MacroFab Engineering Podcast #154
MacroFab Engineering Podcast #154
The US Mint Denver produces 30 million coins a day. Denes, the tooling department manager, discusses with us how production at this scale functions.
Stephen is on the hunt for the next step in his electrical engineering career and shares the shifts in the industry and what employers are looking for.
Relay manufactures hate this one simple trick that makes your “sealed” relays last longer! Except TE connectivity who has an note about this relay feature.
Visit our Public Slack Channel and join the conversation in between episodes!
Cliff Schecht of Reclaimed Audio!
Some audio gear Cliff is working on restoring to its former glory!
Parker is an Electrical Engineer with backgrounds in Embedded System Design and Digital Signal Processing. He got his start in 2005 by hacking Nintendo consoles into portable gaming units. The following year he designed and produced an Atari 2600 video mod to allow the Atari to display a crisp, RF fuzz free picture on newer TVs. Over a thousand Atari video mods where produced by Parker from 2006 to 2011 and the mod is still made by other enthusiasts in the Atari community.
In 2006, Parker enrolled at The University of Texas at Austin as a Petroleum Engineer. After realizing electronics was his passion he switched majors in 2007 to Electrical and Computer Engineering. Following his previous background in making the Atari 2600 video mod, Parker decided to take more board layout classes and circuit design classes. Other areas of study include robotics, microcontroller theory and design, FPGA development with VHDL and Verilog, and image and signal processing with DSPs. In 2010, Parker won a Ti sponsored Launchpad programming and design contest that was held by the IEEE CS chapter at the University. Parker graduated with a BS in Electrical and Computer Engineering in the Spring of 2012.
In the Summer of 2012, Parker was hired on as an Electrical Engineer at Dynamic Perception to design and prototype new electronic products. Here, Parker learned about full product development cycles and honed his board layout skills. Seeing the difficulties in managing operations and FCC/CE compliance testing, Parker thought there had to be a better way for small electronic companies to get their product out in customer's hands.
Parker also runs the blog, longhornengineer.com, where he posts his personal projects, technical guides, and appnotes about board layout design and components.
Stephen Kraig began his electronics career by building musical oriented circuits in 2003. Stephen is an avid guitar player and, in his down time, manufactures audio electronics including guitar amplifiers, pedals, and pro audio gear. Stephen graduated with a BS in Electrical Engineering from Texas A&M University.
Special thanks to whixr over at Tymkrs for the intro and outro!
Welcome to the macro fab engineering podcast. I'm your guest Cliff Schecter.
And we are your hosts Parker Dolman.
And Steven Gregg.
This is episode 154. Cliff Schick
is an electrical engineer and spends his days rescuing vintage gear. He is the CEO and operates reclaimed audio reclaimed audio offers repair and restoration services on audio radio and test equipment from the turn of the century through the current state of the art.
Yes, sir.
So cliff, on on that? How do you go about restoring audio gear? I think that's like the big overall picture of this podcast.
Okay, so it really kinda starts, I get a piece and the first thing I do is rip it all the way apart, I want to look inside, see what's going on, knock all the dust out of it, because there's usually quite a bit of dust of stuff sitting around from 30 to 50 years and whatever.
So what's the most interesting thing you found inside of a
man that says, So
Parker just goes right for it.
I charge I will charge extra. If I open something up and I'm finding cockroach bits inside of your pots. I'm sitting there pulling them out with a pair of tweezers. And I've spent that you know, hours on and that's why it's crunchy. Yeah. Sounds like crap. Oh, well, there's actually crap in it like bass crap. Oh, I've seen the NAS and but that's where you know, I got it for five bucks. So I could deal with a little bit of bass poop and cockroach and lots of geckos and stuff like that. Yeah, I've seen some.
Okay, so you say you, you open up the open up the gear, you kind of tear it apart? Take a look at it, then what do you
do? Well, so it really depends. So the first thing I want to do, I don't necessarily rip all the boards out immediately. I just want to pull it apart and take an overall look on the inside. See if somebody else has worked on it, because a lot of this stuff has been messed with in the past by somebody. So it depends on if, if I know it's working or not as well, sometimes people send something in is working and they just want to keep it working. So it really depends unit to unit and what type of unit it is to solid state. If it's a tube thing, was it a kit? Because if it was a kit, that means somebody went in there that was maybe not so good at soldering. So kind of just evaluate what's in front of me. Am I gonna have to fix a bunch of soldering work? Or is the soldering good, but there's parts that are known to fail? Why is it here pretty much. So I'll go through and look at like, what type of parts are using, try to go through a date things like the capacitors, they'll have date codes on them, the parts and things like that. And then let's say on like an old Marantz or something that's a classic unit, I kind of know exactly what needs to get done in those every time I get one just because they're about the same for model the model unless you're there's certain features or whatever but ignoring that just the absence such tend to kind of just need the same stuff.
brand specific equipment has like a certain thing that usually goes wrong with them.
Exactly like Mirantis will have certain transistors and caps that I know I just automatically I'm going to change them out. Making Tosh I know on like certain their their power amps with the auto formers, I'm going to just rebuild the driver cards completely. There's Yeah, it really depends on the units and the brand. But then some brands are known for using stairs, the transistor, the they look like little outhouses. The leads were silver, silver coated the silver oxidizes, that oxidation works his way into the plastic body and causes them to fail at the barbed wire or you know the barbed wire to the interface. And there'll be intermittent, there'll be noisy, the gain will go to crap. There's all sorts of problems you run into regardless, they're not working and they need to go in put in better parts. And so
how did you actually on that particular that's, that's really specific there? How did you learn about that one?
Well look at an old transistor and why are the legs black when they should be silver? Like it's you know, acid. So it's just you know, reading around, a lot of this information is available online. And on my end, I do have a master's degree in electrical engineering. So I spent seven years on top of my electronics hobby before that, like just on top of the ad experience. The info is really out there audio karma, there's kind of learning who you can trust as far as the info and learning kind of how to take what you've read and then verify it and apply it and things like that. That's where my technical knowledge really comes in handy. Where I don't get caught up on things that other people may get caught up on what type of diode I'm using or something like that. Just throw it in there. It's gonna work. Well what about Nope, it's gonna work I like when I'm coaching other people. I'm like, No, let's do it already. That's good. I've done it, do it, it's good. Hey, it really depends.
Yeah, and I'm sure working with the Hi Fi audio community, they're very particular about every little detail. So So you kind of have to either train or coach or kind of go along with it, right?
Every customer is different. And that's kind of another thing, I try to be very personable with everybody. I'll get those customers that a lot of people are, you know, they'll contact me trying to commission something because I know I have shelves filled with gear. And don't say I only want to make condition stuff that I know only one person owned, and I'll show them what I have. That's that type of equipment and see if we have something that's a good fit for them. Or if it's, sometimes I'll get those guys that they want the I call it like mechanic specials, where like, it's something I went through and restored it, it ain't pretty, but dang, it sounds good. You know, stick it in your garage, and it's good to go, you can beat it up and not have to think twice about it. And you're not paying, let's say it's like a huge pioneer, instead of it being $24, it'll be 1200 bucks or 1000 bucks, you know, I'll get my time, I'll get my money out of it for the time I put in. I don't get that extra added value, I guess of it being the crazy mate condition. But I probably didn't pay much for it either. If it's a roasted out unit that I still put time into.
So on these units, like is it easier? This is another really big wide question, I guess. Is it easier to work on like newer equipment or older equipment?
It's more who designed it? And did they make it to be worked on. I personally actually like working on that old point to point vacuum tube audio gear where like, everything's kind of a big, it's spread out, you can I kind of like open it up and read it like a book where I can see where the power supply is kind of go through see all the different sections. This is your RF section, audio phase, inverter, power tube stuff. And it's sort of funny, I keep saying it's one of those things where it's brands was spread specific, you know, certain brands like fishers, I just I love working with Fisher, old Fisher, tube amps and stuff like that, because they're just built so well. They're made to be worked on their spaceships inside, they leave you room on top of what they did to do additional work for you know, extra power supply caps underneath the bottom, I will a lot of times I will to keep the original look, I will not remove the original can capacitors, I'll just clip them out on the inside. And then you can you can use like e6 1000s are really good industrial glue to glue them in and you install turret boards, whatever you need to do to secure it in properly. But why red new caps discreetly underneath that versus trying to replace the can cap and you kind of lose the look. And they have date codes on them and things that keep an error appropriate? I guess. So that's a part of maintaining the look versus the versus the quality or you know the reliability thing?
Yeah, have you ever seen the picture of Have you ever tried with like the, they got the capacitor and then put new guts inside that's a smaller capacitor,
I've done it some it's kind of a time consuming process versus just clipping them out and installing them underneath with it really depends on some units, you almost have to do it. But at that point, I might just put in new or caps. But the reason to do that is if you have something where it has unusual values, like a 4040 4500 micro farad or something like you can't really find that off the shelf. These days, they do make new canned caps, but they may not have some of the oddball value. So there are times when you have to do something like that. But a lot of times I can stick that 500 micro farad cap, the new caps are so much smaller, you can just sneak it on in there and that chassis, so much room with this old tube stuff for fitting in. But that's kind of the funny difference between working on the tube stuff versus a solid state with solid state it's remove old cap, put a new cap with the tube stuff, you have a lot more freedom and like it's a lot more I guess off the cuff of us your you just kind of approach each section at a time.
Actually, so that brings up another question that that I've been I've had in the past or I've been presented with is Okay, so with the can caps, you know, sometimes they have like a 37 micro farad or you know something where it's just like, Well, okay, I'm never getting that. So so in that case, would you try to parallel caps? Would you try to put a 35 or maybe go to a 47? Or do you do substitutes, like how do you approach a situation like that?
It's very situational. If it's on something like a speaker or it's going at a crossover and you want to get them as match as closely as possible. I'll actually go in and replace that Not only the film caps with the equivalent value, and actually you will keep parallel caps or whatever to get, if it was 4.7 micro farad, you can parallel up to get them as close as possible that and change the resistor to really get that match closely. But or a lot of times, you can just round it up or round it down a little bit. If it's determining something like a cut off frequency, then you maybe want to be a little more careful about choosing it. But there's usually a bit of leeway in that anyways. Like say it's on the input of a, an amplifier stage, you can maybe bump it up just a hair, and usually not run into anything like you're introducing a crazy phase. A bunch of additional phasing issues or something that causing it to go an oscillation or something crazy like that.
Well, in in capacitors, even capacitors nowadays are like plus minus 20% of their value.
A lot of times they are even the higher quality parts or use, they'll be plus minus five 10%. So it's really like, people tend to hyper focus on this stuff. And I've noticed that people that will focus on that stuff more maybe aren't so technically minded. So that's something that's tangible that they can grab on to and focus on a little bit more, I guess. It's the same with like, Why do somebody, a lot of these old fissures I sell that people just adore the sound? And I love them, too. They are just filled with ceramic caps. And what have you read online ceramic caps are horrible for the audio path, and you can't have man they're distortion and oh my god, they're microphonic that no,
that's actually funny. They are. We had a previous podcast where we did the DAC testing. And people liked the DAC that had ceramic caps in it. And the audio path.
Nice. Yep. There's not really a huge issue with them. If you can go through and you know, if you're sitting there flicking them, and they're dinging at you. Yeah, you probably should change them out. Because you're gonna hear that same with the tubes, though, like a tube amp.
You know, it's funny in multiple tube amps. Throughout the years, I have I have tried to, you know, sniff the audio fairy dust. And I put silver mica is it for the low valued caps, I tried it out. And in every amp I've ever built that had silver mine, because I've never been pleased with it. And every every amp I've not used silver Mike has had been my better ones. Yeah, that's just personal.
Exactly. I can't sit well, exactly. Like I can't say, I dislike them. But I'm not gonna say like, I have to use silver market, it's not part of my sound. What I tell people a lot of times is these caps are typically they're nested in feedback circuits, where it's gonna get it's gonna get, you know, in a negative feedback circuit, it's gonna get divided out by the amount of gain that's in the feedback loop and all that anyways, like, so. If there's a gain of 100, the difference is already 100x. Less, just, I don't know, off. It's just from the start. I just really personally have not heard or had people complain about like, I've never sent out a unit that I restored and had somebody say, Hey, man, this thing sounds worse than when it came in. And I've read about that. And it's something I've truly been nervous about in the past, especially with certain customers, the ones that are very particular. But I give them my honest opinion that exactly what I told you guys, I've never had anybody like say, Hey, man, my Miranda says his sound is good. After you went through it. Usually you're like, holy crap, man. It sounds great. Thank you very much. The best thing I can the best thing for me is when I don't hear back from them other than they want something else worked on. Because that way I know it's done. It's good. And
you don't have someone calling you up and going, you shouldn't use that 3.33 repeating a course micro farad capacitor.
Exactly. Yeah, they can hear the trust.
Yeah, those audio files. Well, it's I deal with a decent amount of audiophile crowd too. And I don't have I'm not having issues with those guys. As far as like our opinions clashing I try it's almost like getting into a religious discussion. Like, I will respect your opinion, you respect mine. And we're everything's copacetic. And we can even talk about the differences and not argue about it and just respect your opinion. If you feel like that $10,000 power cable makes a difference. And I'm happy for you. I don't feel like it's Yeah, exactly. Literally.
I so so I actually I had a customer once that I did some work for and he he showed me his setup, which he had spent
there was many zeros behind the numbers that he had spent on this his system, and he had actually paid the power company to run a separate line and an individual power pole. For one room in his house for his theater room. He had he had a separate electric bill for his audio room. And and it was just the insanity that he wants. It's
just baller status at that point. You're just doing it to do it like you he doesn't have a lift. It's like having a lifted truck. He doesn't Hear the difference, but he could tell people he does. It sounds cool to tell people Yeah, I got my own law like, yeah, that sounds amazing. I bet it's better makes a difference. Like the dedication was impressive, that's for sure. It's I read about them doing that in Japan, you were just read about some crazy stuff. And I have dealt with that crazy. But then it's like, one of my customers. He had some audio cables that were like RCA cables, but they had oil in them or something. And one of the cables busted in the oil, gotten his amp, and he thought it messed up his amp. And I was like, Well, if he just had dry cables, it wouldn't have been an issue. The hell you deal with oilfield cables. He was like, Well, I swear I heard the difference. A lot of dampens audio signal. I don't hear that diff.
That sounds really greasy. Yeah,
they'll say like they don't hear the difference right away that you'll hear the difference over time. And I mean, to me, it's a lot of like hearing what you want to hear the psycho acoustic effect that I don't know if To each their own is how I like to put it, I don't want to tell people they're wrong. It's like even even with my like sales pitch, I try not to be like a high pressure salesman, because I know. At this point, this stuff's gotten pretty collectible. And it's going to sell regardless. So I try to let people choose what they want versus forcing any one thing on them unless I have something I really want moved out, then I'll discount it, you know, Hey, man, you should really buy this. It's a good unit. I know it doesn't say Marantz on it, but it'll kick your Mirantis as
well. Okay, so So back to the repair side, I got a question for you that I think it's, it's a potentially a difficult one, or maybe an easy one. So when you open up any piece of gear doesn't have to be an app. How do you know what you want to do to it and what you want to leave alone? I guess the leave alone part is the part where it's like, that's the hard one to determine, like, how do I how do you say, oh, that capacitor is fine. I'm not going to replace that.
Well, and that's where I go through and instead of doing picky, choosy, pulling apart out measuring it, okay, yeah, here's the thing with that is, for the time it takes me to remove one capacitor, test it, reinstall it, I have a Hakko the FR 300 D soldering gun. I've already soldered the entire board. By the time it takes me to test that one cap. So just on my end for, I guess, brevity sake to try to just get it and get out. I know what it's probably going to need. And instead of guessing what's probably gone wrong, I just change. And I guess this is a bit of experience and rating and just some knowing but knowing that like okay, the electrolytic in the tan lumps typically are going bad for different reasons. But so like if I see those, and if it's something that somebody sent in for full restoration, I'm just going to change them, not really think about it. And then I'll go through and look at like the transistor types and see if there's ones that are all my, my, my naughty list of you know, known troublemakers or certain diode types that are just no troublemakers, they drift they fail. It doesn't even necessarily matter what mechanism was causing them to fail just knowing that they suck, and they need to go pretty much is it like, it's good to know the why. On my end, I want to I want to be technically sound and know why it's failing. But it doesn't necessarily matter. Sometimes it's more as long as you know that it's failing and or it has potential to fail. It's you know, a known troublemaker, as I like to call it then I'll just go ahead and change them out. Especially the I don't know, there's like really notorious ones. And then there's more discretionary stuff where like, if somebody's paying the bigger bucks, they want me to just go all out versus scale it back and save a little bit. Well, maybe I don't touch as much as the silicone or maybe I don't touch a whole section I just DeOxit and fader lube and make sure it sounds good is performing up to spec and then we read our fader lube. So fader lube is. Okay, so this is actually kind of a big thing you'll see a lot of people in like forums and stuff like that the Bekaa by receiver doesn't sound right and the first thing everybody says is oh DeOxit hit it with DeOxit you don't want to just put DeOxit in your pots. There's a especially on the really early ones, the carbon ones because there's a lubricant in there as well. And when you do just fade or do you do just DeOxit it actually flushes out that
you're talking about removing the oxidation on the carbon wipes inside a potentiometer.
No, I'm talking about this is actually on a potentiometer the track you have your wiper and then the track that there is the carpet. Yeah, that on the vintage pots if you use just the opposite. It washes out there's a lubrication on there as well and it washes that away. And then you have metal straight on on the carpet and it wears it out way quicker. So fader lube actually has an additional lubricant in there. That is what you're replenishing. What the DeOxit washes out, it's actually the additional lubricate you need. So you don't wear out your tracks too quickly. That's fader level,
that alone will make things come back alive. It
literally Yeah, just DeOxit like I call it, it's kind of fun, because I don't really do much of it anymore. But occasionally I get in a lower end unit, it's not really worth it to do a full restoration. I do the I call it the spray and pray where he just kind of spray it out, clean it out, and then pray that it works.
So here's a here's a question for you. Well, actually, I wanted to I kind of wanted to touch on on what you were just talking about there. I think you've kind of like explained it in a long way. Really what makes your job and what what you do, I guess, I guess people don't really have a full understanding in a way for what you do. Because it's just like, oh, I bring it to the guy. He's like an auto mechanic. He just fixes it. He just follows the manual. And, and it's not that way. And in fact, you kind of discussed it a lot there. You mentioned, there's a lot of discretion. There's a lot of kind of, in a way secrets that you know, a lot of things about, hey, this transistor gets replaced, blah, blah, blah. So there's not a whole lot it seems like that there's an instruction manual for everything. There's so much that you've picked up along the way. Right?
Exactly. It's kind of a, it's almost a learn as you go type of job. And I keep saying it, every unit is different, every brand is different. Their engineers all had different ideas on how things should be done. And things change from era to era, obviously, from 2d to early solid state and then early solid state to the 70s stuff. And then how they approach things in the 80s with the ultra high speed amps and higher power. And every one of those kind of has to get approached differently with how you restore them. How much work they're actually going to need. It's yeah, it's very, it really depends on you know, every and then how was the unit stored? How was it taken care of was it maintained in the past? There's just so many variations. And that's actually what makes the job kind of interesting. In the end is every day is different. Every unit is different. Even after I go through and do what I know Samaranch needs, I may have to trace out a couple of little issues that the owner didn't tell me about or I didn't know about or. And then there's the actual cosmetic side of things, making things look as do as you can. I've learned a lot of weird little things like vinegar and clear and digitization don't work or sorry. Ammonia and clear entities ation don't really agree very well like it'll kind of cause it to look smeared and definitely like on old, any old glass styles. This is like a rite of passage for taxes. If you get like an old Fisher dial wet, and then you wipe it off, it'll actually completely wipe off the logos because it's old, like waterslide decals. Oh my god old Marantz is an old Macintosh and Fisher units and stuff. If you see that glass, you just use your breath. And use like a shirt. That's all you need. You don't want anything more than that. Or you will come right just wreck that. Yeah, exactly. I've done it once everybody has done it once. And then hopefully that's
what Well, here's a question for you. I want your opinion on something. Parker and I talked about this, gosh, a few months ago. So I have an old Hickok power supply. It's a high voltage regulated power supply zero to 400 volt with with a handful of extra little gizmos in there too. So I cracked open the power supply because I was thinking hey, maybe I'll do some restoration on it. And frankly, it looks like a mess inside. And I didn't really want to spend all that time on there. Now here's the thing, it has like six or seven cap cans big ones. 500 micro farad 40 volt kind of guy. So they're not necessarily super common stuff. And they're puffy. So they've obviously had some age on them. And they're they're old. Now here's the thing, the power supply fires up, it runs great. I don't detect any noise on it or anything. So in your opinion, should I do anything or should I just go until it fails?
Well the problem the thing that the thing that worries me about doing something like that is what it fails it can't fail pretty fantastically like have you ever seen what those can caps look like when they really blow their guts like oh, I've made it kind of sucks. Like when when you when you have to actually clean up that mess or whatever. So it really depends if it's something that I'm gonna put into regular use in my Shop. It really depends like so my tube testers are still mostly all original and they're working fine. Or they kind of came as is I know they're calibrated previously. So I will use, I kind of use them as a not a, like the numbers that has given me aren't the calibrate, I need to go have in the calibrated, but I know they're about good enough, I'll compare them to no good twos versus what it's given me for what I'm testing and things like that. And it's definitely good enough, because then I'll also test them in circuit and make sure everything's balancing out properly. But it really depends on what you want to do with it. If you're going to use it regularly and you need it to be reliable, it's probably not that hard to find, you just go with like a 470, micro farad 50 volt cap, or you could bump it up to four set, or you go to 1000 micro farad 63 volt. And the reason to step it up that extra 13 volts is because it was probably designed to run off of 110 to 117. And then modern wall voltages tend to be a lot higher like 123 125. So after the rectifiers and everything, you'll actually have a little bump in all your voltages. And so gives you a little more headroom on some of the caps. And I actually like on some of the all the power supplies and stuff like that. And a lot of these units, I'll do that I'll step it up, what extra rating for the voltage, maybe for the capacitance and like a power supply, you actually have to be kind of careful about that. If you go from say, a 10, micro farad cap to you know, 1000 micro farad cap, then the inrush current could be enough to say blow out the diode that's feeding that rectifier circuit. You know, there's things that I'll see people doing like that where they don't necessarily, you can tell they don't necessarily know what they're doing. They're just going in and trying to make it work again, and
they don't understand the consequences of their actions. of
re engineering. Yeah,
right. Right. Yeah, if there's a small value cap in there, there's typically a reason why it's a small world small Earth value cap. You can't just keep going up and up and up.
Yeah, exactly.
I on that, Steven, I would, I wouldn't really care too much about the mess, I guess those capacitors would make, I'd more care about like, whatever the power supply was currently powering when it decided to eat the dust
and explode. Yeah, exactly. Well,
you know, I mean, the thing is, most of the stuff that I would power with 400 volts could probably take a blast anyway. I'm not too worried about that.
Now, like I but but I just know from experience, because I have done restoration on things of that sort. I know that it would be many, many hours of time, you know, tracing out things pulling, pulling all the wiring, because the wiring is awful inside of this power supply. It's just like, do I feel like devoting the 10 to 12 hours I know it's going to take to just replace, you know, a handful of caps? Or do I just keep going and so far, it's not it's certainly not an everyday use device. For me, it's like a once a month, or every other month kind of thing. So I don't know, it's one of those things. I'm just like, I'm not sure if I should actually do
it kind of you'll probably like turn it on one day and see it has too much ripple or something. That's the type of thing where I'll just make sure it's fused properly. Make sure the power cord is not crunchy. And just use the dang thing until you know until it pops and then fix it as it breaks. That's you know, especially if it's personal thing I've got a tube amps and stuff I use where almost all the caps are original and I reformed them I have a I have a meter that will tell me it tells you dissipation factor which is related to ESR. It'll tell you the capacitance. And if I know those two are okay. I mean, why not use it? Oh, you can also physically on these old cam caps. A lot of times you can physically see if the seals okay. I haven't found that they need like that crazy reforming process where you bring it up on the very act slowly over the course or whatever if the seals are okay, and I tend to use the thermistors or lightbulb limit or something to where it kind of slowly ramps it up. But over the course of a few seconds or something not you don't have to go this 1020 minutes. Usually they're good or they're not good. They're not
gonna explain this reforming process because I'm a digital electronics engineer. So like, that sounds completely foreign to me. Okay, slowly ramping stuff up,
get ready for the wank.
Well, so forming capacitors has to do with you have an aluminum layer. It's like an aluminum foil and then you have this electrolyte gel inside of them and then the other. The other plate Yeah, the other roll of aluminum foil. That's your capacitor, but the actual insulation is it from that electrolyte gel. It's from the layer of aluminum oxide that forms from that electrolyte gel and that's what gives you your capacitance. And that's what depletes over time and what you essentially need to do What's you're trying to reform by bringing it up slowly? Sorry, my dad just he's one of the helpers. I'm doing a video a blog. Sorry. He's actually a W as well, he does. He has his own bed chair he gets to play when he does a lot of RF stuff for me. hellesdon keeps the radios working when I get the cool head scratchers. And he does a lot of old. He likes to transistor radios and stuff, the early transistor radios. They're, they're a lot of fun to get going. And they're kind of like, you can usually knock them out in an hour type projects. And there's actually I don't know if you've ever looked there's a really big collector's market for those. A lot of this stuff now really, stuff that people had when they were kids aged, it resonates. You know, let's call it a ball, the Soulja, but then having it work as well as just the extra cool factor on top there are still am radio stations. Here where I am now I don't really have one that I listened to too much. But when I was in Lubbock, they had an old country station that I listened to almost nightly because it was and you put it on an old tube radio, and it just has the sound kind of has the it's just it was great. And they played a lot of old Hank Williams and stuff like that it was just perfect. So yeah, there's definitely that like, I mean, even with the whole vinyl thing, like I can play an mp3, or a WAV or whatever, a high quality audio file, and it sounds great. And then I can take the same thing that was it was recorded saying the 60s or 70s 70s, where they were carefully crafting these albums and then carefully mastering them so that everything was perfect. I do actually sometimes think that the vinyl sounds better sometimes the it really depends on who mastered it, whatnot. Kind of hopped on a tangent there.
It there's so many throughout the whole process of creating music, there's so many knobs that people are turning, it's really hard to make it work across the board. So yeah, you know, it's one of those things where, who you right, whoever mastered a vinyl may have done it in a way that you really like it. Or it may work really well with whatever circuit you're putting it through.
Yeah, exactly. Yeah, that's where like, I'll have certain from my system, I definitely have certain demo tracks that just make it just makes it saying it sounds so good. Like you'll watch people get goosebumps when they hear it. Like that's what you're going for. Like that's when you know they're feeling it like you could see it. Yeah. So.
So when you're when you're taking these units apart and starting to replace the parts in them, When do you go, Okay, I'm going to turn like turn this thing on for the first time. Because if you let's say you bought something off like eBay for a buck. And it says broken, you notice a little plug that thing in right away, right?
That's where I we were talking about the very beginning, the very first thing I do is, when I buy something, is I pull it apart, I want to see what's inside. And so I'll go through and I'll evaluate it on something like a solid state amp, I'll just go through it board by board, each board gets treated, and then I go into the service manual, I look up, if any of those boards needs certain adjustments on your power amps, you typically need to set the bias, you bring it you set the bias to the minimum. And then you set the DC offset to what looks like centered. And then essentially, all you need is a variac and a light bulb limiter. You don't need the variac. But it's kind of good to kind of bring it up slowly. And my variac also has a watt meter. So I could see if I'm drawing too much current right away or something like that.
And real quick, for our listeners who are not super aware, can you can you explain what a light bulb limiter is? Yeah,
I was I was about to get into that. So that's one of the two things that is really kind of saving your butt on any solid state gear, the light bulb limiter is a light bulb that goes in line with the power so that as you're bringing it up, a light bulb has a negative resistance so that as more current gets goes through the roof, it starts as it gets brighter and brighter, the resistance goes up. And so it's only you get to a certain point before it's just at. Essentially, if the answer is draw too much current, the light bulb turns on. And you kind of want to size a light bulb so that usually like 50 watts for smaller amp 200 watts for larger, do it for a larger amp. But it's a relatively simple way to see if you're drawing too much current and then when you're setting say the bias if you did replace the old trim pots, which I don't always do, some people always do. A lot of times you can clean them the the trim pots that you would use to set the bias on a power amplifier. Well if that was like skipped out momentarily from dirt or something like that, then in some circuits that means the power amp just goes full power right away. And you'll see that light bulb limiter fire on like a rocket hopefully, before anything gets damaged. If you don't have that in there, then it's just going full current until something blows opes a lot of times it's not just a fuse, it's transistors and emitter resistor. errors. And, you know, if it's big enough, and things start really burning out good, you get craters on the boards, and it prevents things like that from happening. Oh, yeah. But that's also why you're using the very act to bring it up slowly. And yeah. And then there's certain gear that you can't use a variac. On some bigger power amps will use primary site switching like the cover amps, they'll actually do a, they'll only have it on for a portion of the site input sine wave for the, you know, from the wall. And they do that. So they could use a smaller power transformer to get the same wattage, they only turn it on a full time as it's needed to actually have a circuit that looks ahead, looks ahead, and it sees what the amp is doing. And if it's a high demand, high demand moment in the peak in the song, then they'll turn on the additional supply and give you more of a sine wave too. Obviously, you get more power, they'll turn on additional supplies that's like, you know, Class A Class G switching amps and things like that.
That some parents that control? Yeah,
that's something that where you don't really want to use a lot of times, I'll tell you don't use a variac. Unless you have the Triax. On the input side, you have to show it off the track before you can use the variac to troubleshoot the second like everything after the transformer essentially. And that's not just a carver specific issue, Yamaha did it a few amps, and there's a few other companies that have done that kind of thing. It's kind of something you don't see so much anymore is it's actually a budget saving thing and not really a selling point anymore.
Yeah, who wants a small transformer on the top of their amp? Right?
But it's how Carver got so much power in those tiny rack units. Like it's cool what he accomplished with what he did, but there's definitely some there's some bad that goes with the good with that circuit? Not my not my favorite thing he did. But I can appreciate the technical aspects of it.
So is there any like, I think we talked about a couple of the myths of audio gear, but is there any, like major myths that you ever debunked?
Um, I don't really at this point, I've kind of spent the time I built a lot of like guitar amps and stuff like that I spent a lot of time cloning vintage Fender guitar amps. And when I was doing that, I was using a lot of the error, correct parts, error, correct resistors, the capacitors and stuff like that. And really, what I'm finding is I still have a lot of those apps and 10 years later, they all have a bunch of problems. Now the caps are leaking. Just things that you don't want to happen are starting to happen, I'm having to go through and like, redo work I did, Ted, this is when I was learning how to build a tube amp and trying to make it I was using Parkside at the time or new old stock. But you know, 10 years down the road, it's really on a couple of the apps that I was using personally, like, I personally have worn some of those caps out. So I tend to stay away from like, I'm okay with carbon copy resistors, there's actually a measurable second harmonic distortion that they introduce, if you have enough. If you have enough voltage across them, a voltage drop across them, they actually introduce a measurable distortion that will slightly sweeten the sound, it is an appreciable difference that you will hear if you build an amp with carbon film versus carbon copy resistors. Like all throughout the amp, they'll probably be noisier with the carbon copy as well. But you know, you take the good with the bad in that case. But I've gotten away from using like the old film caps and things like that. I also don't go for the ultra handmade boutique audio file caps, that hand roll. I don't want to pay 50 to $80 per cat to, you know, for the bragging rights of doing so when I personally just did not hearing a big difference. I don't measure a difference. And that's really the thing. Can you measure a difference I have inside of a huge rack of audio tester over here distortion analyzers, HP Agilent, all the good stuff. I'm just not seeing the difference on them. I don't hear the difference. I'm not having customers complain that they're hearing the difference. All I'm hearing all I'm getting told is that, hey, it sounds good. It's still working. If they're happy, and I'm happy, then, you know. I don't know I think a lot of people I think I said it earlier it I see a lot of people that aren't as technically minded to hyper focusing on those types of things like what brand is on the cap versus what value is in the circuit. They'll sit there and swap the same value but different brands expecting you know, some kind of a difference in the sound. Well, I'm just going to redesign the circuit because I can see why it sounds the way like you'll tell me Well it sounds a little dark. I'm not going to change the same value cap out for the same value to make it brighter. I'm going to change the value or modify the circuit somehow to brighten it up. They'll talk about like the flavor differences these days are talking about like its food like palpable stages and the flavor of this cap and This is smooth and this is spicy. It's just like this. I have to personally use these words to describe audio circuits. I've learned how to talk the language. But it's kind of like from like, from a technical standpoint, it's kind of shameful that I can't use the like technical jargon, I have to use the like, yeah, I have to use words that people can understand. You know, they don't necessarily,
you know, it's funny I was I was watching a video just the other day where somebody was swapping out different types of caps on different dielectrics, basically. And they were showing like, oh, they were saying, hey, this sounds different because of XYZ. Although the funny thing was, the caps that this person was swapping out had a tolerance of 20%. So you're hearing the tolerance, the value shift between caps, not really the caps themselves. Now, if you could measure them, and get, you know, point 1% and then swap them out, that'd be a little bit better of a test. If he asked me,
well, even then, I've heard so many stories of these audiophile guys, and not just I don't want to just pick on them. I've seen it in the guitar community, the guitar pedal community, where the one I remember specifically was, they did a test with some audiophile guys. And they had you know, audiophile speaker cable versus a coat hangers or something, you know, if thick metal but nothing special. And, or maybe it was lamp cord. And they did a blind AV test. And I don't remember the exact number, but it was like, they either couldn't tell a difference between one cable and the other, or they actually were choosing the crappier cable over the better cable. So there's just a lot of that, like, psycho acoustic effect, and people hear what they want to hear they hear what they like, if you spent $500, but they're telling you this $1,000 cable sounds better? Are you going to hear? You know, the, the failures of this $500? Cable? Are you going to hear the differences? When you spend the extra 500 bucks with $1,000? Cable? Are you really going to hear a difference? Why is there a difference in the cable? I've just I think you'll do what makes you happy? Essentially, yes. And that's kind of where like, you know, it's almost like talking religion or politics, you know, you just, it's, it's almost an opinion type thing at certain point, like, respect other people's opinions and do what you're gonna do. And that's kind of how I try to approach it at least. And if a customer wants me to use audiophile grade caps, if they're providing them, I'll use whatever they want that whatever they want me to use, if they want me to use my parts that I know are gonna sound fine. And they're, you know, 105 degrees C rated parts. 3000 5000 10,000 hour rated caps made by the Chicago Panasonic this stuff, they this is like, the good stuff that
they make quantifiable quality.
Exactly. And the other thing is source from a reliable source Mouser and DigiKey. Where I know it's not coming from some factory in China. Are they reliable over any kind of goofy? This? I know they're coming from manufacturer, Mauser me. There's no question. I don't buy parts. Very, very rarely buy anything off of parts wise off eBay. There's just too much too many fakes out there. In general, that's actually a big thing that you run into on eBay and such as a lot of fakes out there. And sometimes it's done dangerously where they'll take say, a DECA 22, micro farad 400 volt cap, and they'll spray stuff it into like a new looking cap, and it'll say like 47 micro farad 500 volts. What happens if we put 500 volts on a formidable cap? Well, it's gonna blow up at some point. And it's actually I've seen it on you know, forums and stuff like that, that guitar amp guys that are buying their caps bulk on eBay and buying them in the ass. And I mean, to me, a lot of times, you can actually tell when they're fake, they'll have things that you just don't see on other parts. Like there'll be cribbed on both sides, or just it really depends, but I've just brands
legit cap for real.
Yeah. Yeah, you'll see a lot of people they'll put not even them but the actual like the big manufacturers will put like the audio grade caps and stuff like that. And
Fine, go. Yeah,
they don't really explain really what the differences are between using like, what's the ones that use silk impregnated something versus whatever I mean, Teflon is as good as it's gonna get like if you want to hear just absolutely zero influence from the cap and your circuit use a Teflon cap. It's also probably one of the most expensive technologies but don't know this. I tried to kind of stray away from the video electronics and just do what I know is going to be reliable in I guess figuring out your formula for success for Hearing out what brands you like what? And there's a lot of like, you can research it online, you like what's reliable, what's failing for a lot of these guys readily share information online. So the info is really out there if you know where to look and who to ask. And those guys really aren't that hard to find. I mean, there's plenty of guys like me, as well as me on Facebook and the forums and stuff, sharing tips and tricks and you know, people private message me daily asking me little questions here and there. And I've kind of had to start backing off because it'll start getting too time consuming. But if I can, they'll tell me a problem. I'll tell them right away, like, Yeah, it sounds like your power supplies going out. Like somebody says, hey, both my channels have hum, well, if it's both channels, it's probably in the power supply. There's things that's just higher level, you know, kind of any amp is going to have the same problem. If the power supply is messed up, well, it's probably going to have hub or bus or some sort of an issue.
So I got one more question. And so let's say you open up the amp, or open up a piece of hardware. And there's a part that's obviously damaged, but it's so damaged, you have no idea what it is, like so you know, what's like a resistor, but like all the color bands are vaporized off of it. How do you go about fixing that kind of thing?
Well, there's, I kind of call it using your like context, who's using what's around the circuit? To figure out what does it imply that that resistors? Should be? Is it in a spot where it's going to be high power? And then is it going to be a low value or high value and then event like created the board? You've lost any designators? You just can't tell what goes in there past a certain point, it's just DOA. Replace the board have? A lot of times it does. It's not not getting to that situation. It's find the schematic figure out what went and why it went and then you can build up around what failed. And it really depends. It's one of those like, it's situational. You know, every app is different. And some things just blew up so bad that and it's not well documented. You don't have schematics available, they use proprietary parts. There's a lot of those Yamaha had those V FETs. They use that. Yeah, I think that the V FETs, that they used in some of the some of their 80s and stuff like that, where if they go, they just haven't made it, but 3040 years.
So you kind of just it just goes into the landfill, then.
Yeah, or you sell it as part of now we'll pull parts off to make another one mint or something like that. It really depends. But that's where it's my job to know which units are notorious for having unobtainium parts and things like that just kind of avoiding that stuff, or buying it working. And then it's my job during the restoration and make sure it stays working. And I don't blow up anything that I can't replace.
I'm taking your MOSFETs. So what what made V vets special? I've never heard of those.
I have to even Steven
i this first I've heard of a V fit.
V FET. Magical amplifier. So you'll hear people describe them. I think the reason is they they kind of distort like a trial. So they have kind of a magical set of magical There you go. Electronics, now they have kind of a tube like sound, I guess, if you will. The problem, the problem with those facets that are just completely out obtaining at this point, and
yeah, they I'm looking at, I'm looking at a PDF that shows their curves, they they look very Triaud like, yeah,
exactly. So they have a very certain way of distorting, which is great as far as Okay, yeah, you found exactly what I was looking for, then they, they have a nice sound, they just haven't made them in 40 years. So they're a little hard to replace at this point. And if they're blown up, you're kind of either find something that you can donate amount of well, and the other problem is because they're FETs, you have to match and by their IDSS. And so you have to buy like 100 of them, you know, a couple of good pairs, so you know, so there's just kind of logistical issues with working on it too. It's not that easy to find matching vets out of you know, the, they're just all over the place from the manufacturer, like really all over the place. So to find a set to where not only matching but they match within a certain current range. You gotta buy quite a few
of cool. Steven, Steven, do you have anything else?
You know, what I would like to hear is how people can get in contact with you or find out more about you.
Oh, well. The best way to do it is either through my Facebook page, a lot of people tend to just add me to my personal Facebook page. But if you look up But it's facebook.com forward slash reclaimed vintage audio, or I mean that's really the easiest way to find me currently I need to get a website up still. I'll hopefully have that up soon and then I have a reverb.com forward slash shop forward slash reclaimed audio is where I post my restored vintage audio gear and whatnot. At least the chair units that aren't getting dumped on eBay the stuff that I've really you know, I put all my heart and soul into that's the stuff that goes on reverb and then stuff I'm not going to fix that just goes on eBay for parts for other people. I try not to throw anything out. I guess that goes with the reclaimed part of my name.
So thank you Cliff for coming onto our podcast. And
thank you guys so much for having me on. This was a lot of fun.
I'm sure I'm sure we could go on for another few hours but
I know we kept it right. I'm glad we did too. Because you start getting into the technical aspects one I could sound like an idiot if I'm not well researched and know what I'm talking about and to like you just said you can go on for hours and hours.
Well, thanks a lot. Would you like to sign us out?
I'm sure thing that was the macro fab engineering podcast. I was a guest Cliff scheck
and we were your hosts Parker Dolman. And Steven Craig See you later guys.
Take it easy
Thank you. Yes, you our listener for downloading our show. If you have a cool idea, project or topic, or vintage audio gear or test equipment that you want Steven and I to know about? Tweet us at Mac fab at Longhorn engineer or at analog E and G or emails that podcast at Mac fab.com Yes, a real person looks at that inbox. Also check out our Slack channel. If you're not subscribed to the podcast yet, click that subscribe button. That way you get the latest map episode right when it releases and please review us wherever you listen, as it helps the show stay visible and helps new listeners find us