[Elecraft] OT (Yamaha Cm 500)

[Alan Bloom]

Thanks guys.  

> Yes, I agree that Alan is doing way too much cut on the low end.

I should have mentioned that the microphone is a computer-type headset
with a boom mic, which probably has no frequency shaping at all.  Plus I
have a rather deep voice so, between those two factors, I no doubt need
more bass suppression than most.

> Also a response to Alan's suggestion of tuning for flat spectrum on the 
> display.  IF, and ONLY IF, the spectrum display is providing a VERY FAST 
> and very reliable peak and hold response, that is a potentally useful 
> way to START. The problem is that most displays are averaging,

I was using the peak mode on the P3 with averaging turned off.  The peak
is basically instantaneous, limited only by the bandpass filter in front
of the FFT, about 4 kHz (+/- 2 kHz from the RF center frequency) at the
narrowest spans.  The hold time is infinite until you manually reset it.

> But it is NEVER wise to depend 
> only on any form of spectral response display to set EQ. The final test 
> instrument must always be our ears and the grey matter between them.

I should use the K3's DVR to send a test signal and listen on my TR7.
The thing is, listening is so highly subjective that I figured that I'd
get better accuracy using a spectrum display.

Alan



On Tue, 2010-11-16 at 23:00 -0800, Jim Brown wrote:
> On 11/16/2010 10:19 PM, Joe Subich, W4TV wrote:
> >   >  I ended up with:
> >   >
> >   >  50 Hz   -16 dB
> >   >  100 Hz  -16 dB
> >   >  200 Hz  -16 dB
> >   >  400 Hz  -10 dB
> >   >  800 Hz  -16 dB
> >   >  1.6 kHz   0 dB
> >   >  2.4 kHz  +3 dB
> >   >  3.2 kHz  +6 dB
> >
> > I think that is doing too much cutting at the low end and not
> > enough boost at the high end.  Adding 6 dB at each band from
> > 200 Hz to 3.2 KHz would make me more comfortable.  Like, Jim
> > I prefer to leave 50/100 at -16 regardless as they contribute
> > nothing to communication.
> 
> Joe,
> 
> Yes, I agree that Alan is doing way too much cut on the low end.
> 
> I meant to respond earlier to your recommendation of high boost.  I've 
> helped a LOT of K3 users adjust their TX audio using a CM500, and I've 
> NEVER heard a CM500 that needed ANY boost EQ.  I've also gotten a lot of 
> very positive reports on my CM500s (I own two) and I've never used any 
> boost.
> 
> So I started thinking about why you might like boost -- after all, 
> you're a pretty sharp engineer. I can only come up with three scenarios 
> where you might prefer that. The first scenario is IF bandwidth on the 
> listening station.  I always listen to the other station with my IF 
> bandwidth at about 2.7 - 3 kHz, because I don't want what MY RX is doing 
> to color my judgment of what the other guy is transmitting. So I get him 
> sounding good that way, and THEN I narrow up my IF to 1.8 kHz and listen 
> again.
> 
> IF you listen at 1.8 kHz bandwidth with the high end of the IF cutting 
> around 2.4 kHz or below, you certainly ARE going to want a bit of boost 
> on the high end, because the RX IF is rolling it off.. But if you center 
> that IF a bit higher, you won't want that HF boost.
> 
> The second scenario is that since CM500s are pretty inexpensive 
> products, there may be a fairly wide tolerance on the response of the 
> capsules.  I've seen some anecdotal observations that suggest this might 
> be true.  I DO believe, however, that the CM500s I own, and those I've 
> helped set up on the air, do NOT need HF boost.
> 
> The third scenario is hearing loss.  We old farts have put a lot of 
> mileage on our ears, I know that I've got some hearing loss, and so do 
> many of my friends my age, especially those of us who work with audio or 
> radio professionally, or even as active hams.  The nature of MOST 
> hearing loss is that we lose the high end first, so we want more high 
> end boost.  I find that I need to do that with many news magazine and 
> interview programs that have poorly produced audio. I find it 
> professionally disgusting that the technicians who produce these 
> programs have the balls to call themselves engineers when they obviously 
> don't know what an equalizer is for or when to use it. But don't get me 
> started. :)
> 
> The reason I'm going through this is that I hear so much badly distorted 
> audio and splatter during contests, and the LAST thing that we need is 
> HF boost to produce more of it when the mic is already providing that 
> boost, and the CM500s I've heard DO have that HF boost built in.
> 
> Also a response to Alan's suggestion of tuning for flat spectrum on the 
> display.  IF, and ONLY IF, the spectrum display is providing a VERY FAST 
> and very reliable peak and hold response, that is a potentally useful 
> way to START. The problem is that most displays are averaging, and the 
> average power of human speech is greatest in the lower octaves, so an 
> averaging display should NOT look flat. But it is NEVER wise to depend 
> only on any form of spectral response display to set EQ. The final test 
> instrument must always be our ears and the grey matter between them.
> 
> 73, Jim Brown K9YC
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html