Blue Circle TVA Preamplifier - October 2024 Service / Modification

This is a very special one that has come in for repair. The first thing that I do when I receive a component is typically research it, try and find out as much public knowledge as possible before making my own opinions and taking a look myself. Sometimes you find a very interesting story behind the piece or find out about a particular rarity. This is definitely a rarity as it is a one of one custom built component, a preamplifier with an integrated DAC! First video look here at the preamp!

First Lookover - On The Bench  

So after some minor confusion on my part, I finally tracked down the issue in the preamp to the volume attenuator. It had a lot of use over the years and had very little resistance, causing a number of issues throughout the circuit causing this unit to be sent in. Once the new volume was mounted and tested, I went to work adding the two SP jacks to the rear of the unit, one for the analog stage, and one for the digital. Since both stages use the same voltage, I was able to use the SP36 capacitor pack to have some fun switching back and forth adding high capacitance and hearing the affects that it had. 

Unfortunately when wrapping up this service it was a very busy week, and I did not have the time to do the final video showcase that I had planned. It was more important to get this unit home so that I could continue on my backlog of projects. 

Origin of the TVA

After I posted my first look video of the TVA, I had a conversation with Angela-Gilbert about how the TVA came about, as there is essentially no information online at all. This makes sense as evidently this was a one off custom component built by request of a customer to integrate a DAC based off of the BC509 and part of the BC107 preamplifier. The overall tonality of the preamp was much more warm than I had expected for being a completely solid state design, but the quality and connection is still there that is so prevalent in AGY's designs.