I believe Stephe's original build used different OPTs, then she installed and measured the Thermionic Labs OPTs and low-end frequency/overall response was significantly improved. I would have to go back through the videos to confirm. I am building a pair of these and have the TL OPTs. I just need to get my priorities straightened out and get them done.

Don't underestimate the contribution to good sound that those Thermionic Labs OPTs make.

I believe it's a Sovtek but I can't tell which one.

Nice job! Does it sound as good as it looks?

Measured across the meter (turn power off, unplug, and allow capacitors to dissapate first) you should see the highest resistance (60K, 100K, 300K, etc). Lets assume it is 100K and rotates from 7-5 o'clock. If it is linear, there will be a similar decrease in resistance at each position of the clock. If it is logarithmic, there will not be as much decrease in resistance at 8, 9 and 10 o;clock and usually reads half resistance (50K) at 12 o'clock. The better pot manufacturers publish the taper values and deviation between wafers (Channels) if so equipped. Like Skunkie said, a good quality 100K is typical and other values are chosen for specific purposes. The other question: is the meter and associated circuitry in the right part of the cirsuit? I am a newbie so that is about all I can help with. Good luck.

Could put a meter on it and measure it. You should be able to look at the resistance readings and determine if it's Log or Lin.

Santa arrived a day late. I paid for the Skunkie Spec KT120 OPTs on 07 November via PayPal. They were shipped on 13 December, made it through Customs on 18 December and arrived in Washington State, USA, on 26 Dec. Considering these OPTs had to be built and were shipped during the Holiday rush, I'm very happy. They have that "new transformer smell". They will go on the shelf waiting for me to start building the amps. Meanwhile, I am starting the EAR834 Phono Pre.

Thank you!

Very impressive! A few questions: Are the strongbacks over the caps for containment in case of cap failure? What brand / color is the paint?Does it sound as good as it looks?

You don't see that every day. Nice job!

I got everything off eBay or Amazon except for the source selector knob and volume pot. The selector is a reproduction Zenith "Steering Wheel" and the pot is a Precision Electronics Corp 2RV7, 100k, 2-wafer, MilSpec pot.

Thermionic is in Greece. The shipping cost is likely different than anything shipping from the USA. It is not cheap to get them from Greece to the USA either. Since these OPTs seem to work so well with these amps, I'm going to bite the bullet and saving up.

I used these books to learn electronics in the Navy. It is written for someone who knows nothing about electricity and grogresses as far as you want. This link takes you to a site where you can download PDF of the manuals. "Current" NEETS Modules (USN) in PDF format -Training:COMPATT