Merlot

Merlot-entry level valve audio.

The build criteria for the Merlot valve amplifier was to construct a simple and excellent sounding valve amplifier from inexpensive parts. But this amplifier had to set an example of what can be expected from any valve amplifier.

Merlot's goal was to demonstrate to those listening to their first valve amplifier that, in a number of areas of quality audio, valve amplifiers can challenge, at a musical level, not only solid state amplifiers but inexpensive commercial designs. The design is single end (SE) and ultra linear (UL) with diode rectification.

Merlot uses two common valves: the 6N1P and KT88. The output valve can be replaced by a number of other valves: EL34, 5881, 6550, 6L6, 6V6 etc. I encourage "tube rolling". Feel free to replace the two output valves. Very different timbres and tonal balances can be obtained by tube rolling. This amplifier supports that practice.

If Merlot looks like this amplifier was hand built completely from scratch that is because it is. From the very solid Mirbeu timber base to hand assembled modules. There are no printed cct. brds. or commercially prepared modules Incorporated in construction. There is no additional wire used in the hand made modules, on component wires joined to other components. This is a technique I have used extensively here called component-2-component wiring. Fewer solder joints and less "hook-up" wire than point-to-point wiring. Individual modules are available.

retro-thermionic attempts to bring back some of the look and sound of early valve amplifiers. The use of heavy timbers, metal, large transformers and protruding valves is purposely done to produce a retro look and to reproduce music as it was meant to sound. Like music.

The sound of the Merlot is excellent mid-range tones, clean clear highs extending to 46khz and a balanced bass down to 35hz. Merlot's greatest strengths lay in its mid-range. Human voice and acoustic instruments are rended with great transparency, natural tone, real depth and immediacy. Output is 6.5W RMS per channel so efficient speakers are required.

This amplifier can be ordered and built with minor modifications should you require. Other models include: Cabernet and Shiraz which use more expensive parts but still the same retro look, more refind and detailed sound. These amplifiers will feature on this page.

Merlot - rear panel

The rear of the Merlot amplifier carries all connections. These include: two switchable RCA inputs, speaker binding posts which will take spades, banana plugs or captured wire, power cord outlet, fuse and on/off switch. The Merlot can be configured for 11oV. A standby switch is atop the the amplifier. This allows you to switch off the high tension but leave the heaters on for immediate listening, during short breaks. This saves power and stops cathode stripping by applying the HT after the tubes have warmed.

Merlot with JJ KT88 Blue Glass

A number of different power valves can be fitted to the Merlot. It is one of the great strengths of an open valve amplifier, that different tubes can be "rolled" for different tonal balances. In this instance a matched pair of JJ KT88 Blue Glass have been fitted. This has increased the low end weight and brought the mid-range forward slightly. Apart from the different tonality the Blue Glassed JJs look stunning. Many other valves and speciality tubes can be rolled into the one basic power amp. Have a favourite power tube which has the same pin outs and specs as a common KT88? Then roll it into a Merlot. Plug and play-your way!

Merlot - Black Top and Black Sable EL34

This is the first of the Merlot range I constructed. In this build all switches, controls and connections are on the top plate. The paint used is an epoxy enamul and forms a tough and textured finish. Modular design was developed in this first "proof of concept" build. Once again component-2-component construction was used in forming the modules.

This amplifier diplays all the mid-range fine grain clarity of the second build (above). A number of different valves can replace the EL34s used in this amplifier. Matched Black Sable EL34s are installed in the amplifier above.

Merlot - Black Top EL34

With the Merlot - Black Top build the valve sockets were recessed into the top plate.Therefore valves with large basses e.g. KT88 could not be installed. This issue has been corrected with the second build and now all bases sizes can be accommodated. Fortunately the amplifier sounded excellent with the EL34 Back Sables. This amplifier has also delivered excellent music with 6V6 Black Glass (original Australian made valves).

Merlot - Diode Rectification Module

As with all retro-thermionic amplifier sections each part is modularised but no module contains any wire other than the component wire. The Diode Rectification Module is a full wave rectifier employing the centre tap of the large power transformer. A large 10H choke is also used as part of the rectifying and power smoothing network. When a large choke is used to reduce hum and noise in the amplifier smaller filtering capacitors can be used. Smaller power capacitors produce a better detailed mid-range this is one of the better traits of a SE UL design.

Wiring between modules is of the free style method. Copper hook-up wire runs the shortest and safest path to the next module. Internal wiring is loosely banded together for safety and to ensure minimum cross talk. By using the shortest wiring path, total signal path length is kept to a minimum.

I can provide these rectifier modules, or any other of the retro-thermionic modules, for the individual who would like to assemble their own valve amp. E-mail me for a quote.

Twinings Tea Box Preamp with Remote PS

The Twinings Tea Box preamp is very much retro-thermionic. Always the mix of timber, metal and valves presents, not only a strong retro feel and unique images but very much a desire to get back to listening to good music the way it was meant to be. Controlled resonance qualities in natural materials can add a certain earthiness or natural tone often amiss in modern, commercial audio equipment. One of retro-thermionic's goals is to construct audio components in a novel and organic way, most often using timber, Bakelite or metal in audio component construction.

The inexpensive Twinings Tea Box provides a natural looking enclosure in which to construct a preamplifier using high-end and carefully chosen components. To further add to the lofty concept of the build a remote, valve rectified, power supply was added. In the image you can see not only was valve rectification and enclosed choke filtering used but a rare Australian made 5Y3 rectifier valve was also employed.

The chassis, on which the remote power supply is constructed, is die-cast Al. Hammond enclosed power transformer and 10H choke sits atop. Other electronics are housed beneath the solid chassis, which, like the preamp itself, reside on solid brass cones. Connection between preamp and associated power supply is via a high voltaqge short cord and XLR plug.

The Jensen copper, paper and oil capacitors and associated components (including the enclosures) make this a unique sounding andlooking preamplifier. Either coupled with a solid state power amplifier or a valve power amplifier this original almost conceptional preamplifier offers an exceptionally unique insight into electronics and audio reproduction equipment not seen in commercial units. And for the engineers amounsgt us the distortion figures fall below 0.05%. The musical rating figures: 99+. Listen and be convinced.