June 29, 2026
#545
Gentle reader,
I have two readers whom I have become friends with AND met. One, Bob B. lives in the West ("The Far West").* The other, Bruce W. lives north of where we do. Both have become dear friends whom I truly love as brothers. *A line from the epic film, RANGO starring Johnny Depp as the title character, below on the left.
Longtime readers of this blog may remember articles in which I mention one or the other of my blog friends. For instance, Bob owns and runs the Dynaco Museum. Plus, he lives in the same town my Aunt Beverly does. Bruce and I might have crossed paths in 2002 when I attended the Inaugural Cadillac Grand Prix of Washington D.C.
A week long racing event put on by the American Le Mans Series. I attended the races and Bruce was working as a corner marshal. It was being relatively local which brought Bruce and us together twenty years later.Anyway, Bob thought it was a good idea that all three of us build Tube Buffers from kits. He outfitted all of us with everything we needed. I wrote about it here: The Robb Collections: UPDATE Inexpensive Chinese-Made TUBE BUFFER amplifiers. A Review of One using 6J1 Tubes Upgraded to GE JAN 5654W Tubes
This image is from one of the eBay sellers of these kit and prebuilt tube preamplifiers.
Well, Bruce and I got together earlier this month at a car show in which I was one of the judges. 122 cars showed up, including Bruce's brand new Porsche 911 GTS. Wow, what a car! Anyway, it was "old home week" for Bruce, Nancy and I.
Bruce brought me the 6J1 kit Bob sent him and other things since he was never going to do anything with them and gave everything to me. I decided to do a comparison of the two of them by seeing if they could drive headphones and whether I could hear any improvements in the sound of the music as a result of it passing through tubes.Headphones are small speakers, sometimes incredibly small drivers in the case of ear buds. I have owned many since the 1970's. I have Audio-Technica AIR ATH-AD700X, an improvement over the ones I first tried years ago which are pictured below.Image courtesy of i.ratings.com
I had an earlier iteration which were designed to rest ON your head rather then clamp onto your head, shown below:
Much more colorful too.
The present ones I only bought when one channel stopped working in the old ones after many years. Their plug appeared to be solid machined brass and 1/4" only. But, Audio-Technica were clever in machining it to seem that way. The 1/8" plug was inside, but one unscrewed the bigger plug to get to it. The new one's plug is not as fancy, nor are the headphones, visibly, by comparison. They do clamp a little bit, but not excessively. And they sound fantastic!
In order to use each of the tube preamplifiers with headphones, I had to find well made cables. I looked on eBay, but was not finding what I needed. I always sigh when I have to turn to "The Jungle Site" to buy things. They LOVE Nancy and she loves them! Anyway, these are from different companies in China and are both well made. The OCD in my brain is trying to make the fact that the left cable on the female unit on the left is a shade too long is a problem. It should not have left the factory like that! Do they not have Quality Control people??? Okay, I feel better now.
What's inside the box holding the AIYIMA T2 6K4 Tube Preamplifier.
The front panel, nicely laid out and neat.
The rear terminals. Red rubber cap is over the Bluetooth antenna terminal.
I was surprised to see an assembled 6J1 Tube buffer board in the box with the unassembled one and all of it's parts. That is what gave me the idea to try this experiment. Note the transformer I found to make it work. These preamps require 12 volts AC to work. DC will fry them. Note the beefy but compact transformer above.
Years ago, in order to get them to work, I found three of these landline Telephone transformers. There seemed to be ONLY three of these on the entire Internet, back then.There was exactly ONE 12 VAC transformer on eBay this time. It cost me almost forty bucks. It puts out 40 amps(!) with a choice of 12 VAC or 24 VAC depending upon the output terminals used. Input wires are two black and one green. I had a short piece of grounded heavy duty 120VAC 16 gauge wiring cable with one green, one white and one black. Since it's AC, it did not matter choosing black or white in this case.
Fortunately, I saved the images which include the schematic of the board. The RCA terminals are not marked for input or output. They are now.I tried the 6J1 preamplifier first. There was definite distortion if the volume was too high during crescendos. So, this little tube preamp is not improving the sound.Next up was the AIYIMA T2 preamplifier.
The difference was startling in just how much better the AIYIMA T2 preamplifier sounded! No distortion unless overdriving it by too much input volume.On the converse, once I removed the AIYIMA T2 preamplifier and associated cabling, and listened to the same music via the B&K Components Sonata PRO10 preamplifier's built-in headphone circuit, I realized that adding anything between it and a pair of headphones was NOT going to be an improvement. Still, despite the work and cost to put it all to a test, I did enjoy doing so.
Thank you SO much for taking the time to read this article. When I first began blogging way back in 2008, I had no idea if anyone was going to read it. It was just something different to do. Well, it took a while, but the word spread and as of this writing, there are 783901 of you out there reading it! I am truly humbled.
Scott Robb June 29, 2026
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