Resource to calculate, building and measuring Hi Fi Loudspeakers and more...

Sunday, 20 January 2019
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  My System

"The sole objective of the audio industry as a whole is to sell products..."

Projects which are planned, in progress or finished   Free distortion and performance analysis software that i'm using for my measurements

 Active Components

 Passive Components

Tube Line Pre-Amplifier I Tube Line Pre-Amplifier II Tube Buffer-Amplifier Tube Phono Pre-Amp   MM-Phono Pre-Amp Accuphase Dynavox VR 70-E Passive Pre-Amplifier Transformer Attenuator Passive Mains Filter



Rega P2 RB300 Tonearm Denon DL 160 Metz DE81 Cartridge Specs. Tonearm/Cartridge Capability StepUp Transformers TML Basspipe   in-akustik Reference LS-602 Loudspeaker Cable   Bowers & Wilkins CDM 1   Syntar 200 T Jordan Horn Speaker Interconnect M550i 4PR Loudspeaker Cable PC Satellite Loudspeaker


2 meters TML Bass Pipe


Finished Pipe


Nearfield measurement with second order lowpass filter ( 10mH and 120uF )

  The idea is simple:
remember an organ... Pipes, a lot of pipes. Small sized and sometimes very big ones.
So, i took a PVC tube with 8 inches diameter and 2 meters log, mounted a 8 inch woofer and tried to get some bass.

TSP of used woofer:
fs: 32Hz
Qts: 0.33
Vas: 98 liters
SPL: 92dB

To calculate the resonant-frequency of this 2 meter tube:
fs = c / ( 4 * l )
c = 344 meters ( speed of sound )
l = length of tube in meters and 4 because is a quater-wave-pipe

Resonant frequency of the pipe = 344 / ( 4* 2 ) = 43 Hz


Woofer Base

Woofer impedance


Impedance ( no filter and no filling )

Impedance ( with filter and filling )


Second OrdProjects/er ( 12dB ) crossover

Bowers & Wilkins Compact Domestic Monitor 1

I was long searching for B & W Loudspeakers. Now I've found what I was looking for: B & W CDM 1.


Voted "Loudspeaker of the Year" by European journalists in 1995.

B&W is an example of a company that got very big by doing things right, and still does.
They manufacture their own drivers. Quality control is tops.

The CDM 1 exudes quality. Cabinetry is first-rate. The black ash finish looks stunning in my living room. The CDM 1 is a two-way design rated at 88dB/2.83V/m sensitivity.
Nominal impedance is rated at 8 ohms, going down to a minimum of 4.5 ohms.

Electrical impedance (solid) and phase (dashed) (2 ohms/vertical div.)

Notice the bullet-shaped nose cone smack in the middle of the woofer's voice-coil, in lieu of a dustcap. B&W calls it a "dispersion modifier." There's only so much bass you can get from a small speaker, but the CDM 1 does very well, except for the lowest octave.
Better banish that lowest octave than have the deep bass shake the cabinet and muddy the sound! You could always mate the CDM 1 with a good subwoofer.

The bass performance is very much dependent on the amplifier.

Anechoic response on tweeter axis at 50", averaged across 30 degrees horizontal window and corrected for microphone response, with complex sum of nearfield woofer and port responses plotted below 300Hz

Step response on tweeter axis at 50" (5ms time window, 30kHz bandwidth)

The enclosure is constructed from 3/4" MDF, and is made rigid by a vertical brace at the sidewall centers. I want to call this a "figure-8" brace, except that it has three rather than two holes. The cabinet walls are lined with 1" foam. The reflex port, almost 2" in diameter and 6" deep, is situated on the front baffle immediately beneath the woofer and is flared to minimize wind noise.

The High Frequency unit is a metal-dome unit descended from the 1" tweeter used in B&W's classic Matrix 801 design. The 6.5" woofer features a yellow cone formed from Kevlar, the synthetic material used in bulletproof vests. The woofer cone is also surrounded by a circular plastic molding to minimize reflections. The tweeter is covered with a black wire mesh, the woofer and port with an elliptical grille made from black cloth stretched over a minimal plastic space frame.

The crossover is set at 3kHz, with the circuit mounted on a small printed circuit board attached to the inside of the inset plastic terminal panel. The woofer low-pass filter appears to consist of a single soft-iron-cored series inductor, while the tweeter high-pass filter, a damped T section, features an air-cored inductor and non-polar electrolytic capacitors.

two-way, reflex-loaded, stand-mounted loudspeaker
Drive-units: 0.75" (18mm) metal-dome tweeter, 6.5" (165mm) Kevlar-cone woofer
Crossover frequency: 3kHz
Frequency response: 64Hz-20kHz ±2dB
Sensitivity: 88dB/W/m (2.83V)
Nominal impedance: 8 ohms
Amplifier requirements: 30W minimum

Dimensions: 15" (381mm) H by 9" (229mm) W by 11" (280mm) D.
Weight: 18 lbs each.

Modifications Crossover

I discovered that standard low-cost components were used in the cross-over.
The problem is on the capacitor. These are expected to age significantly. An increasing fatigue in the heights I could definitely identify with the years.

Original crossover of CDM 1

Tuned Highpass (Audyn caps)

Tuned High & Lowpass


This is a collection of music professionals talking about the new B&W 800 Series.

Nexus i Speaker Stand

  The complete stand is manufactured from heavy gauge steel and the assembly is made using upgraded high tensile fixings to maintain optimum rigidity.

For improved performance, the centre column is designed to be mass loaded with the optional Atabites while Isolation Gel pads are now included as standard.

The top plate is manufactured from 4mm thick steel plate and carpet spikes are included.

Visit Atacama

Syntar 200 T
I like the Chario Syntar 200 Tower and this speaker is not expensive!

3-way Floorstander


Sensitivity:              90 dB SPL 2.83V/1m
Frequency @ -3dB:   55 Hz
Acoustic Allignment:  LR4-Like *
Rated Impedance:     4 Ohm
Configuration:           3 way vertical array
Size:                       960x210x300
Weight:                   20kg

* Fourth order Linkwitz-Riley crossovers (LR4) are probably today's most standard type of audio crossover. They are constructed by cascading two second order Butterworth filters. Their steepness is 24dB/octave (80 dB/decade).

Link to Chario

Jordan Horn
This Horn Speaker is build in 2001 (just for fun and my EL84 Amp)

E.J. Jordan horn with only one transducer the entire audible frequency range to show, is the probably most fastidious goal of a loudspeaker chassis developer. The broadband loudspeaker chassis JX92 of Ted Jordan supplies a smooth frequency response with its light and rigid aluminum diaphragm up to 20kHz.

As housing for this transducer a bass horn is the best solution. A horn loudspeaker is with correct adjustment to the driver easily in a the position to improve the efficiency around the factor 10 which corresponds to a level gain of 10 decibels.

The loudspeaker must be aligned both horizontal and vertically for hearing position, since the JX92 bundles the sound clearly starting from 4kHz. In addition the housing at the front edge can be placed on spikes.
The position in the area is uncritical: During hitting a corner list the bass becomes more pressureful, in addition, before a wall or freely set up bass is present in sufficient quantity.

Very pressureful and precise the bass of the E.J. Jordan horn sounds, whereby extreme low bass is missing.
From the middle bass situation upward into the basic clay/tone range the loudspeaker supplies with to very much pressure, to be dosed by the damping of the horn.

Jordan Horn

Sensitivity:              89 dB SPL 2.83V/1m
Frequency @ -3dB:   45 Hz
Rated Impedance:    8 Ohm
Size:                       85cm x 24cm x 50cm
Weight:                   28kg

At this time i used a Tubeamp (based on the EL84) with only 6 Watt per chanel.

The used driver is the famous Jordan JX92

  • a tweeter will be added ( 4kHz - 20kHz )
  • new impedance & frequency measurements
  • the crossover network has to be designed
  • the notchfilter (150Hz problem) will be recalculated

  • listening tests

All measurements and new pictures coming soon ( 2-3 weeks )

To follow this project take a look here

Download that E.J. Jordan Horn (full-size)

More E.J. Jordan Loudspeaker Plans   PDF (236KB)

inakustik LS-602

For 5 years Kimber 4PR...
Time for something better

The Reference LS-602 is a double-symmetrical cable design.
The high density reduces the inductance factor to the beneit of the medium and high-frequency ranges.

  • Quatro CC-187 design; 4 x 1.87 mm2
  • Double-symmetrical design
  • 37 wires concentrically stranded per conductor
  • DUO-PE II insulation around each conductor
  • PE network jacket reduces micro-vibrations and capacitance
  • Low induction for homogeneous reproduction

Link to: in-akustik

Monster Cable
M550i™ audio interconnect has multiple-gauge wire networks for more natural music reproduction.

Link to: Monster-Cable

M 550i

Kimber Cable
For years and years I was using standart speakercable...
Now I bought something good (for a good price) ;-))

Four brown and four black braided conductors
2 x 14awg / 2.08mm2
High-purity copper
Special formula polyethylene dielectric.

The performance of 4PR is evident on even the most modest systems. With 4PR, bass and treble frequencies are allowed their full extension, while dynamics emerge unrestrained. Through the use of our proven braided technique, 4PR rejects noise regardless of length, making it an excellent cable for professional, studio and home use.

Link to: KimberCable


PC Loudspeaker

Satellite Loudspeakers for Personal Computer

for my son Rik

System:Sealed Enclosure
Alignment / Qt:0.66 ( better impulse respons )
f-3dB:130 Hz
Network:Highpass 6 dB @ 4000 Hz
Bass/Midrange: NA 130 ( out-of-production )
fs: 64.32 Hz
Re: 5.9 ohms [dc]
Qes: 0.34
Qms: 2.18
Qts: 0.30
Mms: 5.59 grams
Rms: 1.03 kg/s
Cms: 0.001095 m/N
Bl: 6.23 Tm
ETA: 0.71%
Sd: 78.45 cm2
Vas: 9.7 ltr
SPL: 91.92 dB @ 2.83V/1m
Tweeter: SC 10 N ( Visaton )
fs: 1700 Hz
Re: 6.9 ohms [dc]
Mms: 0.1 grams
Bl: 1.3 Tm
Sd: 5 cm2
SPL: 90.1 dB @ 2.83V / 1m

recommended cutoff frequency: 4 kHz/12 dB

Because a Subwoofer is used, f-3dB @ 130 Hz is perfect...

MDF 18mm
4 pieces180 x 320mm
4 pieces156 x 320mm
4 pieces120 x 180mm

Inside measurements:
12cm x 18cm x 24cm=5.18ltr
Vb = (5.18ltr - DrviverVol = 0.3ltr)=4.88 ltr

New Network: 12dB Crossoverfrequency (acoustical: 2.5kHz, electrical: 1.7kHz)

The network is totaly recalculated. One capacitor is not working...

Now it's a 12db network with impedance compensation for Midwoofer and Tweeter. There are problems at 6.5 kHz and 10kHz.
This is caused by the Tweeter...
But i don't change this because the network components would be 4 times the money as the both drivers...

And, the speaker is used as PC loudspeaker and not as HiFi loudspeaker.

Calculated and optimized Frequency-Response

The final PC monitor-loudspeaker