Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Madison on February 19, 2013, 10:59:57 pm
-
I am using the bypass cap on the first gain stage as a boost (disconnecting the ground).
I have a 56k resistor strapped across it to ground hoping that would get rid of the pop.
But no dice.
I already have a good DC power supply off an additional 6.3 VAC for a LED boost indicator.
Would this be a good candidate for a relay?
Since this will be my first experience with a relay, can I get some pointers on how to do it?
-
I have always used a 1Meg resistor across the switches in my amps to good effect - no pops - although my switches were on the face plate (unused bright switches on a Super Reverb). Don't know if the resistor value is that critical.
Since you already have a DC supply built that's the hard part of the relay thing to me. I found Doug's relay info: http://www.el34world.com/projects/relay_switch.htm (http://www.el34world.com/projects/relay_switch.htm) to be really helpful on my recent relay activated mod. Those little relay boards and sockets are really slick. Per sluckey's advice I added a dropping resistor in series with my relay coil to bring the DC voltage across the relay to approximately 5VDC (my supply was about 6.9VDC IIRC). Really easy to implement. I use the relay to short out/bypass a pot. Since you are making and breaking a connection I'm wondering if a relay won't behave in the same fashion as your current setup.
-
http://www.el34world.com/Forum/index.php?topic=14348.0 (http://www.el34world.com/Forum/index.php?topic=14348.0)
Did you look in ARCHIVES?
with respect, Tubenit
-
>>Since you are making and breaking a connection I'm wondering if a relay won't behave in the same fashion as your current setup.
My question too.
I guess I'll find out.
Thanks.
>>Did you look in ARCHIVES?
Didn't see that.
Will have a read.
Cheers
-
If it pops with a switch it will pop with a relay. No difference in the contacts. Only difference is how the contacts are actuated.
-
Use a 5meg or 10 meg resistor to ground to stop popping.
-
On a cathode bypass cap, the resistor goes on the *switch*, not the cap.
-
Yeah, I think what you want is the resistor in series with the cap. The switch shorts that resistor. So open you have the cap and resistor in series, closed the cap is directly connected to ground.
(cathode)_____+cap-_____resistor______ground
|____/ ______|
(switch)
Is that how you have it now?
A relay isn't any different than a switch. A relay is just a switch that you flip with an electromagnet instead of your finger.
So you're flipping a switch, to turn on an electromagnet, to flip another switch...Relay.(like a relay race)
But if you are only grounding one thing there is no real reason to use a relay. That's just using two switches to do the job of one.
The main reason to use a relay is you only have to ground one wire to flip one or more DPDT switches.
-
Wired wrong.
Have the 56 between the cap and ground :BangHead:
Oops......too many wires in this amp.
Corrections to be made......report @ 11.
-
This is how I would wire it.
** Edited the pic. sluckey is right. I was only on my first cup of coffee.
-
This is how I would wire it.
Are you sure? Your switch will short the cathode resistor which will kill the tube bias.
-
Ok back to this finally.
I tried everything.
The panel switch is decent as far as popping goes but I just can't get the pedal to stop popping.
Darn shame.
So, I was messing around with this idea.
A NFB boost.
No popping.
It sort of works like a treble boost.Sounds pretty good.
But um, I just fried the cap.(bang! Woke me up pretty good!)
Any ideas how to improve this idea?
Thanks.