Rare & Wonderful: 1946 Gibson BR-1 Amp and 1941 Triplett Tube Mini-Tester

In this two-part video, we will first explore a really nice, original 1946 Gibson BR-1 amplifier. It was Gibson's most expensive post-war amp ($190), and sports both DE 6L6's and a big, heavy 12" electrodynamic speaker. It is not only beautifully built but also offers a real surprise regarding its operational voltages. Ultimately, the amp is repaired and thoroughly audio tested by Jack & Ollie :)
In the second part of this video, we will evaluate, repair, and test a miniature 1941 Triplett tube tester in mint condition, comparing its tube measurements with those obtained from a Hickok 600-A tester.
If you enjoy advertising-free videos such as this one, then please subscribe to our channel and consider becoming a Patreon patron at: / uncledougsvintageamps or making a PayPal donation to: [e-mail]. If you prefer, vintage equipment and components may also be donated for use in future videos. Thanks for watching !!!

[@UncleDoug]

In retrospect, and as noted by several astute viewers, the 20K resistor to ground is not responsible for the low B+ seen in this circuit. It may serve to drain the electrolytics when the circuit it turned off, but its parallel (rather than series) positioning would not cause the B+ reduction. Apparently, the HV winding of the PT was configured to create a lower-voltage higher-current output, which was further reduced by the addition of the huge filter choke (probably added to the circuit at a later time).

[@tomfrye9037]

If it were me, I'd bypass that second choke and see if hum occurs. If not, one could probably do without it. I remember back in high school when a friend was getting ready to add more inductive filtering. He was getting more hum that he was willing to endure. I told him to reverse the audio feed wires to the voice coil first. That hum bucker coil under the spider only works if the polarity is right. That did save him buying and adding another choke.

[@UncleDoug]

Thanks, Tom. The amp is long gone......back home with its owner.

[@tomfrye9037]

@@UncleDoug And probably been used a time or two(8-). I didn't stick my head inside the speakers here, but I didn't hear the least hint of hum out of that old Gibson... So that extra choke certainly didn't hurt anything.

[@UncleDoug]

It was quiet as a church mouse, Tom, which is always a good thing :)

[@dirkbonesteel]

More important, don't think there was such thing as a really good used car in 1946

[@dwp1970]

Jack and Ollie playing some "James Gang" made my day, not to mention that beautiful wire management in the BR-1. What a treat!

[@UncleDoug]

So glad you enjoyed it, DWP. Thanks !!!

[@daveogarf]

MAN! Sounds like Jack & Ollie have been practicing! They're gettin' GOOD!

[@UncleDoug]

Thanks, Dave.....I'll tell them :)

[@OIE82]

That was amazing to see. That Gibson sounds great. For 70+yo. The tube tester was in perfect physical condition. I am old enough to remember seeing those (dust covered) at the corner drug store but didn't know how to use them. Thanks for the tour Uncle Doug.

[@UncleDoug]

You're welcome, Luther. Thanks for joining us.

[@erikjohansson1814]

Nothing like waking up with a proper hangover and find that Uncle has uploaded yet another fantastic video 👍🏻 Sure beats Aspirin anytime.

[@UncleDoug]

High praise indeed, Erik. We'll be uploading another video soon, so prepare for some more boozing :)

[@samuellord8576]

Erik et al, as much as I resemble your remarks, for ancillary relief drink plenty of orange juice _before_ collapsing. Most hangover woes flow from an acute potassium deficit, so large, preventive doses of bananas and/or OJ, _and_ water, will brighten your Uncle Doug mornings all the more. Word.

[@milanlazic6640]

Every new video from Uncle Doug is a little celebration for me .

[@UncleDoug]

Thanks, Milan :)

[@ix-Xafra]

Thanks for the additional feature Uncle Doug. Loved the Gibson amp story too

[@UncleDoug]

You're welcome, Vinny.

[@Tonetwisters]

This amp is about as old as I am ... Great work! Amp sounds fabulous!!

[@UncleDoug]

Thanks, TT :)

[@domperroud4014]

Glad to hear Jack has no more problems creating a few good tunes...his paws appear to be well.

[@UncleDoug]

No, he is back in good playing form. Thanks :)

[@imannonymous7707]

Isnt it grand ! When you got something that would last the test of time. And it still looks exquisite too. Thank you doug for all you do

[@UncleDoug]

You're welcome, IA. I agree, it's a nice combination.

[@pethoviejo]

Love that art deco lettering on the amp control panel.

[@UncleDoug]

The graphics are all part of why I really like these very old amps.

[@Finom1]

Our family loves hearing you play!! Thank you Uncle Doug!

[@UncleDoug]

You're welcome, F1.....from Ollie & Jack :)

[@Finom1]

Your are all part of our family!!!

[@UncleDoug]

Wow.....thanks so much, F1 :)

[@bluesbondsman]

Sounds like the 1950's sound to me ! What a cool amp.

[@strangequark420]

This thing sounds GREAT! Way to go on the restoration, sir ... just beautiful.

[@UncleDoug]

Thanks so much, Tim :)

[@dansmusic5749]

I just love your sense of humor Uncle Doug. It is always a delight to watch even the most mundane of your videos. You've got a great voice and wonderful delivery. Great channel. Excellent content and info. Keep 'em coming.

[@UncleDoug]

Wow, thanks so much for all your very nice comments, Dan :)

[@matthewenderby]

Glad to see another video @Uncle Doug

[@UncleDoug]

Thanks, Matt :)

[@PeterDad60]

That Gibson amp sure sounds good to my ears! I seem to enjoy your video's, more than any others that I can bring to mind. I am always a student and you are always a teacher. Heck, I'm 69 and I love to learn. Your calm, and in depth discussion as you go through the amplifier's are so conductive to learning. I thank you for who you are and that I am able to view your educational video's. -Peter

[@UncleDoug]

Thanks so much for your very nice comments, Peter. We really appreciate them.

[@Finom1]

Bless you Uncle Doug for sharing your wisdom with us!!! Your just the best!

[@UncleDoug]

Thanks so much, F1 :)

[@nikmilosevic1696]

What a fantastic old amp, good to see it up and running again.

[@UncleDoug]

Thanks, Nik :)

[@Wade6242]

Beautiful work as always Doug. Peace

[@UncleDoug]

Thanks, Wade. Likewise :)

[@olipito]

Love the amp, but especially the vintage gear repair and test! Mooore! 😍😍😍

[@UncleDoug]

Thanks, O. More is on the way :)

[@MauricioRamosdaSilva]

Thanks for share your knowledge. Great lesson as always!

[@UncleDoug]

You're welcome, Mauricio.

[@fullwaverecked]

What a stunning piece of history. A top notch presentation. Thanks Uncle Doug!

[@UncleDoug]

You're welcome, FW. Thanks !!

[@randolphcordell6380]

Wow NRI. Nostalgia! I obtained my computer training through their Master Course In Microcomputers and Microprocessors in 1986. It took 3 years of correspondence training at home to complete. Most people have never heard of National Radio Institute. Sadly they are gone now. Wonderful video, both parts.

[@UncleDoug]

Thanks so much, Randolph.

[@rcjward]

What a great sounding vintage amp! Thanks for the look inside, Doug. Great stuff as always!

[@UncleDoug]

You're welcome, Ronny. Thanks !!!

[@richardweinberger2756]

Beautiful construction of that tube tester. Love that amp too !

[@UncleDoug]

Thanks twice, Richard :)

[@griffithlewis1325]

What a great sounding amp! And an NRI tester to boot, I still have my NRI test equipment from when I did a cert in comm electronics when I was a kid.

[@UncleDoug]

Thanks, Griffith. We're glad you enjoyed it :)

[@rohankhemraj]

Great video. I especially enjoyed the tidy wiring on that old gibson. Also, nice job cleaning up the control panel.

[@UncleDoug]

Thanks thrice, Rohan :)

[@bobsbarnworkshop]

I may have commented on this before but my dad bought that model amp and a Gibson lap steel guitar before I was born! He gave it to me to use when I started playing guitar and singing when I was about 12 (1964ish!) it didn’t work when he dug it out of the attic, so it went to the local electronic genius much like yourself! I practiced and played through it until I bought a used 68 bandmaster about 1970 with the tall speaker cabinet with JBL speakers. That amp was destroyed in the flood of 72 in NYS.

[@UncleDoug]

What a shame that it was destroyed, Bob. Either amp would have been a nice heirloom.

[@bobsbarnworkshop]

Uncle Doug the BR-1 was LOUD too! Now that I think back, I blew the original speaker and just put in a replacement from Lafayette at the time, wrong type because as you know better than I, the original had extra coils so it never sounded right after that. Must be the reason I bought the Fender. I gave the Gibson to a friend and that was flooded too! Love watching you bring vintage amps back to life!

[@Bigjoedo66]

Great Video Uncle Doug!! I have never seen an amp biased with such a low plate voltage

[@UncleDoug]

Thanks, Big Joe. Neither have I.

[@kauwgomboom]

Aside from the usual awesome restoration, I am really astounded by the great sound! What a great overdrive and so dynamic!

[@UncleDoug]

Thanks, GH. Glad you liked it :)

[@MegaTubescreamer]

awesome uncle doug,really enjoyed the work and problem solving capabilities in this and in most all of the posts i`ve seen so far, and i know there are lots of em to look forward to, thankyou ,

[@UncleDoug]

Glad you enjoyed it, William.

[@tmitz73]

Awesome Vid Uncle D!!!!!

[@UncleDoug]

Thanks, T73.

[@ianbutler1983]

Thanks. I enjoy all of your videos.

[@UncleDoug]

You're welcome, Ian. We appreciate your time and interest.

[@boctok55]

Making Mondays easier to deal with. Thanks for another great video!

[@UncleDoug]

You're welcome, B55 :)

[@marklowe7431]

This amp makes all other 'rare' items seem not so rare. Amazing.

[@UncleDoug]

Thanks, Mark :)

[@49VinCom]

The Gibson sounds great, love the tube tester. Thanks.

[@UncleDoug]

Thanks, 49....glad you enjoyed it :)

[@garybevis8691]

Sometimes it seems like they were designed by someone that did not want anyone to service the chassis. Great work as always Uncle Doug.

[@UncleDoug]

That's true, Gary, especially with all the components hidden under the immovable terminal board. Thanks !!!

[@steelfistIII]

Great work on the Gibson, Thanks Big Dave for the contributions! The wiring in the BR1 was something to look at. I noticed the same kind of wiring work in the tube tester. The amp sounded surprisingly good, i didn't expect that one. Fantastic video Uncle Doug!

[@UncleDoug]

Thanks so much, SF :)

[@WillyMcCoy50]

An upper crust Gibson offering from the forties, an outstanding tube-tester from the forties and a Doug video. Do I have to tell you, Life is Good! Thanks Dave!

[@UncleDoug]

You're welcome, KM.......glad you enjoyed it :)

[@amoruzz]

Wow, what an oddball amplifier. Looking at that beautiful wiring work from the factory, one can tell that it was designed and or wired by a military electronics repairman, just beautiful. I've been lucky enough to have met a few electronic veterans in years past that still had a small store that they spent their last days keeping busy. They were always friendly and had great stories to share over coffee. So glad that you got such a rare classic in your shop.

[@UncleDoug]

Thanks so much for the very nice comments, Amo:)

[@danielsaturnino5715]

Thanks Big Dave! And Uncle Doug :)

[@UncleDoug]

You're welcome, Daniel :)

[@richardruth3315]

Thank you for another great video! I have never seen a Gibson amplifier like that one. Very cool amp, and wow it really is in great shape! The tube tester is an exceptional piece as well. I recently acquired a Heathkit tube tester circa 1953, and yep I had to troubleshoot one of those big multi switches. I don't think it was as complex as the one in your tester, but it had enough wires and stages that I almost put it back together and covered it up. I continued with my tinkering nonetheless, and it turned out that is wasn't as tough a job as I thought it would be. I love all this semi-obscure stuff you have on the show, please keep it coming! Cheers from Central CA

[@UncleDoug]

You're welcome, Richard. We will :)

[@newking70]

Danny Cedrone used this model amp on the guitar solo for Rock Around the Clock.

[@UncleDoug]

Very interesting, NK. Thanks !!!

[@rheidtech]

Crazy seeing that sprague capacitor from north adams ma. My parents worked there for 40 yrs. Father in tantelum and mother in filters. Its now mass MoCA. 🤨. Still have some of those caps...

[@UncleDoug]

Wow, RH, you have tube circuitry in your DNA. My grandparents lived in Athol, Mass.....home of L.S. Starrett and Union Twist Drill.

[@rheidtech]

@@UncleDoug nice! I have a bunck of those too. Lol

[@0800338833]

Brilliant video! Thank you so much once again 😀 Gav from England 🏴󠁧󠁢󠁥󠁮󠁧󠁿

[@UncleDoug]

You're welcome, Gav. Thanks !!!

[@jenniferwhitewolf3784]

Wonderful coverage of the tube tester, a full double feature video today👍.

[@UncleDoug]

Thanks so much, Jennifer :)

[@UBOOFTB]

Another GEM UD! Big Dave is awesome too. Keep on keeping on!!

[@UncleDoug]

Thanks, UB. We will :)

[@bobsbarnworkshop]

WOW! My dad gave me his BR-1 back in the 60's to play my first electric guitar through! He had it for his Gibson lap steel guitar...Our first band used it as our PA system and my guitar amp... it was really loud! Lost it in the flood of 1972 in the NE

[@UncleDoug]

What a shame, Bob.

[@bobsbarnworkshop]

@@UncleDoug I blew the original speaker in the BR-1 and replaced it with a regular 12" UTAH 8 ohm... It actually worked pretty well, but at that time I knew nothing about the electromagnet speaker... And my first bass player used a Silvertone 1485, with the 6 - 10" speakers for his bass! I saw you refurbish one not too long ago!

[@henryhunter5026]

Another very entertaining and informative video. The Gibson amp sounded a lot better than I expected, some of those old amps sounded a bit bass heavy to my ears but this one had a very usable sound. The tube tester is a neat little instrument and seems to work well. Here in the U.K. all the tube, (or valve as we say), testers that I’ve seen were made by Mullard , they came in various sizes but I’ve not seen one that small. Years ago I worked for a radio and TV shop and customers used to come in on a Saturday morning with bags of valves that they’d removed from their equipment to get them tested which we did for a small charge per item. Great times!

[@UncleDoug]

Thanks so much, Henry. Thanks for your very nice comments and input.

[@dhix2388]

fantastic looks and sounds/just do whats needed. thanks for your knowledge and time. also love the hotrods. your a talented guy.

[@UncleDoug]

Thanks so much, DH.

[@MrCayoCoco]

Another nice harp driver !! Interesting tube tester to boot ---GREAT STUFF !!

[@UncleDoug]

Thanks, Mr. CC :)

[@sanelimsirovic2039]

I always wait your video it so good I can watch without stopping

[@UncleDoug]

Thanks, Sanel :)

[@exciter2506]

What an excellent video. A two-for-one, amp and tube tester. I am most impressed with that tube tester. Yes, complex, that wafer switch looks to be about 10 layers. It is made by Triplett, of which I cut my teeth on their analog VOMs as an Electrician. Thank you to the contributors, and Uncle Doug.

[@UncleDoug]

Thanks so much, E250. We're glad you liked the tube tester......it's a real gem :)

[@GabrielVelasco]

Great vid as usual.

[@UncleDoug]

Thanks, Gabriel.

[@mutanthifi]

Another great video, and inspirational wiring in that Gibson, beautiful. Takes me back to when I used to do avionics fits. I do feel however, that I must point out that WW2 started in Sep 1939, especially for the millions of people who died horribly before the US decided a) to get involved, and b) which side to join, neither of which was a given until the Japanese made the decision on the US' behalf.

[@UncleDoug]

Thanks for your input, M, but from our perspective, 1941 was pre-war and 1946 was post.

[@SeanKerns]

Love that amp. I have that same DeKalb sign in my barn. I lived in DeKalb, IL for several years.

[@UncleDoug]

Thanks, Sean. My wife is from that area, and I hear a lot about how great the corn is :)

[@snowhyt77]

Thanks for another great vid Uncle Doug! Glad you could get the tube tester up and running. I bought it at a yard sale for $5 about 15 years ago just cause it looked cool, and had it displayed on top of my Hammond A105 organ. Old test equipment has a look that I like. Kinda like sculpture. I did try it out but the burned out light made me think it was broken. I've got the lapsteel that goes with that amp, bet it would sound killer! BigDave

[@UncleDoug]

You're welcome, Big Dave. I hope you're pleased with how your donated gear turned out. I will be posting the Lesmann video in a few days. It really ended up being a wonderful amp. Thanks again, from me and all our viewers, for your generosity.

[@mauricerogerson5825]

Beautiful sounding tone machine!

[@UncleDoug]

Thanks, Maurice :)

[@Slugg-O]

Doug, you are the "Indiana Jones" of amps. I don't know how you find these archaeological treasures but that Gibson is one of the best so far. I agree with your statement about the care and quality of hand-crafted amps. My oldest treasure is a 1941 RCA radio. The wood cabinet is in still in great condition, and even after almost 80 years, I believe would be sturdy enough to stand on. It is all but impossible to find anything like that today. If one exists it's likely an ultra-expensive boutique model. Thanks again for taking us along for the ride.

[@UncleDoug]

Thanks so much, Randy. This is why I have spent the vast majority of my life restoring and repairing vintage items. They were not only built to be repaired, they deserve it :)

[@butchlauer]

Great content as usual, that BR 1 really could have been worse off. For example the speaker being in one piece I found amazing. The bare minimum job of cord, tubes, and caps is outstanding. Cheers to another great find!

[@UncleDoug]

Thanks, Philip.

[@hugomejia593]

Great job uncle Doug amazing production no matter how many videos I have watched seen you surprised me every day great engineer cleaver and skills on your own. I love old school amplification for guitar and bass greetings

[@UncleDoug]

Thanks so much, Hugo :)

[@hugomejia593]

@@UncleDoug appreciate your comments God bless you. Best regards Hugo greetings Doug

[@UncleDoug]

@@hugomejia593 Thanks so much, Hugo.

[@marquis4u2]

Very fun to watch Thanks

[@UncleDoug]

You're welcome, Marquis.

[@abjr2010]

Good to see you using the goodies you got. That amp and it's voltages blew my mind. Never in 50 years have I seen that. Hundred of schematics and nothing came close. Without the schematic I'd really be wondering. Sounded real good. Those 6L6's probably sell for what the whole amp sold for LOL. I used to test tubes at stores when I was a kid. The tube tester was as big as a washing machine HAHAHA

[@UncleDoug]

Thanks, AB. Yes, viewer generosity does not go to waste around here :)

[@barbmelle3136]

From Leo: Great save of a really premium old amp. I have never seen one of those and I have been playing with old amps since the late 1960's. There is a guy that calls himself "D-Lab" on you tube. He fabricates a slick capacitor package by mounting modern caps to a tube socket so the caps stay above the chassis and they connect like an original. I tried it on a tight chassis and it worked great. Might help in a bind sometime.

[@UncleDoug]

Thanks, Barb......for the nice comments and helpful suggestion.

[@jamescarter4175]

Very interesting. Thanks!

[@UncleDoug]

You're welcome, James.

[@drsproc]

Hahaha... it's like opening King Tut's tomb! Awesome vid and thank you for sharing the archeology. Good Stuff!

[@UncleDoug]

You're welcome, Doc. Thanks !!!

[@bullthrush]

Very neat amp and tester. I kept thinking "day old" every time you said "shorts tester". :))

[@UncleDoug]

Thanks, Andrew. Yep, we used to wear our shorts one day, turn them inside out and wear them the next day. When it came time to "change shorts", you simply exchanged with your brother :)

[@montygore]

The old amp sounds great!. I had forgotten about the James Gang.

[@UncleDoug]

Thanks !! Never forget, Monty.

[@romusromulus]

Wow what a layout. Hiwatt eat your heart out.

[@UncleDoug]

Glad you liked it, Sahin.

[@SkyscraperGuitars]

That's a model I've never seen before. Interesting to see all the quirks the circuit has.

[@UncleDoug]

Likewise, SS. I really love these ancient amps.

[@willykanos1044]

If you are going to play with tube amps you need a tube tester. I found one at a garage sale. It was built more recently than this one but was in great shape. I got a bunch of used tubes from someone and tested them all. As such I have a stock of used 12AX7 , 5Y3,, 6V6, and 6U7 tubes that are still strong. I had to trow out a half dozen or so that were too weak. Recently I got another donation of miniature tubes from someone - still in original boxes. I'll test them. I used one of the good 12AX7's to repair an amp for a friend. Nice to have an inventory.

[@UncleDoug]

Yes, it is, Willy.

[@DZig]

Thank you Uncle Doug for another entertaining dive into amp history! It's a shame that bridge trolls can push buttons on a computer and make completely inappropriate comments.

[@UncleDoug]

You're welcome, DZ. Yes, the asylums should be more strict about allowing lunatics to have access to computers :)

[@mikecamps7226]

The BR-1 was my first amplifier when I started to play guitar. An older friend of my father was getting on with age and health issues and my dad was looking after him and he had gifted me a bunch of stuff which included the amp and a 1952 Epiphone archtop with a deArmond pickup that he used to play Jesus music as he was a holy roller. SO at the moment I had no interest in guitar so it ended up in the closet for a few years till after high school I got interested in playing guitar....and broke it out of the closet. I had purchased a used Gibson Les Paul custom black beauty fretless wonder...which was an older style LP custom without the classic Gibson jumbo frets.....and what I used the BR-1 with. So initially it had no hum due to sitting forever considering its a 1940's amp, and it was having this wonderful overdrive response to it when turned up. So as I played it over a few months from time to time considering I was learning, it really sounded great....then it started to sound cruddy. In between, my father was retired and got influenced to relocate to florida, so I was along for the ride and moved. SO while in florida, I explored the amp as to why it was sounding cruddy, and eventually discovered that it was sounding great for awhile for an overdriven guitar response due to the speaker being dry rotted around the surround at the pleat......and went cruddy when the surround finally dry rotted to the extent that it was detached from the basket & just was flapping. SO I was in Tampa and found "The Speaker Exchange" and had the speaker re-coned by them though they said it was an old Jensen but they didn't have the exact cone but had a cone that would work for it since it was an extreme antique at that point since it was a 1940's amp. SO once I got it back and put it back in the amp....yes, it did work again but it had lost that overdriven response I enjoyed....which was the cone dry rotting around the surround. But with that aluminum grill screen and the rear basket kind of concealing the surround from the rear......with an amp of that age.....I wouldn't be surprised if that BR-1 also may have a cone issue from the pulp deteriorating from age. But this brings back memories hahahaha.Post BR-1, I purchased a Fender Twin Reverb silver face master volume amp with the pull out master......which started my tone quest and resulted in me changing that silver face back to the black face specs before all that ever became popular...…The older family friend that gave me the amp & guitar, also gave me a complete wood shop with all kinds of machinery that he had in his basement shop.....I was about 14 or 15 at the time, and he had to sell his house as his age and condition advanced to where he couldn't continue on and had to go to the community "old folks high rise apartment building"......so as I was going through his shop to pack up to move it to my house......I came upon a shelf with what I thought was a home brew wooden cabinet with a speaker in it and the electronics guts...…..and not being educated in guitar or equipment, I DID NOT KNOW......I thought it was a home made item. Years later, as it stuck in my head......it was a FENDER WOODY #26...….and I had thrown it away over a hill in the local dump cleaning out the basement to move the wood shop to my house. Unbelievable…..I wish in hind sight I would have saved it. I had fall into my lap, 2 early vintage amps......some of the earliest examples from the era.....My memoirs......

[@richardweinberger2756]

Great story, Mike . I wonder how this amp would sound with an age-appropriate jazzbox-type guitar.

[@UncleDoug]

Wow......some good old tales, Mike. I wish I had been at the dump that day to catch the Model 26 before it hit the ground. Owning one has always been high on my to-do list.

[@mikecamps7226]

Well the 52 Epiphone archtop was a cutaway type, and the floating period correct deArmond pickup was on a rail so it was moveable from the neck to the bridge or any point in between. That pickup isn't particularly loud and lively.....but is adequate to make sound. The octal pre-amp tubes in the BR-1 aren't high gain, so there isn't that character to it in combination. But it has a warm response due to the plate voltages the tubes are running at. Being a hollow...hollowbody jazz box and the low output pickup and the amp gain structure.....there wasn't any intense aspect of generating feedback. But my amp in particular with the humbuckers hitting it and the speaker being deteriorated at the surround imparted a nice fuzz type overdrive.....not so much from the electronics but from the speaker being compromised . But with the BR-1 and being a period piece, there is a mic input which has a higher gain than the instrument channel. In that era it was common to have the amplifiers have the dual role for PA or multiple instruments as opposed to being a dedicated singular instrument amplifier.I'm more familiar with the 9 pin pre-amp tubes than the old style octals..….but I have never noticed if there are any commonly used octals that have the gain equivalent to a 12ax7. The octals usually are more comparable to a 12at7 or a 12ay7.But as with recordings being a window in time, I'm sure there had to be artists that used a BR-1 and a jazz box guitar.....post war big band era/jazz era.The peculiarity's of the period in the electronics is the style of phase inverter being used for a class AB push/pull amp and the plate voltages and being cathode biased and the rectifier tube.Its been eons since I pulled up the schematic for the BR-1, but I can't say that the electronics rate as being exceptionally special for guitar the way that a late 50's tweed fender deluxe circuit would be for guitar or the holy grail 5F6a tweed fender bassman circuitry. Though as I write this.....and recently having built a harmonica amp for a harp player..….it might be viable as a sleeper harp amp but that's something I'll have to look in to.Usually the fender 5E series amps with the cathodyne phase inverter are the sweet amps across the board.....and the 1960ish SANO amps have the right points with the cleaner type power tubes.....I think they are 7591's with 9 pin pre-amps and cathode biased and cathodyne PI with a cathode follower tone stack but baxendal tone controls. The SANO amps use a 500K pot for the volume controls so its like getting half the volume of a 1 meg pot that's normal in value for a volume pot....where the signal is separated from ground at wide open by 1 meg resistance so no signal gets lost being bled to ground and hence gain. And strangely enough, SANO used a 220K plate resistor on the pre-amp primary tube, so the gain structure is high...where typically it would be a 100K plate resistor.

[@mikecamps7226]

I no longer have the BR-1 amp not the Epiphone arch top...….though I acquired a Gibson L-48 student archtop with another period correct deArmond pickup system......and I think its a 1952ish vintage and has flat wound strings on it that came on it when I acquired it out of a closet...time capsule. I don't play it, I just have it......not a museum piece where I just look at it......I just have it and I look at it hahahaha.I'm not particularly a collector, but I might have around 40 guitars......mostly solid body but I haven't acquired a 335 yet and remotely if I were to go for a hollow body...I might consider a 175.I'm mostly a blues guy...dirt and grit and overdrive, though I have recently done some work for a couple of jazzers…..loud and clean and warm......so it was a rethink as opposed to how I normally voice amplifiers for clients, and had a harp guy as a client for a build and now have another harp guy that wants an amp built for him too.....and that's a completely different bird to tune and voice.....since I don't play harp hahahaha

[@freepress8451]

Classy features on this vintage gold

[@UncleDoug]

Thanks, Nic :)

[@matthewb8229]

For several years, I hand tied lacing cord in electronic drawers in the Air Force. It's a lost art. Zip ties are usually used now.

[@UncleDoug]

I really like the look of lacing cords, gathering wires into cables within the circuit. You're right.....it is a lost art.

[@brianyork5510]

The Triplett instrument company was founded 1904 in Bluffton OH. The town only has a little over 4000 people, but the company remained there until they were acquired by Jewell Instruments in 2007. At that time Triplett was relocated to Jewell’s manufacturing facility in Manchester, New Hampshire

[@UncleDoug]

Thanks for the historical review, Brian.

[@jeffm8122]

Just like the old days at the movies when we got a double feature. I really like the construction and internal layout of Fender amps, but I think there is something special about the early Gibson control panels. As you remarked the layout in this amp is also very well executed, ever single wire planned before any soldering was done. I think the low plate voltage is due to the 826 ohms series resistance of the speaker field coil plus the filter choke rather than the 20K shunt resistor which would only draw about 8 or 9 mA. The very low, 120 ohm, cathode resistor being needed to obtain a reasonable bias voltage. Wallace Marx Jr's book on Gibsons shows a BR1 without the filter choke. Unusual design but a beautiful amp just the same. I note you got one nasty comment. They remind me of something unpleasant you step in and need to scrape of your shoes before entering your home. Thanks Doug for again bringing us your knowledge and skill.

[@UncleDoug]

Thanks so much, Jeff, for your nice comments and your knowledgeable input. I haven't seen the nasty comment yet, but have my shoe scraper handy :)

[@renegade44040]

It does sound good!

[@UncleDoug]

Thanks, JJ :)

[@jorgemellooliveira9611]

obrigado mestre ótima publicação

[@UncleDoug]

You're welcome, Jorge :)

[@jorgemellooliveira9611]

@@UncleDoug Thanks I feel good

[@UncleDoug]

That's what counts, Jorge :)

[@mattwicks4788]

Those knobs are very cool.

[@UncleDoug]

I thought so too, Matt, and still in great shape :)

[@marcosa3145]

I remember when I was a child in the early 70's my dad took the tubes out of our television and took us with him to a store that had a tube tester. He tested the tubes and under the machine, new tubes we're stocked. I remember him looking for new tubes to replace the bad ones. Sadly we don't see that anymore.

[@UncleDoug]

Thanks for sharing this fond recollection with us. I had similar experiences and, like you, really miss the good old days.

[@marklange8894]

Just a follow-up on the Hagerman Vacutrace. As Jim Hagerman told me by email. ”they only come up for sale when somebody dies” the one I have was the first unit off the production line when he was selling them. Jim Hagerman is an audio guru and designs and builds super hi-end hi-fi gear, mostly one at a time because he is so picky about the equipment that he sells he doesn't trust factories to assemble it. The Vacutrace was designed specifically for testing and matching tubes for audio amps. It is a mostly analog design because as Jim put it. You don't get anymore analog than a vacuum tube. I found a website online about ten years ago and ordered one. A month or so later when I inquired about my order I received an email from Jim Hagerman asking me where I had ordered it because they had been out of production for ten years. I gave him the details and he told me that the had the pre-production unit on a shelf in his office, and had enough parts in his storage unit to put together a complete set of adaptor boards and would sell that one to me if I was willing to wait a few weeks for him to rummage through his storage and find where he had put all of the leftover parts. He went through the unit off of his office shelf and made sure it had all of the final production updates and tested it against the 3 Vacutrace’s he uses when testing and matching tubes for the hi-fi equipment he now sells then shipped it to me. He is a great guy, has a background in everything from microwave communication design to very high power audio systems for theaters. In an interview, I read he was quoted as saying that the most important thing in an audio amp is making it quiet. He said he learned that in the theater audio business, running multiple 5000-watt amps at full volume, with no audio signal going through them, without hiss in the speakers. He said that is a common occurrence in movie soundtracks. So he set out to design high-end hi-fi systems that could do that. Along the way, he designed the Vacutrace for himself and then offered it for sale, even in kit form for a while, but he was about ten years ahead of his time. It was before most people began to realize that tube audio really sounded better than solid state or digitally reproduced audio. So the Vacutrace kind of flopped because there was only a small market at the time. He made two models, a desktop and a portable. (I have the desktop model). When he finally sold out of the small production run he had ordered he decided that was it for that project. He also said that the kit version was a big mistake because he felt like he was having to hold the hand of almost every person he sold one to. Any little problem he would get a phone call. He said it was much easier, and in the long run, cheaper to build it himself and ship it out than to spend hours on the phone walking people through the build. There is almost nothing on the web about the Vacutrace but I have seen a video of a major tube seller’s testing lab for matched pairs and quads of 6L6’s an 6V6’s and right in the middle of the room amongst racks of tubes burning in was a Hagerman desktop Vacutrace and an oscilloscope, with two sets of pentode curves in the screen. I had plans of offering a tube matching service when I bought the Vacutrace but my wife’s health put that on the back burner. I started thinking about how many perfectly good tubes get tossed out just because the amp owner has no way of testing the overall performance of the tube. Tube testers will give you an idea of how good the tube emissions are, but only a curve tracer can show you how well the tube is actually working over a wide range of grid voltages. Also, a curve tracer is the only way to truly match a pair of output tubes over their entire operating range. Maybe I should rethink the tube matching service. I don't know. The Vacutrace I have is the only one with a blank serial number plate which I thought was kind of cool. I once again got long-winded, but it is a really neat piece of gear. Have a great weekend and say Hi to your wonderfully artistic wife and the kitty’s for me. (Oh I was speaking to another ”displaced West Texan” yesterday at a local store about all of the rain we have had lately and found out I am not the only one who is sick of it, and this blasted humidity, as I write this at 10:49 AM it is 83 degrees outside and 68% relative humidity. Oh how I would love about a week of 5 or 6% humidity. 19 inches of rain this year, over 4 inches in the last 30 days.) never thought I would gripe about rain. :)

[@UncleDoug]

Thanks for the excellent and very informative review of the Hagerman Vacutrace, Mark. Both he and the device sound totally first class in every way. It's supposed to hit 100 here this weekend, but generally dry as a bone. They released water from Elephant Butte and Caballo (for irrigation), so the Silvery Rio Grande is flowing once more. Life is good in the Great Southwest :)

[@smasica]

Funk #49; sweet. Nice little sparkle on that amp. I be likin' it.

[@UncleDoug]

Thanks, TM :)

[@srtamplification]

I have an NRI tube tester as well. NRI came to existence in the early 1900s in order to train radio repairmen. It then branched out to telephone, TV, computers etc. I took an electronics course through them in the early 90s. They went out of business in the early 2000s. They just couldn't stay in business due to the lack of demand for electronics repair in the new disposable world.

[@UncleDoug]

Thanks for that information, William. It's a real shame that a company with such a long, distinguished history can no longer survive.

[@goodun6081]

I have some mail-order course books for electronics repair that came from NRI. They were written and assembled very logically and likely would have given anyone who stuck with the courses a very good grounding in electronics Theory and practical knowledge.

[@srtamplification]

@@goodun6081 Yes. I have them as well. Probably 100 of them or more. Very good course in its day. Sadly, not much of a demand for those skills today.

[@jaymichaels5187]

Not the best sounding Gibson amp but that military spec style wiring was pretty impressive, even Harry Joyce would have liked that. All in all, another great video, Uncle Doug !

[@UncleDoug]

I think for what it is, it sounds great, Jay, but to each, his own :) Thanks !!!

[@stefangies5570]

Excellent video ! A+++++++++

[@UncleDoug]

Thanks, Stefan.

[@joseislanio8910]

The dents in the aluminum grill can be fixed by smashing it several times with a rubber beach slipper or something like that. It won't damage the grill, but the dents will become less apparent. I used to do it to repair the aluminum grills in parabolic antennas years ago.

[@UncleDoug]

That is an original solution, Jose. I will keep it in mind :)

[@fredgarvin4482]

speaking of techs coming from the military. i have a quick little story you might like. i became interested in tube amps years back and i was buying all kinds of old books from ebay. one lot of books i got appeared to be a box of stuff from someone i can only assume has passed. it had TV repair manuals and tube reference books and etc. i don't recall now how exactly how i determined it, but from the stuff that came in the box it indicated that the former owner had started off in the army air corps. sadly i life got in the way of me continuing to learn to work on build my own amps like i had intended. but i been getting the bug again lately

[@UncleDoug]

Thanks for your comments and input, Fred. We hope you remain interested in tube amps and continue to learn.

[@samuellord8576]

Hi Doug, you really outdid yourself on this project! Humor, kitties, circuit comments, clear as a bell, pristine unit... the ultrafecta. Superb job! Two comments: 1) That grill blocks a ton of the direct radiation! Now it sounds _great_, and clearly that gossamer-thin surface acts as much a diaphragm as the woofer cone itself. In a perfect world, one could have another, less-impeding grill (or no grill) to substitute with a quick change-out. I just wonder how that would sound. (It could easily be worse!) 2) The original wire bundling is very fine for many purposes, but I wonder how much crosstalk and intermodulation penalties result. Of course your careful wire twisting, right-angle overlays, robust grounding, and use of shielded wires has been very successful. But compared to the original wire layout, I wonder what an ideal rewire like yours would do for noise, distortion, and tone. The first two should certainly benefit, the last maybe not. 3) I meant to add, do you have favorite make and model (not value) volume pots? 4) Oh, and what were those lovely tunes at 24:00 and 25:00? I'm ignorant of music. :( Cheers, Sam

[@UncleDoug]

Thanks so much for your interesting and knowledgeable comments, Sam. I tend to buy the inexpensive Alpha pots from Antique Electronic Supply. They are spot on as far as taper and resistance.....and they have a nice rotational feel. Ollie & Jack often play tunes they have composed (in between cat naps and catnip binges). I hope you enjoyed them.

[@dwightbehm4747]

Thank for another fine Vidio Uncle Doug on Utube. Something interesting. I have an old chemistry book printed back in 1973 a friend gave it to me about 8 or 10 years ago never read it untill About 5 years ago an article on rare earth metals in the book said the strontium or barium metal coatings on the cathode of electron Tubes increases the emission of electrons From the cathode By hundreds of millions of times. Perhaps when tubes get weak the metal coatings are starting To strip off. There are about 5 to 10 defferent Kinds of metals used in the making of Electron tubes. I wish I would of been this fastenated when I was A kid I would have learned alot more back then fastenation and Pashion brings out the Best in retension of knowledge. Dwight

[@UncleDoug]

It's great to hear that your are reading and studying tube technology on your own, Dwight. It's the best way to learn. You're exactly right about what causes the aging of tube cathodes.

[@ronnewby3196]

great job ,also like screw in power strip ground.

[@UncleDoug]

Thanks, Ron.

[@Calcouk]

Great video and bonus Uncle Doug. Thank e kindly. Given that the amp cost all that money back in the day, is it possible reliability was critical. I know that even among "boffins" building tube computers in England, "thermionic valves" or toobs, were considered unreliable in the 1940s. It took a guy called Tommy Flowers who worked for the GPO (The UK Telephone company) as an engineer to put them right when he building Colossus he said .. "Just leave her switched on permanently and turn the voltage down during quiet times .. but NOT off!" Tommy was right and Colossus did her job reliably.

[@UncleDoug]

You're quite welcome, Calco. Thanks for the nice comments and historical facts.

[@GuitarSmith.]

It sounded like this amp has quite a bit of clarity, real nice presence without being brittle.

[@UncleDoug]

I agree, Martin. It's a really nice amp.

[@SeanKerns]

Love the tube tester feature. I have an even smaller one, about the size of a backgammon set, but it must be 50's or 60's, because it's got a 9-pin socket. I picked it up at an antique mall for I think about $25.

[@UncleDoug]

That sounds like a real gem, Sean......at a very reasonable price :)

[@SeanKerns]

@@UncleDoug Your video has inspired me to open it up now and see what's inside. I bet it has some caps that need replacing.

[@UncleDoug]

Get her tuned up, Sean, and back in service :)

[@MrBrymstond]

These amps would work great in the studio along with the new gear. Make Music Great Again.

[@UncleDoug]

Yes, they would, Mr. B. Thanks !!

[@rheidtech]

Great vid u d

[@UncleDoug]

Thanks, RH.

[@1112223333111]

27:00 you may or may not know you can "zero" the meter with the flat tip screw on the front. Use a big but thin tip or knife and gently creep the scew to set the resting point on 0. Both these items are very nice and from a time to be alive

[@UncleDoug]

Thanks for the input. I agree about the "good old days"......especially the way things are going lately.

[@1112223333111]

the lawlessness is ridiculous God Bless

[@steelcity321pb6]

Wow Douglas, those two pieces of equipment are definitely ‘substance over style’: as you indicated, it is so often ‘style over substance’ these days ...full of wind and.... well, yes, they might be ‘smart’ but I guess we all know what the are full of LOL. I have to say, that Gibson amplifier has a superb tone - I like it very much. The valve tester is an interesting piece of equipment. It is very likely it was designed for use in the field. Certainly a handy piece of test equipment ready for use at a service technicians bench, as well as inside a customer’s home, and not taking up too much space under a bench when not in use, and also alongside televisions, and radios in the back of a service vehicle. Where I once worked, we had similar types, but ours were a little older (around mid-30s):and they too did not include B9A, B8A, or B7G valve bases. They were manufactured by Taylor - you might not have heard of that brand of test equipment. Thank you for another interesting, and informative video. Phil.

[@UncleDoug]

You're welcome, Phil. Thanks for all your nice comments.

[@bradleysmith4409]

BAD ? GOOD Now that is a quality index!!!

[@UncleDoug]

Yep :)