Again using up expensive parts on hand another SE UL tube amp. This time using a tweaked schematic which favors EL34s. I have a number of brands of EL34s on hand including:- Svetalan, Siemens, Black Sable, Tung-Sol and Electro Harmonix. Some quad matched sets like the Tang-Sol and Black Sables. With a mix of carbon and metal film resistors, mustard caps as snubbers on Ck and Jensen copper foil paper and oil inter-stage caps this is a real mixed build. Once more the whole idea is to use up what is on hand. KT88s can also be rolled for a different sonic presentation.
On hand I had the big Hammond 600V 200mA power tranni, open frame Edcor OPTs (under the bonnet), the wood base and top plate, inter-stage caps most resistors, ceramic and resin tube sockets, tubes and all components for the SS rectification cct. and smoothing caps. The PS is a triple Pi config but this time no choke. CRCRCRC with 100uf caps and 330ohm 5W Rs has produced an extremely quiet amp with only 0.9mV of noise. Total caps is 750uf.
The base is Australian Spotted Gum and after being sanded smooth and oiled was re-prepped with "0000" steel wool and re-oiled. The timber looks rich and is extremely smooth. The top plate is sprayed with Hammertone epoxy enamel after being sanded and etch primed. The finish looks lush and the Hammertone hides any dust particles or blemishes. The top plate is 2mm Al and the Tranni is isolation mounted to it to reduce vibration to the tubes.
Cat5 solid core wire for the audio path and HT is delivered with either twisted pairs of Cat5 or heavier wire. There is no shielded wire and the audio is delivered to the 6N1P via Cat5 twisted pair. Where I found the sound of the KT88 amp - Toccata - very open with a huge sound stage this amp sounds a solid and grounded again with a large sound stage. Once more a very transparent earthy presentation and now with the Siemens tubes in place a cleaner open sound. Bass is full on and extends down to 30hZ.
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