I realize that technical videos are not as entertaining or popular as regular videos, but I felt compelled to post an easily searchable how-to video on a frequently-requested topic. As mentioned, the '69 Twin Reverb Extravaganza will be posted soon.....so turn your beer coolers down to 31.9 degrees F and get ready !!!
@billgreen4592
4 жыл бұрын
For those of us the fix/build amps, these videos are what really makes you channel valuable! Thanks for this content.
@paulvale2985
4 жыл бұрын
Informative AND entertaining Unc, Keep up the good work 🔊
@knifeswitch5973
4 жыл бұрын
You do what ever the hell videos you want to do Doug. It’s all brain candy and it’s all good
@jogreeen
4 жыл бұрын
I love watching Jack riff on refurbished amps, but these tech vids are some of your best, there aren't many people doing this stuff on KZitem.
@Wildman9
4 жыл бұрын
A AN 764 model Twin Reverb,whoops. These type videos are just fine for those of us who like to do biasing , on our own and doing it right. By the book.📖 🎸👍
@erra9490
4 жыл бұрын
This is gold! Thank you. If I had this useful application of math in high school, I might have retained it back then. Thank you Uncle Doug ( and all your supporters) for sharing these videos and tutorials.
@UncleDoug
4 жыл бұрын
You're quite welcome, ER. Glad you enjoyed the video.
@kenporonin1
4 ай бұрын
Great explanation..... thanks for sharing your knowledge to a new tube guy.....!
@UncleDoug
4 ай бұрын
Thanks, Ken. Glad you enjoyed it :)
@kenporonin1
4 ай бұрын
@@UncleDoug Thank you uncle Doug. I recently purchased a Dual Mono Block Marshall EL-34 100/100 which I plan to use as an audio amp/receiver (not as it's intended use as a guitar amp). I don't think the tubes need repacing as everything sounds pretty good as is. However, I was interested was interested in tube biasing when the need comes.
@UncleDoug
4 ай бұрын
@@kenporonin1 It's best to check the biasing before use, Ken. I have found it hazardous to trust previous owners.....or even builders.....to adhere to proper biasing levels.
@kenporonin1
4 ай бұрын
@@UncleDoug Thank you..... I will check them myself.
@UncleDoug
4 ай бұрын
@@kenporonin1 You may be surprised by what you find. Good luck :)
@moorec1053
3 ай бұрын
In a quad, with parallel plates, could you pull one tube and measure that current, then remove that tube and put the other one in and measure the current of that tube. Would that give you an accurate measure of the current for each tube in the pair.? Thank You
@UncleDoug
3 ай бұрын
No, because the absence of any tube will alter the PC through the otherr tube.
@shekador
4 жыл бұрын
As Alanis Morissette once sang, "I've got one hand in my pocket, and the other one is measuring plate voltage"
@UncleDoug
4 жыл бұрын
Alanis was one of our best students, Shek ;)
@Rightnow0101
4 жыл бұрын
I thought that but didn't want to post it. :)
@Rightnow0101
4 жыл бұрын
@@DL-oy2qn Yeah, I really do think....and I've seen the effect of grounding a metal watch band to a chassis in person. It leaves a mark for sure.
@PandemoniumMeltDown
4 жыл бұрын
@@DL-oy2qn Don't you think? A little toooo ironic... yeah!
@billguitarvin
3 жыл бұрын
shekador - LOL!!!!! I got a good laugh from your comment. Thanks for the funny comment. Always wondered what the lyrics were in that part of the song. 🙂
@anthonyderosa5181
4 жыл бұрын
Love your videos Uncle Doug! With all due respect I would like to point out one thing. In your example of the quad output tubes (14:28) you discuss plate voltages on the two plates which are connected in parallel. The voltage measurements will be the same, they will not differ on the two tubes. What will be different, unless the two tubes are perfectly matched is the plate current of each tube. The rules for a parallel circuit are as follows: The voltage on each branch of a parallel circuit is the same, the branch currents add up to equal the total current. Thank you for making these great videos.
@UncleDoug
4 жыл бұрын
Good point, Anthony. Thanks for your helpful input. I have added a statement to the video description clarifying this issue. Regardless of the relative current flow through the paired, parallel tubes, the voltage measured at the plate (anode) will be the same.
@rossthompson1635
4 жыл бұрын
I thought that but then I wondered - yes that would be true for grid biased tubes (ground to the common point between the plates), but wouldn't the voltage still differ for cathode biased tubes - i.e. you are measuring voltage across the tube which will be proportional to the current through each?
@Dr_Reason
4 жыл бұрын
@@rossthompson1635 I think they cannot vary in voltage since they are connected to the same voltage source. Their amp flow can vary if the tubes vary.
@bobvecchi7981
4 жыл бұрын
@@rossthompson1635 no, the voltage will be the same, but the current will be proportional as a result of the tube’s internal resistance being different, hence the term mismatch”.
@ichbinnutzlos5561
Жыл бұрын
Change one opposite pair of tubes to check wether plate current changes without changing bias.
@scottbc31h22
4 жыл бұрын
VIDEO REQUEST Please do a video about the relationship of the tube output impedance and transformer impedance when using a quad of tubes, As a follow up to this video and your series regarding output transformers. Thank you! PS I love your videos! These are the best, easiest to understand, tutorials I have ever seen.
@UncleDoug
4 жыл бұрын
As you probably know, Scott, identical resistors in parallel have a total resistance equal to half of either of the individual resistances.....i.e. two 100 Ohm resistors in parallel have an effective combined resistance of 50 Ohms. The same is true with quad tube sets. The Load Resistance is one-half that of a double-ended pair.
@scottbc31h22
4 жыл бұрын
@@UncleDoug Thank You.
@MrGTO-ze7vb
4 жыл бұрын
Uncle Dougski is one Fantastic Teacher..!!! some teenager in 2056 will need to watch this video after inheriting a Fender Amp and purchasing new output tubes.
@UncleDoug
4 жыл бұрын
Thanks so much. I sure hope so, Mr. G. :)
@raulhernandez4300
3 жыл бұрын
With all due respect, I don't see how the plate voltage will differ if fed by the same soure. If the tubes are not matched, only the plate currents will differ. On the two tubes in parallel. I would like to see you put your meter p-p and see what reading you get!
@UncleDoug
3 жыл бұрын
You're right, Raul. This error was discovered long ago and corrected in the video description. Thanks for your input.
@DAVIDGREGORYKERR
4 жыл бұрын
I wonder if that guitar amplifier that you showed could be redesigned to use the RAYTHEON miniature vacuum tubes to make for a smaller more transportable amplifier about the size of a woman's handbag and hopefully make the unit work of 24-90V B+ supply and 3V Heater supply what about it.
@circuitsandcigars1278
4 жыл бұрын
Problem is the Raytheon tubes are no longer made
@DAVIDGREGORYKERR
4 жыл бұрын
@@circuitsandcigars1278 That is a bummer as they would permit the manufacture of small vacuum based guitar amplifiers as they would have more gain and higher power handling than the KORG 6P9.
@alanbrower9969
3 жыл бұрын
Hi Doug, I love your videos! I have a question that's a little off topic for this video: I saw on the data sheet in your video the max plate dissipation of 12w for the 6v6. I also saw the max plate voltage at 315v. I see dual ended 6v6 amps typically above 400v plate voltage (kudos to you for using a real world voltage in your example calculations). I know that's what sounds good and I've used that voltage in some of "my" designs. How is it that we all get away with applying a voltage that is that far above the listed max plate voltage? Your videos rock, the only request I could make is to ask for more Rusty and Jack!
@UncleDoug
3 жыл бұрын
Thanks, Alan. Apparently the 315VDC max rating is absurdly conservative. Fender routinely drove their 6V6's in Champs, Princetons, Deluxe Reverbs, etc. to 425V and above, with no apparent harm. As long as the plate current is sufficiently low to provide a sub-12W (cathode-biased) or 8.4W (grid biased) plate dissipation, all is well.
@emergencynurse02
4 жыл бұрын
Great Video...! Thank you ..... Indecently Defibrillators DO NOT Restart a heart....They will not deliver a shock unless they sense a rhythm....Defibrillators are intended only to correct a life threatening rhythm....Like Vtach or Atrial Fibrillation that causes loss of consciousness and impending death. If the heart is in asystole (no detectable rhythm) then you need to continue CPR until the problem is found and corrected.
@UncleDoug
4 жыл бұрын
So those little paddles they apply to start a stopped heart after surgery or a transplant are just TV make believe, GH ?? Those lying phonies !!
@MrRadioGypsy
4 жыл бұрын
Hey Uncle Doug: Do you find much DC leakage in the coupling caps to PA stage? My observations watching other amp repairmen reveals they just go ahead and replace them. But how much DC % or voltage is considered too much before they should be replaced? Thanx!
@UncleDoug
4 жыл бұрын
By observing the stability of the Plate Current during operation you can ascertain the status of the coupling caps.....and there was no leakage noted. Why replace fully functioning vintage parts with possibly questionable Chinese caps, unless it is necessary ?
@ElmoSyr
7 ай бұрын
Thanks again Doug! I remember watching these videos a few years ago and having no idea how to even start touching tube amps. I've since then become a part of a small repair tech team and am making an alright side business with it. A big start and encouragement for me were your videos. So I'd like to thank you once again for making such great videos!
@UncleDoug
7 ай бұрын
That's great too hear, Elmo. We're glad the videos were informative and helpful :)
@bertrodriguez3087
4 жыл бұрын
Technical videos are the reason I fell in love with your channel. I don't know if I love you or hate you (LOL), but having worked on just about everything in my lifetime (I'm sure, just like you), your "How Tubes Work Videos" set me on a path. Again, I don't know if that was a good thing, because I've had to fix a ton of amps for my musician friends (and I have many) over that last few years. And I have fixed a bunch of circuit board amps (which I know you don't like to do), Peavey 6534+, 5150, Marshall 800, 900, 2000, etc. My background is in computers so I was used to circuit boards. This was all thanks to your very clear and precise explanations on the "WHY and HOW" it works like that (for tubes and amps). To me, at least, that's top of the list. You must have been a hell of a teacher. We need more teachers like you in this day and age, and I don't mean to embarrass you, that's just a fact. God bless you and thanks for all you do.
@UncleDoug
4 жыл бұрын
Wow, thanks so much for your very nice comments, Bert. Hearing from viewers like you makes it all worthwhile :) Likewise on the blessings.
@MrGTO-ze7vb
4 жыл бұрын
I just purchased a 1990? Fender Twin Amp. It was just missing 2 output tubes, all the pots needed Deoxit cleaning and the 2 speakers were out of phase. I purchased a matched quad set of tubes and installed them. Luckily on the back panel there is a bias adjustment pot, test points and output balance adjustment
@UncleDoug
4 жыл бұрын
I hope it turned out to be a great amp, Mr. G.
@MrGTO-ze7vb
4 жыл бұрын
@@UncleDoug So far ... Very good.!! Someone replaced lots of the caps!! It does put out some great tones..! Thank you Uncle Doug..!!
@brucebuckeye
3 жыл бұрын
Thank you Uncle Doug!! I have learned so much from you this year, since I started watching. I was an electrical engineer for 34 years in the Air Force (civilian), and I retired on 31 December 2019. I have always strived to be able to explain things easily like you do and keep the calculus out! I like to understand what is really happening and why - that is the way to solve problems! You are a master at teaching! Stay healthy!
@UncleDoug
3 жыл бұрын
Thanks so much, Bruce. Will do......you too, I hope :)
@davidbuzzin426
4 жыл бұрын
👍🇺🇸❤
@michaeldowning796
4 жыл бұрын
Thanks UD!
@djfrank59
4 жыл бұрын
Hi Doug! once again, another valuable and informative video. Entertainment is one thing, but the young and upcoming techs NEED to watch the most important videos such as this one. I like entertaining videos, but I also like the meat and potatoes when it comes to the theory. Your explanation is spot on. Without the theory, the how and why remains unknown, and its like shooting in the dark without a flashlight which isn't good; the bullets can fly anywhere. There are so many different ways to measure and set bias, but a VTVM and pencil and paper tells the accurate truth which I feel is important. I think a balance of both, entertainment and theory would be the best direction to go in. You will have it all covered on both ends that way. I enjoy the non-entertaining as well; that's why your past videos were a great teaching aid when I taught at the vocational school. Keep this great flow and balance going. you're onto something good :)
@UncleDoug
4 жыл бұрын
Wow, thanks so much for your very nice comments, Frank. Coming from you, they mean a lot.
@rickbaker4571
4 жыл бұрын
Be still my heart!! oh, she's pretty!
@m1km1sh1n
4 жыл бұрын
👍😊
@GeorgeChristofi
4 жыл бұрын
A great explanation video of how to measure plate current Doug. Looking forward to the video showing how you actually set the bias on both cathode bias and grid bias. I'm guessing with the cathode bias you add to the plate resistance and with grid bias you change the grid voltage.
@UncleDoug
4 жыл бұрын
Thanks, George. In cathode bias the cathode bias resistor value is adjusted to alter the negative charge on the grid, relative to the cathode.
@KorAllRBare
4 жыл бұрын
🐨 keep hand in PANTS!!! Gotcha!.. Later that day...😏 Dee "The Missus" screams " SPRUNG!!! " 😳 To which Hand is ejected quickly out of pants 💨 To which ended in an electrifying climax for the both of us. 😊
@UncleDoug
4 жыл бұрын
No distractions, like "pocket pool", KB.....after all, we're grown-ups......aren't we ???????
@KorAllRBare
4 жыл бұрын
@@UncleDoug 🐨 Naw.. But, But, BUT 😟 it's good to have a little fun now n again.. 😧 😃
@gavinmonson6574
3 ай бұрын
Great explanation! Do you think it would improve the tone of the amp to modify it to enable biasing each output tube individually? Or are ‘matched’ tube quartets sufficient? Thanks!
@UncleDoug
3 ай бұрын
Thanks, Gavin. Many peeople feel that output tubes which are slightly to moderatly mismatched produce better tone. Test it and see if you agree.
@willclarke4631
2 ай бұрын
I’m going through all these technical videos again preparing for my second amp build. Got to say doing a hands on project really helps me understand the nuances of these excellent videos. I’m having so much fun doing these projects and I don’t know if I could do it without Uncle Doug.
@UncleDoug
2 ай бұрын
That's great to hear, Will, and the perfect way to master a new skill.....develop a solid foundation through study, then put what you know into practical use.
@terencekaye9948
4 жыл бұрын
Hi Doug,, Super Great Tech Video,,,, Thank you for posting it,,,
@UncleDoug
4 жыл бұрын
You're very welcome, Terence. Thanks !!!
@thanapoll.849
2 жыл бұрын
Suppose use RE084 DHT tube (bias by filament bias using filament resistor of 27R) Volt Anode 150VDC 6mA and feed 6.1VDC 80mA to filament pin the voltage of another filament pin will be (6.1V-3.8V tube need 3.8V)= 2.3VDC Why 2.3VDC total current of 80mA + 6mA = 86mA across 27R (filament resistor) need to have large 20-watt resistor. Under ohms law the watt is only 0.1978 watts. Why 1 watt resistor is not enough and need such a very big 20-watt filament resistor? In contrary when using fixed bias (sensing resistor to measure mA is only 0.25 watt value 1R very small resistor). Thank you
@UncleDoug
2 жыл бұрын
All of this is way too confusing for my poor old brain, TL. Sorry, I can't offer the help you seek..
@MrTimcoronel
4 жыл бұрын
thanks Uncle Doug. Instructive as ever. 1970s Twins were rated at 135 watts -- does that mean each 6L6 was putting out ~35w? What sort of voltages would that entail?
@UncleDoug
4 жыл бұрын
That's a good question, Tim, since the tube handbook states that the max output of a 6L6GC at 450V on the plate is 50W. I suspect it's like the horsepower figures quoted for 1960's cars.
@davidklang8174
4 жыл бұрын
The Fender 135 models put 500VDC on the plates and screens at idle (screens connected to a tap at only about 12% of the winding so it doesn't swing as much as with a true ultralinear tap). I'm sure a quad of 6L6GCs could give you about 135W that way. A pair of 7027As, which is the same tube, with different pinout (really, it is) will do 76W at 540V plate and only 400V screen. A little voltage goes a long way, outputwise.
@DonnTarris
Жыл бұрын
Hi Doug, I've just picked up Epiphone's answer to a twin style, quad output guitar amp. I'm reviewing two of the videos you've done on the Fender Twin models (1968 and 1978) and this video on biasing quad output tubes, couldn't be more valuable. The Epiphone Embassy is very similar to the Gibson GA-95RVT, other than one of the 9 pin tube locations using a 12AU7 (Epi) instead of a 12AX7 (Gibson). The Epiphone I've picked up is from 1966. The amp had been "serviced", but the tech hadn't realized that someone before him had added a 6th 9 pin tube (12AX7) to the chassis in a factory opening - probably used in another model that used the same chassis. Now I'm in the midst of going over the schematics for the Embassy amp, the GA95RVT (which the tech who had checked the amp out figured was closer to the amp) and a fabulous find - a meticulously created drawing of the eyelet board for a GA95RVT that I found on a blog. Like the 1978 Fender Twin you went over, this amp has to be checked end to end to figure out where I'm starting at - a very good part of this educational journey. Getting there, thanks to what I've learned from watching a multitude of the videos you've created! While the more technical videos may not get as many folks viewing, they are greatly appreciated by folks like me!! Cheers from the wet coast of Canada!!
@UncleDoug
Жыл бұрын
Wow.....Thanks for sharing this with us, Donn. It sounds like quite an excellent acquisition. Best wishes for continued success with your circuit overhaul.....and for a wonderful holiday season.
@PandemoniumMeltDown
4 жыл бұрын
"Vertical Deflection Amplifier - Triode Connected / Peak Positive Plate Voltage (Abs. Max.) 1200V" (!!!) Is this a usual condition or a kind of Hi-Pot value, rare occurence... ? Very few people have a multimeter rated 1200V...
@UncleDoug
4 жыл бұрын
I have never seen a DMM rated for more than around 600V, PM.
@tayro7265
4 жыл бұрын
I found this www.audioamp.eu/en-detail-901899156-modules-for-to-optimize-bias-with-an-supply-of-bias-ab-q.html the other day. Has anyone used this module? Any opinions?
@UncleDoug
4 жыл бұрын
I have not. Hopefully some viewer(s) will respond, TT.
@ruth-michaelschmitz9552
Жыл бұрын
Uncle Doug, do you have any videos on how driver circuits requirements must change when going from the 2 tube output to the quad output? I have a great schematic for a GU50 PP amplifier which uses two output tubes on a 2400 CT 2400 output transformer rated at 100W. I have quite a few Douglas transformers originally made for a different tube and a configuration with 1200 CT 1200 at 200W. I want to double up the GU50s to drop the impedance so I can use those transformers I have. The original schematic shows as a driver tube 6414W with both triodes paralleled to drive the GU50. Is the same circuit capable to drive 2x GU50 because tubes are voltage devices, or do I have to do extensive calculations to modify the driver stage to make it work properly, because paralleling of two output tubes will drop the input impedance and that might spell trouble for the 6414W to be overloaded. Kindly give me your take on this to learn or point to an eventual video you may have on this issue. Thanks!
@UncleDoug
Жыл бұрын
My experience with quad output amps is limited to the Fender Showman AA-763, which uses a conventional long-tailed pair phase inverter to drive the four output tubes. I see no special provisions to increase the driving power over that seen in the standard dual-output-tube circuits.
@rogerhowell9474
4 жыл бұрын
Great and informative video as always Mr. Doug. Thank you, Roger in San Angelo.
@UncleDoug
4 жыл бұрын
Our pleasure, Roger. Always good to hear from a fellow Texan.
@jimirox1928
4 жыл бұрын
Sorry to disagree Uncle Doug but - DCV fixed biased tubes pushed hard (club/rehearsal volume Rock & Roll) will sound like static is coming through the speakers. It's just cold for a Marshall EL34/6550 or Fender 6L6/6V6 amp. I've tried all different PD %'s and for a fixed bias amp ~75%-82% seems to be the sweet spot for sweet creamy dirt. ; )
@UncleDoug
4 жыл бұрын
Thanks for your input, Jimi. It's good to hear different viewpoints.
@jasongcicero3488
4 жыл бұрын
That was the best explanation/presentation of the process of biasing that I have ever seen. You are a really good teacher!!!!
@UncleDoug
4 жыл бұрын
Wow, thank you, Jason.
@ag6478
3 жыл бұрын
Have you written a book, Uncle Doug? I'd buy it. I'd contribute to a fund to support writing it, as well. Thanks for the knowledge, sir!
@UncleDoug
3 жыл бұрын
We think of our videos as a readily available, electronic "book", AG.......and (unless you choose to become a Patreon patron) it's free :)
@HELLHAMMERHANDHIX
4 жыл бұрын
Dear Mr doug ... are you suggesting that we touch ourselves whilst working with electronics ???. And if so ,are we allowed to touch other people ???.
@UncleDoug
4 жыл бұрын
No "pocket pool" during working hours, Nic.....it may distract you from the job.
@cbennz514
4 жыл бұрын
Another wonderful video, thank you!! By far you have the most informative youtube tube amp channel. Any chance you could explain an ultralinear amp to power low efficiency speakers? Thanks again!
@UncleDoug
4 жыл бұрын
Thanks so much, CB. I will keep your suggestion in mind.
@JDPri77
4 жыл бұрын
First of all, who wouldn't find this interesting? In fact, just last night part of that question came up. I was looking over the specs of my recently purchased Deluxe Reverb, saw the output tube specs of(2) 6v6s. The amp is 22 watts and fits everything I need in home or occasional performance use, especially these days where we mic all the instruments for a performance. But then, I remember in my band during high school years back in the 70s, the guitar players had Twin Reverbs. A 65 Twin reissue has 85 watts and in the70s I think it was closer to 100 watts. Why did we have those high wattage amps? We didn't have the$$$ for 20+ channel boards and we had to be louder than the drummer. So we sacrificed sound quality for sound quantity. Anyway, I was looking up the tube complement for a 65 Twin Reissue and it is (4) 6L6. Hmm UD has never talked about 4 output tubes... But wait, now he has provided instructions on how to bias the tubes. The only thing left is how does the push pull work with four output tubes? Well I guess that's for another video.
@UncleDoug
4 жыл бұрын
Thanks for your comments, JD. The pairs operate exactly like single tubes do in DE amps. One pair "pushes" while the other pair "pulls".....but since each pair is twice as powerful as a single tube, the output from the amp is much greater.
@GL64
4 жыл бұрын
Clear and concise and informative as always. Thanks! I've been steadily adding 1% 1 ohm resistors to the cathodes of my grid bias amps to get quick and easy bias readings at each tube. It's a little work initially, but the end result is easier than fumbling around with hot tubes and bias probes. The manual math method is about as true as it gets though.
@UncleDoug
4 жыл бұрын
Thanks, GL. That's one way to determine the PC matching within each pair of tubes......instead of just getting the average.
@EverythingsConnected.
4 жыл бұрын
Hello Uncle Doug. Love your videos and truly appreciate the work you share. I have a question/concern that I hope you can shed more light on. I have a 1985 Fender Concert 4 x 10 amp. I don't know a thing about electronics. Should I be concerned for my life about using an amplifier this old? In other words, Are there any components that wear out over time that could possibly introduce a hazard? If so, what could I check/fix to Mitigate this possibility? Thank you in advance.
@UncleDoug
4 жыл бұрын
Thanks, Kris. If it still has a 2-wire power cord and a Ground toggle switch, you would be much better off having a chassis-grounding 3-wire power cord installed. Doing so would resolve any shock hazards.....as long as your AC outlets are properly wired.
@rolandmengedoth2191
2 жыл бұрын
Execellent explaination of the subject without very deep maths. Just ohms law, thats it !
@UncleDoug
2 жыл бұрын
Glad you enjoyed it, Roland :)
@Silent-Lucidity
11 ай бұрын
Another excellent tutorial! Thank you UD for all this great content!
@UncleDoug
11 ай бұрын
You're welcome, S-L :)
@lifegettingintheway2710
8 ай бұрын
There is an error at 14:39 when describing the plate voltages of tubes with dissimilar plate current. Because the tubes are hardwired in parallel they will always have identical plate voltages regardless of the plate current each carries. It is identical to two resistors in parallel but having dissimilar resistances - the voltage measured across them will not change but the current they carry will be different. With tubes this simply means the tubes have dissimilar internal resistance. In cathode biased circuits the cathode to ground voltage will be very different between parallel tubes. The cause of unbalanced plate current could indicate a manufacturing error or external component/soldering problems (screen or cathode resistors, for example). Thank you for all you do to educate all of us. These technical discussions are fascinating to this old tube amp engineer.
@UncleDoug
8 ай бұрын
Thanks for your knowledgeable input, LG.
@jayahn9399
Жыл бұрын
I have been enjoying your video so much as of late. Thank you so much, please keep it up, and keep us informed on the subject matters.
@UncleDoug
Жыл бұрын
Thanks, J. Will do :)
@dennislarson9560
4 жыл бұрын
So the output tube bias doesn't change if there are two tubes in push pull or there are four tubes in push pull. Does that work if you remove one each of the push and one of the pull? Would that be an effective way to lower output, either by a switch or physical removal. Can i assume that this will work regardless of the output tube; 6L6, 6V6, EL84, EL 34?
@UncleDoug
4 жыл бұрын
Yes, you can remove one tube from each pair to reduce output, but I would recheck the bias of the remaining tubes.
@DrHumbertoable
4 жыл бұрын
Thirsty for theory , thanks alot for a great video. All thumbs Up!
@UncleDoug
4 жыл бұрын
Glad you enjoyed it, Dr. H.
@robertjones6324
4 жыл бұрын
Excellent lesson! Glad you gave us the safety precautions too.
@UncleDoug
4 жыл бұрын
Glad you liked it, Robert. Be safe :)
@-dazz-
4 жыл бұрын
There's one thing I don't quite understand. In that Twin Reverb, and most quad amps (as far as I know) tubes are paralleled in pairs. So each pair has their plates connected with a dead short. Wouldn't that be forcing the same plate voltage in each paralleled pair, irrespective of their individual plate current? Sorry if that's a stupid question, I'm probably missing something
@UncleDoug
4 жыл бұрын
It's not stupid at all, Dazz. You are absolutely correct. I have added a note in the video description clarifying the mistake.
@jedishaw6771
Жыл бұрын
I personally really like your technical videos! Thank you.
@UncleDoug
Жыл бұрын
I'm glad to hear that, Jedi :)
@dougtaylor7724
4 жыл бұрын
I loved your video! Always great content and well explained. However, the cats seem to hide and I feel they are the ones making you feel like the viewing public seems less interested. I’m afraid they could be giving you bad intelligence.
@UncleDoug
4 жыл бұрын
Those cats can be pretty treacherous, especially when there are treats up for grabs. I'll keep a closer eye on them. Thanks.
@felix-antoinedandenault4799
4 жыл бұрын
Do you have experience in comparing vintage amp form the transition period between cotton and plastic insulated hook-up wire, tone wise, tightness?
@UncleDoug
4 жыл бұрын
Short leads reduce noise, but I don't believe the type of insulation or wire has any effect on tone.
@mrGoesto11
3 жыл бұрын
Does every amp have a center tap type OT? It seems that they are essential in making these calculations. How are they typically identified in the amp layout? I was looking at a friends Orange amp (some of their schematics are not published) and couldn't identify where the center tap was or even if there was one since I don't know what they typically look like.
@UncleDoug
3 жыл бұрын
Only OPT primaries intended for double-ended use have center taps, Mr. G. To find it, look at the wires coming from the OPT primary and find two that share the same approximate resistance with a 3rd wire. That wire is the CT.
@hestheMaster
4 жыл бұрын
Amplifiers are very dangerous to work on unless you know what you are doing. Think safety ,safety ,safety. Plug your amp into an isolation transformer while working on one if you need to power it up to test voltages and currents. If after you do power an amp up do not assume the electrolytic capacitors are safe to work on because they can still hold a lethal voltage as well. They must be discharged through a resistor . They can hold a high voltage for hours or even days. Thanks for the biasing output tube video professor Doug! Always something new to learn!
@UncleDoug
4 жыл бұрын
Thank you for your wise advice, HM :)
@danielsaturnino5715
4 жыл бұрын
Still subscribed! Thanks for sharing!
@UncleDoug
4 жыл бұрын
Good to hear, Dan. You're quite welcome.
@hamish93
4 жыл бұрын
Hello, enjoyed the video, in fact, I enjoy all your videos. One thing though, if you have two anodes (plates) tied together, the anode (plate) voltage is going to be the same irrespective of the current flowing through the valves. So I don't quite get your comment on if one tube is worse/better than the other.
@UncleDoug
4 жыл бұрын
You're right, Bill. This has all been explained by a note in the video description.
@stevejeffryes5086
4 жыл бұрын
Would it be effective to pull a tube from each side of the quad output and take readings so that you would detect the dissipation on each individual tube and thus detect any of those 10mA/50mA mismatches?
@UncleDoug
4 жыл бұрын
I think pulling one of the tubes in a pair would change the values for the remaining tube, Steve, which might conceal a disparity.
@qua7771
4 жыл бұрын
Why not have bias meters mounted to the back of the amp with a recessed pot for adjusting.
@UncleDoug
4 жыл бұрын
I guess you could, AR, but you bias only once in a while, and having the bias probe separate allows it to be used on many different amps.
@FMFVeteran
Жыл бұрын
😄😎
@UncleDoug
Жыл бұрын
Thanks :)
@46bovine
4 жыл бұрын
Thanks Uncle Doug. A great video.
@UncleDoug
4 жыл бұрын
Glad you enjoyed it, Bob.
@atwaterkent911
Жыл бұрын
Yes you must keep a hand on the pants probe...at all times...safety first....
@UncleDoug
Жыл бұрын
.....and, like Frankenstein, it may actually be awakened to rise from the dead.
@sootikins
4 жыл бұрын
So how does the Euro Probe deal with cathode bias versus grid bias? Does it measure voltage between plate and cathode, or plate and grid, or is there a switch to tell it which way to measure? Or is it smarter than that, i.e. can it figure out which type of biasing it's looking at by reading voltages and using the lower (I think) one?
@UncleDoug
4 жыл бұрын
If you measure the PV between plate and cathode, you will always be right, Sooti......recall that the cathode is grounded in grid-biasing.
@MegaGuitman
4 жыл бұрын
I was an avionics tech in the army during the Vietnam era and got zapped and felt like I had been kicked in the chest and I ended on my back on the floor.
@UncleDoug
4 жыл бұрын
Amen. It can take a few days to recover from a through-the -chest shock, Jay......if you recover at all.
@kkrekula
3 жыл бұрын
Thanks for the insights, humor and nice choice of songs for strumming on the guitar ;)
@UncleDoug
3 жыл бұрын
The pleasure is ours, Ken :)
@chadcohoon8867
4 жыл бұрын
Thank you very much for the video .. Top shelf info
@UncleDoug
4 жыл бұрын
Glad it was helpful, Chad. Thanks !!
@kubockferre5532
Жыл бұрын
Hi what do you think about cathode bias input with a led and resistor in series and how to calculate this .thanks
@UncleDoug
Жыл бұрын
I have never heard of the concept, Kubock.
@wegert1
4 жыл бұрын
Thanks UD. You too. Great vid as always.
@UncleDoug
4 жыл бұрын
Our pleasure, RSF :)
@SuperSeanXXX
3 жыл бұрын
Oh I forgot to mention I'm running 80% wall voltage on a dual output power transformer
@smeh3929
Жыл бұрын
Дуже дякую вам за відео і чудову інформацію ! 👍👍👍🙂
@UncleDoug
5 ай бұрын
You're welcome. I'm glad you enjoyed it.
@Claymansd
4 жыл бұрын
How could anyone thumbs down this???
@UncleDoug
4 жыл бұрын
I have asked myself this question, Scot, and have come to the conclusion that somewhere in a basement in the mid-West, there must be a lunatic asylum with computer access ;)
@TimHollingworth
5 ай бұрын
I understand the calculations but how do you alter the bias to lower the wattage? I'm assuming you change out the resistor or add a variable resistor? That explanation would be useful to balance the output.
@UncleDoug
5 ай бұрын
Tim, I've posted several other videos on adjustment of bias in all sorts of amps, and a couple videos on how to make the bias adjustable.
@TimHollingworth
5 ай бұрын
@@UncleDoug Thanks Doug, I'll check them out. I'm trying to find a schematic diagram of the Sound City 120 PA 6 channel amp. There are lots for the lead/bass amps but I can't find anything regarding my old amp that I want to refurb. Many thanks for your reply.
@UncleDoug
5 ай бұрын
@@TimHollingworth Good luck on the schematic, Tim.
@ertreri
3 жыл бұрын
super good video. many thanks
@UncleDoug
3 жыл бұрын
You're welcome, E. Glad you enjoyed it.
@mattrogers1946
4 жыл бұрын
Thank you for another informative video.
@UncleDoug
4 жыл бұрын
Our pleasure, Matt.
@gillesswing1423
Жыл бұрын
Uncle Doug, is it possible that you explain how works the triode vs the pentode modes as we can "see" on some power amp (like Marshall ) which are used to to be able to switch between 2 power rates (on JCM900 : 50w and 100w) ? Thanks Uncle Doug (you will be my Santa Claus ! )
@UncleDoug
Жыл бұрын
In a recent video, I highlighted triode/pentode switching capability. To be honest, I think it's way overrated.
@gillesswing1423
Жыл бұрын
@@UncleDoug Thanks a lot. I will search this video.
@remi3741
4 жыл бұрын
very usefull video doug thanks
@UncleDoug
4 жыл бұрын
Glad it was helpful, Remi.
@BAMPSANDPEDALS
3 жыл бұрын
a question about the PD, Uncle Doug. in case of a Princeton Reverb were the 6V6 is grid biased. If you are using the amp in a studio envirment, or at home and the volume knob never exeed number 6. Is it usefull then to bias it 50/60% of the 12W? Greetings Benny
@UncleDoug
3 жыл бұрын
I honestly don't feel that biasing to the 70% max value is necessary for good tone, B&P. What I intend to do is create a video in which a grid-biased amp will be played and recorded at 40%, 50%, 60%, and finally 70% BP.......just to see if there really is any audible difference. If I'm wrong, then it will be evident......but if I'm right, it would resolve the issue, at least for the amp circuit I use for the test.
@BAMPSANDPEDALS
3 жыл бұрын
@@UncleDoug looking forward on that video! Thanks Uncle Doug.
@bobvines00
4 жыл бұрын
Uncle Doug, thank you for this video to clear things up about biasing of output tubes. It is very educational. I've got a few questions, mostly related to this video: 1. When you were explaining cathode & grid biasing @ ~16:48, you said that grid-biased tubes need to be run at ~50-60% of the max plate dissipation (PD) for tube longevity and cathode-biased tubes can be run up to ~90% of the max PD. **If I had a grid-biased amp, but wanted to "get more out of it" and not quickly burn my tubes up, could I rewire it to be cathode-biased without letting the magic smoke out (or otherwise screwing it up) & still get a "good sound" too?** Curious minds want to know! 2. Since PD = PC * PV, is this how amps are rated for their output? Do you simply add up PDs of all output tubes to get a real output rating? Or is the output on the label more "market-speak" than a real number? I can't remember whether or not you've already made a video explaining how an amp's actual output rating is determined vs. what's on the label or paperwork. I apologize if this question isn't well thought out -- I'm trying to think through a migraine right now. :( 3. Now for a nit-pick: Can you change your editing style to not cut off what you are/were saying? You were trying to be very clear with an explanation on placement of voltmeter probes on a cathode-biased tube @06:54 in this video, but cut yourself off mid-sentence/word, defeating the "very clearness" (to make up a term) I think you are aiming for. (You do this fairly often in your videos. I've never made a video and certainly haven't tried to edit one, so there may be a good reason for these cut-off words, but I don't remember watching any other videos on other Channels with similar edit "oopses.") I look forward to your upcoming(?) video on the theory of grid-biasing! You have some of the best & most clear explanations on amp "theory and practice"!
@UncleDoug
4 жыл бұрын
1.) Yes you could convert from grid-biased to cathode-biased. The tone would be different and your output power would probably be reduced. 2.) No, output power is measured in a very different way. See my video explaining how it's done. 3.) The final word clipping occurs far less often in recent videos and is due to a flaw in my editing program that reduces scene length occasionally by eliminating the final fraction of a second, i.e. a 10.86 second scene will be reduced to 10 seconds. I have reduced the problem by simply waiting a second after each scene before turning off the camera. Bottom line, I'm doing the best I can. Please focus on the positive aspects of the videos. I have already posted videos on grid and cathode biasing. Please see my video list.
@bobvines00
4 жыл бұрын
@@UncleDoug Thank you for your answers -- I'll go back and find those videos. I suspected that the clipping was software-related, perhaps I should have figured out a better way to bring it up though. I do focus on the positive aspects of all of your videos (there are virtually no negative aspects to your videos). The nit-pick came about from this particular clipping that sounded like it was working against what your goal was -- the nit-pick wasn't meant to be taken as a negative remark. Thanks again for your thoughtful videos!
@nicewilbur1
4 жыл бұрын
Hey Doug, love the channel - my friend turned me onto it over the weekend.. Hoping I can find a tech in AZ to help build a custom low watt amp from a 1950/51 Magnavox entertainment console amp.. Not sure where to start. thanks for all the videos!! These are great.
@UncleDoug
4 жыл бұрын
Welcome aboard, David. Maybe one of our viewers will step forward to help you out. Best of luck.
@nicewilbur1
4 жыл бұрын
@@UncleDoug it's all I can hope for.. :) I have the two 12" 5-prong plug speakers, too..
@magnusekhall
4 жыл бұрын
I love the more technical videos!
@UncleDoug
4 жыл бұрын
Thanks, Magnus. They aren't as popular as my regular videos, but it's important to have this information on YT as reference material for viewers needing help.
@magnusekhall
4 жыл бұрын
@@UncleDoug To me the technical videos are at least as interesting as the regular ones. I have learned so much from watching your technical videos. I don't think I've seen better videos explaining how electronics with tubes works.
@michaelhager4270
4 жыл бұрын
Hi Uncle Doug, another great video. Thank you. You mentioned the bias probe. If you plugged a bias probe into one of the 4 tubes, would both the tubes on that sides current be read? Hopefully that makes sense? Once again thank you from down under Australia. Your videos are such an incredible resource for the DIY community.
@UncleDoug
4 жыл бұрын
Thanks so much, Michael. Using a bias probe removes all the uncertainty......each tube's PC, PV, and calculated PD are individually tabulated, so you know the operating parameters of all four tubes, not the average of each pair.
@michaelhager4270
4 жыл бұрын
@@UncleDoug Thanks Uncle Doug
@dgemstate5422
4 жыл бұрын
Hey, Uncle Doug. I have a mid 70's Fender Bassman 100. I don't think I have the experience or talent to do maintenance on it. I would like to send the head only to you to go through, and check my amp, and modernize it, etc. Can you let me know if you are able to do this for me? I have a couple of ideas to run by you, that I expect you like. Thank you.
@dgemstate5422
4 жыл бұрын
My email is: scott@clearline systems.com.
@UncleDoug
4 жыл бұрын
Please message me on my FB page: Uncle Doug's Vintage Amps. I am currently swamped with work but may be able to help you in the future.
@SIXSTRING63
4 жыл бұрын
Just an observation, As plate current changes with volume and frequency so does the speaker impedance which will change the reflective impedance that the tube will get. An 8 ohm speaker can go from 2-30+ ohms when pushed. Guys like Dave Friedman say to run a 30 ohm dummy load on an 8 ohm output for running without a cab if you don't have a dedicated reactive dummy load box for recording. My point is, I run my tubes at 65% and have for years and never seem to wear tubes any worse than running colder. I usually try to look for notch distortion on the scope and split the difference. Lee Jackson biases all his amps that way, takes the signal to clipping and backs off to a nice shaped sine wave. If there is crossover distortion he just heats the bias a bit till it is gone and leaves it there. Said in his 40 years of building custom high gain amps and modding amps to the stars that has been his method that gets the best overall tone. Lately I’ve measuring my plate current using the shunt method which is probably the most dangerous using your multimeter in DC Ma mode from plate pin of tube socket to center tap of output transformer while amp is at idle. I have the bias sockets with the one ohm resistor that uses Mv to measure Ma using ohms law. I usually get a higher read off the sockets than I do using a quality Fluke 189 in Ma mode which would make you bias it colder from that higher reading. Using this method I want a meter with good front end protection and an accurate current shunt. Your method of measuring the resistance from center tap to plate is great advice to people new to this game of lethal voltage. I will have compare readings from the resistance reading to the shunt reading. They should be very close. I don’t think I’d try the shunt method with a free Harbor Freight meter and cheap leads. Might have a smoking melted plastic blob. 😲 Just my Flukes, Tektronix or Brymen meters for that test. Here’s a cool article with charts showing the wide swing of impedance a speaker will go through with frequency changes. audiojudgement.com/speaker-impedance-curve-explained/
@UncleDoug
4 жыл бұрын
Thanks for all the helpful info, 6S.
@SIXSTRING63
4 жыл бұрын
Uncle Doug Just some tidbits of info. You are one of the best techs on here and I never miss a video and have watched your whole catalog of videos! Especially in the long boring winter months of the northeast 🙂. I watch tech videos much more than any TV and have used your methods and advice in many amp rebuilds and repairs. Your concern for peoples safety is priceless. When guys like Bruce Egnater mention you as the guy to watch if they’re getting into amp repair that is quite a compliment. I read a lot of books, watch your videos, Lee Jackson, Dave Friedman, D-Lab, Joe Smith(probably the smartest EE that puts videos on here), W2aew...............thought I’d share some thoughts and ideas I have wondered about concerning constant impedance fluctuations and what it does to tubes and transformers. Subtle changes in speaker wiring can have such a profound change in amp tone, feel and performance, parallel wire two 8 ohm speakers and then wire same two in series. Quite a difference in frequency response and tonal quality. I have the tone chasing addiction as do most gigging guitarist. I have always been an amp overdrive guy so I learned how do my own amp repair and mods. Lately after playing many vintage Fender amps and how great the react with good overdrive pedals. Easier to change out pedals than mod a front end of a high gain amp. Love Fender clean tones, nothing like it. I guess that’s why they are great pedal platforms. Getting too old to be an Eric Johnson tone chaser taking out 4 amps like plexi’s, twin’s, old echoplex’s and fuzzface pedals. Keep up the great videos Doug! There is hope for this country if you pass that knowledge on to just 1 or 2 out of every hundred who watched and learned. I try to do the same with my modest knowledge of amps and my 45 years of guitar playing, 40 of them have been gigging years. I do lessons at the same store I do repair work for.
@UncleDoug
4 жыл бұрын
@@SIXSTRING63 Wow,, thanks so much for all your interesting and informative comments, 6S. It's always great to hear from you.
@phonotical
4 жыл бұрын
note to self, earth metal stuff...
@alexkatsaros6180
4 жыл бұрын
I’ve been ready Uncle Doug!
@UncleDoug
4 жыл бұрын
Good to hear, Alex :)
@stephenmonike1906
10 күн бұрын
Doug how do you figure the bias voltage from that 30ma current flow,I mean what would 30ma be in voltage
@UncleDoug
10 күн бұрын
It is all explained in the video, Stephen.
@stephenmonike1906
8 күн бұрын
Ok, I'll go back over it again,
@stephenmonike1906
8 күн бұрын
I almost forgot do I have to have a DC, Current meter to check my current or will the AC current setting work
@UncleDoug
7 күн бұрын
@@stephenmonike1906 Since the current is calculated based on voltage drop across a known resistance, you will need a DC voltmeter.
@gerrabath
2 жыл бұрын
Doug. Just to clarify at 6:53 your saying the negative probe goes directly onto the cathode tube pin?
@UncleDoug
2 жыл бұрын
Yes. I apologize for the early scene cutoff by my editing program.
@gerrabath
2 жыл бұрын
@@UncleDoug Thanks Doug. Your reply and clarification is much appreciated.
@gillesswing1423
Жыл бұрын
HI Uncle Doug At 14:32, I do not understand how the two plates voltages can be different since the two plates are connected to the same potential voltage (there are wired at the same point)...?
@UncleDoug
Жыл бұрын
I understand your confusion, Gilles. The main difference between the conditions in each tube will be seen in the Plate Current......not the PV.
@gillesswing1423
Жыл бұрын
@@UncleDoug Thanks a lot ( I am relieved :) )
@wayshot
4 жыл бұрын
Great video :-) Regarding cathode-biased PP amps: Is there any pros and cons on shared vs separate cathode resistors/bypass caps for the power tubes?
@UncleDoug
4 жыл бұрын
Thanks. Good question, Asle. It seems like all the manufacturers make the cathodes share a resistor and a single bypass cap.....probably to save money. With separate resistors, you can exactly match the bias of two output tubes, which would be a nice capability.
@wayshot
4 жыл бұрын
@@UncleDoug Noticed that too. Seems like almost all guitar amps share a resistor and cap, while they're usually separate on PA and hi-fi amps. Separate resistors/caps make it easier to check the bias on each tube. Also, the remaining tube(s) will not melt down if one tube fails. Our kitty Minni sends regards to KC, Jack and Ollie, by the way :-)
@jayster.k.wiseguy
4 жыл бұрын
am so honored, sir~....jayster~
@UncleDoug
4 жыл бұрын
I thought your painting really looked great in the video, Jay. Just wait until Twin Reverb video in a week or so. Both the paintings and you get recognition.
@michaelbutler2312
4 жыл бұрын
another great video. thank you!
@UncleDoug
4 жыл бұрын
My pleasure, Mike.
@cacornett58
4 жыл бұрын
Question, if you accidently touch the B+, with one hand, while the other is in your pocket, will it be as bad as the chassis shock? I know probably deiends on how good you are grounded to the floor, and it's going to be very nasty, but less chance of fatal or not?
@UncleDoug
4 жыл бұрын
The "beauty" of DC (B+) is that it has no affinity for earth grounding. All it "wants" to do is get back to its source, which is usually through a chassis ground. If you touch DC with one finger, nothing happens. If you touch DC with one finger while your other hand is on the chassis (ground), it completes a circuit through your body and might kill you.
@cacornett58
4 жыл бұрын
@@UncleDoug Thanks so much, and keep those videos coming. I have learned many things from your videos, do you have a video on long tailed differential circuit in amplifiers? How they work, why its part of the circuit, etc?
@kirkgreenman1386
4 жыл бұрын
Awesome! Going to watch that again.
@UncleDoug
4 жыл бұрын
Things generally make more sense the second time around, Kirk :)
@HDDog2
4 жыл бұрын
Shouldn't that be 6L6's ??
@UncleDoug
4 жыл бұрын
I switched tubes in the middle of the story.....sorry for any confusion.
@sharkskinboy
2 жыл бұрын
Hi Doug, just wondering, to be able to check each tube for correct bias rather than just checking each pair and hoping for the best, can you do a bias measurement with say the outer tubes removed, and then repeat with the inner tubes removed? So you're in effect checking bias on output pairs twice. Thanks for the great video!
@UncleDoug
2 жыл бұрын
No need, SB. All the OPT "sees" is the push from one pair and the pull from the other. The tubes don't function as individuals.....only as pairs.
@sharkskinboy
2 жыл бұрын
@@UncleDoug I see, thanks for your reply!
@steverollinson6906
4 жыл бұрын
I do wish you posted a Eurotubes probe owners version too! I think most of your fans have bought them and would love a tutorial!
@UncleDoug
4 жыл бұрын
It's so easy with the Eurotubes probes that you really don't need a video, Steve. Just march down the line and get measurements from each tube.
@steverollinson6906
4 жыл бұрын
@@UncleDoug Thanks!
@Mark70609
5 ай бұрын
I didn’t understand what you were talking about in regard to knowing if the valves were matched. If you have all the valves in and you are measuring the valves on one side of the output transformer. The voltage of both the plates would be the same. So there is no way you would know if one valve is drawing more current.
@UncleDoug
5 ай бұрын
The term "matching" refers to the amount of current each tube draws relative to the others. This can be measured best with a Eurotubes bias probe, but there are other methods. In a "matched" tube set, they arrive all drawing the same amount of current.
@Mark70609
5 ай бұрын
@@UncleDoug I have hung a 1 ohm 1% resistor in either plate or cathode of the output valves. I recently got the TAD bias master, it’s good but it would be better if it displays the plate voltage.
@UncleDoug
5 ай бұрын
@@Mark70609 Plate voltage is easy to measure.....or you can get a Eurotubes probe.
@Echo_III
2 жыл бұрын
Uncle Doug, what if there is a resistor between plate and transformer? I have 47 ohm resistors. Should I measure the voltage drop, resistance and plate voltage ON plate or ON transformer tap?
@UncleDoug
2 жыл бұрын
Not knowing the brand or seeing a schematic, I am not familiar with 47 Ohm plate resistors. Are you sure they are not 470 Ohm screen resistors? Regardless, the current calculation is Voltage Drop divided by TOTAL resistance.....so you would measure from OPT CT to tube plate to get total resistance.
@Echo_III
2 жыл бұрын
@@UncleDoug so the plate voltage should be also taken directly from the pin, not from the output tap, correct? It is a ultralinear amplifier with four 6550 tubes.
@UncleDoug
2 жыл бұрын
@@Echo_III If the cathodes are grounded, plate voltage is taken between the tube socket's plate pin and chassis ground
@_Ramen-Vac_
4 жыл бұрын
My compliments. 1 hand,,, just amputate ? lol
@UncleDoug
4 жыл бұрын
That would be a bit extreme, especially since you could still touch the chassis with your stump
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