Say no to hi fi audio for communications

[w3jn]

Sam, as you can see, you kind of got off on the wrong foot here.  You are free to hold, and thanks to Gary's generousity, express, your opinions freely here.  However to speak in absolutes as you do is to pretty much destroy your case.

Here on the East Coast there are many tall ships (running LEGAL power) who offer full quieting signals, and it's a pleasure to listen to them and appreciate all of the attention they have paid to well-tailored, low distortion audio.  If you take some time to explore the site and look at some of the posts and longer articles, you'll see that many here have modified receivers capable of hi-fi audio, take extreme care in engineering audio chains, and take the proper measures to ensure their signals are free of splatter and distortion products.  For many here that is one of the prime attractions to AM; for you to dismiss it completely is rather out of order.

Not everyone can, or even should, homebrew.  It's fun, I enjoy it (I built a homebrew hi-performance receiver and a tube audio amp that rivals $5000 store bought amps), but is not the be-all/end-all.  Again, by dismissing those that use "slave labor" radios, you are dismissing many fun and interesting people - people who are experts in perhaps other areas of radio.

If I might make a suggestion, take a look around the site and get a feel for what we're all about.  Every one has opinions - yours is important too - but how about discussion rather than statements and absolutes?

BTW bandwidth isn't "consumed" or "used".  As WB3HUZ pointed out in another thread, it's there for anyone to use after I'm done with it 

[Tom WA3KLR]

In the ARRL's RM-11306 proposal, the 9 kHz for AM use was in NECESSARY bandwidth.  That was not stated in the petition, but I got this directly from Ed Hare, ARRL Lab Manager about 2 months ago.

[k4kyv]

In the ARRL's RM-11306 proposal, the 9 kHz for AM use was in NECESSARY bandwidth.  That was not stated in the petition, but I got this directly from Ed Hare, ARRL Lab Manager about 2 months ago.

Actually, it was.  See page 11

http://fjallfoss.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6518181567

The recommendations of ARRL ’ s Ad Hoc Digital Committee were to delete the symbol rate limitations in Sections 97.307(f)(3) and (4); to segment the bands below 28.0 MHz by nominal bandwidths of 200, 500 and 2700 Hz as upper limits; and to require that digital data protocols be published, so that they can be duplicated and monitored to protect against intruders. The Committee was aware of the bandwidths and frequency segments under consideration by Region 1 of the International Amateur Radio Union. A bandwidth of 200 Hz was chosen to accommodate Morse telegraphy and the narrowest RTTY/data emissions. A bandwidth of 500 Hz would permit the foregoing modes and a wide range of RTTY/data modes and some image modes yet to be designed. IARU Region 1 studies chose a bandwidth of 2700 Hz for SSB telephony and to accommodate digital voice and higher speed data. The Rules already specify a bandwidth of 2800 Hz for SSB voice in the 60-meter band. As the issue is a maximum regulatory bandwidth, not current practice, which varies from approximately 2400 to 2800 Hz, a bandwidth of 3500 Hz is recommended in the proposed Appendix for the wide bandwidth segments in order to encourage maximum flexibility. The proposed rules also specify that “bandwidth” will be defined in terms of necessary bandwidth rather than occupied bandwidth, to reduce undue concern by operators about determinations by measurement of occupied bandwidth.”

[Tom WA3KLR]

Thanks Don; interesting.  Two years ago I believe I knew the definition of occupied bandwidth but was not aware of the existence and difference of the necessary bandwidth.

Using the necessary bandwidth specification allows people to deal with the baseband audio rather than dealing with r.f.

So according to the ARRL petition then, if you put a 4500 Hz brick-wall low pass filter on your audio preceding the modulator, you would then meet their 9 kHz bandwidth specification.

[Bill, KD0HG]

I would say that most SSB transceiver have a 2.4 to 2.7 kHz NECESSARY bandwidth.  I would venture to say that the OCCUPIED bandwidth of most SSB transceivers is in the range of 3.0 to 3.5 kHz BAREFOOT.  Operation with an additional outboard linear amplifier will further increase the OCCUPIED bandwidth.

The Collins S-Line stuff almost always used 2.1 KHz filters.

[k4kyv]

As I understood it, there would be no strict limit on occupied bandwidth, just as there isn't now.  The 3.5 khz bandwidth would mean that the segment would be open to any mode that requires a minimum 3.5 khz, but might occupy more beyond the necessary minimum.  DSB AM wouldn't fit in, because it fundamentally requires more than 3.5 kHz, hence the 9 kHz exception.

But it might become a subject of debate regarding how much "unnecessary" bandwidth one could occupy beyond the necessary minimum and still maintain "good engineering and amateur practice".  I'm sure some would say that anything beyond the absolute necessary minimum would be illegal under any circumstance, while others might interpret it to mean that one could occupy anything beyond the necessary bandwidth as long as it didn't cause harmful interference.

I'm sure that's a can of worm the FCC would not want to have to deal with, so they might not have agreed to go along with the "necessary" bandwidth proposal and instead, imposed a limit on occupied bandwidth.

BTW the Canadian regulations specify a maximum of 6 kHz bandwidth for AM, but I have never heard of anyone being cited for exceeding that figure, and I don't think the Canadian AM'ers all have brick-wall low pass 3000~ audio filters in their rigs.

[flintstone mop]

The hi-fi audio is not really in super sounding voices. The human male voice only goes down to 100 hz and nothing above 7khz. I might be sounding like an empty barrel, but I thought the bandwidth was in the high freq content. Very rarely do I hear side band slap from a nearby AM Ham station UNLESS they are 5kc away or are having severe modulation problems with a scratchy mic or lousy eq settings. Unfortunately some folks try to adjust their audio using an offshore radio in the LSB mode or are just plain tone deaf. Not everyone enjoys 20-20000hz hearing and can distinguish a nice musical note vs a flat note in music.
You are a musical person like me, Sam and I do not like the muddy bass voices I hear either, but it's their choice and when condx are crumby, I'll tune elsewhere. And where did all this hi-fi audio and using broadcast transmitters come from in the first place...................THE LEFT COAST!!!!!!!!\.........
Seriously, I'm loving AM and there are many new signals on the air this season to prove it.
Fred

Fred

[k4kyv]

The hi-fi audio is not really in super sounding voices. The human male voice only goes down to 100 hz and nothing above 7khz.

Therefore, to avoid undesirable phase shift and preserve your voice waveform and its asymmetry, your audio chain needs to be flat down to at least 50 Hz (one octave below the lowest audio frequency you wish to transmit).  The high frequency response really should go up to 14 kHz, but that's less critical.  If it makes it up to 10K, that should be good enough.  That isn't to say that you have to actually transmit that wide a response, but that the audio transformers and coupling circuits should be capable of passing those frequencies at a relatively flat response without distortion.

That explains why AM broadcast transmitters, from the 1930's on, have touted a flat response from at least 50-10,000 Hz, and often 20~ to 15K, even though the engineers always knew there were few, if any, broadcast receivers out there capable of reproducing that wide a response, that it far exceeded the FCC's minimum requirement for passing a proof of performance, and that under the present rules such a transmitted frequency response, and thus bandwidth, would be illegal.  IIRC, the maximum legal high frequency to transmit has been 7500~ for some time now.

I might be sounding like an empty barrel, but I thought the bandwidth was in the high freq content.

That's true for AM.  Cutting the lows does absolutely nothing to affect bandwidth if the transmitter is producing a clean signal at the outset.

OTOH, W8JI argues on his website that boosting the lows does substantially increase bandwidtth of SSB.  Not that the extra 100-200~ added to the total bandwidth is significant, but that it produces substantially more splatter on adjacent channels due to the poor IMD characteristics of typical slopbucket appliances.  I read this more as a critique of the equipment than of the concept itself of "hi-fi ssb". He mentions that his 1950's vintage Collins SSB rig is much better in that respect.

Remember these rules of thumb for IM3 bandwidth:

The maximum frequency spacing of new intermodulation products is the difference between the lowest and highest pitched tones modulating the transmitter.

The total bandwidth occupied by a SSB signal, when we include IM3 products, is approximately three times the audio bandwidth of the system.

If Tom's claim is valid, what would that say about a 2.7 kHz limit to the occupied bandwidth of SSB? 

http://www.w8ji.com/transmitter_splatter.htm

[ab3al]

did I miss something here.  I may be a johny come lately to the game but I have heard a few things out of the original poster that i cant justify.  I run a flex radio into a good amp.  Yes i can open the bandwidth up to 20k into a dummyload and rival fm stations but i dont on the air. 
I understand what is being said about low end.. heck i can muddy up the signal on my stereo with too much base response.  but all of the ops here have a balanced signal that if conditions were rough all i have to do is tighten up my receiver.. yes my receiver that can recive up to 20k snyc am detection.
as fas as low freq driving up the bandwith.  I know their is flaw im my next statement just take it for what it is.  On both my station and the 2 local mom and pop 1kw biblebeaters that i service  When i plug in my $30,000 spectrum analizer and inject a 100 hz tone only into the transmitter the response is close in to the carrier.  When I insert say a 3k signal is when its starts to get wide.  (At home i pad down the 3k area because thats the center of my blower noise.)  If im wrong tell me and ill call hp and have them calibrate the scope..   By the original posters description  if a broadcast station limited their transmission to 10k (which they do)  they would have no low end response.

my advise.. 
buy a scope and a spectrum analizer and turn them on.. do your high piched p and m into the mic and see what makes for a wide spattering signal.

hey there are lots of guys that have lots of low end mid and high that are exactly 6k wide here on the east coast.  After making their new transmitters they spend a lot of time off air monitoring to make sure the audio chain is balanced for good response and intelligability.

jmho

[WD8BIL]

You operate your station the way YOU want to.  I'll operate the way I want to. Unless you can show me in Part 97 where I'm operating ILLEGALLY your comments are simply ........ interesting.

Low frequency response on AM is difficult to copy if conditions are not perfect. It is unnecessary and uses excessive bandwidth giving fuel to the growing group of anti AMers that have ARRL support.

Think about this more and you'll see the error.
ON A.M., modulating frequencies closer to the carrier create NO additional bandwidth.

AM is all about good clean communications audio.

Please don't define the hobby for me. I'll do it myself.

Thanks to Bob Heil for making these great vintage style mics.

WAIT a  minute..... why buy these great mics when a simple hand-mic will give you the communications audio you asked us all to use.

[WD8BIL]

It is apparently what the majority of this forum considers to be todays AM ham radio and those that don't partake in such interest are looked down on as unimportant and contributing nothing to advancing AM.

Actually, this is totally untrue. The members here are quite inclusive to all who venture into AM. AS with you, many have strong feelings about how they present themselves on the air and work hard to get the sound of their station to represent what THEY want.

To come here and promote the idea; "Say no to hi fi audio for communications" ..... then say we're a closeminded group is unfair... at best.

There's plenty of room for all of us. If advancing A.M. is your true goal then I think you've started out on the wrong foot.

[The Slab Bacon]

All right for want of NOT starting another shitstorm here, I'll drop my 2 cents into the mix. I like the sound of HI-FI aidio WHEN CONDITIONS WARRANT its use. But most and for all, I believe in using well balanced audio. too much bass gets lost in the sauce under bad operating condx, too much highs and midrange (without any bass warmth) makes the ears bleed. You need to have a happy medium there. It does help to have a little high end syballiance in there as well to help differentiate the different consonant sounds, but most of all it needs the proper balance of all of the above.

with well balanced audio you can pinch down the receive bandwidth on a radio thats capable of it (like an r390a) and not lose the intelligibility of what is being said. Excessive bass without any presence rize sounds muddy and unintelligible.

With good operation condx, a full quieting signal should sound like that person is sitting in the room with me! It doesnt get any better than that, short sweet and simple. If they sound like they have a clothespin on their nose, they need some tweaking, if they sound like they are in a 55 gallon drum at the bottom of a well, they need some tweaking as well.

In my personal preference I like the warmth of a big bottom end AKA "3rd ba audio", and many of my receivers will reproduce it easily.
However sybillance out to 15kc is unnecessary as well. the most important thing is to be considerate to the others operating near you.

"Communications quality" audio just plain sucks!! Its fine for bad operating conditions when you neet to "cut through the qrm". But when its that bad, I usually dont get on. If I (and I'm sure many others) wanted to listen to bad audio, we'd be happy to lower ourselves to SSB.

As far as hanging in groups goes, that was/is usually done becaause we are all friends and WANT to hang out together, and/or there is not enough free spectrum available for all to have the luxury of 1 on 1 qsos. Even the slopbucketeers dont do much 1 on 1. Would you want to hang out in a ginmill with all of your friends, or one where there was no one that you know??

For many of us this is also a social thing as well as the techno stuff. For me the big rag chews are kinda like hanging out at the ginmill with all of your buddies, but you dont have to worry about the YL getting pissed off because your home. There are many, many aspects to this hobby, one has to think about all of them before making harsh statements. Life is way too short to be thin skinned!!

YMMV
                                                   The Slab Bacon

[WD8BIL]

The handhelds you refer to are not well rounded communications audio but very restricted and don't reproduce my natural voice,

Now there's an oxymoron for ya... Well rounded communication grade audio.
Comm audio, by definition, is restricted audio. 

So, by what you describe, you like it somewhere between comm audio and broadcast quality. Fair enuf.

[Bill, KD0HG]

There is some benefit in not restricting top end transmitted frequency response.

Doing so provides a degree of pseudo-preemphasis with weak or noisy signals in the analog domain, improving intelligibility, just as has been common practice in audio recording and broadcasting.

There's a reason for it!

One might theoretically not *need* audio response better than telephone grade, but that only applies when the S/N of the circuit is also that of a telephone. There is NOTHING less intelligible over a noisy HF circuit than muffled-sounding audio. The 3.1 KHz filters offered as an option for Collins SSB gear instead of the 2.1 KHz ones are prized by the Collins folks for that reason. Of course, those S-Line filters would be illegal if Rinaldo had his way, too.

[WA3VJB]

Sam are you being a troll, or what?

This started out as a screed against stations on SSB giving a hard time to AMers out your way, and within seconds it became a litany of grievances you have against AMers. So I am suspicious of why you posted in the first place.

There are two quotes I will comment on from your latest posting.

additional bandwidth comes when the audio is cranked over 100% to make up for the bassy signals inability to cut through less than ideal conditions. // it is personal preference and a debate without resolution.

I have never encountered anyone the past 30 years that cranks up their transmitted audio to compensate for poor readability caused by exaggerated bass response. It is counter-intuitive to do so.

The “debate” is actually one of challenging an unfair expression of opinion (yours) that you apparently expected everyone to endorse.

…sense to much hostility where none is necessary. With this I won't comment under this topic anymore as it is not conducive to promoting anything constructive.

I agree.

[WBear2GCR]

My original point was concerning the stations that adjust their equalizers for lows at more amplitude than the midrange. This only causes splatter when they crank up the audio over 100% if no negative peak limiting circuit is used. While a majority of the bass happy operators don't overmodulate, a few do and a few can leave a reflection on a whole group. Naming offenders on a public forum is not right and I refuse to do it. When I hear such operation, I have no problem in telling the operator. Unfortuantly many other listeners don't understand the issue of splatter, don't have scopes, and simply don't care. They have been told this is broadcast audio which is not true, so they encourage this illegal operation (splatter).

Now the second point is my preference and my opinion. I don't like the bass dominated signals because they are hard to copy under less than ideal conditions. If a majority likes these bassy signals, then the majority rules and my opinion doesn't mean jack.

The message I try to get out to newcomers is you don't have to modify your Ranger and you don't have to have all the fancy audio processing equipment to put out a good clean well rounded signal. If you are impressed with all this unnecessary gear and modifications, fine, just learn about it and use it correctly.

Sam,

Your HB station looks very nice. You're not alone in HB'ing around here.
You've got strong competition in that department.

You seem to have not been "sensitive" to a few important distinctions:


1) what you wrote just now, is not the same as what you started the thread with. This is better.
2) apparently you did not take the time to read much or look around this forum very much before posting - "you're preaching to the choir".
3) the questions that I posed to you, you ignored.
4) apparently, based on your post above, it seems that out in SEVEN LAND you have problems with the way some AM ops, or even with the usual way AM ops out there run?? (I asked you this about 2-3 times, btw) Out this way, apparently things are different?
Which is why I asked you about the "EAST COAST SOUND" - you might notice something on this site about that?
5) If (4) is correct, you would do well to restrict your comments to 6 & 7 land?
6) Most of the participants here are not "newcomers" - and while some are, a vast majority of the advice provided here is well balanced and does not suggest the sort of AM operation that you have a problem with.
7) I strongly suggest that you take the time to poke around and look at some of the posts, and some of the station pix that are here - familiarize yourself with it? Many of the ops here have quite broadcast "style" stations, including a wide range of professional mics and processors - while others have vintage rigs that are modified or not. Many, many, many HB rigs. Take a look at W2INR's images (he is the host here) and KG2IR's images. Nick's rig is 100% homebrew, but the rest of the chain is quite professional. Also look at W1IA's and K1KBW's homebrewed class E rigs and stations... don't stop with them... there are swinging links and pi nets, high power and low power, processed and unprocessed, all sorts... familiarize yourself before starting posts??
Many of us are using the "3 diode limiter" which prevents flat-lining the modulation on the negative side... know about that??
9) Relax, you've arrived amongst kindred souls and friends! 

                _-_-WBear2GCR

[Tom W2ILA]

My Valiant is distorted.
My military rigs are pinched and distorted.
My genuine T17 mike through a Simpson 55 marine rig is distorted and pinched (my prototype to 2.1KHz AM).

These rigs will sound hi hi fb om with big bottom end when they are torn from my cold, dead, illegal, radio room.

My (soon to be outlawed) wideband BC rig isn't distorted - its doing its job as it was designed.

Then again, I drive an old car with an unmodified small block Chevy V8.  Should I hack it and install a big honkn newbie 502 crate engine?  Or should it be left untouched as it left the factory 40 years ago even though the Rochester carb smells bad?

73
Tom W2ILA

[k4kyv]

"Communications quality" audio just plain sucks!! Its fine for bad operating conditions when you neet to "cut through the qrm". But when its that bad, I usually dont get on. If I (and I'm sure many others) wanted to listen to bad audio, we'd be happy to lower ourselves to SSB.

That's why it's sometime AKA "space shuttle audio".

[W1RKW]

I saw this thread yesterday but I sat back and waited for the crap storm.  There were a few posts in response to Sam's post that have been removed.  What's up with that?

[W2INR]

Welcome to AMfone Sam!!!

When I mentioned you kicked a bee hive I didn't expect you to smear honey all over yourself

Anyway as you can tell we all DO have many things in common, We all like to build, we all love AM and we all have opinions. That is what makes this site great. We don't always agree and frankly we do not have to but god forbid someone takes a swipe at our mode.


Bob RKW which posts are you concerned with? The ones that Sam pulled or modified or the ones that were insulting, attacking or just plain rude?

G

[Steve - WB3HUZ]

Geez! If that was a concern, the initial post should have been yanked.

[W1RKW]

You're talking to someone who just turned 48. My memory basically stinks. 

There were some posts that were quick jibes, if remember right, so I guess those got pulled. That's OK. Rightfully so. They had no meaning.  So I guess the point is pointless.

Gee Gary, Haven't see you post in quite some time.  Are you supplying the honey? 

Glad to see you're alive and well. Hope to hear  you on the air this winter.

Bustin' Chops Bob

Welcome to AMfone Sam!!!

When I mentioned you kicked a bee hive I didn't expect you to smear honey all over yourself

Anyway as you can tell we all DO have many things in common, We all like to build, we all love AM and we all have opinions. That is what makes this site great. We don't always agree and frankly we do not have to but god forbid someone takes a swipe at our mode.


Bob RKW which posts are you concerned with? The ones that Sam pulled or modified or the ones that were insulting, attacking or just plain rude?

G

[steve_qix]

All I can say is THANK GOD IT'S A FREE COUNTRY (still).  This whole thing about OPINION OPINION OPINION.  It's the League all over again.  The opinions and preferences of a few are trying to be forced on everyone else.

ENTPs of the world unite (and watch out for all those J's out there)!!!!

[W2INR]

Hi BCB ,

I am on almost daily down below 3750. Pretty clear down there and well if the conditions were better it would be more fun.

All I was tying to do was steer the thread towards something more constructive which I think worked - - maybe - - sort of - - I don't know anymore.

I find it interesting that everyone is into HOMEBREWING  but in the poll I have to explain what that means so they won't get confused - - - sometimes I just wonder what the hell I am doing.

Anyway I return this thread to the regular scheduled rants

G

[Steve - WB3HUZ]

I'm an ESPN.

All I can say is THANK GOD IT'S A FREE COUNTRY (still).  This whole thing about OPINION OPINION OPINION.  It's the League all over again.  The opinions and preferences of a few are trying to be forced on everyone else.

ENTPs of the world unite (and watch out for all those J's out there)!!!!