Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Koyaanisqatsi on November 24, 2025, 07:30:30 pm
-
Hello everyone! I’m new here and looking for some help. I recently built my first tube amp from a KLD kit, but after checking and rechecking my work several times and contacting KLD, I can’t figure out what the hell is wrong with my amp. It’s got a really nasty buzzy and deep fried tone (listen here https://drive.google.com/file/d/1BrCUbxQeW_a1qiNMxya6ecsnRg17UHjt/view?usp=drivesdk (https://drive.google.com/file/d/1BrCUbxQeW_a1qiNMxya6ecsnRg17UHjt/view?usp=drivesdk)). I’ve tried measuring the test points but to be totally honest, I cannot for the life of me figure out how to set the bias to -30V as recommended by the test sheet. I’m not a total amateur when it comes to electronic work but I’m by no means a pro, just a hobbyist looking to save a bit of money by doing things myself instead of shelling out hundreds on a new or vintage amplifier. Someone help me! I attached some photos of my work as well as the KLD layout/schematic provided with the kit here: https://drive.google.com/drive/folders/1E9y3zvgA94OZ85eEbGHvKS6u_U1v7qUH (https://drive.google.com/drive/folders/1E9y3zvgA94OZ85eEbGHvKS6u_U1v7qUH)
-
Not a very simple amp for a beginner. There is one voltage chart you could use to compare under load, but before I did that, I would pull all the tubes and check bias voltage and adjustment, as well as all the voltages at each node. These are normally things to do before installing tubes, and with a light bulb limiter to protect against shorts.
There's also a link somewhere in this site as a general start up procedure as you build, but I can't find it at the moment.
-
Not a very simple amp for a beginner. There is one voltage chart you could use to compare under load, but before I did that, I would pull all the tubes and check bias voltage and adjustment, as well as all the voltages at each node. These are normally things to do before installing tubes, and with a light bulb limiter to protect against shorts.
There's also a link somewhere in this site as a general start up procedure as you build, but I can't find it at the moment.
I did lose my head a little jumping into a build like this one (I probably should’ve gone for a 5e3 haha) but what can I say, I like a challenge. Surprisingly, when I turned on the amp to run some tests just now I noticed that after spinning the bias pot a few times I was able to get a crystal clear signal. I think I’m gonna try replacing that tomorrow, and cleaning up any solder joints in that area. Fingers crossed!!
-
https://el34world.com/Forum/index.php?topic=2376.0
This thread might help. It's got a sticky, so must be good.