Need help with a Tube preamp Kit (6Z4, 6N3) - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 20th May 2008, 09:56 PM   #1
diyAudio Member
 
Alfetta87's Avatar
 
Join Date: May 2003
Location: Alsace
Unhappy Need help with a Tube preamp Kit (6Z4, 6N3)

Hi there,

I need some help, because I bought from eBay a complete cheap tube preamp, using russsian 6N3 tubes and a chinese 6Z4 rectifier tube.
Here is the seller's store, with the kit: http://cgi.ebay.com.my/IMPROVED-6N3-...742.m153.l1262

The attached schematic shows to use a 2x230V transformer, with a 0V middle point, to be connected to the ground (not shown on the schematic, but on the PCB).

When I switch it on, the transformer makes some noise, and the resistance RP (1k ohms, 3W) heats up to smoke, and of course I don't have the announced values of voltage.
I wonder what's wrong: the 6Z4 tube says performing up to 2 x 350 volts. See the attached PDF file.

Can somebody help, because the vendor seems to be set on "mute".

Thanks,
Dan
Attached Files
File Type: pdf 6z4.pdf (96.9 KB, 907 views)
__________________
It is worth to keep your mouth shut and let people think you’re stupid; rather than to open it and thus eliminate any doubts...
  Reply With Quote
Old 20th May 2008, 09:59 PM   #2
diyAudio Member
 
Alfetta87's Avatar
 
Join Date: May 2003
Location: Alsace
Default Need help with a Tube preamp Kit (6Z4, 6N3)

The kit says some 5670 tubes could be usec (same pin connection), but actually I installed the 6N3 - anyway, it smokes even without those tubes placed in the socket.

Attached the schematic, if the auction would end.
Attached Images
File Type: gif 6n3_preamp.gif (21.7 KB, 2214 views)
__________________
It is worth to keep your mouth shut and let people think you’re stupid; rather than to open it and thus eliminate any doubts...
  Reply With Quote
Old 20th May 2008, 11:03 PM   #3
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
I'd look for a shorted or miswired C7 and/or a shorted or miswired rectifier tube.
__________________
You might be screaming "No, no, no" and all they hear is "Who wants cake?" Let me tell you something: They all do. They all want cake.- Wilford Brimley
  Reply With Quote
Old 21st May 2008, 09:09 PM   #4
d2134 is offline d2134  Romania
diyAudio Member
 
Join Date: Mar 2007
Send a message via Yahoo to d2134
C6 is the first capacitor.
  Reply With Quote
Old 21st May 2008, 09:48 PM   #5
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Yes, C6 then. Thanks.
__________________
You might be screaming "No, no, no" and all they hear is "Who wants cake?" Let me tell you something: They all do. They all want cake.- Wilford Brimley
  Reply With Quote
Old 22nd May 2008, 05:04 PM   #6
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Hi Alfetta,
Your avatar is the Atomium in Brussels isn't it?

Check for backwards electrolytics at both C6 and C7. (Replace if backwards.)

Look for shorts on the B+ rail - do you have a dvm?
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 25th May 2008, 08:33 PM   #7
diyAudio Member
 
Alfetta87's Avatar
 
Join Date: May 2003
Location: Alsace
Default Need help with a Tube preamp Kit (6Z4, 6N3)

Quote:
Originally posted by kevinkr
Hi Alfetta,
Your avatar is the Atomium in Brussels isn't it?
Yes it is. Because I use to live in Brussels before moving to France. But since I'm not living in or even close to Paris, I'll not put the Eiffel tower... and there is nothing here in Saint Etienne what I could put as a picture!


To all who replied: C6, which has been taken from my box with hundreds of caps, had it's printing almost gone, and I switched plus and minus... shame on me!
Now it's working, at least all the voltages are OK, no smoke and nothing blown away.
This week I'll try the beast on my stereo set...

Thanks for the hints.

Cheers,
- dan
__________________
It is worth to keep your mouth shut and let people think you’re stupid; rather than to open it and thus eliminate any doubts...
  Reply With Quote
Old 21st April 2009, 01:59 PM   #8
Rewind is offline Rewind  Sweden
diyAudio Member
 
Join Date: Jan 2009
I have the "Pre-AMP Amplifier KIT Tube 2*6N3+6Z4 good for DIY"

Have you contacted the seller? He can supply you with a 180V-0-180V transformer. On mine the board says 230V-0-230V but that is way to much. Probably causing the smoking. Be careful. I fried my 700 dollar Lynx L22 soundcard when trying it out, the wrong way, presumably. I still get sound but the soundcard needs 80% on the left volume and 30% on the right channel to give a balanced left/right sound.

I think it happened when figuring out in what order of red white and ground I should have connected the cut XLR cables from the soundcard.

I hooked it up to the soundcard, recording guitar and vocals and I sounded like Elvis. I also used it as a preamp for my monitors. My Alesis M1 Active really came alive. Nick Drake sounds like I am in his bedroom. A proper tube amp can really be a time machine.

Now the only problem is that one of the blue tubes in the middle position is blinking, perhaps indicating something is a bit off.

Study my wiring in my photo and make a guess.
Attached Images
File Type: jpg dsc00017.jpg (77.3 KB, 1834 views)
  Reply With Quote
Old 21st April 2009, 02:50 PM   #9
diyAudio Member
 
Alfetta87's Avatar
 
Join Date: May 2003
Location: Alsace
Hi Rewind,

My preamp is complete on one board, rectifier tube, 6N3 tubes and filtacaps everything together.

As said in the thread previously, I made it work correctly, but had a lot of hum problems. I'm using 230-0-230V transformer, and it works fine.

I also had ground problem (causing some hum), now it's on a reasonable level - but still not totally gone.

So my solution is to put the volume pot at the output, then it drives a Luhndal transformer, and output is on XLR. Since the volume pot is always rather turned down, no hum.

Sound is fantastic, the 6N3 is a killer tube. I tried several commercial amps, and none of them could reach the sound quality of this little preamp.
__________________
It is worth to keep your mouth shut and let people think you’re stupid; rather than to open it and thus eliminate any doubts...
  Reply With Quote
Old 22nd April 2009, 09:04 AM   #10
Rewind is offline Rewind  Sweden
diyAudio Member
 
Join Date: Jan 2009
My picture by the way is wrong. So any builders out there, don't copy me. The seller first said it was balanced Line Level. In Chinese balanced must be unbalanced...
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
need diy tube preamp (line-stage) recommendation and general tube advice Musiclover4 Tubes / Valves 16 18th May 2013 03:19 PM
FA: Eico HF-85 Tube Preamp & HFT-90 Tube Tuner joe-electro Swap Meet 0 31st May 2009 04:14 PM
Tube Preamp Popping on Source Input Change (?) / 6DJ8 Preamp On Chip Amps MartyM Tubes / Valves 3 16th October 2008 04:52 AM
tube preamp using submini tube unclejed613 Tubes / Valves 11 19th August 2007 07:14 PM
Is it possible to get "tube sound" with just a tube preamp and chipamp output? Spasticteapot Instruments and Amps 43 15th May 2006 05:28 PM


New To Site? Need Help?

All times are GMT. The time now is 05:49 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2