efficiency speakers, 1200 W seems excessive overkill. For my +100 dB/watt speakers I believe the law of diminishing returns is not past but broken.
Without a doubt the new Stellar 1200 watt amp will be, stellar. But I wonder if we’re about to see the start of a power war with amplifier manufactures. With class D amplification, high power and low distortion (when done right) is now economical.
The 1960s was the era of the muscle cars. Will the 2020s be the era of the muscle amps?
Once a very long time ago I used to think this way. Then I became an engineer. When you spend other peoples’ money you often have to explain not only what you are doing but why and what other choices you have and why the one you selected is the best and most cost effective one. Building something 10 times, 100 times, 1,000 times what is needed must have strong justification or it will be unacceptable to those who must approve the expenditure. Rightsizing is a term invented to express that part of the engineering art that looks at current needs, possible or likely future needs, and uses sound judgment borne from experience to make intelligent choices. We don’t want solutions that are inadequate or marginal but we also don’t want to throw money away. Is a 1200 watt amplifier justified for powering a pair of Klipschorns? Not any more than a 3 watt tube amplifier is justified for powering a pair of Magnepan LRSs. One solution is modular design that is configured for later upgrades when changes are needed. This is done to avoid obsolescence of the original expenditure.
What makes these oversized electronic units sound superior (assuming they do?) I’m going to take a guess. It’s the output impedance being low which is partly the result of a superior power supply. Circuit topology also matters. An preamplifier or DAC with a class AB output stage will have a far lower output impedance than an topology with an emitter follower or cathode follower output stage which is what is often traditionally used. ICs usually can’t handle much current either. Discrete transistors would be preferable IMO. This difference probably won’t matter when the input impedance of a tube amplifier is 100 Kohms or more but it can make a substantial audible difference when a solid state amplifier input is only 5 or 10 Kohms. A high capacitance or high inductance connecting cable only makes matters worse by rolling off the high end.
Why stop at 1200 watts? Dick Burwin has a home sound system that is 20,000 watts.
http://www.burwenaudio.com/Sound_System.html
Will a loudspeaker/amplifier combination that can produce 126 db peak loudness without distortion in your home sound any more like a symphony orchestra than one that can only produce 106 db maximum loudness, 1/100 the power? I don’t think so. Less than 1% of all symphonic music produces sound in the audience louder than 106 db (I don’t know of any that reach even that level.) The real differences between live and recorded sound are qualitative, not quantitative.
Oversizing equipment has major disadvantages and pitfalls. This is true for both electrical and mechanical systems but maybe not for structural systems. In one project for a large corporation a data center had been decommissioned, the equipment removed and the space was repurposed for document storage. The data center AC system was left as it was. Before long it was realized that not only was it very cold in that space but the documents were starting to grow mold. The oversized AC system achieved the desired temperature which controls the on/off cycle long before it removed much humidity from the air. An incompetent consulting firm came up with the brilliant idea to put terminal reheats in the HVAC air discharge system. A monster heating system to fight a monster AC system. Talk about inefficiency and sheer incompetence.
I’ve encountered the following problem more than once and thankfully I was never responsible for it. When inadequate power was available from an electrical substation the engineer replaced the transformers with larger ones. These types of transformers have impedances rated in percent and are associated with their KVA (power) rating. The larger transformers could deliver much more current in a short circuit than the original transformers but the next downstream equipment, a circuit over-current interrupter was not rated to withstand that much short circuit current. The result of a short circuit on the load side of the next protective device could have resulted in an explosion rather than a circuit breaker trip. For a 2500 KVA transformer at 480 volts that’s 2.5 million watts in something the size of a shoe box. It will last for a few milliseconds after which it will heat to about 30,000 degrees and explode.
What do you do to protect your expensive speakers from being overloaded and destroyed by an overpowered amplifier that can deliver far more power than the speakers can withstand?
What if you replaced the engine in your car with one that could produce 800 horsepower so that you could go faster? Would you melt the tires? Would you burn out the transmission. This is one more reason to think about intelligent system design rather than just assembling components that you like.
Further to your argument against overpower, the message I get from reading so many amplifier reviews is that the lower power amplifiers in a manufacturer’s line typically sound sweeter with more clarity in the mid-range. There seems to be an optimal matching of amplifier to speaker that achieves a sweet spot and too much power loses that harmony. I’ve lived by that rule in audio and it has served me well.
NOT true at all. Lower power amps are just that. Lower power less current and less headroom. Tube power is different from transistor power. J fet ,Mosfet, are just switching devices just like a tube is . .. Its the impedence and distortion. What many associate as the tube glow and warmth is actually micro distortion in a good way !
There was a time when lowest distortion was the war to be fought. Funny a few of these men now making amps are not so keen on it and actually embrace a tiny warmth from it !
Its not so much of how many watts you have but how clean that first watt is. and that HEADROOM behind it if needed !
Hence my earlier, facetious comment about using the M1200 for some light welding duties 🙂
Headroom is good, excessive gain is a pain.
Meanwhile several years ago my (shorter) wife bought me a baseball cap with hard hat insert fitted.
It has saved me so many bumps and bleeds I can highly recommend for those of us who are tall and/or clumsy and/or living in a place designed for shorter folks 🙂
Just read Michael Fremer’s review of the Stellar Phono….. Incredibly positive review saying that it basically holds it’s own with units costing 10 to 20 times as much.
Congratulations are in order!