I inherited my Dad's OHMITE container with resistors when he passed in 2014. I have it on one of my shelves in my office. He worked at Packard Bell when they made TVs and Stereos back in the 1950s and 60s. I look at the old container and remember sorting through coffee cans full of resistors salvaged from defective products. Good times.
I’ve learned more about fixing my amps from your videos than all other fix it videos on TH-cam. I’m buying a shirt as a thank you. You make perfect videos, you explain things in detail and how I can understand
A great explanation Colleen. An old ham radio trick was to trim the value of carbon comp resistors by cutting into it with a hacksaw, the deeper the cut the higher the value. Carbon comp resistors are still available from Mouser and other wholesalers, I still use them for energy absorbers across rectifier diodes (in series with a capacitor).
This was excellent and I hope the “101” series becomes a continuing thing. I started watching your channel and others others because I love vintage equipment for the objects they are and what they do, but I have no clue about electronics. If you could do a very basic “this is how a tube amp works” video I would love it. I’d probably be the only one of your viewers to want it, but can’t hurt to ask 😀
Thank you for an informative video Colleen, as a child, I loved the old school striped resistors and would take things apart to see all the components.
Years ago I had bought a vintage keyboard (hohner pianet), which quickly started making some nasty cracking noises (the type of noise you described). I thought it was some faulty germanium transistor, so I changed them all. It did nothing. Then I also changed a few other stuff. Again, nothing. The old guy at the electronic shop told me resistors can't really go wrong, so I didn't bother changing them. I thought it was about the pickups or transformer, or something. So I finally gave up and sold my noisy vintage keyboard, for like... almost nothing. Now I realize it was about the carbon resistors. If only someone had told me about this at the time ! 😭
So good. Absolutely spot on, accurate, and informative. It is so good to get away from the baloney and have informed, insightful info on the TH-cam. Thank you.
Another (former) pro of carbon resistors: They were the resistor to go for high frequency circuits. I love carbon resistors and still use them as ESD surge absorbers at pH meters. Instead of connecting the BNC socket to the PCB with wires we use 10K carbon compound resistors. The value and noise does not matter. No current flow and noise gets filtered out by the amplifier circuit that is made to amplify DC only. However the latest product now has SMD thick film resistors since I got mails from Digikey that the 10K OHMITE resistor will soon be made obsolete.
That was a nice explanation. It'd would have been cool to see how the value of that resistor changed after you sanded it down. I realize examples would have required a longer video and your explanation was enough to get your point across. I appreciate when you post content like this. It inspires more conversation in the comment section. Thanks. Happened to be wearing my Fazio T today.
Very cool. A fairly well known audio/electronics engineer who passed away recently left a basement filled with all manner of electronic and devices. I was able to aquire a large amount of the CC resistors that he had. I don't know who made them but, I gather that they are probably a bit old as the values have increased well beyond the color code values. I've needed to piggy back a second high value resistor in order to lower the value a bit. But, I'm happy to have them and am interested in building an amp or two with only them as the resistive elements. Why not. They are there, and I can decide for myself if I think there are any of the mytholigical stated benefits and "mojo" involved that we're heard about. Nice vid, thanks.
I own one of those same Ohmite resistor drawers. Don't ever tip it even slightly when you're carrying it or you will be sorry! Mine had apparently been filled and refilled a couple of times, and the drawers were overstuffed, and half of them wouldn't open when I took it home from the ham radio fest.
As a rule, crbons for signal, letal films for standing voltages and supplies. Laser trimmed carbon films are really good - used a lot on valve hifi as well. Fun fact: CPUs are just 'made' then tested to see what the highest speed they'll do is, then backed down and laser etched with what they are.
My late brother was an electronics tech - passed away in 1977, but I inherited an identical Ohmite resistor assortment box, full of 1/4 watt resistors.
I have a huge collection of old carbon comp resistors that I got with an old Ohmite storage bin. I went through them and checked them against what they were supposed to be, and the vast majority were ridiculously off spec. But the ones that were close I kept. I like them for no other reason than the fact that I like old stuff! And I use them when I’m doing any vintage work or any point to point work. Good video!
Nice to hear some honest commentary on carbon comp resistors. I have a MSEE from a well-known engineering institute in MA and have been practicing EE as an employee, consultant, and adjunct instructor for nearly 41 years, mostly in analog and RF design. Over these years I've learned a lot about electrical components. I often hear carbon comp resistor religious zealots rave about how carbon comps are the best and should never have other types of resistors substituted for them in vintage amps, and blah, blah, blah... These folks often uneducatedly denigrate SMT parts as "cheap," and "junk," when, in fact, they are closer to their ideal theoretical counterparts when it comes to performance due to lower parasitic values. It can get frustrating sometimes, and you video was a nice breath of fresh air. Thank you!
I could kick myself! I ran across two of these Ohmite displays in a Salvation Army store once. They wanted $75 for the set, yes there was NOS stocked inside of them. I gambled that no one would want them, so decided to wait to see if the price would come down. The next day I went in, and they were gone! Oh well. Great video as always, Colleen!
the point to point construction often turns them into little flags that vibrate with the chassis too, it can lead to surprising mechanical problems. had to drag an amp on a stool across a concrete floor to find the bad resistor once. at deafening levels it would sometimes crackle, with the scooting action it would shake like crazy. wouldn't be surprised to find out if a badly placed resistor was mechanically responsible for the tone on some early tube gear
I'm no amp tech nor am I an electronics guy at all. I just find this stuff strangely fascinating. I really like watching techs work on electronic gear. I learned something today.
Carbon Comps have a resistance coefficient to voltage so there value changes with changing voltage. Thats why they produce extra distortion and are pretty much only preferrable as plate resistors if you want that 'Mojo'. In every other application standard metal or carbon are much better suited as you have well explained.
The "varistor" effect. I have read this is actually a thing in certain applications with carbon comp. But if you are really after that sound, buy a Magnatone.
Fellow amp tech here. Agree with the 100% good info here. Well done on communicating these concepts. Keep up the great work. Outside of the plate and power supply where I also prefer non-carbon comp, in my experience, something that can be both a pro or a con is that the drifting carbon comps can significantly contribute to the "mojo" in many vintage amps. Better or worse being wholly subjective of course :) But if I find an amp that sounds particularly unique across my bench I tend to take notes of how much the carbons have moved around.
Amp techs sometimes need to compromise: if the amp is used on tours, it should also be reliable so might need to repair instead. Of course it also depends whether it is in the signal path or not.
Great explanation - and until now I have never seen the insides of a resistor, very interesting! Thank you! May I add one point ... it may even be a "pro" for the CC resistor: in my opinion the CC resistors make a somewhat smoother, rounder and more pleasent sound, when used as the first resistor in the pre-amp. Usually the signal from the guitar arrives at a resitor which is in most amps 68 kOhms, in some amps it is 22 kOhms. I have experimented in one of the amps I use and found that the CC resistor results in a smoother sound, compared to modern resistors like carbon film or metal film resistors. (Of course in my experiment the resistors showed the same value with the Ohm-Meter.) I can only assume that all resistors always show a tiny portion of capacitor-like behavior, which depends on the type of resistor. And with the CC resistor this portion is different and this leads to a different transmission of high frequencies - hence the sound is smoother while it is harsher with other types of resistors. I hope, this makes a little sense somehow...
I heard one time that there is a difference between the white and black bobbins for guitar pickups, and that black ones sound different due to carbon being used to create the color and the carbon creates a difference in magnetic conductance of the pick up. This story was in Vic Dapra's book on vintage Les Pauls.
Most informative... well explained... I've got a Vox AC-100 amplifier with cracked carbon resistors used plus a very tired looking Brimistor surge limiter on the 450volt rail. I've replaced all the caps and tubes and the 3 pots but not these croaky old resistors ... I wonder if metal film ones will be ok ( 0.25watt or 1 watt carbon film ) ...
Well done. The ability to teach sits apart from the common tech(s). Most would rather not explain; favoring to mysteriously fix issues. Your personal style of presentation not only began with the primary function of the resistor, but included an overview of when, and who created it. This is the significance that sets your channel apart from many others. Besides your channel, I subscribe to Uncle Doug, D-Lab, and Psionic (Lyle). I'm proud to count Fazio to that list. Enjoy your evening.
@@quantumbuddhistWhat does Lyle's guitar playing have anything to do with his ability to repair amps, much less resistors? Don't use Colleen's channel to troll me, or another tech. Start your own channel, so you can be pointless, and off topic all you like. Imbecile.
Got a few CC resistors though it is not my cup of tea - especially given their tendency to drift with humidity. All Keritech amps come with metal film resistors, vintage MLT (USSR, you'll probably come across them in Sovtek / EH amps) or modern production. Funny enough, I once tested how a 2W MLT resistor would handle exceeded power. I cranked it up to dissipate 7W, and while it was glowing red and the enamel burned releasing a tiny amount of magic smoke, the resistance was perfectly in spec. I sometimes found burned MLT resistors in line with screen grids; ugly but still going. I prefer wirewound 5W though.
Nice description, I am so glad you didn't mention the dumb myth that carbon resistors create some kind of sought after sound or distortion in the amp. Other than that, please replace carbon comp resistors with more modern resistor types, unless as you mention for surge protection. As an electronics engineer, I stopped using carbon comps long time ago!
The earliest telephone microphones were basically a bunch of carbon chunks situated between two electrically charged plates. This may be why carbon composition resistors crackle so much. They’re behaving like mini microphones
great video - super informative. Can you tell me, do they tend to drift in one particular direction, or no? And if they get less resistive, can this lead to other component damage, or does it just effect the sound? Love your videos, Colleen, thanks for sharing!!
Carbon comp resistors tend to drift higher in resistance when exposed to a humid atmosphere. They can be "baked out" in an oven at modestly warm temperature such as 65 degrees C to restore the original value, at least until they absorb humidity again. Having said that, I have many very-old carbon comp resistors that have been stored for decades of time in a normal non-humidity-controlled indoor environment and these remain within or close to the original specified tolerance. Good design practice was to use the carbon comps for low cost where the value and noise were not critical to the design, and to use film or wirewound resistors where tight tolerance and/or low noise was needed. In applications where carbon comp resistors dissipate enough power to get reasonably warm, or where the overall product gets reasonably warm, as in products using electron tubes, they bake out each time the product is used.
Since as we know even new old stock carbon comp resistors can become noisy while they just sit there in the parts tray, it seems a shame that we don't have some little palm size electronic device for measuring resistor noise, along the lines of the ones you can buy from Peak to check transistors and diodes, and measure capacitor ESR and so on....
How are you on metal film resistors vs. carbon film? I tend to sway to metal film but I don't work in audio nor typically with 200+ volts. I should look up the voltage specs on carbon film vs. metal film. I know resistors have a max voltage spec for each body size. I typically never have to worry about that in the low voltage stuff I usually work on/design.
Most amateur amp builders (like me) use metal film resistors except for high current applications. They are quiet. They are stable and value tolerances typically are tight compared to carbon comp or carbon film resistors.
So if you replace your old resistors with the new be aware of power surges. Thanks for showing how the resistor is constructed. Now how does resistance work in a circuit?!
Yeah, I was wondering about that too - like is there a reason to replace carbon comp resistors with carbon film or carbon comp, or just move to metal film? I would just guess that moving everything to metal film is the way to go unless there's some _really_ compelling reason not to.
IMO the main reason to use carbon composition resistors in amps is for the vintage look. Some might say they have different "mojo" but I can't speak to that.
😊Can u Explain more What is carbon Compozite! Is it carbon Sand coated on metal Resistor surfacs by using Wet Glue to Glue it Carbon Sand onto it. Is it correct !!😮
Hallo Colleen i have a problem with my solid state marshall mosfet lead. I dont get any tone then i plug in the guitar in the input, but then i plug in the send return it works find. Do you have any idea what the problem could be? All the best from Tommy in sweden
I love your videos. Nowadays you can avoid using carbon resistors. modern resistors have better reliability, less noise, better tolerance, better stability, better everything... back in the days this is the only technology we used to have. if you choose the right type, you can always avoid carbon resistor. they are good for the vintage look.
Both carbon film and carbon comp resisters make noise. Usually the film resisters are a little more quiet until you get above 100k. They are both cheaper than metal film and that's why they are used so much.
Every component in an electrical circuit is a resistor or has a level of resistance associated with it. Even the wiring. The exception is the application of superconductivity - and even here there is some resistance but but considered negligible in a practical sense. Cheers
True superconductivity has absolutely zero resistance. With no outside intervention, current will continue circulating in a superconductor and will not diminish. (It takes quantum mechanics to explain this. In the classical view, it would seem that the electrons would always eventually "bump into" something and slow down.)
@@analog_guy The strict and simple definition of superconductivity does stipulate that the electrical resistance is equal to zero and that Ohm's Law does not apply to superconductors. There are plenty of articles on residual resistance in superconductors. As Dr Rachford describes: "Zero resistance at DC below the critical current but not at higher frequencies especially as one approaches the transition temperature and/or hf approaches the gap energy. Then also there can be flux transiting the (type II) superconductor resulting in losses and an effective resistance in an applied magnetic field or just a self-induced magnetic field. Magnetic flux pinning centers are manufactured into SC tapes for magnet applications to reduce the flux transits (phase slips)." In terms of practicality we can describe superconductors as a material that has zero electrical and Ohm's Law does not apply. I have no issue with that Mr Digital_Guy
I see any carbon comp resisters have wattage values attached to them. My problem is knowing where a 2 watt resistor is required over a 1 watt, for example.
If you don't know what wattage you need you can find the voltage drop and/or in different conditions, then use Joule's law to find how much heat is generated. Double this to find a safe wattage resistor. You also need to mind the maximum voltage of each resistor type, but IIRC most carbon comps should handle at least 500 volts.
I'm not a fan of carbon comp resistors personally. They drift. They tend to be off spec with a wider "tolerance" even when "new old stock". They fail in high stress applications like at the screens, plates, and along the B+ rail. But worst of all they HISS when subjected to humid conditions and over time in certain places. But still they have this aura of superiority because that's what people used back then. I have heard that in some applications they can give a sort of slight "warble" to the sound similar to a faint vibrato which might sound subjectively....mostly around the phase inverter section....but overall I am happy to remove them and replace with wire wound.
I inherited my Dad's OHMITE container with resistors when he passed in 2014. I have it on one of my shelves in my office. He worked at Packard Bell when they made TVs and Stereos back in the 1950s and 60s. I look at the old container and remember sorting through coffee cans full of resistors salvaged from defective products. Good times.
Stick some sachets of silica gel in there, and replace them every now and then.
I’ve learned more about fixing my amps from your videos than all other fix it videos on TH-cam. I’m buying a shirt as a thank you. You make perfect videos, you explain things in detail and how I can understand
Love your explanations.I can actually understand.
A great explanation Colleen. An old ham radio trick was to trim the value of carbon comp resistors by cutting into it with a hacksaw, the deeper the cut the higher the value. Carbon comp resistors are still available from Mouser and other wholesalers, I still use them for energy absorbers across rectifier diodes (in series with a capacitor).
I LOVE your imitation of carbon comp noise! You even gracefully mimic the electrons moving thru the resistor! It’s so spot on and fun to watch! 😃
This was excellent and I hope the “101” series becomes a continuing thing. I started watching your channel and others others because I love vintage equipment for the objects they are and what they do, but I have no clue about electronics. If you could do a very basic “this is how a tube amp works” video I would love it. I’d probably be the only one of your viewers to want it, but can’t hurt to ask 😀
Thank you for an informative video Colleen, as a child, I loved the old school striped resistors and would take things apart to see all the components.
Years ago I had bought a vintage keyboard (hohner pianet), which quickly started making some nasty cracking noises (the type of noise you described). I thought it was some faulty germanium transistor, so I changed them all. It did nothing. Then I also changed a few other stuff. Again, nothing. The old guy at the electronic shop told me resistors can't really go wrong, so I didn't bother changing them. I thought it was about the pickups or transformer, or something. So I finally gave up and sold my noisy vintage keyboard, for like... almost nothing. Now I realize it was about the carbon resistors. If only someone had told me about this at the time ! 😭
Bless you for sharing your years of wisdom with us:)
So good. Absolutely spot on, accurate, and informative. It is so good to get away from the baloney and have informed, insightful info on the TH-cam. Thank you.
Wow, thank you! this is exactly the kind of info I've been trying to read about. Very informative!
Love watching your fantastic videos, Here in Northern Ireland
A million years ago ,Tony.....worked on my 62 deluxe !!!!!!! great to see Him again !!!! Cheers to You both !!!!!!!
Interesting video and also soooo relaxing!
Yours is definitely an ASMR voice!
Dang my father use to have one of those exact resistor cabinets!! He repaired TV's back then.
Colleen is the Derrek Lee of explaining stuff. Love this video so much!
Thanks For Sharing best wishes from the UK
I ❤Your Videos Coleen!! Please make them longer and more frequent like you did in the past. Regardless, All The Best!!!
Another (former) pro of carbon resistors: They were the resistor to go for high frequency circuits. I love carbon resistors and still use them as ESD surge absorbers at pH meters. Instead of connecting the BNC socket to the PCB with wires we use 10K carbon compound resistors. The value and noise does not matter. No current flow and noise gets filtered out by the amplifier circuit that is made to amplify DC only. However the latest product now has SMD thick film resistors since I got mails from Digikey that the 10K OHMITE resistor will soon be made obsolete.
I have to confess, your voice curls my toes. BTW, that's a good thing. Keep sharing!
That was a nice explanation. It'd would have been cool to see how the value of that resistor changed after you sanded it down. I realize examples would have required a longer video and your explanation was enough to get your point across. I appreciate when you post content like this. It inspires more conversation in the comment section. Thanks. Happened to be wearing my Fazio T today.
3:42: I LOVE IT how you ground the resistor. Awesome!
Very cool. A fairly well known audio/electronics engineer who passed away recently left a basement filled with all manner of electronic and devices. I was able to aquire a large amount of the CC resistors that he had. I don't know who made them but, I gather that they are probably a bit old as the values have increased well beyond the color code values. I've needed to piggy back a second high value resistor in order to lower the value a bit.
But, I'm happy to have them and am interested in building an amp or two with only them as the resistive elements. Why not.
They are there, and I can decide for myself if I think there are any of the mytholigical stated benefits and "mojo" involved that we're heard about. Nice vid, thanks.
I own one of those same Ohmite resistor drawers. Don't ever tip it even slightly when you're carrying it or you will be sorry! Mine had apparently been filled and refilled a couple of times, and the drawers were overstuffed, and half of them wouldn't open when I took it home from the ham radio fest.
What a great gift! IME the new carbon comps are pretty consistent value wise. Not metal film consistent, but not bad.
I picked up a similar drawer organizer full of NOS CC resistors a few years ago. I don't use them a lot, but it's nice to have.
I loved this. Please keep the learning videos going.
Well done and informative. So enjoy your videos !
Remember TAVA listeners comp over film is a thing in sound.. the ingredients. Love the video. ❤
As a rule, crbons for signal, letal films for standing voltages and supplies.
Laser trimmed carbon films are really good - used a lot on valve hifi as well.
Fun fact: CPUs are just 'made' then tested to see what the highest speed they'll do is, then backed down and laser etched with what they are.
My late brother was an electronics tech - passed away in 1977, but I inherited an identical Ohmite resistor assortment box, full of 1/4 watt resistors.
Super informative - thanks for posting. Learned a lot from this!
Cool! Thanks, Colleen!
Nice shout out for Tony - I met him shortly after moving to SoCal. What a character!!
I have a huge collection of old carbon comp resistors that I got with an old Ohmite storage bin. I went through them and checked them against what they were supposed to be, and the vast majority were ridiculously off spec. But the ones that were close I kept. I like them for no other reason than the fact that I like old stuff! And I use them when I’m doing any vintage work or any point to point work. Good video!
Always educating and interesting Colleen! Great score! All the best! 🌎🌍🌏❤️👍
Thanks for all the information! Keep them coming. I can't resist watching 😂
Great and informative video!
Great info. I really enjoyed that. Thank you 👍
Nice to hear some honest commentary on carbon comp resistors. I have a MSEE from a well-known engineering institute in MA and have been practicing EE as an employee, consultant, and adjunct instructor for nearly 41 years, mostly in analog and RF design. Over these years I've learned a lot about electrical components. I often hear carbon comp resistor religious zealots rave about how carbon comps are the best and should never have other types of resistors substituted for them in vintage amps, and blah, blah, blah... These folks often uneducatedly denigrate SMT parts as "cheap," and "junk," when, in fact, they are closer to their ideal theoretical counterparts when it comes to performance due to lower parasitic values. It can get frustrating sometimes, and you video was a nice breath of fresh air. Thank you!
I could kick myself! I ran across two of these Ohmite displays in a Salvation Army store once. They wanted $75 for the set, yes there was NOS stocked inside of them. I gambled that no one would want them, so decided to wait to see if the price would come down. The next day I went in, and they were gone! Oh well. Great video as always, Colleen!
See....You shuffle your feet and lose your seat! Been there myself..
the point to point construction often turns them into little flags that vibrate with the chassis too, it can lead to surprising mechanical problems. had to drag an amp on a stool across a concrete floor to find the bad resistor once. at deafening levels it would sometimes crackle, with the scooting action it would shake like crazy. wouldn't be surprised to find out if a badly placed resistor was mechanically responsible for the tone on some early tube gear
Awesome info Colleen, love this stuff!!! When can you work on my '66 Pro Reverb 😀
I thought I knew my resistors but you taught me quite a bit today! Thanks!
Great video as always!
I'm no amp tech nor am I an electronics guy at all. I just find this stuff strangely fascinating. I really like watching techs work on electronic gear. I learned something today.
Carbon Comps have a resistance coefficient to voltage so there value changes with changing voltage. Thats why they produce extra distortion and are pretty much only preferrable as plate resistors if you want that 'Mojo'. In every other application standard metal or carbon are much better suited as you have well explained.
The "varistor" effect. I have read this is actually a thing in certain applications with carbon comp. But if you are really after that sound, buy a Magnatone.
Fellow amp tech here. Agree with the 100% good info here. Well done on communicating these concepts. Keep up the great work.
Outside of the plate and power supply where I also prefer non-carbon comp, in my experience, something that can be both a pro or a con is that the drifting carbon comps can significantly contribute to the "mojo" in many vintage amps. Better or worse being wholly subjective of course :) But if I find an amp that sounds particularly unique across my bench I tend to take notes of how much the carbons have moved around.
Amp techs sometimes need to compromise: if the amp is used on tours, it should also be reliable so might need to repair instead. Of course it also depends whether it is in the signal path or not.
I learned something new, thanks!
Love your vids, pls keep making them 😊
Great explanation - and until now I have never seen the insides of a resistor, very interesting! Thank you! May I add one point ... it may even be a "pro" for the CC resistor: in my opinion the CC resistors make a somewhat smoother, rounder and more pleasent sound, when used as the first resistor in the pre-amp. Usually the signal from the guitar arrives at a resitor which is in most amps 68 kOhms, in some amps it is 22 kOhms. I have experimented in one of the amps I use and found that the CC resistor results in a smoother sound, compared to modern resistors like carbon film or metal film resistors. (Of course in my experiment the resistors showed the same value with the Ohm-Meter.) I can only assume that all resistors always show a tiny portion of capacitor-like behavior, which depends on the type of resistor. And with the CC resistor this portion is different and this leads to a different transmission of high frequencies - hence the sound is smoother while it is harsher with other types of resistors. I hope, this makes a little sense somehow...
I heard one time that there is a difference between the white and black bobbins for guitar pickups, and that black ones sound different due to carbon being used to create the color and the carbon creates a difference in magnetic conductance of the pick up. This story was in Vic Dapra's book on vintage Les Pauls.
Great video - learned a lot! Also learned that Loud Amps Save Lives. Who knew? :)
Love your body of work. Very informative. Thank you!
Well said. Clear and concise. I know better now that there is something cool about the 'bumblebee' resistors.
Thank you for sharing knowledge
Most informative... well explained... I've got a Vox AC-100 amplifier with cracked carbon resistors used plus a very tired looking Brimistor surge limiter on the 450volt rail. I've replaced all the caps and tubes and the 3 pots but not these croaky old resistors ... I wonder if metal film ones will be ok ( 0.25watt or 1 watt carbon film ) ...
Well done. The ability to teach sits apart from the common tech(s). Most would rather not explain; favoring to mysteriously fix issues. Your personal style of presentation not only began with the primary function of the resistor, but included an overview of when, and who created it. This is the significance that sets your channel apart from many others. Besides your channel, I subscribe to Uncle Doug, D-Lab, and Psionic (Lyle). I'm proud to count Fazio to that list. Enjoy your evening.
@@quantumbuddhistWhat does Lyle's guitar playing have anything to do with his ability to repair amps, much less resistors? Don't use Colleen's channel to troll me, or another tech. Start your own channel, so you can be pointless, and off topic all you like. Imbecile.
Nice! I learnt a lot thanks 😊
Got a few CC resistors though it is not my cup of tea - especially given their tendency to drift with humidity. All Keritech amps come with metal film resistors, vintage MLT (USSR, you'll probably come across them in Sovtek / EH amps) or modern production.
Funny enough, I once tested how a 2W MLT resistor would handle exceeded power. I cranked it up to dissipate 7W, and while it was glowing red and the enamel burned releasing a tiny amount of magic smoke, the resistance was perfectly in spec. I sometimes found burned MLT resistors in line with screen grids; ugly but still going. I prefer wirewound 5W though.
We didn't miss those resistors when better ones came long that were quieter and more predictable tolerance wise.
But it's fun to see them.
Great videos!
Great video.
Excellent very informative
Very good! 👍
Good stuff!
Nice description, I am so glad you didn't mention the dumb myth that carbon resistors create some kind of sought after sound or distortion in the amp. Other than that, please replace carbon comp resistors with more modern resistor types, unless as you mention for surge protection. As an electronics engineer, I stopped using carbon comps long time ago!
I have two of those little containers of resistors! I wonder if I could get big bucks from a science museum? 😂 I got them back in the ‘70’s.
Great stuff! But I was hoping that just recapping my 1482 and new tubes would get rid of the noise! Thanks....
I have 5 resistor cabinets mine are all metal silver and blue in color I use all types of resistors in my repairs and designs !
The earliest telephone microphones were basically a bunch of carbon chunks situated between two electrically charged plates. This may be why carbon composition resistors crackle so much. They’re behaving like mini microphones
great video - super informative. Can you tell me, do they tend to drift in one particular direction, or no? And if they get less resistive, can this lead to other component damage, or does it just effect the sound? Love your videos, Colleen, thanks for sharing!!
Carbon comp resistors tend to drift higher in resistance when exposed to a humid atmosphere. They can be "baked out" in an oven at modestly warm temperature such as 65 degrees C to restore the original value, at least until they absorb humidity again. Having said that, I have many very-old carbon comp resistors that have been stored for decades of time in a normal non-humidity-controlled indoor environment and these remain within or close to the original specified tolerance. Good design practice was to use the carbon comps for low cost where the value and noise were not critical to the design, and to use film or wirewound resistors where tight tolerance and/or low noise was needed. In applications where carbon comp resistors dissipate enough power to get reasonably warm, or where the overall product gets reasonably warm, as in products using electron tubes, they bake out each time the product is used.
@@analog_guy super information - thank you so much!!
As @analog_guy said, they usually drift up. However, they can also drift down if they have been overloaded.
Do you repair Orange Amps? If so, what are your thoughts on them?
I thought you should have also mentioned and talked about metal film resistors too.
Since as we know even new old stock carbon comp resistors can become noisy while they just sit there in the parts tray, it seems a shame that we don't have some little palm size electronic device for measuring resistor noise, along the lines of the ones you can buy from Peak to check transistors and diodes, and measure capacitor ESR and so on....
How are you on metal film resistors vs. carbon film? I tend to sway to metal film but I don't work in audio nor typically with 200+ volts. I should look up the voltage specs on carbon film vs. metal film. I know resistors have a max voltage spec for each body size. I typically never have to worry about that in the low voltage stuff I usually work on/design.
Most amateur amp builders (like me) use metal film resistors except for high current applications. They are quiet. They are stable and value tolerances typically are tight compared to carbon comp or carbon film resistors.
So if you replace your old resistors with the new be aware of power surges.
Thanks for showing how the resistor is constructed.
Now how does resistance work in a circuit?!
Wonderful opinions
Give us more
It would be really useful if you mentioned a reason and justification for using carbon comps in amps these days.
Yeah, I was wondering about that too - like is there a reason to replace carbon comp resistors with carbon film or carbon comp, or just move to metal film? I would just guess that moving everything to metal film is the way to go unless there's some _really_ compelling reason not to.
IMO the main reason to use carbon composition resistors in amps is for the vintage look. Some might say they have different "mojo" but I can't speak to that.
😊Can u Explain more What is carbon Compozite! Is it carbon Sand coated on metal Resistor surfacs by using Wet Glue to Glue it Carbon Sand onto it. Is it correct !!😮
Hallo Colleen i have a problem with my solid state marshall mosfet lead. I dont get any tone then i plug in the guitar in the input, but then i plug in the send return it works find. Do you have any idea what the problem could be?
All the best from Tommy in sweden
this rocks
Given the cons, do you still replace the resistors with good carbon comp resistors or do you use more modern types of resistors as replacements?
She mentioned that she replaces them with carbon film resisters. Another branch on the resistor tree!
Life is like a box of carbon comp resistors, Forrest. You never know what you're gonna get.
5:15 Colleen clears throat!
Grazie infinite 👍🏻💯
I love your videos. Nowadays you can avoid using carbon resistors. modern resistors have better reliability, less noise, better tolerance, better stability, better everything... back in the days this is the only technology we used to have. if you choose the right type, you can always avoid carbon resistor. they are good for the vintage look.
When carbon comp resistors start to drift in value is it in one particular direction? Up in value or down?
Usually carbon composition resistors drift up in value.
When I need low-induction resistors, I use carbon film resistors, but they tend to produce more noise, especially as they age.
I thought the carbon comp made noise ..isn't that what she said?
Both carbon film and carbon comp resisters make noise. Usually the film resisters are a little more quiet until you get above 100k. They are both cheaper than metal film and that's why they are used so much.
are carbon film resistors less noisy? how do they compare to metal film?
Yes they are! I like carbon film for signal path resistors, and metal film for power supply
Every component in an electrical circuit is a resistor or has a level of resistance associated with it. Even the wiring. The exception is the application of superconductivity - and even here there is some resistance but but considered negligible in a practical sense.
Cheers
True superconductivity has absolutely zero resistance. With no outside intervention, current will continue circulating in a superconductor and will not diminish. (It takes quantum mechanics to explain this. In the classical view, it would seem that the electrons would always eventually "bump into" something and slow down.)
@@analog_guy The strict and simple definition of superconductivity does stipulate that the electrical resistance is equal to zero and that Ohm's Law does not apply to superconductors.
There are plenty of articles on residual resistance in superconductors.
As Dr Rachford describes:
"Zero resistance at DC below the critical current but not at higher frequencies especially as one approaches the transition temperature and/or hf approaches the gap energy. Then also there can be flux transiting the (type II) superconductor resulting in losses and an effective resistance in an applied magnetic field or just a self-induced magnetic field. Magnetic flux pinning centers are manufactured into SC tapes for magnet applications to reduce the flux transits (phase slips)."
In terms of practicality we can describe superconductors as a material that has zero electrical and Ohm's Law does not apply.
I have no issue with that Mr Digital_Guy
Join the resistance. 🤓
I see any carbon comp resisters have wattage values attached to them. My problem is knowing where a 2 watt resistor is required over a 1 watt, for example.
If you don't know what wattage you need you can find the voltage drop and/or in different conditions, then use Joule's law to find how much heat is generated. Double this to find a safe wattage resistor. You also need to mind the maximum voltage of each resistor type, but IIRC most carbon comps should handle at least 500 volts.
I couldn't miss your channel today.... Resistance is futile.
so what are you faceting on the stone
Super Showman head! Where are the cabs?
I'm not a fan of carbon comp resistors personally. They drift. They tend to be off spec with a wider "tolerance" even when "new old stock". They fail in high stress applications like at the screens, plates, and along the B+ rail. But worst of all they HISS when subjected to humid conditions and over time in certain places. But still they have this aura of superiority because that's what people used back then. I have heard that in some applications they can give a sort of slight "warble" to the sound similar to a faint vibrato which might sound subjectively....mostly around the phase inverter section....but overall I am happy to remove them and replace with wire wound.
What about diode effect?
let's talk about that 60ish GA-5