Goodbye 814SE Amp, it’s been a fantastic journey

After 2 years of listening pleasure, it’s time to retire the 814SE monster amp. With its breadboard nature and high voltages around, this is not safe to have around with my daughter now being 8 months old. Sad to see this amp go and I hope to listen to it some time in the future.

What is was really painful for my back was to lift this ton of iron up to the attic. It’s so heavy and not keen to move it for some time. This amp has been a fantastic learning experience for me, as well as a huge challenge. High voltages, A2 operation, DC-coupling and the mix of sand with plenty of iron here in a 100% DHT amp was the right mix to give me several headaches along the build and testing stages. However, it’s a beauty to listen to, in particular thanks to the 46 and 814 valves which are unique in my view for this circuit and also the optimal tuning of the operating points and the iron used.

Enough for now, however I’m still working on my safer 4P1L PSE amp, so watch this space 🙂

814 SE Amplifier: measurements

It was time to take the 814 SE Class A2 amplifier measurements. The challenge though, is that the amp is so heavy that I will never take it up to the workshop. Therefore, I decided to take my workshop PC down from the loft this time to see how the 814 really responded.

First test was to do a THD analysis as a function of the total output power. As you don’t want to do this with your speakers, and also the classic wire wound resistors (Alu-clad) are inductive, you want to use non-inductive resistors like this test jig:

20140422-125905.jpg I bolted on to a large heat-sink an array of resistors to form 8Ω in value by using a pair of 10Ω in parallel and three 1Ω in series.  I added a set of binding posts and connectors for the speaker cables. this way you can easily wire your speakers and connect your audio test set to take the measurements.

 

 

 

 

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