2. amps-preamps
  3. 1080550955

why distortion and what is the cure

Hi , this is my 1st post so go easy pls!!
I have an old sugden a21 amp and a crap pair of celestion F2 f/standers - 87db / 8ohm. When i turn up the amp past about 1 oclock the sound just breaks up/distorts.This also happened with a MF b1 amp. Is it the speakers or the amps that are faulty? I am thinking of getting the A28 sugden as i like the sugden sound and if it is the speakers at fault can anyone suggest Fstanders to partner? (under $700 s/h pls )
gar1
joeabrams
132 posts
 
The answer would be easy if you were using a turntable: there is a point where the SPL in the room is causing the TT to go into feedback. The solution is to separate/isolate the TT from the speakers.
BUT, if you are using a CD as the source, then there are (too)many possible answers.
gar1 OP
7 posts
 
Thanks Joe
I am using CD as the source. The sound with both amps is fine at low volume but turn it up and yuck!! Have spoken to Sugden who suggest that A)one or two of the power transistors may have gone or B)the speakers arent sensitive enough for the amp. Amp is 12 watts class A and speakers are as above.I love the sound of the amp and really dont want to change it if i can help it.The speakers can go out with the trash. So cmon guys - solutions and speaker suggestions (pref F/S with waf)
edesilva
768 posts
 
I'm guessing its not a vibration issue, but simply overdriving your poor 12 W amp. You don't exactly have efficient speakers, so if you are trying to listen at high volumes (1 o'clock on my pre is deafening), your Sugden is probably running out of gas, distorting and clipping.
tjz
14 posts
 
I'd have to agree with Edesilva's last comment, it sounds as if you have hit the output limits of your system. Many systems are at or near peak output at the 1-2 o'clock positions. And tube sound typically goes downhill very fast once you hit peak output.
fatparrot
1,314 posts
 
I also agree with the under powered amp and clipping scenario. How old are these speakers? I couldn't even find this model listed in the Agon Bluebook. If they use '70's or early '80's drivers with foam surrounds (the outer edge of the speaker cones), you might check this material to see if it has deteriorated. I have seen foam surrounds actually turn to dust!

Tjz, I disagree regarding your statement about tube amps! Tube amps will gradually start to distort when overdriven (this can actually be beneficial, as guitar players use this method to generate a myriad of sounds and tones), while solid state amps usually start clipping almost immediately when overdriven...this is bad news for speakers!
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