Project: My loudspeaker Sys. & Networks thereof

Thread Starter

PeteHL

Joined Dec 17, 2014
298
Since this is a forum about circuits, I'll start with a description of the crossover and baffle step compensation circuits of my speaker.

Crossover Network

The schematic diagram of the crossover network is at Fig. 16 on page 24 of my article attached as a PDF document.

The network is very conventional with second order Linkwitz-Riley high-pass and low-pass filters. The inductors of the network were wound on 2.5 inch diameter cylinders from 3/4 inch MDF with masonite (aka hardboard) sides nailed and glued to the MDF core. It takes about 90 Feet of 18 AWG enameled wire wound around the core to get the required inductance. Towards the end of hand-feeding wire to the form rotated by a motor, the winding inevitably becomes scramble-wound, but it still works to get the inductance needed.

The network includes a Zobel or impedance equalizer, resistor R1 and capacitors C3 and C4 in the schematic.

There is a photo attached to this thread of one of the constructed networks in the bottom of a speaker-tower, partly attached to the bottom panel of the closed-box for the woofer of the system.

Here is a listing of components:

R1 6R2- Ohm 25W cement resistor
C2 = C1- 2u6 100V 5% metallized polyester film
C3=C4- 6u8 160VAC 5% metallized polypropylene
L2=L1- 1.3mH
3 of 8 lug terminal strips
1 of 6 lug terminal strip

Baffle Step compensation (BSC) network

This is placed in the tape monitor loop of my receiver dating from the previous century. That is, it takes the stereo signals at line level from the pre-amplifier and outputs to the power amplifier for driving the speakers.

The schematic diagram of the BSC network is at Fig. 16 on page 25 of the attached article. There is also a photo of the BSC Network attached to this thread.

Components of the circuit ( one for each of the two stereo channels) are:

R3=R2- 2k7 1/4W 5% carbon film
C5- 0u12 (in my case 0u02 polyester film 5% // 0u1 metallized polyester 5%)
1 inch by 2.25 inch section of strip board

After soldering the components and connecting cables to the strip board, the section of strip board was hot-glued to one-half of the tiny clam shell box.

There is a photo of my pair of speakers attached to give you an idea of what my design of a two-way loudspeaker system involves.

In my article I very thoroughly explain what my design intends to accomplish, how it is accomplished, and it includes the results of on-axis frequency response testing. Some of my design is original, but it mainly draws on some of the work of Linkwitz, Barron, Geddes and Rindel.

RWTW-XOVER.JPG RWTW-BSCNET.JPG RWTW-SPKR.jpg
 

Attachments

Last edited:

Saluki

Joined Feb 23, 2019
3
Interesting project. There have to be some significant diffraction issues, though. That said, in my experience fewer people are bothered by such, if modest, than are.
 

Thread Starter

PeteHL

Joined Dec 17, 2014
298
Interesting project. There have to be some significant diffraction issues, though. That said, in my experience fewer people are bothered by such, if modest, than are.
Thank you. There are design features that are meant to minimize diffraction. For one, Fig. 7 shows that none of the reflections off of the integrated (plaster of Paris) reflector are obstructed by the tweeter's baffle. Then also in Photo 1, the tweeter and reflector mounting results in the tweeter halfway in front of the front panel of the tower and a portion of the reflector is also in front of the tower's front panel.
 
Top