Quite possibly the greatest aerial photograph ever taken. Photographed by Alfred Buckham only 17 years after the first manned flight, this image must have been a thing of wonder, truly mind boggling at the time; almost 100 years later, it's still breathtaking. To learn more about this photo, and about pioneering aerial photographer Alfred G. Buckham, go to the National Galleries Scotland website.
Most online reproductions of this photo have been artificially tinted in a faint sepia tone in order to, presumably, make the image seem aged. Although it may not be apparent to those who choose to ignore the obvious, keep in mind that when this picture was taken, it was new, and not old. It looks a lot better in black and white.
Every story has a beginning, and this one starts with an ugly little speaker cabinet that no one wanted, until it found a loving home:
Long ago, possibly in a faraway land, this cab started life as a solid state guitar amplifier, and there's no way to know what brand or model it may have been. At some point the amp circuit died, and its owner removed the amp chassis and tossed that into a dumpster. Then, he put in a really unattractive hand sawn plywood baffle that filled the entire front of the cab. It was even uglier than it is now, with an unpainted baffle, no grill cloth, and a chunk of MDF hammered into the back opening and glued crudely into place.
When my friend David was rebuilding a late '60s Bassman head, he needed a speaker cab to test out his repairs and circuit mods as he went along, and found an ugly particle board cabinet on craigslist, really cheap. Besides its unsightliness, one reason it was cheap was that it didn't come with a speaker. I contributed an old Cerwin Vega 12", and that combination got David through his amp restoration project. Later he put the Bassman chassis into a beautiful JD Newell 2x10 combo cab, but that's another story.
Over the years, this ugly cabinet has had numerous 12" drivers in it, for auditioning various speakers, and as an extension cab for testing other tube amp mods and repairs, and it became known as The Test Cab. Which sounds better than The Ugly Cabinet. The Test Cab spent time both here and at David's shop, and when he moved back to Mass, I inherited it.
Out of all the 12" speakers that have been in The Test Cab, one of the best tonal combinations has been with an ugly old vintage speaker that no one wanted:
That's a Fender labeled CTS, original equipment in an early 1970s Deluxe Reverb Amp. I had replaced it with a late '60s Jensen C12N; a friend in Colorado now has that amp, but doesn't want the CTS back at all - he's a guitar player, not a vintage hound or collector. I'm not a collector either, but old stuff seems to find me, and I always have too many 12" speakers. I've tried selling that '70s CTS a few times - Reverb, eBay, craigslist, and nobody ever wants it. A real 40+ year old vintage Fender speaker that still works well and sounds great, for a low price, and no one wanted it.
That is, until a couple months ago. I put the CTS up for sale again on local craigslist as a combo deal with The Test Cab, since there's now more than one empty cabinet in my shop for testing. Only $35.00, and no bites for over two weeks - until someone answered the ad, and asked if I was up for a trade, and sent this picture:
Hey, I've seen that Epiphone Les Paul Special II before, and I know that out-building, which is a cozy music studio in a little town a few miles west of here. I had some clue who had answered the ad, and I replied: John, you don't have to trade that Epiphone, you can just have that speaker cab, I'm happy it's going to a good home.
But John loves to barter and trade for stuff, almost as much as he likes making music and building unique and interesting guitars. He wanted that ugly old cab with the unloved speaker, and wouldn't accept them as a gift. So I did end up with that funky Les Paul, but I took all the hardware bits off and gave them back to John, keeping just the control pots and switch.
Although these inexpensive low-end Epiphones are made of some strange space-age faux wood, they're really okay, except for the low-quality tuners, bridge, and pickups. This particular guitar had a neck I really liked, with a chunky, solid feeling '50s profile, and no fret wear at all. Almost unplayed, and pretty much like new, except for the badly done "relic" job on the body:
I'm not a fan of the whole relic thing in general - you know, if you want a beat up looking guitar, get a new or used one and play the shit out of it, and in the process become a better guitar player too - but I'm also a believer that whatever you own, you have the right to mess it up. And mess it up is what the original (or second?) owner did, to this poor Epi LP Special.
First, he sprayed red enamel over the original finish, without sanding or putting a primer on first, then applied a black coat on top of the red. After that, all layers of finish were sanded down through to the top veneer wood in a few spots to simulate wear, probably with an orbital sander. The final step in the uglification process was to apply a very tough epoxy-like clear coat over those areas that were sanded through.
Soon after I got this guitar from John, I noticed that small paint chips, red on one side and black on the other, were being left behind wherever I'd lain the Epi down - on the couch, the kitchen table, or the workbench. Since the relic job didn't include a primer or sanding between coats, the new finish was beginning to lift off. One night I absentmindedly started picking away at it with a fingernail, and a whole bunch of paint came quickly off:
At the same time, I grabbed an unused Telecaster pickguard and placed it on the Epiphone body:
Wow and amazing - the Tele bridge plate cutout on the 'guard perfectly fit the P-90 bridge pickup rout, and the neck cutout was only about 1/8" from fitting. The bottom horn was way too big for the smaller Les Paulish body, but still, it's something to think about.
Next day, I set up a couple sawhorses with boards laid on top, and started scraping off the ugly new finish:
Here's a picture taken as soon as the bulk of the relic paint was removed; I kept the two bridge mounting studs screwed in, to keep paint chips out of the stud anchors:
Next step was rubbing it all down with steel wool to get the last paint remnants off, and smooth it all down:
Here are close up shots of two of the fake worn-through spots on the body; note the tough clear coat that resisted scraping:
In the next picture, the top had been steel wooled as much as possible without wearing the original finish down too much. It's hard to see the wood grain of the top veneer layer beneath the semi-transparent black satin finish (possibly called "Worn Ebony"?) in this outdoor shot, but it's a very nicely done, subtly attractive top coat:
The last five pictures are slightly out of sequence - a pickguard was made after the red and black paint was removed, but before the body was steel wooled. You can see the newly drilled pickguard mounting holes if you look closely.
In Part 2, we'll make (or actually, adapt) the new pickguard, and look at a couple other mods that might work with the Epiphone Les Paul Special II. In the meantime, we'll end this installment with another view of the restyled ugly little Epiphone:
A few months before I picked up the well-worn solid state Peavey Pacer that's being converted into a combo tube amplifier, David in Massachusetts had gotten a similar vintage early '80s Peavey guitar amp that needed some repair. In the end his Heritage VTX 2x12 was beyond help, but he was able to salvage the cabinet, speakers, and various circuit components.
Not only was the amp in very good cosmetic shape, it turned out to have a well made and lightweight solid pine cabinet with finger jointed corners. While converting the Heritage cab into an extension speaker cabinet, David sent a few photos, and those were inspiration, and motivation, for my own Peavey conversion project. Here's his notes about the process:
"Alright, about the Peavey - from what I can remember the VTX chassis is nearly the same size as a silverface Twin, and the same goes for the cab - with the only difference being the slight angling back of the baffle. While I was cleaning the Tolex it lifted at the bottom seam and clearly revealed finger jointed construction. Sorry, but I don't have a photo of that. I did take a pic of the interior corner joint where the glue seeped out from in between the fingers.
Anyway, I could tell the wood was pine from the small knots in the side panels (and during drilling). Only the baffle was MDF. I replaced it with 5/8", void free, 11 ply Baltic Birch and framed it with 1-1/2" x 1/4" pine furring strips.
T-nuts with epoxied down mounting bolts, rear speaker mount.
The Fender tilt-back legs are vintage, from a barn sale in Oregon.
New Neutrik locking jack. 12" Cerwin Vega ER124 and 10" Eminence Ragin' Cajun (1st version).
The chrome hardware was cleaned with naval jelly. New stainless steel screws and bolts.
I think that's everything about the cab. I probably invested around $50 into the refurb and half of that was for the plywood. The amp cost me $40 on craigslist but I recouped that by reselling the 2x12 Peavey Scorpion speakers on CL, and covered the project costs by selling the knobs and transformers on eBay. Net cost for the entire project was $0 (or a slight profit)."
Recently I bought an old funky Peavey Pacer from someone who had it on craigslist. Even though the seller was asking less than a couple Jacksons for it, and re-posted it every couple days, it was still unsold after a month. That's not surprising, since he only had these next two photos in the listing:
Although solid state, Pacers have a solid rep for decent tone, as well as being really loud, and that's the way this one was. Right away it was obvious that the Eminence speaker was in good shape; I turned the Pacer up to ear bleeding levels, and the Brit Series didn't flinch. As predicted, the amp's volume soon dropped to less than 1/4 what it had been, but okay, I'm sold. I handed over some cash and took it home.
The picture at the top of this blog post shows the Pacer as it was at that point, and here's a couple more:
Here's the speaker:
Yup, that's an Eminence, and also yup, that's a boo-boo on the cone, repaired with a bit of black goo. Luckily, the hole in the cone, and the goo, don't affect the sound of the speaker at all. However, it took quite a while to clean the Brit up, in fact, the whole amp was pretty cruddy.
As a double check, the Pacer's amp was bypassed, and the Carvin British hooked directly up to a known good tube amp here, and it sounded very very good - efficient, balanced across the tonal spectrum of an electric guitar, able to handle a lot of power without becoming overly compressed, yet with just the right amount of breakup at higher volume or on dynamic peaks when you're really digging into the strings - nice.
And why is the speaker called a "British Series"? Good question; maybe Carvin was trying to capitalize on the tonal reputation that the older English made Celestions had. But this doesn't sound anything like a Celestion, but rather, just like what it is - one of the better models from Eminence, and in many ways superior for most styles of music than any Celestion. If I had to compare it to any other speaker I've ever played through, the Carvin Brit's tone and efficiency is very similar to that of a late '60s Jensen C12N.
I wasn't going to repair the Pacer; just happy to get a nice toneful speaker, which I was planning to put into a Leslie cabinet. However, the speaker output plug looked a bit suspicious:
I should have taken a photo of the inside of that plug - it was a mess, and the resistance between the plug tip and the the other end of the wire was over 120 ohms. Whoa - maybe that might have something to do with this Pacer's "issues", as the seller called it. I clipped the plug off, and soldered on a new old stock Switchcraft right angle plug:
My hypothesis is (could be wrong, I'm not a solid state repairman) that the incredibly high load on the pair of output devices, 1,500% of rated value, caused them to run so hot that the thermal sensor on the chassis, located between the two big TO-3 sized transistors, went into protect mode, and lowered the circuit voltages enough to save everything from going up in smoke. When the transistors cooled down after shutting the amp off, the sensor would allow the amplifier to run at full power again, until it overheated and go into fail safe mode once more. The Pacer's designers knew what they were doing, and that's great.
Here's a picture of the innards - note the thermal sensor sitting between the two output devices, which use the amp chassis as a heat sink:
As long as I had the amp torn apart, I cleaned it up as well as possible, got a new plug for the AC cable, and since one of the control knobs was missing, a set of old-school radio knobs were put on:
That amp was filthy, but now it's all cleaned up and ready to take to a jam, which I did. I thought the Pacer sounded okay enough for a $20 amp, but wow - I sure wasn't prepared for all the rave reviews it got. Here's a couple examples: "Your new amp sounds horrible!" "That's the loudest piece of sh*t I ever heard!", and my favorite: "I never thought I'd say this, but suddenly your tone really sucks!"
Well okay, the people have spoken. But the Pacer isn't really a crappy amp, it's just me not knowing how to use it. I've played exclusively through tube amplifiers for so long, maybe I've become overly dependent on the natural compression and singing sustain that comes with glowing hot vacuum bottles in a cranked tube amp. But whatever, they were right: suddenly, my tone really did suck.
As a reality check, over the next week I played through the Pacer at home for hours, and it sounded not great but good enough. The problem was that in a band situation, I didn't sound good playing through it. At the next jam, I used a Fender Blues Junior, and all was good again. Oh well, I ended up with a great sounding speaker, and that's why I bought the amp in the first place.
* * *
A friend, David in Mass, hipped me onto the fact that some of the Peavey amps of this vintage had finger or dovetail jointed solid pine cabinets, and suggested I take a look at the Pacer's cab. Sure enough, it's a quality made, lightweight pine cab, although the baffle is a heavy piece of low-grade particle board. As a bonus, the amp chassis seems very suitable for a tube amp conversion build, so my course was clear: I decided to turn the Pacer into a home brew tube amplifier.
After a tear down, all of the Pacer's components besides the baffle, cabinet, and chassis, were sold on eBay for what the buyer, a Peavey aficionado and experienced repair guy, considered a fair and low price for a working circuit board and misc useful parts:
Minus listing and sales fees, and PayPal's transaction charge, I was able to net a bit more than what I'd paid for the amp, and the aluminum trimmed baffle board was given to a neighbor who thought it would look cool as a decoration in his music room:
At this point, I've ended up with a fine sounding speaker, as well as a usable amp chassis and a well made combo cab (minus baffle), for a total cash outlay of less than zero. My kind of no buck/low buck project, for sure.
* * *
In Part 2, we'll make a new baffle from a piece of 60+ year old solid core plywood, and start laying out the chassis for a tube amp conversion. In the meantime, here's a photo in process:
This is a Guild M-65 3/4, made in 1962 in Hoboken, New Jersey. The "3/4" indicates that its 23.0" scale length is shorter than the usual Guild M-65 model, which had a 24.75" scale. At first glance, this hollow body guitar appears to be a normal sized jazz box, but it's actually a very petite little thing. The body is only barely larger than that of a Gibson Les Paul, and if it had the longer 24.75" neck, it would look very Les Paulish, only hollow instead of solid wood.
At 23.0", the scale length is an inch shorter than a Fender Mustang or Jaguar's 24.0", and it's a gas to play, really effortless chordal comping, arpeggios, and single note stuff. The original pickup was made by Franz (or Fransch?) in Queens, NY, and appears superficially similar to a Gibson P90, but a closer look shows that it's not. A perfect tonal match for the beautifully finished laminate arch top body, this pickup has its own unique sound, sharper and clearer than the usual mellower tone coming out of most F-hole bodied electrics. In the middle of a dense jam situation, this Guild really holds its own, and its well defined tone cuts through the mix very well.
It has what looks like a regular Tune-a-matic bridge. Whether that was stock with this guitar, or is an add on, is unknown, but it was already on it when this M-65 was acquired by its present owner in the mid 1980s. The short string length makes it a bit hard to find a string set with just the right tension. After a few tries, I settled on gauges similar to an acoustic light gauge set, only in a nickel wound rather than bronze/brass, and with an unwound third: .012, .015, .019, .032, .042, .052. I used to have a 22.5" scale Fender Duo-Sonic, and those were the gauges of strings I used on the Duo, but I'd forgotten that, until I was reminded.
I should take more photos of this sweet guitar, but - it's not mine. On loan from a dear close friend, it's currently lending some nice tones to a recording project I'm working on. As much as I like it, I know I'm going to have to give it back eventually; however, the more I play this Guild, the more I think I'll just keep it. Just kidding! But, as the title of this post says, it's my new favorite old guitar.
A lot of players like the Peavey Classic 30 tube amplifier, and for good reasons; it looks cool and vintagey, an amazing amount of sound comes out of a fairly compact package, and its bang for the buck is hard to beat.
Before we start getting into the Classic 30's issues, let's list some of its positives:
• The C-30's clean tones are for the most part very usable, and with the internal overdrive switched off, the amp is very pedal friendly.
• Unlike most other modern amps with built-in variable overdrive capability (usually given the misnomer of "channel switching"), the edge, dirt, and aggression tones on tap in this pint sized portable powerhouse are among the best ever packed into a production amp.
• The EQ section is well engineered and has a wide enough range of tone-shaping to suit most musical styles.
• The spring reverb, although a bit gritty when turned up to max, is still miles better sounding than any digital 'verb emulation.
• The excellent quality stock Peavey-branded Eminence made 12" speaker is toneful and efficient, and makes the most of the available power coming out of the four EL-84 output tubes - in fact, the C-30 is plenty loud enough for most rehearsal and smaller gig situations.
Overall, the Classic 30 is a versatile and affordable audio tone tool for the average budget-minded guitarist. Between its on-board OD/distortion and the very flexible equalization, it's a good fit for almost any guitaristic style or genre - so what's not to like?
The Classic 30 is surprisingly hefty for its size, and one might think that's due to a heavy gauge amp chassis and substantial transformers. But the transformers in this amplifier are fairly petite, and the chassis lightweight. The Eminence speaker, with its large magnet, contributes to the overall weight, but much of the C-30's poundage is due to its cabinet, made of some sort of inexpensive lumber industry by-product material. A particle/osb/whatever cabinet will weigh more than double what a comparable cab made of solid pine or quality plywood will, and the C-30, although small, is a weighty piglet.
On the plus side, the C-30's cabinet does have real chromed steel corners. And although the cab is wrapped in vinyl imitation tweed covering instead of actual woven cloth, it might be (possibly, maybe) more durable than real tweed. Or maybe not.
Hot Naked Tubes
As can be seen above, there's no upper panel on the back of the Classic 30 to protect the tubes. Dumb. The tubes are totally at the mercy of whatever stray objects happen to be near the amp, whether a ballistic drum stick or carelessly placed guitar case, or an inquisitive puppy or toddler. Besides no upper back panel, there also isn't a removable lower panel to facilitate taking out the reverb tank during repairs, which makes servicing all the more awkward, since the 'verb pan is connected via an umbilical directly to the circuit board, with no external jacks.
Audible, Not Very Moddable
The Classic 30, and its companion model the Delta Blues, which shares the same amp chassis, are notoriously difficult to service or mod. On any comparable model of Fender semi-pro level amplifier, such as the Blues Junior or Hot Rod Deluxe, simply removing the back panel gains enough access to do most repairs or circuit modifications. This picture from Fender Forum member bluesky636 also shows the Junior's spring loaded output tube holder, and reverb pan situated for easy servicing:
Not so with the Classic 30 and Delta Blues, with their infamous "folded" circuit board, tightly tucked within a cramped compact chassis (photo courtesy of jpfamps.com):
Here's another photo of the folded circuit board in place (from TDPRI member SDS1):
A Series of Unfortunate Filaments
A potential trouble spot in the C-30 is the series-connected output tube filament heater circuit. Rather than having the traditional and rock stable 6.3VAC parallel heater string, as used on millions of tube amplifiers for almost a century, the Classic 30's series connected heaters have the four EL84 output tube filaments connected in line, with each of the tubes forced to handle the entire current draw on the 24VAC supply. Since an EL84's heater draws a nominal 760mA of current, the four-tube series filament circuit has over 3A of current flowing the string, for a whopping 73 watts of AC power running through each and every output tube filament. This design might have a negative impact on tube life, and may be one cause of tube socket terminals separating from their PC board traces.
The three 12AX7/ECC83 preamp tubes have a similar series-connected heater filament string, on a +36VDC supply. Presumably, this is a cost cutting measure, rather than having a separate 6.3VAC filament tap on the power transformer, like the vast majority of tube amplifiers. In the C-30, one 24VAC tap provides two heater circuits, one AC and another DC, a -14VDC supply for output tube biasing, and -15VDC and -30VDC supplies for the ICs and transistors in the amp, through a power supply sub-circuit of diode rectifiers, dropping resistors, and filter capacitors. The same reliability issues may apply to the preamp heaters, as they do for the output tubes.
Socket Rocket to Russia
While troubleshooting and repairing a nice older Classic 30 that was experiencing problems, I concluded that some of the C-30's tube issues can be avoided by the use of Russian made military spec tubes, which were standard issue on this particular amp when new. Long before state funded online troll factories, cyber attack and hacking facilities, and compromising other nation's elections became Russia's biggest new growth industries, they used to manufacture military equipment, a lot of it. And the vacuum tubes developed there in the 1950s and '60s for use in the electronics installed in their aircraft, ships, and tanks were, and still are, among the most rugged, dependable, and resistant to abuse tubes ever made.
Luckily for guitar players world wide, those Soviet era mil-spec tubes are still being made, and sound pretty good, too. It is a little freaky, though, to be buying stuff from people who have thousands of nuclear tipped missiles pointing at everyone all over the globe, ready to launch at a moment's notice. Talk about high pressure sales tactics. Uh, sure Comrade... I'll buy some tubes from you. Just don't kill me, okay?
Die Another Day
This Peavey Classic 30 exhibited some of the same symptoms mentioned above: it was noisy, didn't sound very good, sometimes stopped working entirely, and at times arcing could be heard, in the form of a sharp snapping noise coming from two of the output tube sockets. As well as having output tube problems, this amp also seemed to go through preamp tubes. It arrived with only two out of three 12AX7, and within a few days one of those went south, as well as one of the two that I'd put in as replacements.
The output quad in this used amp was a mixed bag: a pair of the original 6P14P, and two unmatched JJ El84, the newer one of which tested out on my Precision Instruments tube tester as being almost dead. Not coincidentally, the two tube sockets where arcing occurred were those in which the JJ EL84 were installed. The last time arcing occurred, the amp started smoking, a lot. How much was it smoking? Like a tourist from Idaho doing the Eugene legal weed dispensary tour, that's how much.
Usually, when there's smoke coming out of a tube amp, that's a sign of serious trouble, but maybe, if we're lucky, we won't have to call a Death Cab for Peavey just yet.
A quick Google search turned up a few Classic 30 enthusiasts with home brew or commercial after market tube retainers installed in their amps, and some say those holders cured their output tube problems. Here's one, from cortmgm at audiofanzine.com:
Especially impressive was Jeff McLowry's well thought out Tube Tamer project:
After reading Jeff's detailed blog post, and knowing from experience how well the Fender Blues Junior's tube retainer worked, I decided to give it a try in the Classic 30.
I had some aluminum channel stock on hand, and after a quick trip to the hardware store for rubber pass-through grommets and a couple springs, I fabricated this:
New tube holder in action:
Pretty slick! Looks great, but unfortunately it didn't help fix this amp's problems. After putting the chassis back in the cabinet, plugging into power and firing it up, it had the same symptoms as before. Okay, time to take a deep breath, have a beer, meditate a bit, then grab another brewski and dive back into the amp.
Removing a just-installed amp chassis is bad enough, and going through the extra steps to get the Peavey folded circuit board out of the chassis is just no fun at all. Okay, here it is:
Very surreal piece of abstract art. What holds the three sections of the circuit board together are the actual naked, uninsulated jumpers transmitting signal and voltage between the PC boards. Being mid-tensile steel, those jumpers can only be bent a very few times before they crack and fail.
First, the top 1/3 of the folded board has to be bent down, so the control pot shafts can clear their mounting holes, before the whole assembly can be removed from the chassis. Then, we'll need to carefully bend the boards apart enough to service the circuit, and then re-bend them again closer, to position the pots under the control panel. Finally, the upper board, with jumpers, bends back up into its previous box shape when tightening the potentiometers in place - that's four bends during the course of one repair or mod. After that, there's probably not too much more bending left before the jumpers begin to break, and most likely that's a lot of stress on each of the solder pads where the jumpers attach.
Here's the board opened enough to get at the solder joint side of the tube sockets:
A close inspection reveals the root cause of this C-30's problems:
Let's zoom in:
These aren't just dry or cold solder joints - they're separated, and a few of the terminals show signs of overheated and remelted solder, due no doubt to the arcing we'd heard. I dubbed the solder joint on the right "Vesuvius" - you can see that it had spewed molten solder in a wide area around it, very volcano-like. Also, the melted and cooled solder to the right of the tube socket terminal looks very much like a basaltic magma flow.
With a brand new tip on a 25 watt iron, and some old-school rosin core solder, I re-flowed all of the tube socket terminal solder joints, and also inspected every component lead and trace on each of the boards. Saw no other visible issues on the PC boards, and after scrubbing away the exploded solder-blob lava bombs left over from the output tube sockets arcing, I put it all back together and hoped for the best.
A complete set of new tubes similar to what came with the C-30 when new, Sovtek EL84 outputs and 12AX7WA preamps, were popped in, the stock wire bales clipped over each (I didn't put the home brew tube holder back on), then plugged into AC power and flipped the switch. This time, the amplifier gods were smiling, and the Classic 30 came to life and played and sounded as good, presumably, as new.
If the repair hadn't worked, I would have titled this blog post "Four Issues and a Funeral". In case the C-30 was un-fixable, I thought of gutting the chassis and repurpose the amp with a hard-wired circuit such as a '50s Deluxe, but its heavy particle board cab put me off that idea. The only fitting alternative would have been a decent burial.
* Update: Since the repair, this Classic 30 has withstood over 10 hours of jams and rehearsals, plus a few hours at home too - and I don't treat guitars and amps gently. So, okay!
* * *
Well, enough about issues, problems, and repairs. Although the Peavey Classic 30 isn't rugged or reliable enough for on-the-road gigging or pro studio use, it's still a decent sounding stay at home guitar amp with very good built-in distortion tones. And as long as you don't throw it around too much, or take it on your next world tour (unless you hire your own amp tech), it'll probably keep making toneful music, in a home studio, or with the band in your garage, for a long time to come. Just make sure to use the same sort of rugged Russian-made military spec tubes that the C-30 came with, and save those high-dollar old Mullard and Amperex tubes for your hard wired hand-made boutique beauty or vintage Twin Reverb.
Here's a great looking, nicely beat up older Classic 30 (photo courtesy of rodmillerguitars.com):