[Yevgen Chupak]

With the jumpers installed and leaving my headphones plugged in with it on with no music playing can it damage the headphones with the amount of power going through them?

No

 

[Yevgen Chupak]

The auto-detect mode on the A-100 turns on when the audio coming into the amp exceeds a certain level...
And it remains on as long as the average level remains above a certain level.
If the average level falls below the threshold it will turn off.

So, if what you're listening to is too quiet, for too long, the amp will turn off.
If this happens, then simply set the amp to "always on", and it won't happen.
The A-100 doesn't really draw enough power to worry about when it's idling.
(The fact that this only happens with certain sources seems to prove that there's nothing wrong with the amp.)

Gotcha tnx. So what i need is to keep my volume on that specific lvlv and autodetect should work just fine.

 

[KeithEmo]

When nothing is playing the power going to your headphones is zero and it's not going to bother anything.

HOWEVER, under most circumstances, that is a REALLY BAD HABIT to get into if you have relatively low impedance headphones.......
All you need to do is forget they're plugged in, and turn the volume up too high, and you can easily smoke your headphones in a permanent sort of way.

At a very minimum you should get in the habit of turning the volume on the amp all the way down when you end your listening sessions.

With the jumpers installed and leaving my headphones plugged in with it on with no music playing can it damage the headphones with the amount of power going through them?

 

[Rchandra]

With the jumpers installed how much power is going to my headphones at noon on the dial?

 

[IBJamon]

With the jumpers installed how much power is going to my headphones at noon on the dial?

That number totally depends on the headphones and what impedance they have. According to the specs page:

Power Output (headphone output; direct drive mode)
(requires internal jumper; USE WITH CAUTION):
8 Ohms: 50 watts / channel
33 Ohms: 12 watts / channel
47 Ohms: 8.5 watts / channel
150 Ohms: 2.6 watts / channel
300 Ohms: 1.3 watts / channel
600 Ohms: 0.6 watts / channel

That is maximum power, and the knobs are logarithmic. But I would Never Ever use the headphones with them turned up half way as a starting point. You always start with them very low, and slowly increase as needed. Otherwise you are just asking for blown headphones.

 

[Rchandra]

That number totally depends on the headphones and what impedance they have. According to the specs page:

Power Output (headphone output; direct drive mode)
(requires internal jumper; USE WITH CAUTION):
8 Ohms: 50 watts / channel
33 Ohms: 12 watts / channel
47 Ohms: 8.5 watts / channel
150 Ohms: 2.6 watts / channel
300 Ohms: 1.3 watts / channel
600 Ohms: 0.6 watts / channel

That is maximum power, and the knobs are logarithmic. But I would Never Ever use the headphones with them turned up half way as a starting point. You always start with them very low, and slowly increase as needed. Otherwise you are just asking for blown headphones.

I'm using a sony Z1R..I normally go to almost noon at times but wonder if it's damaging my driver's lol

 

[IBJamon]

I'm using a sony Z1R..I normally go to almost noon at times but wonder if it's damaging my driver's lol

If you ears are not blown out, it's probably fine. All I can say is that if you switch sources and the other one is substantially louder than another (say a quiet song vs. a loud one or a youtube vs. a game) you may be in for a rude awakening. But I wouldn't worry about it if your ears are not on fire.

 

[IBJamon]

I just looked up those headphones. Very impressive (and expensive!!!). You can damage those, but I'm sure they can take quite the beating. Enjoy!

 

[Rchandra]

I may have messed something up on them with the loud volumes lol something is a bit off on the left side lol but that could be my brain more then anything else

 

[HiFiRebel]

Can I connect speakers like these to A-100?

 

[IBJamon]

Can I connect speakers like these to A-100?

Absolutely. A few extra watts is nothing to worry about. Unless you plan to run then full blast for hours on end, they should work perfectly.

 

[HiFiRebel]

Absolutely. A few extra watts is nothing to worry about. Unless you plan to run then full blast for hours on end, they should work perfectly.

Thank you

 

[meowKittieh]

Hi All!

Earlier today I lurked through the last 40 pages of this thread because I'm really interested in the A-100. After that, I pulled the trigger and picked one of these up on Amazon.

Like many other posters I was struck by Mr. Zeos's enthusiasm and it seemed to do him well with the Argons, which I've ordered. I think I need to stop watching his channel. Aside from Z-reviews, one of the things that pushed me over the edge on buying this was seeing the designer chip in on this thread. In my limited experience it's pretty rare to see THE hardware designer come in and offer up info on the design and insights on how to use it. So cool!

Anyway, I figured I'd share some of my thoughts on the amp. Mainly about the noise, as to me this is a defining factor on how useful this is as a headphone amp. It sort of makes sense to me why there could be noise with jumpers placed. AND, since I've had two fingers of Arberlour, I'll type out how I see things... please excuse egregious grammatical or mathematical errors or if I'm being too obvious or pedantic...

The SNR on this thing is pretty darn good at 110dB (at full scale output... sqrt(50Wrms*8Ohms)=20Vrms). However, if you're just driving some 16 ohm IEMs your true "full scale" may very well be less than 1Vrms (50-ish mW). Since you're making use of only 5% of the actual ~20V full scale (or at most 20*log10(1/20) = -26dB) your relative SNR will be closer to 110dB - 26dB = 84dB. The T50RPs, being beasts at 3W / 50ohm, would use up more like 12V. Assuming you REALLY enjoy listening to them at MAX volume, you'd be making use of 60% of the amplifier headroom (only ~4.5dB down from full scale) and your relative SNR would be up to ~106dB. I think a lot of this is dependent on how YOU hear, but, loosely equating lower effective SNR to higher amounts of audible noise, you should hear more noise with more sensitive and lower resistance headphones... that is, if you hear any noise at all. This also explains why adding series resistance decreases noise as you'd be using more output voltage.

Luckily for me, the A-100 is going to be pulling double duty and its day job is going to be driving some Klipsch RP-15ms... if the hiss is audible w/my headphones, I'm still getting at least 50% of the intended use out of this thing. I will post again in a few months with my actual experiences with the A-100 when I've finally got those lovely Argons in-hand.

Ramble over. Glad to be on the forum!

 

[LHS]

Has anyone fixed the hiss issue? My jumpers are in place. There is an extremely audible hiss coming out of my LCD-X. No hiss coming from my speakers from the same source. Do I have a dud?

I've tried moving USB ports and power cables for the A100 and my audio interface.

 

[meowKittieh]

For whatever it's worth, my A-100 just arrived and I'm also getting a slight hiss. I can just barely hear it coming out of my RP-15M tweeters, sitting ~3' away. Turning off all nearby potential sources of EMI, I'm still hearing it. Also tried pulling source and output cables to no avail. I'm also getting a slight hiss my HD6XX w/o the jumper placed. Just for fun I downloaded a spectrum analyzer app for my phone. Moving it closer to and away from my tweeter, it appears the noise is broad spectrum and could indeed be the amp noise floor (vs. picking up hum from power).

@LHS You're par for the course IMO...

I'm going to use it for a few days and return if it's not to my liking. One of the perks of ordering from Amazon, I guess. At least this amp/speaker setup beats the every loving crap out of my Creative Pebble speakers.