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Tremolo / Pulsing music from AMP


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I have a Vintage Sansui 7070.

During the quiet sections it is very obvious that the amp is producing a pronounced Tremelo or pulse through all the drivers.

I say 'amp' not speakers because it does it through the headphones as well.

I have changed cables, changed c.d players, and the tremelo/pulse remains.

I had a look inside and no caps are bulging or showing physical weakness, but I am guessing people are going to suggest it leaking caps.

My question is, has anybody had this as a symptom of bad caps before, usually I get crackling or popping or distortion from bad caps, never had tremeolo/pulse.

The amp is perfect quiet and performs well otherwise.

Thanks for your time.

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19 hours ago, The Hurting said:

 

I have a Vintage Sansui 7070.

During the quiet sections it is very obvious that the amp is producing a pronounced Tremelo or pulse through all the drivers.

I say 'amp' not speakers because it does it through the headphones as well.

I have changed cables, changed c.d players, and the tremelo/pulse remains.

I had a look inside and no caps are bulging or showing physical weakness, but I am guessing people are going to suggest it leaking caps.

My question is, has anybody had this as a symptom of bad caps before, usually I get crackling or popping or distortion from bad caps, never had tremeolo/pulse.

The amp is perfect quiet and performs well otherwise.

Thanks for your time.

 

 

Guessing it might be what we called motorboating.  That is,  a low frequency oscillation in the amp.  It is caused by inadequate power supply isolation between stages within the amp, and old capacitors are the main culprit in old amps.

Edited by aussievintage
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5 hours ago, aussievintage said:

 

 

Guessing it might be what we called motorboating.  That is,  a low frequency oscillation in the amp.  It is caused by inadequate power supply isolation between stages within the amp, and old capacitors are the main culprit in old amps.

Thank you so much for your reply.

It makes sense and that was my biggest concern. 

So I swapped out the Sansui with a newish yamaha thing I have, and it does the exact same pulsing / tremelo thing, exact same, and I have tried 3 different cd players, so it must be the speakers, but... I also hear the effect through headphones) so confused.

I went around the house and turned off everything but the fridge to make sure it wasn't something in the house.

I did replace the capacitors in the speakers myself recently, but just like values for like values.

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55 minutes ago, Neo said:

The headphones are plugged into the amplifier? Or a headphone amplifier?

Also define newish Yamaha?

Neo

 

Headphones plugged into amplifier

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  • 4 weeks later...

That's a curly one. I just put together a little vibro-champ guitar amp head and found  that the addition of a little curcuit with a 5751 made it suffer the very same consequence. 

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