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To add a choke in driver stage B+ to smoothen the sound

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Posted on January 3, 2017 at 08:52:28
Eric Chan
Audiophile

Posts: 88
Joined: October 31, 2001
I have observed a situation
When I listen to my BAT VK75SE in evening time, a bit grainy sound
When I listen to it after 23:00, no more grainy sound, the vk75se use toroid power tranny, probably AC line picking up noise.

Can I add a choke in 1st VAS as to smooth out the sound?

 

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RE: To add a choke in driver stage B+ to smoothen the sound, posted on January 3, 2017 at 09:00:37
gusser
Audiophile

Posts: 2406
Location: So. California
Joined: September 6, 2006
Why not try an external AC filter box before modifying the unit?

 

RE: To add a choke in driver stage B+ to smoothen the sound, posted on January 3, 2017 at 10:55:36
megasat16
Audiophile

Posts: 207
Location: SoCal
Joined: April 15, 2015
+1 to guesser post! There is nothing to add inside the amp if it is an AC line noise. A isolation transformer or a common mode choke between the line and the amp may help clean the AC line noise a bit.

But it's probably not as good as a full featured AC line conditioner from PS audio, Accuphase or any other well known manufacturers.
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.Thou shall not stand where I type for I carry a bottle of Certified Audiophile Air and a Pure Silver Whip.

 

RE: To add a choke in driver stage B+ to smoothen the sound, posted on January 3, 2017 at 14:07:05
Eric Chan
Audiophile

Posts: 88
Joined: October 31, 2001
Hi, The VK75se itself also has the boost on lower treble region in which its midband always sounds glare too. I am wondering what I can do to make the lower treble less "attack" too. Not sure if adding a choke to the B+ supply to 1st stage 6h30 would slove this issue. It seems 6h30 is famous for treble overkilled

 

Voltage?, posted on January 9, 2017 at 07:24:33
FlaCharlie
Audiophile

Posts: 785
Location: Gville, FL
Joined: June 1, 2003
You may not have any unusual problem with line noise at all. Check out the thread above about how differences in wall voltage affects the sound.

While it may affect different amps differently, it's a fact that voltages vary quite a bit and that operating points will change as a result. This would affect any amp, vintage or modern, unless it has some sort of voltage regulator or something.

 

RE: To add a choke in driver stage B+ to smoothen the sound, posted on January 10, 2017 at 13:52:51
hifipaul
Audiophile

Posts: 681
Location: NY
Joined: December 22, 2008

Tube choices are always important. Find NOS equivalents.

 

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