Another 45 amp with C3g driver

Here is another 45 amp. It seems like I like the sound of the 45 very much indeed.

This is the “Shiny Eyes” 45-C3g DHT amplifier, built with care and to provide a rewarding sound. This is an audiophile amplifier and it is not for everyone. It delivers up to 2W output. These 2W sound bigger than it shows. It is indeed a 2,000,000 microWatts. It is meant to be used with high sensitivity speakers. I listened to its sound using recently built TangBand 1772-W8 full range driver speakers. These are 96 dB sensitivity and fills the 300sqft room. For concert levels,a 100dB+ speakers are required.

The amplifier has 4 and 8 ohms outputs  through a switch and Cardas binding posts.  The output transformer are James 6123HS and the interstage transformers  are  Lundahl LL2762. The 45 tubes filaments power is supplied through a Coleman regulator. Therefore, it is a need to adjust the filaments every time the tubes are  replaced. A 5V high quality Simpson meter is used for this purpose.

The power supply has a separate enclosure. The high voltage uses a Hammond 278X, high quality Chicago Standard Chokes 10H/180mA chokes and 6AX4 tube rectifiers. The setup is choke input for a better sounding amp. The high voltage delivered to the amp is measured and shown on a nice Simpson 500VDC panel meter. There are 3 raw, well filtered and regulated DC supplies : two for the 45 filaments and the third for the C3g filaments. The power is supplied to the main amp through an umbilical cord that carries only DC. The connector is Amphenol military grade. This way the AC is kept away from the main amp and the amplifier is dead quiet on my 96dB speakers.

All the components are high quality and audio grade where needed, such as Nichicon KG, Takman, Mills, Elna Cerafine, Clarity caps, ASC Oil caps, Mundorf Mlytics.

The amplifier shows a dominant 2nd Harmonic that confers the absolute astonishing sound of a well praised DHT. One of the picture shows the harmonics and THD and one can observe that the THD superimposes almost perfectly on the 2nd harmonic. The maximum THD is 3.8% at 2W ( naturally second harmonic), the frequency response is better than 20-20KHz +/-1dB, the input sensitivity is 0.8Vrms for 2W output, the input impedance is 51Kohms and the damping factor is 4 on 8 ohms.

The enclosures are hand made using American cheery nicely finish with 4 coats of Oil and Urethane, and sanded aluminum 1/8″ top plates.

This is a well built amp to last for a long time.( more of my work can be seen on simplepleasuretubeamps). I am very fond of the sound of the 45 tube and therefore I’ve built a few 45 amps and always pleased with the results.

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