Tube Amplifier Repair, and what to look for.

[@RobertsAutomotive]

Maas Rowe Carillons Is the company and they turned 100 years old this year. My father worked there his entire working career, met my mom there, and I got my first job there as well, tuning chime tubes... Thanks for the cool videos, you earned another sub!

[@markj4066]

As a former broadcast engineer this was a walk back in history for me. Very well done and appreciated.

[@mikesradiorepair]

I love working on old tube amplifiers. Can't beat the make it simple stupid design. One thing I would note when replacing power cords is watch polarity. Modern power cords and outlets are polarized. As you are aware some radios and TV's ran a hot chassis. Back in the day you had a 50-50 chance when plugging in something that you could be attaching the chassis to neutral or hot. When replacing the cord always be sure the neutral side of the cord is attached to the neutral side of the cord. Just thought I would mention that for the viewers.

[@petroldevo9934]

Good point ! I lived in this dumpy apartment years ago and had friends over all the time. One day I went to wash my hands and grab a beer from the fridge well aparently touching the metal fridge door handle and the sink faucet were neutral/hot. One friend found out the hard way getting a beer even after the warning.

[@electrolyticmaster8396]

I destroyed a TV back in the sixties .. because of polarity reversal.

[@PeopleAlreadyDidThis]

Just found your channel, subscribed. I love tube equipment. In 1973, aged 13, I built a preamp and power amp from the schematics in the 1963 RCA Receiving Tube Manual. Remarkably, it worked “out of the box.” Still have it! I learned that much of the spacious component placement came from following the recommended tube spacing distances in the power amp. Commercial amps often crowded the tubes to save cost. I also learned about touching 250V B+ circuits when I slipped one day. Never again. The output transformer cost $60 back then at the local supply house. It weighs as much as a small anvil. Wish I had a box full of them.

[@electricboyo]

When I was in high school a friend of my parents who was a ham radio operator gave me a RCA receiving tube manual and an ARRL ham radio handbook. Over time I read them from cover to cover. Plenty of these old books are still around and well worth having for everyone who is interested in vacuum tube circuitry. Also many have been scanned and can be downloaded for free.

[@foolscrowstudio]

i love all your videos, i listen to em when im teching, as a self taught tech, Ive come to find Im most impressed by gear that has lasted the longest in service without needing repair even over performance and "specs" , which really comes down to craftsmanship and engineering over cost-cutting or the latest trends.

[@steelcity321pb6]

It will be an immense honour to be given a tour round your Broadcast transmitters. Another informative, and very well crafted video: thank you Paul. Phil.

[@MrCarlsonsLab]

Thanks for your input Phil!

[@johns9918]

I agree. I was a broadcast engineer back in the early '60s.

[@ianbutler1983]

"I have a couple of broadcast transmitters..." Now there is a phrase you don't hear on many youtube channels. Thanks Paul, yours is my favorite channel.

[@MrCarlsonsLab]

Thanks Ian! I'm glad you're enjoying the channel!

[@SuEnRoD]

Thank you for this video. You brought back a memory/question from my youth (54 now) that I never answered. I remember thinking our church bell sounded the same EVERY Sunday but never knew why. Now it makes sense. Carillon amplifier. Now I know.

[@rameshbabu1963]

sir, when comes to vintage electronic stuff you are the master your narration touches the history as well .. thats amazing

[@MrCarlsonsLab]

Thanks for your kind comment!

[@Dzonemp]

I started out working on tube TVs when I was a Kid. My Mom had found some how to books from the 50's and I used them to help me repair TVs. The problem with that is every time I turned around somebody wanted to give their old broken TV. I quickly ran out of room for them, but I did get pretty good at cannibalizing parts to repair other TVs. Thanks for the great video!

[@MrXapheth]

My knowledge about electronics is absolutely nothing! But watching this channel I learn a lot! Awesome channel!

[@keithlincicum3691]

Great, informative video Mr.C. I have a vacuum tube amp. that I built as a Knight Kit KG 240. In 9th grade I had finished my assigned wood shop projects, so the teacher allowed me to design my own with 2 months left. All mom had to play her records on was a dirt-cheap Wards plastic portable. Dad got Allied catalogs and in the sale insert they offered an amp kit, 2- 8" speakers and a record changer for I think $59.99. I first showed it to mom, and she then to dad. The battle was on. Money wasn't a factor, but his lack of faith in me was well versed. He caved to my surprise and we sent off for it. Mr. Symington entered it in the Spokane Amateur Woodworkers fair and I won 5th place. I was never so careful assembling anything as that amp because I knew I'd never hear the end of it if I made a mistake. I finished it while they were out shopping, and when they came in the house I had the amp, speakers and changer laid out on my bed blasting away with one of mom's favorite records. She was all smiles but the old man...... When it was all together she enjoyed it for many years. Now I have severe non-military PTSD so it's very difficult to follow your tips. But I'd like to see the 240 glow and make music again after 53 years. Thanks and take care, Keith L.

[@johnnytacokleinschmidt515]

Great story. You did a really nice thing and have a great memory for it. Dads were quite stoic back then... You're the adult now. It's up to you. God Bless!

[@TheRudydog1]

To all who follow Mr Carlson's videos this man really knows his electronics, both vacuum tube and solid state! I recently acquired a very clean Maas Power Amplifier so I especially enjoyed the history on this amplifier. I was also surprised to find so few components in the Maas but sometimes simple on an audio amplifier means less to get in the way of the amplified signals.

[@alexandermarhefka1887]

Doing repair and restauration work on vintage tube gear since more than four decades I endorse everything said and demonstrated in this excellent educational video! IMHO only one minor aspect was not mentioned and this is the deterioration of carbon (composite) resistors over time. The higher the value, especially above appr. 100kOhm, and the higher the voltage drop over these resistors, the more likely their value has increased above the usual 10% tolerance range. Deviations of more than 100% are no rarity. Recently I was called to a Hammond E-100 (mfd. around 1965) with a weak vibrato channel. The plate resistor of an EF86/6CF8 had changed its value from nominal 220kOhm to 1.4MOhm! So I usually check all resistors if I have older gear on the bench for restauration. Only inductors seem to be quite stable over decades, but capacitors and resistors are definitely prone to leakage and value changes with time. Keep on making your splendid teaching videos, Paul. You have universal knowlegde and experience and great teaching abilities! Even for an old hand like me It is great pleasure to watch your stuff (e.g. the Yaesu FT-1000 rep&mod) and to learn about some details. Best regards Alex

[@mangentle7618]

I am a newbie for building tube amplifier. It is extremely hard to find good tutorials/ references in the Asian world even i am in Hong Kong. Thank you for your kind and superior explanation Mr. Carlson, and I clicked "confirm to join" on Patreon of course. Let's get started!

[@guidoburgalassi1531]

Ho vissuto di pane e valvole tutta la mia gioventù e ora che sono vecchio le adoro sempre e ne ho una bella collezione. Ho costruito molti amplificatori con le mitiche 6V6. Ho tutti i bollettini della geloso dai quali ho attinto parecchi schemi in quanto internet non esisteva. Complimenti per il tuo canale che mi fa sognare.

[@h3tv]

Thank you Paul, I have watched numerous vids you have done on tube radios and amplifiers and tube test equipment and how to bring them back to ;their former glory or better. It has helped me as I have recently brought back to life an approx. 1936-38 Silvertone / Mission Bell 41AW radio that I bought at a Saturday night farmers auction in 1967.

[@MrCarlsonsLab]

Your welcome Ron!

[@redemptusrenatus5336]

Tiny Grief capacitors... I love it! Reminds me of Windows when Microsoft came out with it's new "Plug and Play" technology and we'd call it, "Plug and Pray" instead :P

[@MrCarlsonsLab]

LOL!

[@rimmersbryggeri]

Microsoft used to work together with Ericsson so when Ericsson announced their Bluetooth technology Microsoft were fast to counter it with their Blue-Screen technology.

[@faxcapper]

I was in New York's Time Square about 10 years ago and one of the huge video screen had a massive BSOD Blue Screen Of Death. Wonderful adverting for Microsoft. :-)

[@bekiil]

hehe, yeah I remember that. ISDN was "troublesome" 😅

[@ed731pdh]

ISDN - "I Scramble Data Nausiatingly". :)

[@bloguetronica]

Very insightful video! Tube technology is actually very interesting. I still have much to learn, but watching your videos gives me that opportunity. Thanks once again, Paul, for another great and well explained video!

[@ViolonistaCanhoto]

I just stumbled onto this video. Fascinating, and beautifully done. Mr. Carlson, you are a gifted teacher. I'll become a patron. Thank you.

[@MrCarlsonsLab]

Thanks! I look forward to seeing you there.

[@charlescartwright6367]

Aloha- I cut my teeth with the vacuum tubes as transistors were too noisy and would never be able to handle any power or high speed transit switching. So much for the wisdom of the day! I enjoy your channel as I enjoyed the component level repair of the electronics I was working on. I always said I would retire when we quit component level repair, and I did, but I also never thought I would see the day I could sneeze and blow away all my spare parts. Modern is ok as my ham radio gear is more stable and more accurate than some of the test equipment we used. Thank you [Mahalo] for your time and work reviewing the older technology. Aloha No.

[@MrCarlsonsLab]

Glad you're enjoying the video's Charles! Thanks for taking the time to write.

[@tadonplane8265]

You sent me on a learning path I never expected...what’s a carillon? So I looked it up. A carillon is a percussion musical instrument consisting of at least 23 cast bronze bells, any less than that and it’s a chime. Some are played mechanically but traditional ones are played manually via a large keyboard and footboard by a carillonneur. The largest one in the world is in the Palace of Mafra in Portugal and has 120 bells. Most carillons are installed in bell towers but there are portable ones. Your MAAS 50 may have amplified pre-recorded bell music, but it may also have amplified live emulated bell music played on a keyboard. The bell sound signal was created by striking various length tuned metal rods or tubular bells via solenoid driven hammers and picked up with a mic or magnetic pickup. Often the church organ keyboard could be set to play the carillon. The German name for a carillon is a glockenspiel.

[@abeleballestri612]

Thanks for the interesting video I just admired and I must say it was a real surprise to see such a wonderful amplifier that can work for hours uninterrupted way doing its job. Looking forward of seeing you again ,thanks for the time you have given us.

[@fortj3]

How can anyone give a thumbs down to any Mr Carlson's Lab video? Yet another great video, Mr Carlson. I'm addicted to your videos. I don't watch them in any kind of order. I'm looking at a Newcomb D-10 and thinking about converting it into a guitar/bass/harmonica amp. Any tips you can give me?

[@JoseRochaMicroondas]

um espetáculo de equipamento que coisa linda

[@SteveGunnfl]

You are a breath of much needed air - the commitment to want to do it well and do it right - something that's sadly becoming a rarity in today's disposable society.. My wife would never let me have that much test gear buy hey I can dream :) Thanks again, I like watching something that is the total opposite of "10 quick fixes". videos.

[@gettingpast4391]

Great video, loved the leakage demo with the magic eye. Great example of how useful these old testers still are. Subscribed!

[@MrCarlsonsLab]

Thanks Tom!

[@bryantwhittaker4163]

I enjoy watching your videos because they're relaxing and you learn something when it comes to electronic repair and care of electronic devices

[@cuban9splat]

Another big YES to the question about your transmitter tour idea! Well done video as always. Thank you.

[@BrokebackBob]

Your vids are spectacular and I love that you use Heath products in your lab.

[@MrCarlsonsLab]

Thanks Bob!

[@gibbyrockerhunter]

God I love your channel. I am (hopefully) picking up my first tube amp tomorrow. When I got the good news my first thought was to see what you had to say on the subject. Thanks for all the awesome content.

[@pradolover]

definitely interested in the radio transmitter tour!

[@matthijshebly]

This channel is a true gem...

[@borisromanoff4244]

a nice idea showing your transmitters too!

[@alltopnotch235]

Firstly another great video I for one would love a tour of a broadcast transmitter

[@hugoradiorepairsmartel514]

Very good video Paul!! I would love to see the inside of an old broadcast transmiter!! Take care, Hugo

[@nmbdk4955]

Great little thing! It would be nice to go over the schematic and get an introduction/analyzation of how it actually works :)

[@strangersound]

Check out "Uncle Doug" on KZbin. He has some great videos covering tube amp circuit design and signal flow, etc.

[@nmbdk4955]

Already subscribed ;)

[@jamesclawson9156]

Old tech here, love old gear and other stuff ,, enjoy all , 2 thumbs up

[@MrCarlsonsLab]

Thanks 👍

[@W1RMD]

YES!!! I want to see broadcash transmitters! Excellent video. Very basic yet very informative. Also, have you noticed that the metal can crapacitors tend to last WAY longer than other types? I've NEVER had to change one. Even in 60 year old equipment. The exception being the salt and pepper shaker style copper can style in my Philco model 70. There was loose stuff inside that came out the holes on top. I just disconnected it, polished it up and put some small electrolytic craps underneath. A coat of clear coat and the copper still looks new 25+ years after restoration! 73's de w1rmd.

[@tonygriffiths2485]

Thanks am having a great time seeing the older videos. Very enjoyable and always something to learn.

[@shyleshsrinivasan5092]

Thanks a lot sir ! Please put more of these videos !

[@markschmitt5550]

I just aquired a Maas model 50 and a 500 in pristine condition. A quick look, I was able to see a rough picture in my mind of the 50's circuitry. I'm amazed that there isn't a schematic on the internet, as popular as these were. It looks like I'll have to pencil one out. It appears that the 50 will require a preamp, too. I may remove the two triodes and wire in two 6sn7's. Part of me wants to politely convert this old girl into a sweet guitar amp. The 6v6 screen regulator in a novel idea; something that a few 1k resistors could easily do, opening up another tube socket. Now for the best part... the serial number on mine is 80!?! The audio chain caps in mine are ceramic, and not the axials that you have in yours.

[@MrCarlsonsLab]

I have a complete re-design of this amp on Patreon with schematics, and a lot of other information.

[@jimadams2473]

Another very cool on vintage gear. Nice work. And, yes, it would be great to see inside a transmitter that you can literally stand in!!!! Thanks for the GREAT vids.

[@ka0kuj599]

Excellent info. Paul We'll take the big transmitter tour too. 73, Scott W0KU.

[@johnbellas490]

Paul this was interesting Video, in that it reminded me of when I had bought from P&T Surplus in Kingston N.Y. USA a Bell Tower Carilon tape system WITH the power amp much like you have there! The tape was contained in quite LARGE tape cartridges about three times the size of the old cartridges used in broadcast studios!! the player could hold 12 cartridges that held the hourly bell chimes, then there was another player unit that held 3 cartridges I think these were for any public announcements by the church OR civil authorities. I had rebuilt the system had it for a while then sold it to another church that had built a new facility about 10 miles down the road from me!

[@MrCarlsonsLab]

Great story John, Thanks for sharing that!

[@scottweisel3640]

When I was a teenager I was given a tube stereo (15W/channel) and thought I would “improve” it by changing a lot of the the point-to-point wiring to PC board which meant designing the PC board. I bought the etching kit from Radio Shack and completed that phase of the project but never finished. The amp died from unknown causes and I shelved everything. I now understand there is a reason why the tubes and components are laid out the way they are on a tube amp, and I would have created a lot of problems had I “succeeded” by completing the project. One feature of this amp that I remember was that it used a full bridge rectifier with four power diodes, rather than a tube rectifier.

[@dylanheadrick3789]

Definitely exactly the video I was looking for as well as the tube troubleshooting tips vid. I've got a 1957 VM phonograph/changer that is non-functioning as well as a 69 Hammond H-182 organ with low output volume. I've done the obligatory electrolytic/paper cap replacement in both, but the phonograph is still silent. None of the tubes are lit but I can hear a very faint hum from the speakers. The chassis is buried in the body which makes it quite difficult to get to its underside while keeping it connected to the speakers. After watching your troubleshooting tips, I'm definitely going to be checking the heater voltages as a first test to see if i'm in need of a new transformer. On the organ, going through the service manual, the speaker RMS voltages are supposed to read about 10.5 Vrms, however mine seem to be at about 2 Vrms at maximum volume. After watching the same video, I'm assuming it could be the bias resistors off of the cathode or the plate resistor which could be causing a small differential in the voltages. Again, all electrolytic and paper caps have been replaced, but it only helped so much. I swear I learned more about tube amp theory and diagnosing in your two videos than I have in years of fiddling with them.

[@OsmosisHD]

I have an Lafayette tube amp (SE, Class A) from 1967 It hasn't had any maintenance and was sitting there collecting dust for +10 years , till I bought it from at a garage sale. The only thing I did, was replace all the caps, new tubes, new potentiometer and added a bleeder resistor in the supply & cleaned the unit up a few hours later...It worked like a charm! As if it was brand spanking new They don't make stuff like that anymore sadly, build to last.

[@richardmouton9883]

i really like your videos. i never found a person where i live that could teach or learn from. tv repair/ audio is not being trained to new people.

[@MrCarlsonsLab]

Thanks Richard!

[@guitarpoetone1]

Hi I really injoy your teaching methods your very clear and explain how everything works alone and together visually the art of the inside off the amplifier is beautiful to me thank you for spending your time and showing us your craft an information...

[@oldestgamer]

"some form of a tech"... I LOVE it! There are so many "some form of a tech" that I have seen here on youtube and out in the world with NO idea of what they are doing! Love that comment!

[@emilalmberg1096]

Thank you for this video! Now you have to show us how we build our own leakage meter ...

[@chrischwaz7788]

Question are the patreons a program of access to pre recorded video lessons or for weekly video lessons because I work crazy hours so pre recorded would be great and then I can do the lesson and get some learning In because learning electronics and tube amps repair is just a hobby for me as I am a car mechanic and that’s what I do for a living

[@MrCarlsonsLab]

All the video's (Over 150 on Patreon at the time of my response to you,) are pre-recorded, and can be watched at any time as long as you are a Patron.

[@04jkv]

Thank you for always posting these videos they are always interesting to watch.

[@CVD-di1xn]

Back in the day, I grew up on building tube amplifiers like these. I started with a blank aluminum chassis, punched the holes and did all the wiring. I guess I'm old .... funny, I don't feel old.

[@K7AGE]

Your capacitor stock must be amazing. Seems like every repair project you change out all the caps. It would be interesting to spend a few minutes describing the parts that you stock and how you decide what to stock.

[@Satchmoeddie]

You should see mine..... When Capital went out of business, I was buying old caps by the pound, 100 pounds at a time, and spent weeks and months, checking & sorting. Then I did some reforming, but if they don't start to show progress fast, they get chucked.

[@fernandocoutinho6661]

Dear Carlson, Thank you for your video and knowledge sharing. About a year ago I purchased a Luxman MQ-88uC and really like the sound but I have experienced one problem that is distressing me...suddenly there's no sound from the left channel. In one year of intense use it has now happened four times. I am using a single source connected directly to the Variable input and after turning the volume down and up a few times the sound eventually comes and no more issues for a few months. Since it works well most of the time and I can't replicate the problem it feels awkward to send it to repair service. On the other hand it is very disappointing that such an expensive amplifier has this kind of issues. I changed the driving tubes (both ECC83 and ECC82) to NOS mullard after experiencing the problem the first three times, I had hopes this could solve the problem but it happened again. I have checked the bias current and all seems fine, reading near 480mV in all tubes. Should I worry about thins? Any suggestions would be much appreciated. Best regards.

[@Erzahler]

I just subscribed to your channel! That was a very interesting subject you just covered, and the way you explain everything makes it very easy to understand. I do like the older tube equipment, especially those with the point-to-point wiring. Everything is laid out in a logical manner and is much less complicated that those with circuit boards. Plus, the older tube stuff, if maintained properly (or sometimes not maintained at all!) will last for years! 70+ years for tube gear as opposed to how few number of years for a transistorized equivalent? No contest! If that same amplifier had transistors in it and water (or bird "squirt" got in there), bye-bye transistor! I also liked your cap tester with the eye tube in it. Reminds me of those "tuning eye" receivers which were popular back in the day. My grandmother had one, I think it was a Zenith, an early FM receiver with a center-channel tuning eye. It was one of those models which was manufactured very soon after the FM broadcast band was moved to where it is now. I will just stick to the phrase, "If it doesn't glow, it ain't real!" Thanks and 73! de NØJAA.

[@MrCarlsonsLab]

Welcome!

[@Equiluxe1]

Back in the early 1960's when at school I was taught by an old ex military radio man who by then was repairing TV's that the first thing to check was the switches and pot's then the resistors then valves and capacitors were the last thing to go wrong. Certainly in a lot of the old stuff I was playing around with resistors were cracked and cooked with heat and capacitors were rarely bad. I fixed many a radio that had noisy resistors back then, most of what I had to play with was from the 1920' and 30's. At what time did capacitors start to be the main culprit and resistors hardly ever fail as that appears to be the case these-days.

[@richardlitwin4046]

Yes I'd be fascinated to see the inside of a broadcast transmitter. Thank you very much.

[@eliduttman315]

Mr. Carlson's warning about lethal voltage is spot on. An old "chestnut" says work with 1 hand in a pocket. You can modify the "chestnut" to state or wrapped around your belt, at the small of your back. The point is not to have a shock pass through your heart. Mr. C. are those coupling caps. really PIO or are they waxed paper? Hermetically sealed PIO caps., like the available Soviet surplus K40s or OS "Vitamin Q", seem to stand up well to time's ravages. Are you planning to use 2X 6SN7s in Williamson style circuitry? Eli D.

[@Erzahler]

+hawkturkey: The classic flyback transformer! There was a running joke back in the day. Q: Why are they called flyback transformers? A: Because when you touch one, you fly back! 😄

[@joedebono4012]

Hi really interested in the stuff there’s a lot to learn and it’s good to have somebody giving you some tips you can even save your life who is working on stuff like this Just goes to show sometimes you can’t be too careful

[@pneumatic00]

As bulky, heavy and primitive as they are, I doubt will ever get over my love for old tube amps like those. I too stumbled on a guy who was selling his whole garage full of electronic stuff, mostly from WW2-50's, and in that pile were 32 NOS JAN Sylvania 6L6GA tubes. Sweet. In cartons, though the cardboard would literally crumble if you touched it. So, I built a tube matcher to see if I could gather sort-of matched pairs. Apply the same conditions to two tubes and with two identical panel meters read the cathode currents. I was amazed; very few pairs could be matched closer than 2-3 mils and the readings ranged from 23 to 45 ma. They were all over the place. They all worked but it's as if they were different tube types.

[@csj9619]

I really like point-to-point wired electronics. When a modern solid-state amp fails, it's often more cost-effective to replace it rather than have it repaired. (Unless one does the repair work oneself)

[@garydrumm2879]

Nice, and very thorough as usual. Thank you

[@rubusroo68]

That was great, thank you. I wonder how many are still sitting forgotten in a dark dusty corner.

[@freespuddy]

Yes to looking inside a transmitter.

[@audiotechlabs4650]

Fantastic video! I cannot say enough! You might have explained the reason for more than one rectifier tube. Honest, these are great! Thankz

[@coreyprocyk9078]

Love those 6L6Gs they look great!

[@KarlsLabReport]

Thank you for the good info!! Have been working on restoring some vintage ham radio equipment that belonged to my dad. There is some home-built audio stuff he had, too, that I plan to do at some point. VERY useful information for someone like me who grew up working on solid state stuff. THANKS!

[@JerryEricsson]

Hate to ask an off topic question, but I guess I will just go ahead and do so; I have a Kenwood TM 241A 2 meter mobile transceiver, picked it up off Ebay last year, fellow said it worked great when he last used it. I got my ticket last May but didn't get a chance to hook the unit up till November, and then found that the microphone, the one with the on-board keypad would not key up the set, in fact it acts as though it is getting no power. I hooked it up just before we left South Dakota for Arizona in our motor home, it is mounted in that rig. So after getting to Arizona, I messed with it a bit and finally gave up and ordered the cheap microphone, the one with no keypad. That one will key up the radio, and I can talk back and forth to my two 2 meter hand held units, however I have yet to make contact with any other person, and can't seem to hit any of the local repeaters. At any rate, I guess my question is, is there a fuse in the transceiver that sends the power to the microphone that would cause the big microphone to not work but allow the smaller microphone to key up the set?

[@alimaleki217]

Another great video! I decided to see if I could find one of these. I did, but nothing like the ones in the video. Model 40 (if I recall) and it was basically being held together by rust and electrical tape!

[@TheSpacefanric]

These look very similar to some Australian made valve amps I found at a garage sale. Looking to restore them too

[@vinylhound43]

Yes to the vintage transmitter tour, please. Thanks for this video.

[@nicwilson89]

I really wanna convert one of these into a guitar amplifier. I've got a beautiful old metal 'Ever Ready' radio chassis from the early 40s that came empty that has a nice view inside from the front that I'm going to build a tube guitar amp in to, whether from scratch or modified something else :)

[@DoRC]

For point to point that is super clean

[@AnujArya_Curious]

Another proof that the old age electronics were so good.

[@rustycalvera977]

good video......what an impressive lab....you need a good wide angled lens to capture it all.

[@joedebono4012]

Yeah cheers excellent diagnostic

[@TheRadioShop]

Thanks Paul for the tour and explanation on this amplifier. The simplicity of the circuit is amazing. What model is your capacitor tester? I have the IT-28 and it is laid out the same just different colors. Enjoyed it Paul.

[@MrCarlsonsLab]

Hi Buddy. Your tester is pretty much the same, just a different color. This is the IT-11. Thanks for stopping by!

[@78awhite]

+Mr Carlson's Lab I am interested in the eye tube overload and volume indicator as seen in the Maas Rowe 500a. Do you happen to have one of these and can you explain visual indicator circuits in audio amps like this? I have tried to find a schematic for the 500a without success. Thanks for your videos, I always learn something:)

[@matthewf1979]

That is a beautiful layout!

[@joedebono4012]

Hey I was wondering could you get and orange amp or or a Marshall amp and head and add more tubes A bit of an increased

[@radioengineering8247]

Great vid, very informative! YES please to some videos on big AM and FM transmitters that use tubes as finals. Please make them as in-depth as possible including info on how to set them up, fault-finding and general operating tips. Thanks!

[@TRXLab]

finally I was able to manage to watch a great video Paul. Never heard before about Bell amplifiers...Thanks for sharing. Take care

[@leroygrimaldo4314]

GREAT VIDEO FROM NASA.

[@bucyruserie1211]

I really enjoyed watching this video and the "history" stories as well, very interesting. I couldn't agree more about the power cord, a 3-wire cord just doesn't look right on vintage equipment. The Ground or 3rd wire just ties in at the panel to the neutral (white) wire anyway.. I do however always use a polarized plug for safety :) Take care, Tom

[@MrCarlsonsLab]

Glad you enjoyed Tom!

[@vorkev1]

never hurd the turm convection cooling but the way you describe it and what I see looks and sounds like adaptive cooling or thermal draw cooling

[@CryptToneMusic]

Man I would love to find cool old stuff like this. I usually only come across very dilapidated AA5 or other similarly sketchy radios haha.

[@josephf151]

Great video as always, and a big YES to the transmitter tour idea. If it is such a large transmitter (I believe you showed the outside of it in an early video) what main power tubes is it running? 833As or 833Cs?

[@MrCarlsonsLab]

Hi Joseph. This version has a pair of 810's modulating a pair of 810's.

[@josephf151]

Thank you for the reply. I have little knowledge of 810s, that sounds like it would be a great video.

[@stevedoubleu99B]

Very interesting video Paul (yet again), and yes I would like to see inside a broadcast transmitter.

[@electrolyticmaster8396]

You mentioned using these amps to listen to music. What kind of audio Fidelity do your get from that?

[@uscaremealotyt]

Very interesting...thank you.

[@rondobondo6600]

That is an amazing amplifier

[@graemebrumfitt6668]

As always Paul another great bit of education thank you. Regards G

[@MrCarlsonsLab]

You're welcome Graeme!

[@smallenginedude71]

the story you told about the somewhat damage resistor is a teastament to the quality of those amplifiers!

[@waynecarlson3736]

Always great to learn something new. Thank You

[@JulianA-tr6pt]

Incredible! It's crazy to think that they were run nonstop.

[@AF6LJSue]

Would love to see the old broadcast transmitters.

[@arthurcooper7031]

I love all your videos you are the greatest thanks for all your videos .

[@MrCarlsonsLab]

You're welcome Arthur!