Sennheiser PC37X randomly goes bad after disconnecting the cable ?
Greetings, Yesterday I was using my headset like normal with my macbook, just listening to music and on a call with people like usual, and the headset was perfectly fine. The stock wire that came with the headset is extremely long and yesterday it annoyed me very much that it kept getting tangled with itself, so I decided to see if the cable is replaceable. I pulled out the cable from the headset and saw the adapter, and looked online for a replacement. Upon plugging it back in, the audio sounded extremely muffled and washed out. Im not sure what I did wrong to make it mess up like that as I've always taken good care of it, ive had it for about 2 years and its always just been chilling on my desk, but anywho I thought the cable just went bad and ordered a replacement. The replacement came, and the issue is still persistant, so I am not sure what the issue is I've tried multiple different headsets and the issue is not with the port, and I also tried it with my windows laptop and...
Apr 23, 2024
Measurements Patrick Flanagan at THX is one of those quiet guys who goes about his business with an engineer’s mind and a craftsman’s attention to detail. You may have met him at a Head-Fi meet in California as Jude Mansilla has been able to have him offer some free headphone or IEM measurements to the community on multiple occasions.
We met him at the 2016 SF Head-Fi Meet where he provided us with some measurements of IEMs we were working on:
New Technology The Massdrop x THX Achromatic Audio Amplifier (THX AAA™) 789 represents the next chapter in THX contribution to the audio world, where THX provides underlying circuit technology in the gear itself. The new design was born of necessity. THX needed amplifiers to power line arrays of speakers in their facility. Class A topology amplifiers run too hot and are inefficient to run for long periods of time. THX needed the cleanest signal possible, low noise, low distortion, cool temperature, and efficient power consumption. These requirements led THX and SVP of Audio R&D Laurie Fincham to revisit negative feedback designs, figure out how to implement feed-forward correction, and create the quietest, lowest distortion amplifiers.
THX Ltd. At-A-Glance: I. Highest quality sound for the utmost in cinematic experience (George Lucas’ original vision) II. Development and certifications for pro audio and audiophile gear (people like Patrick) III. Technological intellectual property in pro and consumer gear (Laurie Fincham’s amplifier design as an example)
A Series of Fortunate Events If we didn’t talk about Patrick, you might not know that THX is working every day behind the scenes to provide information to companies making audio gear…with and without the THX logo. And if we didn’t meet Patrick, this collaboration might not have happened.
Meeting Patrick at the event pictured above led to our visiting THX and seeing some of the measurement labs plus their demo room. (Fun stuff and just happens to be walking distance from our office in San Francisco!)
Visiting their headquarters led to an invitation for a sneak peek of the THX AAA feed-forward topology during the Rocky Mountain Audio Festival in Colorado 2016. We immediately saw the potential of this amplifier technology when we learned about it’s goals. Hearing the prototype- clean, clear, and natural (not sterile)...we knew that our community would like it too.
THX understands Massdrop’s connection with the headphone audiophile community and our drive to create custom-tailored products. THX collaborated with us to develop and bring this linear amplifier technology to you in this particular package, with the flexibility for in-ear monitors to large headphones. Capable for use in professional audio applications or for the audiophile that demands the most transparent upstream gear possible. This amplifier delivers the upstream quality of your music to your own personal headphone theater- in the comfort of your home or on your desk at work.
Massdrop x THX AAA™ 789 Linear Amplifier At-A-Glance: I. Lowest THD in class – world class transparency II. Extremely low channel crosstalk III. From low to high power – for your IEMs and your hard-to-drive headphones IV. Flexibility – from single-ended input/output to fully balanced throughput V. Form factor and usability - small, cool, efficient energy consumption VI. High value – high power and best performance at a low price point
By the way, we’re lucky to have Andrew Mason as a member here on Massdrop. Andrew is the THX expert in analog & power engineering who helped implement the THX AAA technology into our final product. If you have some technical questions about the amplifier, Andrew may just be around to answer them!
What tool did the team use to measure @143dB down?
I'm surprised to hear that the APx555 can measure that far down... that's a thousand fold improvement in power sensitivity over the advertised spec, if I'm not mistaken.
I would also like to know if I were to use XLR inputs, could I use single ended output and/or RCA output? I know you answered the inverse question yesterday about single ended input with XLR headphone output.
That all being said, I expect that this amp WILL sound very good. I'm just not waiting 8 months for the drop.
Odd-order vs even-order.
Higher-order vs lower-order.
"The results of this study indicated that within the constraints of this simple study that the perception of linear distortion is dependent on the level and the delay time of the linear distortion and the playback level. The first two main effects were known as indicated in the background discussion.. However, while it may seem intuitively obvious, the significant increase in the audibility of linear distortion has not been shown before. Further, that this audibility of linear distortion increase with both playback level and with delay time is extremely important. These results mean that a subjective impression obtained where playback level was not controlled is of questionable validity.
The combined effects of playback level and delay have strong implications to the perceived perception of nonlinear distortion. It is not possible to say, without complicated objective tests, if what is being perceived is a nonlinearity in the system or a nonlinearity in the subjective perception as described in this paper. This has profound implications to the subjective evaluation of nonlinear distortion in audio systems most particularly loudspeakers where the delay factor can be quite strong. Time delayed resonances, nearby cabinet reflections and edge diffraction, waves in horns; all have delay times on the same order as this study. A loudspeaker that is evaluated at 70–80 dB (SPL) may have a very different perception at 90-100 dB even if it is completely linear.
A THD distortion curve will not reveal this effect, nor will a frequency response graph. A careful look at the impulse response might yield the best insight, however this has not been quantified. Methods for measuring the nonlinear effects of our subjective perception are currently under investigation. Another point is that the usefulness of a loudspeaker for audio playback can have a sound power output limit that is independent of its electrical power handling or its nonlinear distortion characteristics. Loudspeaker evaluations that take place at a fixed level, are seriously inadequate at revealing the true quality of these systems."
-Lee and Geddes; Audibility of Distortion; AES 121st Convention, San Francisco, CA, USA, 2006 October 5–8
Where's the discussion? Sounds like a foregone conclusion.
My issue with some wall-wort designs is based on the fact that it's a pain in the neck to use on a power strip. Floor-wart isn't as bad for me; at least there's room on the strip for more connectors. But then the length of the cable has to be sufficient for me to find somewhere to put the floor wart without just leaving it hanging off a wall or desk or something.
Many people in headphone audiophile community like to have both a solid state and a tube amp of some kind to switch back and forth.
The power, distortion, etc specs say they are tested with 0db of gain, but the balanced output is not capable of even selecting that gain, its lowest is +6db gain. So are the specs listed under the balanced output measured at +6 or +0db? Also, are the gains different for SE and Balanced simply because of how the balanced signal works? Or are they running through seperate circuits with different gains?
What is the voltage swing of the amp? I like seeing the power specs, but it is nice to know what the voltage is so I can judge how much current it also has behind that signal to be pulled when needed
Lastly, since testing was done with 300ohm load, does that mean this amp is "best suited" for that load? I see you mentioned 12 ohm load as a minimum is fine, is that the amps actual recommended safe minimum?
The specs are really fantastic, but I am suspicious about whether these are measurements of the underlying topology, or measurements of this specific Massdrop implementation . The single voltage DC-in implies the use of a rail splitter, and those kinds of measurements are pretty unheard-of with such a power supply implementation.
I'd love to hear your comments about that, and apologies if my assumptions are off.
Best, Daniel.
- Replace the stateless push button with a real on/off button, so that the amp can be made to automatically turn on when main power is turned on when the button if left in "on" position
- Alternatively to the above, add an "auto on" feature to complete the "auto off" one
- raise the max current limit a bit, maybe adding internal heatsinks where needed
Other than that I find that amp perfect! Kudos to @AndrewMason and massdrop, once again :)