The High Fidelity Voights

By Thomas H. Eberhard
13 Feb 1997

Introduction

This little wonder gives bass down to about 40 Hz. I bought four of them very cheaply with the rather strange configuration of 2 modified Philips dome tweeters and one Altec Lansing 4" wide range driver in each. I have tried them with a variety of 5-6.5" drivers and they sound good as long as high Qts is avoided. Probably even a 8" unit can be shoe horned into service but this I have not tried yet.

The drawings is as published in the Danish High Fidelity in 1972 Fig. 1. The drawing. In those days damping and such matters was largely trial and error and no real measurement or theories to give staring points. The figure shows the frequency response I measured some years ago. With some glassfiber in the chamber and in the first section of the pipe. I threw away all four cabinets due to space restrictions some years ago.

The drawings is like the original the pipes is made of 16 mm chipboard the damping material are two pieces of rockwool. One 30 mm thick in the chamber at the backwall and one at the bottom bend 20x20x50 mm.

I used a Philips AD 70631 M 6.5" double cone fullrange driver and measured the response with a Technics SH-8000 (the test tone is warbled by 8 Hz) Fig. 2. Nearfield response.

I will build new cabinet to get some answers to the following:

• How to damp these pipes?
  
• How do different drivers work and measure?
  
• Optimal mouth area?
  

I will post my findings when I have time to build the pipes but I do not know when that will be.

Thomas H. Eberhard

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