Discrete Quad FM Test Station (KPEN/KIOI)- some station history w/stereo

[kfbkfb]

https://bayarearadio.org/audio/kpen/1962/KPEN_Gabbert-Excursions_c1962.mp3
IIRC, Louis Dorren called James Gabbert to try to get his newly invented Discrete Quad FM system OTA for testing (it was).

IMHO, too bad the FCC waited till the early 1980s to approve the Dorren Discrete Quad FM system.

I listened to this w/DPL decoding, there was some sound routed to surround.


Kirk Bayne

 

[kfbkfb]

I just sent a message to the Bay Area Radio web site to please add info about the Discrete Quad FM tests on KIOI (using the Dorren system).


Kirk Bayne

 

[fizzywiggs41]

At one point (probably 74) no less than 33 stations were involved with Discrete broadcasting/tests in the
San Francisco/San Mateo area.

I also found it interesting that KIO1 Frisco also tested the G . E . Discrete system .

And being a strong proponent of Discrete Broadcasting and CD-4 , it's no surprise that James Gabbert owned K 101 San Francisco .

See the attached from the Soundbird CD-4 Test Disc.




%)

 

[kfbkfb]

I had read that Louis Dorren just picked up the phone and called KIOI (seemed rather brash ) to try to get his Discrete Quad FM system tested OTA, now I know why he picked KIOI [a well known "audiophile" FM station], I guess sometimes you have to be brash to get things done.


Kirk Bayne

 

[Soundfield]

https://bayarearadio.org/audio/kpen/1962/KPEN_Gabbert-Excursions_c1962.mp3

Very interesting broadcast from the early multiplex stereo days. I wonder what the point of the brief 5 second burst of a 1Khz tone was – difficult to do any sort of tuner alignment in 5 seconds!

The BBC used to transmit test tones for channel ID and crosstalk measurement for several minutes after the closedown of Radio 3 five nights a week. Two nights a week it broadcast a longer and more comprehensive suite of tones. An information sheet with advice on tuner alignment was available-

 

[kfbkfb]

Maybe it was an attempt to give KPEN some audiophile cred, possibly combined with a top of the hour indication.


Kirk Bayne

 

[Soundfield]

The odd thing about the BBC test transmissions was who were they really aimed at? They were known as "Trade Test Transmissions" but who in the 'trade' was up at midnight aligning tuners? Very few I'd have thought (think of the overtime!). They carried on for some years though.

 

[par4ken]

The odd thing about the BBC test transmissions was who were they really aimed at? They were known as "Trade Test Transmissions" but who in the 'trade' was up at midnight aligning tuners? Very few I'd have thought (think of the overtime!). They carried on for some years though.

True enough but that would of been the only time to broadcast such tones so that the general audience wasn't affected. The only other time would be very early in the morning before regular programing begins. Kind of cool that such tones were broadcast at all!

 

[kfbkfb]

I didn't get a stereo FM radio until 1984-07, a walkman type (~$15, battery power only, stereo headphone jack only).

Prior to this, I listened to FM on mono portable radios and clock radios (I could hear the audio processing on KBEQ FM [early 1970s] and KIIK FM had a continuous audible level of hiss [early to late 1970s]), due to my experience with the poor sound quality of the FMs I listened to, I didn't buy a home audio stereo FM radio until 1989-09 (as part of a Pioneer SX-2300).


Kirk Bayne

 

[Q-Eight]

There used to be a reel recording of one such test done on July 24, 1976.... it even made the rounds as a DVD conversion and it featured roughly 45 minutes of such a radio broadcast. They had a host in each corner of the room from the four stations involved.... the stations off the top of my head....K101 was one of them, KBRG San Francisco was another.... and KZAP and KSFM Sacramento. It was pretty cool and I'm glad somebody had the forethought to record it over the air. You would hope a master recording would've been done and either Mr. Dorren or Mr. Gabbart would've kept it. Who knows?

I assume, just from the stations involved, they were using the Dorren system and listeners may have required that groovy little FM box we discovered a few years back. I'm not 100% exactly sure how it went down, but they describe it as the first discrete Quadraphonic FM broadcast.

 

[kfbkfb]

https://kq4.blogspot.com/2006/02/dorren-quadraplex-dead-end.html
I thought the FCC was asked to approve the Dorren Quad FM system wo/testing, but they didn't approve it citing possible interference issues that needed to be resolved (Louis Dorren provided the info as to when his Quad FM system was approved by the FCC).


Kirk Bayne

 

[Q-Eight]

Read at the very bottom of the page you posted:


On August 1, 2007, I received this from Lou Dorren: "We actually won as the US national standard. It took the FCC so long to approve (March of 1986) that the industry was already dead!"

 

[kfbkfb]

Yeah, I thought it was approved in 1983, too bad they didn't give other FM stations STAs to broadcast (Dorren) Discrete Quad, it might have helped popularize Quad.

https://en.wikipedia.org/wiki/KIOIKIOI was sold for ~$12 million in 1980 (~$40 million in 2021), maybe us QQ members can gather up our spare change and buy the station from iHeart and put Discrete Quad OTA (again), the Dorren system is still the (USA) standard.


Kirk Bayne

 

[atrocity]

I assume, just from the stations involved, they were using the Dorren system and listeners may have required that groovy little FM box we discovered a few years back. I'm not 100% exactly sure how it went down, but they describe it as the first discrete Quadraphonic FM broadcast.

Simulcast. I listened via KZAP/KSFM. Can't remember which was the front and which was the rear, only that I had to settle for stereo from one station and mono from the other.

 

[Electric Moo]

Simulcast! That's a word I have not heard in a long time

 

[MidiMagic]

Even if they make the station quad, you still have to find a receiver. Nobody makes them.

 

[kfbkfb]

True, maybe get a vintage Quad receiver with an FM detector output (intended for the Panasonic/Dorren decoder mentioned in an earlier post), record the output of this FM detector output into a PC and decode it with software (much as the Stereo Lab CD-4 decoder works, although Dorren Quad FM software decoding would be much easier).


Kirk Bayne

 

[kfbkfb]

The Dorren Discrete Quad FM system could have been used worldwide (the only change would be the preemphasis in the LF+RF+LB+RB [mono] signal, in some areas, 50 microseconds EQ instead of 75).

I wonder why the BBC developed Matrix H when the Dorren system had proven itself viable (NQRC tests in 1975)?


Kirk Bayne

 

[Soundfield]

I wonder why the BBC developed Matrix H when the Dorren system had proven itself viable (NQRC tests in 1975)?

Several reasons I'd venture-

1. Cost to the BBC (i.e. the tax payer). In 1975 the BBC were still only in the early days of their stereo roll-out. To change that to a nationwide discrete quad system would have been fabulously expensive.
2. Cost to the public. In the 1970s high quality stereo tuners were very expensive. Adding at least another 50% to the cost price for a discrete 4ch tuner would not have been a winning strategy.
2. Questionable performance. The BBC would have wanted to test the system under real world conditions in the UK. There were plenty of concerns around the necessary signal strength and the poor signal to noise of multiple sub-carrier systems.
3. There was no proven demand. Stereo was not widespread (see 1) and there was even less knowledge or interest in quad. The BBC was not convinced of the value of quad and its test transmissions of Matrix H were simply that. They were gauging both technical performance and public acceptance. Matrix H was not a great leap forward technically and the year long tests passed off without most of the public noticing or even caring about quad in any form.

Difficult to argue that the BBC got it wrong.

 

[MidiMagic]

The Dorren Discrete Quad FM system could have been used worldwide (the only change would be the preemphasis in the LF+RF+LB+RB [mono] signal, in some areas, 50 microseconds EQ instead of 75).

I wonder why the BBC developed Matrix H when the Dorren system had proven itself viable (NQRC tests in 1975)?


Kirk Bayne

By 1975, they had discovered that most of the discrete 4-channel open reel tape machines were going into home music studios (as multitrack recorders), not quadraphonic systems. These sales were the reason manufacturers thought quadraphonics would sell big.

Every Q4 machine I ever saw was in a home studio.

When the manufacturers found this out, they discontinued everything quad. A few (e.g.TASCAM) kept making the recorders as multitracks.