Homebrew Car Cassette Adapter

[olly_k]

This Mickey-Mouse way of playing CDs through a cassette tape player will result in extremely boosted bass and the high frequencies reduced due to the tape playback equalization in all tape players. It will sound awful.

I have to disagree! I have made a proper mickey mouse jobby tape head held in place with plasticine lol - not good on hot days - NO equalisation and was very surprised with the results! The one thing that is essential is the alignment of the tape head if it is slightly out the sound can be pretty bad or only one speaker etc... Stereo separation is great too when set up right!

It was more specifically for my mobile used the original headphone cables with mic still attached so I get calls through car speakers too!

 

[tcmtech]

I'm not sure how the stereo coding is done, or even if it is I don't know how a tape pickup does stereo.

Back in the analog days they didn't code the signals onto the tapes. Its all analog. Its just two side by side tracks that carry the analog signal as variable magnetic information.

Sorry no digital, just moving magnetic dust!

 

[Sceadwian]

There's a big difference between acceptable voice quality and high fidelity music.

 

[audioguru]

There's a big difference between acceptable voice quality and high fidelity music.

Some people have tin ears and cannot hear the difference.
I think voices that have 25dB to 30db of bass boost will be unintelligible.

In 1975 I bought a German Blaupunct radio/cassette for my German car. I ordered its service manual and they crossed out the Chinese manufacturer's name and put Blaupunct with a felt-tipped pen.
It recorded in stereo and I souped it up so that it had low distortion response from 30Hz to 15kHz.

 

[olly_k]

Some people have tin ears and cannot hear the difference.
I think voices that have 25dB to 30db of bass boost will be unintelligible.

In 1975 I bought a German Blaupunct radio/cassette for my German car. I ordered its service manual and they crossed out the Chinese manufacturer's name and put Blaupunct with a felt-tipped pen.
It recorded in stereo and I souped it up so that it had low distortion response from 30Hz to 15kHz.

I sure as hell hope you ain't referring to me with the tin ears !

I will say that I was very surprised with the result. Certainly not HIFI (no such thing in a car anyway) but comfortable listening and NOT bass light or HF heavy at all!

Things change if I turn the in line volume up so perhaps the pot is offering some basic filter function along with the inductance of the tape head, OR perhaps my car stereo has very little equalisation! Not sure tbh!

 

[Sceadwian]

There's also a big difference between being able to reproduce a human voice with clarity, and with accuracy. Just as an example, I use a program called Ventrilo which is like group audio collaberation app aimed at gamers, works great and the compression and quality are top notch, but for giggles one day I recorded what Ventrillo was compressing my voice as. The voice was crystal clear but it sounded absolutely nothing like I do compared to a high quality .wav recording on the same mic.

 

[audioguru]

My car plays FM stereo, CDs and MP3s with high fidelity. That is how a sound system is supposed to be.

My old Blaupunct cassette deck in my 1975 car recorded then played back with high fidelity, after I souped it up.

I hardly ever listen to AM radio, sometimes to hear the new or the weather. It is not high fidelity.

 

[TheNewGuy]

The coil of wire (Mickey-Mouse Circuit) is out of the question. It is better to go with a tape player head? That is going to be tough to find, is there effective alternatives (that wont sound horrible)?

 

[audioguru]

It would be very difficult to position and align a tape recorder head. Since there will be no tape then I don't know how much equalization your circuit will need.

Olly K said that it was certainly not hi-fi so maybe is sounds awful.

 

[TheNewGuy]

I've gutted a tape allready for this project, I hope I won't regret it.

I'll try to look for a tape head, and maby you guys know of other ideas.


BTW it doesn't have to be HD but not all static either...

 

[audioguru]

Do you want the CD player to sound like an AM radio? Or worse?

 

[tcmtech]

The last time I worked on aligning a tape head was probably 15 years ago and that had to be done inside the unit while the tape was playing! And thats still having to hit a few thousandths of an inch tolerances to get it to sound right.

I really have my doubts as to you getting anywhere close to the accurate plus being you also have to align it to the other one front to back as well with in a few thousands of an inch for it to work right.

If you have ever seen a tape head there are two small dark spots on the surface that are about the size of pin heads. Thats the two points you have to line up with the other two pin head sized points on the receiver head for this to work at all.

Just spend the $15 and buy one. Or go around to garage sales and look for them. You could probably find one for $1.

 

[Sceadwian]

If you want decent quality it would be better to simply open the radio up and insert your signal after the tape head pre-amp circuit. before the power amplfiier.

 

[tcmtech]

For the time, effort, and money he will have and has already put into getting this to possibly work poorly just to save a few dollars he could come over to my place and cut and haul fire wood for me for a day and I would give him a good used Sony CD player head unit, speakers, and some cash to boot in return when he was done!

Plus the exercise and learning experience as to what time and money are worth could be good for him!

 

[Sceadwian]

Too bad I don't live closer to you tcm, I could use the exercise =)

 

[TheNewGuy]

...just buy it...

So I am over my head on this one...

I thought it would be a good learning experience. I guess this is one of those things that it is better just to buy it.

Allright, good thing you guys are here to keep me down to earth.

-TheNewGuy

PS-Maby I should just focus on tinkering with these stepper motors I have...

 

[kchriste]

Not to send you off on another tangent, but it would be easier to make a mono FM radio transmitter to feed your ipod audio into the car stereo via the FM tuner. AudioGuru has a nice frequency compensated circuit for this. Again, you can buy one pretty cheap,which doesn't drift, is FCC approved and encodes stereo too.

 

[TheNewGuy]

Not to send you off on another tangent, but it would be easier to make a mono FM radio transmitter to feed your ipod audio into the car stereo via the FM tuner. AudioGuru has a nice frequency compensated circuit for this. Again, you can buy one pretty cheap,which doesn't drift, is FCC approved and encodes stereo too.

Don't worry, all ideas are appreciated!

That sounds awesome, is this the one?

 

[kchriste]

That's the one. You'd have to attenuate the input signal because a portable MP3 or CD player puts out way more voltage than a microphone. Keeping the antenna short would be a good idea also; you don't want to be your city's radio station either!
Further on in the thread he mentions an IC which would give you stereo and is crystal controlled so the frequency doesn't drift. The IC may be hard to find though.

 

[audioguru]

Rohm make a bunch of very good crystal controlled FM stereo transmitter ICs that are used in all the good MP3 to car radio FM transmitters. The ICs should be available everywhere and Silicon Chip magazine in Australia has a project and a kit in Australia is available.