Voltage across R1L = 1.64V, R1R = 1.61V.
Voltages at all T1 - T8 are in reasonable ranges per original Pass PDF.
I'm attaching pictures of the nutube because I admit, I am not sure I know exactly what I am looking for. To me, it appears symmetrical. (I had to take the pictures anyway and send to my computer because my old eyes could never see that level of detail anymore...) Ears are still good though.
Thanks,
Voltages at all T1 - T8 are in reasonable ranges per original Pass PDF.
I'm attaching pictures of the nutube because I admit, I am not sure I know exactly what I am looking for. To me, it appears symmetrical. (I had to take the pictures anyway and send to my computer because my old eyes could never see that level of detail anymore...) Ears are still good though.
Thanks,
Attachments
All your voltages are in range, the Nutube lights up, all point to a working B1 Korg. Have you tried it with a different amplifier?
Or, instead of swapping amplifiers, at the B1 Korg output RCA jacks, swap the left and right cables to the amplifier. Does the left channel remain quiet? If it still does, go to the B1 Korg input RCA jacks and swap the left and right cables from the source. Does the left channel remain quiet?
Or, instead of swapping amplifiers, at the B1 Korg output RCA jacks, swap the left and right cables to the amplifier. Does the left channel remain quiet? If it still does, go to the B1 Korg input RCA jacks and swap the left and right cables from the source. Does the left channel remain quiet?
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yes. I swapped left / right inputs and problem stayed in the left. So, two good source channels. I swapped the output of the Korg/B1 and it switched speakers. So, still bad left Korg channel. I bypassed the korg all together into the amp and both channels from to the amp are fine. Therefore problem is still in the left channel of the Korg/B1.
BTW, the R1 voltages I stated above are for the input sections. The values on the outputs are R1L= -1.65V, R1R = -1.60V.
Humm.
BTW, the R1 voltages I stated above are for the input sections. The values on the outputs are R1L= -1.65V, R1R = -1.60V.
Humm.
T1 to T8 measure reasonable.
Voltage across R1 similar for both left and right channel input and output buffers.
Both channels of Nutube light up.
But no left channel output.
Please check the voltage at Q1 source/Q2 drain relative to Gnd. Voltage should be approximately 12V.
Also check soldering of input and output jacks.
Pictures showing the whole preamp may be helpful.
Voltage across R1 similar for both left and right channel input and output buffers.
Both channels of Nutube light up.
But no left channel output.
Please check the voltage at Q1 source/Q2 drain relative to Gnd. Voltage should be approximately 12V.
Also check soldering of input and output jacks.
Pictures showing the whole preamp may be helpful.
Attachments
Thanks guys. Something more to noodle. I've been poking around tracing the signal. I've got input signal in both channels through both inputs. ( Left, right in both input 1 and 2) through the selector switch to the input of the volume pot. However, the output of one of the channels from the pot to the input on the board is getting pulled down to ground. So, I jumped the known good input signal to the output of the volume pot/bad channel input and that signal also got pulled down to ground. That is as far as I got, then I needed to clean things up. Unfortunately, I am going out of town early tomorrow am. and will not get a chance to pick this back up for about a week. I will start next time looking at the voltage on Q1/Q2. Thanks for the help so far. Regards.
I'll give it a shot...
First - As designed, the B1K has 16dB of gain. When you say "buffer", what exactly do you mean, and what are you looking for? What other gear are you planning on using it with up to and including your speakers? What's your overall gain structure, and what do you want it to be? Others' experiences may not matter too much if our needs and preferences differ vastly from yours.
If you haven't already, I'd read the article linked below and the build guide.
https://www.firstwatt.com/pdf/art_diy_nutube_preamp.pdf
Separate from whether it's the choice you're looking for... here are a few of my thoughts.
The good - It's a lovely / fun circuit to build and play with. Not sure of your build experience, but with a full kit, you can likely have your project assembled in a relatively short time. There's very little to worry about if you follow the excellent build guide. Additionally, you can alter the harmonic distortion profile intentionally (if desired), which can be a ton of fun, and IMO a wonderful learning tool. Altering the harmonic distortion profile of pre-amps and amps is interesting (to me), but I didn't start messing with it until I had some basic gear to measure it.
The middle road - I tend to agree with Nelson's guidance that if you're going to play with the distortion characteristics in your chain, it's best to only do it once, and typically the power amplifier is the choice. If you're looking for a unity gain pre-amp, the B1 may be something to consider. To me, the B1K has a very different character to a 'standard' B1. B1 (to me) has some character, but it's far more "transparent" than a B1K. The B1K (IMO) has a much more distinct character. It's intentionally a tone machine, IMO. So, tl;dr - if you want the 'character' of this pre-amp to shine (in it's 'standard' settings), you'd likely want a very transparent amplifier, and/or an amplifier that doesn't have a distortion profile of "equal / opposite phase" that may cancel out the neatness of the B1K's character or an amp that literally further amplifies that character by adding more of the same to the mix. When added to a chain versus a B1 as an example, it's very likely going have an audible effect and insert its own character. Do you want that? Whether you like the effect is going to vastly depend on both your preferences and your other gear. My
Other things I'd consider - Mircrophonics can be, but aren't always an issue. A number of posts cover preventative measures. Durability / longevity of the NuTube can be, but rarely seems to be, an issue. I personally don't know if the issues others had with NuTubes failing were from build issues or defective NuTubes, but I'd read the thread as much as you can to learn some other builders' experience.
Either way, it's a super-fun project. If your budget allows, I'd recommend building it. As always my opinion differs from many others, but I hope that helps.
First - As designed, the B1K has 16dB of gain. When you say "buffer", what exactly do you mean, and what are you looking for? What other gear are you planning on using it with up to and including your speakers? What's your overall gain structure, and what do you want it to be? Others' experiences may not matter too much if our needs and preferences differ vastly from yours.
If you haven't already, I'd read the article linked below and the build guide.
https://www.firstwatt.com/pdf/art_diy_nutube_preamp.pdf
Separate from whether it's the choice you're looking for... here are a few of my thoughts.
The good - It's a lovely / fun circuit to build and play with. Not sure of your build experience, but with a full kit, you can likely have your project assembled in a relatively short time. There's very little to worry about if you follow the excellent build guide. Additionally, you can alter the harmonic distortion profile intentionally (if desired), which can be a ton of fun, and IMO a wonderful learning tool. Altering the harmonic distortion profile of pre-amps and amps is interesting (to me), but I didn't start messing with it until I had some basic gear to measure it.
The middle road - I tend to agree with Nelson's guidance that if you're going to play with the distortion characteristics in your chain, it's best to only do it once, and typically the power amplifier is the choice. If you're looking for a unity gain pre-amp, the B1 may be something to consider. To me, the B1K has a very different character to a 'standard' B1. B1 (to me) has some character, but it's far more "transparent" than a B1K. The B1K (IMO) has a much more distinct character. It's intentionally a tone machine, IMO. So, tl;dr - if you want the 'character' of this pre-amp to shine (in it's 'standard' settings), you'd likely want a very transparent amplifier, and/or an amplifier that doesn't have a distortion profile of "equal / opposite phase" that may cancel out the neatness of the B1K's character or an amp that literally further amplifies that character by adding more of the same to the mix. When added to a chain versus a B1 as an example, it's very likely going have an audible effect and insert its own character. Do you want that? Whether you like the effect is going to vastly depend on both your preferences and your other gear. My
Other things I'd consider - Mircrophonics can be, but aren't always an issue. A number of posts cover preventative measures. Durability / longevity of the NuTube can be, but rarely seems to be, an issue. I personally don't know if the issues others had with NuTubes failing were from build issues or defective NuTubes, but I'd read the thread as much as you can to learn some other builders' experience.
Either way, it's a super-fun project. If your budget allows, I'd recommend building it. As always my opinion differs from many others, but I hope that helps.
Well, i promised to tweak it, and then return with teh subjective results. 🙂👍
So, Tweak 1! And The results are is in: I think it is Looking damn good with them stainless steel bolts instead of the stock black bolts. Well, size M3-M4 is not really TRUE BOLTS but you get it🙂
The ringing issue. Fundamentally it is a weakness. No doubt, what so ever. But with the anti vibration countermeasures i have applied, this is not a problem. Unless i tap the Nutube itself with a pen.
Solution. Well? Do not tap it with a pen. 🙂🤚
So, Tweak 1! And The results are is in: I think it is Looking damn good with them stainless steel bolts instead of the stock black bolts. Well, size M3-M4 is not really TRUE BOLTS but you get it🙂
The ringing issue. Fundamentally it is a weakness. No doubt, what so ever. But with the anti vibration countermeasures i have applied, this is not a problem. Unless i tap the Nutube itself with a pen.
Solution. Well? Do not tap it with a pen. 🙂🤚
Attachments
I have been using my B1 Korg ( an early example) in a secondary system in the livingroom. It was wery sensitive in the begynning with regard to ringing. But it does not ring now and havent for a long time. I only dialed in a monerate amount of 2nd harmonic and it is a really great pre. Im using it in front of a modulus86 chip amp driving some Carlsson OA51 LE2. I recently tested my sons amp, which is a 12-14 years old plain hypex ucd400, before sending it abroad to him. The combination sounded great, detailed, rich sound, great 3d and soundstage depth. I almost sent him a newer hypex in stead, the Carlssons, ucd400 and the B1 korg where so good together.
@voxxonline - I hope it's within the rules... mods if not, please remove or move ... joy of building vs. want to try it???
https://www.diyaudio.com/community/threads/b1k-nutube-preamp.391642/
https://www.diyaudio.com/community/threads/b1k-nutube-preamp.391642/
OK, I'm back to this. Thanks for your patients. I checked the voltages on Q1/Q2 as Ben requested. 10.6V for all on both channels. So, I went back through what I know and I made a mistake in what I said previously in two areas. First is, even though I grounded the 332K resister at the bottom left of the board, (see attached) it was not +F, but close. Also, the channel that is not working is the right, not the left. I marked the spot where I grounded the circuit on both attachments on the left channel. So, why am I not getting an input signal coming out of the volume pot on the right channel to the board? Is the pot bad? Or is the signal being pulled down to ground somewhere? Thoughts before I start to desoldering things?
Attachments
Yay, I had a very similar problem in post #7067 but never got any feedback. Unfortunately, I am about 5000 miles from my preamp at the moment, so I am unable to look closely at it. When I initially built it all the test voltages were nominal and I really enjoyed it with an amp camp amp until it suddenly stopped.thank you!
I've flushed all joints and still... then I noticed that the faulty side of the tube has its thin microphonic noise wire broken on the outer side,
attaching a pic, is this it? F1 side
When I get home I will get a good light and some magnification to see if anything looks amiss. If it doesn't I will make a post with a picture and see if any of the sharp eyes here can see what might be amiss.
spamela,
From what I can gather:
-you had an accidental short of the power to the left channel.
-your right channel is not working, left channel is working.
-all left and right channel voltages are identical.
Was the preamp fully functional before the accidental short? Or did this occur during construction and the preamp had never been confirmed to have both channels working properly?
So it seems to me that the components on the circuit board are working properly. That leaves all of the wired connections and off-board components connected the circuit board to be investigated. RCA jacks, input selector, volume pot, and all of their wiring and connections need to be checked.
I wonder whether the short caused any damage since the short was at the left channel but the right channel is not working.
Please post pictures of your preamp. Include pictures of the whole preamp and input/output wiring, input selector, and volume pot.
From what I can gather:
-you had an accidental short of the power to the left channel.
-your right channel is not working, left channel is working.
-all left and right channel voltages are identical.
Was the preamp fully functional before the accidental short? Or did this occur during construction and the preamp had never been confirmed to have both channels working properly?
So it seems to me that the components on the circuit board are working properly. That leaves all of the wired connections and off-board components connected the circuit board to be investigated. RCA jacks, input selector, volume pot, and all of their wiring and connections need to be checked.
I wonder whether the short caused any damage since the short was at the left channel but the right channel is not working.
Please post pictures of your preamp. Include pictures of the whole preamp and input/output wiring, input selector, and volume pot.