Bias Probe for Octal Base Power Tubes.

An excellent tool, offers a lot more piece of mind and ease to bias my amp.

And top quality parts and tools.Eddie has been helping me suss out some issues that I am sure are pedestrian to someone of his vast knowledge and experience in all this, but he's been super cool and patient. In the end, although I have purchased tubes and parts from several outfits over the years, Eurotubes get all my business from now on. I would highly suggest you do the same.A bit of a story here. I have a good friend who for many years custom built some of the best tube amps in the US. He retired from it some yrs back and we lost touch. While attempting to reconnect with him since my amp appeared to be having some minor issues I purchased this Bias Probe from ET to begin testing things myself. Part of my issue was that some of my tubes were new/old stock when the amp was built some 12 yrs ago and some were now unmarked. Long story, short, I lined out the amps "sound" issues with Eddie at Eurotubes and sent him pics of the inside of the amp.While he was researching the issues and considering which tubes I should change to, to achieve more clean headroom, I finally heard back from my old friend Dr. J. Did I mention he worked as an electrical engineer dept head at Los Alamos lab? Yeah, this guy knows more about high-end electronics than most people alive which is why his amps rocked. Additionally, since he had special parts access all those yrs, his amps were built with all Mil-Spec parts which are far superior to anything commercially available in any era. Dr. J lined out a new set of tube types that would get me where I wanted to be, most of the tubes were not exactly what I would have expected. And they were NOT the tube sets that other tube company's advised me to get. My point? When Eddie of Eurotubes got back to me a day or so after that, he advised me to try using the IDENTICAL set of tubes and in the EXACT same locations as my friend Dr. J advised. Now, what does that tell you about Eddie and Eurotubes? It is not often we find "experts" in any field who are actually "experts" outside of their own imaginations. Eddie is one such person and Eurotubes is obviously that as well.

To start, I had an issue unbeknownst to me with my meter. A Klein mm300 which is a fine meter for the price but, has a lower amperage ceramic fuse on the low current side which was faulty in my case. I emailed Eurotubes through the Amazon support and directly through their website. Less than 30 minutes I received a call from Eddie. (Supurb customer service) He looked up my meter (actually the three of them I had before me) and walked me through troubleshooting the probe itself, which tested just fine. Stayed on the phone with me until I verified my Kleins faulty fuse.Fuse replaced and all is right. Eddie took the time and explained exactly how this probe works, and it's genius is in its simplicity. High quality components and so easy to use. I wouldn't hesitate to use this, ever.Eddie, if you read these Amazon reviews thanks man. I really appreciate you going through it with me. You've got a new customer.

I used cathode biased amps for a long time and never had to worry much about biasing but after recently purchasing a '68 Custom DR I found myself back in the adjustable fixed bias world. A couple of these made the task of biasing that amp quick, easy, and safe. You could probably get by with just one but having two makes switching between tubes quicker. Of course, getting a bias meter that accommodates two or four probes would be the ultimate in convenience but I'm not an amp tech biasing amps every day so for me it's not worth the extra scratch. These work fine for my needs. Just be sure to read the instructions about how to safely use them with your multi-meter.

The bias tool works flawlessly and Eurotubes has been my preferred place to buy more than just probes and they have the best customer support. I had a gt bias probe and it did not compare to the Eurotubes probe.

Measures current draw of power tubes. Make sure you don't use on "DC volts" like many bias probes, this one you set your meter to DC amps, it does not use the 1 ohm resistor method.

At least one. Makes checking tube bias against faulty tube amp meters easy, and necessary given that some of the meters aren’t THAT close to ideal biasing.I have two DMM that read in mA so with one in either channel, I can bias first one channel’s tubes, then go to the other side, EZPZ and now I know where the needle SHOULD read for 70%.ONLY complaint is, these hold the tube pins SO tightly, compared to the stock sockets, it’s a little hard to pull the tube out of the adapter. But that’s actually a good thing. Tells me there’s one more thing in my amps I can look forward to changing in future.

Received these across country in just couple of days. High quality product.