[SpeakerBox]

   
It's not that loud and only happens when powering down. But it is audible.
But if I put the speaker selector to off or to one of the unused speaker outputs there is no thump.
Strange because the speaker protection relais have been renwed and DC offset calibrated like I posted above.

 
Skylab is right that any power on/off thump on the 1250 is bad.  I get no such issues on mine.  Usually the protection relay must be replaced (or the caps driving it).
 
If it stays engaged too long you will get a power off thump.

 

[Oregonian]

   
Skylab is right that any power on/off thump on the 1250 is bad.  I get no such issues on mine.  Usually the protection relay must be replaced (or the caps driving it).
 
If it stays engaged too long you will get a power off thump.

Agreed - having 8 vintage systems in use, NONE have a power on/off thump.  Something is not right with the 1250.  My 1050 is rock solid silent. 

 

[Mechans1]

I have no vintage system running right now except for a tube Fisher 400 receiver, which I have not hooked up to speakers in a while. I remember getting a subdued bump /thump from the Fisher.  I recall getting a thump from the  Kenwood KA- 7100 I used for over 20 years.    I tried to buy another KA-7100 for my son who wanted to have what I used as a Teenager.  I  was unable to buy one without serious issues.  I was astonished by sellers who say it's 'working' if a light turns on when the on switch is flipped.  This happened a few times and I gave up !   Yes I got my money back  but is was a pain I didn't need.
Do you vintage guys repair them yourselves or do you have access to techs that can work on them?

 

[AppleheadMay]

Weird, the speaker protection relays and all caps have been replaced though.
The thump sin't there when I switvh the speaker button off first like I usually do on all my amps.
And it isn't loud. Audible but not loud.

 

[SpeakerBox]

 
Do you vintage guys repair them yourselves or do you have access to techs that can work on them?

 
I repair my own - but am a Electrical Engineer so that does not hurt.

 

[Skylab]

Weird, the speaker protection relays and all caps have been replaced though.
The thump sin't there when I switvh the speaker button off first like I usually do on all my amps.
And it isn't loud. Audible but not loud.

Well of course the thump isn't there when you switch the speaker button off first...because then there are no speakers connected for you to hear the thump from!

DC offset can drift. If you have a multimeter, you should check this. If you don't have a multimeter, you should get one

 

[SpeakerBox]

DC offset can drift. If you have a multimeter, you should check this. If you don't have a multimeter, you should get one

 
That can especially be an issue if the adjustment pots were not replaced.  Old pots don't always hold their settings and will drift with heating and cooling.

 

[AppleheadMay]

Well of course the thump isn't there when you switch the speaker button off first...because then there are no speakers connected for you to hear the thump from!

DC offset can drift. If you have a multimeter, you should check this. If you don't have a multimeter, you should get one

 
I know, I know, and I knew the minute I posted it, I knew my statement was just as logical as it sounded stupid. 

 
Yes, I am the proud owner of a multimeter which I have used once. I have no idea how to use it anymore and even if you explained it to me I would be able to use it but that wouldn't fix the problem. 
So, Im going to my repair guy again and have them check those protector relays for free this time.

 

[AppleheadMay]

   
That can especially be an issue if the adjustment pots were not replaced.  Old pots don't always hold their settings and will drift with heating and cooling.

 
 
I posted it somehwhere befor but with the sheer number of pots replaced I think there isn't an old pot in the thing anymore. All tantalums and electrolityc ones have been replaced and I have a bag full of the old pots here.
He also did a DC-offst check. I posted it somewhere in this thread.

 

[PhoenixG]

   
 
I posted it somehwhere befor but with the sheer number of pots replaced I think there isn't an old pot in the thing anymore. All tantalums and electrolityc ones have been replaced and I have a bag full of the old pots here.
He also did a DC-offst check. I posted it somewhere in this thread.

I think you are mixing capacitors with potentiometers. Caps store charge and come in electrolytic flavors among others. Pots are variable resistors and are usually turned to be set. they can get small drift issues with extensive use or long periods with high heat. Small drift can lead to large changes in where things are set to inside.

 

[AppleheadMay]

  I think you are mixing capacitors with potentiometers. Caps store charge and come in electrolytic flavors among others. Pots are variable resistors and are usually turned to be set. they can get small drift issues with extensive use or long periods with high heat. Small drift can lead to large changes in where things are set to inside.

 
Indeed. I know the difference between a cap and a pot very well but 't was ealy in the mornin' here. Besides, a capacitor in my labgueage is called a condensator. Confuison all around. nevermind me ...

 

[SX3900]

+1 for no power on thump for both my SX-3900 & SX-3800 during on/off switching. But you do hear the delayed power relays kick-in. 

 

[Amish]

Well I doubt this amp fits here but it is vintage! Magnavox 8802 (running a set of Hsu speakers and powering my cans via HiFiMan - HE-Adapter)
 

 

[r2muchstuff]

I love it!  Where did you find such a lovely thing?
 
I have only seen such on a basic metal base or re boxed into wood frames.
 
r2

 

[Amish]

  I love it!  Where did you find such a lovely thing?
 
I have only seen such on a basic metal base or re boxed into wood frames.
 
r2

Thanks!
It still has the metal chassis but it has been painted white and the builder hand crafted a very nice wood base for it which he also painted white and blue. This unit was pulled out of a vintage Maggie console, rebuilt, upgraded to be standalone. The builder is a guy by the name of Dave Ricciardi. He's built and sold around a dozen or so amps so far.