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B1 with Korg Triode
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Old 25th March 2020, 04:39 PM   #4551
Soundhappy is offline Soundhappy  France
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Extract about ground to chassis connection from great 6L6 build guide
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Old 25th March 2020, 05:19 PM   #4552
Hikari1 is offline Hikari1  United States
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Mine is not grounded (using plastic standoffs on PCB).

It is not noisy or anything but I am using a linear PSU. Is connecting the ground to chassis mandatory?
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Old 26th March 2020, 12:25 AM   #4553
itsikhefez is offline itsikhefez  United States
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B1 with Korg Triode
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Originally Posted by Soundhappy View Post
Any work in progress news ?
Use of vibrations damping material for relays and Nutube triode ( component only ) is a good idea
but B1K pcb need to be tighty connected with 4 metal standoffs, metal screws, metal washers ( without rubber or plastic )
to " naked " metal of the chassis box so ground path is OK.
Papa example preamp is always closed , two mono volume potentiometers.
Work like a charm source: B1 with Korg Triode
I'm still experimenting... I've ordered various types of dampening sheets to apply to the chassis covers, and to the relay strip and Nutube.
I also ordered some of those isolating standoffs Roo2 mentioned.

I can't fully close the chassis yet as I don't have panels, and a volumee display is held with zip ties to the frame which prevents closing the lid entirely.

I placed an order for front and rear panels for my chassis and external PSU, once I get those I will finalize the wiring and test with it fully closed.

The various methods I've used help reduce the ringing with volume change, I'm hoping the stuff that is on the way will eliminate it.
A loud clap can cause ringing, but I'm assuming that will be resolved once I'm able to totally close it.

Before ordering panels from FPE (I really like my projects to be aesthetically pleasing), I wanted to listen to this before investing further $$ into it. With my recently built F5 into PMC 87db standmounts, this is some of the best sound I've heard in my room.. definitely a keeper.

Regarding grounding, why do you need all 4 washers.. shouldn't a single connection be sufficient?
Right now, I only have one standoff that is fully metal-metal that is grounding the PCB to the case, the others are with rubber grommets for vibration control.
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Old 26th March 2020, 01:27 AM   #4554
Halauhula is offline Halauhula  United States
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If I want to use the Whammy headphone amp with the B1 Korg, and use 2 pots - one 50K pot for B1 Korg and the other for the Whammy, do I need to: (i) use a buffer before the two pots; or (ii) add a switch after the input selector to direct the source to either the B1 or the Whammy? I am concerned that the loading of the Whammy pot in parallel with the input to the B1 Korg will throw off the B1 Kong's input, as I understand that the 50K input pot speed for the B1 Korg is critical.
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Old 26th March 2020, 01:32 AM   #4555
6L6 is offline 6L6  United States
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B1 with Korg Triode
50k isn't critical for the B1, as the NuTube is buffered on the input and the output.

I'm not sure how you are going to hook it up... Can you expand a bit?
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Old 26th March 2020, 01:41 AM   #4556
Halauhula is offline Halauhula  United States
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Originally Posted by 6L6 View Post
50k isn't critical for the B1, as the NuTube is buffered on the input and the output.

I'm not sure how you are going to hook it up... Can you expand a bit?
Yes:

Inputs to source selector switch; then to both: (i) a 50K pot (actually, I will be using a TubeCAD S3 attenuator so I can avoid the pot slider and have integrated balance control) for the B1 Korg, which will then connect to the B1 Korg at the designated PCB pot connection points; and (ii) 20K pot for Whammy, which then will connect to Whammy at the designated PCB pot connection points.

I'm sure I read something that said the 50K pot was somehow critical to the proper functioning of the B1 Korg. Perhaps I am wrong. In which case, the lower impedance due to the paralleled pots should not be a problem (assuming the source can drive both pots). Some concern about this is why I would either switch the source to either the B1 Korg or the Whammy or use a buffer.
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Old 26th March 2020, 04:43 AM   #4557
itsikhefez is offline itsikhefez  United States
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I fired up my B1 for the first time and want to confirm the voltages. I'm using a regulated linear supply (AMB s11), and the output from that is 23.97V. The output on the s11 is determined by a Zener diode and a ratio of 2 resistors, so the tolerance of those 3 components will determine the end-result voltage.
With this, everything is pretty much up to spec except T3 which I have 22.44V.
Now, this does seem very marginal, but the guide says that values should fall within 0.5V, and in this case I'm slightly out of spec. I think the build is fine as all other test points are exact.

Would you leave this as-is, or perhaps try a slightly lower value resistor on the CRC to drop less voltage?
So something weird is going on... earlier, besides T3 being on the slightly low side, all the other voltages were spot on.
I haven't changed anything on the board itself, and now I have quite a few deviations.

First, it seems like my mains flucuates a bit, since now my PSU is outputting slightly more than before, a steady 24.11V.
T3 now measures withing spec at 22.7V.
BUT, T4 is now 11V (it was around 9.2V), which has a cascading effect that T6 and T5 are 0.9V.
T7 and T8 went down to 6.2V, they were at 9.6V beforehand.

Any ideas how this could have suddenly changed?
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Old 26th March 2020, 08:23 AM   #4558
Roo2 is offline Roo2  Australia
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My B1 Korg isn’t grounded over and above the 24vdc power supply to the board if that has any? The wall wart is only two pin (active and neutral). Perfect sound, no ringing.
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Old 26th March 2020, 08:06 PM   #4559
itsikhefez is offline itsikhefez  United States
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Originally Posted by itsikhefez View Post
T4 is now 11V (it was around 9.2V), which has a cascading effect that T6 and T5 are 0.9V.
T7 and T8 went down to 6.2V, they were at 9.6V beforehand.
Any ideas how this could have suddenly changed?
Regarding this, I pulled the 270R resistor and it is fine... so my only guess here is that the Zener diode is faulty. Is that a reasonable assumption or could there be a different reason?
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Old 26th March 2020, 08:11 PM   #4560
Hikari1 is offline Hikari1  United States
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Quote:
Originally Posted by itsikhefez View Post
Regarding this, I pulled the 270R resistor and it is fine... so my only guess here is that the Zener diode is faulty. Is that a reasonable assumption or could there be a different reason?
Is your regulator regulating? You need to measure the voltage at the output of the regulator to see if it is varying before assuming it's the B1 Korg.
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