Massdrop Cavalli Tube Hybrid Amp

Although I agree with your assessment of the character of KG, of course I can't find the post now, but there was a graphical snapshot of the input and output sinewave that showed it clearly 180 degree polarity flip.

And of course I don't use a dedicated computer anymore for music enjoyment. Just the Raspy Pi, and sadly no polarity flip. I will try to see if there is an ALSA mixer command or something.

 

One thing about absolute polarity. Most producers do not pay any attention to absolute polarity when making their recordings. In fact, some persons who are sensitive to absolute polarity have reported that albums can have one track in phase and the next 180 degrees out of phase.

 

Answers:

MCTH 4-pin XLR and TRS connectors are wired in parallel as verified with DMM. 4-pin XLR pins 2 and 4 are tied together to shield of TRS connector.

Output polarity is inverted from input on both channels (picotech 5243b oscillosope).

Input is 20 Hz sine 2Vpp.
Trace colors
Blue Input
Red Output

MCTH left channel with 300R load


MCTH right channel with 300R load

 

I have Jriver on 1 pc using USB into the dac1321. Lo and behold, LMS has phase reversal for my pi/502dac/spdif. I'll be back....

Gotta thank that headcase guy for his observation. Sat thru multiple playback of tracks from Cassandra Wilson.
A great way to start the day. , Inverted phase or normal, the results were equally extraordinary, no difference.
New Moon Daughter was awarded a grammy and it was well deserved.

 

If you're bothered by this and are using a plug-in capable player that doesn't have an innate phase/polarity inversion capability, then DMG Audio have a nice, free*, little plug-in called "TrackControl" that can, among other things, invert the phase of both channels (or a single channel, if you want to play with the "Phase Reversal Trick").

There are versions for both macOS and Windows, for most common plug-in formats.

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*You have to create an account to get it - though even as a paying customer I don't think I've ever received an email from them about anything.

 

Here's an absolute polarity test to see if it makes an audible difference in your system (or to your ears, for that matter):

https://www.audiocheck.net/blindtests_abspolarity.php

The first time I did the test (on my monitors) I thought I could tell the difference and was 98% correct. Now coming back after lunch it sounds the same and I am randomly guessing, so I may have just been lucky the first time. Who knows.

 

I cannot hear any difference thanks for the link.

 

Isn't the Crack and the Darkvoice 336-SE also inverted outputs? See? Nothing to worry about.

The only way I got a 98 on that test was the non-inversion had a "tell" near the beginning. That was MSR7's just using the headphone put on my work computer.

 

The inverted absolute polarity isn't a big deal. Most people aren't going to notice. The effects of inverted absolute polarity on headphones is subtle, and only really noticeable if you are using good suitable headphones along with a good source.

What I didn't mention in my listening test with Daft Punk's Random Access Memories is that I was using a LCD-2 Classic. The Audeze headphones have an ability to let me better hear the envelope and pillowing effects that I hear in the high-res version of RAM. The Audeze planars are just very good at making that audible and noticeable. It's a planar thing and a reason why I so much like the Audeze planars (I really really like them because of this). My HD650 let me hear that envelope and pillowing, but not as well. My Fostex/Masscrop TH-X00 pretty much don't let me hear that envelope and pillowing thing barely at all (the TH-X00 is super fun to listen to but is not what I use for critical listening or for trying to hear the benefits of high-res or polarity or phase issues). Source is also important in whether you'll notice absolute poliarity issues or not. The Schiit multibit DACs are good for letting you hear absolute polarity and some other DACs are not so good at that.

If you have the right amp, right headphones, and right DAC/source, and know what to listen for and are sensitive to that then you may notice changes in absolute polarity. Most people won't.

The main difference I hear with high-res over CD is that envelope thing, and it's subtle. High-res tends to have that style of envelope around the sound when you listen using a headphone like an Audeze with a good amp along with a good DAC. That envelope thing also depends on maintaining proper absolute polarity. Invert the absolute polarity and that envelope tends to go away. So for me, yes I care about absolute polarity and whether gear inverts absolute polarity when listening critically. But 99% of the people buying this amp aren't going to notice or care. Those that do care will know how to deal with it once they know the amp inverts absolute polarity.

One thing I like about the MCTH is that it's an amp that allows me to hear the envelope and pillowing in the high-res version of Random Access Memories and similar high-res recordings. There are a lot of inexpensive and expensive amps that don't. I like amps that do.

 

So, my two main amps are inverted, eh? Ignorance truly is bliss. I'm simply not going to worry about it any more. That makes 2 well renowned designers who chose the inverted route. I'm sure for good reason. 2 great sounding amps.

 

I really like this amp, and think it pairs well with a variety of headphones. Two particularly good pairings are the Audioquest Nighthawk and Nightowl, which is surprising to me, as I usually don't use tube amps with these headphones for obvious reasons. The have a nice, expansive sound with the CTH, and the overall sound is quite lively. The Hifiman HE-560 is also good. Hifiman's, with the FocusPad-A's, just have this amazing ability to both have great treble extension and clarity while also sounding really smooth and almost soft (tracks were from Einstein on the Beach). However, one pairing that is not preferred is the LCD-2C. Not sure what it is, but it just makes it sound wonky. A quick switch to the Grace m900, and it's back to being a great headphone. The LCD-2C sounds great with the Magni 3 as well, with the Dragonfly Red as the source.

One thing of note is the volume pot has developed a pretty annoying static scratch when adjusting the volume, and I have only had it for a few months.

 

The three designs referenced didn't choose to invert the signal as a primary design goal. They chose to keep the topology signal path minimal. In order to achieve a non-inverting output with the referenced circuit topologies would require an additional active stage. Every time an active stage is added more residual noise and distortion are created as a consequence. So which would most people prefer, greater clarity, lower distortion and lower noise with less active stages or have absolute phase? I would choose the former every time.

 

Can you elaborate on how to do this in LMS? I'm also using a Pi as a source.

What is this "envelope and pillowing" you keep mentioning. Quick search turns up envelopes and pillows.

 

I use picoreplayer on my pi. If you use a different software it may not be available. Anyway, this is how I do it.
Open LMS. I use a browser on my windows desktop. Click on the settings gear in the lower right corner. The setting window opens pick the highlighted choices.Voila!

 

The LMS package for my Synology NAS doesn't seem to have that setting (7.7.3-203). I'm running an older version of DSM, so that might be the reason.



Doubt I'd be able to hear the difference anyway. I have a polarity switch on my micro iDSD and played with the "polarity corrected" version of Skylarking ... no effect.

 

So I tried changing my polarity and I think I hear a soundstage difference...being wider with out of polarity vs in. I can't even decide so really I don't care at the end of the day lol.

 

As a result of this thread, I checked whether the ground prong of my AliExpress LPS is connected to anything. It isn't.



Since I have it open, took some pics of the inside.

 

By the way, polarity issues we as all talking about are audio input and output, not the 24V input. Just wanted to be clear. The center pin of the power input is and will always remain positive.

 

Unless you reverse the connections at the power supply outputs...

 

^Double reverese.