[rsvette12]

They were not on to begin with - put them on last night - pretty simple took about 2 minutes

Sound is better just wondering if bass would be fuller (more warmth maybe) with tube pre-amp or would it not be much different, at the moment its better with jumpers but bass can get a little muddy still - thanks Bequiet

 

[rockytopwiz]

Them good ole Tennessee boys, emotiva is seriously the best.

 

[rsvette12]

Them good ole Tennessee boys, emotiva is seriously the best.

? Me not even close - Snowville Mass here

 

[rockytopwiz]

No takers on my questions thanks


Hi Guys:

New here and just picked up a Emotiva 100 for my HD650's - Pretty impressive - I use it for my guitar interface and interested in this post about adding a tube preamp - would it be worth trying this, I do not want to mess up Emotiva or mess with Emotivas functionality as it is - if preamp makes it even better then that would be great

I am thinking of getting a Little Dot MKII - would like the III but invested enough all ready

If you feel this might be a nice edition - how would I run this configuration - right now I have guitar interface into the input of Emotiva and plug in headphones into front of Emotiva

What would be the routing if I added tube preamp ?

Also recommendations on no jumper or add jumper on HD650's why I ask is the bass is not quite there starts to break up a bit

Thanks much

Not speaking from personal experience but there is a video by Paul at psaudio on YouTube saying the best place to add a tube is in the preamp.

To do it you would go out of the dac(guitar interface)- into preamp line in-line out of the preamp into line in on the amp.

I've never done this and there are varying opinions on if it's worth doing.

 

[rsvette12]

Thanks for the info much appreciated - so the Tue would before the Emotiva thats interesting thought it would be the other way around - searching found nothing on this subject

That post by Lasher caught my attention and I would not give up my Emotiva but those tube amps are pretty cool looking and if there was some benefit to it I would give it a go

 

[rsvette12]

Just found this - very interesting may be something I might wan to try as I am using with my guitar - and looks like it may be a great match ohms wise with Emotiva - Paul videos are very interesting - thanks

https://wccftech.com/review/little-dot-mk-ii-review-miracle-tube-amp/

 

[ckhirnigs113]

Thanks to some very helpful correspondence with John Seaber at JDS Labs, I have finally come to understand that a preamp will not solve the hiss issue with the A100. A preamp can lessen the noise of a source. A preamp cannot do anything about the noise floor of an amp.

Since iFi said the iEMatch is not a good option for this purpose, I’m hoping the Garage1217 -20dB attenuator will be up to the task of handling the power of the A100. I sent them an email asking just that, so I’ll let you all know what they say.

 

[bequietjk]

Thanks to some very helpful correspondence with John Seaber at JDS Labs, I have finally come to understand that a preamp will not solve the hiss issue with the A100. A preamp can lessen the noise of a source. A preamp cannot do anything about the noise floor of an amp.

Since iFi said the iEMatch is not a good option for this purpose, I’m hoping the Garage1217 -20dB attenuator will be up to the task of handling the power of the A100. I sent them an email asking just that, so I’ll let you all know what they say.

yessss. totally waiting on them to email you back. that cable looks promising.

 

[ckhirnigs113]

I sure am delving deep considering I don’t even receive my A100 until Thursday. Maybe I’ll be one of the lucky ones that doesn’t have any audible hiss. I’ll still need either an attenuator or preamp if I want a decent amount of useable range on the volume knob with the jumpers installed using my HD58X.

Fingers crossed for the Garage1217 little cable!

 

[pngpng]

I'm happy to report that installing the L-pad attenuator did the trick! I'm very happy with how it's worked out. The noise floor is much improved and I'm getting more range with the volume knob to boot.
Didn't affect the sound quality at all to my ears. Same A100 goodness but without the slight hiss which is a huge win for me. I ended up using some MASSIVE wirewound resistors which will hopefully dissipate the heat better. I suppose someone could make an external box as well. There's still a hiss when the volume knob is very high, but in my case it's in a range that would literally blow my ears out.

As KeithEmo mentioned previously(link), the precise resistor values will depend on your headphone impedance, but he gives some general resistance values. I went with 7.5 ohm / 0.5 ohm resistors to keep the impedance down which is NOT advised since the resistors will get really hot. My resistors are installed inside the amp so I'm not too concerned. Still waiting for Keith's opinion on it though.

Edit: KeithEmo's response to my question:

The thing you need to remember with a voltage divider is that the power consumed by the voltage divider is largely independent of the power that's reaching your headphones.
And, with the values you used, MOST of the power will end up as heat in the resistors.
So, from the point of view of heat, you have an 8 Ohm load connected to an amplifier.
At full power, the A-100 can deliver about 50 watts into 8 Ohms...
So, if you were to play a test tone, turn the amplifier up until it clipped, and walk away, that 7.5 Ohm resistor would be red hot in a few seconds...
Old style wire wound resistors tended to have a positive temperature coefficient.... which is a techie way of saying that, once it got that hot, the resistance would go up, and somewhat limit the power.
(So, in fact, it might burn up, or it might just sit there and glow.... and set everything nearby that was flammable on fire.)

Of course, this is a very unrealistic situation, so I wouldn't actually worry that it will happen (if you floored the accelerator on your car for ten minutes your engine would probably explode too).
However, since your headphones are also somewhat efficient, that's probably not going to be a problem.

Just to be safe, I would probably keep an eye on them for a while, and note how hot those resistors get when you play something really loud.
(Remember that, since we're talking about continuous power, that means sustained loud bass notes mostly.)
I would also make sure and mount them with clearance... for example, don't have wires resting against them, or have them against anything plastic.
Wire wound resistors can tolerate a LOT of heat without significant damage.

I just wanted to make it very plain that using 10 Ohm half-watt resistors, with low efficiency headphones, and wrapping heat-shrink tubing around them, would be a really bad idea.
I wanted to stress that we're talking about an amplifier that is, literally, hundreds or thousands of times more powerful than a typical headphone amplifier.
(In order to be 100% safe with the A-100, even under test bench conditions, those 7.5 Ohm resistors would have to be 100 watts each, and mounted in a metal box with vents in the cover.)

However, odds are that, with normal music, and normal headphones, the ones you've chosen won't even get especially warm.
(But better safe than sorry.)

 

[KeithEmo]

You're quite right...

As with most small audio amplifiers with an analog potentiometer Volume control....
Inside each channel of the A-100 is an audio amplifier with a fixed amount of gain.
The amplifier itself has a fixed noise floor.
The input signal passes through the Volume control, which is a voltage divider, and to the amplifier.

If the source is noisy, that noise will be reduced when you turn down the Volume control.
However, the noise floor of the amplifier itself remains the same.
Under most situations, you don't notice the noise from either source.
However, if you do notice noise, which one is more noticeable simply depends on which is louder.

--------------

When you use attenuators for line-level signals, for example between a preamp and an amp, the amount of actual power involved is tiny, and can usually be ignored. In that situation 1/2 watt, or even 1/10 watt, resistors will generally be just fine, and that's what you'll often see inside line level attenuators.

Even the headphone amplifiers in most AVRs and smart phones really only put out at most a fraction of a watt.
So, an attenuator that you plan to attach to something like that doesn't see much power.

To put things in perspective:
If you were to connect a 60 Hz test tone to the input of the A-100...
And crank it up to its maximum undistorted output...
With the jumpers on...
Each channel could cheerfully deliver 50 watts into an 8 Ohm resistor.
After all, the A-100 is rated to deliver 50 watts per channel into 8 Ohms.
However, 50 watts is also the rated power of a typical bench-top soldering iron.
(So, if it all gets turned into heat, 50 watts is quite a bit of heat.)

At those same settings, if you substituted 32 Ohm resistors, each would only be getting 12 watts.
(This is why you really need to understand the math involved.)

I don't want to scare anyone...
And, in real life, with music, the situation won't be anywhere near that extreme...
But you can see how an attenuator, designed to handle a small fraction of a watt, might have problems.
So, if you don't know what's inside the little box, it is a good idea to find out for sure.
(Just tell the manufacturer that you want to connect it to the OUTPUT of a 50 watt amplifier...)

Thanks to some very helpful correspondence with John Seaber at JDS Labs, I have finally come to understand that a preamp will not solve the hiss issue with the A100. A preamp can lessen the noise of a source. A preamp cannot do anything about the noise floor of an amp.

Since iFi said the iEMatch is not a good option for this purpose, I’m hoping the Garage1217 -20dB attenuator will be up to the task of handling the power of the A100. I sent them an email asking just that, so I’ll let you all know what they say.

 

[bequietjk]

Just a heads up, I couldn't wait long enough @ckhirnigs113 for G1217 to get back to you, so I emailed them as well.

Jeremy got back to me and mentioned that it would be risky considering the subjective uses and variables involved with using their attenuator and the A100. However! He did mention that with enough interest, he could run a group buy for a special amp attenuator module. The amp module would be around 4x4 in shape and cost around $75. A month's build time.

What to do, what to do!?

 

[ckhirnigs113]

Just a heads up, I couldn't wait long enough @ckhirnigs113 for G1217 to get back to you, so I emailed them as well.

Jeremy got back to me and mentioned that it would be risky considering the subjective uses and variables involved with using their attenuator and the A100. However! He did mention that with enough interest, he could run a group buy for a special amp attenuator module. The amp module would be around 4x4 in shape and cost around $75. A month's build time.

What to do, what to do!?

I actually got a response from Jeremy at Garage1217 too, but his initial optimism that their adapter would work changed to hesitation after he double checked with one of his co-workers.

I almost quoted his email saying it’d be ok to use, but when I asked him if he was ok with me quoting him here he decided to delve a little deeper and changed his mind. I think the massive amount of power the A100 puts out could very easily damage the adapter they sell. Then again, this amp could easily damage most headphones too if you’re not careful with the volume knob.

Weather delays have prevented my A100 from being delivered, so I still haven’t gotten any firsthand experience with the amp yet. If it doesn’t have a ton of hiss when I plug my HD58X in, I’m thinking I may try those Harrison Labs 12dB attenuators first for $25 to have more play on the volume knob.

I am interested in the little device Jeremy at Garage1217 has in mind. I assume it would plug into the headphone out on the A100. What would the output impedance be? If he could remove the audible noise floor of the amp and keep the output impedance low, it may be the best option for a lot of us here. If the output impedance isn’t kept low, we might as well just take the jumpers out and use the resistors already in place in the A100. Pending the details on this little adaptor, I do like the idea of a group buy.

@bequietjk See if you can get some specifics from Jeremy and report back.

 

[vormhat]

I have the a100 and hd58x and don't hear any hiss. I don't even with my 80 ohm Beyers. It's when I go to portable optimized cans that I hear hiss like 32 ohm.

 

[ckhirnigs113]

I have the a100 and hd58x and don't hear any hiss. I don't even with my 80 ohm Beyers. It's when I go to portable optimized cans that I hear hiss like 32 ohm.

Do you have the jumpers installed?