2Watt Sub Miniature Plexi
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2Watt Sub Miniature Plexi
I have had so much fun playing with the subminiature tubes I decided to try miniaturizing a JTM45 next. I got the 1st prototype board etched last night and am waiting on some small PCB drill bits to come in before I can drill the board and populate the components. While I am waiting I thought I would bounce a few ideas off you guys and see if it sounds like it would fly or maybe you may have a better approach or an added feature that I could add. I am trying to design this so it fits in the same chassis as the Lil Devil and so far that is my only limiting factor.
The amp/PCB I have designed has 2 channels just like it's big brother. Unfortunatly I didn't have enough room for two seperate vol controls. I though about concentric controls on one pot shaft but haven't found a supplier for those yet. So the amp as is stands right now has a single shaft dual pot for the Vol I and VOL II and it controls both channels. I plan to add a small 3 pos switch like the Bright switch on a Express. The switch will enable you to select between Channel I, Both Channels or Channel II. Kind of a built in A/B/Y thing. I could also put this on a foot switch if you leave the front panel switch in the both position you could then use a footswitch. Only problem is this really doesn't allow for two different vol settings for each channel.
I'll try and post a few pics as I go along
The amp/PCB I have designed has 2 channels just like it's big brother. Unfortunatly I didn't have enough room for two seperate vol controls. I though about concentric controls on one pot shaft but haven't found a supplier for those yet. So the amp as is stands right now has a single shaft dual pot for the Vol I and VOL II and it controls both channels. I plan to add a small 3 pos switch like the Bright switch on a Express. The switch will enable you to select between Channel I, Both Channels or Channel II. Kind of a built in A/B/Y thing. I could also put this on a foot switch if you leave the front panel switch in the both position you could then use a footswitch. Only problem is this really doesn't allow for two different vol settings for each channel.
I'll try and post a few pics as I go along
Last edited by UR12 on Fri Jan 29, 2010 3:52 pm, edited 2 times in total.
Re: 2Watt Sub Miniature Plexi
Or jumper the channels like a lot of guys end up doing inside the amp.
Does sound like an interesting project.
Does sound like an interesting project.
Tom
Don't let that smoke out!
Don't let that smoke out!
Re: 2Watt Sub Miniature Plexi
In the middle position on the switch the channels are both engaged or jumped.Structo wrote:Or jumper the channels like a lot of guys end up doing inside the amp.
Does sound like an interesting project.
Re: 2Watt Sub Miniature Plexi
Might be too late, but you might try putting a "balance" knob on the back. Would dictate the mix of regular and bright channels. At least for me, tend to adjust the mix of the two and keep it there.
Re: 2Watt Sub Miniature Plexi
Never too late. I am still prototyping. I ended up makeing 5 board revisions before the Lil Devil was done. This first one will be the basic design and then I want to start to add some of the better marshall style mods to see what it can do. I have also been thinking about the 2 input with cascading stages in the front end. That also may be a way to go.gearhead wrote:Might be too late, but you might try putting a "balance" knob on the back. Would dictate the mix of regular and bright channels. At least for me, tend to adjust the mix of the two and keep it there.
Re: 2Watt Subminiature Plexi
Here's someone who can do the concentric pot just like you want-UR12 wrote:I have had so much fun playing with the subminiature tubes I decided to try miniaturizing a JTM45 next. I got the 1st prototype board etched last night and am waiting on some small PCB drill bits to come in before I can drill the board and populate the components. While I am waiting I thought I would bounce a few ideas off you guys and see if it sounds like it would fly or maybe you may have a better approach or an added feature that I could add. I am trying to design this so it fits in the same chassis as the Lil Devil and so far that is my only limiting factor.
The amp/PCB I have designed has 2 channels just like it's big brother. Unfortunatly I didn't have enough room for two seperate vol controls. I though about concentric controls on one pot shaft but haven't found a supplier for those yet. So the amp as is stands right now has a single shaft dual pot for the Vol I and VOL II and it controls both channels. I plan to add a small 3 pos switch like the Bright switch on a Express. The switch will enable you to select between Channel I, Both Channels or Channel II. Kind of a built in A/B/Y thing. I could also put this on a foot switch if you leave the front panel switch in the both position you could then use a footswitch. Only problem is this really doesn't allow for two different vol settings for each channel.
I'll try and post a few pics as I go along
Vlado Hansal
hansal@mec-pickups.de
Last edited by dr. who on Thu Jan 28, 2010 7:34 pm, edited 1 time in total.
Re: 2Watt Sub Miniature Plexi
Amazing! This will be great! Thanks much!
Re: 2Watt Sub Miniature Plexi
Thanks for the heads up on the pots. I contacted another mfg and he is sending me a sample . I was given a price of $18.50 ea if I order 100 and that doesn't include the knobs . I also found some small drill bits at Harbor Freight (God I love that place ) and hope to have the board drilled this evening so I can start populating it. The ones I had on order didn't ship until yesterday.
Re: 2Watt Sub Miniature Plexi
Thats it! I'm ordering 4 x 6" Alnico's from Weber and starting to build a slanted 4 x 6". I have no idea how it will sound but I have to have my mini Plexi half stack. Great idea to use the same chassis as Lil' Devil.
Re: 2Watt Sub Miniature Plexi
I have a 1 x 12 cab coming in that I want to try the amp through if it ever gets here. Even though I will be using the same chassis I think I will try and do a scaled down version of the Marshall head cab instead of the Lil Devil style cab.MCK wrote:Thats it! I'm ordering 4 x 6" Alnico's from Weber and starting to build a slanted 4 x 6". I have no idea how it will sound but I have to have my mini Plexi half stack. Great idea to use the same chassis as Lil' Devil.
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Re: 2Watt Sub Miniature Plexi
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Last edited by frequencycentral on Mon Apr 12, 2010 6:29 pm, edited 1 time in total.
Re: 2Watt Sub Miniature Plexi
Marshall head cab style is what I have in mind too. Please let us know how it goes with the EVM12L once you get it. All the bestUR12 wrote: I have a 1 x 12 cab coming in that I want to try the amp through if it ever gets here. Even though I will be using the same chassis I think I will try and do a scaled down version of the Marshall head cab instead of the Lil Devil style cab.
Re: 2Watt Sub Miniature Plexi
frequencycentral wrote:Dana - what tubes are you using for this amp? 5902 and 6112?
Rick
Yes, 5902 and 6112
I am still waiting on the speaker cab to come in but I'll keep ya posted.MCK wrote: Marshall head cab style is what I have in mind too. Please let us know how it goes with the EVM12L once you get it. All the best
Here is a couple of pics. I will be drilling the rest of the holes in the PCB today and maybe get some of the board populated tonight.
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