I have had bad luck connecting static shield to chassis ground in my various builds. Always seems to add hum.
proper way is - mounting one Korg toobsie where it belongs , on pcb , to sing
and second one , just with weemsy heater connected , on front plate , to be seeeeeexy
$50 pilot light
Thanks guys for all the advice insight and suggestions. The hum was indeed caused by my AC line. I bypassed the switch and wired the mains directly to the transformer and got rid of the hum.
But now I have lost the ability to turn on/off the preamp from the front since I cant relocate the power switch. Oh well, that's the price to pay for vanity. ;-)
But now I have lost the ability to turn on/off the preamp from the front since I cant relocate the power switch. Oh well, that's the price to pay for vanity. ;-)
I keep my preamplifiers on all the time, but I always implement an on/switch at the rear (or on that case, on the external power supply unit). I only use that switch when I replace a unit or move around the setup For some reason. It does not use a lot of energy really, and the diyaudio community’s efforts does not add up to a nuclear power plant either. Even including the power amplifiers.
It hasn't changed a ton since the old pictures. I've posted 2 new ones that should showcase changes. There are two grotesque joints; they are functional but cosmetically undesirable, I will fix later.
I should correct my last post. Ringing is still an issue. The tube will go microphonic if I simply blow across it. As I mentioned in a previous post, I wasn't gentle with anything, including the new tube. Maybe I paid a significant price for my stupidity. The cover seemed to stop the ringing one time, but that won't solve problem entirely. I've either got to cover the Nutube itself or replace the Nutube. Desoldering and soldering in a new Nutube is not something that I look forward to.
Attachments
How microphonic was the old tube? How much improvement is the new tube? I'm at a crossroads where I need to either encapsulate my Nutube or outright replace it. Just blowing across the tube triggers it. Once the ringing starts, it seems to stimulate itself and exponentially gets worse.
Get a white pencil eraser and tape it to the top of the NuTube.
https://www.amazon.com/Prismacolor-...JJEHKZ06AP5&psc=1&refRID=KC2VK28WRJJEHKZ06AP5
https://www.amazon.com/Prismacolor-...JJEHKZ06AP5&psc=1&refRID=KC2VK28WRJJEHKZ06AP5
Duct seal might work even better. It stays put and is fully removable with a bit of work.
https://www.homedepot.com/p/Gardner-Bender-1-lb-Plug-Duct-Seal-Compound-DS-110/100212441
https://www.homedepot.com/p/Gardner-Bender-1-lb-Plug-Duct-Seal-Compound-DS-110/100212441
Yes, that is why the kit should include the Korg socket, or that it be sold as an option at the DIY Audio store. Finding it in-stock in the US is near impossible.
place some nice cushion-like block on pcb in place of nutube , say 25-30mm thick
glue lightly nutube to cushion
use thin wires for connection between pcb and nutube
that's probably all you'll need of cushioning with decent nutube specimen
if you need more , even pouring concrete in da box wouldn't help much
glue lightly nutube to cushion
use thin wires for connection between pcb and nutube
that's probably all you'll need of cushioning with decent nutube specimen
if you need more , even pouring concrete in da box wouldn't help much
This is typically the filament ringing at 5 - 6 KHz. Of the 6 tubes I've used in various circuit builds, I've only had one that rang when tapping lightly on the glass and the ringing would die out quickly. I used this to dampen it (sticks really well):
https://www.amazon.com/Duck-Reusable-Removable-Mounting-1436912/dp/B000BQMFEC
It seems if ringing is so bad it is self sustaining, it would be best to replace the tube.
I have the F6 and went from passive attenuator to B1 (buffer only) to B1 Korg. Attenuator to B1 was very subtle improvement. B1 to B1K was a much greater change. Music became more exciting and involving but not in a false or fake effect kind of way. I highly recommend the B1K with the Pass amplifiers.
Every friends at music session with B1Korg preamplifier liked a lot.
Sometimes without knowing what was new
Occasionally it will starting ringing and just continues to get louder and louder; putting the lid on solved it one time. Unfortunately, my design is hybrid power amplifier. So I have no volume pot, meaning the ringing is at full amplification no matter what my source is set at.
Like I said, I wasn't gentle with the Nutube. If I am desoldering and re-installing, I will opt for the socket this time around.
Same experience here, with the same Schiit (pun intended), B1 and B1Korg with F5. It is worth it.
