Hello, I have been using my 01a for quite a while now, it's based off of Ale's Gen2 Design, and I am still having noise issues despite redoing my grounding, and shielding some of the signal sections. The hum really isn't too bad unless I turn my amplifier up, but the microphonics are a real killer. So much so that if I turn my amplifier up too loud, even with nothing playing, and tap a valve, it will pick up the vibration from the speaker and ring louder and louder. Also, at higher volumes, the tubes will ring on bass notes. I've bought 5 extra 01a's now and these are the least microphonic of the bunch. My chassis is a 12x12 aluminum plate mounted on wood, bottlehead style, connected with umbilicals to my power supply. I know the mounting isn't doing it any favors, but I didn't expect it to be this bad!
My top plates are 4mm thick aluminium, which is probably why I've never had much issue with microphonics. I use plate chokes - don't know if that helps but I don't get noise issues.
It is sometimes worth trying some vibration-isolator interface. Like a 'Rubber Sandwich' at the tube socket's mounting points.
I have not tried these Elesa & Ganter damping-fasteners yet, but they look like the right idea. I plan to buy some when I get a chance; TME in Warszawa has them now:
DVA.2-8-8-M3-6-55 ELESA+GANTER - Vibration damper DVA2-8-8-M3 | TME - Electronic components
I have not tried these Elesa & Ganter damping-fasteners yet, but they look like the right idea. I plan to buy some when I get a chance; TME in Warszawa has them now:
DVA.2-8-8-M3-6-55 ELESA+GANTER - Vibration damper DVA2-8-8-M3 | TME - Electronic components
There's a cheap way of going about this. If the top is aluminum, go look for a 1 - 1.5 mm
galvanize steel plate apply contact cement on both aluminum & galvanize steel plate stick them together when contact cement is dry to touch. Very effective & cheap way to damp resonance.
galvanize steel plate apply contact cement on both aluminum & galvanize steel plate stick them together when contact cement is dry to touch. Very effective & cheap way to damp resonance.
Will the solid core wires to the tubes pins not create a rigid coupling of other vibration to the tube? Should I use different wire? I will post photos tonight.
They might do, depending on the gauge. I like to aim for maximum isolation, above other consideration, & flexible cable is certainly better in that way.
I like the sub-chassis approach too, especially if the floating part is as light in weight as possible.
I use the same solution. Not the specific brand Rod linked, but the same vibration damping bolt/standoff.
Amazon (US) sells them for quadcopters, etc. in m3, which works well for tube sockets, IME.
I get mine from ebay, plus threaded mounting blocks from Burklin. Mounting block | Burklin Elektronik
Similar system to Thomas Mayer.
That is exactly what I did, it's the best way to quiet those tubes.
I had a box of 10 tubes, all very microphonic until I added the volume at output. It works with a resistive volume control as well but the TVC works even better. I went to Dave Slagle for mine
Without low output impedance transformer (for example next stage /SiC/FET source follower, or -at least- CCS/gyrator as active load of tube) it's a bit optimistic advice. :-(
01a has very bad behaviour to such complex load (very high inductance+not so low capacitance) as AVC/TVC. Low output impedance driver helps a lot.
Unfortunate collusion.
I have a dozen of Sylvania 10/10Y tubes. Non of them -very- microphonic in my 10/801 preamp.
I usually use graphite anode 801 tubes, because it's musicality is outstanding.
Using his AVC modules
They work fine driving a 6E5P on my GM70 amps
It also drives my solid state s500 threshold without a problem
No source follower required
The added plus of the autoformer at the output is that your output Z worst case will be the Rp of the tube and will quickly go down as you attenuate. At -12dB you will be around unity gain and have a Z-out of around 600 ohms.
Last edited:
I considered an AVC, but bought a pair of Sowter TVCs already made up into a pre very cheaply. I wondered if the lack of isolation with an AVC might cause any problems, but have no experience of them.
Ale's excellent Gen2 01A design = 18.55dB (or 8.4) gain.
Typical CD Voltage in to the preamp = 2v. That is a pretty high voltage out = 2 * 8.4 = 16.8v .
This is going to swamp the capabilities of most AVCs or TVCs, when they are put on the output of the preamp -- too much voltage in.
Typical CD Voltage in to the preamp = 2v. That is a pretty high voltage out = 2 * 8.4 = 16.8v .
This is going to swamp the capabilities of most AVCs or TVCs, when they are put on the output of the preamp -- too much voltage in.
Last edited: