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In the Forum: Audio Discussions
In the Thread: It’s mad, mad, mad... electricity.

Post Subject: Converters within amps etcPosted by JOHNR on: 10/16/2015

To answer the question WRT reliability.
I have built wholly switched mode amps with 2A3, 300B and now a 45.

I also have a DAC 44 K only, no over sampling, no attenuation and 1 clock cycle switching into 1704 chips. The design focus on the DAC has been the absolute removal of all high frequency noise thus, it is quiet!! It removes the low level shadowy noise that lays behind all signal processing and the DCS owner spotted that immediately. It was A-Bd with a DCS system using their master-clock and it came out quieter.

Reliability - one system using the DAC, an associated Line Amplifier driving a pair of 2A3 amps working into a small horn system has been running for 6 years and to be noted, it has only been powered down once by the owner for a house move. The EML power tubes have now run for more than 20,000 hours.

With regard to the DAC power, I use a series/shunt supply that I use for all tubes. It is small, 4 by 2 inch and I fitted a trim-pot to make it universal. Otherwise, a fixed resistor is used for reduced drift and improved reliability.
This package is aimed at the DIY guy who can experiment with different tubes. It has seen service on 10Y, 801, 6C45, 45, 6N1 and a number of DACs.

I am not a manufacturer however, I would like to see this particular unit in wider use because it really does make a difference to even the humblest tube, DHT and IDHT.. It is NOT cheap even when you build it yourself

In relation to phono stages, I have not built one. I should point out that the shunt section of the circuit is limited to 6.5 volts and 3 amps as it is a commercial product.

Hope this helps.
John

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