blaupunkt: 22150; Paris

Hello all,  I have a problem with too much bass on this set. I have checked all the capacitors and resistors in the feedback and tone circuits, and all are OK.  If I disconnect the feedback to the volume control from the speaker output, the sound gets better with an increase in treble also.  Does anyone have any idea what's wrong?  Gary in Montreal.

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hello john, can i ask u , are u getting what is commonly reffered to as motor boating , this affect can be experienced by too high a voltage being fed into the valve s  from the mains transformer ,u could check the tappings on the transformer too see could u reduce the voltage , and check ur local mains electric voltage as well ,,just a thought!  best of luck with it john , regards maitiu.

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Hi Maitiu, no, it's not motorboating. Just too much bass that causes the speaker to rattle. I tried it on a large cabinet speaker and it's the same.

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Hello John,

Have you inspectet the currents in the Powerstage? You can make that if you measure the voltage
on pin 3 from EL84 (5,9 and 6,5 Volts) are recommendet.

Also test C 719 for insolation.

If that allright, i think, your observation is than not a fault.

The sound from the sixties does not match to today's programms any more.

If you want, Its give two possibilities there:

change R 810 of 12 Kohm to 8.2 or 6.8Kohm, or changing C811 from 0.01mF to 0.015 or 0.022 mF.

Maybe its better to make a combination of booth, e.g. 8,2 Kohms and 0,015 mF.

regards Hans

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Hi Hans,
   
       I think you were right about the sound not matching current broadcasting standards. The output tube current was fine, so I changed the values you suggested and now it sounds much better. Also in North America, the de-emphasis is different on FM than in Europe (but this set was made for USA, I believe).

    Thanks very much for your help,  John.

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Hello John,

 

if you want, see here there more information about SOUND in USA

 american_vs_european_fm_de_emphasis.html

If you have anny questions to this, tell mee.

 

regards hans

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