1950 Supro Two-Tube Mini-Amp: Series-Filament Death Trap.....or Safe Little Tone Monster ??
Vložit
- čas přidán 5. 08. 2024
- This video features the heroic restoration of a very rough, but ridiculously cute little 1950 Supro (Valco) "Woodie" amp. Cursed with a broken cabinet, lousy wiring, blown speaker, bad tubes, and the universally-despised series-filament circuit (no power transformer), it had very little going for it.....except its rarity and very small size.
Watch step-by-step as it is restored to good, safe, attractive working condition. Also included (at no extra charge) is a detailed description of the simple, economical method I used to make this transformerless amp as safe as any amp, power transformer or not.
If you enjoy videos featuring classic vintage amplifiers, jukeboxes, and other electronic marvels then please consider subscribing to my channel. You will gain immediate access to 60 more (hopefully) entertaining videos and you will be notified each time a new video is released.
Also, for those who would like to build a copy of this circuit, here is a detailed schematic created by a viewer: photos.google.com/share/AF1Qi...
Thanks for watching !!! - Hudba
Thanks, 2005. I taught Math and Science for 16 years, and became acutely aware of the necessity to explain things in a clear, understandable way if you really want to convey knowledge. Talking down to an audience, or over their heads is a complete waste of time for all involved. I really appreciate your comment and your subscription to my channel.
Greetings, F86. My electronics knowledge was self-taught over the past 35 years or so, working on radios and jukeboxes initially and more recently on amplifiers. I was a middle school math and science teacher for 15 years, so I guess the flair for teaching developed then. Thanks so much for your kind words. I sincerely hope you enjoy the rest of my videos.
Another great video from you. This repair was a total labor of love. One can really tell you care about preservation of guitar history. This little Supro was lucky to have ended up in your hands.
Thanks, Brad. It's obvious that you're a Supro fan :) I had never seen a vintage guitar amp this small (or cute), so I couldn't resist "going the extra mile" to restore it. As a bonus, it ended up sounding a whole lot better than I expected. Also, when I sell it, I can ask a real high price......because it's the same brand as the amp that Jimmy Page once used :))))
Jimmy would be proud to own it himself I am sure!! It sounds amazing!!
@@UncleDoug lol. I just find it hard too believe you are that type of person.
You're welcome, Ron. I am flattered that you would take the time to watch all the videos, and I really hope you enjoy them. Best of luck with your own amp project.
I love little amps like this, especially old ones. Maybe because I’m little, and old 😂. Thank you so much Uncle Doug. I’m re-viewing all your videos for, I don’t know, the tenth time. I have to review everything you’ve taught me just before I return to my basement workshop every fall for my winter hobby of tinkering with amps.
Greetings, Jimbo. We're glad the videos are helpful. Good luck with your projects :)
Uncle Doug, you are the most informative person on the internet for tube amp knowledge. The other thing is your dry humor just cracks me up all the time, and I know I have told you that before, but you make me laugh a lot.
The annotations on this video gave me more chuckles than usual.
+kcrmson Glad you liked them, Cory. Sometimes I'm in a really good mood when making a video, and I guess it shows.
I love these restoration projects,the before and after pictures are amazing,this is really good work.
Thanks, Colin :)
Thanks Uncle Doug, I always learn something from your videos.
That's good to hear, Peter :) You're welcome.
The amount of charm this little amp has is unbelievable. Someday I'll find one for myself!
Thanks so much, Alexandre, and best of luck in your quest :)
always amazing to hear what a few new capacitors can do with the sound of an old amp
Agreed, Remi.
Just gotta say those hand drawn schematics are really well done ! Thanks for the informative video
Thanks, Brandon :)
WOW.Fabulous little amp, great tone, and a top notch restoration. Very cool.
Thanks, JM :)
The thing is, my knowledge of electronics is on a reasonably comfortable junior or novice scale but I am certain that I am picking up all kinds of knowledge slowly just by osmosis, as Uncle Doug’s humorous narration and confidant knowledge make these the most entertaining guitar amp tech videos I’ve ever seen.
That's great to hear, RR. Thanks so much :)
Thanks for another great video and I love your dry sense of humor especially when describing an amp in the first look at it, and what others have done to it, or its general condition . Good luck at Wimbly stadium.
You're welcome, Z. Sometimes humor is the only way to keep from getting angry or cynical over the harm that careless, unqualified "techs" can cause :)
21:28 'I don't think it's gonna put Fender out of business.' O the sweet irony seeing as they bought Gretsch. That is a great little amp, and you definitely gave it a new lease on life it deserved. Thanks Again Uncle Doug. Been learning a lot watching your vids.
You're welcome, Paul. Actually I notice that Supro is undergoing a strong rebirth, with all sorts of newly-designed, excellent amplifiers on the market. I wish them great success.
@@UncleDoug I have mixed emotions about new and revamped Supro. I've been hearing things about the new Jimmy Page Supro they reissused, and they've got none of the old Valco ptp wiring, or feel to them apparently. I think it's the folks at Pigtronix that revamped them, which is fine. Again, good to see them come back in what ever form, but wish they would have kept the old Valco standards. But anyway, you keep fixing em, I'll keep watching. :)
very cool build, thank you for sharing , awesome little amp and amazing work youve done. Thank you
You're quite welcome, Bryan. Rusty and I really appreciate your kind words and the time you take to watch our videos :) ^. .^
Uncle Doug. You have awesome videos. TY! This is very interesting.
Thanks, Marc.
excellent excellent video, a 10 out of 10.
Love the way how you explain to make the chassis safe.
I had the same concern about the tubes being too close to the speaker magnet, but you did a really fantastic job on refurbing that.
AssAlarmMyLincoln Thanks so much, AA. Glad you liked the video :)
I flinched when you turned it on, great acting! Funny as all heck....
Thanks so much, Rob. My acting coach will be glad to hear this :)
Very nice. Just today I was searching the web for schematics of an amp with no PT. Should have known you would have one. At the risk of sounding like a broken record, thank you so much for the time and effort you put into these videos. I have attended much training in motor control electronics (forklifts) and have never experienced a better instructor. Now that I no longer work I needed some kind of gearhead hobby and vintage amps seem to fit the bill.
You're quite welcome, Bobby. You'll be glad you chose vintage amps as your retirement hobby.....it's both challenging and rewarding :)
Great video! Thanks for posting that, and thanks for going thru all that trouble.
You're welcome, Paulo....glad you liked it :)
Once again Uncle Doug to the rescue, I Recently picked up a decent amount of old wooden radios, hoping to turn a few into small desktop amps, And sure enough, I have a little CL-543 which has that complement of tubes and a 50z5 rectifier and a handful of 120vac to 120vac transformers. Doug you and your channel are a fountain of knowledge.
Thanks, Pat. Good luck with your projects.
Beautiful restoration/preservation of that nice little amp. Thank you.
You're welcome, Terry. Glad you enjoyed it :)
:-)
Nice restoration. It's much better than when you started.
Thanks, HB. I thought it turned out real nice, especially considering how awful it was to begin with.
Oh, I love these old Valco amps. I had a Supro tweed. One day I hooked up a distortion pedal to it , WOW !
Valco amps are among my favorites, too.....well made, sound great, and generally affordable.
Great job. This amp has a great look to it. Loved this video.
Thanks, Dave.
This is really nice, thank you for the schematic.
You're welcome, TT.
Thanks, BT. I too was impressed by how good it sounded.....especially considering the limitations of two tubes and a 5" speaker. I'm glad you liked it.
Thanks, Frank. I was with David when he took the SVT apart and I couldn't believe how hard it was to disassemble.....what a repair-man's nightmare !! It reminded me of old cars that were so poorly designed you had to pull the engine to change a spark plug. This is why I stick with simple vintage amps.....so much more fun to work on.
As always another great video, every one of them is a learning experience, thanks
Excellent video! Many thanks!
You're welcome, IY :)
thanks Doug, great video must finish off my own design valve amp and put it on my channel. I am watching your vids in revers order, which is fun.
More fun!
I have an almost identical Natco projector suitcase cab like yours.
Another Bell & Howell as well.
I know that some are made of metal. Nice long leads in projector cabs too.
All coiled up neat with a reel and soft red material, lol.
Good to see these videos!
Glad you enjoy the videos, Amo.
Thanks, Bill. I'm glad you enjoyed it.
Great tip with the screen wire behind the speaker cloth - I can put this to use!
davida1hiwaaynet Glad you liked the idea. The screen really helps to support and flatten the grill cloth.
Uncle Doug, you rock. I like your voice and your pacing, the subject matter, everything. Thanks for your hard work. Subscribed!
+wrathVchild You're welcome, WC. Rusty and I really appreciate your positive review of our work and welcome you to our channel.
Thanks for posting this site. The Supro student lap steel guitar they have for sale is probably just what this little amp was made for.....the wood color is similar and the Supro ID tag is identical. Very interesting.
Great video thanks. The amp sounds pretty good.
You're welcome. For it's size, I think it does too.
Great restoration job.
Glad you like it, Franko.
Awesome job
Thanks, Tim.
Good job !! Sounds nice !!
Thanks, Kal. I'm glad you enjoyed it.
uncy doug, it's a pleasure to watch rhese vids-keep em comin!
i LOVE this little amp. love the simplicity. im also beginning to love the tone of a pentode preamp. i want to make one of these and put it inside a 30s tombstone radio cabinet w/a 6". i think that would be appropriate since so much of this design comes from tube radios, especially the power scheme. if i want more drive, put a boost pedal in front of it.
I'm glad you like it, Jim. Good luck with your project. I think you'll find that any sort of boost pedal will seriously overwhelm the 6" speaker.
Cute little amp. I like it!
Thanks, Sean.
Very cool little amp.
Thanks, Bryan.
Sweet ! I'm starting to get inspired...
That's good, Bill. There's work to be done !! :)
thank you for this exceLLent & informative safety 1st video .
I'm amazed you left that selenium rectifier in there! Those things can give you a puff of nasty poisonous smoke when they fail.
I don't recall leaving it in, Frank. Generally I remove them, primarily for reliability.
Very awesome video sir!
***** Thanks so much, Stephen. Glad you liked it :)
This one is by far my favorite video from Uncle Doug. The utter simplicity of this amp is simply amazing and yet it produces great tone with even the tiniest of speakers. The Stewart amp could not achieve that even with three times the cone area.
Wow, thanks so much, Mark. I got it from a friend. I was at a party at his house and complimented it.....so he gave it to me :)
@@UncleDoug nice gift
@@gerardcousineau3478 Yes, it was.
@@UncleDoug hi Uncle Doug, I have a question this guy did put a three prong plug on an amp very similar to my Lifco model 801 could you give a look and let me know if it's the way to do it. woodeso's guitar mods is the site. You can maybe bring light not just to me but others who are wondering about this mode. It'll be generous of you to give it a look and maybe leave a comment. Be certain it'll be very appreciated. Finally I'm glad you're doing well.
@@gerardcousineau3478 Gerard, I have demonstrated repeatedly in many videos exactly how the 3-wire cord should be installed. Rather than simply repeating myself, please watch one of these videos and see if your cord is installed in the way I demonstrate.
I will, Padraic, and I really appreciate your kind words of encouragement.
You're welcome, Mr. Fitz. I'm glad you liked it.
you done a Wonderful Job ;-) ..and can tell the Amp feels better looks better and Sounds Better, Your truly an " amp doc " !! ..Love the "Natco" Vintage speaker at 20:58
I have a smaller one with a Jensen 10" with the leather corners..
This amp knew where to go and so glade you fixed her up, you did a Great Job :)
Thanks so much, B2. It's nice to know that someone else understands the pleasure derived from restoring something that has been abused and damaged back into its former, good condition. I really appreciate your input :)
Hi,long time sub,1st comment.Love your work and just had to say what a fabulous job.Beautiful restoration and long needed safety work on a potentially dangerous build and it does sound fantastic.Thank you Uncle Doug.
You're welcome, John. Thank you for subscribing and for posting such a nice comment. We sincerely appreciate it :)
That little thing sounds great and you have yourself an 850 to $900 amplifier the collectors going to see that and the rest is history.
Thanks, Mark. I hope you're right :)
Sounds amazing, even in the 5" ...in fact, that's where IMHO its charm is.
Just wanna say, your restorative ethic has my vote all the way home. In fact I can't imagine any other POV. I'd like to hear some single high-ish guitar notes with the volume nearly maxed as in 'lead lines'... I bet it would sound really cool, daddy-o (as this thing is old enough to've been plucked by beatniks). thanks for another great video and...
cheers
You're welcome, Jonny. I too was pleasantly surprised by the sound quality of the little guy. Thanks for your nice comments :)
That little amp is totally awesome. :-)
Thanks, Terry :)
You're welcome :-)
Very nice!!!
Thanks!!
For some reason this wild but kinda classy little amp really speaks to me. It did look like a rats nest but Doug nailed that restoration. I looked for other demos of the amp after seeing this and none came up, but man it sounds good as is.
Thanks so much, Davo. The little guy is so small you could almost hang it around your neck with a chain....rapper style :) Rusty and I are glad you liked it ^. .^
Nice job Uncle Doug.
Thanks, Dave :)
That thing must Rock Out!
Yes, indeed, CH :)
And Uncle Doug does it again! Another great video :) This amp was a trip to see! Interesting series circuit. I've never seen an internal isolation transformer on an amp yet. This is a nice little practice amp; a lot better than the crap sold these days...It's funny, I watched David's latest video on the Ampeg SVT and I was cursed with one yesterday morning...Same issue as his...My girlfriend said, yesterday was the first time she heard me swear while working on an amp (LOL) I enjoyed this video.
Uncle Doug you got to be the best I have ever seen!!!! absolute world's best ,,,,that thing looks like the Lord performed a miracle on it. My God.
Thanks, Mark :)
A cute little amp. A lot of work went into the radio-like cabinet originally. Designed to look at home in the home. What was it designed for? Leo was just taking his 1st steps towards turning the music industry upside down and inside out, so it wasn't for him. The existing jazz boxes with added pickup didn't need an amp for home noodling... Impedence matched for a magnetic transducer, though. Thank you, Doug, on behalf of guitar nerds everywhere.
Thanks, Bill. My guess is it was for lap steel guitar.
love your humour UD
Thanks, IM.
12SK7 is a remote cutoff pentode commonly used for RF and IF amplifier in radio receivers. It was designed to work with the AVC circuit. The 12SJ7 is a sharp cutoff pentode which is much better for audio gain service.
Thanks for the info, Daniel.
This is so much better than the cheesy china made practice Amps sold today, and classy looking and warm sounding too. Would even make a great harp amp.
+David Salny Thanks for your kind words toward the tiny Supro amp, David. I agree completely. As small and simple as it is, I would definitely prefer it to virtually all of the small, modern amps currently sold.
How did I miss this episode? I have to admit that I had no hope for this economy -class Supro. However, my doubts were dashed by your understanding of circuit design. You made a potentially dangerous design in to a safer, logically sound amplifier. The restore of the cracked wood was well done; considering how poorly protected the original finish aged. This adventure was well executed, dear uncle. I need to traverse your entire catalogue of videos for any other I may have missed. Stay safe!
Thanks so much, Alex. Glad you enjoyed our efforts to restore the little Supro. We hope you enjoy the rest of our videos at least as much.
Hi Uncle Doug & Rusty, I have a 1945/6 Crosley 'American Overseas' model 56TC, wood cabinet radio that has some similar tubes as the Supro. It has the 50L6GT beam power tube, a half wave rectifier the 35Z5GT and a 12SQ, SK, and SA7 tube compliment. The 12SA7GT is a pentagrid converter, I'll have to research that. Still collecting parts for the 5F1 Champ, I have a new Jensen MOD series 8"-20 watt, 8 ohm speaker, and some jacks, pots, etc. for the build, can't wait to start it. I hope doing good, Take care, C.
+Cass Virgillo Cass, it sounds like the Crosley is a series-filament circuit (no power transformer) and therefore not a great candidate for parts donor or conversion to guitar amp. Good luck with your 5F1 Champ project.
Thank you Uncle Doug for all the time and effort you spend putting your content-rich videos together.
I am trying my hand repairing a mid-60's series filament amplifier. What are the advantages and disadvantages to using in an isolation transformer for the mains inputs rather than the simpler approach you've taken?
What was your decision process not to use a transformer for this Supro?
What input did Rusty and Jack have for the design choices?
You're welcome, Kevin. I personally have never used an isolation transformer on any amp, series filament or not. To me, grounding the chassis seem like a foolproof way to eliminate the shock hazard, and it allows the amp to remain original looking, without the need for any additional bulky electronic components.
Thank you for the feedback Uncle Doug. It does make sense that a solid ground to earth would be sufficient. Best regards to Rusty and Jack.
By offering the ultimate, virtually zero-resistance, path to earth ground, it only makes sense that the pesky electrons, lazy opportunists that they are, would follow that path rather than the relatively high-resistance path offered by our body, especially if we are not grounded. Granted, since we would form a voltage divider (us and ground), there might be a slight sensation of electrical flow, but it would serve more as a warning than a threat to our health.
also i like the sound of an amp with natural overdrive as opposed to a pedal
😀😊💀ttZZzzzzztt💥⚡brilliant ! thats a great little amp uncle doug,
and not too dissimilar looking to my ancient BUSH valve radio ,,
Thanks, William. Glad you enjoyed it :)
Nice Uncle Doug.
Thanks, Chris :)
a shame back in the 60's / 70's some artists used to slice the cone to get that ratty, flabby nasty grit out of these little monsters. (the kinks / you really got me)
as always, great video Doug.
chuck jones Thanks so much, Chuck. Yes, I've heard tales of some very famous musicians (including Keith Richards, I believe) who cut and otherwise damaged speaker cones to get that ragged tone. Thanks for your input :)
+Uncle Doug They got the idea from some of the old black blues players who sliced their speaker cones with razor blades back in the '50's.
Sort of an irreversible modification.....but I guess they really wanted a raunchy sound.
Reminds me of the "All American Five" AC/DC AM radios.
Lots of small, inexpensive amps used the power-transformerless circuit.
This is the ultimate night stand amp! I’d rather have this to play myself to sleep while writing the next “Satisfaction” than any modeling amp! Just don’t spill your beer 🍺⚡️
Glad you like it, William.
Wow! A Selenium diode, that's old, old school, as far as diodes go.
Yes, and probably containing deadly chemicals....but my rule of thumb is, if it works......leave it in the circuit :)
As you're probably aware, in the UK and Europe, we got 230 volt mains. This amp, if built for Euro mains, would be even more lethal.
Greetings, HB. This amp would not be hazardous, as I explain in the video, but I would be very nervous about contact with a different untested, series-filament chassis. As a rule, I don't buy or work on them. Thanks for your input :)
I actually tried it, Ben, and the increase in volume and distortion wasn't a whole lot greater than at 7 or 8. I think the preamp tube was saturated and couldn't drive any harder. The response to input is definitely non-linear at higher volume settings.
Lov your work! Awesome.
I would like to see you take on a big tube amp. With say 6 or 8 out put tubes that has issues.
Like a dyno test of a genus.
Thanks!
See some of my more recent videos, Curtis, featuring 50 to 100+ watt monsters.
@@UncleDoug nice. But how about a ps 400 fender. ?
@@curtismuma1931 I don't see that happening, Curtis. I doubt that anyone would want to pay the shipping cost for the head and three speaker cabinets.....and I would definitely not want to have to lug them back to FedEx when the video was done :)
@@UncleDoug i agree too heavy to ship. Just a pipe dream. 435 watts of tube power wow. Alot of people have never heard of this amp. There is one for sale in my sound room.
m.facebook.com/groups/537776489920188?view=info&refid=18&ref=bookmarks
a nice brige rectifier would boost plate volts and couple of good caps. 12volt heater transformer ? great vids doug luv them
freak55beat Greetings, FB, and thanks for the kind words. I agree that a FWBR would be an improvement over the Selenium Rectifier, but I tend to not alter vintage amp circuits, especially when the existing parts are fully functional. This is a series-filament circuit, so the heaters (and 300 Ohm 10W Resistor) take their appropriate operating voltage from the 120VAC wall receptacle supply, with the sum of their voltage drops equal to the input voltage. There are no power or filament transformers.
There should be a concept amp called Flapping In The Breeeze, where all components must be able to catch wind while in use.
That's a wonderful idea, OM. It should have a built-in fan to ensure proper flapping at all times :)
Hi Uncle Doug! Great informational video and I love those tube amps too! But I don't see why you say this little amp is a death trap. You had mentioned that it does not use a power transformer, but it does indeed : for the B+, and thus the B- can be connected directly to ground and still be isolated from the power line. Connecting the tube heaters in series is not dangerous; and the schematic shows no direct connection between the power line and ground. BTW I used to work on Marshall amps many years ago and remember fuses wrapped with foil and smoked transformers ;-)
Greetings, WG, and thanks. I agree with everything you said, and tried to make these exact points in the video. If I failed, then I apologize. The title had two parts, the first part (about "deathtrap") was intended to be ironic, and the second part (about "safe little tone monster") was, in my opinion at least, reality.
Re the "modification" of fuses, my favorite is the tale, probably apocryphal, about the guy who substituted a .22 caliber bullet for a fuse in his car.....which led to all sorts of unpleasant surprises. Let's hope no one follows suit in their amp :)) Thanks for your input.
I'm always commenting too soon, as I do this and consider it important and pause the video, and typically as soon as I do, you'll say the same thing... but here goes! My house is quite old... but I find this in a disturbing number of places that I play, that the ground on the outlet is often not earthed... but floating around somewhere... early on in my gigging career, I found many places that I played, playing HECK with my amps and always carried a little outlet checker with me.... and for whatever reason, those grounds were nearly always OPEN... causing ground loops and mass carnage!! And one place that I enjoyed playing immensely had HALF the stage wired with the hot wire and neutral, BACKWARDS... CAUSING me to receive a full-on jolt of 120v to my lip! And another time, before they took my advice and had it wired to code, I was preparing to play my first song of the evening, talking to band members, and having lost a high E string at our previous gig, had about 6 inches of E string sticking out... as I talked to the guys before the song I thought someone took a picture of us with a flashbulb, but everyone's eyes got wide... and the distinct smell of ozone drifted into my nose... and the 6 inches of E string was now 3 inches after touching my vocal mic... that was the night I talked with management. And the next day bought a cheap little outlet checker... I have an old mic stand tube at the house, driven about 3 foot into the ground, and hard-wired to all of the audio circuits in the house, and all of the outlets with active grounds labeled as such... just a little PSA from the guy who probably has been shocked more than any of your other viewers, I'll wager! Lol.
Wow.....thanks for sharing these cautionary stories with us, Sean. Hopefully, viewers will heed your warnings.
what a speaker stash that yielded that LIttle Gem (for never was the term more warranted!) Actually looks like it came from near Wembley... or the UK,. generally.
Yes, it was secretly removed from George Harrison's speaker cab during an intermission, smuggled out of the country in a fruitcake tin and sold to me at a flea market in Juarez, Mex.
@@UncleDoug OK when the millenials laugh this much, they type the letters RTOFL - but no word of a lie, Doug, I don't know what it stands for.
PS incredible! we're now down to a 2-tube amp - which i guess you could carry from practice to gig, to be sat atop a singe 12 cabinet or similar,,already lugged to the venue
@@andrewgillis8572 Indeed, it could power my 3 x 15" Kustom speaker cabinet quite well.
@@UncleDoug The 3x15 Kustom - with naugahyde - put that in your show rider, knowing the promoter won't find one - the Chuck Berry technique. Used here in Halifax Sept '74 when no one could find two Fender Dual Showman Reverbs & cabinets.
I believe in torts this is called, a ding-a-ling..
Chuck picked up an extra $750 - for a while it looked like the promoter couldn't find that, either.
I use contact cement made by Dap..from home depot to repair the speaker...it works the best for me...
I use contact cement for the same purpose, Kenny. Please see my video on speaker repair.
Americans really need to get their power plugs together. In Australia, even with a two wire plug, you still can't plug the thing in backwards. Also the plugs don't lose their grip on the socket!
I can be a pretty old school person when it comes to electronics, despite my age. That said, this amplifier even made me a little uncomfortable right from the start with the lack of safety. Good job at whipping it into shape! Sounds nice.
Thanks for your input and nice comments, Liz.
NICE..
Thanks, JJ :)
The 12SJ7 is a sharp cut off pentode. The SK is a remote cut off used for RF/IF amplifier service to accommodate AVC. The Selenium rectfier should be replaced by a silicon diode.
Thanks for your input, Daniel.
The flow of electrons into the tube can be disturbed by the proximity of a magnet strong enough, this can cause red plating. That's why the speakers in cathode-ray tube TV are shielded.
Thanks for your helpful input, Andre.
the 5-inch speaker is basically an open back mid-range, similar speakers were used in numerous Magnavox and Motorola Hi-Fi consoles back in the 1950s. if I remember correctly, alnico five actually refers to the way the magnet metals are alloyed, the ratio of one to the other, or the number of medals in the alloy, or something like that. some alnico magnet formulations, in addition to Aluminum, Nickel and Cobalt, also had some copper, but I don't remember what the fifth metal could be.
Thanks for the informative input, GU :)
Doug ~ :) ~ at the risk of 'telling you what to do'....let me recommend getting yourself an old lap steel for the express purpose of demonstrating these 'little' amps. I think that's what they were designed for, or at least marketed for....specially back in 1949 - regards!
Carl Rudd I think you're right about the original purpose of these small amps, Carl. I did have a really nice 1940 Rickenbacher lap steel a couple years ago, and am ashamed to say that I wasn't sure how to tune or play it.....but it did sound really nice through an amp. It reminded me of Hawaiian music, and inspired Rusty to practice his hula :)
nice work ok just wondering about antiques
Thanks, James.
Hey Uncle Doug & Rusty, Very nice restoration. A while back I learned about a new company Lone Wolf, who make a Harp amp called the train 10, they have others too. It is part tube, part solid state and only costs around $350.00. I was wondering what you thought of a hybrid ( for lack of a better word ) amp like that. Not true tube, but, with the solid state it could perhaps last quite a while, if quality solid state components were used. I am planning to get a schematic of a Fender 5F1, study it, and, as funds become available, start to purchase the parts to build one. I was a machinist for over 30 years, so, will scratch build like you do. Thankyou for all the great inspiration. Take care, be good, C.
+Cass Virgillo Thanks, Cass....glad you liked it. I'm not a huge fan of hybrid circuits, but it's simply a personal bias (no pun intended) toward pure tube circuits. Hybridization is useful to reduce building cost and to offer modeling and complex effects, like chorus, octave, flange, etc. and to reduce overall size and weight. I'm just an old fashioned fan of pure tube circuitry with tremolo and reverb (if possible).
The 12SK7 is very similar to the 12SJ7, the difference being in the cutoff characteristic. You might want to see how the two compare in the circuit.
Excellent suggestion, D20. Thanks !!!
btw oldest amp ive ever seen with diode rectifier. mind blown.... not even a 6x4? even my cheapo kmart tube amps from the 60s have 6x4s...cool!!!!
this amp, les paul. one sm57. a fuzz. # 1 guitar rig ever
A real minimalistic amp
That's nice to hear that you were a school teacher you're very thorough to the point and easy to understand I really appreciate your program
Thanks so much, Bruce :)