Speakers clipping with no current drive on Technics amp running off a generator

[SammydesinasNL]

Hi All,

Having recently bought some new speakers to add to my amp to pass on to a friend there has been an issue in the new set-up. The speakers clip when the volume is turned to the 1 'o clock position. The amp is a technics SU-A900 and the speakers are Mission 780SE (with the wraparound grille). The amp is rated at 65wpc/8ohms and the speakers draw 25-75 at 6ohms so the power draw should be fine right? When the amp is turned on the current drive light does not switch on. The amp is also running of a generator which is not providing a clean sine wave as power. Any help or advice would be much appreciated.

[walpurgis]

I hope you are only using modest bass control boost (if any).

It could be that the amp is not drawing enough juice from the generator and distorting. Can't see why you'd need a generator if you're in London though.

[dowser]

I'd suggest it's related to generator - they cannot provide the same current delivery as the mains, and probably even has some sort of auto-sensing overload protection which maybe triggered by transient response requirements of the amp under heavy load. Easy to test - try plugging same setup into mains.

[struth]

If its a smallish generator then itcwill be the problem. Even larger ones are not recommended for such uses unless they are specially designed

[Reffc]

Hi All,

Having recently bought some new speakers to add to my amp to pass on to a friend there has been an issue in the new set-up. The speakers clip when the volume is turned to the 1 'o clock position. The amp is a technics SU-A900 and the speakers are Mission 780SE (with the wraparound grille). The amp is rated at 65wpc/8ohms and the speakers draw 25-75 at 6ohms so the power draw should be fine right? When the amp is turned on the current drive light does not switch on. The amp is also running of a generator which is not providing a clean sine wave as power. Any help or advice would be much appreciated.

Is this right or a typo? Did you mean that you have a 230V supply (ie re-generator) in which case, you need to check to current availability to see if it is correctly rated, BUT the 780 SE are not an especially power-hungry speaker. I used to drive them with a 25wpc amplifier and clipping was never an issue at moderate volumes, so i would suggest all is not well somewhere else in the system. I would avoid using the generator and plug the amp direct to the mains socket then re-try. If you hear distortion then it's likely a faulty amp or a speaker problem. Whatever you do, it is not recommended you continue with driving the speakers into clipping as you'll fry the tweeters.

[SammydesinasNL]

Thank you for all the responses. I did initially had it hooked up to mains with no issue and the clipping didn't develop until a few weeks after switching to the generator setup. As Reffc points out they aren't really power hungry so that shouldnt be an issue. Also wasn't sure if maybe switching to a less powerful amp would solve the problem as the current draw wouldn't be the same? A weaker amp would also still provide enough power to the speakers. I set up this system for a friend after he previously blew up his old bookshelfs with too much bass (I figured too large a power draw on a bassy song?) so focused on sensitive speakers with enough power pushing them.

Previous set-up was 25 wpc but I didn't figure a lower power draw would lead to a cleaner sine wave?