Massdrop x Alex Cavalli Tube Hybrid Amp (CTH) - Dropping Monday
Sep 16, 2019 at 11:50 AM Post #1,143 of 1,397

PaganDL

Headphoneus Supremus
Joined
Feb 1, 2016
Posts
2,466
Likes
763
Hey guys,

I just acquired a 2nd hand massdrop CTH amp an am experiencing an issue where when playing music, I will suddenly hear a loud pop from the left channel. The light turns red and the music gets muted. Music resumes after a while, but this happens every 2-3mins. The problem occurs with and without headphones plugged in, with and without input plugged in, with different tubes and with different volume positions. Has anybody experienced this before? What could the problem be?

Really appreciate your help!

Thanks,
Kev


I have this issue as well. I just ordered a new Gold Lion tube to see if maybe that fixes the issue, but has anyone else here found a fix to the pop-shut off problem?


Just wondering if you both are still having issues with the CTH, hard to say exactly what is wrong exactly without seeing the board when the pop occurs but more than likely tube isn't quite fully seated in its socket.
Important thing to note whenever using a tube amp is the following :

1. Tube must to be fully seated firmly in its socket with no play in said socket,

2. Tube should be a perfect 90 degrees in said socket.
Amp cover should be perfectly level, only top tube half should be exposed.

3. Does the tube give a steady orange glow or is it flickering &/or blue in colour?
If flickering &/or blue in colour, then tube is definitely faulty, blue means tube has a minute crack somewhere with air leaking in, this is technically bad.

4. Are any pins bent or not the same length, if so, can said pins be straighten, if so, dedicated tube straighteners exist, if pins not the same length, this is creating all manner of electrical shorts which damage both tube and amp.

Hope this makes sense.

Hope you both have a great day !
 
Sep 16, 2019 at 4:15 PM Post #1,144 of 1,397

Zachik

Sponsor: Etymotic, Westone Audio
...is also a Hardcore Head-Fi'er.... I guess....
Joined
Jan 15, 2015
Posts
5,785
Likes
8,692
My last move will be an airist dac as well.
You'll absolutely love it - sounds great, and I love the stack :)
Currently, my Drop Stack is 3-high: LCX, RDAC, CTH. Both amps are fed by RDAC. One of the best bang-for-the-buck in the market.
 
Sep 16, 2019 at 5:38 PM Post #1,145 of 1,397

Guidostrunk

Headphoneus Supremus
Joined
Dec 30, 2009
Posts
4,992
Likes
4,019
Location
Pittsburgh, Pa
Ok folks. So once again , I played guinea pig with this amp. Now.........! I have to stress this first before I explain. I'M USING AN ACOPIAN A28MT300 EXTERNAL LINEAR POWER SUPPLY! It's 28v/3amp. I do not recommend doing this with your walwart!
So...... I bought a 6sn7 to 6922 adapter and a Tung-sol 6sn7gtb. This tube runs at 600ma. It's double the 6922.

I've been burning the 6sn7 tube in since this morning. Just got home from work and had a quick listen. All I can say is WOW!!!!!
Just when I thought it couldn't get any better. Sheesh!
My reason for doing it is:
1) I saw in a few comments on YouTube that someone was using 6cg7. Which is basically identical to 6sn7, but with the same pin out as the 6922.
2) I'm going to be listening to a Lyr3 next week. Lol.

I'll report back in a few hours after I get settled in and have a good listen to some familiar tracks. I have no issues whatsoever with the 6sn7 running in the amp. It's been in there since around 6am est.
I know 100% that I will never part with this amp now!
:beerchug:
 
Sep 16, 2019 at 6:08 PM Post #1,146 of 1,397

ls13coco

100+ Head-Fier
Joined
Nov 23, 2016
Posts
371
Likes
154
Location
BC, Canada
Ok folks. So once again , I played guinea pig with this amp. Now.........! I have to stress this first before I explain. I'M USING AN ACOPIAN A28MT300 EXTERNAL LINEAR POWER SUPPLY! It's 28v/3amp. I do not recommend doing this with your walwart!
So...... I bought a 6sn7 to 6922 adapter and a Tung-sol 6sn7gtb. This tube runs at 600ma. It's double the 6922.

I've been burning the 6sn7 tube in since this morning. Just got home from work and had a quick listen. All I can say is WOW!!!!!
Just when I thought it couldn't get any better. Sheesh!
My reason for doing it is:
1) I saw in a few comments on YouTube that someone was using 6cg7. Which is basically identical to 6sn7, but with the same pin out as the 6922.
2) I'm going to be listening to a Lyr3 next week. Lol.

I'll report back in a few hours after I get settled in and have a good listen to some familiar tracks. I have no issues whatsoever with the 6sn7 running in the amp. It's been in there since around 6am est.
I know 100% that I will never part with this amp now!
:beerchug:

Very cool, I look forward to hearing further impressions! Which 6sn7 tube are you using?
 
Sep 16, 2019 at 8:22 PM Post #1,147 of 1,397

Guidostrunk

Headphoneus Supremus
Joined
Dec 30, 2009
Posts
4,992
Likes
4,019
Location
Pittsburgh, Pa
A 1953 Tung-sol , tall bottle D getter.
20190916_201912-1-1.jpg

Very cool, I look forward to hearing further impressions! Which 6sn7 tube are you using?
 
Sep 16, 2019 at 9:02 PM Post #1,148 of 1,397

jasonho

100+ Head-Fier
Joined
Jun 2, 2012
Posts
348
Likes
429
Location
Singapore
Just wondering if you both are still having issues with the CTH, hard to say exactly what is wrong exactly without seeing the board when the pop occurs but more than likely tube isn't quite fully seated in its socket.
Important thing to note whenever using a tube amp is the following :

1. Tube must to be fully seated firmly in its socket with no play in said socket,

2. Tube should be a perfect 90 degrees in said socket.
Amp cover should be perfectly level, only top tube half should be exposed.

3. Does the tube give a steady orange glow or is it flickering &/or blue in colour?
If flickering &/or blue in colour, then tube is definitely faulty, blue means tube has a minute crack somewhere with air leaking in, this is technically bad.

4. Are any pins bent or not the same length, if so, can said pins be straighten, if so, dedicated tube straighteners exist, if pins not the same length, this is creating all manner of electrical shorts which damage both tube and amp.

Hope this makes sense.

Hope you both have a great day !

I encountered similar issue and it comes down to the LPS unit I was using connecting to CTH. Once removed, the issue went away. So in short, do check your power cable, lines etc..
 
Sep 16, 2019 at 9:58 PM Post #1,149 of 1,397

jrhill

Head-Fier
Joined
Apr 21, 2007
Posts
70
Likes
20
Location
Melbourne, Australia
I found a bit of a problem with the 6c8g tube sitting hard on top of the case without full pin insertion in the adapter socket (6922 ->6c8g socket) so I disassembled the unit and enlarged the hole on top to 38mm (1.5") then added a 'tube-guard' (I think it's for the kt88 tubes) and this enlarged hole allows full insertion - also added some 'liquid carbon' contact 'goo' from Mad Scientist (New Zealand) that seemed to add some extra clarity to the sound.
I tried a couple of linear power supplies and settled on the AMB Sigma 11 version (china version = S11)
The TungSol 6c8g is noticeably clearer in the mids than the KenRad 6c8g and does sound more relaxed that the Siemens PCC88 altho a rather good sound indeed.
I prefer this amp with it's upgrades to the Cavalli Liquid Carbon for it's musical sound (comes to about the same cost of the LC with the upgrades)

I use the Ayre Acoustic QB-9 dac for the source and ViaBlue cables so it's a rather good signal quality - my main headphones are the HE-500's but similar results on both the Senn 650s and curiously, the k-701 and 702s (all modded, of course!)

My main reference is the Ayre Codex headlamp/preamp so there's a big difference in the sound, yet the modded CTH doesn't disgrace itself in comparison, just different.

It'll be interesting to see if the extra heater current demand of the 6SN7 causes problems with the amp but the conservative designs of the Cavalli gear could have the Massdrop version to handle this quite well.

I'm also into amp/speaker/room acoustics but it gets exhausting to have so much response quoting the measured figures and 'gospel belief in that significance that it's such a relief to pop in here to get actual listening responses. [Mind you, I don't decry the use of the measured figures at all, just this weird belief that it somehow connects to what you actually hear]

Regards to all here ...
 
Sep 16, 2019 at 10:36 PM Post #1,150 of 1,397

Guidostrunk

Headphoneus Supremus
Joined
Dec 30, 2009
Posts
4,992
Likes
4,019
Location
Pittsburgh, Pa
I'm 3 hours in with the 6sn7. A whole new level of W.T.F? LOL! The transparency is ridiculous! The imaging is exactly how I remember the Woo Wa6, BH-Crack sounding. Soundstage is through the roof! It absolutely beats the 6c8g , in every aspect ; height, width, and most importantly, the depth! Extremely holographic!
 
Sep 16, 2019 at 11:41 PM Post #1,151 of 1,397

Kevin Tam

100+ Head-Fier
Joined
Sep 25, 2016
Posts
170
Likes
14
Location
Hong Kong
I'm 3 hours in with the 6sn7. A whole new level of W.T.F? LOL! The transparency is ridiculous! The imaging is exactly how I remember the Woo Wa6, BH-Crack sounding. Soundstage is through the roof! It absolutely beats the 6c8g , in every aspect ; height, width, and most importantly, the depth! Extremely holographic!

As exciting as this sounds, I am worried that you might be overloading the amp, especially since the tube heater does not support the high 0.6A current draw from the 6SN7 tube. Your adapter serves as a pinout converter. Not a current limiter.
 
Sep 17, 2019 at 12:56 AM Post #1,152 of 1,397

BrokeSkoolBoi

100+ Head-Fier
Joined
Dec 12, 2017
Posts
385
Likes
92
Location
VA/Miami
I hope your amp and your audio gear don't catch fire Guido! Has anyone tried this Telefunken Black Diamond E88CC tube https://www.tubedepot.com/products/telefunken-black-diamond-e88cc-6922 ?

I was getting grumpy about my SU-8 tonight so I took out my Electro Harmonix and rolled a Mullard I bought used on tctubes and the sound is definitely more tube like and I can't hear what i was complaining about before. It's not the clearest tube, it's slightly fuzzy. But, it is euphoric and warm without getting overbearingly so like my Amperex orange globe. However the higher frequencies aren't as forward which isn't great for everything

Edit: To answer my own question and anyone that happens upon this thread, I haven't found any fond reviews of the E88CC Telefunken
 
Last edited:
Sep 17, 2019 at 6:32 AM Post #1,153 of 1,397

Guidostrunk

Headphoneus Supremus
Joined
Dec 30, 2009
Posts
4,992
Likes
4,019
Location
Pittsburgh, Pa
If I was using the walwart, I'd be concerned. I'm well aware of what an adapter does. Lol
As exciting as this sounds, I am worried that you might be overloading the amp, especially since the tube heater does not support the high 0.6A current draw from the 6SN7 tube. Your adapter serves as a pinout converter. Not a current limiter.
 
Sep 17, 2019 at 10:00 AM Post #1,154 of 1,397

Phantaminum

Headphoneus Supremus
Joined
Mar 9, 2017
Posts
1,656
Likes
1,328
Location
Irving, TX
I'm 3 hours in with the 6sn7. A whole new level of W.T.F? LOL! The transparency is ridiculous! The imaging is exactly how I remember the Woo Wa6, BH-Crack sounding. Soundstage is through the roof! It absolutely beats the 6c8g , in every aspect ; height, width, and most importantly, the depth! Extremely holographic!

The 6SN7 is a beautiful sounding tube but you’re going to fry your amp. It pulls double the amount of amps that a 6922/E88CC/6c8g pulls. A Lyr 3 or other tube amps provides the right amperage for the 6SN7s. You may not see the immediate consequences now but slowly you’ll burn it out.
 
Sep 17, 2019 at 1:23 PM Post #1,155 of 1,397

Guidostrunk

Headphoneus Supremus
Joined
Dec 30, 2009
Posts
4,992
Likes
4,019
Location
Pittsburgh, Pa
The 6cg7 is a 600ma tube as well, and there's a person that's been using it since May and so far , no issues with the amp. He's using a beefier external LPS as well. So I'm assuming it's the LPS that's making it happen. Only time will tell. I'll report back in a week with an update on my progress. Maybe @CEE TEE can chime in and let me know what to check internally with a multimeter to see if it's biasing properly.
Edit: for the record. My LPS has 3amps to spare. Not 1.25 like the walwart.
 
Last edited:

Users who are viewing this thread

Top