Massdrop Cavalli Tube Hybrid Amp

As a follow up to my earlier post, Massdrop quickly got back to me after I emailed them today regarding my issues and have kindly offered to send me a new CTH! Now THAT is good customer service.

 

aaaaaaaaaaaaaaaaarrrrrrrrrrrrrrrrrrrrrrrrrrgggggggggggggggghhhhhhhhhhhhh!!!!

You sold it????!!!!
After all you went through to acquire this unicorn?

 

Luckbad be Luckbad...

 

Word, thanks. DAC is Modi Multibit, so on the darker side, and my HD800 have SDR and Anax mods put in. If I did go with the MCTH, I think I'd build an AMB sigma11 for an LPS. I would mostly be using it with the Atticus mostly, and people say the syngery between the two is spectacular so I'm not concerned with that, but I would like it to be enjoyable with the modded HD800.

Vali 2 is okay, and we'll see how I feel about it once the tube adapters come in, but I have mostly stopped listening to my headphones while my Crack is undergoing surgery (which I really need to finish, it's been like two months now).

 

Not because I wanted to or to replace it with something. My 16 year old car quit on me and my wife is wisely opposed to debt. I voluntarily sold a bunch of stuff so we could afford to replace the car.

I've been running on audio fumes for almost 2 months and couldn't stand being ampless any longer.

Losing the Liquid Crimson sucked. I really hope the Platinum with LPSU holds its own with the Crimson because I'll be able to gather the funds for it.

 

Sorry about your car. Hope you enjoy the new one.

Anyway, it's only an amp. You'll get a replacement later on.

 

Very sorry to hear about the transportation issues.

You need to change your moniker; your current one seems to be a self-fulfilling prophecy.

To @Luckbad the Liquid Crimson was his personal holy grail. They are not easy to come by.

 

Yesterday, I received a Philips ECC88 A-Frame construction (looks NOS), Herleen Holland. It should be the same tube as the Amperex Orange Label (if I'm not mistaken), as described earlier in this thread.

For the past 18 hours of so, I have been burning the tube in on MCTH and Vali 2. It has very strident treble, noticeable even on Vali 2. Does this settle down at all after a certain period of burn-in?

My initial thoughts are that the tube is very clear and forward, it seems like a good match for both MCTH and Vali 2. There is some lack of refinement / smoothness to the sound. I am hoping that this and the strident treble will diminish after further burn-in.

 

I’ve had good luck with the Harleen tubes, both a Phillips 6DJ8 and a Bugle Boy. Both were used, and the 6DJ8 seems to be a bit distorted in the treble on one channel. My hope is that a good cleaning of the pins will solve this. Otherwise, I think it just gave up the ghost. This is noted on high gain settings, but not low gain, and in both the Liquid Crimson and the Vali2. I would never call the Harleen tubes’ treble strident, at least from those amps.

Edit: I forgot I have also tried the Orange label Amperex Harleen tube. Same house sound. Amperex also made a 7308 in the USA. It is a bit less euphonic, but still, not strident.

 

Sorry to hear this @Luckbad. I was kind of along for the ride while you were finding your Crimson. I’m sorry it had to go. Mine stays, I’m done as far as the “main rig” goes. My faffing about will now be on low priced mid fi.

I haven’t heard the MDCTH yet, but I’m looking forward to it. Something I’ve noticed with the Eitr/Modi Multibit/Vali2 with a decent tube/ stack - if you took the “big rig” away, I’d miss it. But not nearly as much as one would think. I suspect the MDCTH is similar, or better in that respect. Low priced mid fi is very good these days.

 

I have both an orange label A-frame and a bugle boy, I wouldn't describe either as strident in the MCTH. Although the Seimens I have can sound that way on bad recordings.

 

I have several Siemens tubes. Actually some of the first tubes I had in my pre-amp closing in on 20 years. They can sound very balanced or somewhat bright or bad depending on the unit. Same type of thing I have experienced with the Genelex Gold Lion tubes. Particularly the 6922’s. Trial and error.

 

My Chinese LPS should be arriving within the hour. Do these power supplies general have built in over-current protection? Would momentarily shorting the +/- outputs be a good way to check if it does? I'd rather fry the LPS than the amp.

If not, would it be advisable to put a fuse inline? Which way to the audiophile fuse rabbit hole?

 

I would not short circuit the LPS unless I knew it had short circuit protection. You might needlessly destroy a perfectly fine unit. If you are experimenting, then a voltmeter should be mandatory to see if it puts out 28Vdc correctly.

 

OK. I reread the earlier discussions about overcurrent and inrush. I guess the worst that will happen is the LPS won't be able to provide the inrush current necessary when the MCTH is powered up, as @Bill-P found with his.

I was already planning on measuring the voltage output to make sure they sent me a 28VDC version.

Edit: And thanks Bob, for pointing out what a stupid idea that was . I'm a bit embarrassed, as I have a degree in physics, but don't seem to have retained a lot of practical knowledge (insert my avatar here).

 

@gixxerwimp - working around several thousand volts with 400 joule energy storage makes me very thoughtful. Usually one doesn't get a second chance. If you can, make a power cable with a tee so you can monitor the voltage while sequencing first the LPS followed by the MCTH. Watch what the voltmeter indicates during this staged power up sequence. There may be a slight dip in the reading when the MCTH is brought online.

I now have the LPS from @Bill-P for evaluation. I may not get to it for a week or two as I am about to take a major break.

 

Measured the voltage output while at work and they sent me a 110VAC in, 28VDC out power supply ... w00t!!!

The LPS was well packed, shipped out Sunday afternoon and arrived Tuesday morning, 20 min. before the estimated time of delivery given to me by SF Express tracking. Output was measured at 28.2VDC. I took apart the power supply end of the connector (see photo) and realized I could solder some wires on to measure the output voltage during the power up sequence as @atomicbob suggested. But then a wiser colleague said, "Why don't you just measure the voltage straight off the connector like that?" So that's what I did.



At home, I hooked everything up with the connector exposed and monitored the output voltage while I powered up the MCTH. The cheaper DMM I have at home needs to be on "high voltage" to measure 28VDC, so it only displays to the nearest volt. But it didn't dip below 28VDC during the MCTH's power up sequence and the LED turned from red to white as normal. Letting it warm up now before I do any listening.

This LPS from AliExpress was $90 + $18 express shipping to Taiwan. DHL to the US (6-13 days) is $33.61, which makes it a much better deal than $125 incl. free "economy international shipping" offered on eBay. There's a nice lady named Lisa who promptly answered all my follow-up questions sent through the AliExpress messaging system regarding the length of the included cable (1.2m) and when they would ship. This was my first time buying from them, and I was very pleased with the experienced. YMMV.

OK, I think I've killed enough time so that it's warm enough to have a listen.

 

Initial impressions (Pi Zero W w/ Volumio > Eitr > Modi Multibit > SYS > MCTH stock EH tube > HD650M):

The first few tracks in my test playlist don't have an emphasis on bass content, so I didn't notice that much difference at first. But on Get Lucky, the increased tightness and impact is obvious. Much of the woolliness is gone. On IM The Supervisor, there's a real visceral feel to the 1/4 note bass kicks and melodic bass line. When the 1/16 note bass pattern starts you can feel the difference even more. With the stock SMPS, you feel it around your collarbone. With the el cheapo LPS, it's closer to the sternum.

Going back to the stock PSU, it's like hitting a "soft bass" button. Songs without bass emphasis actually sound like they have a bit more bass, but I think it's due to the woolliness blurring what's there to make it sound like there's more. Switching back to the LPS, the bass tightens up and initial transient attack is more clear well-defined (not sure if this is finally figured out the right way to describe it).

I'm focusing on bass because that's where I'm looking for the most improvement, and it's easier for me to hear differences in that area. I might not even bother try to find improvements in other areas like clarity, detail and blackground (the latter is harder for me due differentiate due to tinnitus and traffic noise) - I'll just enjoy them if they're there. What I will do is compare bass performance with Magni 3 to see how close the LPS brings it.

It's late here so I'm calling it a night.

Edit: The MCTH was already warm, so I waited around 5 minutes after swapping between PSUs. Also, the first time I powered up the MCTH with the LPS, it seemed to take longer to do its startup sequence than with the stock PSU, but I put this down to the "anticipation time dilation effect". Just to be sure, I timed the sequence with the SMPS and it was 20 sec. Back to the LPS and it was 23 sec. I'll check it again next time I power it up and to see if it's consistent.

*a few more minor edits for clarity

 

I thought the idea of a socket saver was to have it inserted into the amp, and then plug the tube in and out of the saver, thereby saving wear and tear on the amp's socket. I bought some, but they aren't tall enough to be even flush with the chassis like @YtseJammer's.

When I go to pull the tube out the saver comes with it.
It's easier to get the tube in and out with the extra length providing more leverage to wiggle the tube from side to side. But is this the right way to use it?

I'd have to double stack 2 of them to get it high enough that I could hold it down and pull only the tube out. But that would add 2 more connections per pin, which can't be good.

 

The socket saver I'm using is like @YtseJammer's - the top surface of the saver is flush with the top surface of the CTH. When I change sockets I use a flat head screw driver or knife to hold down the saver when I pull the tube.

-----edit-------
But I'll be honest, now that I've found a tube pairing I like, I'm using the saver purely to raise the tube to make it more visible. I don't plan on changing the tube much going forward.