[lukas44]

OK, I don't know if it was ever mentioned before, about a car radio's tuner.
A long time ago, an audiofile friend of my father commented what few people know, that a car radio's tuner is more advanced than a home tuner, because it has to pull in signals from the most adverse & continuously changing conditions. He used a car radio's tuner for FM in his home stereo. My father (a serious audiofile at that time, when tube popularity was the starting to give in for transistors) joked and dissmissed the thought.

About 1&1/2 years ago my father read an article in a smaller Hi-Fi publication and was reminded of this topic. They reviewed/compared a car stereo as a home stereo tuner. But this was no ordinary car stereo. A new technology which is shocking overlooked from being revolutionary, in which the tuner section recieves & decodes the FM signals TOTALLY in Digital domain. This totally bypasses all forms of distortion/interference that is common to the RF/anolog decoded signal stages, which is how all FM tuners operate, even though on most modern tuners today you see a digital display in which stations are digitally tuned/locked, & has digital presets, so you are fooled into thinking it is all digital. Remember we are talking about the tuner's capturing & processing a multiplex FM signal to an anolog source line-out.

This new technology on this car radio's FM tuner made it much better at recieving clean signals than most, and the magazine reviewers were impressed to see specs better than they had ever seen. They could not even overload it with a strong FM signal that would send other tuners into overload/distortion. Then came the comparison to Audiofile tuners, in which it BETTERED their reference tuner. They then said that this unit is too good to put in a car!

My father bought the car radio, bought a 12v power supply for it, and tested it against his $1,000 Magnum Dynalab FM tuner which I also compared. The end result was he gave me his tuner and made this car radio as his new FM source for his HI-Fi system.

I am still shocked and always find it hard to believe that such unbelievably high quality FM sound can come from such a small non-HiFi unit. It is all in the technology, and proving also that that old guy from many years ago was right, that car FM tuners are more advanced than home stereo units.

Anyway here it is:
ALL BLAUPUNKT car recievers with what they call their "DigiCeiver" all-digital AM/FM tuner! Use the "preamp out" to your home stereo.

This is an Audiofile secret that the HiFi stores & mags will dismiss, but is very true!

 

[mkmelt]

An automobile is not the ideal place for FM reception because the vehicle is usually in motion, encountering varying signal reflections from buildings and interference from all sorts of RF sources including the ingition system of the car itself and also nearby vehicles.

Car stereo manufacturers have added features to car stereos that can improve FM listening on wheels that may not be as appropriate for a home system. For example:

High Blend Circuits: Many car stereos automatically blend the high frequencies on all but very strong signals, to keep static and noise from becoming a problem. As more of the high frequencies are blended into the center channel, stereo separation is sacrificied, until just the mono signal is left.

Automatic Antenna Switching:
One of the latest improvement in FM radios in automobiles has been the use of two separate antennas (one with vertical orientation and the other horizontal, embedded in the rear window of the vehicle. This eliminates the need for an external mounted mast that can be damaged. These dual antennas are then connected to amplifiers and finally to the car stereo receiver that automatically analyzes the quality of the signal from each antenna and switches to the one with the least interference (multipath) or other noise/distortion. The switching takes place in milliseconds and the listener is never aware that the tuner is constantly evaluating the antenna signals and using the best one.

Cars are just noisier than a home environment, so while 50 db of signal to noise in a home system would be mediocre, in a car system this level of performance is very usable because the background noise level in the car is probably at least 65db if not 70db or higher.

Audio that is being played at a level much lower will not be heard over the road noise (engine noise, tire noise, and wind noise).
Any audio program with more than about 35 db of dynamic range will be too loud during the loudest passages and too soft during the softest passages to be enjoyable,without constantly adjusting the volume up and down.

Most FM broadcasts are highly compressed to where they probably have no more than 15 or 20 db or dynamic range in them anyway, because the stations know their primary listening audience members are mostly in vehicles. Some classical and jazz stations do not use nearly as much compression of their audio as the rock and pop stations.

I have no doubt that a Blaupunkt or other car stereo receiver can sound very good when hooked up to a home system, but with a good antenna (you did not say what type of antenna was used with the Magnum Dynalab tuner) the analog tuner will be a good performer too. Many times, people hook an expensive tuner or receiver up to a $2 dipole antenna without even any regard to properly orienting the antenna for best reception, then blame the tuner when they are disappointed with the results.

The really great FM tuners are all analog, and many of them are tube based. At some point specifications become useless when comparing audio components. It's about recreating the sound of real musical instruments or human voices and a good analog tuner is better at being able to recreate the experience of a live classical, jazz, or choral performance in the home.

 

[kevin gilmore]

quote
ALL BLAUPUNKT car recievers with what they call their "DigiCeiver" all-digital AM/FM tuner! Use the "preamp out" to your home stereo.

I don't believe this for even one second.

Digital phase locked oscillator in the first stage which
takes many input signals and converts them to 10.7 mhz,
this i believe. The amount of money it would take to actually
digitize at the native frequency of 100mhz and then the
horsepower necessary to digitally decode the fm would
certainly not fit in the receiver, let alone the car.

Same thing with the 10.7 mhz. Now one more stage down,
i.e. 455 khz, this is getting to be almost believeable. Digitizing
this frequency is certainly possible, although still fairly expensive.
Once again the amount of dsp necessary to decode this
data would also be the size of the car.

Maybe just maybe they digitally sample the 0 to 20khz audio
demodulation, then do the L+R, L-R calculations at reasonable
dsp rates. This might have some merit including better seperation.

 

[zimmer]

I remember the article - It was in Audio Critic maybe even their latest issue. Their publication has been very sporatic in the past few years. Not a publication that would be very popular with alot of folks around here - very Objectivist in viewpoint.

 

[lukas44]

OK naysayers:


mkmelt:
Quality stations like classical, jazz, & city stations do not compress the signal as you say, like pop stations due, which is oly one aspect of the FM signal. Multipath & other forms of noise are more noticealble.
Both units used exact same, high quality ant souce with outside antenna similar to what motor homes use, and also was using Magnum Dynalab pre-tuner which tunes & boosts the frequency which was fed to both. The signal was fairly clean, with the Magnum tuner's meter reading a slight modulation noise, and as you say, aside from specs it came down to the sound. The Blaupunkt had no noise at all(Magnum had a very slight distortion in highs), a deeper overall soundstage and had clearer low freq. resolution. Both sounded alive & excellent in normal use, as the differences were not large, but still noticeable enough(depending on your system) in critical listening...


kevin gilmore:
You must read the company's explanation on exactly how they digitally decode the FM signal. I am sorry I don't have that information to post for you.
There is no sampling/encoding being done, so your speculations on what it takes, for your way of doing a digital tuner, is out of the topic of our discussion.You are right to not believe that view.
As for me I was there and my ears told me the bottom line. I am not kidding you when I tell you this machine sounds better than the Dynalab, or any lower HiFi tuner. My father has the "Calablanca" version which is discontinued, but the same technology is in the newer lines.

zimmer
You may be right as to the magazine name, as I can't recall the name of the magazine for it was over a year ago.
I don't know what you mean by "Objectivist in viewpoint", but the magazine I read (if that was it)struck me as very "real & down to earth". You can't get that with most magazines in US because they cater to expensive products(like Stereo Review). I find magazines from UK to be more truthfull and "down to earth". They compare expensive with the lower, and don't dismiss any product because of price.

 

[mkmelt]

I do not consider any antenna with a booster or amplifier to be an acceptable solution for the best possible sound. Tuning the antenna can improve the quality of the received signal, however, anytime you amplify the signal you are also amplifying any noise that is present along with the signal. So I would only consider an antenna amplifier as a last resort.

Sadly, there are few high quality FM-only antennas made today as many people do not have the option or choose not to mount a dedicated FM antenna to the outside of their home. So most FM listening is a compromise solution, with the antenna and signal quality being sacrificed for convenience or lackof other options.

If you are fortunate to live within a reasonable distance, say 30 - 40 miles from a good broadcast location, even a properly oriented dipole antenna will reward the listener with some very good FM listening.

I do however like the approach of using a car stereo as a home receiver/tuner. It is right in line with my penchant for using technology for purposes other that for what it was originally intended.

 

[lukas44]

mkmelt is totally correct on this point, as I have seen the both the signal and "multipath noise" meters increase if I turned up the ant amp part of Magnum Dynalab pre tuner, but the tunning knob is a nice feature, which lets you tune to a FM freq before ant is fed to tuner, thus helping tuner select with less interference. A nice component for any tuner.

 

[orl2222]

Another option is satillite radio. I have both XM and Sirius installed in my car, as well as a Delphi Xm unit for my home. I don't listen to FM radio anymore. Its got better sound, and to me is well worth the 9.95 a month.

I've actually hooked up an old car radio in my garage several years ago, it sounded good, but was just connected to some old car speakers I've had.

 

[sliberman]

Quote:

Originally posted by kevin gilmore quote ALL BLAUPUNKT car recievers with what they call their "DigiCeiver" all-digital AM/FM tuner! Use the "preamp out" to your home stereo. I don't believe this for even one second. Digital phase locked oscillator in the first stage which takes many input signals and converts them to 10.7 mhz, this i believe. The amount of money it would take to actually digitize at the native frequency of 100mhz and then the horsepower necessary to digitally decode the fm would certainly not fit in the receiver, let alone the car. Same thing with the 10.7 mhz. Now one more stage down, i.e. 455 khz, this is getting to be almost believeable. Digitizing this frequency is certainly possible, although still fairly expensive. Once again the amount of dsp necessary to decode this data would also be the size of the car. Maybe just maybe they digitally sample the 0 to 20khz audio demodulation, then do the L+R, L-R calculations at reasonable dsp rates. This might have some merit including better seperation.

The Blaupunkt digital car radio was jointly developed with Motorola, a few years back.

Motorola has a new chip set for digital car radio. It digitizes the
analog RF signal at the 10.7MHz intermediary frequency.
More details about the new digital chip set can be found at
the Motorola site.
A link to one of the documents: http://e-www.motorola.com/files/rf_i...HONYCHPSET.pdf

Sergio