hartke A70 noise when turn on/off

[Mr. BassmanPT]

just bought a hartke A70 from thomann website.

everytime i turn it on, it gives me a "BUMP" noise. it is hard to describe it.. maybe a bass drum is what it is like! yes, it sounds like a bass drum!

it does the same when i turn it off.

is my unit defective? never had one of these small hartke combos before.

[BassmanPaul]

Perfectly normal for a SS head. Most decent amps have a speaker delayed on/ instant off to prevent these thumps from reaching the speakers.

Paul

[Mr. BassmanPT]

Originally Posted by BassmanPaul

Perfectly normal for a SS head. Most decent amps have a speaker delayed on/ instant off to prevent these thumps from reaching the speakers.

Paul

never heard anything like it (the noise)! i have a hartke ha3500 and it does not has any of this noise (but that is in a different category). i also had a marshall solid state b65 that was silent.

i am really surprised with this. i thought the hartke a70 was a decent combo

[Mr. BassmanPT]

is there a way to attenuate this? i already tried to max out the limiter but without success.

[BassmanPaul]

It is caused by the output stage powering up and down. The size of the "thump" depends on how well balanced the chosen topology is. There is nothing you can do to alleviate this.

Paul

[Mr. BassmanPT]

ok, thank you once again for your answer.

never thought hartke would put something like this in the market.. it sounds good and it is built like a tank but damn this thing really shakes my bedroom door each time i press the power button!

[KramerBassFan]

Originally Posted by cmaranhao

ok, thank you once again for your answer.

never thought hartke would put something like this in the market.. it sounds good and it is built like a tank but damn this thing really shakes my bedroom door each time i press the power button!

Try turning the VOLUME knob all the way down when you turn it off.

And this isn't bad for it at all as BassManPaul Has Said.

My 1981 Sunn Coliseum Does this too, and so do some of my other Transistor amps.

Nothing to worry about.... and it isnt a design flaw either! I.E. it isnt going to blow your amp up.

[Mr. BassmanPT]

thanks, glad to know it will not damage anything. tried turning the volume down, it reduces the decibels of the noise a bit.