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KBAQ Phoenix - is noise due to IBOC from HD Radio?

192.88.158.215
Posted on February 13, 2012 at 13:15:12
openmind
Audiophile

Posts: 184
Location: Phoenix
Joined: November 8, 2008
 In Chandler I get a strong signal from both KBAQ and KJZZ but KBAQ is noisier. The noise goes away in mono.

I've experienced this on both tube and solid-state tuners, three of which are freshly aligned. I'm suspecting in-band-own-channel noise due to HD radio, but I don't have the instrumentation to confirm this. If any RF experts out there have data, I'd really like to know. I'm planning on building an FM decoder and the design depends on the answer.

I wasn't listening to FM much when HD radio got turned on; did anyone in the Phoenix area notice a change? Please let me know.

I've volunteered for both stations, they're in the same building; I don't
believe the source quality is different. KBAQ's online stream is quiet but not the high bitrate I would like.

Have others experienced this problem with KBAQ? Another FM user here in the East Valley reports KBAQ is noisier on several tuners he has tried. Another user in Pinnacle Peak says he does not have that problem.

Thanks for your observations!

Regards, openmind

 

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RE: KBAQ Phoenix - is noise due to IBOC from HD Radio?, posted on February 14, 2012 at 08:08:25
FRG7SWL
Audiophile

Posts: 2116
Location: NorCali
Joined: March 26, 2003
 Openmind, here's a chart of HD stations in the Phoenix area. On Sactown's local medium wave band, KFBK's HD sideband on 1.530 Mhz drowns out reception from 1.510 Mhz to 1.150 Mhz. Wonder if KSEG's two HD sidebands on 96.9 Mhz nullifies formerly clear reception of Nevada City's KVMR analog 89.5 Mhz signal in North Sac-n-Natomas? KSEG's transmitters are located near Northgate Blvd off Hiway 80, right in the heart of that null. 73s from Sactown!!!

 

RE: KBAQ Phoenix - is noise due to IBOC from HD Radio?, posted on March 17, 2012 at 17:11:30
bruceontheice


 
Hi All,
Yes, the noise is due to the IBOC digital carriers. And, probably the carrier from the upper first adjacent station near KBAQ's frequency having IBOC as well. here is a link to an article intended for FM station engineers guiding them to a choise of IBOC operating power. A bit technical, but it does explain the noise you are hearing in good detail. The problem is that there is no easy way to get rid of this noise available to the consumer.

http://www.rwonline.com/article/look-before-you-leap/4804

Best regards

 

RE: KBAQ Phoenix - is noise due to IBOC from HD Radio?, posted on March 17, 2012 at 17:53:05
Neff


 
You can always call the radio station. HD noise is nasty and usually worst sounding than mild multhpath. Changing to mono is a good indication the station is using HD on the transmitted bandwidth skirts. Some stations are also out of compliance with extra wide HD bandwidth making the matter worst. Most stations cannot afford a good in-house tech nowadays either. Tuners with a narrow IF bandwidth (not the best sounding in narrow) or a HD immune multiplex decoder is the best bet. Some tuners use a post detector, but I do not test all designs. Google HD Radio Self Noise for more info.

If you go for an immune by design multiplexer, forget the Pioneers. The F-90 rated fairly good at fmtunerinfo is a sonic disaster even after upgrades. Ya, I had an aligned unit as I perform alignments for years.

Anyways, the Kenwood KT-990D is a seriously good sounding if a tad laid back (super smooth) sounding tuner. It is as clear sounding as a bell. The Rotel RHT-10 is excellent, but not inexpensive.

 

RE: KBAQ Phoenix - is noise due to IBOC from HD Radio?, posted on March 17, 2012 at 18:58:45
fredtr
Audiophile

Posts: 2117
Location: Phoenix
Joined: January 4, 2005
Contributor
  Since: August 16, 2024
 I'm a KBAQ fan. I haven't had a problem with noise on KBAQ. I listen to it so much that I have tried a number of tuners to find one I like, and noise hadn't been an issue with any of them. I'm currently using a Scott 310E, which I recommend.

 

RE: KBAQ Phoenix - is noise due to IBOC from HD Radio?, posted on March 27, 2012 at 10:39:15
openmind
Audiophile

Posts: 184
Location: Phoenix
Joined: November 8, 2008
 All:

Thanks for your responses, I hadn't looked at this post in a while. I appreciate it!

Tuners that are quiet on KBAQ: McIntosh MR-77, Blair-modified Scott 370 (tube), Pioneer F-91;

Tuners that are noisy on KBAQ: Updated and aligned Dynaco FM-3, McIntosh MX-130, Harman-Kardon TU 920, Sony ST-S550ES, freshly aligned Harman-Kardon Citation IIIX.

Last time I looked online, KBAQ/KJJZ had an opening posted for a station engineer. Somebody please take the job and fix it! Thank you!

 

RE: KBAQ Phoenix - is noise due to IBOC from HD Radio?, posted on April 6, 2012 at 10:14:51
mcgjohn@yahoo.com
Industry Professional

Posts: 501
Location: Midwest
Joined: February 5, 2008
 Its been a number of years since I lived in the valley; but used to listen to both. KBAQ used to have a very low power signal. much lower than KJZZ. In the late 80s or early 90s, I believe KBAQ was able to increase their transmitting power from 4KW up to 12KW.

And even though both stations are in the same bldg, I believe their transmitters are in different locations.

You did not mention what you were using for an antenna to pull in either station. R. Shack used to sell a 6 ft FM antenna for 29 bucks. That worked quite well.

best

J

 

RE: KBAQ Phoenix - is noise due to IBOC from HD Radio?, posted on April 6, 2012 at 15:14:42
openmind
Audiophile

Posts: 184
Location: Phoenix
Joined: November 8, 2008
 Hi, thanks for the suggestions. I'm using an "outdoor" antenna about six feet long mounted in my attic. According to fmfool.com, both stations are transmitting from a location almost due west from me. KBAQ is 16 kW; KJZZ is 100 kW. Both are 12 miles from my home. I don't have an absolute signal strength number at my tuner; I think both stations light up all the signal-strength LEDs on my MX-130. KBAQ has three HD transmissions; KJZZ has 2.

Dynamic range is critical on classical music! For comparison I will again check out KFLR which is broadcasting with only 5 kW from the same location.

Thanks!

 

RE: KBAQ Phoenix - is noise due to IBOC from HD Radio?, posted on April 7, 2012 at 10:05:24
openmind
Audiophile

Posts: 184
Location: Phoenix
Joined: November 8, 2008
 KFLR with 5 kW lights up 8 signal LEDs on my tuner but is quiet; KBAQ with 16 kW also lights up 8 LEDS but is noisy. KBAQ did raise funds a few years ago and get a new transmitter.

Fortunately I have a chance to participate in a member survey and will pass along my experience to the station.

Thanks very much to bruceontheice for the thorough technical article.

 

Quiet MPX decoder, posted on April 19, 2012 at 10:49:41
openmind
Audiophile

Posts: 184
Location: Phoenix
Joined: November 8, 2008

There is an outboard MPX decoder which you can read about here:

http://groups.yahoo.com/group/fm-mpx/

I hooked one up to the composite output of my Citation III-X tube tuner and it is very quiet on KBAQ.

 

RE: Quiet MPX decoder, posted on June 10, 2012 at 17:33:18
bruceontheice


 
Hi All,

The hiss on KBAQ-FM really was driving me crazy. So, I built up a multiplex demodulator based on the LM-4500A and installed it into my aging Realistic STA-2000 receiver. This indeed takes care of much of the hiss problem. Next will be the installation of a better antenna system. I live in an apartment, so it can't be too large. But it really needs to be outside to work well.

I couldn't afford the nice board that Bob Fitz makes available (www.FMMPX.com) so I built it on a clad perf board from Radio Shack following the basic information on the National Semiconductor datasheet. It looks really home-brew but works and sounds great.

I hope that this helps someone get cleaner sound from their tuner or receiver.

Best regards,
Bruce Sherman
"bruceontheice"

 

RE: KBAQ Phoenix - is noise due to IBOC from HD Radio?, posted on January 18, 2024 at 12:18:02
openmind
Audiophile

Posts: 184
Location: Phoenix
Joined: November 8, 2008
 The FM tuners group that was on Yahoo has moved to groups.io but is better than ever. Mr. Fitzgerald has designed an add-on post-detection filter board, but implementation requires some level of test gear to adjust the notches, like a scope, counter, and function generator (to 200 kHz). If it becomes widely available, it may save a lot of tuners from the landfill!

 

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