Look further down in the thread. This was corrected in the second schematic posted.Bob-I wrote:Wait... I see a problem. The B+ only comes from the choke side. Follow the current with the switch set to the resistor, the current will go through the resistor, then through the choke and finally to the B+, not good as you'll overload the choke.
You'll need a DPDT switch so that the B+ can be switched to either the choke side or the resistor side.
Robben Ford Switch?
Moderators: pompeiisneaks, Colossal
Re: Robben Ford Switch?
Re: Robben Ford Switch?
Wow you guys had me really hoping that you had switch that would make me sound like Robin Ford. His playing that is not his voice.
Alex
TheCageWreck and Glaswerks SOD100
TheCageWreck and Glaswerks SOD100
-
glasman
- Posts: 1446
- Joined: Wed Jan 19, 2005 10:37 pm
- Location: Afton, MN (St Croix River Valley)
- Contact:
Re: Robben Ford Switch?
Alex, you already have the switch908ssp wrote:Wow you guys had me really hoping that you had switch that would make me sound like Robin Ford. His playing that is not his voice.
Located in the St Croix River Valley- Afton, MN
About 5 miles south of I-94
aka K0GWA, K0 Glas Werks Amplification
www.glaswerks.com
About 5 miles south of I-94
aka K0GWA, K0 Glas Werks Amplification
www.glaswerks.com
Re: Robben Ford Switch?
Not on your life. I could have his amp and guitar and I wouldn't sound anything like RF.glasman wrote:Alex, you already have the switch908ssp wrote:Wow you guys had me really hoping that you had switch that would make me sound like Robin Ford. His playing that is not his voice.
Alex
TheCageWreck and Glaswerks SOD100
TheCageWreck and Glaswerks SOD100
Update
Installed the switch as per drawing #2. I used a 442 ohm / 10W resistor and had no problems with heating.
My B+ on the Output tube plates at idle with a 120VAC input is 488VDC. With the resistor engaged and hitting some low power chords in HRM mode, I'm seeing a voltage drop as low as 465V on the screen side of the resistor. With the choke side of the switch on I'm seeing no lower than 472V.
In choke mode the amp is very agressive sounding in HRM mode, the resistor does indeed smooth out the tone. Overall I like the effect and having both tones available.
I'd say go with something around 500 ohms like Dog reccomended. Any smaller is going to diminish the effect. I have some 10 ohm resistors after the rectifiers which is why I went with the 442 value.
One other thing worth mentioning is I wouldn't switch from choke to resistor mode without letting the amp sit in standby for 30 seconds or so just to be safe. I switched quickly from resistor to choke and the power tube drew around 100ma for a split second. Letting the B+ drain down keeps this current spike from happening.
TT
My B+ on the Output tube plates at idle with a 120VAC input is 488VDC. With the resistor engaged and hitting some low power chords in HRM mode, I'm seeing a voltage drop as low as 465V on the screen side of the resistor. With the choke side of the switch on I'm seeing no lower than 472V.
In choke mode the amp is very agressive sounding in HRM mode, the resistor does indeed smooth out the tone. Overall I like the effect and having both tones available.
I'd say go with something around 500 ohms like Dog reccomended. Any smaller is going to diminish the effect. I have some 10 ohm resistors after the rectifiers which is why I went with the 442 value.
One other thing worth mentioning is I wouldn't switch from choke to resistor mode without letting the amp sit in standby for 30 seconds or so just to be safe. I switched quickly from resistor to choke and the power tube drew around 100ma for a split second. Letting the B+ drain down keeps this current spike from happening.
TT