I'm converting a Hammond AO-43 amp from an L101 to a guitar amp.
I wanted to add a preamp gain pot and a master volume pot.
The preamp gain is easy enough, but I'm not 100% sure on the master volume and wanted to get some feedback (there's one person in particular to whom this isn't directed and he knows who he is, so don't answer!!!)
Here's the amp schematic and where I'm thinking of adding it is here. I was going to have connector 1 of the pot at the intersection of R323 and C307, connector 2 go to pin 7 of V8 (grid of 12AX7) and connector 3 go to ground.
I was thinking of maybe a 500K audio pot. That'll do the job, right?
PS: Doh. Can't edit titles.. Meant Hammond, of course.
I wanted to add a preamp gain pot and a master volume pot.
The preamp gain is easy enough, but I'm not 100% sure on the master volume and wanted to get some feedback (there's one person in particular to whom this isn't directed and he knows who he is, so don't answer!!!)
Here's the amp schematic and where I'm thinking of adding it is here. I was going to have connector 1 of the pot at the intersection of R323 and C307, connector 2 go to pin 7 of V8 (grid of 12AX7) and connector 3 go to ground.
I was thinking of maybe a 500K audio pot. That'll do the job, right?
PS: Doh. Can't edit titles.. Meant Hammond, of course.
My understanding of a MV is post-preamp/pre-power amp level.
To my mind pin 7 of V8 is still in the preamp.
MV is only useful if you plan to overdrive some of the preamp.
Don't even think about o/d-ing the cathodyne PI - you won't like it.
To my mind pin 7 of V8 is still in the preamp.
MV is only useful if you plan to overdrive some of the preamp.
Don't even think about o/d-ing the cathodyne PI - you won't like it.
So then you're saying it ought to be between V8 and the power tubes? Because if that's the case, I'll need a dual gang pot, right?
Or maybe I'm not really wanting master volume. I really just want a volume control, so maybe it's a terminology issue on my part. At full blast, it may blow out my speaker, as the speaker is 15W and the amp is 18W. And I can't be running an 18 watt amp full blast in my house anyway. I'd go deaf shortly before my wife shot me.
Here's that way, dual pots: http://www.trinityamps.com/ForumGallery/trinity/18wattMV.gif
Or this way:
This way, you can get some preamp grind and still have the volume lower so you can save your marriage. With no master, it might be hard to get this amp to distort until it gets loud.
Or this way:
This way, you can get some preamp grind and still have the volume lower so you can save your marriage. With no master, it might be hard to get this amp to distort until it gets loud.
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I'm trying to understand how that spitfire master volume works. Is it just the inverted signal canceling out the uninverted signal as it gets dialed closer to connection 3? And is connection 1 just floating?
Pretty sure that's how it works. See the standby on the Silvertone? It just shorts the outputs of the PI together, same type of action for the pot except the pot does it gradually. Looks like the connection floats for the Spitfire MV. It's wired as a variable resistor instead of a voltage divider.
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