What makes a valve fail in your amp Let’s have a light look at valves. Ever wondered why if you buy a nice new valve ( tube) amp that the amp has 2 years warranty and if you check the small print on the warranty carefully, you will see the valve warranty is a lot shorter – perhaps only 90 days! Valves are very old electronics technology. They were invented in 1910 and have been […]
Vox Amp Schematics Valve and Solid State -Updated 13th Nov 2023 This post used to link to Korg who had kindly gathered together the schmatics of a whole pile of Vox Amp schematics from about 1960 onwards. I posted this in 2019. Korg has now removed this page from their site. A good alternative reference is on the Vox Showrrom page Click here for the link Moat of the Vox AC XX models are there
Fender Amp Serial Numbers There used to be a link on the Fender website for amp dating from the serial numbers. However Superior Music has done a really good summary and here is a link to their website. This will enable you to figure out the year your amp was made.Link ==> Superior Music – Fender Amp, Amplifier Serial Numbers. It is also worth looking up on the Fender website too. I only found this
Here is a good video on Youtube on how to bias a valve /Tube amp. It is a good introduction on what is involved for those with basic electric skills. How to Bias a Tube Amp Part 1 – YouTube.
This weekend, I worked on a lovely 6 year old, Marshall DSL50 amp head. This was the unit I mentioned in a previous post that was awaiting my attention. It was working however the output valves were mighty hot. I checked the bias on those two beautiful EL34’s and found I could not adjust the bias below 68mA. They were running at 90mA when I first tested the amp. (Update Feb 2018 : we now
Belcat 20R Service I had a Belcat Tube amp in my workshop. this was distorting but not in a nice way. It really made your ears hurt! This is a Fender Blues junior copy. The rectifier is solid state and there are three ECC83’s and the output is two EL84’s. I tested the valves on my tester just to make sure they were OK and they were perfect. I again replaced the output protection diodes
Restoring Fender Deluxe Reverb Silverface or Blackface amp part 3 – resistors In common with all Fender amps they are mounted in the case “upside down” the valves hang at the bottom for east access. The trade off with this design is that heat rises so all the heat from the tubes/valves rises and it cooks all the components over time. A silver face amp is a minimum of 35 years old and so the
Restoring Fender Deluxe Reverb Silverface or Blackface amp part 3 – resistors Read More »
