Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: HommeMarrBuckley on May 27, 2013, 06:28:43 am
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Hello all,
I am very new to amp building and am starting a Bassman 6g6B scratch build. On the bass channel, I was thinking about putting a switch on it for different bypass cap values. I was going to use (25uf (stock) and .68uf (mod). I am not good at all with the schematic and was hoping someone could draw it out in layout form the best way to implement it. I was reading about this and was also concerned about switchable popping. I just would like the input from those more experienced. I believe it requires a spdt, as well.
If responding, please don't direct me to another mod unless the layout is very similar to 6g6 B with double input jacks.
Thanks
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Since the .68 is much smaller than the 25uF,
why not just put them in parrallel and put the switch
on the 25 to turn it off or on?
Since there is also a resister, I don't thnk it will pop.
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http://www.el34world.com/Forum/index.php?topic=5621.0 (http://www.el34world.com/Forum/index.php?topic=5621.0)
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Here's a couple of suggestions
(http://farm9.staticflickr.com/8135/8854773497_1e0de6e594_o.png)
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I am not good at all with the schematic and was hoping someone could draw it out in layout form the best way to implement it.
I like 6G6's idea. I'd do it like this...
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Sluckey and others,
Thanks so much for the image and input. If I wanted to use a push pull pot for the volume (instead of a switch) how could I wire that? Someone stated about using a pot and I like that idea (than finding and drilling a hole for the spst).
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Wire it exactly the same. The only difference is the switch is on the pot rather than beside the pot.
(http://www.hoffmanamps.com/MyStore/catalog/images/IMG_2249.jpg)
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Does it matter if schematic/layout calls for 250k L volume pot and I would be most likely using 1M Audio spst (like pictured)?
Thanks
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If you want your build's controls to respond like the original 6G6B's, then yes it will matter.
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Dang
Can't seem to find a 250K Linear SPST pot.
Someone mentioned wiring another 1.2 or 1.5k resistor (for more Marshally sound)
How would that look?
I know this is a lame question but is that spot directly under the pot a grounding point?
After this, I am done pushing this, I appreciate everyone's help. Sorry if I annoyed anyone.
Thanks
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Oops. wrong post
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Can't seem to find a 250K Linear SPST pot.
Here's one... http://www.tubesandmore.com/products/R-VPP-250KL (http://www.tubesandmore.com/products/R-VPP-250KL)
I know this is a lame question but is that spot directly under the pot a grounding point?
yes
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Someone mentioned wiring another 1.2 or 1.5k resistor (for more Marshally sound)
How would that look?
Well, your plan to build the 6G6B Bassman is an awfully specific and slightly quirky model. If it were me, I'd build the amp stock (or very close) to begin with to hear what it normally sounds like.
Of course, if you leave room you could always add new components later if you want to alter its sound.
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I'm not sure about which pot of the amp you want to have with the switch with the purpose of insert and exclude one of the two capacitors (0.68 - 25uF)
but I think you need a PushPull Pot, not a Common Pot with switch
with a Common Pot, you can't turn the pot without act the switch at the start of the rotation
with a PushPull Pot you can turn it independently by the activation of the switch
K