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WRGKMC

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WRGKMC last won the day on April 16 2018

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About WRGKMC

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  • Birthday 11/01/1957

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    Houston

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    Music, Recording, Electronics, Guitar Building

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    Electronic Tech, Musician, Luthier, Audio Engineer, Video Producer

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  1. I doubt a 6V6 in that amp are power tubes, Not rectifier or tremolo tubes. The tremolo is handled by the 6SQ7 tube. The foot switch connects between chassis ground and the 500K pot that controls the tremolo. What the switch essentially does is completes the circuit to the tremolo potentiometer. when the switch is off, the pot does nothing. When the switch is on it adds a ground to the end leg on the potentiometer. The schematic can be found here. https://www.tdpri.com/threads/gibson-ga-40.904898/ Reading a schematic is like reading a road map when driving. If you cant read a road map its unlikely you can read a schematic. Both are abstract drawings involving using abstract images to depict actual objects. Like a road map, a schematic shows where the electricity flows. Reading a schematic and being able to trace every step the signal takes is like reading a road map and knowing which roads you need to travel. An education in electronics teaches you what every component does so you know if the signal is properly manipulated by each component. Test tools let you look inside the circuits and see what the invisible thing called electricity is doing. From there Math is used with the measurements taken to determine if the readings are within tolerance and whether components are doing their jobs properly. If you use these tools and think your way through the problem then you are simply guessing which makes you wide open to making the wrong guesses.
  2. I've tried various PA speakers 10's and 12's in guitar amp cabs over the years. The best you can say for most is they make sound, but that's about it. There are a few vintage Altec, EV and JBL's that can sound good in a guitar amp but most new stuff is specialized. Most are designed to be run as woofers in 2/3 way cabs and produce mostly low frequencies. Many have lower SPL levels and a guitar head will have much lower volume levels using them directly. Most guitar speakers on the other hand will use high efficiency, 95 to 110dB SPL PA speakers will have a 95 or lower SPL in many cases and are designed for high wattage. Second PA woofers will often have heavier paper to produce low frequencies without distorting. The specs may say it has a top Frequency response that covers guitar frequencies but given the fact most are designed to be run with a crossover and other drivers handle the highs, those upper woofer frequencies aren't very good for a guitar amp. Overall, they typically sound bassy/muddy run directly from a guitar head. Guitar speakers on the other hand specialize in being overdriven, Have high SPL levels, and have lightweight cones that respond quickly and articulate the light guitar strings well. As Daddy and Steinberger says, there is no problem running a guitar direct or micing an amp through a PA so long as the raw output of a guitar is properly gain staged colored to sound good through a PA system. Most amp modelers typically rill off the highs and lows, ad electronic drive and highlight the mids and highs of popular miced amps. Of course micing and amp is the other way of doing it. Many of the new modeling amps also use full frequency amplifiers and full ranged speakers. I bought a couple of Peavey Blue Marvel speakers which are full frequency and have a flat full range up to 10Khz. Seems like guitar amps have taken the full revolution on this. Back in the 30/s 40's the goal was to have a full frequency guitar amp to make the hollow jazz guitars sound good. Now they're back at it again except the coloration comes from the modeling instead of the amp and speaker . This way the digital modeling can take advantages of the extended frequency response when switching from one amp model to the next.
  3. Definitely has that 40's 50's automobile, art deco look. It looks like something Dan Electro might design. In regards to the first pic with the slanted pickups. My first though would be you might have issues with the tone. Tilting pickup towards the bridge typically gives the Light strings more treble and the heavy strings more bass. There again, Hendrix got great tones put of playing a right handed Strat left handed so It may not matter very much.
  4. Yes, I used something similar on violins back in the 60's and they were old news then but they worked a bit different, they mounted between the end of the string and tail piece and shortened the string length when cranked down. This one bends the string which I haven't seen before. I've also used Hipshot tuners made for Bass which drop tune to a fixed pitch. Another unique gadget are these multi function capo. https://www.ebay.com/itm/New-Multifunction-Capo-Open-Tuning-Spider-Chords-For-Acoustic-Guitar-StringsLI/303276251565?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D1%26asc%3D20131003132420%26meid%3D0746f62b993d4ca69e951978adbd2592%26pid%3D100005%26rk%3D5%26rkt%3D12%26mehot%3Dco%26sd%3D113308869249%26itm%3D303276251565%26pmt%3D1%26noa%3D0%26pg%3D2047675&_trksid=p2047675.c100005.m1851 I bought one for $6 and its actually kind of neat. I was doing some things where I had it placed on the 5th fret holding down the two E strings and then I could play augmented chords below it and above it on the fret board. Not something you'd use every day but it does let you play stuff you've never heard before on guitar. A bit tricky to set up. It pulls out and expands to your fret board then you have to align the stoppers to the string centers. The adjustments are stiff, likely for good reason but it does work.
  5. I have similar fine tunes on my Violin. Seems like someone got the bright idea of making one that will work on guitar. The ones for the heavy strings are designed mainly tp tune down to lower tunings. The unwrapped strings can be pitched up a full note. I haven't tried them but if they work anything like the ones on a fiddle they can be used to fine tune or drop a pitch accurately. https://www.ebay.com/itm/Pitch-Key-PK01-Non-Evasive-Preset-Alternative-Tuning-For-Guitars-Drop-D/272792856628?_trkparms=aid%3D1110002%26algo%3DSPLICE.SOI%26ao%3D1%26asc%3D20190711095549%26meid%3Dcce76bc8ea7b41ce8475dcf527856e9f%26pid%3D100047%26rk%3D4%26rkt%3D8%26mehot%3Dpp%26sd%3D231192541653%26itm%3D272792856628%26pmt%3D0%26noa%3D1%26pg%3D2047675&_trksid=p2047675.c100047.m2108
  6. I have had transistors and caps create similar effects, in fact I just repaired a high end stereo that had a blown channel. It would make a weak sound till you turned it up then it would blast. The sound quality was distorted however and I knew the cause was a blown transistor. I had left the volume maxed when I turned it on and blew a middle stage transistor so only a half wave was coming through. I thought for sure it was the power transistors because of the heavy AC hum so I changed them first but no soap. When testing I saw a crack developing in the Transistor that was bad so it confirmed the readings I was getting. A foot pedal is much more likely to have a loose connection vs a bad part. Pedals like the Boss are even polarity protected with a diode so the chance of zapping something with the wrong type of adaptor is nill. I would advise using a zero hum AC adaptor like a Dan Electro, Boss, or a brick that has the correct current levels. I have seen those pedals plugged into a generic wall wart and had them create all kinds of hum due to their poor regulation and filtering. The pin on the jack needs to fit the plug properly too. Non standard 9V adaptors can have different sized barrels and make a poor DC contact. That plug has a switch that toggles from battery power to the adaptor power which is activated when the proper sized jack is plugged in. A non standard DC jack may cause intermittent power and jump between wall power and battery if you have one in there. Likewise the input jack on most pedals is a 3 contact plug and the ground is completed to the circuit when you plug in. Loose PCB connections and cold solder joints are another possibility. Most circuit boards are wave soldered and occasionally a contact doesn't get properly joined. Either the fl8ux fails to clean or the temp isn't right and you wind up with a cold solder joint. This is where the two contacts are touching but the two metals aren't atomically joined with heat. Over time the lead in the solder exposed to oxygen tarnishes making it an intermittent contact. When you increase power like when turning up the volume, the current jumps the oxidized contact and it works for awhile. Then as it sits unpowered the tarnish comes back making it a bad contact again. The only way to find these kinds of bad contacts is to inspect the board and reflow the solder joints on anything that looks suspicious. In extreme cases a tech will signal trace the circuit using a buffered amplifier and listens to the input and output of components till he pinpoints the exact component that's failing. using heat and cold can also contract and expand the circuits and reveal component failures. Something like that boss consists of a low cost op amp if I remember right and a couple of clipping diodes. Its "extremely" rare when an op amp becomes intermittent. If thay fail they don't magically fix themselves and start working again, so I don't believe you have any bad components based on your symptom. Again, its most likely intermittent power or signal flow and both of those can be narrowed down by swapping cables and power supplies. Running it on a battery vs a wall wart of different cords. Plus the Boss pedals are buffered. If it happens turned on it should happen buffered is its power or a cable.
  7. Many inexpensive cables used connectors which are simply riveted together instead of being securely welded. They combine layers of plastic for insulation between the metal and if you know anything about mechanics plastic and metal expand at different rates. Over time the contacts get loose and then make intermittent contacts. Loosen the covers on the connectors and make sure there aren't any cats whiskers touching from hot to ground inside. Also take the connector tops and sleeves and see if you can twist them. Dollars for donuts one or more is loose.
  8. $29? That's about what I'd spend on a stand. Looks simple enough and enough to get it off the floor. There was one I saw that looked pretty cool. Its a cross between a guitar stand and mic stand together except its designed to hold an amp. I'd find this handy in a studio because it reduces standing waves when you get the cab off the floor, plus you don't need another mic stand to haul around or trip over. It does it all in one simple unit. It looks a bit flimsy but I read a bunch of reviews and they said its very sturdy. There is a version with a boom that is $49 and one without for $32. I'd likely get the one without the boom then buy a boom separately. I probably got enough goose necks and parts around to rig something up too.
  9. This should be a lesson to you. There is no such thing as preventative repairs in modern electronics. If it ain't broke don't, mess with it. Chances are you overheated the switch and wiped it out. Most modern switches are made of nylon or plastic. If you don't solder for a living you probably don't know how important it is to heat sink the connections on the cheap parts made today. Most everything made today is robotically wave soldered with timing that is computer accurate. They don't get overheated when affixing them to the boards. If you don't solder enough and try to match the speed so it doesn't overheat it only takes a second too long to fry that switch on the inside and melt plastic over the contacts. The Only thing you can do is to replace the switch again. Be sure you clean up the solder points using a little nail polish remover and a Q tip too. The solder resin you leave behind has small articles of lead which can bridge traces if you don't clean up that stuff after soldering. This is very important on new circuits that use such low voltages. it only takes the resistance of a fingertip to bridge a connection. Leftover rosin is corrosive too so keep it clean. If you still have the used switches you can test them with a meter and see if one is still good. Otherwise, get a new one and change it out. In the future change only the part that fails. These aren't automobiles where you change an entire set of brakes at the same time or tube amps that have all the tubes or power caps at the same time. They are designed to be disposable. When they break you buy a new one. As A tech I've learned it is unwise to look for trouble. Robotically built gear is much more precise then something hand built so change parts as the fail only. Don't do something stupid like Cleaning all the pots in a piece or gear when one gets scratchy either. Clean only the one that's giving you the problem and leave the rest alone. Cleaning may temporarily rejuvenate a dirty pot by removing dirt trapped by lubricants inside the pot. When you clean good pots it strips the lubricants and accelerates the wear on the carbon pads. you in fact accelerate their failure by trying to clean them. Pots, switches, connectors, any moving parts or parts that see movement are designed to work their maximum time without being cleaned so beware. Electronics is not the same as it was in the past. Engineers have made the jobs of electronic techs obsolete by designing parts that will work without maintenance and should only be replaced when they fail. (if you can even do that without screwing up the boards, components are so small now you need a microscopic soldering station for most components these days. Multi layers boards make it dam near impossible to solder most properly too.
  10. Just the opposite in many cases actually, they used allot of 300K linear pots for most guitars with a P90/single coil pickups but not exclusively. Firebird III's with three P90's used 500K Audio. My guess is the third pickup increased the impedance enough where they needed to raise the volume pot resistance to maintain signal strength. Some of the volume pots were as low as 100K linear on some of their vintage guitars. Back in the day they weren't particularly interested in getting any kind of overdrive from an amp. Electronics were strictly a matter of matching the clean acoustic tone on most instruments without any distortion. Add to that many 300K pots can have at least a 20% variance so you could easily have 60K ohm difference either way making a 300K pot reading closer to a 240 or 360K depending on the batches made. it can change over time as carbon wears off too. Gibson did build some oddball stuff over the years and I wouldn't be surprised what you might find in one of their signature custom builds or even some of their newest builds. The LP Pro and recording model uses a 1K linear pot for treble and 2.5K linear for bass, but they also use oddball pickup impedance plus an output transformer. It uses low impedance output transformers so you can plug in a balanced cable and play through a PA/mixer direct. If you can think it up they've likely tried it at one time or another, they did allot alot of experimentation trying to find the best tone vs cost. I was reading about their modern stuff using multi tapped pickups but couldn't find that link again. You can dig through their archives is you want here. http://archive.gibson.com/Service/Tech/Schematics/ Its has mostly contemporary and popular vintage models, but it isn't complete. I spent years going through most of them looking for new wiring ideas and you'll find most new Gibson's use 500K Audio pots throughout for both tone and volume. same with Epiphone.
  11. WRGKMC

    Not Bad

    Here are the finished instruments together. As you can see the Tele finish came out a bit lighter and more transparent due to the fact I Mixed the stain and Tung oil together for the first few coats and the stain didn't penetrate the grain as deep. I will likely re-fret the tele neck is short order as well. The stock frets were worse then I suspected. You cant tell how bad the frets are till you get it strung up under tension and the truss adjusted. I was able to level them but these are basic medium, not high or jumbo which I prefer. I cant get much grip bending strings and get allot of friction from the fretboard. Overall the tone is very different from my stock tele. Its even more unusually nice then the Strat was. The cleans are almost Zither like in the way they resonate clear and acoustic like. No problem cranking the thing up either. Here are two tracks with each of the guitars playing lead. I apologize ahead of time, I've been suffering from a bad case of Trigger Finger which I need to get treated so the leads are pretty basic stuff, still they give you and idea how each guitar sounds gained up. This is the Tele This is the strat Here are the two together. I'm still deciding is I want to swap an all maple neck to this tele. The Pickguard being more red matches the finish a bit too closely so I may get a darker one like the Strat has. I only had those Smaller Fender Amp type knobs for the Tele. They are a bit smaller but do give it a Custom Tele look. I wired the two 500K pots as independent volumes for each pickup which I actually like and I reversed the switch towards the tail which I've done on several of my builds. More suitable for my playing. The compensated 3 saddle Tele bridge was the first for me and even though the staggering is about 5mm it worked out surprisingly well. A standard tele bridges with 3 saddles can be fairly accurate by using string height to kelp compensate the individual strings. You can get a nearly ideal height across the fretboard with these compensated saddles. It does sound different then having 6 individual saddles too. I think the string pairs on single saddles provide some of the unique Tele magic. I didn't notice that bridge gave both options, Through body or top load. I could have mounted a Bigsby on this one if I wanted. I do have one too but its black and wouldn't match the colors very well. Anyway, that's the end of these two builds. I have one more New neck I'll eventually give a home but again, I'm not in any big rush. I likely have all the parts I need too.
  12. You shouldn't need much more then that for practice, rehearsals or club gigs. If you need it louder just mic the thing. The only thing you'll need now is get an amp stand. I'm in the market for one myself. This one would be my choice. Sturdy, Simple, light, inexpensive and folds flat. Some of the taller ones would worry me, they look to be a bit tipsy and the low ones would force me to bend over with a guitar on my back.
  13. I'd need to see the schematic for that Masco before telling you if its even possible to wire them the same. As a novice your knowledge is limited to the knobs of the front of an amp and dreaming of how you'd like it to sound but actually wiring a circuit to sound the same isn't always possible. In an amp like the AC30 the treble and Bass run in parallel circuits and are amplified with their own gain stages. That's much different then an amp that has a simple passive roll off tone filter like many of those museum pieces used to have. Some of that vox tone comes from the power tubes used too. Early Vox amps used a tone control and it wasn't placed were most put them in the preamp circuit. They placed them after the phase inverter in the power amp circuit which is quite unusual. Its also probably the reason so few vintage Vox amps survived. The first repair shop I worked in had dozens of vintage Vox amps abandoned by customers. They had unstable power amp design and when the power tubes went it typically gutted the power amp and transformers making it too expensive for people to repair so they'd abandon their amps to the shop instead of paying the diagnostic fees. In any case this site has some tone circuit diagrams you might want to use. http://www.voxshowroom.com/uk/amp/ac30_tb_hood.html
  14. WRGKMC

    Not Bad

    I like that story where Eddie Van Halen would interview his guitar technician. He's hand the guy a box of spare parts and give the guy one hour to hand him a fully assembled and tweaked instrument. Eddie is a very competent guitar tech himself so he knows what to look for in his hired help and as a player. That test is a perfectly achievable challenge for not only for a good guitar tech/luthier but for many guitarists too. As they say the show must go on and being swift and accurate when it comes to guitar maintenance can make a huge difference in how well that instrument performs. You wonder why a soldier isn't just taught to shoot his rifle, he's taught to disassemble then reassemble his weapon blindfolded. Not all battles occur in daylight with 2 good eyes. What happens if he's hit at night and has to convert two busted weapons into one that's working. I've done shows where I've had to pull magic tricks out of my rear end in order to play a show and not all of them are as simple as rigging an AC cord left at home. I've tad to do open heart surgery on instruments and amps when we were all too poor to carry spares. Guitar building may not critically important. I know many players who played for many decades and still don't know the proper ways to put a guitar string on, but i realize that's simply because they were never shown the proper way of doing it. A little screw driver time can turn a sour instrument into a major player if you learn how and remember what you learn. It may not save anyone's life but it can make the difference between putting on a show or looking like a fool because your gear acts up and you're clueless to fix it. I have a long list of things I've done over the years to get through a show. many were invented on the spot when tragedy strikes. It can be anything from a blown tube to a busted cable. I drove 50 miles to a beach gig once and found I had a cracked preamp tube whe I got there. There was no way I'd be able to drive home and get another so we put the word out to people there asking of anybody had an old tube amp or radio at home. Sure as heck some guy a fe houses down had a table radio with a 12Au7 tube in it which I borrowed. Sounded really good too. I wouldn't have knowing to do that if I didn't have some experience working on gear. We made it through the show and a few thanks over the PA made the guy feel like superman coming to the rescue. A little basic electro mechanical experience gained from doing your own build can go a long way. not only for gigging but studio work too. You do what it takes to get good sound.
  15. I've never seen Linear and audio pots in a factory build like that unless it has active electronics. You can purposely add them if its something you want depending on the pedals, pickups and amps being used. Back when I was a kid just learning this stuff I used to Cannibalize old electronic gear, especially TV and Hi Fi stuff for parts. I learned early on pots were designed for different signal strengths of gain staging and substituting the wrong ones can do some nasty things. A pot attenuating a line level signal between a preamp and power amp for example are almost always linear. The signal is usually above volt and the impedance is often low so the resistive pad can be linear without sucking tone from the signal and it sounds normal to the ears. The weak output of a pickup is only a tenth of what a preamplified signal is the tapering is added to accommodate both the Haas effect and the Fletcher Munson curve of the ears as low volume levels are ramped up. You can add a bleeder cap you can further change how the volume vs tone changes as you turn down. Some pickups like Humbuckers can take a quick dip in volume going from 10 to 8 on a volume knob and loose half their volume. Dialing up the right amount of overdrive from the guitar can be very glitchy depending on the gear being used. Changing the taper can be one way of changing how gradually the drive or volume tapers down and adding a bleeder can help maintain the brightness of the signal, even when the volume is nearly off. Typically I wouldn't advise using a linear pot for pickup attenuation unless the pickups are active. What happens is the volume goes from zero to 90% when the pot is turned from 0 to 1 and the rest of the range from 1 to 10 only varies the volume by maybe 10%. That's pretty much unusable in my book. Its pretty much like using a switch to cut the volume off. The wrong pot value for a pickup can make you think the taper is wrong too. I've used 1 & 2 Meg pots on single coil pickups and they taper much like a linear pot or a pot with a bleeder cap does on a pickup. The volume can remain high till its turned nearly off then it takes a big dip at the end and practically switches off. Again, that might be just what you need for some gear. Fuzz pedals for example might benefit from this because their built in pots often ramp the gain up within a small percentage of rotation. Having an input signal that is less tapered can take advantage of that 10% change and spread its effect out over a longer rotation. The Dallas Arbiter Treble booster was another glitchy pedal designed to overdrive the first gain stage of an amp. If you used the volume on the pedal itself it would create all kinds of crackle and jumps in volume as the pot is turned due to the higher voltages passing through the pot. This is why most are set to a fixed level and set on top of the amp instead of used like a normal stomp box then the gain levels are varied using the guitar volume instead of the knob on the box. Different guitar pot tapers can change how that pedals gains up the signal and how much Frequency response it has at those levels. There are some rule of thumb formulas used when designing circuits which do have a foundation in physics for this involving impedance and gain staging, but guitar players have been breaking those rules since the first player cranked his guitar into saturation. Many of the components like pickups were built by ear instead of with a slide rule and other components like pots and amplifiers came from either the telephone or radio industries and simply adapted so what gives you high fidelity is rarely what a player wants. The player often prefers something unique or just the opposite for good clean sound which shoots holes in many of the formulas you'd normally use so my advice is find a junk guitar for $25 and use it for experimentation. make sure its something that has easy access to the electronics cavity then buy a bunch of inexpensive parts on eBay including switches, pots, caps, and pickups and go to town trying out all the different wiring possibilities. It can be a whole lot of fun and it removes the mystery surrounding allot of this stuff when you have the hands on experience actually using it.
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