FLUX Mentor Class-A dual-mono headphone amplifier.

[Slackaveli]

The volume control is based on a relay attenuator and contains 64 steps. The control circuit uses Panasonic fast signal relays with low contact resistance. The analog signal is fed to the relay attenuator located next to the input sockets, and the ALPS variable potentiometer (Blue Velvet series) is used for control only.

In my experience it is always the best option to use the gain setting that allows you to listen to your preferred volume with the potentiometer at about middle position or a little higher.

Yep, which is medium gain for me. Listening between 11:00 and ~2:00

As for low vs med vs high gain, i hear zero noise on all 3.

 

[LTd head]

In my experience it is always the best option to use the gain setting that allows you to listen to your preferred volume with the potentiometer at about middle position or a little higher.

Totally agree! If the volume pot is set over the middle position, more noise and distortion becomes audible.

 

[Inolvidable]

The volume control is based on a relay attenuator and contains 64 steps. The control circuit uses Panasonic fast signal relays with low contact resistance. The analog signal is fed to the relay attenuator located next to the input sockets, and the ALPS variable potentiometer (Blue Velvet series) is used for control only.

In my experience it is always the best option to use the gain setting that allows you to listen to your preferred volume with the potentiometer at about middle position or a little higher.

Thank you, Ichos, for your help. A quick search on the paragraph you highlighted clarified everything for me. I’m leaving it here in case it proves useful to someone else:

The volume control in a relay attenuator is analog, despite being electronically controlled. The attenuation is achieved by switching different resistor values into the signal path, which affects the signal's amplitude in a purely analog manner.However, the control mechanism—whether it's operated via a microcontroller, remote control, or a digital interface—can be digital. In such cases, a digital system sends commands to relays, but the actual audio signal never undergoes digital processing. This setup ensures high-fidelity sound without the potential artifacts of digital attenuation.

And thank you all for your input about the volume and the gain

 

[Daniel59]

And thank you all for your input about the volume and the gain

Here’s a little bit more info regarding the volume control on the Mentor amp. This info is direct from Flux, per my inquiry:

“
As for the volume control, all the steps of the volume attenuator are the same and are 1.5 dB. But there is a certain peculiarity. Depending on the speed of rotation of the volume knob, some steps can be skipped. This can significantly increase the service life of the relays used in the attenuator. In addition, the arrangement of the steps has a logarithmic dependence.

Best regards, Flux Lab Team”

 

[Inolvidable]

My Mentor finally arrived two days ago --a happy day indeed. Over the past 24 hours, it has been alternating between playing music for 4 to 5 hours at a time and resting for about an hour in between.

However, this morning, I woke up to a strong, industrial-like smell and noticed that the top of the amp was excessively hot—so much so that I couldn't touch it for more than a couple of seconds.

I had always assumed the Mentor generated minimal heat, so this behaviour has me a bit concerned. Based on your experience, is this normal?

For reference, the amp is placed on a dedicated shelf with proper ventilation.

Spoiler: Photo of my setup

 

[Ichos]

I don't think that is normal. Never experienced such issue. After all the heatsinks are located at the bottom part of the amp. The top should not get that hot.

 

[artist777]

I see that you have adapters installed in all the sockets. Perhaps they have a problem or are not inserted all the way, which is shorting the amplifier output. And it is very important that the adapter that is inserted into the 6.3 mm is not designed for microphones, that is, two-pin, not three-pin. This will definitely mean a short circuit at the output of one channel of the amplifier.

Spoiler: Photo of my setup

 

[SmartCheetah]

If the Mentor is anything like the M-Field in that regard, it's far from normal. My M-Field barely gets warm on the top chassis after several hours.

 

[Inolvidable]

Thank you so much for your input.

I see that you have adapters installed in all the sockets. Perhaps they have a problem or are not inserted all the way, which is shorting the amplifier output. And it is very important that the adapter that is inserted into the 6.3 mm is not designed for microphones, that is, two-pin, not three-pin. This will definitely mean a short circuit at the output of one channel of the amplifier.

I double checked the adapters and they were inserted all the way. I normally use the XLR socket but I had to test the 6.3mm one. The adapter is TRS, which I believe is the correct type (see spoiler). I have unplugged both of them just in case. If the temperature returns to normal, I'll let you know.

Spoiler: 6.3mm adapter

 

[SmartCheetah]

The adapter shouldn't be a problem if it's fully inserted. I've had a similar one plugged in all the time, unused, and never had any issues, even when using another one (4.4 to XLR) in the second slot.

 

[mRaaghava]

Hello all. My headphones are Clear OG and HE6SE V2. Which of these, Mentor and M-Field work better for my headphones, especially HE6SE V2?

Will use my DAPs, M8T or M11 Plus ESS as DACs for the time being.

TIA.

 

[Ichos]

Hello all. My headphones are Clear OG and HE6SE V2. Which of these, Mentor and M-Field work better for my headphones, especially HE6SE V2?

Will use my DAPs, M8T or M11 Plus ESS as DACs for the time being.

TIA.

My vote is for the M-Field. Better synergy especially with the Hifiman.

 

[Rattle]

I have clear OG and M Field and it's great synergistic pairing. DAC matters as well but it's a banging combo for me.

 

[Slackaveli]

Counter-point: I run He1000 Stealth on Mentor via Yggdrasil OG and it's freaking fantastic.

 

[mRaaghava]

I have clear OG and M Field and it's great synergistic pairing. DAC matters as well but it's a banging combo for me.

Which DAC are you using?