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
As an enthusiast myself, the coolest thing at Massdrop is getting to work with and know the people who make our favorite stuff. I’ve had the privilege of being able to speak with and learn from Alex Cavalli over the past year while working on this new amp with him. I understand more about the design decisions in amplifiers and what’s possible given different goals and constraints. (Though Alex would probably half-joke that “it still isn’t much”.)
Entry-level End-game Amp? Is that a category?
This project started out as a conversation to take a community-favorite DIY amp engineered by a community-favorite designer and make it accessible at an entry-level pricepoint. But when the prototype arrived, it had been completely re-worked by Alex. In comparison to the original Compact Tube Hybrid, it was a whole new amp. Sticking to the original vision, we worked toward the most accessible pricepoint possible while keeping the high-end sound that Alex passed down from his more expensive and more powerful amps. The amp needed to be audiophile-approved, more affordable, and simple to use. It also deserved a nice chassis, one that has some room in it and some stackability…
I’m sure there will be a lot more discussion these next few weeks. We’re working with Alex to have some information for those interested regarding the differences between the Compact Tube Hybrid and the Cavalli Tube Hybrid. Alex happens to have some travel during the drop so we may have a Q&A session where we’ll collect questions and Alex will answer them during the second half of the drop.
This is an important step for Massdrop, it marks the evolution of our ability to work with the best partners and designers to bring you the best versions of products for our communities. Each one of these collaborations is the result of our coming together to keep growing and moving our hobby forward.
Thanks for your participation!
EDIT 8/12/17: Here is a link if you are interested in the differences between the original COMPACT Tube Hybrid and the new CAVALLI Tube Hybrid. https://www.massdrop.com/talk/2167/the-massdrop-x-alex-cavalli-tube-hybrid-in-with-the-new
Anyway, I'm super excited to read about this. It's always nice to see better and better quality equipment and technology trickle down into packages that are more and more accessible at lower price points than ever seemed possible ever before. This product sounds like it's built on strong heritage with amazing technology as well as great goals in mind for marketing and pricing.
Massdrop has truly done an excellent job on the vast majority of their collaberations here in the audiophile world, both in quality, and pricing and accessibility, and I'm genuinely grateful to have the chance to be a part of this community and to help it grow more and more as time goes by.
A true thank you to Massdrop for always trying to listen to the people and respond with high-quality offerings that attempt to address the community and their collective wants and needs. Here's to hoping for a continued successful run of current and future collaberations within the community!
First, I have to say what a great pleasure it has been to work with CEE TEE and the MD team. We've been working on this little project for quite a while and everyone at MD has been dedicated to making the best product we can make at a price point that is affordable to most people.
Another thing about this project has been the opportunity to bring back one of the DIY projects and make it available to the community where all of my work was started.
Some have wondered about quality of product. Here are some things to know.
This version of CTH is a new design, entirely mine. It's a significantly beefed up version of the DIY CTH, which was, during its time, a fairly popular project. It sounded pretty good too. But the original CTH just doesn't have the power to deal with some of our modern planars and its circuit technology is a bit out of date.
For those of you wondering, I built all of the prototype boards as we progressed towards the final version. I also designed and laid out all of the boards, including the production board that you will receive, and specified the board fab parameters.
All of the parts in the amp are specified by me and there are no subs without my approval and collab with CEE TEE and the team. This applies to the production pieces. The component quality in this amp is equal to the quality in the Liquid Carbon.
I think that MD did a really nice job on the box. It is clean and simple, but with some very appealing details (like the vent holes). As some of you have discerned it is stackable.
I believe that you will find that this is a well made product.
I hope that those of you who eventually buy the CTH will also find that it's a really good entry level amp that, perhaps, out-punches its weight class. At least I can believe that will be the case while I am hiking around Yellowstone NP over the next week ducking geysers and bears. :) :)
This is the one spec that concerns me. I noted that one of the reviewers commented that with a 'hot source' he would 'trigger the protection circuit' when he cranked the volume, and that most of the time the volume control was only used between the 8 and 9 o'clock positions. How difficult would it be for users to modify the gain?
Does the amp have a fixed max output voltage? The power output spec given here seems to indicate a max output of just over 7v but I'm not sure if that will apply across other impedance levels.
Keep what's called the open loop gain (the raw gain) fairly low. Then apply the minimum NFB that is needed to achieve the closed loop (actual gain) that you need. That is, the less NFB the better. There are a number of trade-offs here too, including the final THD, IMD, bandwidth, and noise.
One fairly uniform result of too much NFB seems to be a sense of loss of imaging (depending on how well the NFB is done). This is generally easily discernible if you can A/B the exact same amp with different amounts of NFB.
As an aside, way back in the 1970s and 80s when transistors had fully replaced tubes in power amps, there was a very common amp topology that nearly all manuf of retail hifi (including cars) used. These amps generally used very large amounts of NFB to get the THD into reasonable limits. The problem was that they tended to all sound the same and this sameness was due to the high amounts of NFB.
The other set of trade-offs is source output levels (which tend to be fairly high these days MHO is that the source outputs are generally too high for the headphone world), pot rotation to get a comfortable listening level, and headphone sensitivity.
It is nearly impossible to satisfy all of these conditions at the same time for every possible source and headphones and their combinations. So every amp is a set of choices that the designer(s) makes to hit the product targets and to work well with as many combinations as possible.
I have found with the bigger amps that a gain of 8X seems to hit the best spot in this parameter space (at least for the topologies that I've used for my amps) and sources and headphones that are available to us (which is a huge number). I suspect this may be true for many, but perhaps not all amps. And by best spot I mean flatness of freq response, imaging, resolution, clarity, musicality, THD, etc.
The only exception to this has been the Carbon which was designed from the start to have unity gain (1X) so that it could be useful driving IEMs.
It is not easy for users to mod the gain which involves swapping a few components on the board. Although it could be done. Might void MD's warranty though. :)
The CTH has a maximum peak voltage excursion of 10V (1WRMS @ 50R). It should apply to all headphone impedances that I know about. Although you might not think so, 1W is a lot of listening power even in the speaker world. I have played LCD2 out of the amp without difficulty (although it is not the most power sucking headphone around).
Other amp designers will, of course, have their own thoughts about this.
Does this help??
To be honest I'd been assuming that the gain could be altered quite simply just by changing a few resistors or something similar without affecting the overall sound of the amp. However after posting my query to you I actually went and read the article about the new amp linked by CEE_TEE in the top post and realized it was probably a bit more complicated than I'd thought :)
Would I be correct in concluding that while the gain could be changed by exchanging a few components it would have more effect than simply altering the gain, and that altering the gain would therefor also necessarily alter the amp's sound signature?
Regarding the output voltage, again thanks for the clarification. Would it be safe then to use the following formula to approximate the amp's max output power into varying impedance loads:
7.07 / Z x 7.07 = W
Where 7.07 is the maximum rms output voltage and Z is the impedance of the headphone + amp, or are there other factors that need to be accounted for? I guess at some point the output must become current limited, either by design or by destruction of the amp :)
The change, however, is really only a matter of two resistors.
Formula is correct. Easier for head calcs to use W = 50 / Z. [RMS Power = (Vp * Vp) / (2 *Z)]
The PS has a fair amount of headroom so I don't think you will hit a current limit unless Z is something below 20R (approximately). Usually, the lower the Z the more sensitive so we generally get to unlistenable volumes before we hit the limit.
Rather have my boy alive and no amp, but I'd jump on anything @AlexCavalli offers whatever the price - I soldered up 5 of the old CTH kits for friends back in the day and they were an excellent product for both the time and the price.
While times have changed, this amp has too, and the changes are both sensible and fairly massive. It's too unassuming in looks to be called a beast, but I'd say >90% of people who buy it will be delighted with the purchase. Of the rest, some will know and prefer a different acoustic signature, others will compare to their favourite product at a much higher price and decide it's good for the money, and the rest simply can't be pleased.
I'd love for it to have a remote as I'm not earning (spinal cord injury w/ painsomnia and other issues ruined my ability to do so), but for cost and quality it's otherwise perfect for my wants
At least Alex knows what it is to put his sons needs first - by all accounts it's how he got into the business!
I for one am very happy to see products like this on Massdrop. This is why I stick around. I might not like the long delivery period but I've been very impressed with all of the Massdrop collaborations I've purchased.
I know nothing about audio but I respect you and your greatness for many reasons as stated in the comment section but one is undoubtly undeniable because of MassDrop and this collaboration between you two.
I want this but I don't know if I can appreciate it. At least I now know who you are and if I ever jump into audio, you're at the top of my list. Take care.
To be more specific, every active device (and even passive ones) introduce non-linear effects into the amp. Every single one. A large part of the work that amp designers have been doing for decades, if they are tying to make good amps, is dealing with these non-linearities. Many, many methods have been devised for this.
So one can argue in the simplest sense that ---- if every device adds non-linearity, then the fewest devices needed to get the job done is the best solution.
See the post somewhere about gain.
With dynamic headphone amps we don't need a lot of gain. In fact, most of the time, we don't need any at all.
Sometimes we can get all the gain we need with a single triode gain stage (1/2 of a 6922). If these is all the gain we need then we shouldn't needlessly complicate the amp any further with respect to the voltage gain.
Solid state amps are similar. One active device usually has enough voltage gain for a headphone amp.
Then there is the current (or power gain). That is, the output stage doesn't really need to amplify the voltage any further, but it does need to provide the current required by the headphones. Which, in the dynamic headphone world means dealing with loads anywhere from around 16 ohms to 600 ohms. Every impedance in between these two extremes will demand different current capacity from the amp.
So, in nearly all dynamic headphone amps (and non-electrostatic speaker amps) you're doing two things, amplifying voltage and amplifying current.
Another post to follow..................
I am about to way over simplify and leave out details....
In general tubes are good at voltage gain, not so good at current gain. SS devices can do both.
If you choose all SS you have devices that can, therefore, fairly capably meet all the design needs.
If you use tubes at the input for the voltage gain and SS for the output current gain, you have used each type of device in a situation where it is highly capable. This is a hybrid.
If you use tubes for both input and output you are using tubes in the output stage where they are not especially capable, particularly because they may not have the current capacity. This is a tube amp and the limitations on the output stage can lead to things like HF rolloff as the headphone impedance goes lower and lower. I am referring to direct coupled or capacitor coupled tube output stages. I'm leaving out transformer output.
So, IMHO, there isn't really a purist type solution here. It's just a matter of implementing the design to use the strengths of the various active devices that we can buy from global electronic component manufacturers. Fortunately for us, this is an immense variety of stuff. :)
MusicisGreat, I think your question refers to my third alternative. This would be a multiple tube design and it can sound really good if design well or exhibit the limitations described above if not.
To complicate things even further, my over simplification has left out the fact that even in pure tube amps (these days) SS devices are often used in various elements of the circuit as auxiliary circuit elements. So you may think a tube amp is a pure tube amp when, sometimes, it's been polluted with SS devices. :)
In my non-Massdrop life, I have mostly designed and made available hybrid amps because I think they combine the best of both worlds, nice tube voltage amplification and good SS current amplification. The net result of this can be a very nice, transparent type of sound, which blends the best of tube and SS.
One more to follow.....
Even though we generally only need the voltage gain of one device (in the headphone world) we can't always get away with that. And for current amplification we can't get away with that either. And the principle reason is that the non-linearites of that single device are unacceptable.
And so, to state what you all obviously already know, an amplifier has multiple active components which are deployed together to achieve the two necessary gains, while managing as best as possible the various non-linear effects of everything in use. Looking at the history of amp design, with the many brilliant amp designers over decades, many of them have done a pretty good job of it.
I suppose my first answer would be, why would we aim for low linearity? I think what most designers aim for is something like this:
For the particular purpose of this amp, with the particular topology of the amp, within the engineering and manuf cost budget, how can I optimize all of the non-linearities (which we cannot completely eliminate) so that they each have as little audible effect as possible or even negligible effect. Effect on the wide ranging human experience of listening to music through electro-mechanical devices. One example of negligible might be the measured THD which no human ear, at all relevant frequencies, can hear and beyond which lowering the THD has no real practical effect.
Does this help? If not, let's try again.
Alex answers, on trip or not. That's on him. I'm only suggesting some courtesy.
And honestly I feel like some of these questions in general are far above the price point for this amp. But that's just me.
I previously noted that with HE-500 and a hot source (Modi MB) the CTH would activate the protection circuit if I turned the volume well past my comfortable listening levels. The HE-500 is my hardest headphone to drive. Not as hard to drive as an HE-6 but much harder to drive than a Sennheiser.
I tried this without the headphones on to see what would happen/how far I could turn the pot. Alex has stated that there is protection circuit will activate if the amp sees a current level that it deems as potentially damaging to headphones.
Testing this specifically again since I just got home, here is how hard I can drive my HE-500 (NOT on my head): -With RSA F-117 phono preamp at it's normal minimum gain setting while being fed from an Ortofon 2M Blue cart, I was able to get full range on the volume pot without activating the protection circuit on the CTH. At max volume, the HE-500 was able to produce about 102 decibels as measured by an iPhone app with the microphone placed near the point where an ear would be. -With a Modi MB, which has a higher output level than the RSA F-117 at its minimum gain setting, I can get the volume pot to the 4 o'clock position before the protection circuit kicks in. At this point, the HE-500 produces about 106 decibels before the protection circuit activates.
I cannot really think of any sane person that would listen to music at these levels.
Also, as update to another comment I made about my listening to position on the volume pot, when I say I listen to music at lower volumes than 90% of most listeners, I mean it. When I listen to music on my JH13 or Noble X from an iPhone, my sustained listening is done on the second or third bar. Also, I had to return a DragonFly Red and Black because the volume was too loud for me at the lowest setting on both of these with IEMs. (I've mentioned this with the DFR elsewhere and have shared my thoughts about this with the Audioquest team.) I find this experience of mine to be true with full sized headphones, too. Perhaps I'm in the >99% category rather than the 90% category here. Regardless, the CTH was able to deliver balanced volume levels at low listening volumes while offering me the control I desire.
I don't recall mentioning "never measured" artifacts or things that have never been scientifically observed. I have only said that there is an array of well-known and and measurable non-linearities (or other parameters like Zo) which a designer can manage in various ways for whatever his purposes are in designing a particular amp.
I think my previous comment summarizes it.
Stop man. You are now a pest.
The lack of respect is mind boggling.
If you know so much. Make the God damn amp yourself.
Alex I'm sorry. But if this is the kind of tolerance you accept. I'm out. There is only so much you can say especially considering your stature. Feed him more and you only perpetuate tolerance of which I cannot abide by.
His account was created a year ago, and he's never participated in a single drop.
http://knowyourmeme.com/memes/sea-lioning
If your single purpose is to get an answer to that question because you feel it is a form of false advertisement. I can respect that, but at the same time, it's just getting boring now, I have lost interest in this drop and your posts.
I have made a lot of assumptions, I might be completely wrong in everything I have assumed in regards to the majority of people in on this drop. But that is why I am BrainFlush. I apologize if I offended anyone.
It's definitely sealioning... or some kind of internet neurosis.
Take care.
I also somewhat get what he's asking. And his last response was decent enough that I truly hope he gets an answer. I didn't want to placate him or silence him. Let's see what happens.
I can tell all of you, however, that the solar eclipse from the middle of Wyoming was downright spectacular. :)
I am happy to have further discussion, so long as we don't take up a lot of space from other people.
To start, how about if we just discuss THD? And before I try to answer what I think you are asking, perhaps you can tell me what you think THD is in an amplifier and how to measure it. Then I think we can have a good conversation.
Your last sentence is ironic as Alex is the qualified mathematician that you have been talking to for days. Which you refuse to take his explanations because someone, somewhere said something that you may think contradicts him.
Show me your PhD and then I'll spend the time going over your math.
At least this isn't someone asking for the millionth time why don't Massdrop ship to country X.
Caring about serial number thing is weird (imo lower serial numbers just means higher chance of a QC issue!) but at least it's not asked as frequently.
#10001 would be cooler though, it's a palindrome number.
The one about reliability- that was mostly facetious. The one about a bunch of early products going to reviewers- well, pre-launch review products have turned up on the forums, and most drops specify a buffer of 50 serial numbers for the first X buyers (some do specify that serial #1 will be released). The one about fantasizing about serial numbers on discounted to consumer, mass market goods being misguidied- that one is a matter of opinion.
That note could be a clear indication serial numbers matter to some. For me, it's simply the lower the number the cooler it is. On an already amazing build, I think it's pretty neat. No more no less.
If you're going to be a snob, be a snob over something properly exclusive!
Though even then, a bespoke suit or custom furniture is a pretty low bar.
nah. nothing wrong with being confused about the seemingly random MD shipping policies. Dorking out over freaking serial numbers is just plain stupid.
Admittedly I only discovered this because I was wondering if Massdrop even bothered to put a serial number somewhere on the case.
Case is nicer than I expected- the walls are nice and thick, the volume knob is pleasantly smooth. The front button is the only bit that really feels cheap (light and hollow actuation, but at least it doesn't wobble).
Can't seem to find much info on the circuity in the amp. Any possibility of a Massdrop schematic or a current link to some more information on the original Compact tube hybrid ? This amp sounds so good that I'm thinking it might be worth modding to get the last bit of performance out of it.