DIY Audio Project Ideas and Work in Progress

Author: Dmitry Nizhegorodov ( My other projects and articles

1.   Composite Tube Models

This is work-in-progress. Some of the pages mentioned here are preliminary, drafts, etc. So far there is a constantly-expanding page introducing the main idea of composite models: composite-triode-models.htm, the results on the nature of 120Hz hum in DHT amplification stages: filament-ac-freq.htm and filament-ac-harmonic.htm, use of parallel triodes to simulate and neutralize DHT hum: parallel-triodes.htm, dht-filament-hum-cancel.htm. Future work: clipping characteristics of DC DHT, AC DHT and heated triodes compared, analytical composite triode models in more details.

There is also an application of composite modeling here: 6f5p-set.htm#parallel_connections

2.   SPICE Simulation

Simulation of SE-transformer-loaded PP amplifier. This is a lot like Decware Torii

Collect various SPICE simulattion tricks and techniques. done

Study various topologies around the theme of Direct Reactance Drive amplfier. done

Show with SPICE that a typical multi-way speaker is a difficult load for a SET amp. part 1 is done

Analyze Ultrapath Line Stage. Done.

Study Harmonic Cancellation in 6c45pi / 6p14p SET

How to plot the results of FOURIER in parametric SPICE runs. done, here

Distortion patterns as XY mode Lissajou figures. done, here

How Miller effect creeps through volume controls. 100K pots and tube amps. Also: passive preamps and interconnects.

Strange Algebra of SETs. This algebra of distortion propagation through SET components reveals why listening impressions differ so much. A + B != B + A. A + B != - (-A + -B). Harmonic cancellation, etc.

Tube guitar effects in SPICE. Converting a Heathkit A151 into a gutar FX.

Can we hear OPT core hysteresis distortion? Can we see it in SPICE?

SPICEing a symmetrical PP with adjustable balancing.

Speakers as filters.

Time alignment and time delays in 2-way sustem with low frequency equalization SPICEd.

3.   Amplifiers

Low power 6p14p SET. Done: Flea-Power 6p14p SET Amplifier. Also: all-russian-parts version.

MaggieMug: Magnepan tube crossover. Done: maggie-mug.htm

ECC99 into 6c33c SET. Done: ecc99-6c33c-se.htm.

A good SET Linestage must have a polarity switch and loading taps

Linestage Matrix: properties of various linestage topologies.

Direct Coupled Power-Tower Amp.

DHT hum elimination in a Welborne Moondog. Over a dozen solutions tried. Draft: hum-moondog.htm

Yet another opamp-less tube DAC experience.

A "variable-ended" amp.

4.   Speakers

Open Baffle Line Array Speakers

My wide-range sub woofers.

Testing drivers for distortion using Lissajou (XY mode).

Simulating Lowther PM6A in various horn enclosures using Hornresp.

5.   Tools

DIY Curve tracer plate-curve-tracer-acpc.htm

My indispensable relay AB ABX box. Mainly Done!

6.   Guitar projects

Subminiature tube flea-power guitar amps. In progress: submini-vibro-reverb.htm

Flea-power guitar amp in Silvertone radio case. In progress: svt700.htm

7.   Software, simulation

Triode simulator in Java

8.   Analog sources

Tuning my Thorens 160

Zero-feedback tube phono stage: improving Heathkit SA2's preamp circuit.

9.   Wild Ideas and Concepts

Creative bridging of single-ended amplifiers. In progress: creative-set-bridging.htm

Distributed switching: relay networks in high-end audio.

Two way DAC with digital time delay for two way sound reproduction system.

Spectrum-controlled variable-feedback, variable-symmetry amplifier.

Author: Dmitry Nizhegorodov ( My other projects and articles