[Elecraft] W2IHY 8 band equalizer and EQ Plus

[Guy Olinger K2AV]

Hi Lu.

Schematics for the K3 are downloadable PDF on the Elecraft website.
Many questions can be answered right off just digging into the
drawings.  I find the ability in Adobe Reader to search in the PDF
text very useful for finding stuff.  Device specifics are in the
schematic, so I guess you could go looking for a manufacturers
technical writeup and figure out the granularity from that.

I think that some of what you are calling "punching" really is just
the K3 dealing with sudden power spikes.  Professional microphone
technique would not include very soft followed by very loud.  The K3
is interpreting the loudest audio as being the intentional "top" of
your speaking pattern and is setting power management to NOT punch out
the amp and cause ALC spikes coming back from the amp.  This effect
would be further exacerbated if all of the various TX power
calibrations had not been done correctly, as it will be further
exacerbated if the users manual MIC/CMP/PWR setting procedure is not
used.

The terms you are using to describe the K3's internal functioning will
remain speculative unless Wayne publishes stuff, and our thought
patterns still have have that analog, sequential function sound to
them : >)

 K3 has a digital transmit envelope management function that should be
preceded by proper TX gain calibrations, and the user manual
MIC/CMP/PWR setting.

73, Guy.


On Wed, Apr 28, 2010 at 11:03 PM, Luis V. Romero <lromero at ij.net> wrote:
> Some quick questions (yeah, I know I said I would stop, but I cant help it,
> I want to understand!)
>
>>"...a Pre-DSP two band audio leveler/AGC and handles for Attack, Decay and
> Ratio on the RF Clipper."
>>
>>That is, prior to Digital Signal Processing, or before analog is converted
> to digital.
>
> Where exactly does the input to the TX DSP section (OK, IF section) hit an
> ADC?  Where do we move from the Analog domain to the Digital domain?  Where
> is the "quantizer" for the mic input?  Would make sense if it was before the
> Clipper, right?
>
>>In your headroom explanation, is there a common instance of microphone ADC
> saturation that needs to be reported?  >That's a pretty seventh-grade
> mistake on Wayne's part if it's true.  (Yeah, I know, the first Hubble
> lenses, and >the unit snafu on the Mars landers, also very seventh-grade.)
>
> I don't believe that's it at all.  I can punch holes into the audio if I
> speak softly then speak loudly.  Sounds to me like there is some kind of
> compression happening (that is why I first incorrectly assumed that this
> thing used a compressor not a kind of IF/RF Clipper).  What happens is that
> the radio grabs the loud syllable and holds off from releasing the gain
> reduction for a bit, then recovers.  If you hit it with something loud, then
> something soft, you hear the hole.  The decay of whatever is grabbing the
> peak is slower than the attack.  There is no overshoot that I can discern
> with my ears, as the firmware must be dropping audio into a buffer and
> setting the response in kind.  I once heard people complain about delay in
> the monitor, I do hear a very slight one.  So there must be a look ahead
> buffer that computes the response to the peak.  All I'm saying is that it
> would be nice to have a handle on at least the decay, so it can more match
> the attack.  Probably cant do that as it would create more delay in the
> monitor.  It's a fine line.
>
>>
> "What I was suggesting is an AGC funtion before the RF Clipping section
> touches the audio waveform.  Something to smooth out the dynamic range of
> the audio input so that the DSP processing engine would not have to work so
> hard dealing with peaks and valleys and can be "let loose" some."
>
> Elecraft is already accomplishing envelope leveling and shaping with digital
> functions that don't appear to >resemble the sledge and wedge of RF clipping
> and AF variable band amplifiers. SOME folks get excellent results using the
> K3's leveling and shaping processes for TX audio.  I would hate to bring up
> RTFM on setting up K3 mic gain and compression, but the manual procedure
> does seem to work.
>>
>
> I would like to get a better understanding of the process that is used here.
> I do use the manual settings, It does work well, and does sound good, but I
> would like to understand what is happening under the hood better so I can
> better adapt to what this rig likes to hear, which, to me, is consistent
> levels.  My old admittedly analog rig was less picky and had much more room
> to play with (when I let it).  Hopefully that is not Elecraft Secret Sauce.
>
>>
> AND, since there is NO analog audio band circuitry in there anywhere, BUT
> there ARE banded TX and RX equalizer functions being done in the number
> soup, whose gains are being set by NUMBERS we enter in the menu, what makes
> us think he hasn't already done something proprietary about "banded gain"
> which he is developing further and is not about to reveal so the competition
> can't copy it for free?
>>
>
> This is probably the Secret Sauce I'm talking about.  Are you implying
> 8-band digital split band processing?
>
>>
> You should have seen the look I got from the oldest one when I asked him if
> the audio actually went through all the slide pots on one of those big
> digital mixers he was running, the look that says "Please don't talk like
> that when my friends are around."
>>
>
> That's pretty funny.  On my side, the video side, I was explaining to a
> pretty hot non linear editor how we did non-b-roll match frame editing with
> timecode on helical composite VTR's and the importance of the color frame
> sequence across 4 fields (360 degrees of subcarrier and matching subcarrier
> to horizontal sync) so that the picture wouldn't jump at the match frame in
> NTSC.  Couldn't understand the process!  Couldn't even begin to understand
> true A/B rolls either.  So I know what you mean.
>
>>
> there is no K3 RX AF analog circuit controlled by AF gain.  There is no K3
> RX RF analog circuit controlled by RF gain. The AF and RF pot settings are
> immediately turned into "advice" numbers and passed along to the MCU.
>>
>
> Advice in the way of a VCA setting?  Wonder what the granularity is.  It is
> an analog pot, so logically we read a voltage and digitize it, then report
> it to the MCU.
>
> Thanks for pointing me in the right direction, Guy.  Now I know the probable
> true reason for the annoying "cant talk to the RX controls while in TX"
> behavior.  A hybrid Parallel/Serial signal bus.
>
> I'm afraid I pushed paper from the left side to the right side of a desk for
> way too long.
>
> -lu-
>
>
>
>
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