Pre-amplifier Board Kits

[klem1]

Hello,

i am a new here and looking for some help.

I bought Amplifier Passive Tone Board to control volume, bass and treble on my hobby project: Amplifier Passive Tone Board Bass Treble Volume Control Pre-amplifier Board Kits | eBay

I connect it with TDA7377 amplifier and was dissapointed as volume was reduced for half if i compare to connection without mention Passive tone board.

What is reason? Can I improve volume?
I use 12V DC (2A) power supply.

Thanks and rgds

 

[ICG]

Well, you can't do anything with the board. It is passive, that means it cannot create any gain. To be able to get any + in the bass or treble, it has to generally lose it before. That is the principle of a passive tone control.

You could compensate for it with more gain in the amp, modify the input stage or with a higher input level. Or a active preamp.

 

[Bone]

Also the pots on this board should be A - audio taper not B - linear taper to work properly.

 

[ICG]

Also the pots on this board should be A - audio taper not B - linear taper to work properly.

The type char or number is not standardized, so it actually can be log. And to add to the confusion, type 'A' was linear back in the day.

 

[Bone]

I actually bought one of these boards and the pots are indeed Linear not Log.

 

[ICG]

I just wanted to note that these markings are not always meaningful. But if that's really the case, it is indeed a major fault which makes the board (IMO) completely unusable. Maybe some parts are salvageable.

 

[ecclesand]

I just finished building mine...removed the volume pot as I don't need it (this is going into a J2 clone preamp I built). Sounds pretty good.