I have home built a Orange Tiny Terror. I have not blown any fuses.
However, when I powered it up, and go off stand by, I get a hum. I was playing an MP3 player through it. I could hear it faintly but not that loud.
Help is there anything I can look for to fix this problem. I have a feeling it is something simple
below is a link for the schematic I used.
Help with hum problem on homebuilt Tiny Terror
Moderators: pompeiisneaks, Colossal
Help with hum problem on homebuilt Tiny Terror
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Re: Help with hum problem on homebuilt Tiny Terror
I don't know this amp but it seems designed for MI input. Does it work with a guitar plugged in?
Re: Help with hum problem on homebuilt Tiny Terror
Make sure all the connections are ok. This amp should be quite loud.
Re hum -- is it 50Hz (60Hz)? Or 100Hz (120Hz for US)? There are various reasons in each situation. Many times it's just a ground loop (if the hum has a fundamental frequency of 50/60Hz). This kind of hum can also be introduced by filaments; this can be alleviated by either referencing the filament supply to ground by using two resistors, or referencing it to a positive voltage of 10-30V.
If it is 100/120Hz -- it can be caused by insufficient B+ filtering; obvious solution -- increase the size of the filter caps.
Two -- you have a lot of cables in there... And these are quite long... Use a shielded cable for signal (only one side grounded). Also, don't forget to solder anti-parasitic resistors straight to a tube's socket -- this helps to tame high-frequency oscillations (most of the time inaudible).
Re hum -- is it 50Hz (60Hz)? Or 100Hz (120Hz for US)? There are various reasons in each situation. Many times it's just a ground loop (if the hum has a fundamental frequency of 50/60Hz). This kind of hum can also be introduced by filaments; this can be alleviated by either referencing the filament supply to ground by using two resistors, or referencing it to a positive voltage of 10-30V.
If it is 100/120Hz -- it can be caused by insufficient B+ filtering; obvious solution -- increase the size of the filter caps.
Two -- you have a lot of cables in there... And these are quite long... Use a shielded cable for signal (only one side grounded). Also, don't forget to solder anti-parasitic resistors straight to a tube's socket -- this helps to tame high-frequency oscillations (most of the time inaudible).
Cheers,
-Tomek Drabas
___________
‎"One should not pursue goals that are easily achieved. One must develop an instinct for what one can just barely achieve through one's greatest efforts."
—Albert Einstein
-Tomek Drabas
___________
‎"One should not pursue goals that are easily achieved. One must develop an instinct for what one can just barely achieve through one's greatest efforts."
—Albert Einstein
Re: Help with hum problem on homebuilt Tiny Terror
I find it strange that you mounted the component board upside down.
What was the reason for this?
Also, did this amp ever work properly or was it bad from the start?
What was the reason for this?
Also, did this amp ever work properly or was it bad from the start?
Tom
Don't let that smoke out!
Don't let that smoke out!
Re: Help with hum problem on homebuilt Tiny Terror
Do any of the Volume, Gain or Tone controls influence the hum?
Listen carefully as you flip the Standby from Play to Standby mode. Does the hum go away immediately, or does it fade out over a period of a couple of seconds? If it fades out, it's usually a problem with heater wiring or possibly a bad tube. It sounds like a low organ note. If it cuts off immediately it's usually a problem with the grounds and sounds like more of a buzz. The ground side of the bridge rectifier should go the ground side of the 100uF cap, not directly to the chassis. How are the rest of the filter caps grounded? Describe all the connections to ground.
Listen carefully as you flip the Standby from Play to Standby mode. Does the hum go away immediately, or does it fade out over a period of a couple of seconds? If it fades out, it's usually a problem with heater wiring or possibly a bad tube. It sounds like a low organ note. If it cuts off immediately it's usually a problem with the grounds and sounds like more of a buzz. The ground side of the bridge rectifier should go the ground side of the 100uF cap, not directly to the chassis. How are the rest of the filter caps grounded? Describe all the connections to ground.