• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

6J1 China preamp thoughts

Jump to Latest
Tony44

Tony44

Member
Joined 2014
hifix said:
Does anyone know how to reduce the gain from a fx audio tube 01 preamp ?
Its sounding quite nice, but i think (some say) its got 15db worth of gain. Anywhere from 6db to 0db would be nice.

6485700-5.jpg
Click to expand...
Please schematic for this audio hi-fi preamp...
Thanks,
 
Tony44

Tony44

Member
Joined 2014
demonmsk said:
As you know DC-DC converters are produce some interferes (RFI). Tube-01 have a DC-DC converter made as separate pcb. I did not have any problems with RFI from this pcb but I decided to do steel shield. And I made it from a steel shield, which I removed from an old printer. Very simple and I recommend this modding for all users.
Click to expand...
Please shematic with this the audio preamp?
Thanks,
 
Arthur Jackson

Arthur Jackson

Member
Joined 2014
6V6dude said:
I normally build high voltage tube preamps but couldn't resist trying the China 6J1 kit even tho I didn't expect much at all. There are few versions, I got the blue one in the pic here. I must say I'm quiet impressed with the sound, it is very clean, no top end loss (that I can hear), smooths out audio little (for a single stage) and can double the output so it's more than a buffer. It is useful little preamp.
But I'm running it at 16V because that's all I had and on the back of the board is printed plate Voltage 28V. I'm reading 38V. Either they made a mistake or maybe it sounds good because it's getting more Voltage. Yes I did drop the heater Voltage resistor to 6.3. Anyone build this thing? What plate Voltage do you get at 12V and what are general thoughts on these 6J1 buffers?
An externally hosted image should be here but it was not working when we last tested it.
Click to expand...
I made one just for giggles and ran it at 22V because that’s what I had. It sounded good except for a bit of hum that I couldn’t get rid of. Nothing seemed to work, not even chicken feet and voodoo. It started arcing and eventually went poof, too much juice I guess. Fun experiment but I don’t recommend them due to the hum. Mine had four tubes, the new ones on amazon have two. I might try one of the newer kits, you know, for giggles. It might work this time!
 
R

Raycarr00

Member
Joined 2013
there's a capacitor mod to rid it of hum in this thread. I experimented it to death and moved on to the fx version. there's a whole thread on it on audiokarma. the fx has smd components, though and not as fun to modify. the board is easily damaged, as well. the Chinese translations are not accurate- bile n fever; one might be tube and the other power. don't recall. it's hard to beat the 6j1 pre for sound and fun. it just has its limitations.
 
Wik

Wik

Member
Joined 2021
R

rss388

Member
Joined 2007
Actually, this comes from the use of online translators. In Chinese, the term for audiophile is someone who has fever for audio; the term for tubes translates to either pipe or gall bladder, due to the shapes. The advertisers use online translate tools and thereby getting these weird, out of context, terms. They must all use the same one too, as the tool somehow translates gall bladder the organ into bile the fluid and all of them say the same.
 
  • Like
Reactions: 1 users
acamus

acamus

Member
Joined 2014
Since my thoughts on 61J preamp will not fit into one post I have compiled a document,
It comprises $1 modification path in both Cathode follower (reaching THD: 0.009528%) and Common Cathode (reaching THD: 0.196589%) setups.
I have build both and they are working smoothly.
If you find my thoughts useful please consider buying me a beer for the dedicated free time in the span of 3 months, specially if you want to use my design for commercial purposes (yes, I mean you Chinese people too)
 

Attachments

  • 6J1 preamp thougths - 1$ mod.pdf
    4.5 MB · Views: 457
  • Like
Reactions: 1 users
Turbowatch2

Turbowatch2

Member
Joined 2013
I do not think of people you interact in China they sure are just as nice as any Russian. The whole Chinese economic wonder is build on copy and steal of interlectual property. This is not enough, international borders exist for Chinese only until they ignore them. South China sea? Taiwan? Covid? This is no friendly country, even as you may have some good pal's there.
 
jcalvarez

jcalvarez

Member
Joined 2021
Paid Member
It happens that my wife is half Ukrainian, half Russian, I went to university in Odessa, and worked in Russia for 6 years. I know what I'm talking about.
There are good people everywhere, and there are bad apples too.
Sorry for the rant, but I do not really enjoy blanket statements about countries and people.
To the OP, apologies for the off-topic.
 
  • Like
Reactions: 1 user
You must log in or register to reply here.
Top Bottom