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...12050QQcmdZViewItemQQ_trksidZp1742.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
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...12050QQcmdZViewItemQQ_trksidZp1742.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
kevinkr said:
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
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.
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.
Attachments
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.
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.
Which Pot?
Great that yours is working. Mine is also working, although a little more noise in one channel and of course the stupid blinking of one on the 6N3 driver blue tubes. I can buy another one at this price, anyway.
I found a tube that is american made and is identical to 6N3 except it is supposed to sound much better as a driver tube. They sell these for $7.95 a pair so you can't go wrong. Check Other Items and you will see different kinds. I like the military style tubes. =)
http://cgi.ebay.com/5670-5670W-2C51...5|66:2|65:12|39:1|240:1318|301:1|293:1|294:50
I also want to buy a pot, because a 30W preamp is L O U D. I wonder what kind? I saw a 50W L-pod potentiometer. Is this the right kind? I don't think a 0.02W 100kOhm guitar potentiometer will hold up for the job. Or will it?
Link: http://www.ljudia.se/tillbehor-s82136/potentiometer-c79649/l-pad-50-watt-p79647/
To stray off topic, I contacted Lundahl, since I live two hours drive from their HQ *proud*
, however they said they didn't have my kind of tranformer, sadly. I did however buy their Ribbon Microphone transformer for my DIY ribbon mic with really cool results. I will exchange the guitar magnets for Neodym magnets soon. Money saved! A proper ribbon microphone is expensive!
Great that yours is working. Mine is also working, although a little more noise in one channel and of course the stupid blinking of one on the 6N3 driver blue tubes. I can buy another one at this price, anyway.
I found a tube that is american made and is identical to 6N3 except it is supposed to sound much better as a driver tube. They sell these for $7.95 a pair so you can't go wrong. Check Other Items and you will see different kinds. I like the military style tubes. =)
http://cgi.ebay.com/5670-5670W-2C51...5|66:2|65:12|39:1|240:1318|301:1|293:1|294:50
I also want to buy a pot, because a 30W preamp is L O U D. I wonder what kind? I saw a 50W L-pod potentiometer. Is this the right kind? I don't think a 0.02W 100kOhm guitar potentiometer will hold up for the job. Or will it?
Link: http://www.ljudia.se/tillbehor-s82136/potentiometer-c79649/l-pad-50-watt-p79647/
To stray off topic, I contacted Lundahl, since I live two hours drive from their HQ *proud*
, however they said they didn't have my kind of tranformer, sadly. I did however buy their Ribbon Microphone transformer for my DIY ribbon mic with really cool results. I will exchange the guitar magnets for Neodym magnets soon. Money saved! A proper ribbon microphone is expensive!
This is what I had to do to make it into a micrphone preamp. First I use my rather weak but clean Studio Projects VTB-1 preamp to the microphone or guitar. That gives me a balanced XLR out and a unbalanced TS 1/4" signal. It has a tube, but just as an insert effect tube which is rubbish compared to the real thing.
My DIY tube preamp is unbalanced (as I most recently were told). To use not only the Gain control and High Pass Filter, but also the volume knob and meter on my studio projects preamp, I will have to connect the tip and ring together in a Neutrik TRS 1/4" connector. This is a special function for Studio Projects I guess.
My analog inputs on my Lynx L22,which has a softwar controlled +4dB and -10dB, are XLR. So I have to make an XLR unbalanced. Inside the XLR male which is going into my soundcard from the preamp I move the white cable to the red cable and link the place where the white cable were - to the ground.
On the three preamp audio inputs, ground is in the middle, right channel has both red and white, and Left the same from the other cable.
Done!
My DIY tube preamp is unbalanced (as I most recently were told). To use not only the Gain control and High Pass Filter, but also the volume knob and meter on my studio projects preamp, I will have to connect the tip and ring together in a Neutrik TRS 1/4" connector. This is a special function for Studio Projects I guess.
My analog inputs on my Lynx L22,which has a softwar controlled +4dB and -10dB, are XLR. So I have to make an XLR unbalanced. Inside the XLR male which is going into my soundcard from the preamp I move the white cable to the red cable and link the place where the white cable were - to the ground.
On the three preamp audio inputs, ground is in the middle, right channel has both red and white, and Left the same from the other cable.
Done!
Finally got it. Here's a Guide for n00bs.
I could not wait for an answer and tested the 100k 0.02W Alps stereo potentiometer ($15 in Norway) on the DIY tube amp output and as you said the hum disappeared. This is a really cool preamp. Before my sound was dull and uninspired and weak. It did not work to amplify it with software. Guitar Rig worked, but then it is not your signal any more, just a modelled sound. This preamp amplifies it so I can almost use it out of the box (though the preamp came in a letter). It even kicked some life into my ultracheap Alto mictube.
I am still worried than I should not use a hifi preamp desigend for amplifying signals to power amplifiers, and perhaps not the way I use it - as a mic amp, amping the signal from my weaker mic amp, see picture. I am afraid to burn my soundcard again if the signals does not match.
It preamplifies an unbalanced signal and the soundcard has a -10dB. It should be OK, but it amplifies with 30 W and that seems a lot. My 0.02W potentiometer har survived on the output so I guess those Watts are not in the audio signal. I know so little!
Do a search for "Pre-AMP Amplifier KIT Tube 6N3srpp good for DIY" on Ebay.com if anyone want to test it themselves.
Specs:
30W tube preamp
¤ $54 Chinese 180V-0-180V + 2 x 6V transformer (works ok, but there are better transformers).
¤ $30 prebuilt board with including two 6N3 tubes and one 6Z4 tube.
¤ Free shipping
Recommended: $15 Alps 50k or 100k stereo potentiometer RK18 at the output for reduced hum. See picture for wiring guide.
Temporary Link:
http://cgi.ebay.com/Pre-AMP-Amplifi...5|66:2|65:12|39:1|240:1318|301:1|293:1|294:50
Warning: You can die if you don't know what you are doing. High voltages and high currents. Be careful. I have heard that a tube preamp can store energy for hours. Though I was eager to test this I have not...
Hope this helps someone.
I could not wait for an answer and tested the 100k 0.02W Alps stereo potentiometer ($15 in Norway) on the DIY tube amp output and as you said the hum disappeared. This is a really cool preamp. Before my sound was dull and uninspired and weak. It did not work to amplify it with software. Guitar Rig worked, but then it is not your signal any more, just a modelled sound. This preamp amplifies it so I can almost use it out of the box (though the preamp came in a letter). It even kicked some life into my ultracheap Alto mictube.
I am still worried than I should not use a hifi preamp desigend for amplifying signals to power amplifiers, and perhaps not the way I use it - as a mic amp, amping the signal from my weaker mic amp, see picture. I am afraid to burn my soundcard again if the signals does not match.
It preamplifies an unbalanced signal and the soundcard has a -10dB. It should be OK, but it amplifies with 30 W and that seems a lot. My 0.02W potentiometer har survived on the output so I guess those Watts are not in the audio signal. I know so little!
Do a search for "Pre-AMP Amplifier KIT Tube 6N3srpp good for DIY" on Ebay.com if anyone want to test it themselves.
Specs:
30W tube preamp
¤ $54 Chinese 180V-0-180V + 2 x 6V transformer (works ok, but there are better transformers).
¤ $30 prebuilt board with including two 6N3 tubes and one 6Z4 tube.
¤ Free shipping
Recommended: $15 Alps 50k or 100k stereo potentiometer RK18 at the output for reduced hum. See picture for wiring guide.
Temporary Link:
http://cgi.ebay.com/Pre-AMP-Amplifi...5|66:2|65:12|39:1|240:1318|301:1|293:1|294:50
Warning: You can die if you don't know what you are doing. High voltages and high currents. Be careful. I have heard that a tube preamp can store energy for hours. Though I was eager to test this I have not...
Hope this helps someone.
Attachments
Blue tubes
Not sure that this blue light is real: I never met a tube which lights up in blue, but always red.
Maybe it's a "Photoshop" effect, or a blue LED placed somewhere under the tubes - as several years ago a blue LED seemed to improve the sound of a CD player, why not on a tube
Anyway, my 6N3 tube preamp (excellent sounding tube) is orange-red, as any tube on the (blue) earth...
For thye price, it worth to try it out, and if ever the tubes shine blue, buy some others!
- dan
Not sure that this blue light is real: I never met a tube which lights up in blue, but always red.
Maybe it's a "Photoshop" effect, or a blue LED placed somewhere under the tubes - as several years ago a blue LED seemed to improve the sound of a CD player, why not on a tube
Anyway, my 6N3 tube preamp (excellent sounding tube) is orange-red, as any tube on the (blue) earth...
For thye price, it worth to try it out, and if ever the tubes shine blue, buy some others!
- dan
These are just awesome little preamps. The green LED in the tubes is cheesy, but you ought to just chuck the tubes and put in something decent. I put a pair of Tung-Sol 2C51 tubes in there, and the little thing simply kicks one whole lot of ***. Mine is dead silent, there are no hum issues whatsoever, and it is an altogether satisfactory piece of audio gear. Just a ridiculously good value.
If you want features, forget it ... there's one input and one volume control. But if you want cryssssstal clear sound, I highly recommend it. Take care to set up the transformer correctly because it's all over if you wire it backwards and then plug it in.
If you want features, forget it ... there's one input and one volume control. But if you want cryssssstal clear sound, I highly recommend it. Take care to set up the transformer correctly because it's all over if you wire it backwards and then plug it in.
I just got something similar from Ebay and connected it up.
I was not going to connect it up to my main rig without a test... So the trusty garage hifi amp - NAD3020 was pressed into service. The NAD has a pre and pwer section and they are normally connected by a simple jumper. Off with the jumper and connecting up the tube pre...
Using a tuner as source. On it all goes. Hmm, nice and quite with no signal - no hum etc... on with the source - wow it plays and actually sounds better than the NAD pre... No too hard I hear you cry. Smoke and function/integration test done.
So, off to the music room and plug it in to the main system.
Again no noise when no signal.
Plays music. Let all the other valves warm up a bit.
Yes the pre tube do get hot as they should.
There's a rather irritating green led under each tube - spoils the tiny bit of warm glow there is...
Actually it sounds pretty amazing for what it is!
Some pics
More listening time.
Is it definitely worth spending money on better tubes?
I was not going to connect it up to my main rig without a test... So the trusty garage hifi amp - NAD3020 was pressed into service. The NAD has a pre and pwer section and they are normally connected by a simple jumper. Off with the jumper and connecting up the tube pre...
Using a tuner as source. On it all goes. Hmm, nice and quite with no signal - no hum etc... on with the source - wow it plays and actually sounds better than the NAD pre... No too hard I hear you cry. Smoke and function/integration test done.
So, off to the music room and plug it in to the main system.
Again no noise when no signal.
Plays music. Let all the other valves warm up a bit.
Yes the pre tube do get hot as they should.
There's a rather irritating green led under each tube - spoils the tiny bit of warm glow there is...
Actually it sounds pretty amazing for what it is!
Some pics
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An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
More listening time.
Is it definitely worth spending money on better tubes?
Last edited:
I had no problem disabling the cheesy green lights. You just have to gently stab the LEDs in the center of the tube sockets with a sharp object. Looks so, so much better with the warm natural glow of tubes (that being said, they really don't glow all that brightly in a preamp -- it's not like they are power tubes being cranked up!). (Also, while I could not perceive a difference, I'm told that having LEDs in a preamp is a terrible idea because they add noise. Whatever the case, the preamp is absolutely dead quiet ... you can't hear any hum or other noise no matter how far you turn the volume up.)
I'm not sure whether putting better tubes in there is really worth it. I spent $100 on a pair of NOS Tung-Sols, but being real, the difference is very slight. I am well familiar with changing out power tubes in guitar amps, and those can make a huge difference, but in an audio preamp I guess it's not nearly as critical.
All in all, a killer, killer deal if you can live without remote volume control!!!
A pic of mine is at: https://plus.google.com/u/0/photos/...ms/5793293577173464577?authkey=CIaY0aXXtsTLBQ
I'm not sure whether putting better tubes in there is really worth it. I spent $100 on a pair of NOS Tung-Sols, but being real, the difference is very slight. I am well familiar with changing out power tubes in guitar amps, and those can make a huge difference, but in an audio preamp I guess it's not nearly as critical.
All in all, a killer, killer deal if you can live without remote volume control!!!
A pic of mine is at: https://plus.google.com/u/0/photos/...ms/5793293577173464577?authkey=CIaY0aXXtsTLBQ
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