Douk AudioNobsound Vacuum Tube Amp Amplifier Plate Bias Current Probe Tester 8 Pin Socket for EL34, KT88, 6L6, 6V6, 5881, 6550, KT66, KT100, KT120, 7027 (CT1-P, Plate Current)

These are nicely made, quality bias probes. I saw some reviews complaining about the length of the wires but I think they have extended them because the wires on mine came about twice as long as pictured or the measurment listed. In any case they are plenty long enough to get the job done now. Get one for each of your power tubes, two power tubes, get two, four, get four. You don't want to bother with having to switch the probe back and forth and waiting for the tubes to cool and warm up. Get one for each tube and even better get a meter for each probe. There are plenty of $10-20 digital multimeters that will work perfectly. for this. Most imnportantly be safe. You should not be connecting or disconneting anything without the amp off, unplugged, and the capacitors drained.

For the price I was not expecting much but this is actually a great little device and is not as expensive as other bigger names. I used it to bias a Deluxe Reverb Reissue, 6V6 and worked great! So much easier and safer than probing tube sockets in the chassis.The leads are not very long though, so keep that in mind. Plus, if you’ve not done this before, the leads are dangerous if in the tube socket with the amp on and out of standby. Make sure those leads are inserted in the multimeter prior to energizing the amp.Also make sure to let the tubes get good and hot, settled in before final bias. I actually like to get new tubes that have had a 24 hour burn in time to help.

Works good

I've just gotten started building and designing hifi/guitar tube amps. The tube adapters greatly simplify taking measurements. My only negative is that longer leads would be easier to work with, otherwise, great time saver. Also, while I like monitoring with analog metering, I ended up buying a pair of inexpensive AstroAI non-autoranging DMM's for under $12 each instead of the dual meter unit that is often sold with these.

These are better quality than I expected. I tried them out with my tube tester and they worked great. Just wish the leads were a bit longer and could reach either the floor or top of an amp when in use. Being able to put the meter down while adjusting bias would be helpful.

They literally had one thing to get right... and they f-ed it up. Plug it into your multimeter reversed (red to black; black to red) and it's fine. The wire is short, the gauge is thin. The plugs are low quality. Just a really bad purchase.

Worked

This is the second one of these that I purchased from the same seller. The first one did not work correctly it was intermittent and the polarity of the wires is reversed.Same goes for this one. Knowing that you're reading a negative voltage why don't they have the polarity of the leads correct?This only applies if you are using an analog meter.... If using a digital meter it will show a negative voltage as it should. Just a heads up.The socket portion seems to be well made however the thin leads are stiff and really need to be longer in my opinion. At some point I'm going to modify mine with longer leads so I can set the meter atop The amplifier that I'm testing the tubes on.

Worked very well, easy to use. Decent quality.

No funciona, pone en corto los amplificadores, no lo usen !!

To be honest, I haven't used it yet but it looks to be of good quality. Wires could be a bit longer to make it more convenient

Fast delivery. I haven't used it yet but it looks like a good ceramic base. The leads look very low-grade thin, maybe 24-26 awg so I hope they are ok.

Worked as described. Was able to read my plate current easily on my tube amp. Great tool for checking the bias of your tube amp. The leads could be slightly longer but, still a good product.