Midrange attenuation of 4-5dB needed

[chuck55]

My single driver speaker has a 4-5 dB boost centered around 1kHz. I would like a tone control to provide a gradual dip centered at the 1kHz to offset the "frowny face" FR that I now have.

Perhaps just use the midrange tone control on this design?
TC3 Three Band Tone Control Equalizer DIY Kit Bass Mid Range Treble Stereo | eBay

I do not need a volume pot as I do not need variable, just a fixed 4-5dB, attenuation.

Could someone here suggest something with better sound quality? Could someone here build this midrange tone control for a fee?

 

[ChristianThomas]

Do you have a frequency response for the speakers as they are? Would that not be the place to start?

 

[chuck55]

Hi Christian, did you read my post? The answer to your question is there.
Can you help with a midrange tone control?

Thanks

 

[ChristianThomas]

Yes, I did read it. I just didn't believe it was a full description.

You can have different slopes towards a centre frequency (which will decide on what order of filter you need), different flatness at the top, and peaks are very rarely symmetrical. Also, it is in the nature of minimum phase things (including speakers) for a peak to be almost invariably accompanied by a corresponding dip. The complexity of the problem may therefore go beyond what a basic filter such as the one shown can achieve.

If you think that the tone control here happens to meet your needs, and it does seem to centre on or close to 1kHz, then $68 would be a pretty cheap way of achieving it. It would even be worth it to find out what part of what you need it does do. Sometimes, some of these eBay offerings give some of the cheapest R&D that can be found.

 

[chuck55]

If you think that the tone control here happens to meet your needs,

If you read my original post you would see that no, it does not:

1) I do not need treble and bass boost.
2) I do not need variable attenuation - i.e. pot

You can have different slopes towards a centre frequency (which will decide on what order of filter you need),

The most efficacious range would be 500-1,500 Hz but the F-R varied so much around the room that those exact numbers are not set in stone. The average between the high and low is, as you can see, 1,000Hz.

That's why I posted here. Those on Ebay have pretty distorted sound. So much so, that in many cases I'd rather live with the uneven F-R. If that Ebay tone control met my needs I would not have posted.

Do you have a midrange tone control in mind? One that would minimize phase shifts and all that other stuff that the usual "specs" fail to define? HD, etc. does not say much as to final sound quality IME. I have used Behringer, Parasound, and Denon UDM-31. For some strange reason only the cheap Denon m-s did not audibly distort the sound. So if you know of a design like the Denon, that would be ideal.

Have a great weekend!

 

[cod3gen]

Something like this you are looking for? Expandable Graphic Equaliser

 

[ChristianThomas]

If you read my original post you would see that no, it does not:

1) I do not need treble and bass boost.
2) I do not need variable attenuation - i.e. pot


The most efficacious range would be 500-1,500 Hz but the F-R varied so much around the room that those exact numbers are not set in stone. The average between the high and low is, as you can see, 1,000Hz.

That's why I posted here. Those on Ebay have pretty distorted sound. So much so, that in many cases I'd rather live with the uneven F-R. If that Ebay tone control met my needs I would not have posted.

Do you have a midrange tone control in mind? One that would minimize phase shifts and all that other stuff that the usual "specs" fail to define? HD, etc. does not say much as to final sound quality IME. I have used Behringer, Parasound, and Denon UDM-31. For some strange reason only the cheap Denon m-s did not audibly distort the sound. So if you know of a design like the Denon, that would be ideal.

Have a great weekend!

I can't think why the eBay ones should be distorted. There's not much to them and you could change the op amps anyway.

Did I have a control in mind?

No. I would have designed it from scratch. Unfortunately you appear to be too rude to make that an enjoyable prospect.

Have a great weekend, Chuck.

 

[chuck55]

cod3gen, thanks for the link but I don't know, they write:
" Phase shifts tend to be a little more radical, and the passband has more ripple than a conventional circuit, but only where a number of sliders are set to boost or cut. "

I don't need sliders or individual frequency adjustment.

No. I would have designed it from scratch. Unfortunately you appear to be too rude to make that an enjoyable prospect.

ChristianThomas, people like you are easy to figure out. No surprises there.

1) Ask a bunch of impressive sounding questions.
2) Tease me that you could do something.
3) Then throw out insults at me as an excuse not to.

Enjoy yourself!

 

[jerluwoo]

What your wanting is probably best done at the speaker end of things, but that would be more expensive with the need for inductors. My best recommendation is a simple buffered notch filter. This gives around -6db at 1kHz and -3db at 500Hz and 1.5kHz. I can't make any promises on sound quality and the like so it's up to you.

 

[Zero D]

Hi i was going to suggest a Twin T Notch Filter, but i see jerluwoo has already posted one

I would prefer a 2 OpAmp per channel solution myself though. If your'e interested, just holla

 

[Aniket]

Just make this and connect between your source and amplifier.

 

[Aniket]

Or use a trim pot in place of R10, as shown to vary your mid frequency.

 

[Zero D]

Corretion

@ Aniket

Hi, i havn't simmed etc your circuit, but i did notice the - Voltage Supply needs reversing

Regards

 

[Aniket]

Yup, my mistake, it just denotes +/-15V supply voltage. no more error's in the circuit.

 

[chuck55]

Thanks Aniket. I like the concept.

Is this a 1st order design or will there be phase shift?

 

[Aniket]

there will be no phase shift, as 2nd op amp would correct phase shift of 1st, making the output signal in phase with input signal.

 

[chuck55]

Since the line level tone controls provides so much audible distortion, I thought I would try one after the power amp. Like a regular crossover component. I got this info from Parts Express but they could only design for -9db. From my testing with equalizers, I know -9dB is much too high.
Does anyone here know what value I use to cut the center attenuation down to -4 to -5 dB? Here is what they gave me:

The low -3 dB frequency would be
600 Hz, the center frequency at 900 Hz, and the upper -3 dB
frequency at 1200 Hz. The amount of attenuation at the
center should be about 9 dB.

Capacitor: 33 uF (027-350)
Inductor: .8 mh (255-044)
Resistor: 2.4-ohms (004-2.4)

They are all twisted in parallel and connected to the plus speaker terminal.

 

[sreten]

Hi,

No way will a parallel LCR with 2.4R, in series with the driver give
-9dB. With Re near 3R = -5dB max , with Re near 6R = -3dB max.

rgds, sreten.

 

[chuck55]

Hi,
with Re near 6R = -3dB max.rgds, sreten.

Thanks sreten. So with the capacitor and inductor values unchanged, do you mean switching to a 6 ohm resistor will give -3dB at the center?
What will the reduction be at the low 600hz and the high 1,200 hz?

 

[chuck55]

I am confused. The circuits design by both jerluwoo and Aniket have two op-amps in them. Both circuits have a single input and a single output. So how is Aniket's a two opAmp design but jerluwoo is not?