jer_vic wrote: ↑Tue May 07, 2024 10:41 pm
Kit arrived today from Weber. Now the fun begins..... First step is shellacking the cabinet.
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A word from someone who has screwed up this procedure. There are two ways to go. One is spraying the cab with nitrous lacquer and letting it go dark of its own accord. The second one is to use shellac but don’t use the recommended amount on the on the jar use about half that or less so the coats are much thinner.
Thanks. I have flake shellac that I dissolved in 99% isopropyl alcohol. The colour I chose turned out to be fairly close to the original tweed. I put on eight coats, and the colour difference is quite subtle. I would have liked it slightly darker, but not enough to go back to the hardware store and buy another, darker pack of shellac flakes. I'll let time do the rest of the work for me.
I started on soldering up all the components and leads to the eyelet board. There was something wack with with my cheap soldering station at first - it didn't seem to be able to get up to temperature. I finally noticed that part of it was slightly unscrewed, and it wasn't getting a good enough connection to the heating element. Things went much better after I figured that out. I have to drill a couple holes in the chassis, and enlarge one of the existing ones, and then it will be time to dry fit the board and components, measure my remaining leads, etc....
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I believe you want "garnet" shellac. It takes more coats than you might expect to get a deep color. I mix it so it's a pretty dark brown in denatured alcohol, but not so thick that it won't dry properly. I have only used it on wood, so YMMV with tweed.
Any alcohol should do. Don't spill adult beverages on your shellac finish or you will have a bad time. I add a coat of paste wax for protection, lacquer then wax is even better.
Thanks. I have flake shellac that I dissolved in 99% isopropyl alcohol.
You sure about that??
Isopropyl is rubbing alcohol. Shellac is dissolved in methanol.
Yeah. The interwebs assured me it was fine, as long as you have a high enough alcohol percentage. Also, that it may take a little longer to initially dissolve the shellac.
Finished drilling/enlarging the extra holes in the chassis. The switch I bought for the voice/boost function was larger than an input jack, so had to enlarge one of them. Also needed a hole for a 2nd output jack, and 1 more to mount the OT. Test fit (again) into the cabinet with the OT mounted to make sure the speaker fits. Close, but success. Also finished wiring and soldering the eyelet board. Next to dry fit everything and cut my leads and OT/PT wires to length, before final assembly.
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Looks nice so far! Good on you for doing multiple test fits. For future builds, if you want to keep the two input jacks and have a hidden boost switch, here's a way to do it with an optional two button foot switch. https://ampgarage.com/forum/viewtopic.p ... al#p454393 I'm guessing voice/boost is cathode bypass?
maxkracht wrote: ↑Thu May 23, 2024 8:46 pm
Looks nice so far! Good on you for doing multiple test fits. For future builds, if you want to keep the two input jacks and have a hidden boost switch, here's a way to do it with an optional two button foot switch. https://ampgarage.com/forum/viewtopic.p ... al#p454393 I'm guessing voice/boost is cathode bypass?
Thanks. I think the voice/boost is that kind of thing. Here's the part of the circuit for that:
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jer_vic wrote: ↑Thu May 23, 2024 10:15 pm
Thanks. I think the voice/boost is that kind of thing. Here's the part of the circuit for that:
Yep, my way only gives you one boosted setting but you get to keep the hi/lo input settings and get a footswitch option. If you add a pair of resistors across your switch it won't pop when you change settings. Resistor value doesn't matter too much, too small and the caps will start to boost before being switched in, too large and it will take too long to charge the cap and stop the pop, I usually go somewhere around 100k. What is that pot doing?
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Looks good jer-vic!
Always liked the idea of this design due to its simplicity and versatility. I’ll have to build one some day. Eager to hear your impressions of how it sounds when you are done.
maxkracht wrote: ↑Fri May 24, 2024 12:38 am
If you add a pair of resistors across your switch it won't pop when you change settings. Resistor value doesn't matter too much, too small and the caps will start to boost before being switched in, too large and it will take too long to charge the cap and stop the pop, I usually go somewhere around 100k.
Interesting. The layout for the Weber Maggie kit (which is essentially the two-stroke, and in retrospect maybe I should have started with (but didn't know about) rather than their 5F2A kit) shows resistors across the switch.
jer_vic wrote: ↑Fri May 24, 2024 7:22 pm
The layout for the Weber Maggie kit...shows resistors across the switch.
Yep, it's generally a good practice to add them when you are switching caps in and out. I like the input jack drawing on webers layout much better, and the 220k bleeder resistor on the first filter cap is also a good idea.
