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Post by thetragichero on May 30, 2022 12:05:33 GMT -5
went to the weekly flea market yesterday and walked away with a tray of tubes for ten bucks (including several ef86 in boxes)  I've got a couple of tube testers that i could test em with but since i know they have a reputation for being microphonic i figured i should build an amp to test em for microphonics. i love a pentode preamp straight into a long tail pair phase inverter so i figured the stangray would be a fun build. have more 6v6 than i do el84 (especially a friggin quad) and figured i could eek close to the same amount of power out of a pair of fixed bias 6v6. grabbed a hammond ao43 chassis out of storage and set out to planning. iron is froman ao43 besides a deluxe reverb choke (good enough and since the power section is basically an ab763 in this i didn't need such a beefy choke)  so here i am ready to start wiring the input jacks and the power supply |
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Post by thetragichero on May 30, 2022 13:53:19 GMT -5
had to take a break to cook but here's the input jacks and beginning of my preamp ground bus (only connected to the chassis through the input jacks). i like a fender hi/low setup  |
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Post by thetragichero on May 30, 2022 21:17:19 GMT -5
cooked a lot of meat, ate a lot of meat, took a nap guy most of the power stuff done, although now that i look at my upload seems that some 470k resistors got in the wrong bin. would make for a very quiet amp bit chaotic on this end but point-to-point in a small space can get that way. excited to finish this part so that i can do pretty turret board for the little bottles  |
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Post by thetragichero on May 31, 2022 18:54:55 GMT -5
heaters done, preamp done. just have to hook up the front panel controls, power tube plates and grid, and indicator led  |
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Post by thetragichero on Jun 1, 2022 15:42:04 GMT -5
everything besides led is wired up. gonna wait until we make a faceplate from plexi before i put in the led plate leads kept long in the event that my negative feedback switch is a positive feedback switch  guess it's time to throw some tubes in, plug into lightbulb limiter, and see what smokes. i have a feeling I'm going to need to change a resistor in the bias circuit but I'd rather have too much bias voltage at this stage than too little |
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Post by thetragichero on Jun 1, 2022 19:22:27 GMT -5
turns out this amp is pretty much clean all the way up so negative feedback switch wasn't as useful as it usually is (makes sense as it uses a VERY lossy tone control) so what it really needed was a tone bypass switch. I'm diggin this, even through the open back 1x12 in the shop that has a speaker pulled from a yamaha organ  have to tweak the svg to carve the faceplate (some of the fonts are too small) and figure out dimensions to build the head cab. might give a pair of 6l6s a spin in there too after i play with it for awhile |
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Post by thetragichero on Jun 2, 2022 20:41:55 GMT -5
started work on a headshell. got some nice maple-faced plywood that were scraps from a cabinet maker who used to work in my dad's shop. hardwood dowels and titebond make even the humble butt joint strong, which is good because i am a capable but novice woodworker  trying to cut the plexi faceplate on the cnc did not work (tiny metal cutting bit causes friction and heat which melts the acrylic and then breaks the bit) so we're looking to print on the back instead in the meantime here's a crappy demo from my ancient dvcam through the yamaha organ speaker in the shop via instagram |
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Post by Yogi B on Jun 2, 2022 21:30:38 GMT -5
trying to cut the plexi faceplate on the cnc did not work (tiny metal cutting bit causes friction and heat which melts the acrylic and then breaks the bit) I've had this happen, more than a decade ago, so sorry that the following is a bit vague. Extruded acrylic (which is almost always the mirrored stuff) doesn't play nicely with CNC routers. Initially, I similarly ended up with a hot mess, but did manage to get a good result by performing multiple passes (each at a fraction of the total depth) and lowering the cutting speed (both the rpm and the traversal speed, I think). |
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Post by thetragichero on Jun 2, 2022 22:01:26 GMT -5
to be honest i have a hard enough time just getting the graphic into inkscape in an importable form. my dad and his friend are more into the cnc stuff, although more wood or mdf on the big machine. i've picked up some copper clad board to try to make pcbs on the little machine. not so much for amps as pedals since it's only 6x6
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Post by thetragichero on Jun 3, 2022 21:21:17 GMT -5
all the woodworking is done, holes for handle and screws to mount the chassis drilled. hit it all with a coat of cheap flat black before tolex tomorrow  |
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Post by thetragichero on Jun 4, 2022 16:30:01 GMT -5
headshell done   attempt #2 (mirror image vinyl sticker on the inside) to make a faceplate out of plexi failed so back to the drawing board |
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Post by thetragichero on Jul 23, 2022 17:29:54 GMT -5
we etched the 1/8" aluminum faceplate using electrolysis the other day (so salt water and a 12v battery instead of sulphuric acid or whatever. much nicer since i don't like to use such harsh chemicals living on a well). hit with cheap flat black spray paint and sanded until only the etch was black. ain't perfect but it looks pretty good. discovered i don't have any feet but besides that it's DONE   |
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