Hello all. Received my Nutube from the diyaudio store and the “metalwork” around the triode on one channel is a bit crooked. I haven’t put anything together yet so don’t know if is an issue... Does anyone else have one that looks like this on the inside?
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Those look like the grids. Don't know if slight asymmetry would effect performance one way or another but I would suspect not. Regular vacuum tubes have lots of small irregularities even in matched tubes.
Mine is ever so slightly crooked on one side. Manufacturing variation I guess, hopefully it won't affect performance.
Does yours have the circle thing on the back like mine?
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Pass DIY Addict
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Yes, I got my from a Danish "car parts chain shop" where you can buy online:
Resonansplader 4 mm, 50x50 cm, 4 stk. - Lyddaempning - thansen.dk
4mm and with adhesive. Guess same kind of stuff exists in US.
Resonansplader 4 mm, 50x50 cm, 4 stk. - Lyddaempning - thansen.dk
4mm and with adhesive. Guess same kind of stuff exists in US.
Mounting the Nutube on the front panel is certainly something to consider.
It is currently damped underneath by a strip of Focalpod lossy rubber and seems reasonably well cushioned. I remembered that I had an LDR attenuator (from a group buy a few years ago by dvb projekt) in a box so I'm going to use that. Just playing
It is currently damped underneath by a strip of Focalpod lossy rubber and seems reasonably well cushioned. I remembered that I had an LDR attenuator (from a group buy a few years ago by dvb projekt) in a box so I'm going to use that. Just playing
to MARRA
I mounted my NUTUBE with rubber grommets around the screws to the
frontpanel (which is 10mm thick and heavy).
No microphonic problems. You have to shake the case or knock with the knuckles on it to hear something.
My NUTUBE has also that round plate on the backside - don't ask me for what
reason or what the function is?
Greets
Dirk
I mounted my NUTUBE with rubber grommets around the screws to the
frontpanel (which is 10mm thick and heavy).
No microphonic problems. You have to shake the case or knock with the knuckles on it to hear something.
My NUTUBE has also that round plate on the backside - don't ask me for what
reason or what the function is?
Greets
Dirk
Mine is soldered to the PCB and has 3m adhesive backed foam underneath. The PCB is mounted in the slots on the side of the case so no further damping is really possible there. The case has rubber dome feet which isolates the case from the surface a bit.
I get microphonics if I tap the case or jolt it, which is fine as it won't generally experience those vibrations in use.
But.. I get a wicked ringing when I click the input switch over from one channel to another. It lasts for 20-30s or sometimes much longer and is a mid-high frequency ringing. I'm trying to figure out how to tame it without replacing the switch.
I get microphonics if I tap the case or jolt it, which is fine as it won't generally experience those vibrations in use.
But.. I get a wicked ringing when I click the input switch over from one channel to another. It lasts for 20-30s or sometimes much longer and is a mid-high frequency ringing. I'm trying to figure out how to tame it without replacing the switch.
That could well be it. I didn't really pay too much attention to the circle when I got it (too many shiny things to distract me) but when I looked through my photos I remembered seeing it and wondering.
Eric, Parts Express may still have it. Crutchfield or any decent-sized car audio shop that's nearby should have them as well.
FWIW,
When damping sheets first showed up in car audio, I remember reading somewhere that VOC off-gassing from bitumen (asphalt) sheet could potentially cause trouble with speaker adhesives or butyl rubber surrounds, or both.
Obviously, I'm no expert. I don't remember much other than it may not be a good idea to close them up inside a speaker box or near a speaker on a door skin where it can get very hot.
It may have been a marketing ploy by the major player, Dynamat, to keep us from looking for cheaper alternatives to their product.
I'm considering other mounting/damping alternatives, but not for fear of VOC's
To really get rid of the specific frequency that starts the ringing you would have to isolate the solder connections that make it rigid.
Either the whole board isolated ( difficult ) or korg triode panel mounted with flexible wiring
And foam captured body surrounding the piece.
Regards
David
Either the whole board isolated ( difficult ) or korg triode panel mounted with flexible wiring
And foam captured body surrounding the piece.
Regards
David
You can use any of those values. The 10 and 20K are a bit low for some
people, but no problem for the preamp. At 100K you do see a small loss
of extreme top, but this is not a big deal - there is greater loss at the
Nutube output impedance.
I was not sure where to post this question, but I have a Millet NuTube buffer board and when completed and hooked up to a 12v 5ah battery I get a loud buzzing sound. Could this be a ground issue? It is very loud and has to be shut off immediately. Does there need to be a chassis ground? Sorry for the basic question this is my first project. Here are some photos of the board, power supply, and volume pot:
I did have trouble soldering the board, in that I put some of the caps the wrong way and had to redo them, so some of the solder joints might not be great.
Any help appreciated. Thanks!
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I did have trouble soldering the board, in that I put some of the caps the wrong way and had to redo them, so some of the solder joints might not be great.
Any help appreciated. Thanks!
Pass DIY Addict
Joined 2000
Paid Member
Thanks for recommendation, Tim - I wasn't thinking of these sources.
I finally put my bare boards into a chassis. The chassis came with a nice 10mm front panel that was too think to allow me to mount the controls and switches, so I replaced it with chunk of cedar left over from a closet project. I still need to replace the silver screws on the front panel with black ones and add a knob to the volume pot. The combination of the stepped attenuator and aluminum chassis makes things resonate a bit, so I need to add some damping to the chassis and add some rubber grommets to the PCB mounts.
I LOVE the sound when combined with my MoFo amp! I'm likely to complete my VFet2 amp next, so I'm looking forward to that combination, too!
I finally put my bare boards into a chassis. The chassis came with a nice 10mm front panel that was too think to allow me to mount the controls and switches, so I replaced it with chunk of cedar left over from a closet project. I still need to replace the silver screws on the front panel with black ones and add a knob to the volume pot. The combination of the stepped attenuator and aluminum chassis makes things resonate a bit, so I need to add some damping to the chassis and add some rubber grommets to the PCB mounts.
I LOVE the sound when combined with my MoFo amp! I'm likely to complete my VFet2 amp next, so I'm looking forward to that combination, too!
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Did you power the board up with the capacitors the wrong way round? If so they may need to be replaced.
You definitely need to go over your soldering. The solder should ideally flow from the bottom surface to the top - for example the diode D1 has big air gaps.
Do you have any pics of the bottom side?
Do you have a multimeter?