ARTA Measurement interface part 1

ESI Juli@ Breakout Cables

DT667 created "breakout cables" for ESI Juli@ 192KHz/24 bit soundcard.

The soundcard has an option of using either : a) balanced TRS 1/4" male cables or b) single ended male RCA cables . The idea here is to create a "soundcard socket saver" so the soundcard connections will not be damaged by repeated insertions and removal of cables.

Single ended RCA cables were created using MOGAMI 2330 Low Noise Wire and high quality male RCA connectors. The male RCA connector were soldered to one side of the wire, the other side was left stripped.

Insulated female RCA jacks were installed into the side cover of DT667's uATX form factor PC case and the stripped ends of the MOGAMI wire was soldered to them.

Note : DT667 splices the center connector and shield of the MOGAMI wire together for extra strength. The center connector is very thin gauge wire that can break easily if not given proper strain relief. So you will have one jacketed wire for signal (+) and one jacketed wire for ground (-) connections.

See photos below.

DT667 6/13/2021

ARTA Measurement interface Part 2

Input Signal Attenuator

DT667 created an "input signal attenuator" circuit that allows for fine tuning of the ESI Juli@ soundcard output signal as it enters the DUT/AMP.

The internal signal generator in the ARTA freeware program allows for adjusting the output signal in 1dB steps. DT667 would like a more precise output voltage across the 8 ohm 100 watt load resistor that is connected to the DUT/AMP, so this attenuator circuit is used.

See photos below.

DT 667 6/13/2021

ARTA Measurement Interface Part 3

Output Signal Attenuator

DT667 created a "output signal attenuator" interface that can be used with ARTA software and a high quality 192KHz/24 bit soundcard like the ESI Juli@ or similar for tube amp benchmarking : THD, Bandwidth, Phase, etc.

The interface will attenuate the voltage from the DUT/AMP into the soundcard input by a factor of 2:1 or 10:1 depending on the position of a SPST resistor shorting switch.

The idea is to create a low Z resistor divider to protect the soundcard input from too much voltage and for impedance matching.

DT667 has used this sort of soundcard attenuation circuit at up to 3W power output.

DT667 also owns Virtins soundcard test probes which have zener diode protection. DT667 found that the zener diode clamps in the Virtins probes can clip the input signal into the soundcard and cause unreliable THD readings at higher power output.

See photos below for basic circuit layout.