Emotiva A-100

[torifile]

I saw some reviews complain about hiss with their headphones with this amp. Is that a common experience?

I experienced a hiss at all volumes. Emotiva swapped it out. The new one is also hissing at all volumes. This occurs with and without the jumpers in both units. I’m thinking of returning mine.

 

[IBJamon]

So I just received it today. I am relieved to find that I do not hear any hissing! (Or at least with kids it wasn't noticeable with the background noise.) I do notice a very faint ground loop/hum, which goes away with the source disconnected and gets louder as the volume goes up, so it's not a problem with the amp. Ironically, it may be that hum that's keeping the amp from shutting off on auto...

I tested my M1060s and my Fostex T50RP Mk3s. The Pioneer SE-A1000s also sound very good. The M1060s do not need more power, but the Fostex need more without the jumper in place.

I will check out the jumper soon, though I don't know if it will be today or not. We'll see.

I've considered my idea of making a jumper switch, and I may instead make external adapters for other headphones and use them rather than plugging in directly. More to come.

 

[IBJamon]

Out of the box, these do not have enough power for my T50RP Mk3s. But unleashed? Oh wow. That's all I gotta say.

My other headphones sound incredible in beast mode, but can by used with such a tiny amount of the volume knob it's pointless. So I gotta try some other stuff.

There is a super tiny amount of hiss with the jumpers in (that the T50s don't even register) but none with the jumpers engaged. I am fortunate, I suppose.

 

[garbulky]

Out of the box, these do not have enough power for my T50RP Mk3s. But unleashed? Oh wow. That's all I gotta say.

My other headphones sound incredible in beast mode, but can by used with such a tiny amount of the volume knob it's pointless. So I gotta try some other stuff.

There is a super tiny amount of hiss with the jumpers in (that the T50s don't even register) but none with the jumpers engaged. I am fortunate, I suppose.

Hiss is tiny for me too inaudi ble during music. Reduce volume upstream and move the minix to past volume where there is no channel imbalance and is as loud as you can listen to. For me its Then control volume upstream of the amp. So in essence minix is a power amp in that mode. This way youll have more control.

 

[IBJamon]

Does anyone know why Emotiva put in a straight resistor rather than a proper voltage divider for the headphone out? 2 extra resistors is not a big cost difference, so that likely isn't it...

 

[m usicguy]

I have two of these amps.

NO hiss just pure bliss sound.

I think we all need to remember this is a small speaker amp. Emotiva is coming out with the new DC-2 and a headphone amp in march maybe april. Go over to the emo lounge and you will see they are making a dedicated heaphone amp, from what i read unless things have changed.

The A-100 is a monster for headphones but it is a "hack" for more power. Tell me of a headphone amp manufacter that makes this much power for 229 dolllars.

m usicguy

 

[IBJamon]

It's a wonderful amp, and I am tickled with it. I am just trying to make an adapter that I can use with more efficient headphones, while still having 'beast mode' available for my Fostex. Even my other planars have next to no volume play as things currently are, but I also want to keep the low output impedance, so I am thinking of making a voltage divider rather than a simple resistor as they are currently implemented.

 

[garbulky]

It's a wonderful amp, and I am tickled with it. I am just trying to make an adapter that I can use with more efficient headphones, while still having 'beast mode' available for my Fostex. Even my other planars have next to no volume play as things currently are, but I also want to keep the low output impedance, so I am thinking of making a voltage divider rather than a simple resistor as they are currently implemented.

Ask Keith at the Emotiva forums. He'll probably have some advice

 

[iamjaymo]

So I gave the jumpers another chance and what I said before about the jumpers not really adding anything wasn't entirely accurate...they do make a difference...quite a difference. I wasn't using a variable source before so I couldn't get the volume pot past where I needed to in order to avoid channel imbalance, etc.

I connected using my AGD R2R 11 in variable mode and wow! Magnificent! It's not like the tone changed but it did seem more dynamic and clearer perhaps. I can liken it to the change the Schiit Eitr had, you can definitely hear it, but it's not like you just saved the world or anything. It certainly drives my Alpha Dogs better, cleaner, and with more authority.

 

[iamjaymo]

Was looking at the Schiit Jotunheim in order to have more power and drive my Alphas via balanced but I don't think I'm going to need it now. There is no headphone amp that has more power than this little $229 beast. Pretty happy with the Emo, it's quite the value proposition.

 

[garbulky]

So I gave the jumpers another chance and what I said before about the jumpers not really adding anything wasn't entirely accurate...they do make a difference...quite a difference. I wasn't using a variable source before so I couldn't get the volume pot past where I needed to in order to avoid channel imbalance, etc.

I connected using my AGD R2R 11 in variable mode and wow! Magnificent! It's not like the tone changed but it did seem more dynamic and clearer perhaps. I can liken it to the change the Schiit Eitr had, you can definitely hear it, but it's not like you just saved the world or anything. It certainly drives my Alpha Dogs better, cleaner, and with more authority.

Yay! I knew you'd hear it! I agree about the dynamics. I think this is the mode to run with unless the headphones are way too sensitive for them

 

[iamjaymo]

Interesting tidbit, I have the volume turn up pretty high on the A-100 (about 3:00) and I don’t hear any of the reported “hiss” or any of the amp’s noise floor when no music is flowing. Dead silent.

 

[IBJamon]

So I made a few adapters, and learned a few things. First things first:

If you have inefficient planars like my T50RPs, then by all means use direct mode. It's awesome!

My more efficient headphones (M1060s, Pio SE-A1000s and of course IEMs) do hear a bit of hiss in direct mode. It's not bad, but it's there. As expected they also don't have much play on the volume dial.

So I wanted to have direct mode an easy access, so rather than make a switch like I originally planned, I decided to make some external adapters so I set bridge mode, closed it up, and got to work.

One of my adapters is an exact clone of what's inside; a simple 1/4" to 1/8" adapter with two 220 Ohm resistors soldered right to the jack terminals. I used ones just like these (except sourced locally, and they are all black):

https://smile.amazon.com/Conwork-6-35mm-Connector-Microphone-Speaker/dp/B072MCDHH4/ref=sr_1_12?ie=UTF8&qid=1519186384&sr=8-12&keywords=1/4+solder+plug

They have enough room to solder a pair of 1 or 2 watt resistors to the terminals inside.

I made another adapter based on this schematic:

https://diyaudioheaven.wordpress.com/headphones/headphone-attenuation-adapter/

For those not familiar, this is also often called an L-pad.

This choice is based on the idea that a low output impedance will sound better. My first attempt was a DIY fail (parts broke when I was done, etc.) using a box, and I tested with massive 5W resistors using the otherwise same specs as the example (33Ohm/3.3Ohm) and before I broke it (long story) it sounded quite good, though these new ones I made did not exist yet so I couldn't compare them. So for round two, I made something similar except using 18Ohm/1.8Ohm 2W resistors using the plugs above. It works, but honestly sounds a bit grainy. (EDIT: They no longer sound grainy at all. I normally don't worry about break-in, but they sound fine to me now.) I also have some 47Ohm/4.7Ohm ones that I believe might sound better. (The place I bought from didn't have 2W 33/3.3Ohm resistors available.)

You can easily customize the L-pad using the formulas I found on this page:

https://robrobinette.com/HeadphoneResistorNetworkCalculator.htm

I believe the 220Ohm approach may have better crosstalk, while the L pad approach probably works better with some impedance sensitive headphones. I like having both available, though since my 18Ohm one seems to have a short in it, I may scrap that one for now (and maybe switch it to 47Ohms later since I already have them).

For the record, the 220Ohm cable attenuates a bit less, but the top half of the dial is worthless because the amp runs out of jiuce (thanks to the crazy high resistance I suspect) whereas the L pad adapter seems to just get louder, despite having more knob room, because it's more useful throughout the power band and the amp has more power to spare since to the amp it thinks the load is much less.

Anyway, I hope that helps and some of you find what I did interesting!

 

[garbulky]

So I made a few adapters, and learned a few things. First things first:

If you have inefficient planars like my T50RPs, then by all means use direct mode. It's awesome!

My more efficient headphones (M1060s, Pio SE-A1000s and of course IEMs) do hear a bit of hiss in direct mode. It's not bad, but it's there. As expected they also don't have much play on the volume dial.

So I wanted to have direct mode an easy access, so rather than make a switch like I originally planned, I decided to make some external adapters so I set bridge mode, closed it up, and got to work.

One of my adapters is an exact clone of what's inside; a simple 1/4" to 1/8" adapter with two 220 Ohm resistors soldered right to the jack terminals. I used ones just like these (except sourced locally, and they are all black):

https://smile.amazon.com/Conwork-6-35mm-Connector-Microphone-Speaker/dp/B072MCDHH4/ref=sr_1_12?ie=UTF8&qid=1519186384&sr=8-12&keywords=1/4+solder+plug

They have enough room to solder a pair of 1 or 2 watt resistors to the terminals inside.

I made another adapter based on this schematic:

https://diyaudioheaven.wordpress.com/headphones/headphone-attenuation-adapter/

For those not familiar, this is also often called an L-pad.

This choice is based on the idea that a low output impedance will sound better. My first attempt was a DIY fail (parts broke when I was done, etc.) using a box, and I tested with massive 5W resistors using the otherwise same specs as the example (33Ohm/3.3Ohm) and before I broke it (long story) it sounded quite good, though these new ones I made did not exist yet so I couldn't compare them. So for round two, I made something similar except using 18Ohm/1.8Ohm 2W resistors using the plugs above. It works, but honestly sounds a bit grainy. I also have some 47Ohm/4.7Ohm ones that I believe would sound better. (The place I bought from didn't have 2W 33/3.3Ohm resistors available.)

You can easily customize the L-pad using the formulas I found on this page:

https://robrobinette.com/HeadphoneResistorNetworkCalculator.htm

I believe the 220Ohm approach may have better crosstalk, while the L pad approach probably works better with some impedance sensitive headphones. I like having both available, though since my 18Ohm one seems to have a short in it, I may scrap that one for now (and maybe switch it to 47Ohms later since I already have them).

For the record, the 220Ohm cable attenuates a bit less, but the top half of the dial is worthless because the amp runs out of jiuce (thanks to the crazy high resistance I suspect) whereas the L pad adapter seems to just get louder, despite having more knob room, because it's more useful throughout the power band and the amp has more power to spare since to the amp it thinks the load is much less.

Anyway, I hope that helps and some of you find what I did interesting!

Talk to "@KeithEmo" aka keithl on the emo forums. He will very likely give you useful advice. Hes an engineer there. Mention what you tried.

 

[torifile]

I’m jealous of you guys who didn’t have any hiss with the amp. I sent mine back today because the hiss was intolerable.