Wiring up to tape head circuit.

Scouse Monkey · 12-09-2004, 07:09 PM

This is a bit of a dodgy idea but i was wondering if anyone with experience with the internals of a car radio would know....

As i have just been beaten again on ebay for the amp I want - arghhhhhh - i was thinking about just temorarily using my old head unit stuffed into the depths of my dash and i wondered if would be possible to open up my radio and solder an audio lead onto the tape head circuit. My understanding is that there is a little amplification circuit after the tape head and i was thinking that if i located this i could then add my cables in at this point as the power output from my soudcard would probably be too much to simply replace the tape head with a connection. I would then cut the wire to the tape motor (a job i am going to do very soon as the rattle from the tape adapter is annoying me) and stick a tape in to enable the tape circuit - or i might just locate the tape selector switch and put a switch up fron to i can turn the radio on and off (and change station with my remote)

Is this idea nuts?

Andy

Cris · 12-09-2004, 07:15 PM

It defenetly doable, but I'd advise not to. I did that once, and the sound was, terrible. However, there are some special kind of tapes out there, that have a wire comming out of them, thus giving you an aux input. I have one of those tapes, and the sound was much better through it, than directly though the head of the casste.

toadster123 · 12-09-2004, 07:32 PM

hmm, thats interesting... i havent soldered on leads directily to the amp /circuit board.. but wouldn't u think that the sound would be better???

Either way, i have used those tapes that have a cable with a 1/8" head phone plug comming out.. and they do would pretty good (depending on the quality of the actual adapter [ i have two differnt ones, and one is really really bad... while the other is pretty darn good])

Scouse Monkey · 12-09-2004, 07:32 PM

Hi Cris, i am using one of those tape adapters now - basically just a tape head wired as a slave i guess. The sound is suprisingly good from it using my laptop but i jsut thought that that the whole signal-->coil-->coil--->signal-->amp-->stereo was a bit messy. I am tempted to completely canabalise my stereo and mount the display and some vital buttons in the little coin tray between my door and sterring wheel so i can use the car radio until something better that my dlink comes out.

So you wired up to the tape head? did you remove the tape head? I can imagine leaving it in would cause problems and i was thinking that the little tape head amplication circuit would cause problems with the gain being too high.

Cris · 12-09-2004, 07:44 PM

Well, to tell you the truth, I tried to do that with an old portable tape player, and modify it so I eventuallt would get a carkit out of it. It was a few years ago, so I don't remember very clearlly. Yes I removed the head, and I just hooked up the two wires. I then tried to plug another player though the auxiliary input created, adn the sound was terrible, although through the phone was quite good. Anyway, as I said, it was a long time ago... I also had experiences with the casste adapters. At first I had a cheap, no name one. The sound was crap. So, in a moment of pure maddness I bought another one. This time I paid a little more, like 18E more, so a total of 20E. It's a Vivanco, and the sound reproduced, is just like the one of a high quality original cassete.
BTW, I hope you don't mind I answered first this time too...

Scouse Monkey · 12-09-2004, 07:52 PM

I was counting on you answering! You are my personal car audio guru! I will be running all my speaker install past you when i get round to it!!! I have a branded cassette adapter which is pretty good but it just isnt loud enough with my MD player but i was suprised when i used my laptop which for some reason sounded much better when i switched to WinXP and MP10 compared to Win2K and MP9.Guess it is the drivers and stuff. Need to take my radio apart to diconnect the motor wires so i will have a look and see if i can bypass the tape head circuit as well as the head. Can't hurt to try and at least i now know it should work to a certain degree.

Cris · 12-09-2004, 08:27 PM

Quote: Originally Posted by Scouse Monkey

I was counting on you answering! You are my personal car audio guru! I will be running all my speaker install past you when i get round to it!!! I have a branded cassette adapter which is pretty good but it just isnt loud enough with my MD player but i was suprised when i used my laptop which for some reason sounded much better when i switched to WinXP and MP10 compared to Win2K and MP9.Guess it is the drivers and stuff. Need to take my radio apart to diconnect the motor wires so i will have a look and see if i can bypass the tape head circuit as well as the head. Can't hurt to try and at least i now know it should work to a certain degree.

Thank you, thank you very much...

I'll try and help as much as I can.
Same thing here, when I plugged a laptop into the cassete adapter, in XP it sound pretty loud. Louder than a normal cassete anyway...Wierd.
Well, I guess you know what they say...you'll never know, unless you've tried it.

Tred · 12-09-2004, 08:33 PM

if your looking to hook up the line out directly to the tape unit, try looking on the back of the HU for something the says "tape". Then u can cut the leads to the tape and solder on your own leads. This way you get direct input of sound and you dont have to deal with a wire coming out of your dash. If you end up going this route you will still need to have a Tape adapter in the bay. That is the only way i know how to activate the new aux line you made. I think the tape reader had sensors to make sure the tape is running properly, if it is not spinning it might spit the tape out or mute the new aux line. This is probably a safety feature if a normal tape got jammed. I hear SONY adapters are pretty silent if you decide to do this.

Scouse Monkey · 12-09-2004, 08:59 PM

Tred you lost me with the bit about lookin on the back for the "tape" thing. My head unit is a standard pug clarion one with no CD input (i was going to get a cd changer for it but when i found out i couldnt i got thinking and stumbled accross this site!!!). I am guessing that there is a switch pressed when you slide the tape in (manual eject so no way for it to spit tapes out) that activates the tape circuit and the motors and i doubt they spent money on something to detect tape jams - more likely that there is a slipper on the drive gear to cope with tape jams - or it just snaps the tape! I have only ever worked on the internals of VCRs which must be pretty similar and i used to press the microswitches to fool them into thinking there was a tape there for testing so i suspect it is similar (except VCRs do as you say and eject jammed/tight tapes but they have powered ejects).

mp3hombre · 12-10-2004, 12:50 PM

Hi Scouse Monkey.
I did exactly that and it worked OK. The sound wasn't that good because of the head amp circuit but after I tweaked it a little bit it was OK. It's better to connect the wires AFTER the heads amplifier chip. There's also a "tape in" switch that you have to take into account when doing this mod.
Good luck!!

Scouse Monkey · 12-10-2004, 12:59 PM

Cheers buddy, that is very encouraging. might go and rip my stereo out again to see how easy it is to find the amp circuit in order to bypass it. Also need to measure my dash as i am begining to think making my own motorized LCD might be a safer option than modding my dash.

Matthew230 · 12-10-2004, 01:26 PM

You'll never get a good sound from that because a tape head picks up magnetic pulses from the magentic tape and then sends them down a wire. This kind of signal differs from the type you'll get out of your line out from the PC, which is a much more fluid and fuller signal.

Imagine, if you will, two pipes carrying water, the pipe representing the tape gets spurts of water as a someone chucks buckets of water down it. The pipe representing your PC is fed directly from a mains hose allowing for your pipe to be constantly filled. Now with the two pipes you still have the same collection method at the other end, imagine someone is fuilling up buckets and moving them along. Works fine for the tape, but for the PC you will get overspilt water whilst the buckets are moving. (Had enough of analogies ?!?)

So your music will sound compressed and hollow.

Get a tape adapter whilst you wait for an amp.

mp3hombre · 12-11-2004, 08:56 PM

Let's see, what's in a tape adapter? A 1/8 stereo plug, wires and a stereo tape head.
(I built one loooong ago, before they were so common). The sound is then coupled magnetically from this head to the head in the car's tape assembly. Then, the sound is processed ("equalized", usually with a capacitor and a resistor network) and amplified using an IC. After, the sound is just a "regular" sound going to an audio switch. It's at this point where an AUX input is fed in in H/U that come with such an input.
The idea for this mod is to avoid all this coupling and processing and feed the audio from the pc to the audio switch. It takes some tweaking but it can be done.

Scouse Monkey · 12-12-2004, 05:31 PM

Also in a tape adapter are 4 very important resistors! well in mine there is anyway, I have my clarion head unit in bits on my desk! the is a little circuit board attached to the tape head but it doesnt seem to do much before outputting the 3 wire for the audio to the head unit so it just seems to be a osme kind of bridge for the two sides of the tape head. There is also a mysterious green wire but i ahve no idea what that is - maybe an earth - dunno. Nice little soundcard pcb type connector tot he head unit so worth a crack anyway. If not i will get an el-cheapo head unit off ebay with CD in and mod that.

xtra · 12-15-2004, 02:36 AM

I hacked a tape HU to take aux in last month. it's a 96 altima hu which i believe is a clarion branded. acutally it's giving me a pretty good sound, much better than tape and radio.

open the head unit and look for "left out " and "right out " on the PCB

Good Luck

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