MAAS 50 Amplifier Schematic for Part 2
Added 2017-03-06 19:43:25 +0000 UTCHere is the schematic we will be talking about in part 2, involving this MAAS 50 amplifier. Those of you that download this schematic now will have a head start in understanding it's function. I'll also explain the function "piece by piece" in part 2 for those of you that may have a difficult time with the schematic. I will also attach this in the video part 2 as well.
See you soon!
This is video #6, include this when requesting attachments.
Patreon NEW LIST of Videos: https://www.patreon.com/posts/8239565
Comments
Good morning all. Likely not a very intelligent question about the circuit for modified Maas 50 amp. There is a 470 uf 450 Volt cap on the 444V rail. Is this one of the can caps on the top of the amp? Is the value critical? I am having problems sourcing such a capacitor at a reasonable price. Anybody have a part number perhaps? Thanks to all.
Jeff George
2025-09-17 13:55:46 +0000 UTCCan’t get the schematic either. No part 2 video too. Thought it was my phone….. Being near sighted it’s the best for watching these without glasses. Just a thought for those out there as blind as me.
Michael in Florida
2025-08-08 01:10:40 +0000 UTCthe video is not there for me either. I guess I'll continue with #7.
Frank King
2025-08-05 20:49:34 +0000 UTCI cannot get the schematic to load.
Mike
2024-05-18 00:04:19 +0000 UTCI am trying to access the Maas50 Part 2 video. Was it removed?
Archie Wharton
2023-10-03 15:53:08 +0000 UTCNo video here.
Chris Bennett
2023-07-11 19:21:57 +0000 UTCHas the Video been removed ?? I do not see it, I can see the Schematic links, but No Video to Part 2.
James Sawle
2023-04-25 23:42:07 +0000 UTCFor some reason I cannot access the schematic. Can you help me out?
RGrabenstein
2023-04-14 04:23:15 +0000 UTCwas there suppose to be a video for this?
Jake M.
2022-11-06 07:47:06 +0000 UTCThank you very much
LoSaYa
2022-10-19 19:56:42 +0000 UTCVery nice tutorial Paul, it really brings up the understanding for how tubes worked and were deisigned back when... these little "secrets" we have when designing and testing cirquits is a wonderful thing to see online.. and it´s my personal opinion that much of these techniques are getting lost as time goes by, like this little amplifier with QQE type tube.... many in the electronic communitys doesent know how much thought process that goes in to it to determine the boundarys of the projects itself, here is where you really shine :-) explaining your thinking behind it all....so again very nice job ...keep it up...73´s / Anders
Anders "SM7HCE"
2020-03-08 09:57:54 +0000 UTCHi Wayne. It's an older program called Traxmaker 2000 Pro.
Mr Carlson's Lab
2019-09-06 19:44:21 +0000 UTCPaul, what software did you use to draw that schematic?
Wayne Thompson
2019-09-06 09:41:55 +0000 UTCHi Bruce. Isolating the heaters to the 6V6 is to stop H/K breakdown. The cathode of the 6V6 is at an elevated voltage as it's acting as a pass element. If the 6V6 was to be on the normal heater line with the rest of the tubes, the heater is close to DC ground. This makes the possibility of a heater to cathode short extremely high. Isolating the heaters of pass tubes is very common.
Mr Carlson's Lab
2019-04-10 11:14:55 +0000 UTCI have only one question about this schematic: why is the 6V6 heater supplied by a separate transformer winding from the other tubes with six-volt heaters? It just doesn't seem to make any sense to me.
Bruce Dow
2019-04-09 19:13:40 +0000 UTCI may consider doing this sometime down the road . Thanks for your input Dan.
Mr Carlson's Lab
2018-08-07 05:52:03 +0000 UTCMr Carlson. I'm a child of the transistor age being 10 in 1980 and grew up learning digital electronics. I have a reasonably well equipped home lab and I have several people that I avidly watch on youtube with my two favourite being yourself and Dave EEVBlog. I find your explanations and detail fascinating and have joined your Parteon group as I have a real yearning to build a wonderful sounding valve amplifier and also because I want to be able to repair and upgrade older equipment. I've looked over the schematic and the first issue I am going to have is the AC mains transformer.... Being from the UK I am using 220V with Live and Neutral rather than a hot live and neutral which is basically an earth. Would it be much trouble for you to show a difference for those of us using the European standard? Would it just be a matter of having 11/6th times as many turns in the primary?
Cowasaki
2018-08-06 23:11:25 +0000 UTCMany thanks. Clarity, reasonable pace, and especially the detailed schematics (with the damn part no.s, thank you again) are what make you by far the best producer/teacher on the web today. God I hope you don't get bored by us yelping seals out here.
Mark Bosse
2017-04-21 02:10:36 +0000 UTCThanks Colin!
Mr Carlson's Lab
2017-03-23 08:31:26 +0000 UTCThanks for your kind comment John!
Mr Carlson's Lab
2017-03-23 08:31:12 +0000 UTCAnother great Video Paul very usefully to me you describe things very well thank you Colin
col
2017-03-22 19:50:02 +0000 UTCI have been watching youtube videos to get me inspired again........boy oh boy there is a lot of dribble out there.....very very frustrating to watch, and I'm glad I found your channel first or I might have walked away again !!...... you do a great balance between talk and hands on......keep things up the way you are for sure......I have now watched every one of your video's and will continue on with whatever you put out next......at my own risk !!
John Harbor
2017-03-19 11:10:57 +0000 UTCah, good! I hate to be such a worry wart. Seems to come along with age, at least for me. Can't wait for the next video!
Stephen Studley
2017-03-17 00:38:16 +0000 UTCHi Stephen, all is good. Thanks for your concern though! I have been working on this next video almost continuously since the release of the last MAAS amp video. Lots of great info coming, and there will be a second "behind the scenes" video as well..... so I'm actually working on 2 video's at once. The new video should be up soon.
Mr Carlson's Lab
2017-03-17 00:07:18 +0000 UTCI hope everything is ok Paul. I sense something unfortunate may have happened to you.
Stephen Studley
2017-03-16 14:27:57 +0000 UTCThats actually most of the work I do. CRT repair in the arcade game industry. It's a dying art forsure and it provides lots of work, and challenging work. Never the same problem and it's always nice bringing these things back to life!
chris lee
2017-03-16 02:26:48 +0000 UTCNice...
chris lee
2017-03-15 16:54:45 +0000 UTCon a more serious note i rebuilt my heathkit lab gen and my leader vtvm while being off from work over 2 weeks!!!
chris lee
2017-03-15 11:51:17 +0000 UTCok...im in total withdrawl!!!!!! need a video soon or a slow suicide will ensue!!!
chris lee
2017-03-15 11:49:20 +0000 UTCThanks John! I'm working on the next video right now, just taking a coffee break :^)
Mr Carlson's Lab
2017-03-12 17:35:05 +0000 UTCThis place is Awesome !! thank you for your effort.....these are without doubt the best Electronic video's I have ever seen......and believe me thats a lot !!
John Harbor
2017-03-12 11:47:19 +0000 UTCI may be wrong, but I think you may have 2 different radios posted. The 2068 shows as transistorized, the chassis #100.202 is a tube console type? This is chassis 100.202 : <a href="http://www.radiomuseum.org/r/sears_roeb_100202_1066.html" rel="nofollow noopener" target="_blank">http://www.radiomuseum.org/r/sears_roeb_100202_1066.html</a>
Mr Carlson's Lab
2017-03-09 20:11:55 +0000 UTCno tubes 12at7,68c5,6v6,6b6
mike Kirby
2017-03-09 19:59:20 +0000 UTCHI Mike, Isn't that radio transistorized?
Mr Carlson's Lab
2017-03-09 19:41:21 +0000 UTCBeautiful, I just started my fist tube receiver thanks to you for helping me understand . Ive googled an can not find schematic. where do I find one for Silvertone # 2068 Chassis # 100.202, Michael WA ST. USA
mike Kirby
2017-03-09 18:32:12 +0000 UTCHi Nathan. It's an old program called: Circuit Maker 2000 Pro. I also use TraxMaker for PCB layouts.
Mr Carlson's Lab
2017-03-09 17:43:57 +0000 UTCWhat a beautiful schematic! What schematic capture program do you use? I'm looking for one that can create some nice schematics like this just for presentation (I use KiCAD for my PCB productions) and your schematic looks amazing. Thanks very much for the amazing content!
Nathan Campos
2017-03-09 13:47:31 +0000 UTCHi Fred. I have purchased all the parts to make a probe for impedance conversion, EG: 1M to 50 Ohm. I just have to get to it (along with many other projects) I will post a video of the probe for all of you to build after I design, build, and test it. If you have a chance to get an HP3585 (A or B) S/A, I highly recommend it. It's a very nice analyzer to work with, and easy to operate. Once I get the chance to upload some of these circuits and layouts, I will make many public for you guys to build.
Mr Carlson's Lab
2017-03-09 09:29:45 +0000 UTCLooks like you will be well prepared. I intend on showing some math short cuts as well, so If you experiment with amp building, these will be very beneficial.
Mr Carlson's Lab
2017-03-08 15:02:15 +0000 UTCI like the idea of printing out this schematic and doing my own breakdown homework before class begins. I've highlighted and label components to there functionally, so when the second part begins I can grade myself and all the question marks will be answered I'm sure. Your were born to teach electronics theory and do a great job with explaining the details.
Scott Acker
2017-03-08 13:37:08 +0000 UTCThe schematic diagram is excellent -- everything labeled and easy to follow. On another note, I am preparing to build your SA Protection Circuit for RF alignment. Would it be possible for you to share with us the full dimensions, parts layout, and foil pattern which you used in the build? I am planning to purchase a Spectrum Analyzer. Unless I purchase the exact model you have, newer models have a 50 ohm input only. I recall you mentioning it would be possible to make changes for use with 50 ohm input. Is this something you could do in a future video? Thanks, Fred
Fred Smead
2017-03-07 21:08:53 +0000 UTCOk reading here: <a href="http://www.aikenamps.com/index.php/what-is-negative-feedback" rel="nofollow noopener" target="_blank">http://www.aikenamps.com/index.php/what-is-negative-feedback</a> If I understand correctly since a loudspeaker does not present the same load at all frequencies, the feedback line "monitors" the output voltage and reduces the gain if the voltage goes higher by increasing the cathode voltage (because the speaker loads the output less at the currently played frequency) . And it also helps correct uneven gain at certain frequencies from the amplifier itself.
Alexandre Côté
2017-03-07 20:53:54 +0000 UTCThanks Steven.
Mr Carlson's Lab
2017-03-07 20:17:03 +0000 UTCHi Alexandre. The 414 does move around with load, it does have negative feedback. Since the Cathode is lifted from ground by a 100 Ohm resistor, if the Cathode is at 22V, the grid will have a bias of -22V. The output would distort, but that's how the owner would know something is wrong with the amp. This would allow him to get it serviced before it completely fails.
Mr Carlson's Lab
2017-03-07 20:11:23 +0000 UTCEnthusiast beginner here: I see some kind of regulation with the 6v6 (I guess for then the 414v drops under heavy load ?), feedback from the secondary of the output transformer (I don't know how that works or why you need feedback). 22v bias ? (22v on cathode, 0v on grid ?). You mentioned that there was some built in redundancy, I can see it with the 5V4G and the 6L6's, but if you lose a 6L6 won't the output be very distorted ? (Much higher amplitude on one side of the sinewave)
Alexandre Côté
2017-03-07 15:55:54 +0000 UTCBeautifully photographed!
Steven Tucker
2017-03-07 09:38:25 +0000 UTChilarious, thx for the laugh. Who says engineers dont have a sense of humor?
Roger Kerr
2017-03-07 04:36:52 +0000 UTCLattice semiconductor is great, (FPGA Thug!) check this out, good for a laugh: <a href="https://youtu.be/gM2hnra55Hs" rel="nofollow noopener" target="_blank">https://youtu.be/gM2hnra55Hs</a>
Mr Carlson's Lab
2017-03-07 03:58:26 +0000 UTCI do admit the Voltages are high, and yes, I have come across much higher. I have some very interesting stories to tell in the future.
Mr Carlson's Lab
2017-03-07 03:56:18 +0000 UTCwhere is the fpga, something i can get my head around, lol
Roger Kerr
2017-03-07 03:55:52 +0000 UTCyes, it was my quirky humor altho i find tubes challenging having never worked with them. The voltages scare the heck out of me.
Roger Kerr
2017-03-07 03:51:08 +0000 UTCGlad you liked the picture!
Mr Carlson's Lab
2017-03-07 03:50:20 +0000 UTCOk Dave, I moved the line over, I do admit it does look better. Keep in mind though, either side of the filament would be just fine, there would be no increase in hum.
Mr Carlson's Lab
2017-03-07 03:38:25 +0000 UTCLOL, your kidding right?
Mr Carlson's Lab
2017-03-07 03:32:23 +0000 UTCcan we start over at "this is a resistor?"
Roger Kerr
2017-03-07 02:49:35 +0000 UTCDoesn't really matter what side, in fact, if you look at the picture, I have some 5R4GY tubes in the unit for normal operation, (lowers the plate Voltage) these have no cathode side designation. Technically, the 5V4 tube is indirectly heated, but configured as directly heated for controlled warm up time. The cathode is connected to one side of the filament. The Voltages were taken (on the schematic) with the original 5V4G tubes in place.
Mr Carlson's Lab
2017-03-07 02:44:39 +0000 UTCGood job on the schematic. Shouldn't the "414V" line connect to the cathode/heater common pin on the 5V4G (Pin 8) rather than the heater only pin (Pin 2)? I'd think the connection as shown would generate a bunch of hum.
Dave07731
2017-03-07 01:54:02 +0000 UTCNice schematic! Added it to my library.:)
Jon Fredrik Våle
2017-03-07 00:07:45 +0000 UTCNIce feddback with 100K Resistor. A classic PushPull
Silvio Pinheiro - PU2SRZ
2017-03-06 22:39:09 +0000 UTCI am not into old anything, but this looks amazing.
Mai Mariarti
2017-03-06 22:23:26 +0000 UTCI think your best "Free" choice is Eagle. <a href="http://www.autodesk.com/products/eagle/free-download" rel="nofollow noopener" target="_blank">http://www.autodesk.com/products/eagle/free-download</a>
Mai Mariarti
2017-03-06 22:19:52 +0000 UTCHi Paul, I'm anxious to see your completed video. The Mass amp is awesome! Tube amps are my favorite. I am personally hoping we will all start building the tube amp you suggested. I would like to request a video one day to include how to measure the distortion and frequency response of a tube type audio amplifier. Also maybe an instructional video on how to use an audio spectrum analyzer with built in tracking generator while we are doing audio stuff.
Douglas Tees
2017-03-06 22:18:43 +0000 UTCHello Mr. Carlson, I apologize if you stated this before, and I think I did see a video of yours where you did so, but what is the diagram editing, creating software you use for your schematics? I am a beginner and was hoping you might suggest a good entry level tool? I realize you are pretty busy and understand if you do not have the time. Kind regards - Steve
Stephen Studley
2017-03-06 21:57:54 +0000 UTCReferring to the after picture of course.
Ron Santos
2017-03-06 21:27:13 +0000 UTCWow! That amp looks amazing!
Ron Santos
2017-03-06 21:26:21 +0000 UTCYou're welcome Carl!
Mr Carlson's Lab
2017-03-06 21:17:46 +0000 UTCSounds good Andre!
Mr Carlson's Lab
2017-03-06 21:17:09 +0000 UTCThanks Mr. Carlson for the schematic. I will try to go through it before you come out with the video and see if I can get the grasp of it to see if I can read it. Thanks again.
Andre Gopee
2017-03-06 21:15:25 +0000 UTCThanks Dawid!
Mr Carlson's Lab
2017-03-06 21:12:00 +0000 UTCThank you for your effort of creating this schematic, maybe the font size of the component values could be a bit smaller but anyway, very clean, easy to read layout!
Dawid
2017-03-06 21:07:44 +0000 UTCAs mentioned above, I think you will really like the next picture!
Mr Carlson's Lab
2017-03-06 21:00:59 +0000 UTCnice desktop wallpaper :) thx
Thomas Peterson
2017-03-06 20:57:39 +0000 UTCHi Denis. The next video will contain the picture of the modified amp, I'm sure you will like that picture for wall paper. Maybe I will attach a long exposure version of that too. There will be more glass on the chassis.
Mr Carlson's Lab
2017-03-06 20:49:37 +0000 UTCPaul, can you make a picture in the dark with long exposure? I need new wallpaper ^_^
Denis Tarasenko
2017-03-06 20:44:50 +0000 UTCThere's some impressive power running through this. Looking forward to the next vid. Thanks Paul.
Carl Loar
2017-03-06 20:28:46 +0000 UTCGlad you like the picture!
Mr Carlson's Lab
2017-03-06 20:10:47 +0000 UTCThe picture of the MAAS amp looks absolutely great. Especially the reflection of your laboratory within the tubes. Thanks Paul!
Reb Elba
2017-03-06 20:07:42 +0000 UTC
