The Massdrop x Alex Cavalli Tube Hybrid: In With the New

The new Cavalli Tube Hybrid is an evolution of the original Compact Tube Hybrid DIY project.
The new “CTH” has significant improvements to the original design: Higher power output, approximately 1W into 50 ohms. The new CTH has some global negative feedback reducing the gain from the mu of the triode to a more manageable gain of 8x. By reducing the gain, we are able to make the amp work with the widest array of headphones through a very simple design to operate. The unity gain, discrete output buffers on the new CTH are updated versions of the buffers used in the Cavalli Audio Liquid Glass amplifier and provide the same or better performance.


The original CTH used a 24VAC wall wart power supply. This is suitable for a DIY project, but this type of power supply is uncommon and introduces raw power line AC and rectifier noise into the power supply circuit and the amp. The new CTH uses a 28VDC external power supply which is quieter than the original 24VAC supply. The power supply has no rectifier noise at 120Hz. The power supply also handles universal voltage (100-240V) for a single power supply version (use with plug adapters for your country if needed).
Anything the same? The original CTH has an auto-bias adjustment circuit on the tube so that no manual adjustments are needed. The new CTH does too.
PLEASE NOTE: The original CTH was designed to roll many different types of tubes. The new CTH is designed around the 6922 for simplicity of use. Owners can roll different types of 6922 or equivalent tubes, but they cannot roll other tube types into this new amp.

You’ll hear the differences in the new Massdrop x Cavalli Tube Hybrid.
Quieter, more powerful, easier to operate, higher resolution while maintaining that touch of tube warmth.

Massdrop 101: What Is An Amp?
Massdrop 101: What Is A DAC?

Feb 9, 2020
Just below this there is a review by Array1138 that I agree with entirely which made me want to post this. As I type, I'm listening to Pat Metheny through a pair of active Mackie hr624 speakers run from the output of a Cavali CTH. The sound is stunning in ways I took for granted until just recently when I had the Cavlli out of the mix for a brief spell. The Cavalli pairs with the Mackies so well as a sort of pre-amp with master volume that I started searching online to see if anyone else was using the amp in this way. That's how I found Array's post, and why I thought I'd say a little more about this use case. I use the Mackies in a smallish bedroom purely as listening speakers and not as Monitors. The 624s, like the 824s, have great built in filtering and attenuating switches to help tailor the sound to a difficult listening environment. With smaller bass drivers, the 624s are a great choice for smaller rooms particularly given how affordable these are on the 2nd hand market. Anyway, to focus more on the CTH, since first receiving it about a year ago I've had it setup in this bedroom as a headphone amp and easy to reach master volume for the Mackies. A few weeks ago I finally received a THX 789, and I was eager to compare the two amps. When it came to headphone listening, it was no contest. The 789 performed like a fighter jet, and the Cavali was like a comfortable bicycle. I was floored by how much of massive leap up in quality I enjoyed from a pair of 6xx headphones in particular. Mid range syrup, slowed transients and mud in the low mids present on the Cavali were banished by the 789. Shockingly the 6xx started to sound fast and precise, not that far off from planars in the bass region, again without some of the low-mid bump that is often associated with the 6xx (650), and so shouldn't be thought of as strictly emanating from the CTH. Rather the CTH didn't tame this. Next up it was time to plug in the Mackies. There I found the matter utterly reversed. For the first time I started hearing the Mackies as the supremely flat monitor speakers they were intended to be. The only thing is, they sounded like ... well I don't want to set off a debate about recording gear. I'll just say when I replicated the configuration I had setup with the Cavali, routing output from the 789 to the Mackies to use that amp as a master volume, the Mackies didn't sound like the sorts of monitors that would be my personal choice for recording (I've done my share). Then again, I should note I have them setup for casual listening in a bedroom, and it could be that properly positioning them for monitoring would take them to another level. So with the caveat my negative comments about their sound through the 789 doesn't necessarily accurately reflect the true potential of the Mackies, I found them to sound clinical, exactly as monitors should sound, but lacking in imaging characteristics. Clinical but bland. The difference was subtle but very substantial. I was extremely surprised. I picked up the Mackies for casual listening after receiving the Cavali, and had never listened to them without the Cavali in the Mix. For months after getting them I was floored by what underrated gems I thought the Mackies were and how fantastic they sounded. Low and behold it turns out the sound I was adoring was deeply indebted to the touch of tube harmonics being imparted by the Cavali. The CTH, it turns out, was a magical ingredient transforming their presentation from flat, but in a somewhat limp kind of way, to something lush, euphonic and addictive. So now I have a little stack in my bedroom and am making effective use of the RCA pass through on the 789. I use the CTH just as a tube pre for my active Mackie 624s and I'm so impressed by the combination that I went searching online to see if anyone else has written about this. Would I recommend the expenditure to transform a pair of active monitors from soulless to fun and lush? Yes. I think the transformation of the Mackie's into supremely enjoyable listening speakers is very noticeable and well worth the investment. My experience is the tube harmonics do wonderful, wonderful things to the depth of the soundstage in the stereo image for these active speakers. The combination of the flat monitor response and solid state character of the CTH keep things from getting out of hand and becoming unresolving. Instead the transformation is from clinical and dry to utterly fun and engaging while still being tight and clear. As per Array1138's post, it sounds as though this is an experience that can be repeated. I enjoy the results enough I wanted to share the findings along for others who might be interested in bringing a bit of fun and delight to an active monitoring setup. It's certainly a whole heck of a lot cheaper than investing in another pair of speakers.
Jan 15, 2019
It works very well as a preamp using the 4 pin out to a pair of Mackie HR824 MK1's. more musical with NOS 7308's, and more detailed with Sovtek 6922's, it replaced my Musical Fidelity X-Can V8P, which uses two 7308's and now I'm Shopping for a Schiit Valhalla 2 in order to try an OTL amp for the first time. The best thing about these new amps is their affordability. LOL
Oct 27, 2017
It would be great to see a version of this product with Balanced XLR outputs for use with monitor speakers. Any chance of that happening?
Hello. I have my CTH on order :-) My favourite tube in my current amp is an E288CC. I understand from the above description that the CTH is designed only for 6922 (E88CC) and equivalent tubes. The E288CC, strictly speaking, isn't equivalent to the E88CC (for example, it requires 475mA heater current as opposed to 300mA for the E88CC) but it is often used as a drop-in replacement. What I would like to know is the E288CC compatible with the CTH (I would not want to damage the amp)? Many thanks for your time. Looking forward to February 2018!
Dec 10, 2018
I haven’t... is it a viable option?
Dec 10, 2018
It would be if the filament power supply can handle it; 0.6A @ 6.3V. I popped the question to Cee-Tee and never heard back. I don't own a CTH, as an owner you could perhaps better elicit a response.
Aug 14, 2017
I own Fostex and HIFIMAN headphones. Can someone explain why I would need an amp? My volume output out of my PC is more than adequate--more than I could even handle in fact.
Aug 17, 2017
hello sir - so far I have had very good exeprience with AudioGD. The shipping was a bit slow (4weeks) but my unit arrived in the US safely (no dents on the box, no scratches on the unit). The build quality is superb. All the buttons have smooth movment, the volume knob is nice and heavy, the amp itself is pretty well constructed. The input / output connectors are pretty soild. My Amp came with a nice silver remote, and I use mine with headphones and a speaker amp (pre-amp to control volume) - Its a very powerful amp delivering 9900mw @ 16 ohms via XLR, and 3500mw @ 16 ohms single ended. It has no channel imbalance. I am quite happy with it :)
Apr 24, 2018
see I'm in a weird state with cables, because my logical brain wants to tell me no there is no difference, yet when i tried different cables on my hd600 i could definitely notice a difference, mainly in the presence area, one cable seem to have a more forward upper mid range than the other cable which actually made the hd600s sound worse than with the stock cable. but again without being able to blind test this, im kind of skeptical as to whether i heard a difference.
Aug 14, 2017
I'm really interested...but am also quite dubious when sellers highlight the words "entry level". I also feel weird about the words "entry level end game". Why under-sell, or under-value a product before it is even for sale? The sellers confidence in the product seems low.
Aug 28, 2017
If you have enough confidence to say End game w/ Entry level, that says something. End game is the best you will ever need for entry level? I guess if you want advanced you should think of spending more?
Aug 28, 2017
Sorry, I don't understand your questions. Maybe rephrase them
Aug 14, 2017
THIS IS A HYBRID DUE TO THE COMBO OF BOTH TUBE- & CLASS A(A/B?) POWER. THIS IS OBVIOUSLY 100% BALANCED, DUE TO THE FACT THAT THE ONE &ONLY OUTPUT I am ABLE TO SEE IS A 4-PIN XLR (never heard rumours about unbalanced 4-pin xlr outputs - It´s the new high-end balanced output because you don´t need TWO 3-pin xlr outputs. Finally but last.
Aug 14, 2017
You didn't see the 6.3mm socket next to it?
Aug 15, 2017
Your post couldn't be more naive or wrong in this case unfortunately. Read the specs, please. It is SE only, 2 of the 4 pins are to ground. There is no balanced input, so even if it was push-pull it wouldn't be balanced because the entire chain needs to be differential, from a balanced DAC chip onward.
Besides that fact, the included tube is a 2 cathode, 2 grid, 2 plate tube, meaning it can handle up to two independent channels. A balanced amp needs 4.
Aug 13, 2017
It has a little R2 unit on board.
Apr 24, 2018
haha it really does look like theres a mini R2D2 sitting in your amp xD
I'm not familiar with the old DIY versions topology/design. Is the power delivery rating the same for XLR output vs TRS? It's obviously not fully balanced due to the lack of associated inputs but was curious about more detail on the power delivery.
Aug 14, 2017
no - the XLR is single ended, no double voltage
Aug 13, 2017
Why is this hybrid? is it transister out with tube pre amp ?
Aug 15, 2017
My guess is two output stages.
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