2. amps-preamps
  3. 148712-122106

Power on popping sound

Hi Everyone!

Why does the left speaker always make a "pop" noise when the amp powers up?  Also, after preamp and amp are powered up there is a low buzz coming from the left speaker.  Not sure if I can hear the buzz from the right speaker.

The left speaker also makes a "whoosh" sound when powering off the amp.  

Getting paranoid about speaker damage.

Gear:
Speakers:                    Ologe 5 (Same thing happens with my LS 50 passives)
Amp:                            Forte Audio 1A 
Temporary preamp:     ADA Suite 8x8 - (I might pick up an Audible Illusion Modulus 2B but am open to suggestions.)
I also swapped in my Fostex HP A8 as a preamp and got the same popping and buzzing.
Rocket 88 speaker cables

Thanks!





hleeid
yogiboy's avatar
yogiboy
5,732 posts
 
Reverse the speaker cable going to the speakers. If the problem goes to the right speaker then you will know that left channel of the amp is the problem!
kalali's avatar
kalali
1,977 posts
 
Assuming the problem is isolated to the amp which will most likely be the case, try turning on the preamp a few seconds before the amp and see if you still hear the pop. You probably will not. As for the whoosh sound, its most likely the power supply capacitors that are near their end of life. My very old Adcom 545 did it too.
tomcarr
1,536 posts
 
In addition to the excellent advice from the above posters, always remember LOFO (amp is last on, first off). Turn-on sequence should always be: source(s), pre-amp, amp. Turn-off sequence should always be amp, pre-amp, source(s).

Tom
hleeid OP
219 posts
 
Thanks for your help! I will try reversing the cables and also the LOFO steps.

Is the power supply capacitor an expensive thing to replace?
tls49's avatar
tls49
1,351 posts
 
The Forte Audio 1A is a great amp, however it does have some age and should be serviced. The absolute best person for the job is Jon Soderberg at http://www.vintageamprepair.net  After his service, it will likely perform and sound better than it did when new. He was a service manager at Threshold when the amp was introduced for sale. 

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