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# The Beyerdynamic DT880 Discussion thread - Page 375

Quote:
Originally Posted by Shaffer

FWIW, my Oppo105's HP-out is rated at something like 17mw@600 Ohm and it drives my 880/600 louder than most can stand. Numbers....hard to listen to music with.

Lol here are more numbers....

my dac/amp combo has BTL outs which bump out 8 watts at 4 ohms 5 watts at 8 ohms. I currently use them to drive floorstanding speakers...klipsch rf-20 and they are as loud as I want them to be lol. RF-20s are supposedly 96 db sensitivity at 8 ohms...but hey lol it works :o which surprised me...

### Gear mentioned in this thread:

Quote:
Originally Posted by Chris J

Hmmmmm......

If DT880/600 Ohm 'phones do 96 dB SPL @ 1 milliWatt, then 10 milliWatts = 106 dB and 100 milliWatts = 116 dB.

If you listen to music with 20 dB peaks (i.e. you need 20 dB of headroom) and you listen at an average level of 96 dB SPL, then 100 mW should be enough.

yes. That is it. That was the math I was looking for.

Quote:
Originally Posted by Chris J

Because we love to "discuss" amp power,

I ran some numbers on the various impedances of DT880 to show current draw and voltage needed for various power levels.

32 Ohm Versions   (note: Innerfidelity specs the efficiency as 0.47 mW = 90 dB SPL)

1 mW = 179 mV, 5.6 mA

5 mW = 400 mV, 12.5 mA

10 mW = 565 mV, 17.6 mA

25 mW = 935 mV, 27.9 mA

100 mW = 1.79 V, 55.9 mA

250 Ohm versions   (note: Innerfidelity specs the efficiency as 0.38 mW = 90 dB SPL)

1 mW = 500 mV, 2.0 mA

5 mW = 1.12 V, 4.4 mA

10 mW = 1.58 V, 6.3 mA

25 mW = 2.5 V, 10.0 mA

100 mW = 5.0 V, 20.0 mA

600 Ohm versions   (note: Innerfidelity specs the efficiency as 0.43 mW = 90 dB SPL)

1 mW = 775 mV, 1.29 mA

5 mW = 1.73 V, 2.89 mA

10 mW = 2.45 V, 4.0 mA

25 mW = 3.87 V, 6.5 mA

100 mW = 7.74 V, 12.9 mA

Peruse the numbers.

Keep in mind you need an amp that can output 7.74 Vrms to drive a 600 Ohm DT880 to 100 milliWatts.

This usually works out to a desktop amp with a gain of approx. 14-20 dB.

Quote:
Originally Posted by knightboy140

Lol here are more numbers....

my dac/amp combo has BTL outs which bump out 8 watts at 4 ohms 5 watts at 8 ohms. I currently use them to drive floorstanding speakers...klipsch rf-20 and they are as loud as I want them to be lol. RF-20s are supposedly 96 db sensitivity at 8 ohms...but hey lol it works :o which surprised me...

Believe it or not, 96 dB SPL is bloody loud!

Quote:
Originally Posted by Chris J

Believe it or not, 96 dB SPL is bloody loud!

Heh, putting it mildly, especially when the driver is right on one's ear (for most intents and purposes).

Edited by Shaffer - 12/4/13 at 5:02pm
Quote:
Originally Posted by Chris J

Believe it or not, 96 dB SPL is bloody loud!

it is lol.

A subway train arriving at a subway station is about 100 dB SPL....

Quote:
Originally Posted by knightboy140

it is lol.
A subway train arriving at a subway station is about 100 dB SPL....

Consider, too, that doubling the physical distance from the source amounts to a ~6dB loss.
Quote:
Originally Posted by Shaffer

Quote:
Originally Posted by devhen

Your profile doesn't answer any of my questions. But that's OK, I just wanted to point out that there's a lot more to it than "my amp puts out XXXmW and its loud enough."

Actually, I pointed that out. It's not the number on the spec sheet that serves as the final determinate.
Quote:
BTW, when I say "compressed" I mean dynamic range compression, not lossy/lossless file compression.

I know what compressed means, likely better than you could possibly imagine. At the risk of sounding less than kind, the text in the profile would have answered all of your questions, if you actually understood what it said. That requires a bit more experience. No offence meant.

Edit: format

I did not mean to imply that you don't know what compression is, or to offend you in any way at all, so I'm not sure why you're using that tone.

How does your profile answer the questions? It does not say whether you listen to compressed or uncompressed music. It does not say what the gain level of the Oppo15's headphone output is. It does not say whether you use gain normalization. Those were my questions.

The rules of head-fi are very clear: be nice. The mods take it VERY seriously and will delete posts and ban members that are not kind. You don't know me and I don't know you. I don't know what the extent of your knowledge is on this stuff, nor do you know mine, so refrain from comments like "I know more than you could possibly imagine." I just don't see how that adds anything to the discussion other than being kindle to start a flame war. I did not mean to imply that you know or do not know about compression, or anything else, and I apologize if you got that impression.

Quote:

Originally Posted by knightboy140

Yes I know that....I was just saying for most purposes...

My personal take on this is audition gear before you buy....or buy gear you know you can return...

^ Great advice. You need to find out for yourself to be sure.

Quote:
Originally Posted by knightboy140

Lol here are more numbers....
my dac/amp combo has BTL outs which bump out 8 watts at 4 ohms 5 watts at 8 ohms. I currently use them to drive floorstanding speakers...klipsch rf-20 and they are as loud as I want them to be lol. RF-20s are supposedly 96 db sensitivity at 8 ohms...but hey lol it works which surprised me...

I have a pair of Klipsch, as well. Big, old, horn-loaded. I don't think they've ever used more than a few watts, if that.
Quote:
Originally Posted by devhen

^ Great advice. You need to find out for yourself to be sure.

I found that out the hard way lol

I once read that those old horn-loaded speakers were often so efficient, you could rig them up to a pocket transistor radio and get useable volume in a medium-sized room. I suppose they would have had to have been; the tube equipment in those days wasn't exactly a wattage powerhouse.

Quote:
Originally Posted by Shaffer

Consider, too, that doubling the physical distance from the source amounts to a ~6dB loss.

I see this quoted all the time.

This is in free air, free space.

SPL does not drop over distance like this in a typical listening room.

Quote:
Originally Posted by Shaffer

Quote:
Originally Posted by devhen

I did not mean to imply that you don't know what compression is, or to offend you in any way at all, so I'm not sure why you're using that tone.

How does your profile answer the questions? It does not say whether you listen to compressed or uncompressed music

It says LPs, tape, DSD/HD/FLAC files, CDs and zero MP3. It also says no EQ anywhere. How do you think lossless, uncompressed recordings are defined?

LPs, FLACs, CDs -- these can all have widely varying levels of dynamic range compression applied to them during recording which absolutely does effect how loud they play out of your system. I thought I was clear when I said I was talking about dynamic range compression, not audio file compression.

Quote:
Originally Posted by Shaffer

Quote:
It does not say what the gain level of the Oppo15's headphone output is.

Seems like you have Internet access of your own. Two clicks.

Will do. I thought you might know.

Quote:

Originally Posted by Shaffer

Quote:
It does not say whether you use gain normalization. Those were my questions.

How, exactly, can gain normalization be utilized in such a system? By what means can such a thing be achieved? I'd love to hear an answer, as an external compressor/limiter is the only real option. Kinda funny, you know.

When you listen to your FLACs, for example, is your music player applying gain normalization? Its a simple, and completely legitimate, question that does in fact apply to your system in the case of digital audio files such as FLACs.

Quote:
Originally Posted by Shaffer

Given your comments and questions, it sure seems like you have a bit to learn. Sorry, but it's the truth. If that offends you, I apologize.

Nothing we've discussed gives you reason to assume how much I know or how much I need to learn. There's a word for your assumptions despite that, its called ignorance. I'm not interested in speaking with you anymore. You obviously aren't going to show me the respect that I, and everyone here on head-fi, deserves. Bye.

Edited by devhen - 12/4/13 at 5:46pm
Quote:
Originally Posted by Chris J

I see this quoted all the time.

This is in free air, free space.

SPL does not drop over distance like this in a typical listening room.

Because, pressure having a chance to dissipate is actually more powerful than the same being contained in a defined space? Yea, that makes sense.
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