Friday, October 9, 2015

A custom built 10 Squared featuring 27 sources for parts including nickel interstage and output transformers from Dave Slagle.

Wednesday, October 7, 2015

Breadboarding a new flywheel B+ power supply for a 300B build...stay tuned!

Monday, August 31, 2015

Here's an amplifier that I build back in the day based on an article that appeared in Issue #3 of Sound Practices entitled "A 5 Watt 6BX7GT Triode Amplifier" by Ed Warden.  The main differences here are: (1) this is a stereo amp whereas Ed built mono blocks and (2) this amp has vacuum tube rectification as opposed to solid state.

The power transformer is a robust unit from Allied Electronics and the vacuum tube rectifier is a 5V4.  There are separate LC filters comprised of Hammond chokes and Nichicon capacitors for each channel.

The input tubes are 6SL7WGTs and the the output tubes are 6BX7GTs, obviously.

The output transformers are metal cased units - donors from a hi-end vintage integrated amp.

All of the coupling capacitors are Mundorf Silver and Oil - somewhere in the neighborhood of $250 worth themselves.  The RCA jacks are Vampire and the binding posts are 5-way types.  All of the tube sockets are ceramic.  The balance of parts are well known quality types.

This stereo amplifier is a solid 5 watts - all triode, push-pull (PP) watts that is and, as a result, works well with a wide variety of speakers.

The amplifier is built on a chassis measuring 16 inches wide by 8 inches deep by 3 inches tall.  Overall height is approximately 7 inches.  It weighs 13 pounds.

The guy that owns it just traded up to a much more expensive amplifier from me, so I am helping him with the sale.  I just ran the amp across the bench and through my system - it checks out fine.  He is asking $750 shipped in the US.

Feel free to call me at (513) 417-0130 should you have any additional questions.

Friday, August 28, 2015

Below is a 10Y DHT line stage prototype that I recently built.  It features a current sourced, shunt regulated B+ power supply and Rod Coleman filament regulators for the 10Ys.  Additionally, the 80% nickel output transformers are from Dave Slagle.

Ultra Fi Continuous Contact Damping Cables Mentioned on today!

Here's a link: 6Moons Newsroom

Studio Ultra Fi


Studio Ultra Fi was constructed in the lower level of my home and comprises framed construction set off from concrete walls and a floor. The drywall is green glued to the framing members on all sides and the ceiling. Beneath the side walls is fiberglass insulation with the paper backing alternated every other stud. This forms somewhat of an alternating membrane trapping arrangement beneath the drywall. In addition, the density of this fiberglass is varied and increased from the center of the side and front walls from R-19 in the middle to R-36 in the corners. This accounts for the fact that bass frequencies tend to pile up in corners and go through drywall.

The back wall behind the listening position has a membrane bass trap beneath and built into the drywall below the ceiling and above the double door entryway that is double stuffed with R-36. This designed to address slap echo between the front and back walls.

The ceiling is all R-36 suspended between the floor joists above. The soffits running along the junctions of the side walls and the ceiling are lightly and selectively stuffed to form additional brass traps and house lighting. In addition, the soffits are angled in the front corners to add additional trapping and further house additional lighting, again accounting for the fact that bass frequencies tend to pile up in junctions of room boundaries.

The carpeting and the padding below was also selected for its acoustic properties as well as its appearance as the floor forms a first reflection point between the loudspeakers and the listening position.

The front wall contains four highly modified and cryogenically treated outlets in plastic boxes with selected and dampened wall plates, all on dedicated circuits, run using double Romex.

The lighting is worthy of additional mention as it may be used to alter the mood and feel of the Studio while listening. In all, they are four means of lighting the Studio including three main zones, the lighting in which may be varied in intensity using dimmers that are also on their own dedicated circuits. The first zone comprises two can lights located on the angled portions of the soffit between the side and front walls. These cans may be tiled and directed to vary the amount of light that is spilt on the front wall and/or the floor. Halogen spots are used in these cans. The second zone comprises four can lights located pretty well behind and just in front of the loudspeakers. These cans have full spectrum flood light bulbs. The third section also comprises four can lights containing halogen spots somewhat straddling the listening sofa in front and behind.

Further, and as configured in its horizontal orientation, the Apple Cinema computer monitor may be used to spill light upward and onto the front wall highlighting the painting on the floor wall.

In use, the monitor is seldom employed for lighting purposes.

Typically, one of two approaches are selected and varied in intensity to light the Studio. The first is to use the second aforementioned zone and that is what is shown in the photos. This gives a warm natural hue that accentuates the various shades of tan and the wood tones in the room, bringing out the warm red of the listening sofa and ottoman. Very relaxing after a long hard day.

The second is to select the first and third zones. Unfortunately, this selection of lighting didn't photograph particularly well and is therefore not shown in the photos. This lighting gives an expansive, modern, metropolitan feel to the Studio and is the one that is used more often than not. This is the de facto choice for working on the computer, reading or just hanging out with my wife while listening.


The acrylic and oil on canvas painting hanging on the front wall of Studio Ultra Fi was commissioned from renowned sculptor Scott Naylor - a good friend and fellow audio enthusiast. More than 1,000 sculptures from Naylor may be found throughout the Nation and although Naylor typically sculpts in bronze, he's likewise an accomplished artist and, in this particular instance, painter.

In this commission, Naylor paints in a style not unlike that of Wassily Kandinsky (1866-1944) being influenced by the Jazz often played in the Studio. In addition to capturing the elemental colors found in the Studio, Naylor makes use of a background coloring technique that allows the painting to change based on its lighting taking on different - Pace, Rhythm, and Lighting - thereby developing different looks, moods, and feels with the selection of the lighting used and music playing in Studio Ultra Fi.


The two first reflection point panels seen on the walls adjacent the speakers comprise a framework of 3/4" thick clear white pine to which furring strips and gussets are added. The furring strips and gussets support 2" thick Roxul 60 and space the Roxul 3/4" off the wall in use.

The first reflection point panels were are covered in wall colored fabric that was stretched and stapled around the periphery of the frame.

The four bass traps located at the back of the room and seen on the side walls were constructed in like manner.

The four bass traps located on the back wall were constructed in the same manner save two important differences. The first difference is that the framework was sized to accept two layers of the Roxul, making the dampening material in the traps 4" thick. The second is that a sheet of kraft paper was placed over the front of the frame prior to traps being covered in fabric. This forms what is commonly referred to as a limp membrane absorber. These two differences extend the lowest frequency of efficacy these panels compared to the others by more than an octave.


The ceiling panels comprise a framework of clear white pine to which an 1/8" panel of masonite is fitted. The structure was then painted white to match the ceiling. The framework and the panel are used to support a 2" thickness of Roxul 60 wrapped in white acoustically transparent cloth. When suspended from the ceiling at the appropriate angle, these panels form a membrane bass trap from the front and an absorber to reflections off the ceiling on the back.

More to come...
Here's one of the Darling amplifiers I built back in November: