How I Tweaked my full range BL horn speakers

Almost 4 years after the construction of my Back Loaded Horn speakers, I decided tweaked them adding tractrix horns using compression drivers for the high frequencies.
Searching the web and asking friends who had already experimented with such drivers, I decided to implement a structure based on a tractrix horn using an 1" (inch) High Frequency compression driver.
For this purpose I chose a cheap but very good European driver the BMS 4524. Another reason why I chose the particular driver was the low cost which is around 80 euro / pair , so I can comfortably experiment without wasting a lot of money...

A single-ended direct heated triode tube power amp design, by costas sarris

Direct heated triode power output tubes are really interesting. Since September 2008 I've been working in a new project regarding a single ended triode tube power amp using the 811A vacuum tube. Actually it is a project with a long process of experimentation.

The 811A vacuum tube it is a power triode capable to output 10 - 15 Watts in a single ended class A2 configuration, in a three stages circuit using interstage transformer in the driving stage.

It's all about a double project. At first I built a prototype amp using the SV811-3 tube. Afterwards I built another one using the 811A tube in order to offer it as a gift to my friend Scott.

When I started constructing my first DIY horn loudspeakers, I had to decide what material to use for building the loudspeaker enclosures. It is well known that the materials a loudspeaker cabinet is made from can affect to the sound quality produced by the speaker.
A kind of "Coloured sound" is the result due to the resonance of the cabinet walls. This subject is often discussed among speaker manufactures, and there are lots of opinions if the material of the cabinet should contribute to the sound or not.

For my DIY horn loudspeakers I choose the FE206E driver by Fostex. Fostex recommended the use of plywood, that's why I decided to learn more about this material, and its sound insulation and damping characteristics.
Although I am not an expert in building loudspeakers I know that for building a well damped speaker cabinet there is a combination of strength, stiffness, surface stability and the sound insulation of the material.

DIY single ended amplifier by Christos Spathopoulos

Even though 6L6 tube is used primary in guitar vacuum tube amplifiers, many manufacturers use this tube in audiophile designs. I decided to build this small single ended amplifier based on 6L6 vacuum tube using a classic three stage single ended design.
The plate voltage is about 320 Volts and the output stage is a classic single-ended cathode follower. Output transformer is 4500 ohms and is set for 8 ohm speakers. We chose this design for one reason : Wiring this tube as tetrode we achieve the greater possible amplification as a result of higher grid transconductance.
Click to the picture below to see more photos and the Schematic.

DIY tube 807 amplifier by costas sarris

In the summer of 2002 I decided to build a pair of mono block parallel single ended DIY tube amps, using the 807 tube. Actually, that was my third DIY tube amplifier project. It all started with my decision to use the less known tube 807 , a tetrode whose features and sounds I was well aware of, from a specific DIY project (with one tube per channel wired in triode) made by Christos Spathopoulos. Christos’ tube 807 amp played very smoothly in the whole spectrum (perhaps the best sound I had heard until then ) but, unfortunately, it lacked power.
After we discussed my idea with Giannis and Christos Spathopoulos we focused to build a tube amp with two parallel 807's per channel in a cathode follower connection, wired in tetrode - class A, using negative voltage in screen, based to the characteristics according to RCA and SCT...

EL84 single ended Tube amp DIY project by costas sarris (2002)

This project based on Decware EL84 Zen Amp

Making a low power single ended amplifier has always been in my designing plans. Obviously such a construction requires the appropriate speakers, particularly horn type designs, so that the output of the amp can reach an efficiency satisfying level.
Once at a certain point, I came across the designs of the Decware SE EL84 Zen amp, which had quite good reviews among the tube amps DIY and Single Ended tube amp builders.

DIY horn loudspeaker project by costas sarris

In February 2006 after I had completed the construction of my dual mono PSE 807, me and George Filippou decided to build a pair of horn speakers using a full range driver in a back loaded horn design, which could easily be driven by the 807 single ended & 811A tube amps, we had designed. We choose a design by FOSTEX with the full range unit driver FE206E which has been designed (according to the manufacturer) for use in back loaded horn type enclosures.

Although bass reflex projects have been presented by some manufacturers this driver is generally unsuitable for bass reflex enclosures because of its over dumping characteristics.

Push Pull 6550 DIY audio tube amps by costas sarris (1995)

The idea of building a DIY audio vacuum tube amplifier based on high-quality materials begins in the early 90's. Initially had to answer the question "Classic Push Pull or a Single ended amp ?" So starting the design somewhere in 1994 I decided to design οn a blank piece of paper, a pair of monoblocks push pull tube amps with a power supply in a separate chassis which would not use solid materials but rectifier tubes.

In the first photo appears the two channels of my tube amps DIY design which consists of 2 mono blocks with a tube power supply in a separate chassis.