I love old tube amps. If you dig them as much as I do, this blog is for you. Guitar, Hi Fi, recording gear, nothing beats the warmth and character of this antiquated technology. Shared here are tips to keep your much loved old amps in good shape, and tips how to improve your new gear. Have a comment or suggestion? Leave it here! Thanks for reading!
Simple job today, just re-cap the power supply. Amp was running quiet but now it just sounds better with a stronger low end. It will be mated with a beautiful P-Bass soon and ready to cut phat tracks. You have a studio? It's not a serious studio without a real B15!
Stick o' dynamite cap, 30uf@600v, replace with a C.E. Manufacturing 25uf@800v stick:
Also replace the big can with a C.E. triple 40uf@525 volt can.....
I left the audio circuit alone. I like these green .02 Cornell Dubilier capacitors. They're still good and the amp sounds great! Ampeg in those days didn't skimp on small parts. They are built to last.
My client and I bought this amp from a new shop in Brooklyn called Rock N' Roll Supplies. Great place and they have a great tech working there. Give them a visit! Some mighty nice amps hanging out there and reasonably priced!
Just finished this one, a very rare Magnatone A-646 amp from about 1951. This one us a real gem and is visually striking as well.
I bought this amp by mistake on Reverb this winter. I put an offer on a Varsity that I wanted as a backup to my main one and the owner declined. It wasn't a bad price and I love those early Varsity amps and it was pretty enough that I was willing to pay his price anyway. This one came up in my feed and I was curious so I put an offer on it. The owner said he would think about it. First amp wound up coming through at my price so I bought it then.......so did this one!
This one arrived first. It was noisy, had some really poor tech work done to it so I got it going. I wasn't all that impressed with it though and even after re-capping the power supply it had a considerable amount of hum. I even added another filter stage. I knew there were other solutions, maybe filament, maybe ground loop but I shelved it. If it's mine I tend to just put it away and forget about it.
So today I did a better re-cap, with a nice expensive C.E. can, an additional filter stage and while it got better and was certainly tidier, still hummed at an unacceptable level. So I disconnected the center tap of the 6.3v filament and added a hum balance: 2x 100 ohm resistors, one on each side of the filament, the other sides both going to the cathode bias resistor on the 6V6 tube. Looks like this:
When I brought this up on my Variac I thought "dammit! I killed my amp! Time for more troubleshooting!" I just wanted to be done with it. But reality is, the amp is just so quiet now! Hum free with only a little bit of noise when it's turned all the way up.
This amp I believe is the precursor to the Varsity Deluxe I reviewed here. Similar circuit, 40's style box, single 6V6 and 5Y3 but driven by the darker more euphonic 6SL7 tube rather than the snappier 12Ax7. It has a single 8" Alnico 5 Jensen speaker.
More pics:
How does it sound? Like the early version of the Tweed Fender Princeton. It's a similar circuit, but this plays cleaner and more articulate. It has a big sound for such a small box, warm but not fuzzy. Ideal Wes Montgomery or Charlie Christian sound. I'm a big fan of the Magnatone amplifier, especially the early ones. They are a bargain. I may sell this one but not for cheap! I like it a little too much.
The only drawback is the 6SL7 tube can be microphonic. If you turn both the volume and tone all the way up it may sing a song. The 12AX7 is a better tube for guitar amps. You could simply use a 6SL7 to 12AX7 adapter available on EBay, or you can just roll a little bit of the tone control back and enjoy that big warm sound.
If you like something different, give one of these a try! They are lovely little amps!
JB
8/29. After tracking with a Les Paul all weekend I've decided this is my best sounding amp. Bigger tone than a tweed Champ, smoother top, goes to tape beautifully! It's a keeper! Do look out for one of these. I did some reading about the hum and one tech mentions he struggled with his as well. he resorted to installing a big ass choke and extra filter stage. That should do the trick but try the hum balance first along with adding one filter stage. Quite happy with the results here. JB
Here's my main guitar. I built it on my rooftop when I lived in Williamsburg Brooklyn 3 years ago:
Photo by Starina Catchitoorian:
Beach gig!
I started out a Jimi freak when I was 14 years old. So naturally I played a '69 Maple cap Stratocaster ($750 in 1990!) for years. Trouble with a Strat, something Dave Navarro said to me: "Trouble with a Strat is you wind up playing Strat things on it...." They do have a way of commanding you to play certain things. So during the grunge scare of '92 I bought my first Jazzmaster, a beat to death 1964 model(100% original, $750 in 1992!). I played that guitar for years. Best part was I didn't know how to play a Jazzmaster so I really feel like I started to find myself on that guitar. It wasn't until '99 at a guitar show in Portland that I bought my first Telecaster, a refinished black 1966 maple cap model ($750! Notice a trend??) that was light as a feather and trust me, I really didn't know how to play that guitar. I sold it in 2003 and doubled my money. It gets played in church now. I've bought and sold a lot of guitars over the years and that is the only one I regret selling. I had the bridge pickup rewound by Fralin to make it hot like an early 50's model. That was a great guitar. Rent and debt! Bah!
But the guitar I've always wanted is the Fender Esquire, namely ones made in the early 50's. They cost a lotta dough now. I have played some that were not to my liking at all and priced about $15k, and played some that if cost were no object I'd just pay whatever it takes.
To find one in Copper? There may not be any. There are only a handful of copper Telecasters in existence. I'm not too keen on the new Fender product, the relic or reissue series. Good stuff but I'm way too picky.
And really I'm totally happy with this one that I built. I have about $400 into it! It gets played every day.
The neck is just an Allparts V. They're great. I may upgrade to a Musikraft cause they are better and I can afford it now but like I said, this guitar keeps me really satisfied as is.
The body is pine, bought from Clearfork Designs on EBay. His EBay name is Ohlar. It's super light, about 3 pounds and a few ounces. I met the guy who makes them at the Dallas Guitar Expo. He's just a great guy. Super warm and friendly. You can tell when that kind of vibe goes into something one builds. I bought another body from him there that I am going to do something with next year. It's lightweight ash.
So I used Guitar Re-Ranch products to do the finish. Desert sand undercoat, copper then clear. They make great stuff. My only error was not doing a sanding sealer. Oops! Well, the grain shows through now. Fender wouldn't let that happen, but I'm not Leo!
After 3 years it's getting pretty worn!
No need for relic stuff, these are my scars and this is my story. I did the silly dowel holes as well, just details:
Finishing I did the lazy susan nail hole method Fender used to use. It's already developing that 'Fuller Tan' visible when you remove the control plate:
I went with Fender hardware and a Mojotone 50's pickup.
I really like Mojo pickups. This is the heart of the Esquire. That simple 1 pickup design forces me to play for real and extract what I want out of the guitar buy using my hands creatively. If I want mellow I need to find mellow. Gnarly is less of a challenge!
I used all CTS pots and CRL switch, the knobs are Daka Ware from the 40's, bakelite and oxblood colored. I like the way they look with the copper body. The switch tip is Daka Ware as well, oxblood too!
The pickguard is bakelite, did the whole lacquer paint circle thing cause I can! The decal I bought from some European vendor. It's pretty accurate!
So this is my baby now. My main guitar. I think it's the simplicity of the Esquire that I like the most. It forces me to find melody, be creative in my playing since I'm not fiddling with tremolo arms and pickups. I just play the thing!
A bit of the guitar in action in a 110 degree room!
And me and my friend Starina....she plays a copper Danelectro. These go together well!
Here's an interesting amp. A 1954 5C2 Wide Panel tweed Fender Princeton.
This was an internet purchase what was serviced by the previous owner. I didn't take any before pictures but, the amp worked fine but the work was comically sloppy. I get a lot of work cleaning up poor jobs.
The other bits: this is a really great amp. It was loaded with a cheap Electro Harmonix 4 ohm speaker and a cheap Triode Electronics output transformer. Not bad stuff, but to my ears, it was rather flat and uninteresting. It was also loaded with Sprague Orange Drop 715 caps. No, no, no. Filter caps were decent quality but sloppily installed.
So I loaded it with Mojo Dijon caps, a 60's 8 ohm Jensen C8R (I effing love these speakers!) and a Mercury Magnetics '55 8 ohm tweed Princeton transformer.
C8R: Brown is Beautiful!!!
I come across these speakers on EBay all the time. Best lil' secret though I suppose if I get more readers everyone will want one. Not useful for Champs, these are 8 ohms. But for my GA-5 and old Magnatone Varsity, it's a match made in heaven. They were often used in organs as midrange drivers so they are usually in great shape. People played polka and church music through these babies, not blues and rock n roll!
Yes I know it's not an alnico speaker. I do love a good alnico but as someone who plays out live on tiny amps, I like the way these project and hold together. I like the clarity I get. Try one! Couldn't hurt!!!
Better interior though not final:
I replaced the original 250k 2 watt load resistors which were noisy with new carbon composition 2 watters. Also replaced the cathode bias resistor and power resistors, typically they drift far out over time and these were no exception.
This particular amp has one transitional feature. They were loaded with a 6SC7 tube, then a 6SL7. In this amp the socket had an adapter to put in a 9 pin miniature socket so it could be loaded with the more modern 12AX7. This was factory. And not unusual is the tube chart simply has the 6SL7 tube crossed out with a ball point pen and 12AX7 written in. Leo Fender liked to use whatever parts he had left over till they were gone. Very much in line with his practical sensibilities.
I took out the "meh" output transformer and loaded it with a classy Mercury Magnetics FTPO-55-8. From my research on these amps, they were 8 ohms. Better to not be lazy and use your off the shelf 4 ohm Champ transformer if you are going to get this right. Just my opinion. More expensive, yes, but totally worth it. The amp came to life after installing this and the Jensen speaker. Big, warm and round. I fell in love with it right away. With a Les Paul or a big Jazz Box it's heaven.
The Mercury transformer is bigger than what was in there, and I suspect the original may have been mounted to the speaker. But the good thing, there are some factory 'mystery' holes in the chassis that mounted diagonally the transformer mounted perfectly.
These are quite different than the more sought after late 50's 5F2 model. This one is a 5C2.
The preamp arrangement is radically different than a 5F2 or 5E2. Between the first and second stage in the preamp you have a 250k resistor connected to a 75k resistor that is going to ground. It's a bit like having a potentiometer in that spot and it's set to 1/4 volume. Just for fun I tried opening this up to see if I could get more gain. The amp simply became unstable and started motorboating. BUMP BUMP BUMP BUMP....... I put the resistors back the way they were. Looking at the schematic this may work with an additional stage to the power supply, this sound typically happens when you have a bad filter cap or too little filtering. Could go to all that trouble or...simply accept this is the way this amp is and what it is is not a later one. Why not have an amp that plays cleaner? It has such a beautiful tone. For my style, it's perfect and I kind of want to build one just for me.
You can see the evolution in this amp going from the old 6SJ7 circuit, which has little gain, to the later rock n roll nasty later 50's 12AX7 version. It sits right in the middle of that evolution. The tone is more relaxed than a later version, but has a bit more punch than the earlier version. Right now the owner claims it's his favorite. I can see having one and feeling the same way. Great little rare gem!
This is a little post about the legendary Sprague Vitamin Q paper in oil capacitors. I used to have dozens of these and at one point used to swap caps in and out of my hi fi amps when I had that kind of time. I was never all that impressed with the Vitamin Q caps in the past myself but decided to give them a go again now that I only have one system that I know quite well.
These arrived yesterday and I threw them in to my lovely single ended 45 tube amp.
When you have such a simple circuit like this, every little change makes a difference. For instance, the 6SJ7 driver tubes pictured lived in this amp for a day. They are Sylvania. Really nice tubes. I prefer my 5693 RCA Red series tubes by far so they went back in the box! The Sylvania version I love in a guitar amp. Big, open sound but for my hi fi I found them a bit harsh.
The signal caps were Sprague polyester PS type, .1@600V. I hate the 715P series that has been so popular for the last 30 years. The 716 is better but if I gotta use Orange Drops they gotta be PS types. I find them to be smooth, detailed and musical. Plus they are warm which I need and they don't sound harsh like the beloved 715.
Now the 715 in a mushy old amp? That can work. Not saying they are trash, remember, everything is a relationship so they work for some amps just great.
So when I audition a new cap, tube or transformer, the first thing I do is pick a record I've been listening to for many years of my life, preferably something with vocals. In this case it was "Rastaman Vibration" by Bob Marley. First question is how does Bobs voice sound? Can I make out the words clearly? Second is how does Aston "Family Man" Barrett sound? Does his bass sound natural.
First listen is terrible. No definition, crap bass. But, the amp had also been on a mere 3 minutes. When auditioning a cap let it burn at least an hour. When you rebuild an amp, you must give it time!
So I went about my business and came back to it after a few hours. Liquid.... That's the word I use. Bobs voice sounds clear and natural and the bass is big and fat. The bass however, does have a bit of flab I didn't notice before. These are bigger caps than what I had in there (.15 rather than .1) and I could go down to .05 and get my bass needs met. But I will continue to listen to records and see if it works itself out. As I recall, these Vitamin Q caps got better with weeks of use.
So the jury is still out. Do I spend $30 a cap on Jensen Paper in Oil? Are those worth it? (the answer is YES in my opinion. Those sound beautiful.) Or do I keep on keeping on with these surplus store gems? Time will tell and I will tell you later. For now I dig them about 85%.
And on a final note. Are paper in oil caps worth it in your guitar for tone caps? No.... Those merely bleed a little high end to the copper pipes in your walls. You can get a 50 cent ceramic to do that job. That's all marketing ladies and gentlemen......
JB
And instant update....That was fast!
Listening to my favorite Coltrane record, "Crescent". Side 2..... I wore out my first copy ,I love this side that much.
Jazz has a wonderful way of mixing itself. At least in a quartet fashion. The bass and low drums are the lows, the piano and sax are the mids and the ride cymbal are the highs. Coltrane sounds like he's hanging out in my little apartment playing. How the hell did he get that sound is beyond me! So warm and beautiful on this record. Jimmy Garrisons bass has authority and clarity and McCoy Tyner....crystal clear. The second song on side 2 is called "The Drum Thing". All about Elvin. Such a beautiful, dark drum sound. That piece moved me to change the way I make music. Oh yeah, this is about some caps.....they've been burning in all night. I'm in love.......
This arrived in the mail today. An early 60's Gibson GA-5 Skylark. I love these amps. It's to me, a Champ killer. The Fender stuff is built much better but some of the late 50's to early 60's Gibson amps just have such a great thing going on.
Typical 3 tube 5 watt design: Single 12AX7, 6V6, and 5Y3 rectifier. This one came loaded with a nice RCA 6V6 and 5Y3 and a great nasty sounding GE 12AX7. It was also 100% original. I changed the electrolytic caps and installed a grounded power cable for safety.
I've bought a few of these as fixer uppers and flip them like a burger. They are easy for me to sell cause they are just that good. A bit wider and more open sounding than a tweed Champ and much less dough. I may keep this one, my last one I was bummed about selling.
Now, in the pictures. Notice how filthy this amp looks. Fresh from the barn. When I turned it on it crackled and popped, the pot was filthy. Not sellable in my opinion. I would have bought it at the asking price, no problem but that's cause I can fix it good and proper. If I was just a guy who didn't have those skills I would have turned away. I bought this from the worlds largest guitar store online. Won't mention the name but you know who I am talking about. I did a stint with said company and was baffled by their treatment of vintage gear, good vintage gear like this. No effort made to clean or improve. I suppose somewhere corporate sees that extra effort hurts that bottom line. I like to make money. I like to make as much as I can. It doesn't take much effort to clean something up. People like it when they don't need to worry and don't have to do anything except negotiate a price and be done with it.
But that's the nature of some big ass companies. Too big to care. It's okay to get big, but never give up the caring part! There's money to be made there and more importantly, there are people make happy.
And here's the schematic for you tech heads. Ultra simple signal path. LESS IS MORE!
So what do I like about these over a Tweed Champ? Well, first, I ain't gonna lie. The price! Tweed Champs to me are simply overpriced. No fun for me. Second? I just got back from playing this at my practice space for 2 hours. These amps tend to not fuzz out as much. The notes articulate better for me. Pick soft and you get a lovely clean sound, punch it and it sings, nasty distortion but....clear. I can hear all of the notes in each chord. It really sounds like a cranked Marshall in that respect.
This particular amp has the original .022 famous Bumble Bee Sprague capacitors. Yeah, they are leaking. Can tell by the fact that the volume pot scratches slightly from top to bottom. A little DC on that, and also by the way the notes decay. I may change them and sell those to a rabid Les Paul fanatic. But for now I don't care to change anything else. There is something I like about the slight trashiness.
So what is the difference between a GA-5 Les Paul Jr. amp and a GA-5 Skylark? Electrically, there is no difference. Same great Jensen 8" speaker too. The cabinet is slightly different and the Skylark says "Skylark" on it. The Les Paul Jr amp is a bit earlier, the Skylark was made in the early 60's.
Here's a Skylark I sold 2 years ago:
And the earlier Les Paul Jr amp:
If these amps were mint you would see that dapper Gibson logo on the front. The Skylark had it on the grill cloth, the Les Paul Jr amp has that lip across the top of the cabinet where the logo went.
If you are considering one of those sad GA-5 Reissues, don't bother. You may find one of these for about the same money and these are simply better amps. And if you find a dead one cheap, they are so simple it won't cost much to get it going again. Even the higher priced ones are worth it as a tool. Nothing beats one of these in the studio. Pure, simple, direct and awesome sound.
