[Elecraft] Meaning of EQ bands?

[Joe Subich, W4TV]

> The existing K3 manual seems quite misleading in talking about 8
> "bands" of audio equalization. We now learn that the EQ facility
> allows the user to set the relative levels at 8 discrete frequency
> POINTS, and that the rest of the frequency response is interpolated
> by "joining up the dots".
>
> That gives quite a different shape to the frequency response than
> many will have imagined.

How so?  That's the way "graphic" equalizers - whether they are
octave or fractional octave - have operated for years.

73,

    ... Joe, W4TV



On 6/21/2012 6:51 PM, Ian White GM3SEK wrote:
> Thank you for the clarification, Lyle.  I hadn't seen that information
> anywhere before.
>
> The existing K3 manual seems quite misleading in talking about 8 "bands"
> of audio equalization. We now learn that the EQ facility allows the user
> to set the relative levels at 8 discrete frequency POINTS, and that the
> rest of the frequency response is interpolated by "joining up the dots".
>
> That gives quite a different shape to the frequency response than many
> will have imagined.
>
>
>>> How exactly are the EQ bands implemented in DSP, in terms of frequency
>>> response?
>
>> In the KX3, the gain of the FIR filter at the specified frequency is
>> set to the requested value, and a linear interpolation is performed
>>from the next lower specified frequency.  At the highest frequency,
>> sertting, all frequencies higher are set to the requested value.
>>
>> The K3 operates in a similar fashion.
>>
>> These are inputs to the FIR coefficient generator along with
>> center/width/lo cut/hi cut and manual notch to create the FIR filter.
>>
>> 73,
>>
>> Lyle KK7P
>>
>