Need help diagnosing speaker thump

[Kw6]

Send it back if its under warranty and you aren't happy.




You said "soft pop". Is it louder than the whacks in the loudest drum solo you ever played? Does it make somebody in another room run in and say "WHAT THE HELL WAS THAT?!?!"




I'd get a second opinion here, first.

@restorer-john @solderdude

When you say send it back you mean get a refund? They won't give another unit they will fix it under warranty?

When I listen this weekend I will post again. As when I am testing for pop amp is on only for 30 mins vs 6 hrs

 

[Kw6]

I would get a faulty capacitor and or a capacitors soldering joint is loose, causing DC voltage leakage.

Dealer did say could be the capacitors or resistors in the power supply that is responsible for say stopping the voltage spike at power down.

 

[Kw6]

If it sounds good to you, don't worry about the pop. It's old, imperfect, hand built technology.

I talk to other Cayin owners and one dealer in Texas and they don't have pop at turn off. So my mind could be defective!

 

[solderdude]

Do other owners also report the same issue ?
When after biassing both channels do the same then it is unlikely there is a fault.
The reasoning is: first you had it in one channel only and moved along with the tube.
After adjusting both show this effect.
When there was something wrong it would have to be a common factor that would not be bias dependent.

Find out if more people report this (take speaker efficiency into account when the 'plop' is soft)

 

[Kw6]

Do other owners also report the same issue ?
When after biassing both channels do the same then it is unlikely there is a fault.
The reasoning is: first you had it in one channel only and moved along with the tube.
After adjusting both show this effect.
When there was something wrong it would have to be a common factor that would not be bias dependent.

Find out if more people report this (take speaker efficiency into account when the 'plop' is soft)

No other owners don't and one guy has same efficiency as my speaker 96 db.

I am not sure if it was only pop on left now. I only assume this as when i finish listening I am always closer to the left speaker. Maybe pop was from both speakers all along.

I am getting new 300b tube to test before getting it repaired. Big hassle to send it back.

 

[dfuller]

When you remove the DC voltage from the transformer, the collapsing magnetic field generates a transient spike that technically counts as AC - so the transformer passes it. That's all that's happening. Not to worry, it won't hurt anything.

 

[Kw6]

When you remove the DC voltage from the transformer, the collapsing magnetic field generates a transient spike that technically counts as AC - so the transformer passes it. That's all that's happening. Not to worry, it won't hurt anything.

Ok thanks! And no worries that some capacitors or resistors will fail say after my one yr warranty? If other people's amps did the same I feel better. It's a bummer mine slipped through the cracks.

 

[dfuller]

Ok thanks! And no worries that some capacitors or resistors will fail say after my one yr warranty? If other people's amps did the same I feel better. It's a bummer mine slipped through the cracks.

They likely will, eventually - electrolytic caps don't last forever and sometimes tube failure can burn resistors. But I wouldn't worry about it for now.

My knowledge on this comes not from hi-fi but from guitar amps, which are really the same idea.

 

[Kw6]

Ok thanks! It will probably happen after warranty expires and I send it to tube tech to change out! Fingers crossed

 

[yodog]

Keep us posted if you ultimately find the solution that works for you

 

[Kw6]

Keep us posted if you ultimately find the solution that works for you

Will do! Thanks for all your help! Trying new tubes in it soon. Doubt that will help but worth a try since i was going to change them out anyways.

 

[Kw6]

I feel confident issue resolved. Thanks to all who help offer me some suggestions!

This is reason for thump/pop

"As we informed you in your A-300BMK2 there is no problem. Soft pop sound should be the action of Relay.

NFB Switch is controlled by Relay. Under the state of -3dB the relay is Open and when you switched off the amplifier it has an action of Close for which it will have a pop sound while as for 0dB the relay is closed and therefore when you switched off there is no such sound.

Please kindly note. If you do not want to hear such pop sound please switch to 0dB first and then switch off."

 

[Balle Clorin]

I have the same amp . Is is beitifil and technically of the the best measuring300b and ssounding 300n amps. I put ind Emission Labs 300b and reissue Tung sol 6SN7 for lowest possible distortion and more than perfect WETriode Characteristic

 

[Balle Clorin]

Mobile phone spelling sorry