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VR tubes - loadspeaker pop

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Posted on June 27, 2012 at 15:23:41
vbenonisen
Audiophile

Posts: 56
Joined: November 20, 2010
 Hello!

Is there a simple solution to stop the loadspeaker from "popping" when the VR tubes in the power supply ignites in a single ended power amp?

Regards,
Vidar, Norway

 

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RE: VR tubes - loadspeaker pop, posted on June 27, 2012 at 16:30:58
Swanson
Audiophile

Posts: 109
Location: New Jersey
Joined: June 16, 2003
 Well,
Since nobody has replied to this post yet I will
give it a shot.In a properly designed piece of tube
gear the VR tubes should be ignited well before the
rest of the circuits are allowed to operate.Since we
do not have a schematic of your amp we will have to
guess at what is going on.If your output tube is directly
heated it is probably coming up to speed along with the input
tubes faster than the VR tube can strike and stabilize.Two possible
ways to solve this problem would be to use SS rectifiers in the
power supply to get the VR tubes up to speed right away or install
a muting circuit with a timer that shorts the output of the amp
untill everything stabilizes.It would help alot to post a schematic
of this amp so other people can see it and offer advice.
Regards,
Swanson

 

RE: VR tubes - loadspeaker pop, posted on June 27, 2012 at 16:40:16
Swanson
Audiophile

Posts: 109
Location: New Jersey
Joined: June 16, 2003
 Forgot to add that you might not have enough
current flowing through your VR tubes when they are unloaded.
Increasing the no load current will help the tubes strike
faster even with a tube rectifier so we need to know how
much current is flowing through those VR tubes.
Regards,
Swanson

 

RE: VR tubes - loadspeaker pop, posted on June 28, 2012 at 09:14:04
vbenonisen
Audiophile

Posts: 56
Joined: November 20, 2010
 First of all thank you for your answer.

I am sorry but I haven't as of yet written any schematic - but it is a very simple three stage single ended DHT dual mono amp with anode chokes and interstage transformers (1H4G-6W6-300B) and I´m using the VR tubes to set the voltage for the input stage.

You are of course correct (I should have thought of that) in pointing out the fact that the output tubes needs to be the last one to get powered up to avoid the "popping" in the loadspeakers.

A muting circuit sounds difficult to built so maybe I need to do some more work on the power supplies...

Regards,
V


 

RE: VR tubes - loadspeaker pop, posted on June 28, 2012 at 09:15:04
TimFox
Audiophile

Posts: 589
Location: Chicago
Joined: January 14, 2006
 In a normal VR-tube shunt regulator circuit, the current through the tube is higher when the load is disconnected, and when the load starts to draw current the current through the VR tube falls. The design goal is to keep both of those levels within the proper operating range (e.g., 5 to 30 mA) of the VR tube.

 

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