Update: I wasn't able to get rid of the extreme microphonics. I tried using vibrapods under the preamp and under the board. I tried unscrewing the board from the standoffs. I tried suspending the board from wires inside the chassis. I'm going to order some sorbothane washers, feet and a pad for under the NuTube. Until then...
Also, anyone seen this:
Guide | Nutube – English
Korg mentions a case that is supposed to reduce microphonics. Anyone try this or know where to obtain one?
/d
Guide | Nutube – English
Korg mentions a case that is supposed to reduce microphonics. Anyone try this or know where to obtain one?
/d
Has the pre-order started yet? I received the pioneer batch email, but curious if i missed the main preorder. I too would like the option in silver for the preorder.
Thanks
Jim
Needs a standalone PCB with some slots in it to take a 3D printed cover. A couple of skited tabs would do it. The article also suggests using a lead shield! You could cast one of those.
...4) I have some Vibrapod feet in a box I will try. After that I'm not sure. The ringing is WAY TOO MUCHat this point to actually use the preamp - turning up the volume is all but impossible - so I'll need to come up with something.
More soon.
Back when the Nutube first came out I built both Pete Millett's Nutube buffer and his headphone amp/preamp.
I was never sure if it was only the difference between the two Nutubes that caused it but on the buffer I got very minimal ringing and yet on the headphone amp it was really bad. Even just brushing against the headphone cable with no music playing generated a faint distant ringing sound.
https://www.diyaudio.com/forums/pass-labs/313612-b1-korg-triode-3.html#post5216410
I eventually parked it and moved on as the responses at that point were pretty much all certain that the Nutube couldn't possibly be that microphonic...
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I have this:
DIY Audio Projects - Hi-Fi Blog for DIY Audiophiles: Oatley K272A Head Amp audioXpress Review
The two tubes in the kit came with rubber rings similar to those used on full size tubes. Maybe a couple of elastic bands is what’s required. My head phone amp still rings but only if you knock it. I used a neutrik jack socket mounted on pesrspex lid so no mechanical connection to the board other than the wires.
DIY Audio Projects - Hi-Fi Blog for DIY Audiophiles: Oatley K272A Head Amp audioXpress Review
The two tubes in the kit came with rubber rings similar to those used on full size tubes. Maybe a couple of elastic bands is what’s required. My head phone amp still rings but only if you knock it. I used a neutrik jack socket mounted on pesrspex lid so no mechanical connection to the board other than the wires.
It has not started yet, and it looks like we'll be doing another batch of 45 very shortly to clear out current parts stock then doing a pre-order for a fresh buy of new parts after that. Nothing is confirmed at this stage and things happen when they happen on this one, but I've heard that next batch of 45 is very close. Jim's very busy at the moment.
Work is nuts, Burning Amp is this weekend, I'm waiting for knobs to arrive from the other side of the world, and something else that escapes me at this moment...
But I will tell you that all the other parts are currently bagged up in their little sub-packages awaiting the rest of the bits to arrive.
It won't be long.
But I will tell you that all the other parts are currently bagged up in their little sub-packages awaiting the rest of the bits to arrive.
It won't be long.
BAF 2019 was a great time. Had an opportunity to attend the test and measurement workshop, listen to some great talks and listen to many outstanding projects. I have attended many BAF’s and this one was one of the best I’ve been too. It was quite a global crowd and there were plenty of speakers to pair with amps.
For the B1 with Korg NuTube chassis, I would recommend a chassis with no ventilation slots to seal up the chassis. When I cover the slots on the chassis, I have no problems with microphony. Additionally, I used the vibration-damping standoffs used by drone builders. Both of these measures completely cured the microphony issues and preamp sounds awesome and looks great.
For the B1 with Korg NuTube chassis, I would recommend a chassis with no ventilation slots to seal up the chassis. When I cover the slots on the chassis, I have no problems with microphony. Additionally, I used the vibration-damping standoffs used by drone builders. Both of these measures completely cured the microphony issues and preamp sounds awesome and looks great.
My microphony is not too bad, but I'd like to see what can be done to reduce it. Where can I get those standoffs? Could you please post a source of what you used? Something like this? Spektrum Nylon Standoffs/Hdwe Set for Drone Racing | TowerHobbies.com
Thanks in advance.
I’m experimenting with microphony reduction, I have one that’s pretty bad. I’m going try soft mounts, softer mounts, silicone washers, sorbathane, and other things.
Resting the chassis on Vibrapods or similar very compliant feet is quite helpful.
Will report on my findings when I get them.
in the meantime, please post to the thread with your solutions!! The NuTubes themselves seem to be pretty variable in microphony, some people have issues, some dont, so I think it’s going to be an ongoing thing to find what works. The circuit is absolutely wonderfully sounding so it’s worth the effort.
Resting the chassis on Vibrapods or similar very compliant feet is quite helpful.
Will report on my findings when I get them.
in the meantime, please post to the thread with your solutions!! The NuTubes themselves seem to be pretty variable in microphony, some people have issues, some dont, so I think it’s going to be an ongoing thing to find what works. The circuit is absolutely wonderfully sounding so it’s worth the effort.
Here’s a link to the iFlight vibration damping standoffs and Nylon nuts:
https://www.amazon.com/dp/B073NYV6RH?ref=ppx_pop_mob_ap_share
https://www.amazon.com/dp/B073NYV6RH?ref=ppx_pop_mob_ap_share
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Never one to leave well enough alone, Having mitigated the microphonics with the sorbothane washers, I thought I would risk everything and try a film coupling cap upgrade.
I did like the sound with the Nichicon Gold caps. It was fast and detailed, if a little dark and unrefined.
I had trouble finding good polypropylene caps that would fit. I had seen an old post where the builder had used a 0.22uF cap on the input buffer, 1uF on the tube, and 4.7uF on the output. I used that as a guide. I managed to squeeze in 0.47uF Dayton film and foil on the input, 1uF Solen in the middle and 10uf Solens on the output. The sound is much smoother and creamier but I think I lost a bit of the punch and liveliness of the Nichicons. It sounds more like my “big” tube Preamp but darker and recessed. The sheer amount of distortion started bugging me after a while, 2nd harmonic or not. I tried raising the B+ up to 12V to hear the Preamp at its minimum distortion (0.3% according to Papa). The B1 was much cleaner then, but it had lost much of its tube character. As a compromise, I tried dropping the B+ to 11.5V which has given me a bit more of the tube sound back. I’m guesstimating that I’m at about 0.8% THD now. I like the sound at this point which sounds clean but still has a hint of tube character. The big mu-follower Preamp still beats it but the humble B1 comes close.
Surprisingly, the microphonics problem did not worsen with the big caps hanging off the board. The big 10 mike Solens barely fit between with PCB and the input jacks.
BTW, I sealed the vent holes in the top and bottom plates of the case with several layers of duct tape to inhibit external sound intrusion. I have recommended to the folks at the DIY store that they lose the vent holes in the next generation of kits. I’d like to see a retrofit kit with plain top and bottom plates for us prelim kit guys.
Eventually I may try another NuTube just to see if I can get one with better channel matching, of course less microphonics would be nice too.
Do my experiences match yours? Thanks for all the good advice.
This is an amazing little Preamp managing both soul and punch for a reasonable price. Papa Pass has created another exciting design. The ability to dial in just the right amount of warm tubey goodness makes it acceptable to a wide range of audiophiles. I’d love to slip a non microphonic Korg B1 set to minimum distortion into the system of a diehard solid state guy and see how long before they are beguiled by it.
I did like the sound with the Nichicon Gold caps. It was fast and detailed, if a little dark and unrefined.
I had trouble finding good polypropylene caps that would fit. I had seen an old post where the builder had used a 0.22uF cap on the input buffer, 1uF on the tube, and 4.7uF on the output. I used that as a guide. I managed to squeeze in 0.47uF Dayton film and foil on the input, 1uF Solen in the middle and 10uf Solens on the output. The sound is much smoother and creamier but I think I lost a bit of the punch and liveliness of the Nichicons. It sounds more like my “big” tube Preamp but darker and recessed. The sheer amount of distortion started bugging me after a while, 2nd harmonic or not. I tried raising the B+ up to 12V to hear the Preamp at its minimum distortion (0.3% according to Papa). The B1 was much cleaner then, but it had lost much of its tube character. As a compromise, I tried dropping the B+ to 11.5V which has given me a bit more of the tube sound back. I’m guesstimating that I’m at about 0.8% THD now. I like the sound at this point which sounds clean but still has a hint of tube character. The big mu-follower Preamp still beats it but the humble B1 comes close.
Surprisingly, the microphonics problem did not worsen with the big caps hanging off the board. The big 10 mike Solens barely fit between with PCB and the input jacks.
BTW, I sealed the vent holes in the top and bottom plates of the case with several layers of duct tape to inhibit external sound intrusion. I have recommended to the folks at the DIY store that they lose the vent holes in the next generation of kits. I’d like to see a retrofit kit with plain top and bottom plates for us prelim kit guys.
Eventually I may try another NuTube just to see if I can get one with better channel matching, of course less microphonics would be nice too.
Do my experiences match yours? Thanks for all the good advice.
This is an amazing little Preamp managing both soul and punch for a reasonable price. Papa Pass has created another exciting design. The ability to dial in just the right amount of warm tubey goodness makes it acceptable to a wide range of audiophiles. I’d love to slip a non microphonic Korg B1 set to minimum distortion into the system of a diehard solid state guy and see how long before they are beguiled by it.
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