Macintosh 2100 power thump issue

[ThachNguyen]

Dear all,

-I have an issued with MC 2100 I have just bought. Overall, this power works perfectly and sound is amazing even it was produced in 1967 as my testify this power 100% origin(transformers, driver transistor, power transistor, circuit board....) all still original, it's clean sound too(a little hum but very minor and acceptable because it was produced in 1967-older than my age!).

- My problem now is when I connect MC 2100 with my Pre-amp C28 everytime I turn off the power, because MC 2100 designed without power button on/off, so I must turn off by on/off button on power strip then the sound is "Thump" on both speakers if the volume in C28 gain up the sound is louder if I turn the volume in C28 to zero(not off) the sound still hear but quieter.

-My question what is problem with my Mc 2100? And How I can fix it? Do you think it will damage my tweeter or woofer?

- I am highly appreciate your advice!

 

[ThachNguyen]

Any one can help? Thank you!

 

[MACKIE1975]

Add this to the end of the power amp cord then turn it ON last and turn if OFF first

 

[dr*audio]

If you do not connect the preamp, do you still get the thump? If not, the problem is in the preamp.

 

[ThachNguyen]

If you do not connect the preamp, do you still get the thump? If not, the problem is in the preamp.

Hi,

Yes, you are right if I do not connect with preamp there is no Thump. Now I got the problem already may be the preamp issue not power 2100. Thank you so much!