Tuesday, September 11, 2012

retro-34UL power amp

In an effort to use-up so many spare parts I have I put together another EL34/KT88 amp. Part of the inspiration to build the amp came about when I was given four 1996 NOS Svetlana EL34s. These bare the old Svatlana logo. Also I had dismantled a bread board amp which had a large power tranni and choke which were perfect for this build.

The base is Australian Spotted Gum and the power tranni and choke are Hammond. The OPTs are Edcor 15W open frame types, reside in the base and are shock mounted. The feet are filled with lead sinkers for resonance control. A CLCRC filter network ensures the amp performs dead quietly and has an extremely high head room. Frequency response is to 40Khz and power is 5W RMS into 8ohms. Russian paper in oil caps are used in the inter-stage and bipolar caps and low ESR caps are used in the cathode bypass. Silver plated wire-wrap wire hooks up the gold plated RCAs to the nearby 6N1P and connects  the secondary of the OPTs to the binding post.

The paint work is epoxy enamel on 2mm high grade Al plate. Silver solder is use in the driver stage. Component-2-componet wiring is used to ensure signal path length is kept to a minimum. There is no shielded wire or PCBs to degrade the sound. This is a fast amp with a huge sound stage and a rich lush EL34 sound.

This amp has been built to sell.

Wednesday, September 5, 2012

Fostex FE206En drivers in dual bass chamber box

I had the boxes made some years back with no idea what I was to do with them. When I went back to 2 Channel theater with a 3.5W 6EM7 integrated amp (Paris) I knew they would be perfect around my new 46" LED TV and Oppo BDP-93 blue ray player. The finish is satin black stipple and the grills are held in place with four rare earth button magnets. Easy to pop on and off. The stipple effect was produced with a roller going over the fresh paint a number of times as it dried. The drivers huge magnets have bitumanised Al foil dampening attached and the internal wiring is two stands of lightly twisted wire wrap wire to each binding post.

The top chamber is lined (but not stuffed) with Dacron but the bottom chamber is empty. There is no Xover in these full range speakers. Efficiency is 96db at 8ohms impedance so they work well with flea power tube amps. Sitting higher than the tweeter (wizzer cone) the sound is quite natural with just a touch of forwardness in the mid-range. The speakers not only look stunning they sound excellent for a $500 spend.