[tomb]

Quote:

Originally Posted by evilking /img/forum/go_quote.gif Absolute ignorance!

Man, you guys are tough!

The PCI standard started with 5V and went on to lower it with the later standard to 3.3V. If a sound card is supplying more than that, then it's using a buck-boost circuit and those have their own particular problems with noise and trash in the audio frequencies.

Quote:

Since when have PCIe cards run on 5 volts? Go look it up. Somehow the STX runs on 12 volts, maybe it's magic!

Yeah, slight of hand with the voltage - ever scoped one? I haven't, but there's a reason high-fidelity goes with linear-regulation most often and stays away from such things.

Quote:

And those calculations give RMS voltage not peak! So the 4.38volts required for 115dB (lets pretend we have actual tin ears to withstand this volume) is actually 6.194v peak, which is definitely achievable with a modern soundcard running on 12v. EK

I made that qualification and stated that it was only an estimate, but maybe it was some more magic?

EDIT: OK, I'll claim ignorance on PCIe - I thought that was reserved for video. If not, I suppose it's possible you have a true 12V supply - is that in the PCIe standard? I haven't found anything to document it, yet.

OK - busted on the PCIe - it does appear the PCIe standard supplies more wattage through a 12V connection. OK, you got me on that one. How many PCIe sound cards do you think people are running now? I just built a PC using the latest components last year and there was only one PCIe slot on my Intel motherboard (for the graphics card). I can't imagine that they're very ubiquitous yet.

 

[CrackBerry9000]

Ignorance is thinking a sound card at one to three hundred dollars will compete with a good amp and a competent source. An HD800 or 650 or even a 701 will always make the differences obvious. People who think other wise are just fooling themselves.

Here is good advice for everyone. When using a sound card or a portable then use headphones designed for that. If you want inefficent reference headphones then plan on buying an amp and source worthy of your headphones. If you do use a portable or sound card with your 701 or 650 then don't give people advice because you are just doing the community a huge diservice. It is possible to like your equipment and not spread bad advice at the same time.

 

[CrackBerry9000]

Mods please ditch the dupe

 

[Lavcat]

Quote:

Originally Posted by chintimin /img/forum/go_quote.gif Also, people don't buy sound cards for their amps, they buy them for their SQ and features, which don't change the fact that whatever sound coming out of them quite likely has no ****ing POWER behind it.

Speak for yourself. I bought my present soundcard for its headphone amp.

 

[lwells]

Quote:

Originally Posted by Lavcat /img/forum/go_quote.gif Speak for yourself. I bought my present soundcard for its headphone amp.

HT OMEGA?

 

[Lavcat]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif When I first entered this hobby, I started investigating the best high-end, widely available headphone at the time. My research seemed to keep bringing up the Sennheiser HD580 and then the HD600. Trouble is, those headphones had an impedance (300ohms) that far exceeded other widely-available "hi-fi" headphones available at the time - Koss, Sony, etc. The higher impedance meant that they weren't being fed with optimal amplification when used with portable CD and tape players, due to the voltage limitations. (No one was interested in sound cards at the time.) That led Chu Moy to build the first CMoy. Soon after, Apheared built a CMoy and put it in a mint tin, and the rest is history. Unfortunately, this same voltage limitation is part of what started this thread and causes most people in this thread to doubt the capability of sound cards directly feeding high-end headphones, such as Sennheisers. Let's look at a few numbers ... Here's a typical set of sound pressure values for a baseline: Normal speaking voice: 65-70 dB Orchestral climax: 105 dB Live Rock music: 120 dB+ Pain Threshold: 130 dB Jet aircraft: 140-180 dB Now, if we look at the HD580/HD600, it has an efficiency of 97dB at 1mW, along with a maximum sound pressure capability of 116dB (HeadWize - Technical Paper: Understanding Headphone Power Requirements by Dennis Bohn). If we're talking about peaks - not just steady-state listening levels, and the difference between listening levels and peaks are part of what define "high-fidelity", then we'd want an amplifier with the capability to utilize that peak in the Sennheiser headphone of 116dB. The reference above seems to indicate that falls just between an orchestral climax and a live rock concert, so it's not really a stretch to want to have that 116dB available - for peaks. Just figuring for those values, using Ohm's Law and the Power relationship, we have P = (V^2)/R. Or, to find the voltage needed, V = SQRT(P x R). We start with 97dB and 1mW. Every 3dB increase is going to double the needed power. So, 100dB needs 2mW, 103dB needs 4mW, 106dB needs 8mW and 109dB needs 16mW. Let's just stop there - barely perceived above the volume level of an orchestral climax. (Note that it may still not be as great a level as a single cymbal crash transient.) The voltage needed at 109dB is SQRT(0.016 x 300), or 2.19V. Since music is reproduced in alternating voltages (sine wave), the complete voltage swing needed is +or- 2.19, or 4.38V. Note that the typical power supply for a PC is only 5V, assuming no losses. Every opamp needs a base-loaded voltage, so the sound card will probably need at least 1 or 2 volts more than the 4.38V, so the sound card's ability is already impacted. However, if we want to utilize near full capability of the headphone, we need 64mW at 115dB! Using the equations again, that results in +or- 4.38V, or a total swing of 8.76V! This is physically impossible for a sound card to provide! (A CMoy can easily manage it if using 2 x 9V batteries, though.) An amplifier must be able to supply this voltage, even for split-second, transient peaks or clipping/distortion and accompanying degradation in sound quality will occur. Of course, the same situation existed in the old days with portable CD and tape players, where voltage supplies were often limited to 2 x 1.5V AA or AAA batteries, or at best - a 4.5V AC-DC adapter. Hence, Chu Moy's CMoy. One might say why would such a high-listening level be needed? Again, one of the primary ways we define "high-fidelity" is the ability to produce a wide difference between sound levels - iow, "dynamic range." Even with the prevalent sound studio producer-compressed music that many of us listen to, a 30dB swing or more is fairly common , at least with transients. Listening at very low levels, you may be able to produce this dynamic range with a Sennheiser connected to a sound card, but you're likely to miss most of the music, too - since the Fletcher-Munson curves for the human ear have the most effect at low levels. Current ability in amplifiers follows a similar logic, but it's a bit harder to define as easily as voltage was done above. EDIT: This is just a simple rough estimate. Typically, RMS voltages are used to calculate power, meaning the voltage peaks must be higher than the values used above. Strictly speaking, the average power is corrected by a factor using the cosine of the angular frequency, or something similar - I'm sure you can all poke holes in the logic above, but maybe it illustrates the physical limitations of sound cards and fits in with the general theme of this thread.

Your post is giving misleading information. I've never built a soundcard but I have helped design PCI cards, one of which had over a hundred volt supply. The soundcard I presently use has +10v/-10v rails, according to the manufacturer's literature (and, no, I have not measured it). The rated power output is "up to" 100 mW. I don't like the "up to" language either, but I can reach a reasonable listening level from my Denons -- in a box, sealed, three feet away. And that's not with the volume maxed.

Granted your low sensitivity phones may not get quite as loud. But probably loud enough for most folks. I have 300 ohm Sennheisers too.

 

[Lavcat]

Quote:

Originally Posted by lwells /img/forum/go_quote.gif HT OMEGA?

No, Auzentech HomeTheater.

 

[regal]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif Nothing was further from the truth. It was intended to demonstrate the levels of amplification required if someone is truly wishing to emulate a live listening experience with a top-tier headphone, and to demonstrate that a simple soundcard cannot begin to reproduce the detail and transients that such a headphone can reproduce. One of the fundamentals of matching speakers to amplifiers is to match their power handling capability. You think that's unsafe because it implies that everyone is going to listen at 90-120db 8hrs a day, 5 days a week? Of course not - I wouldn't assume that of you, but you do of me.

Thats cool Tomb, just please consider the audience here, there are people who don't understand the implications of listening to headphones too loud, I think we have to be careful how we describe technical stuff like this so it is well understood. I work in a factory where a lot of people lose their hearing after 8 hrs a day for 20 years in 90dB environments because they refused to wear hearing protection. We have to keep Head-fi's good reputation as far as hearing health.

 

[evilking]

Forget all of that, does anyone really listen to music with peaks set at 115dB? It's not that I'm above high volume listening, but it's impossible for me, even with the most dynamic of my classical collection. It doesn't matter how short the peak is, they might as well be bombs going off in my ears!

EK

 

[majkel]

Quote:

Originally Posted by evilking /img/forum/go_quote.gif Forget all of that, does anyone really listen to music with peaks set at 115dB?

Whenever you take a well recorded classical CD, there is minimum or no dynamic compression applied, that's why you set it much louder than discs with pop music. Then comes fortissimo or strong, left side of the keyboard piano accords and the peaks reach near the full scale of the digital format. Dou you decrease volume right then or just listen to the rest of the concert at hardly audible level? I can tell you clipping sounds nasty in those loud moments.

 

[evilking]

Quote:

Originally Posted by majkel /img/forum/go_quote.gif Whenever you take a well recorded classical CD, there is minimum or no dynamic compression applied, that's why you set it much louder than discs with pop music. Then comes fortissimo or strong, left side of the keyboard piano accords and the peaks reach near the full scale of the digital format.

I've never measured any of the performances I've been to, but at home/friends 110+db seems much louder (tried all the way upto 120db). Maybe it's poor memory or room acoustics or something.

Quote:

Originally Posted by majkel /img/forum/go_quote.gif Dou you decrease volume right then or just listen to the rest of the concert at hardly audible level? I can tell you clipping sounds nasty in those loud moments.

That's not what I meant...

EK

 

[tomb]

Quote:

Originally Posted by Lavcat /img/forum/go_quote.gif Your post is giving misleading information. I've never built a soundcard but I have helped design PCI cards, one of which had over a hundred volt supply. The soundcard I presently use has +10v/-10v rails, according to the manufacturer's literature (and, no, I have not measured it). The rated power output is "up to" 100 mW. I don't like the "up to" language either, but I can reach a reasonable listening level from my Denons -- in a box, sealed, three feet away. And that's not with the volume maxed.

See my later posts. I'm not familiar with every single kind of sound card out there - I'll admit that up front. There are always exceptions to every rule, too, of course! However, 100V seems unbelievable unless you had a separate connector to the AC mains, or some sort of onboard transformer, AC/buck-boost circuit. At the very least, it would seem deficient in current ability in that scenario. Even in the case with +or- 10V rails, there has to be some sort of buck-boost voltage booster in the circuit, IMHO. These are very tough to tame to the standards of linear-regulated power supplies for headphone amps, where the ripple is sometimes down to the single digits in microvolts. I think Dr. Xin was the only one able to do it well on a regular basis with his very tiny portable amps.

Quote:

Granted your low sensitivity phones may not get quite as loud. But probably loud enough for most folks. I have 300 ohm Sennheisers too.

I don't disagree with this, but likely there will be entire sections of music not even heard. You won't even know what you're missing. Again, that's sort of the point of this whole thread and one my earlier post was trying to support.

 

[tomb]

Look please, everyone. The discussions about high-level dB's are misleading and I shouldn't have used them in that context. Regal is also right that it was probably too technical a discussion (and invalid in some contexts because of my attempt to combine estimation with real numbers).

All that I really meant to prove is that the reserves needed (and provided) by a quality headphone amp far exceed that capable of portable players and (most?) soundcards.

A somewhat perceptible increase in sound needs a doubling in power - that's 3dB. If we were to all agree that at least 30dB's exist in modern, compressed, pop recordings, then you'd need an amplifer that needs to respond with at least 1024X power than it did under the quietest listening levels. Let's just assume you set that amplifier to mid-way in that 30dB range - whatever the ulitmate loudness is ... you'd still need 32X power to meet those peaks without clipping (lack of voltage) or subduing (lack of current) that signal. Many of us do not believe that the typical soundcard or portable player even has the physical design to provide that kind of leverage - but top-tier headphones can respond to it, if driven sufficiently.

Where was it in this section or the amp section just recently - someone asked why headphone amps have volumes that have to be adjusted so low on the dial? Part of it is high gain, but not all - the amp has to have the reserves needed to respond to the above.

Maybe it will cause less trouble to think of it in those terms.

 

[scompton]

Quote:

Originally Posted by evilking /img/forum/go_quote.gif I've never measured any of the performances I've been to, but at home/friends 110+db seems much louder (tried all the way upto 120db). Maybe it's poor memory or room acoustics or something.

When I saw Mahler's 2nd preformed by the NSO, I'd bet that the crescendo in the last movement was 120dB. It was near pain levels for me.

 

[specto]

So am I seriously missing out on something with my grado sr325's with a cmoybb? They sound simply amazing to me.