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The Predator, Portable Headphone Amp/USB DAC Combo
Member of the Trade Sponsored Threads ForumThis is where Members of the Trade will pay for time-limited, topic-specific discussion threads for the purpose of advertising.
You say the gain is set at 11 in high. An iPods line out is 1vRMS, which is 2.8vpp full scale(volts peak to peak, according to Vinnie on various threads). Wouldn't you need ATLEAST 32 volts to have a gain of 11 on an iPod so you don't have some serious clipping or distortion when the volume is cranked really high? ESPECIALLY on high load cans like 600 ohm DT880s?
Gain was something I was mulling over when I was looking at some DIY designs to power 250ohm Darths, and there was a design that utilized a gain of 11, but it had a powercord/dedicated PSU. When I saw gain of 11, I thought "predator" and then thought I'de ask if this is the case with the Predator, since I can't see 34+ volts coming out of that LiOn battery. Can you shed some light? This is partly the reason I'm not in bed yet, lol.
__________________ Nate
Music -> Amp -> Headphones
"I want a nightclub on my head." :basshead:
mr_baseball: I guess times have changed and Head-fiers are getting laid like champs now. (Except I seriously doubt that's the case given all the anime and computer related threads around here..)
You say the gain is set at 11 in high. An iPods line out is 1vRMS, which is 2.8vpp full scale(volts peak to peak, according to Vinnie on various threads). Wouldn't you need ATLEAST 32 volts to have a gain of 11 on an iPod so you don't have some serious clipping or distortion when the volume is cranked really high? ESPECIALLY on high load cans like 600 ohm DT880s?
Gain was something I was mulling over when I was looking at some DIY designs to power 250ohm Darths, and there was a design that utilized a gain of 11, but it had a powercord/dedicated PSU. When I saw gain of 11, I thought "predator" and then thought I'de ask if this is the case with the Predator, since I can't see 34+ volts coming out of that LiOn battery. Can you shed some light? This is partly the reason I'm not in bed yet, lol.
Still doesn't answer much, or maybe I'm missing something.
*edit* over 1000 views since I asked the question and still no answer from Ray (or anybody else?)???
__________________ Nate
Music -> Amp -> Headphones
"I want a nightclub on my head." :basshead:
mr_baseball: I guess times have changed and Head-fiers are getting laid like champs now. (Except I seriously doubt that's the case given all the anime and computer related threads around here..)
Oicdn. I think you have a good question there. I am trying to follow. I have a nagging recollection of seeing a reference to Mac line-in voltage as 1v peak-to-peak, and elsewhere to line-out voltage as the same. I did find references for Vinnie's figures of 1 vrms and 0.75 vrms for the Classic. No luck on the Apple site.
If the voltage were peak-to-peak rather than rms, would the gain of 11 seem more feasible from the battery?
Wouldn't make a difference how it's measure, the values are still the same, 2.8v peak-to-peak, or 1vRMS.
The gain of 11 seems a little ambitious or optimistic for such a power supply (LiOn batteries that small).. If the batteries are infact over 32 or so volts (custom battery pack), I can see there not being a problem with suffieient headroom. But if there isn't 32 or so volts, the closer you get to maxing out the volume in high gain, the closer you get to clipping and distortion with insufficient power behind it.
Which means if you have a high impedance load and you need to crank up the volume pot to about 50% or maxed, there's gonna be clipping and distortion...right?
__________________ Nate
Music -> Amp -> Headphones
"I want a nightclub on my head." :basshead:
mr_baseball: I guess times have changed and Head-fiers are getting laid like champs now. (Except I seriously doubt that's the case given all the anime and computer related threads around here..)
Moderator: Headphoneus Supremus: The first to organize an International Head-Fi Meet (2006)
Isn't the gain just a compensation for headphone impedance loads? I wouldn't put it on 11 for a pair of IEMs and I wouldn't put it on low for a pair of 600's. Why does it matter what the Ipod puts out?
It just to have more adjustability on the volume switch for different kinds of cans.
Remember, the amp is being powered by the recharchable built in battery, and only the DAC is being powered by the USB port. The Pico works the same way.
__________________
**********************************
-My house was built for lovin'...not a theater of war.
-Realize it's harder to find your own voice, then to follow one, already in the air.
~~~><///'>~~~><///'>~~~><///'> ~~~
Music is my recreational drug...I need a dose, everyday!
The input voltage is directly related to what's output, i.e GAIN over source.
Meaning, if the voltage is 1vRMS, and you have a gain of 11, that's 11x1, or if you convert it 1vrms to a sine wave 2.8vpp, that would be 11 x 2.8vpp = 31.1vpp.
Taking into account headroom, you'll want around ATLEAST 32 volts (most opamps lose .4 to .8 volts) to be able to drive it up to full volume without distortion.
32 volts. I doubt that battery is 32 volts (I could however be wrong). So, mathematically speaking, that amp will only reach a certain point on the volume pot on high gain before it starts clipping and distorting SEVERELY.
I wish Ray could clear this up for me. I keep going over it and it just seems impossible for that to be able to run a gain of 11 without it going wacky when turned up, either for loud volumes, or you're just driving high ohm cans.
__________________ Nate
Music -> Amp -> Headphones
"I want a nightclub on my head." :basshead:
mr_baseball: I guess times have changed and Head-fiers are getting laid like champs now. (Except I seriously doubt that's the case given all the anime and computer related threads around here..)
Moderator: Headphoneus Supremus: The first to organize an International Head-Fi Meet (2006)
It's been 24 years since I've graduated in electrical/computer engineering, so I can't confirm your calculations. However, in Florida we had the HD6XX and the K701's playing at ear-shattering levels and there was no distortion to be had.
Unless you are truly planning on adding a Predator or Pico to your stable, I don't think that you should loose too much sleep over the math.
Even then, you can always return any of our members amps without a restocking fee. Our MOT's are not Best Buy or Circuit City.
You should never buy an amp or headphones based on other member's opinions. Another option is that to get to a meet and try them with your own ears when they are in full production.
End of speculation.
__________________
**********************************
-My house was built for lovin'...not a theater of war.
-Realize it's harder to find your own voice, then to follow one, already in the air.
~~~><///'>~~~><///'>~~~><///'> ~~~
Music is my recreational drug...I need a dose, everyday!
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