Connecting Bluetooth to Old Radio-CD: Eliminate Buzzing Sound from 1702 Connector Conversion

Dear Forum Members,
Welcome to the forum as a writer
what life forced me to do Because as the Bluetooth whistle works well in the car through the AUX input, I decided to convert the old boombox into a bluetooth speaker with a radio for holiday trips. As the radio does not have an AUX output, I connected the blutooth to the 1702 connector (I attach the diagrams), i.e. instead of playing discs that no one is wearing anyway ... I plan how everything will play nicely inserting the switch, but after folding the system, I hear a buzzing sound from a modem , sometimes the music will drown out but I like to listen to something quite quietly sometimes ...
Could one of the forum members bend over the schemes and say how to eliminate it?
Thanks in advance
Iwo

On this page you have the description of connecting the AUX input to the signal instead of the CD drive, there are capacitors in the line in there, read maybe it will help

Finally, someone who thinks soberly and doesn't want to build a 2x30W Bluetooth speaker from scratch (a lot of such topics lately). An idea worth praising because I myself advised several such solutions on the forum. I would wonder if it would not be better. It is easier to use the cassette input to plug into the pins of the head and use a jack with a switch, which will be responsible for turning on the reading from the cassette head after inserting the jack 3.5 plug into the socket. I gather myself for such a solution. Can I ask you what you want to fund it for?

E8600 wrote:

use the cassette input to plug into the head's pins

What about the pre-amp correction of the tape recorder?

398216 Usunięty wrote:

What about the pre-amp correction of the tape recorder?

I understand that it's about noise reduction etc? I didn't think about it but when the cassette adapter works, this should be the solution. I am not very advanced so if I'm wrong please correct it. The reading in the CD drive is not a digital case and the bluetooth adapter gives an analog signal.

E8600 wrote:

I understand that it's about noise reduction etc?

No. The point is that the signal from the cassette head is not a signal with a linear characteristic of the frequency. To compensate, the head is connected to the input of a correction amplifier, which reduces this unevenness. So if you connect the line signal (from BT) directly to the input of the cassette preamplifier once: You would have much too high sensitivity (because the signal from the head is millivolts, and the output from BT / and other line sources / is hundreds of millivolts), and two: heavily conquered (at the expense of the lack of high frequencies) the bass.
https://www.infomusic.pl/poradnik/38765,rejes...asmy-i-magnetofonow-wielosladowych-cz-i#Link5