Jumping in. Console conversion to (possibly Vibro-)Champazoo

FXBDM 1832

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I am pleased to report I acquired an old router for my cabinetmaking. I also just received all my passive parts from the fine folks at Nextgen in Ottawa. I am not affiliated with them but I have always had good service there. More fun updates to follow!
 

FXBDM 1832

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Some design progress yesterday. I tried to figure out where to put everything, and especially the controls.

The base for the chassis has mounting screws that line up with holes in the chassis. For the chassis to be removable, those have to be accessible. Sadly, they are on the side of the chassis that has the weirdly placed holes, not the four equally spaced, perfectly bored control holes (which makes sense since the console stereo had front controls).
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Thankfully, I kept the original pot, and it just so happens that it is a 1M, so I am now thinking that I will have a front volume control, with rear input and power jacks. I am currently thinking I’ll go with a switched IEC connector positioned where the brown plate is on the left.

I also need to position the Noval socket. The space at the right of the chassis seems optimal for layout and symmetry, but the OT is there (see the mounting screws on the top.

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The solution would probably be to move the OT to the back of the chassis, possibly over one of the holes there. I might even mount it on the top of the chassis to give me more room.

Another option would be to leave the OT alone and mount the preamp tube to the side of the octal base. That would probably imply sneaking the input signal through the other components though, and I think that’s a bad idea.

More to follow when I try to draw different layouts.
 
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FXBDM 1832

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Small progress report. I removed the tuning dial back plate and the OT, so I have a better idea of what I have to work with.

Question for the hive brain: is there any shielding advantage to putting the OT and PT on opposite sides of the chassis? (As in: the PT outside and the OT inside)
 

JSMac

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Wow, nice work so far. I wish I had the skills to do cabinet work like that. Looks like a fun project. I"m anxious to see how it turns out.

I love conversion projects. But, mine end up staying pretty industrial looking.

I've never built a kit or used any kind of circuit board so these point to point conversions are my only experience with guitar amp builds.

I made two Kalamazoo Model 1/Lancers out of Newbomb classroom record players. I thought I used the same circuits but they sound quite different from one another. One sweet and clean and the other down and dirty.



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This is a modded 5e3 made from a Pilot mono audio amp. Some switching made it very versatile.

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I just finished this 5F10 Harvard, made from a '50s Motorola console pull. An ugly but sweet sounding amp.

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FXBDM 1832

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Well, this weekend didn't go well.

I started gluing the oak facing I wanted to use to have a contrast.
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Then I routed it to size so it would just cover the endgrain, and promptly ripped off a large sliver on the side
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So without thinking much, I decided to try and use the beaded roundover bit I had to see if I couldn't correct it, and my plywood failed at the bent portion, which I should have foreseen.
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So now I have a few options. I can try sawing the back inch or so of the case, which would leave me with enough space inside, but would probably be a bit difficult with the equipment I have.

I could also Tolex it to cover up, which I would feel ambivalent about, and I'm not sure how I'd do a nice job of the curved portion in the front.

Or, I could start over. I could even go and buy some slightly thinner plywood, or even try the same process with pine.

While I was reflecting on that, I decided to drill the holes for the noval socket and the second input jack. The stepped drill bit did just fine in the aluminum chassis. I probably should have used the drill press, but the hand drill worked fine
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Mongo Park

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Oh man it was looking so trick. I might be your router bit was set to deep. It is hard to tell or maybe it was not sitting at a 90 degrees to the cab. Also you should note the direction the router bit turns. if it is turning UP on the wood it it cutting it is more prone to tear out the wood. If it is turning DOWN it tears out less. Small repeated passes tear out less. If the router tilts out of the 90 degrees it will cut where it was not intended. Sharp router bits tear out less. Burn marks come easier from dull bits.
If you rebuild maybe do the round over by hand with a file and hand plane. Pre router them first, course their makes the inside corners not the same as post routering.
Looking closer at the photo maybe set the router cutting part of the bit so it is not touching the plywood veneer. Or use a smaller bit so it is only cutting the oak facing. If you don’t have such a bit is it’s possible make the facings thicker, course this changes the look of the cab.
I this is about all I can suggest from the photos
Cheers Ron.
 

FXBDM 1832

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Thanks, I appreciate the input. I think I should have foreseen that the bend would cause the plywood to be more fragile. I was basically using the wrong bit too, It's a beaded roundover whereas I wanted roundover. I bought the wrong one and hadn't had a chance to go back to Canadian Tire to exchange it, but I wanted to test.

Ah, well, you live you learn, and being careful and not pasting over my errors is why I made this thread.

I think I'll just start over. The bending part took me an hour total, and I still have enough plywood (although I'll also buy some pine just to see) I can make this one into a workshop amp.
 

Mongo Park

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Looking at the other photo the router bit is cutting to deep ( as in it is sticking out to HIGH from the router base) and is cutting into the plywood cutting the veneer When you set the router bit place a ruler on the router base plate and push the ruler up to the cutting part of the bit. Then you can check that the round part of the bit is still below the router base. You have yours set a little to high above the router base plate. Also place the router on the cab to see that the bit is not so big it is cutting the cab you only want to router the facing. Maybe the bit is to big as well as set to hog from the base.
 

Mongo Park

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If the router bit is right size and depth to not touch the plywood it will be fine, fragile veneer will be safe.
 

dankilling

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Do you have a table saw or a circular saw guide? I’d just take the messed up portion off. Even if you mess it up, it’s worth a shot instead of having to start all over.
 

FXBDM 1832

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I don't have either, but I have been looking at a few classifieds.

In all fairness, there are a few things bugging me about this cab, for example, it's slightly tapered towards the top, and that makes it harder to place the chassis.

Also: I made the curves with a 3,5" radius, so they would match the 7" speaker hole, but after I did that I realized that if the speaker broke, I'd have to find another 7", whereas if I make the curves 4", and the hole 8", I can mount an 8" speaker no problem if that one conks out.

(the speaker is sitting on a baffle, so it wouldn't show)

I might try both, like I said. Push comes to shove, I mount a Little Gem in the worse looking of the two.
 

JSMac

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Sorry that you ran into trouble with the cabinet. It looks like a nice design and I hope you get it worked out.

Any more thoughts on what you will do with the amp. It looks like there are a lot of possibilities there.
 

FXBDM 1832

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Well, good news, I managed to chop about 3/4 inches off the cabinet, and mostly straight too! I used an old panel saw I built about 15 years ago. Super long blade. It made it relatively straightforward.
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Now the face I just cut is fine when looking at it quickly, but it’s not straight enough to glue something on, so I will most likely use the other face as the front.

Crisis averted!

Now back to the electronics, I spent the evening making sure my schematic was well done, and trying to set my grounding scheme straight (pictures to come when I am a bit further along).

One thing I noticed going over my PT leads is that I have only one 6.3v lead. Looking at the schematic, this seems to be normal for this amp. One live lead and one bare wire ground.
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Seems to me that this will not be optimal for hum suppression. However, I am thinking that if I bring both of those wire to a terminal, I can start twisted pairs from there and wire the amp normally? Or is there a chance this is 6.3v dc and that I need something more involved?
 

FXBDM 1832

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Sorry that you ran into trouble with the cabinet. It looks like a nice design and I hope you get it worked out.

Any more thoughts on what you will do with the amp. It looks like there are a lot of possibilities there.
For now the plan is for a straight up 5f1 build (but p2p). It’s my first build so I don’t want to bite off more than I can chew.

I must admit it seems a shame to leave all that real estate empty, though. I might add a tremolo down the road.
 

FXBDM 1832

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Looking at the Heater situation, I found someone claiming that Fender sometimes did use the chassis as the return wire of the heaters, but that this was far from ideal. So I'll go forward with my terminal block plan.

I guess I am getting pretty close to the AC wiring stage. I'll do that and then test to see whether the power transformer even works.
 

FXBDM 1832

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Ladies and gentlemen, we have soldering!

But first, a fun anecdote, I dropped a magnet in it,
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and I guess my chassis is not Aluminum after all!

I filed the hole for the power socket and soldered the ground to a convenient tab.
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And then the mains wires to the switch and back. I cut the white one a bit too short and it doesn’t look very neat. I might re-do it. I also twisted my heater wire and mocked it in. I thought I had bought two colours of 18awg solid, but apparently I only got white, so I sharpied one side.
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I also finished gluing up the face panel.
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Next up, I need to plane that face plate, and think of a way of making sure the hole for the front control is well located and concentric. My build sequence is probably going to be front hole - mock fit - speaker hole - rough cut - glue up and finally a trim pass with the router.

Electronically, go buy some terminal blocks for the heater setup, and then pop the tube sockets in. I will also need to build a lightbulb limiter at some point to test the PT

Stay tuned, and thanks for listening!
 




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