Why would you get hearing damage from using a speaker amp if you are listening at the same volume level as you would from a headphone amp? I assume there's enough play on the dial on the speaker amp to get the right volume.
115 dB will cause hearing damage - as per OSHA and CCOHS guidelines and data - there is nothing at all that prevents use of something like the PM6004 (and I was going to suggest the PM8004 myself, but they're both good).
Linky:
http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=standards&p_id=9735
http://www.ccohs.ca/oshanswers/phys_agents/noise_auditory.html
None of the above is meant to be harsh/malicious - I think my post was simply misunderstood.
115dB sounds like what I'd consider a normal "way too loud" peak volume for any speaker/headphone if you crank the volume all the way to the top.
It's enough to damage your hearing PDQ. Dolby specifies peaks (note PEAKS) should be around 105 dB on the topside, assuming 85 dB is your "average" - I think that's too high for all day use, so I'd knock another 10 dB off the top. Anyone who wants to listen to triple digit SPLs is nuts.
Of course, who cranks the volume all the way to the top? :blink: It sounds just about right ot keep the knob somewhere near the 12:00 sweet spot. Beyond that is when some amplifiers are more prone to drive into distortion depending on amp design. I.E. I'm not sure on that particular amp at what point you cross the +0.0dB threshold from the preamp and start overdriving the poweramp.
No, not really.
On my Denon AVR for example I think that +0.0dB threshold is somewhere around 70% and is the max recommended setting.
If it's been designed in the last 3-4 years and has Audyssey, 0.0 dB actually floats relative to the calibration. If it's older than that (say, ~2000) 0 dB represents an uncalibrated reference level. If it's much older (say, 1995), 0 dB is probably full open, and generally there is no gain to be had beyond it. Digital gain is always nasty, but it only exists on digital preamps - on a conventional receiver/amplifier (like the Yamaha IA I have upstairs) you can run it all the way up to 11 with no problems.
Beyond that you're overdriving the poweramp and could cause distortion or clipping.
No, not really. The signal and load are what determine this. For example if I feed a signal at -50 dB into an IA and run it up to 10, it doesn't matter - it won't clip. I can also push it into clipping with the volume on the lowest setting by driving the input stage too hot. Distortion rises as power output increases, which is determined by the load relative to the output voltage (which is what you're controlling with the volume dial).
So you want the max rating to be well in advance of the average knob position
Not really. The knob position means nothing in terms of output power, it just reflects attenuation and on consumer gear is arbitrary and non-referenced. But basically all you're doing is adjusting output V, and that will translate into output power relative to the load and so on. Half on the dial doesn't mean you're getting half of the available power.
I also think there may be some important variables (I'm not sure what ones but I get the feeling there are some) not being factored into your "by the book" numbers. By your numbers, which look right, sound like they would blow transducers.
Variables such as what? Yes, you could absolutely blow the transducers up with this amplifier - I'm not aware of any headphone that can take a ~10W input and live to tell about it.
However I noticed grokit pointing out some info from Fang regarding the "HE-Adapter" (safety capacitor box for HE-6, sold seperately, for speaker taps which nobody seems to like.) Apparently according to Fang, you don't even need the capacitor protection for them when under 70wpc to 90wpc (the number apparently changed a few times.) That's in the link that was posted above for the "what amps" thread.
The HE-Adapter is not a capacitor, at least not if I'm understanding their publications correctly. There is no "safety cap" that you could use here either - it's a series of resistors (you can build the thing yourself in an afternoon) to drop voltage and current. If you want to protect the cans you'd want PPTCs and fuses among other things - a really cheap (and very effective) implementation of this is used by Bose for their speakers, and I believe it was originally sourced from Tyco (who makes said PPTCs), involving an automotive lightbulb and a reasonably high value PPTC. It protects the tweeters (which have the least power handling) from overloading - that's what the "active speaker protection" they talk about is. I'm not aware of anyone else who does this though; shame.
Obvously worrying about your ears is a different matter, but it makes me wonder if there's another factor, namely that speaker amps aren't designed to drive 53ohm loads, and thus loose efficiency in horrible ways when driving HE-6, meaning you're not really getting that 6800mw going in. That's one possible theory anyway. Point is, Fang's numbers seem a lot more power hungry than the straight calculations would suggest which implies a hidden variable that throws off how the numbers really work.
They're inefficient inasmuch as they're loading a higher resistance, but it's all dictated by Ohm's Law. I'm not sure what magical hidden variables you're worrying about - are we to believe that you disagree with all published specs, measurements, Ohm's Law, etc in relation to this set-up? Or what? (I'm confused).
And there are people running these on much more powerful amps than 45mw, though it may be merely coincidence that really high end quality amps happen to also be really powerful amps. I would suspect that the closer you get to that 70wpc threshold that marks the lowest floor of where you can actually blow a transducer
45W to 70W is an inconsequential jump, it's less than 3 dB of gain (which means it's not something you will hear and it's not worth figuring how much gain it actually represents) - both can blow apart any headphone I'm aware of.
I do suspect it has more to do with quality of amplification than overall power though in terms of how well it works, same as always.
To an extent, yes. You want an amplifier with good channel matching, a low noise floor, etc - screw any of those up and it's not fun.
HD650, K702, HE-400 all have the volume knob of the 6W Lyr down at 7:00 - 9:00 with my Squeezebox locked at 100%. Sounds great!
So the question is, 6W into what? And then how hot is your source, and what's Lyr's sensitivity? And then what's Znom of the load, and so on, and then you can figure out how much power it's actually giving up. Dollar says it's under 10 mW.
If grokit is right, it's nowhere near the need for the HE-Adapter box. Supposedly that info comes from Fang. Though personally I wouldn't tempt fate with something much bigger. And if the volume is down that box is kind of pointless short of an amp malfunction. Lyr is WAY more powerful than nearly all headphones other than HE-6 (for which it doesn't seem to be seen as enough power for), and more than capable of blowing them, but it works just fine with even the sensitive Denons so long as the volume is down. (Denons pick up a lot of noise from it though. Different issue.)
Quite honestly, you could plug them into an RMX5050 if you wanted to, and it'd work fine, as long as you could adequately attenuate the signal down (because 2Vrms on that will get you enough power to travel through time). The overall peak output of the amplifier in a given condition isn't really that relevant beyond figuring your target output goals. I think the PM6004 is a good match for the cans you've picked, as it allows you enough DNR to take your ears apart (and a 70W amp would get you nothing over that), and I like Marantz gear in general.
I think obob is just pointing out that, by the numbers, 45wpc is overkill for HE-6 based on max volume. But I don't think that takes into account other factors. Supposedly Lyr gets more than loud enough, but has a hard time driving the low end despite that planars should be linear in impedance. Maybe not in current though? That's a big diaphragm and some very big magnets.Ironically Fang's amp for them doesn't get much love either...
What do you mean "not in current" - ??? Current is dictated by Ohm's Law and helps to figure power. It's not arbitrary or independent. The user gets to adjust voltage, the load gets to set Z (as impedance aka complex resistance), the source gets to set freq, and that will give you (through Ohm's Law) a given power demand which the amplifier has to be able to deliver as a combination of Vrms output and current delivery; if it can't do one or the other it has a problem. I'm not sure how to address the complaints over the "low end" - are these actually validated, or just subjective claims made after whomever purchased something shinier and more expensive and "compared" (in a non-controlled manner) the two? It's hard to say what's going on without more information.
None of the above is meant to attack, just to inform (including you informing me, because I'm confused by some of your statements).
