On the Firstwatt website, Nelson recommends using a 1M ohm resistor across each RCA input to prevent "noise" while switching inputs. See the article for Korg preamp revised. I installed them on my build and have no noise issue switching inputs.
Left / Right channel - significant difference in volume
Hi all,
hope somebody can help. I'm measuring 8Vpp on the left and 2.5Vpp on the right channel output.
If I measure R anode I measure 300~ kohms on the left channel and 1.5 kohms on the right, quieter channel.
Is my 6p1 defective?
Thank you in advance.
Hi all,
hope somebody can help. I'm measuring 8Vpp on the left and 2.5Vpp on the right channel output.
If I measure R anode I measure 300~ kohms on the left channel and 1.5 kohms on the right, quieter channel.
Is my 6p1 defective?
Thank you in advance.
My Korg B1 using the DIY Audio external wall wart power supply is still sensitive to placement of other mains carying cables near it. I think you need to re-position the two boards as far from each other as possible in the case then put a shield over the power supply or at least a vertical barrier. Very nice looking case though.
Verify two 33.2K resistors soldering joints pads between two trimmers but from top up side of the pcb and 475R as well.
If need clean and reflow..is work better now ?
@soundwavesteve
As elwood625 suggests, grounding protocol is important to eliminate hum. Here's what I did following Nelson's advice and including the 1Mohm resistors to eliminate switching transients:
As elwood625 suggests, grounding protocol is important to eliminate hum. Here's what I did following Nelson's advice and including the 1Mohm resistors to eliminate switching transients:
What is important also is to ensure the chassis parts has electrical connection. I should "work" the screws a lot before this happened using same kind of chassis for BA-3 pre. The signal ground gets chassis contact via the four mounting screws so these should be checked also and then there should be no additional signal ground grounding.
@soundwavesteve
As elwood625 suggests, grounding protocol is important to eliminate hum. Here's what I did following Nelson's advice and including the 1Mohm resistors to eliminate switching transients:
Good point WKCox
First Watt wires are not stranded together but in paralell
Attachments
Soundhappy, thanks for your help. The 33k and the 475 resistors are ok. I think I have destroyed Q1 on the louder side somehow. This would explain that I measure the full 333k on the anode.
The FW layout is so clever made so distance is very short so twist makes no sense. I think if distance is long is makes sense to twist signal/ground wire?
If not.....I am confused…….
If not.....I am confused…….
Try it both ways and see whether you detect any difference, either by listening or measuring.
I did not run ground wires from input jacks to input selector so no twisting. Single ground from input/output jacks to main board so no ground loops. Inside of Kong triode case is a “clean” environment: no AC, no RF, no switching power supply, no digital, etc., so little need for shielding. Unit is absolutely quiet.
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An update on my unit: Hum problem solved. I tried grouping all of the RCA grounds together as suggested but it made no difference so that was not the problem. However that did lead me to discover that my chassis to system ground did not have continuity. The MeanWell PS I am using has one corner for its ground so I connected everything to it because it was in the most convenient spot for my wiring. Since the case is completely anodized and the PS is sitting on nylon standoffs and the mounting screw is sitting on top of the PCB, there was nothing connecting the case itself to the rest of my grounds. A resister lead fixed that and the hum is completely gone. I do hear the slightest bit of noise/hum with my ear against the speaker but a foot away and its gone. I still need to attach 1M resisters to the RCA jacks, I now know I need that after playing with the selector switch while testing. (covers ears).
There's no Covers Ears smiley???? On an audio forum??? I looked twice...did I miss it?
Running the B1K for another hour and playing with the speaker phase I can barely detect a difference between absolute phase and inverted phase, though I do prefer the absolute phase (wires reversed at speaker). My speakers are similar to Pete's Peerless 3-Ways on TechTalk from Parts Express except I have ESS AMT tweeters. The sound is opening up and is perfectly balanced; better than it was last night, perhaps due to the elimination of the hum. However my modded PAS2 still is better in imaging and soundstaging with noticeably better height and image depth. Also as I noted before the PAS2 still has better tangibility too....I thought maybe from its increased H2 but AudioRegenesis tested a mostly stock PAS2/3 and determined its overall harmonic distortion to be at .03%. I seem to be almost the only one who finds his older system to be better 😕😱
Not to say this is by any means bad sounding, it is very clear with excellent channel balance from both the board and the Alps pot. It is musical, and vivid...just not as musical and vivid as what I am used to. Not sure if it could make as much difference as I am hearing but the B1K is using Elna Silmic II's and the PAS2 has cheap film caps from eBay. I am going to try reducing the H2 to see if the sound heads in the direction I am looking for.
There's no Covers Ears smiley???? On an audio forum??? I looked twice...did I miss it?
Running the B1K for another hour and playing with the speaker phase I can barely detect a difference between absolute phase and inverted phase, though I do prefer the absolute phase (wires reversed at speaker). My speakers are similar to Pete's Peerless 3-Ways on TechTalk from Parts Express except I have ESS AMT tweeters. The sound is opening up and is perfectly balanced; better than it was last night, perhaps due to the elimination of the hum. However my modded PAS2 still is better in imaging and soundstaging with noticeably better height and image depth. Also as I noted before the PAS2 still has better tangibility too....I thought maybe from its increased H2 but AudioRegenesis tested a mostly stock PAS2/3 and determined its overall harmonic distortion to be at .03%. I seem to be almost the only one who finds his older system to be better 😕😱
Not to say this is by any means bad sounding, it is very clear with excellent channel balance from both the board and the Alps pot. It is musical, and vivid...just not as musical and vivid as what I am used to. Not sure if it could make as much difference as I am hearing but the B1K is using Elna Silmic II's and the PAS2 has cheap film caps from eBay. I am going to try reducing the H2 to see if the sound heads in the direction I am looking for.
From PassDiy
“Resistors R100, R200, R105, R205 are there to prevent the various potential thumps from switching inputs and turn-on transients.”
Hi Elwood, where did you see this? I just quickly looked at the FW site and the Korg article doesn’t show the revision you’ve mentioned.
Thanks
A limited number (batch 2, 45 units) of the Pioneer's completion kits are now available. The only notable change from batch 1 is the addition of a Euroblock for the potentiometer breakout board. Once these sell out, we'll do a pre-order for a final production batch (during January, for shipping around March). Cheers!
Korg Nutube B1 Full Kit – diyAudio Store
Korg Nutube B1 Full Kit – diyAudio Store
Very interesting wiring there, can you please post a picture from the front panel side as I wanted to see how did you wire the input signal ground wiring coming from the volume/source selector pots.
Thanks