Friday, December 31, 2010

Build amplifier

Design notes (specifications):
- valve preamp (such as Octave's Phono Modul) or passive preamp (such as Music First Audio's Classic Preamplifier)
- built-in preamplifier suitable for various analog and digital sources, w. auto-detection and auto-protection - minimum 2, upgradeable to many (turntable, tape, CD/DVD/SACD, video, tuner/AUX, MIC, USB, HDMI, Ipod, LAN/Wireless etc.), and auto-switch-able IN/OUT paths:
  • analog IN: balanced (XLR) +0 dB
  • analog IN: unbalanced (RCA) +6 dB
  • digital IN: 24bit / 96kHz
  • digital IN: balanced 110 ohm (XLR) AES / SPDIF (??!?)
  • digital IN: coaxial (RCA) 75 ohm
  • analog OUT: balanced variable (XLR) +12dBU (??!?)
  • analog OUT: unbalanced variable (RCA) +6dBU (??!?)
  • analog OUT: unbalanced fixed (RCA) +6dBU (??!?)
  • digital OUT: SPDIF (passive)
  • digital OUT: HDMI (passive)
  • digital OUT: optical (passive)

- D/A-converter:
  • 24bit / 96 kHz (upgradeable to 96 bit / 192 KHz)
  • sample rates: 44.1 / 48 / 96 KHz
  • THD: less than 0.001 dB
  • S/N ratio: over 110 dB

- MOSFET in Zen amp by Nelson Pass, or similar:
  • impedance: 4-8 ohms
  • power: 50-75 W / mono-block channel, in stereo (upgradeable to 5.1)
  • frequency: 20 Hz - 50 kHz
  • dynamics: 120 dB
  • S/N ratio: over 110 dB
  • THD: less than 0.001 dB
  • analog OUT: speakers 4-8 ohms, 50-75 W / mono-block channel, 2/5.1 channel
  • analog OUT: headphones (Class A MOSFET design), ± 3.5V / 400mW / 32 ohms

- built-in 1-scale FM radio w. RDS, at least 50 preset stations
- built in internet radio
- built-in controls for volume, bass/treble, DSP, multiple EQ (5-10 bands)
- memory presets for controls, individually on radio station and/or record
- support for AudioTag and other online video, music and lyrics databases to get informations related to the record played (freeDB, CDDB, MusicBrainz, IMDB, MLDb, / other music databases etc.)
- remote control (IR + RF, programmable, universal)
- web server for setup (linux)
- multi-color display panel, more like a monitor


Nelson Pass (Pass Labs):

DIY Audio Projects - DIY Hi-Fi for Audiophiles:

Ralph Stens - diy projects for audio devices (preamplifier, amplifier, turntable, loud speakers), as well as links to other sites
Elliott Sound Products - Professional results for the Do-It-Yourself enthusiast

Wednesday, December 22, 2010

Build speakers and acoustic tips

After reading many info on custom build speaker setup (just reading!), if I ever start the path of building diy speakers for stereo listening, I'd start with these specifications:
  • room: 400 x 300 x 250 (L x W x H)
  • frequency responce: 50 Hz - 35 kHz, +/- 3dB
  • nominal power: at least 50 W (RMS) / 4-8 ohms
  • sensitivity/efficiency: min. 90 dB / 1W/m
I choose the following:
- 2-way design
- 2 x bass Vifa MG18 (DIN 60 W, 86.5 dB, 8 ohms)
- tweeter Vifa XT25 (flat 1kHz to 40kHz, DIN 140W, 91.5 dB, 4 ohms)
Note: it can be of interest:

BassBox Pro - a state-of-the-art speaker enclosure design program
Building a 3 Way Active Loudspeaker - The information is meant to give you more insight when you think of going active

Repair damaged wood panels on speakers (probably account needed to see pictures):
Evaluation Myths Busted - an article about Subjectivity vs objectivity

Technical Studies, by Music and Design
SigTech AEC-1000 Room Acoustics Equalizer, for a better stereo experience

Playing with room acoustics, by Mark Wheeler

Vinyl vs. CD - Huge discovery! - forum post by Steve Deckert

Speakers gallery:

Wednesday, December 1, 2010

Path to the sound of perfection

I start this post with the idea of looking for what I call "path to the sound of perfection". It's what I am looking for in audio (maybe video too), with the minimum of investment versus the results. The record (LP/CD/DVD/PC) should be played as close as possible to the stage/studio recording, having the least influences of artificial compensation of electronics or other parts used. I should take into account that many ideal conditions for a "perfect reproduction of sound" can't be meet, at least when the audition room is the living room in a flat, having children/family/neighbors etc. That makes the "path to the sound of perfection" limited to the conditions met in the real world and, with that in mind, as close as possible to the ideal conditions.

The budget for this setup may change in time, as I acquire more experience and my exigency increase. The target is to make the setup easy and simple (to build), quality and durability included. For life.

The ideal setup would be: playing everything from a music sever (computer, network or just a hard drive). As a general layout and for consistency, the following rules applies to all audio/video equipment:
- turn on/off instantly (less than 1 sec.)
- completely modular, so it can be upgraded or add complexity with easy
- the possibility to be powered by a PC source (5V / 12V), using computer plugs (isolated, if needed)
- auto-diagnoses on start up and alerts when "out of parameters"
- monitoring of temperature via sensors
- protections for under/over voltage/current and wrong plugs