130 Ohm 3w ceramic explanation
Moderators: zaphod_phil, Daviedawg, Graydon, CurtissRobin, colossal
- JMPGuitars
- Super Duper Admin
- Posts: 3968
- Joined: Tue 09/18/12 8:00 pm
- Location: South Central, MA
- Contact:
Re: 130 Ohm 3w ceramic explanation
5W or 10W doesn't matter.
The only thing that matters is that you bias correctly. You can use this calculator to determine that: https://robrobinette.com/Tube_Bias_Calculator.htm
You want to bias the tubes between 75 to 85%. Assuming a typical transformer, you probably need 180 ohms, but you can measure and determine that later.
The only thing that matters is that you bias correctly. You can use this calculator to determine that: https://robrobinette.com/Tube_Bias_Calculator.htm
You want to bias the tubes between 75 to 85%. Assuming a typical transformer, you probably need 180 ohms, but you can measure and determine that later.
1 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
- davemojo
- Occasional poster
- Posts: 161
- Joined: Wed 01/06/21 4:14 am
- Location: Hoofddorp
- Contact:
Re: 130 Ohm 3w ceramic explanation
Thanks Josh, I will check on that too.JMPGuitars wrote: ↑Sat 03/20/21 7:30 am5W or 10W doesn't matter.
The only thing that matters is that you bias correctly. You can use this calculator to determine that: https://robrobinette.com/Tube_Bias_Calculator.htm
You want to bias the tubes between 75 to 85%. Assuming a typical transformer, you probably need 180 ohms, but you can measure and determine that later.
So I bet that if the Stewmac build (Let's leave aside if is a crap building option ) but I would assume that if they made that build with in mind the consideration of correct Bias so it would mean that 130 Ohms 3W suggestion should be the correct Bias based on that build?
0 x
- JMPGuitars
- Super Duper Admin
- Posts: 3968
- Joined: Tue 09/18/12 8:00 pm
- Location: South Central, MA
- Contact:
Re: 130 Ohm 3w ceramic explanation
Nope. For one thing, most of the kits around are based on dated variables. For example, source AC was lower 40 years ago, but they still just copy the same components and values. Higher source AC = higher voltages in your circuit.davemojo wrote: ↑Sat 03/20/21 7:54 amThanks Josh, I will check on that too.
So I bet that if the Stewmac build (Let's leave aside if is a crap building option ) but I would assume that if they made that build with in mind the consideration of correct Bias so it would mean that 130 Ohms 3W suggestion should be the correct Bias based on that build?
Don't trust the kit, trust the math. Do the math and adjust the kit.
4 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
- zaphod_phil
- Builder, Admin
- Posts: 15208
- Joined: Wed 03/19/03 2:00 am
- Location: YYZ
Re: 130 Ohm 3w ceramic explanation
Hear, hear!!JMPGuitars wrote: ↑Sat 03/20/21 8:32 amFor one thing, most of the kits around are based on dated variables. For example, source AC was lower 40 years ago, but they still just copy the same components and values. Higher source AC = higher voltages in your circuit.
Don't trust the kit, trust the math. Do the math and adjust the kit.
2 x
Nature abhors a clean tube amp