Modification for Speaker

[nick_f]

Hi All,

My first attempt to test my Hammerhead ended up with some smoke coming from the audio pot. That happened when I got with the setting close to the maximum volume. I was using a small power pot, and a 8 ohm speaker. I am not sure I didn't have some errors in circuit, but I think I didn't.
I put a resistor in series with it (few tens of ohms), to avoid increasing the current through the pot too much. This way it was working ok, but a lot of the audio signal was dissipated by the pot + resistor.
For this reason, I decided to use an audio transformer to increase the impedance of the speaker. I used a small transformer that I purchased from Jaycar: 1K OHM CENTRE TAPPED - 8 OHM OUTPUT TRANSFORMER
I still have plenty of sound at maximum volume. Before I had some sort of a harsh sound coming from the speaker at higher volume, now it's better.
At present, I am using a 1kOhm log pot for the speaker, I will change to the 5kOhm pot when I will get one.

Regards,
Nicolae

[rajesh]

hh

Hi All,

My first attempt to test my Hammerhead ended up with some smoke coming from the audio pot. That happened when I got with the setting close to the maximum volume. I was using a small power pot, and a 8 ohm speaker. I am not sure I didn't have some errors in circuit, but I think I didn't.
I put a resistor in series with it (few tens of ohms), to avoid increasing the current through the pot too much. This way it was working ok, but a lot of the audio signal was dissipated by the pot + resistor.
For this reason, I decided to use an audio transformer to increase the impedance of the speaker. I used a small transformer that I purchased from Jaycar: 1K OHM CENTRE TAPPED - 8 OHM OUTPUT TRANSFORMER
I still have plenty of sound at maximum volume. Before I had some sort of a harsh sound coming from the speaker at higher volume, now it's better.
At present, I am using a 1kOhm log pot for the speaker, I will change to the 5kOhm pot when I will get one.

Regards,
Nicolae

hi nick what's your mean to log pot. i think you saying big size of pot. but if you reduce signal from r35 it give you good audio any way i used my nokia mobile audio ear card.

[nick_f]

HI Rajesh,

Log pot is short for logarithmic potentiometer. The adjustment of volume in audio equipment is done with logarithmic potentiometers, not the linear type. On a potentiometer you can usually find the marking A5kOhm or B5kOhm.

B means the potentiometer has a linear variation (at half the rotation, you have half the resistance).
A means the potentiometer has logarithmic variation (at half the rotation, you have about 17% of its total resistance).

Do some search on the internet about logarithmic potentiometers to find out more.

Regards,
Nicolae

[rajesh]

hh

HI Rajesh,

Log pot is short for logarithmic potentiometer. The adjustment of volume in audio equipment is done with logarithmic potentiometers, not the linear type. On a potentiometer you can usually find the marking A5kOhm or B5kOhm.

B means the potentiometer has a linear variation (at half the rotation, you have half the resistance).
A means the potentiometer has logarithmic variation (at half the rotation, you have about 17% of its total resistance).

Do some search on the internet about logarithmic potentiometers to find out more.

Regards,
Nicolae

hi nick i seen that good i will replace yet.thank's