The Bass Effect

[audioguru]

Years ago, there was a speaker project in a magazine called "The Sweet Sixteen".
It used 16 cheap little speakers that were all different so their resonances occurred at different frequencies.
It produced no bass even though the total cone area was huge.
It was very directional and very loud.

 

[4pyros]

Wow audioguru that gose way back. I think the 1st hard of "The Sweet Sixteen" was from my Grandfather. I think it came out in popular science. It may be to BIG for a desk top box, but it vary interesting. The theory is coming back as of lately mainly with subs. Its funny how some things go full circle.

Multiple Small Subs - Geddes Approach - diyAudio

Andy

 

[audioguru]

The Sweet Sixteen speaker system was a bad idea because it used cheap little speakers that produced no bass sounds. The author was wrong to believe that a large cone area produces good bass frequencies when each cheap little speaker produced no bass frequencies.

I am still using the second speaker I ever made that is about 45 years old. It uses a 5" Philips woofer and a Philips 1" dome tweeter in a sealed enclosure. It still sounds pretty good.

 

[learning]

Today I made a new speaker enclosure(height-14"/Wide- 6"/Depth-9") with a 3" Tweeter (4Ohms/40 Watts) and 6" Woofer(4 Ohms/40 Watts) as I am getting a little bass effect with a power supply (3Amp Step down Transformer/2 1000uF/35 Volts capacitors/150 ohms-5 watts resistor). How I can a decent bass effect from this configurations ?

 

[audioguru]

To produce good bass, the woofer must have a low resonant frequency and a rubber surround so its cone can move a lot.
Post the datasheet for the woofer so we can see its spec's.
It the enclosure completely sealed? Is the enclosure strong thick wood so it doesn't resonate?

Post the schematic of the crossover network.

Why is there a wasteful resistor in your power supply? 1000uF is too small for good bass with 4 ohm speakers.

Post the schematic of the power supply and amplifier.

 

[learning]

To produce good bass, the woofer must have a low resonant frequency and a rubber surround so its cone can move a lot.
Post the datasheet for the woofer so we can see its spec's.
It the enclosure completely sealed? Is the enclosure strong thick wood so it doesn't resonate?

Post the schematic of the crossover network.

Why is there a wasteful resistor in your power supply? 1000uF is too small for good bass with 4 ohm speakers.

Post the schematic of the power supply and amplifier.

Thank you for your reply !

I am using a local speaker maker's woofer. It does not have any email or website or any communication because this manufacturer never contact with general customer and it only deals with only dealer. But this woofer have no datasheet.

The enclosure is completely sealed. It is made of thick plywood (1 mm).

I am not using any crossover network for this speaker system.

A 4700 uF or 10000 uF capacitor, which one I should use ?

 

[audioguru]

I am using a local speaker maker's woofer. It does not have any email or website or any communication because this manufacturer never contact with general customer and it only deals with only dealer. But this woofer have no datasheet.

A speaker without a datasheet showing its important spec's is cheap garbage. Your world is very different to our world. Most of us use a name-brand woofer that has a detailed datasheet.

The enclosure is completely sealed. It is made of thick plywood (1 mm).

1mm is much too thin. The wood should have a thickness of at least 10mm.

I am not using any crossover network for this speaker system.

Horrible. Then the load on the amplifier is 2 ohms and the tweeter will probably be damaged by bass frequencies. The woofer sounds awful at high frequencies and needs a lowpass filter and the tweeter needs a highpass filter.

A 4700 uF or 10000 uF capacitor, which one I should use ?

For what? A series 13uf non-polar capacitor will make a poor quality highpass filter for the 4 ohm tweeter.

It is easy to measure the resonant frequency of the woofer. Then its response drops at 12dB/octave below its resonant frequency in the enclosure.

 

[learning]

A speaker without a datasheet showing its important spec's is cheap garbage. Your world is very different to our world. Most of us use a name-brand woofer that has a detailed datasheet.


1mm is much too thin. The wood should have a thickness of at least 10mm.


Horrible. Then the load on the amplifier is 2 ohms and the tweeter will probably be damaged by bass frequencies. The woofer sounds awful at high frequencies and needs a lowpass filter and the tweeter needs a highpass filter.


For what? A series 13uf non-polar capacitor will make a poor quality highpass filter for the 4 ohm tweeter.

It is easy to measure the resonant frequency of the woofer. Then its response drops at 12dB/octave below its resonant frequency in the enclosure.

How to make a good quality highpass filter for the 4 ohm tweeter ? I also add a 1000uf cap with 150 ohm resister in series on tweeter terminals.

How to measure the resonant frequency of the woofer ?

 

[audioguru]

How to make a good quality highpass filter for the 4 ohm tweeter?

Most two-way speakers use a series capacitor and an inductor in parallel with the tweeter to produce a second-order highpass filter. They use a series inductor and a capacitor in parallel with the woofer to make a second-order lowpass filter. The result is a notch at the crossover frequency so one of the speakers must be connected inverted. Then the result is a peak of 3dB at the crossover frequency.

I also add a 1000uf cap with 150 ohm resister in series on tweeter terminals.

A 150 ohm resistor in series with a 4 ohm tweeter cuts the level to the tweeter to only 2.6%.
The 1000uF capacitor in series with 154 ohms passes frequencies down to only 1Hz.
You need to learn about how to calculate the cutoff frequency of capacitors and resistors (speakers).

How to measure the resonant frequency of the woofer ?

Connect a 47 ohm resistor in series with the speaker. Connect an audio voltmeter or oscilloscope across the speaker. Connect a sine-wave generator to the input of the amplifier.
At a frequency of about 800Hz, adjust the generator output level so the amplifier is not clipping.
While observing the output of the speaker level, reduce the frequency of the generator until a peak is seen.
The peak is the resonant frequency. For good bass it should be 40Hz or less.
I bet yours is 160Hz or more. Then you will have very little bass effect.

 

[learning]

Thank you for your inputs !

How I can calculate the cutoff frequency of capacitors and resistors ?

 

[blueroomelectronics]

Use a crossover calculator.
2-Way Crossover Designer / Calculator

 

[learning]

Use a crossover calculator.
2-Way Crossover Designer / Calculator

Today I add a crossover network each in both the speaker enclosures and working better than the previous performance. Here it is my crossover network configurations which I have got from the datasheet of it as follows:

Rated Impedence :
Type: 1000/6000 - 4 ohm
Type :1000/6000 - 8 ohm

CrossOver Frequencies:
1000/6000 Hz

Power Handling Capacity :
100w

Stope:
Low Pass: 6 db/Octave
High Pass: 6 db/Octave

 

[audioguru]

You have only a woofer and a tweeter so you need a crossover network for a 2-way speaker. It has only one crossover frequency, usually about 3kHz to 4kHz.
But you made a crossover for a 3-way speaker that has a midrange driver therefore the crossover has two cutoff frequencies: 1kHz between the woofer and the midrange and 6kHz between the midrange and the tweeter.

A typical crossover network is second-order so that the slopes drop at 12dB/octave.
But you made a first-order crossover that has slopes of only 6db/octave that are nearly useless.

Here is one of many articles found in Google about speaker crossover networks: **broken link removed**

Here is a very simple 2-way second order crossover network:

 

[learning]

You have only a woofer and a tweeter so you need a crossover network for a 2-way speaker. It has only one crossover frequency, usually about 3kHz to 4kHz.
But you made a crossover for a 3-way speaker that has a midrange driver therefore the crossover has two cutoff frequencies: 1kHz between the woofer and the midrange and 6kHz between the midrange and the tweeter.

A typical crossover network is second-order so that the slopes drop at 12dB/octave.
But you made a first-order crossover that has slopes of only 6db/octave that are nearly useless.

Here is one of many articles found in Google about speaker crossover networks: **broken link removed**

Here is a very simple 2-way second order crossover network:

Tomorrow I will visit the market for searching crossover network as I think the chance for getting it is very bleak. So I like to build inductor at home as can you tell me how to build it !

 

[learning]

You have only a woofer and a tweeter so you need a crossover network for a 2-way speaker. It has only one crossover frequency, usually about 3kHz to 4kHz.
But you made a crossover for a 3-way speaker that has a midrange driver therefore the crossover has two cutoff frequencies: 1kHz between the woofer and the midrange and 6kHz between the midrange and the tweeter.

A typical crossover network is second-order so that the slopes drop at 12dB/octave.
But you made a first-order crossover that has slopes of only 6db/octave that are nearly useless.

Here is one of many articles found in Google about speaker crossover networks: **broken link removed**

Here is a very simple 2-way second order crossover network:

Here it is the PCB of 2-Way Crossover Network as tell me correctness about it !

Thank you !

 

[blueroomelectronics]

That's one awful autorouter, do it freehand as use as much copper as you can.

 

[audioguru]

Tomorrow I will visit the market for searching crossover network as I think the chance for getting it is very bleak. So I like to build inductor at home as can you tell me how to build it !

Your Indian world is very different to my Canadian world. I can buy anything I want.
You should ask an Indian where to buy a crossover network or where they get wire and the instuctions to make inductors.

 

[learning]

Your Indian world is very different to my Canadian world. I can buy anything I want.
You should ask an Indian where to buy a crossover network or where they get wire and the instuctions to make inductors.

Before go out for the market I already contacted the dealer for the 2-way crossover network but they told me that it will not be available today may be a couple of days later. But 3-way cross over network is available as I will cut down the midrange connection to make it 2-way crossover network. Am I right ? I never give up and I will do it in time. Put your views about my thinking !

 

[learning]

That's one awful autorouter, do it freehand as use as much copper as you can.

Is my PCB correct ?

 

[learning]

Can you tell me the usefulness of this crossover network for my speaker system ?

Thank you !