Input Transformer

Now with headphone output impedance of 8, 32, and 300 ohms to pair with an extended range of headphones.

The name AGARTHA is used to describe a legendary city in the center of the Earth. The ampsandsound AGARTHA brings the legendary 300B to personal audio. We chose the 300B for its long history as the king of triodes. Combining a single gain stage, zero feedback, and careful attention to grounding techniques we can use a 300B with headphones without hum or noise. For those with headphone, horns, or single driver speakers who are seeking audio nirvana, the AGARTHA is built with exacting attention to parts selection and implementation. 

The AGARTHA tube amplifier pairs a 6SL7 tube for the front end with SS rectification enabling great transient peeks, fast/lively presentation and ultra-quiet operation. The AGARTHA uses direct-heated triodes with zero feedback providing the classic single-ended sound so widely loved.

Typical of all ampsandsound amplifiers, the power supply is massive and combined with a generous choke it yields our trademark low noise; less than 3mv at idle, and stable output of 5 watts RMS into an 8ohm load and 1watt into a 32ohm headphone. Frequency response is 12hz to 30hz at 1 watts, 1-db. Output iron has been carefully selected to reduce distortion and increase frequency response and, of course, we also use our 5% capacitors and 2% resistors.

The motivation of the AGARTHA is to provide access to the wide availability of NOS tubes and give the warm mid-range bloom that is at the heart of single-ended direct-heated triode designs. Tube set included.

Input Sensitivity: 840mV RMS for full power
Max Power: 5 watts RMS into 8 ohms
Max Power: 1.5 watts RMS into 32 ohms
Noise: 760 uV as measured from 8 ohm tap
Noise: 660 uV as measured from 32 ohm tap
Power Bandwidth 20hz @ -.5db down to 20Khz @ -2db down as measured from 8 ohm Speaker tap measured at 1 Watt RMS
Power Bandwidth 20hz @ -.5db down to 20Khz @ -4db down as measured from 32 ohm Headphone tap measured at 200mW RMS