[KaiSc]

What this seems to be assuming here is that all units share the same level of hiss. @KaiSc What do you think about the possibility that units could have a range of noise decibals such that a number of units fall on the extreme upper ends of the spec bounds and are thus quite audible?

This is my theory. That the spec is too loose and there are units on the upper end of the spectrum where consumers like me and some other find it unacceptable. I think the quality is sufficient overall that were we to receive replacement units it is likely we'd receive units without the problem.

You are probably indeed correct that an existing unit would not be fixable through means that made it more economical than total replacement. The components themselves have quality tolerances that add up as well. It isn't always just a single component that is responsible for exceeding the spec.

With a sample number of 2 my experience is far from being representative.
But those two are so close together that I am willing to guess that the variation range is not very big.
Of course it's always possible that someone gets an outlier or something breaks after delivery.
Today electronic components are very consistent in specs so I would not expect large variations here. If at all, the drivers could have some differences in sensitivity.
I am willing to measure a few more that people suspect to be out of spec's.
If someone is interested PM me, I am living in Germany.
You have to pay for shipping in both directions.

The mod I suggested can be done by every experienced electronics guy ( like me ) if AUDEZE is willing to share some information with us.
Of course I could figure it out by myself, but I have no reason to do that with my own unit.
It's just about replacing or bridging two resistors.

 

[KMann]

@KaiSc - Thank you for your post. What you have stated is very much in line with our finding.

Thank you so much for your clarification. Very helpful.
I hope @Audeze @KMann is willing to share with us a way how to this “tinkering” without having to send it back.
I really do not need the maximum gain and I would be extremly happy to trade it against no hiss.

Unfortunately there is no way to reduce the Amplifier gain without a hardware change, if there was such an option we would have already provided it.

 

[KaiSc]

@KaiSc - Thank you for your post. What you have stated is very much in line with our finding.

Unfortunately there is no way to reduce the Amplifier gain without a hardware change, if there was such an option we would have already provided it.

Sure, but the change is simple and can be done outside AUDEZE factory.
Of course it would help to get some information from you which components to change. As I mentioned, it wouldn't be a big deal for me to find out by myself, but with deeper inside on the construction AUDEZE could give a hint, and changing the gain of an amplifier can lead to instabilities sometimes if not done properly ( AUDEZE already did that ), so why should I bother and investigate this by myself?

There is at least one person here in Germany that would be interested to let this done by me, instead of going through the hassle of sending the headphone to USA and back.
You could even instruct your local representative how to do it, if you have one in Europe.

 

[bfreedma]

Sure, but the change is simple and can be done outside AUDEZE factory.
Of course it would help to get some information from you which components to change. As I mentioned, it wouldn't be a big deal for me to find out by myself, but with deeper inside on the construction AUDEZE could give a hint, and changing the gain of an amplifier can lead to instabilities sometimes if not done properly ( AUDEZE already did that ), so why should I bother and investigate this by myself?

There is at least one person here in Germany that would be interested to let this done by me, instead of going through the hassle of sending the headphone to USA and back.
You could even instruct your local representative how to do it, if you have one in Europe.

Doing that would surely violate the warranty. I doubt any manufacturer wants to be in the untenable position of publicly documenting a change that would do that.

 

[KMann]

Sure, but the change is simple and can be done outside AUDEZE factory.
Of course it would help to get some information from you which components to change. As I mentioned, it wouldn't be a big deal for me to find out by myself, but with deeper inside on the construction AUDEZE could give a hint, and changing the gain of an amplifier can lead to instabilities sometimes if not done properly ( AUDEZE already did that ), so why should I bother and investigate this by myself?

Voiding the warranty aside, you would have to break the seal when you remove the driver from the ear cup. Breaking the seal will have an impact on SQ. Also the components are SMT, not a simple DIY job. You will need the circuit schematic and the values to change. Unfortunately we will not be able to support it. The Hardware change will also require a firmware change to go with it.

 

[KaiSc]

Voiding the warranty aside, you would have to break the seal when you remove the driver from the ear cup. Breaking the seal will have an impact on SQ. Also the components are SMT, not a simple DIY job. You will need the circuit schematic and the values to change. Unfortunately we will not be able to support it. The Hardware change will also require a firmware change to go with it.

Aside that I'm working with SMT or SMD circuits quite often and that a seal can be restored.
I might be wrong on this as this could overdrive the DA:
Asumed that the firmware change is probably additional digital gain to compensate for the analog gain change - this is not necessarily needed for those with sensitive ears.

For a mod one would not need a complete schematic, just a layout plan to locate the feedback resistors of the amp or any other part that makes sense to change and info about the seal if it's very special.

There are 19 people here in this poll hearing the hiss so AUDEZE could think about what to do to satisfy those.
As mentioned I am not hearing the hiss, it's been others I wanted to help.
Maybe you have a service point in Europe.

 

[Richter Di]

What this seems to be assuming here is that all units share the same level of hiss. @KaiSc What do you think about the possibility that units could have a range of noise decibals such that a number of units fall on the extreme upper ends of the spec bounds and are thus quite audible?

This is my theory. That the spec is too loose and there are units on the upper end of the spectrum where consumers like me and some other find it unacceptable. I think the quality is sufficient overall that were we to receive replacement units it is likely we'd receive units without the problem.

You are probably indeed correct that an existing unit would not be fixable through means that made it more economical than total replacement. The components themselves have quality tolerances that add up as well. It isn't always just a single component that is responsible for exceeding the spec.

@CosmicConcerto I guess the only way to find out would be if you take the plunge and send your Moebius to @KaiSc. I am fully aware that this would mean much more financial investment to get it send and re-send plus the possible paperwork from the US to Germany. But in any case only if we measure at the same place we can be sure.
I did it but it was much easier for me to send it inside Germany.

 

[Richter Di]

Voiding the warranty aside, you would have to break the seal when you remove the driver from the ear cup. Breaking the seal will have an impact on SQ. Also the components are SMT, not a simple DIY job. You will need the circuit schematic and the values to change. Unfortunately we will not be able to support it. The Hardware change will also require a firmware change to go with it.

I will keep mine as it is and hope there will be one day a Mobius 2.0 without the hiss. In case @KMann you need a sensititve ear, I am happy to listen to the prototype of 2.0.

 

[acia]

If it is sooooooo easy. Why not just build your own?

I am lost.

Have you heard of something called proprietary?

Scematics on the silver platter for free would be lovely.

 

[Richter Di]

If it is sooooooo easy. Why not just build your own?

I am lost.

Have you heard of something called proprietary?

Scematics on the silver platter for free would be lovely.

I guess this a misunderstanding, most probable as 2 German guys do not speak natively English.
So @KaiSc never asked for the full scematics but only the place where the electrical resistor is placed to regulate the amplification inside the DAC.
So, nobody says it is easy and when I phoned with KaiSc he was full of respect for the technical advanced work Audeze are doing. So no harm done in asking if he could switch out two resistors for another headfi person to help this person.

 

[KMann]

I guess this a misunderstanding, most probable as 2 German guys do not speak natively English.
So @KaiSc never asked for the full scematics but only the place where the electrical resistor is placed to regulate the amplification inside the DAC.
So, nobody says it is easy and when I phoned with KaiSc he was full of respect for the technical advanced work Audeze are doing. So no harm done in asking if he could switch out two resistors for another headfi person to help this person.

For the record @KaiSc has been very helpful and supportive, the requests are valid, just that we are not comfortable supporting it.

@KaiSc I will discuss this with our team.

 

[Richter Di]

For the record @KaiSc has been very helpful and supportive, the requests are valid, just that we are not comfortable supporting it.

Which I can fully understand. This is not the first time that my "hiss" ear has brought me in "trouble". So I usually sell that stuff or get someone to alter it for me, like for the CEC HD 53 N headphone amplifier from Carlos Candeias. Or a headphone amplifier inlcuding DAC called Opera from Meier Audio, where I had the prototype and the serial model. The serial model had some hiss, while the original prototype had not. But the serial model was smaller. So I was able with some mumetal foil to get rid of the hiss. You see my ears bring me in a lot of trouble

 

[Runo]

If your answer is "yes" do you consider it an acceptable amount of noise floor for an active amp headphone as Audeze claims?

The reason for this poll is simple. Some users have complained about this issue post-fix. They have sent their units back to Audeze who claim the units are within spec.

I would figure something "within spec" would not be obvious. I can hear it, and I've worked the last 10 yrs in a high noise environment and I do NOT have superhuman hearing. If I can hear it, then my unit must be above spec or there would be more complaining among the masses.

Yes, I do hear a noise floor as long as nothing's playing. But no, it doesn't bother me; it's quite quiet, and has a pleasant frequency profile, so for me it vanishes as soon as there's anything else playing, especially if I don't actively focus on it.

I am willing to measure a few more that people suspect to be out of spec's.
If someone is interested PM me, I am living in Germany.

Maybe I can get mine to you sometime. I live near Reutlingen, so not too far away anyways. Although I don't really wanna give them up for a week or more at the moment!

 

[KaiSc]

Yes, I do hear a noise floor as long as nothing's playing. But no, it doesn't bother me; it's quite quiet, and has a pleasant frequency profile, so for me it vanishes as soon as there's anything else playing, especially if I don't actively focus on it.
Maybe I can get mine to you sometime. I live near Reutlingen, so not too far away anyways. Although I don't really wanna give them up for a week or more at the moment!

As you describe it the hiss may well be at the same level as the other 2 I've measured.
How would you judge the state of your hearing and how old are you?

 

[Mani ATH 87]

I can hear a slight hiss on mine when connected via aux with the volume near max.

When connected via Bluetooth or USB there's no hiss that I can hear at any volume level when turned on.

I have no issues with hearing loss or anything of the sort.