It looks like your bias supply is working. I assume that G1 (bad channel) is at maximum, and yet the current and voltage drop across 332k plate resistor is low.
Another possible thing to check is make sure that all of the component leads on the underside of the PCB are short so that they do touch the chassis.
If all of the solder joints are good, all of the resistor values are good, and 24V is measured at the input (left side close to pcb edge) of the left channel 332k plate load resistor (full voltage is getting to the left channel of the NuTube), then I would say that there is a problem with the left channel of the NuTube itself.
Another possible thing to check is make sure that all of the component leads on the underside of the PCB are short so that they do touch the chassis.
If all of the solder joints are good, all of the resistor values are good, and 24V is measured at the input (left side close to pcb edge) of the left channel 332k plate load resistor (full voltage is getting to the left channel of the NuTube), then I would say that there is a problem with the left channel of the NuTube itself.
Voltage across the bottom left 3332K resistor close to the edge of the board is 20V on my multimeter, same as on the right channel.
I will get a second nutube and see the difference. If it turns out to be my bad soldering still, I will make a second B1 to give away as a gift.
Thank you Ben for your help. Very much appreciated 🙏
so there are three 332ks per side, one on the top, two on the bottom. the upper one of those on the bottom being closer to the edge on the left side. which is the one i measured?! i think we mean the same -_- thanks again
I worked with Ben before (he’s good) with almost a similar problem where I couldn’t get T7 and T8 to resolve below 15 or 16. volts by adjusting the 10k trim pots.
It was due to 6 resistors not being the the right value. Of course I sourced all the resistors (not the ones included with the matched Jfets) and misplaced a decimal point value.
Would it be advisable to pull all the resistors on the bad channel and ohm test them out of the board to make sure they read their stated values.
It was due to 6 resistors not being the the right value. Of course I sourced all the resistors (not the ones included with the matched Jfets) and misplaced a decimal point value.
Would it be advisable to pull all the resistors on the bad channel and ohm test them out of the board to make sure they read their stated values.
Thanks Benji, I was actually reading your conversation and trying to see how it applies to my problem. However, I checked all the resistors with a MM beforehand, and they are identical on both sides, so there problem can't be there really.
If not allready said, and all else fails to identify the problem: before pulling your Nutube, it might be worth performing a DMM beep test between the G1-2 legs and the next logical place on the PCB, following the traces from G1-2. the traces will end up @ a resistor or a cap or a JFET. Put one DMM probe on the G legs, one at a time, and the other on the first solder island/resistor leg etc along the PCB trace. If you don’t have a beep function, try measuring in Ohms. Good joints should provide a close to 0R reading. Bad ones, will perhaps show more or an unstable reading.
This can help narrow it down even further
regards
Andy
So continuity checks out on G1/G2 to the cap leg.
The 332k plate resistor checks out at 332k.
Re voltage, I think it is a combination of the power supply maybe being slightly less than 24V and my multimeter being somewhat inaccurate at the range just above 20V (it is switching ranges there, no extra digits).
From the power plug, it comes in at 23V, T1 is 23V, T2 is 22V, T3 22V.
Both at the 332k plate resistor and the 332k input buffer resistor it then measures 20V on both sides (now I got the distinction, thank you @Ben Mah). As I mentioned, all the voltages check out according to specc across both channels, up to T7...
Thank you both and kind regards,
jan
The 332k plate resistor checks out at 332k.
Re voltage, I think it is a combination of the power supply maybe being slightly less than 24V and my multimeter being somewhat inaccurate at the range just above 20V (it is switching ranges there, no extra digits).
From the power plug, it comes in at 23V, T1 is 23V, T2 is 22V, T3 22V.
Both at the 332k plate resistor and the 332k input buffer resistor it then measures 20V on both sides (now I got the distinction, thank you @Ben Mah). As I mentioned, all the voltages check out according to specc across both channels, up to T7...
Thank you both and kind regards,
jan
Hi sti571,
Is it possible you might have a lifted/broken PCB trace somewhere feeding T7 that is being over-looked?
Soldering and un-soldering can wreak havoc on the PCB traces.
Is it possible you might have a lifted/broken PCB trace somewhere feeding T7 that is being over-looked?
Soldering and un-soldering can wreak havoc on the PCB traces.
Hi Benjisan, no don't think theres the problem -_-. I ordered a second nutube and will report back. Thank you 🙏
Anyone used a B1 with a Pass Pearl 2 and/or Pass F6? Thinking of completing the Pass DIY chain!
My current setup is as follows
○ Anthony Gallo Subwoofer Amp ->
- Anthony Gallo Reference 3.1 speakers
wondering if the B1 at a gain of 6.3 (16dB) will be enough (????).
My current setup is as follows
- Systemdek IIX (Rega RB330 arm) with Sumiko Songbird MC cartridge (0.5mV) ->
- Pass Pearl 2 phono (55dB 562Av) ->
- 124B common cathode preamp (22dB 14Av) ->
○ Anthony Gallo Subwoofer Amp ->
- Anthony Gallo Reference 3.1 speakers
wondering if the B1 at a gain of 6.3 (16dB) will be enough (????).
Well,
I'm using this Korg B1 into a DIY F6, out to a pair of HSU horn-and-6"woofer based bookshelves and feeding a complimentary HSU powered sub. I haven't had the volume up to 12:00 noon yet in the month I've been running the combination.
Also, isn't there a review on Youtube with the F6 and the same Gallo speakers, but maybe without the Gallo sub amp?
I'm using this Korg B1 into a DIY F6, out to a pair of HSU horn-and-6"woofer based bookshelves and feeding a complimentary HSU powered sub. I haven't had the volume up to 12:00 noon yet in the month I've been running the combination.
Also, isn't there a review on Youtube with the F6 and the same Gallo speakers, but maybe without the Gallo sub amp?
Yes there is. And he loved it, and refused to return to Papa, so he bought it
The reviewer loved the mids and highs. A bit tame in the bass on those speakers, but the OP has as you say the solution for that with the Gallo woofer amp. In fact, I will not be surprised if the OP watched that specific Youtube review when contemplating his system.
The B1K will drive his F6 with it’s gain, so if volume becomes an issue he may have to rethink either amp or speakers, following Papas logic. I think it will work wonders, just do it, I say.
🤣🤣🤣The Pass DIY chain is never complete...
ok I am sold!
I know the F6/Gallos 3.1 review but I don't think I've seen the review with the B1K also at play. Anyone have a link to that?
The F6 with the Gallos 3.1 and the additional sub amp is indeed top notch!
Ok I pulled the trigger and got the B1K kit!
Going to read through the thread but from what I've gathered so far it seems like general mods/upgrades from the standard kit are:
What else am I missing???
Going to read through the thread but from what I've gathered so far it seems like general mods/upgrades from the standard kit are:
- linear 24V regulated PSU
- increased filtering on the onboard PSU
- "better" volume pot
- "better" gate stopper resistors
- "better" coupling caps
- "better" RCA jacks/shielded wiring
What else am I missing???
I question the better RCA jacks as the ones that come with the kit are already pretty nice. I am about to finish up a build with the Artemis single rail power supply:
https://www.audiosy.net/2021/03/17/first-look-artemis-single-rail-power-supply-rev-b/?amp=1
I've already listened to the preamp with upgraded coupling caps and that definitely did make a difference.
I will let you know what I hear, or at least what I think I hear with the upgraded power supply.
https://www.audiosy.net/2021/03/17/first-look-artemis-single-rail-power-supply-rev-b/?amp=1
I've already listened to the preamp with upgraded coupling caps and that definitely did make a difference.
I will let you know what I hear, or at least what I think I hear with the upgraded power supply.
I can report that the kit version sounds pretty marvelous as is 🙂
still, contemplating upgrades. But worth noting 🙂
