"Cadence" - SRPP 6SN7 Preamp

 

After building yet another SRPP 6SN7 preamp for another, who had his onw tubes, I build this one to used the spare Psvane Grant Fidelity 6SN7 Spheres I had. A few changes from the previous one but similarities to others. Big difference is the colour - Hammertone Copper. Other preamps I have used the same colour but not with the Hammond Wood chassis. 

Similar to others with with the Danish Jensen copper paper and oil output caps. Before discontinued they were quite expensive. Other similarities are the final filter cap in the preamp which is a Russian PIO 4uf with a Russian 0.1uf snubber. Fine silver plated hookup wire and Alps Blue Velvet pot round it off with the 4oz solid brass gold plated knob. This time resin tube sockets and not the usual ceramic. Cheeks are treated with a high grade finishing oil which dries to a hard glossy wax finish while lifting the grain. Nice.

Using an earlier PS which is choked and relies on an external 24VAC 1A wall wart I found the sound quite a jump up from all other preamps built with the same tubes. Also in this build I used 1W carbon film resistors except the grid resistor which is metal film. There is only three resistors in each channel and the two main Rs in the signal path are the carbon film. Ck is a low ESR type. Is this the carbon Rs the secret to the better sound or is the expensive caps? Whatever bass has a whole new depth and texture, mids crazily engaging and textured and treble super smooth and sweet.

This preamp was built to sell and move on the spheres. Not sure that is going to happen any more.

"Essence" - 6SN7 Preamp

 

Not the first of the 6SN7 preamps I have built but his one is not for me. And not the first in this hammertone blue. This is a commission job and the future owner has his own, fine, Psvane 6SN7s. Pictured here with my Psvane Grant Fidelity Spheres (expensive) for testing (and a lot of enjoyable listening). Two selectable inputs selected from the front switch and two outputs. One output for an active sub woofer. 

Under the bonnet are standard metal film resistors, a 24 step stepper attenuator, low ESR cathode bypass cap and my fav. 0.47uf Russian Military paper-in-oil output caps. The knob is 4oz of brass and gold plated. Combined with the stepper has a good solid feel. The heavy weight knob also helps with resonance control in the attenuator and chassis. From past builds you will recognize the Hammond wood cheek chassis. Paint is epoxy enamel with an acid etch primer. Always comes up well when the primer is used. 

The sound is what I have come to expect from similar builds with these tubes - balanced, clean and clear with detailed and warm midrange. Different tubes will have slightly different listening results but should stay very much in the enjoyable zone. PS is external with electronically filtered HT and regulated filament voltage. The preamp is absolutely dead quiet. The new owner will love this preamp. He should like the colour, he picked it.