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HE-500, LCD2, D5000, DT770, SR80, on a speaker amp (Emotiva mini-X A-100) Project
Oct 18, 2013 at 2:56 AM Post #1,951 of 3,819
shazb0t said:
I also hear a very slight hiss with the emotiva mini-x and HE-500. From reading this entire thread I believe they all have a small noise floor, but that the people claiming they hear nothing either don't have as sensitive hearing or have not actively listened for it at 0 volume. It does get much louder towards 2 on the dial, but with a normal dac you shouldn't need the volume that high. That's my take on it for what it's worth.
Click to expand...

Actually I am not interested in HE500 but HE-4 / HE-6 so with their ultra low sensitivity there sould be no sign of even small amount of hiss ...
 
Do you have any technical info about up to what power it stays in A class, max peak to peak voltage, distortion values at different power output ? (read somewhere about 80V p-p but don't know the source)
 
Oct 18, 2013 at 4:07 AM Post #1,952 of 3,819
magicman said:
  Actually I am not interested in HE500 but HE-4 / HE-6 so with their ultra low sensitivity there sould be no sign of even small amount of hiss ...
 
Do you have any technical info about up to what power it stays in A class, max peak to peak voltage, distortion values at different power output ? (read somewhere about 80V p-p but don't know the source)
Click to expand...


I suggest you use resistors on the output section of your amp. It's how I got rid of the very obvious hiss of my amp without affecting SQ.
 
Oct 18, 2013 at 4:50 AM Post #1,953 of 3,819
Oct 18, 2013 at 8:56 AM Post #1,954 of 3,819
Could anyone with an A-100 comment on this question?  I just noticed for the first time last night.
 
Since I received the amp, I have mostly left it on to let it burn-in.  I turned it off last night and then back on about 30 minutes later.  I noticed that after I immediately turned it on and turned the volume pot, there was a very distinctive noise, like a 'whooshing' type of sound any time the volume pot was moved - up or down.  If it was stationary, that wasn't there.
 
I checked and it did it again this morning after being off overnight.
 
However, after about a minute or so of being on, this went away.
 
Does the amp just need a bit of time to warm up (capacitors get charged?) before turning the volume?  Or could some of the caps be failing?
 
I just picked this up so I'm getting concerned there may be a hardware issue with it.  Anyone with an A-100 that can test that out and let me know would be great!
 
Thanks
 
Oct 18, 2013 at 8:58 AM Post #1,956 of 3,819
daemonsire said:
  Could anyone with an A-100 comment on this question?  I just noticed for the first time last night.
 
Since I received the amp, I have mostly left it on to let it burn-in.  I turned it off last night and then back on about 30 minutes later.  I noticed that after I immediately turned it on and turned the volume pot, there was a very distinctive noise, like a 'whooshing' type of sound any time the volume pot was moved - up or down.  If it was stationary, that wasn't there.
 
I checked and it did it again this morning after being off overnight.
 
However, after about a minute or so of being on, this went away.
 
Does the amp just need a bit of time to warm up (capacitors get charged?) before turning the volume?  Or could some of the caps be failing?
 
I just picked this up so I'm getting concerned there may be a hardware issue with it.  Anyone with an A-100 that can test that out and let me know would be great!
 
Thanks
Click to expand...

 
 
Take it back and get another one.  That's what I would do.
 
Oct 18, 2013 at 11:27 AM Post #1,958 of 3,819
daemonsire said:
  Could anyone with an A-100 comment on this question?  I just noticed for the first time last night.
 
Since I received the amp, I have mostly left it on to let it burn-in.  I turned it off last night and then back on about 30 minutes later.  I noticed that after I immediately turned it on and turned the volume pot, there was a very distinctive noise, like a 'whooshing' type of sound any time the volume pot was moved - up or down.  If it was stationary, that wasn't there.
 
I checked and it did it again this morning after being off overnight.
 
However, after about a minute or so of being on, this went away.
 
Does the amp just need a bit of time to warm up (capacitors get charged?) before turning the volume?  Or could some of the caps be failing?
 
I just picked this up so I'm getting concerned there may be a hardware issue with it.  Anyone with an A-100 that can test that out and let me know would be great!
 
Thanks
Click to expand...

It's likely due to the quality of the potentiometer itself or potentially a faulty pot.  It's not easy to swap in a new/better one either unfortunately due to the design, but I'd recommend contacting Emotiva support regarding the issue.
 
Oct 18, 2013 at 11:48 AM Post #1,959 of 3,819
daemonsire said:
  Could anyone with an A-100 comment on this question?  I just noticed for the first time last night.
 
Since I received the amp, I have mostly left it on to let it burn-in.  I turned it off last night and then back on about 30 minutes later.  I noticed that after I immediately turned it on and turned the volume pot, there was a very distinctive noise, like a 'whooshing' type of sound any time the volume pot was moved - up or down.  If it was stationary, that wasn't there.
 
I checked and it did it again this morning after being off overnight.
 
However, after about a minute or so of being on, this went away.
 
Does the amp just need a bit of time to warm up (capacitors get charged?) before turning the volume?  Or could some of the caps be failing?
 
I just picked this up so I'm getting concerned there may be a hardware issue with it.  Anyone with an A-100 that can test that out and let me know would be great!
 
Thanks
Click to expand...

 
Thanks sounds way odd to me. Better contact Emotiva and see if you can get a replacement.
 
Oct 18, 2013 at 3:42 PM Post #1,960 of 3,819
ohhgourami said:
 
I suggest you use resistors on the output section of your amp. It's how I got rid of the very obvious hiss of my amp without affecting SQ.
Click to expand...

I am sure there will be no hiss with HE4/HE6 using a-100
 
your Krell is just overkill, too much power, too much gain, nothing strange you can hear some hiss
 
from some level of output power there are more cons than pros and amp should be carefully picked when connecting headphones to speaker amp directly, even these ultra low sensitive
 
a-100 has still nice power (especially for HE4), but great S/N ratio, very low distortion and many other factors (that's why I chose it + it's brand new unit, safe design)
 
Oct 18, 2013 at 6:54 PM Post #1,962 of 3,819
Talked with Emotiva Support and they believe it is normal.  They said that they usually let their gear warm up for a minute or so.  The fact that this disappears after being turned on for a minute and doesn't happen during normal operation, they didn't seem to think it was an issue.
 
Still curious if other people's A-100's do this.  Pretty easy to check...have the unit off (for a period of time), have the HE500's connected, turn the unit on and as soon as you hear the "click" that the muting really has disengaged, move the volume pot.  Do you hear anything?  It is a constant noise so the level of volume doesn't affect it.
 
Thanks
 
Oct 18, 2013 at 8:09 PM Post #1,963 of 3,819
Why is it you can't get speaker amps with switchable gain or something?
 
Oct 18, 2013 at 8:21 PM Post #1,964 of 3,819
davidsh said:
  Why is it you can't get speaker amps with switchable gain or something?
Click to expand...

 
Two reasons:
 
1) Impedance mismatch - With headphones, this tends to happen the most. Speakers and speaker amps are usually more in harmony
 
2) Pre-amp - Usually for stereo or even home theatre speaker rigs, there is typically a pre-amp involved somewhere in the chain, rather than a DAC line out to power amp. Emotiva is just a power amp.
 
Oct 19, 2013 at 12:50 AM Post #1,965 of 3,819
yeah, actually putting some resistors on the amp's input is simply lowering its gain ...
 
I will let you know if my brand new unit acts the same (it will take some time to get to POLAND) but for me this is not normal behaviour, but don't know the implementation of the amp to tell
 
DaemonSire - this is why I never buy used stuff (especially when it's cheap like a-100), too many people have no idea how to use stuff and what is not good/safety for their equipment, but that's just me ... there is always a chance to get broken unit directly from the manufacturer but this is small chance ...
 
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