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Topic: Analog adjustable bass booster circuit (Read 10755 times) previous topic - next topic
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Analog adjustable bass booster circuit

Hello. I want an analog adjustable bass booster circuit, but it should not boost a range of frequencies at the same amount. It should give more boost to lower frequencies, and most to the lowest frequencies. For example, when it boosts 100Hz by 3dB, it should boost 50Hz by 6dB or something like this, and 35Hz by 9dB or something like this. The potentiometer should adjust the wet-dry value, and I don't need anything below ~25Hz. It should not boost anything above 150-200Hz, and I want to be sure that I don't overdrive the inputs of the amplifier. I want to be able to reduce the boost to almost bypass and I want a fairly wide range to adjust. How can I find or design a such circuit? (I have no problems with soldering.)

Re: Analog adjustable bass booster circuit

Reply #2 –
Quote
For example, when it boosts 100Hz by 3dB, it should boost 50Hz by 6dB or something like this, and 35Hz by 9dB or something like this. The potentiometer should adjust the wet-dry value,

That's pretty-standard for bass & treble control circuits.   A shelf filter is more unusual.



Re: Analog adjustable bass booster circuit

Reply #3 –
Quote from: Klymins on
Hello. I want an analog adjustable bass booster circuit, but it should not boost a range of frequencies at the same amount. It should give more boost to lower frequencies, and most to the lowest frequencies. For example, when it boosts 100Hz by 3dB, it should boost 50Hz by 6dB or something like this, and 35Hz by 9dB or something like this. The potentiometer should adjust the wet-dry value, and I don't need anything below ~25Hz. It should not boost anything above 150-200Hz, and I want to be sure that I don't overdrive the inputs of the amplifier. I want to be able to reduce the boost to almost bypass and I want a fairly wide range to adjust. How can I find or design a such circuit? (I have no problems with soldering.)
If you really want I can give you a bespoke design, but the easy way is to just source a cheap pre-amp board with active tone control.   The bass knob will do almost exactly what you want.
It's your privilege to disagree, but that doesn't make you right and me wrong.

Re: Analog adjustable bass booster circuit

Reply #4 –
Quote from: fooball on
Quote from: Klymins on
Hello. I want an analog adjustable bass booster circuit, but it should not boost a range of frequencies at the same amount. It should give more boost to lower frequencies, and most to the lowest frequencies. For example, when it boosts 100Hz by 3dB, it should boost 50Hz by 6dB or something like this, and 35Hz by 9dB or something like this. The potentiometer should adjust the wet-dry value, and I don't need anything below ~25Hz. It should not boost anything above 150-200Hz, and I want to be sure that I don't overdrive the inputs of the amplifier. I want to be able to reduce the boost to almost bypass and I want a fairly wide range to adjust. How can I find or design a such circuit? (I have no problems with soldering.)
If you really want I can give you a bespoke design, but the easy way is to just source a cheap pre-amp board with active tone control.   The bass knob will do almost exactly what you want.

The built-in bass control of my amplifier is not working like this.

Re: Analog adjustable bass booster circuit

Reply #5 –
Quote from: Klymins on
The built-in bass control of my amplifier is not working like this.
In what way?  OK, so the control both boosts and cuts according to setting (you say you only want adjustable boost), but is there anything else wrong with it?  Perhaps the upper frequency?  If that's the case, it would still be easier and cheaper to go for an off-the-shelf graphic or parametric equaliser than a self-build.
It's your privilege to disagree, but that doesn't make you right and me wrong.

Re: Analog adjustable bass booster circuit

Reply #6 –
Aren't the typical old-fashioned tone controls based on first-order 6 dB / octave (adjusting the cut-off frequency)?
The OP asks for a 3 dB boost between 35 and 50, which is as good as half an octave and just about fine - but then a 3 dB boost for the 50 to 100 octave, that requires more filtering: What then about a first-order boost below 60 and then a shelf to 85 and a first-order between 85 and 100? It's gonna be 1.5 dB off at two frequencies yes - more taps could get it arbitrarily close to desired.

If a parametric EQ has two or more bands that can be set sufficiently low, then it should be easy to fine-tune the outcome to ear, shouldn't it?
(That said, I don't know whether the potentially relevant parametric EQs nowadays work in the "analog" domain, or whether they internally have ADC -> DSP -> DAC circuits. Whether the OP "needs" it to be untainted by zeroes and ones ... their restrictions.)

Re: Analog adjustable bass booster circuit

Reply #7 –
I assumed the OP wouldn't be too tight with his specs!
It's your privilege to disagree, but that doesn't make you right and me wrong.

Re: Analog adjustable bass booster circuit

Reply #8 –
Quote from: fooball on
I assumed the OP wouldn't be too tight with his specs!

Yes, I gave this example just to clarify, I'm not very tight with my specs. I just want a higher slope on lower frequencies. But, I feel like the built-in bass control of my amplifier is using something like a shelf filter, and interestingly I can get a flat-feeling frequency response only when I turn both of the built-in bass and treble controls of my amplifier to their maximum. I get very little bass and treble when I disable the tone controls, and this is definetely because of the amplifier.

Re: Analog adjustable bass booster circuit

Reply #9 –
Quote from: Klymins on
I get very little bass and treble when I disable the tone controls, and this is definetely because of the amplifier.
Wrong frequency response - especially in the bass - is more likely to be due to room and loudspeakers.
Is the amp big enough? Bass could be costly in power terms, and if it is already running short, then a tone control might deplete it further.

Re: Analog adjustable bass booster circuit

Reply #10 –
Quote from: Porcus on
Quote from: Klymins on
I get very little bass and treble when I disable the tone controls, and this is definetely because of the amplifier.
Wrong frequency response - especially in the bass - is more likely to be due to room and loudspeakers.
Is the amp big enough? Bass could be costly in power terms, and if it is already running short, then a tone control might deplete it further.

I'm sure that it is because of the amplifier. The amp is 2x20w and I don't use even a quarter of it.

Re: Analog adjustable bass booster circuit

Reply #11 –
Quote from: Klymins on
I get very little bass and treble when I disable the tone controls, and this is definetely because of the amplifier.
This doesn't seem likely.  Amplifiers, unless they are designed incredibly badly, will have a pretty much flat response across the audio spectrum.  It is far more likely that the speakers (including the cross-over) are the problem.
It's your privilege to disagree, but that doesn't make you right and me wrong.

Re: Analog adjustable bass booster circuit

Reply #12 –
Quote
I'm sure that it is because of the amplifier.
Then replace it!  ;)

Flat frequency response over the audio range (in electronics) has been easy since since solid state electronics replaced tubes in the 1960s.

Re: Analog adjustable bass booster circuit

Reply #13 –
Quote from: fooball on
Quote from: Klymins on
I get very little bass and treble when I disable the tone controls, and this is definetely because of the amplifier.
This doesn't seem likely.  Amplifiers, unless they are designed incredibly badly, will have a pretty much flat response across the audio spectrum.  It is far more likely that the speakers (including the cross-over) are the problem.

I've tried to connect this amplifier to different speakers and different audio sources and the result is interestingly same.

Quote from: DVDdoug on
Quote
I'm sure that it is because of the amplifier.
Then replace it!  ;)

Flat frequency response over the audio range (in electronics) has been easy since since solid state electronics replaced tubes in the 1960s.

This amplifier is already electronic, and it is Lepai LP2020A+.

Re: Analog adjustable bass booster circuit

Reply #14 –
Quote from: Klymins on
Lepai LP2020A+.
Not that a $25 amp is bound to sound horrible - but if you are sure it is a problem, then there might be some cheaper solution than a parametric EQ ...

Also, when you power an amp by a small 12V adapter ... sure that one delivers the juice?

Re: Analog adjustable bass booster circuit

Reply #15 –
Quote
This amplifier is already electronic,
Of course!   What else would it be?  

I'm just trying to reinforce that the electronics are unlikely to be the source of the problem.    Of course it's possible that it is broken.

Quote
I've tried to connect this amplifier to different speakers and different audio sources and the result is interestingly same
Do the speakers sound OK with another amplifier?   If the amplifier is broken or defective, EQ or tone controls are not the way to fix it!

...A broken ground (which could be inside the amplifier or in the cable on the input) can sometimes cause a "center channel vocal remover" effect.   The left & right signals get subtracted so the main vocals (which are usually in the "center"...  identical in both channels) and the bass which is also usually "centered" get eliminated or reduced.   An easy way to test that is to unplug the left or right input connection.    If the bass improves and sound still comes-out of both speakers with only one input connected, that's the problem.

As others have said, "weak bass" is usually the speakers (or headphones).  Or it could be the recording.   Speakers are the weak link when it comes to frequency response.    Almost all speakers roll-off the bass to some extent, and the frequency response varies across the rest of the frequency range too. 

If you want realistic bass that you can feel in your body, you need "big woofers" (or big subwoofers) and "big amplifier".

Re: Analog adjustable bass booster circuit

Reply #16 –
Quote from: DVDdoug on
...A broken ground (which could be inside the amplifier or in the cable on the input) can sometimes cause a "center channel vocal remover" effect.
That's a great point.  Anything which makes the output effectively mono can sound awful (depending on content), but you're talking about subtraction rather than summation, which will be much worse.

There is the possibility of faulty capacitors, although a single dry capacitor might lose the bass or treble on one channel or the other, not both bass and treble on both channels.

Nonetheless, the speakers are squarely in the frame here.  What are they – cheap bookshelf speakers?
It's your privilege to disagree, but that doesn't make you right and me wrong.

Re: Analog adjustable bass booster circuit

Reply #17 –
I tried one of those cheap Lepai digital amps years ago just out of curiosity and quickly binned it as the output was awful.

Re: Analog adjustable bass booster circuit

Reply #18 –
Quote from: Porcus on
Quote from: Klymins on
Lepai LP2020A+.
Not that a $25 amp is bound to sound horrible - but if you are sure it is a problem, then there might be some cheaper solution than a parametric EQ ...

Also, when you power an amp by a small 12V adapter ... sure that one delivers the juice?

Yes, it delivers the juice because I use a very tiny portion of the power capacity of the amplifier. Edit: I'm unable to see the adapter because it is behind some devices but I've succesfully photographed it and it is 12v 5A, so much more powerful than I need. Even 12v 1A would be pretty enough for me.

Quote from: DVDdoug on
Quote
This amplifier is already electronic,
Of course!   What else would it be?  

I'm just trying to reinforce that the electronics are unlikely to be the source of the problem.    Of course it's possible that it is broken.

Quote
I've tried to connect this amplifier to different speakers and different audio sources and the result is interestingly same
Do the speakers sound OK with another amplifier?   If the amplifier is broken or defective, EQ or tone controls are not the way to fix it!

...A broken ground (which could be inside the amplifier or in the cable on the input) can sometimes cause a "center channel vocal remover" effect.   The left & right signals get subtracted so the main vocals (which are usually in the "center"...  identical in both channels) and the bass which is also usually "centered" get eliminated or reduced.   An easy way to test that is to unplug the left or right input connection.    If the bass improves and sound still comes-out of both speakers with only one input connected, that's the problem.

As others have said, "weak bass" is usually the speakers (or headphones).  Or it could be the recording.   Speakers are the weak link when it comes to frequency response.    Almost all speakers roll-off the bass to some extent, and the frequency response varies across the rest of the frequency range too. 

If you want realistic bass that you can feel in your body, you need "big woofers" (or big subwoofers) and "big amplifier".

Yes, they sound much stronger with another amplifier. But it definetely does not because of a broken ground, because I can hear mono files.

Quote from: fooball on
Quote from: DVDdoug on
...A broken ground (which could be inside the amplifier or in the cable on the input) can sometimes cause a "center channel vocal remover" effect.
That's a great point.  Anything which makes the output effectively mono can sound awful (depending on content), but you're talking about subtraction rather than summation, which will be much worse.

There is the possibility of faulty capacitors, although a single dry capacitor might lose the bass or treble on one channel or the other, not both bass and treble on both channels.

Nonetheless, the speakers are squarely in the frame here.  What are they – cheap bookshelf speakers?

They are DIY-boxed sealed-box 30w three-way drivers.

Quote from: john33 on
I tried one of those cheap Lepai digital amps years ago just out of curiosity and quickly binned it as the output was awful.

I get a very good audio quality with this amplifier when I turn bass and treble up.

Re: Analog adjustable bass booster circuit

Reply #19 –
Quote from: Klymins on
Quote from: Porcus on
Quote from: Klymins on
Lepai LP2020A+.
Not that a $25 amp is bound to sound horrible - but if you are sure it is a problem, then there might be some cheaper solution than a parametric EQ ...

Also, when you power an amp by a small 12V adapter ... sure that one delivers the juice?

Yes, it delivers the juice because I use a very tiny portion of the power capacity of the amplifier.

If you want help, read the question before gobbling up answers like that. You are already working hard to convince fellow users that you are a troll account, and even if you aren't: You are wasting people's time, and when you have done enough of that - do you expect them to try to help?

Re: Analog adjustable bass booster circuit

Reply #20 –
Quote from: Klymins on
Yes, it delivers the juice because I use a very tiny portion of the power capacity of the amplifier. Edit: I'm unable to see the adapter because it is behind some devices but I've succesfully photographed it and it is 12v 5A, so much more powerful than I need. Even 12v 1A would be pretty enough for me.
That's a pretty poor appreciation of the actuality.  It's no good assuming an average of 12W means the amp only needs 1A @ 12V.  The instantaneous peak requirement will be much, much higher than that.

So you're saying this amplifier uses an external mains to DC adapter?  That sounds crap for a start.  You need the minimum possible distance between the DC rail smoothing capacitors and the output transistors, and the minimum possible inductance in the conductors.

Quote
They are DIY-boxed sealed-box 30w three-way drivers.
Using what drivers, specifically?

Quote
I get a very good audio quality with this amplifier when I turn bass and treble up.
So turn the bass and treble up and be done with it.
It's your privilege to disagree, but that doesn't make you right and me wrong.

Re: Analog adjustable bass booster circuit

Reply #21 –
Quote from: fooball on
Quote
I get a very good audio quality with this amplifier when I turn bass and treble up.
So turn the bass and treble up and be done with it.

I already do this. I just want something more than a flat frequency response, but this configuration is okay for me.