Right, so i had been on the hunt for the cheapest way i could get a 1x12" or 2x12" guitar cab for a while now - mainly because i landed a toasted Celestion Greenback for free some months ago, and a recone kit is arguably affordable. Budget being a prime concern, i was compelled to look locally, and a couple weeks ago finally pulled the trigger on this thing.
Nothing to really write home about - all solid-state, allegedly 60W output power, equipped with a Celestion Seventy 80 (G12P-80), the facelifted version retailing for 175e nowadays; the asking price for this used one was a very reasonable 50e (arguably even under the price of just the speaker driver itself).
"But wait - there's more!.."
The day before the seller was to deliver it to my day-job, i get a message that he had a bunch of stuff in the trunk of his car, and some umbrella had managed to poke a hole in the speaker cone, and with that, he himself offered to drop the price to 15e(!!!!!). Well, i'm not one to look a gift horse in the mouth - gimme!
Sadly i seem to have overlooked taking any photos of the damage, but the gap couldn't have been more than an oval of about, say... 15x10mm (5/8"x3/8") or so? And not even a "stab wound", but more like a little flap hinged open. Suffice it to say, a couple of carefully applied drops of Titebond and letting it rest for a day or two cured the issue just fine.
Other than that, nothing mega shocking on the inside - if anything, the transformer might be the more... "exotic"(?) component in there, being an R-core. That, and the actual reverb pan. Oops, spoilers!..
Yeah, not all that much to be seen. The size of the board is dictated mostly by the physical spacing of the numerous potentiometers on the front panel, and the single-sided (thus, cheaper to manufacture) copper laminate, needing to fit more tracks & track widths on the bottom layer alone.
"Topcon" capacitors, though? Not sure about the "top", but you can bet your booty they're a con...
Interestingly enough though, over on the emptier end of the board one can notice the markings "TEC80G". The "G" may well hint at "guitar", while the "80" may refer to an (optimistic level of) output power... But Google image search came up with some interesting rebadges of this - Danville, Legend, Tecamp. Hey, actually what're the odds the latter actually designed this thing?
Power amplifier seems to be an ST Microelectronics TDA7294. Now, whether that's even genuine or not, i'll let you decide (or at least speculate)...
Taking a closer look inside, reveals nothing particularly shocking (no electrocution pun intended) - a couple of TL072's, a few NJM2120's (4558's with an output switch between them), some 2SC945 NPN's, some clipping diodes here and there. A nice surprise is the abundance of film capacitors, the cheaper ceramics being used only sparingly, where film cap values are more scarce (sub-1nF). I seriously doubt i'll ever bother reverse-engineering the preamp - i don't think i'll ever muster up the patience to remove & reinstall all the potentiometer knobs, collar-nuts and washers, in order to gain access to the underside of the circuit board. Not unless this blows up, but even then, i'm not sure i'll have much motivation to do that. I do, though, appreciate them labeling all the signals that all the wire-jumpers carry - you don't see that every day.
This thing does actually have a legit reverb pan inside - was it really cheaper than faking it with a PT2399 or some other low-end digital doohickey? Not like it needs to be uber-"hi-fi" anyway.The springs look to have different turn densities... And it's not even Chinese, Belton seem to actually hail from South Korea.
But in all honesty, i have yet to even connect the mains and power up this thing, at all! Priorities, am i right?
Since i intended this to be used as "just" a guitar cab (at least as an option), i needed to gain access to a direct connection to the speaker terminals. But i also wanted to keep the flexibility / option of using this whole thing as it was intended from the get-go, so... Installing a switching jack it is.
Connected the in-contact-with-the-plug-when-inserted contacts to the wires going straight to the speaker, and added a pair of wires from the other side of the normally-closed switches, to where the speaker was connected as stock. That way, with a jack plug inserted into the newly-installed "speaker in" connector, the speaker is completely floating and isolated from the internal circuitry, as well as earth (if mains cable is connected). And since it's all solid-state, there's far less risk of any speaker-is-disconnected-damage, than if it was a tube power amplifier.
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