Bass Extender

[audioguru2]

Are you thinking about getting a subwoofer and amplifier for it to add more deep bass to your sound system?
Years ago I wasn't satisfied with the "ordinary" bass output from my sound system at home that uses pretty good manufactured speakers with 8" woofers and some speakers that I made myself with 8" woofers.
So I designed a circuit that boosts the very low frequency bass frequencies by using a 2nd order Sallen-Key highpass filter with its Q set too high and it made my speakers sound like I have a powerful subwoofer. Of course my amplifier has enough extra power to provide the boost of about 10 times the normal bass power.

I've been using my circuit for nearly 20 years and was going to draw it up and post it here as a project, but recently Silicon Chip magazine published exactly the same circuit in their project. They even use the same TL074 low noise opamp I use.

Go to www.google.com and in the search bar enter Silicon Chip Bass Extender. The 1st link is to their entire article. ;D

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[ante1]

Go to www.google.com and in the search bar enter Silicon Chip Bass Extender. The 1st link is to their entire article. ;DView attachment 37994

 

[audioguru2]

Google looking at Silicon Chip projects work OK for me every time. They must like my cookies or something.

View attachment 37995

 

[ante1]

Hi Audioguru,

I think you’ve got a dishonest computer! ;D

I tried cleaning out the cookie folder but it did not help. 

 

[audioguru2]

Hi Ante,
I have Microsoft IE6 browser.
If I go directly to Silicon Chip Online to look at a project, I get only the 1st page then a begging-for-payment page like you get.
But if I enter the project's name in Google, then the 1st link is to the entire article. Many other people get complete SC projects from Google too. Your pc is too honest or your cookies taste lousy. ;D

 

[Decade]

Hi audioguru!

Do you have any pictures of your sound system?
Would be nice to see.

 

[audioguru2]

Hi audioguru!

Do you have any pictures of your sound system?
Would be nice to see.

Nope. There isn't much to see. Two Acoustic Research speakers about 40 years old (two-way, 8" woofers, sealed cabinets) and some ported two-way speakers I made that have 8" woofers. I have an 18 years old Yamaha stereo receiver with "Low Impedance Drive Capability"  that produces about 70 real Watts per channel into 8 ohms and about 130W per channel into 4 ohms with extremely low distortion. Hidden behind it is my Bass Extender with its 10dB peaks at 30Hz. My sound system sounds like it has a subwoofer.

A couple of years ago, the flexy wires to the woofer of one of my Acoustic Research speakers wore-out because at its resonant frequency of 60Hz its cone makes very long strokes in the sealed cabinet. Recently, the speaker I made that is in the sun most of each day had its woofer's foam surround disintegrate. I am in the process of picking away the glue to the broken flexy wires and replacing them with the wires from the disintegrated speaker.

I have speakers all over my place. Even my cheap little clock radio sounds great and weighs about 5 times more than when it was made. None of my many mods to it stick out of it. ;D

 

[ante1]

I am sure you have a Quad tube amp too! 

 

[audioguru2]

Hi Ante,
I got rid of my only tube amp long ago when I couldn't keep its outputs matched. It was a kit and had horrible distortion.

Today I finished fixing my speaker and it sounds just like new! 5-minutes epoxy cement is wonderful stuff. ;D

 

[ante1]

Hi Audioguru,

I don’t think my hearing could identify the distortion in a “modern” tube amp like this one:

K4040.pdf

 

[audioguru2]

Hi Ante,
That's a nice looking new old amp. Its chrome plating must add something good to its sound.
It has excellent output transformers in a Williamson arrangement, isn't it?
I like the negative feedback around the entire power amplifier part.

415VDC!
Low distortion at only 1W output?
Individual bias adjustments with an LM3914 indicator but not automatic?

 

[Decade]

Hi audioguru!

Why didn't you use Individual bias adjustments in your tube amp?
Tried that in one of my guitar amps with a pair of 6L6, had to do that cause I was in a hurry and those I had were not "perfectly" matched, anyway couldn't hear any difference in sound, usually they are matched both static and dynamically at least they say so  ;D
What is you your opinion about Individual bias adjustments instead of using matched tubes?

 

[audioguru2]

Hi Decade,
I haven't used tubes for about 40 years.
It is probably best to have the best of both worlds. If they are matched then you can hope they wear the same, but if they don't then you can adjust the bias to gain more life from them but at reduced power. ;D

Today my solid-state stereo amp overheated and sounded bad. I played it loud at 260W (real watts) for a couple of hours but forgot to open the glass door on the cupboard that it is in. Boy it got hot!
Guess what? It healed itself after cooling for an hour. ;D

 

[ante1]

260W  for a couple of hours Wow, you must share your taste in music with your neighbors! ;D

 

[audioguru2]

Hi Ante,
My wifey is away visiting relatives this week.
My dog is hiding from the loud but very clean sound and vibrations.
I just installed the Livewire file-sharing program and are downloading all kinds of music.
I am mounting a fan in my amplifier's cupboard.
I'm not deaf yet! I think it is distortion that ruins your hearing.

My neigbours didn't mind, they were blasting awful country music with terrible distortion. ;D

 

[ante1]

So, it’s the “Home Alone”/ grass widower scenario then?

BTW, there is nothing wrong with “Horse Jazz” you know!

Take Care!

 

[Alun]

I just installed the Livewire file-sharing program and are downloading all kinds of music.

Be careful not to download too much pirate music you don't want to be fined now do you.

 

[audioguru2]

Be careful not to download too much pirate music you don't want to be fined now do you.

This is Canada. The government was going to close them down next week, except there is going to be an election soon so they will never get around to it. ;D

 

[Alun]

You can still access Chinese and Latin American sites and be prosecuted for doing so.