Class A/B, Solid State rectified, circuit board (i.e. NOT point-to-point) wiring. This amp is available in EL34, 6L6, and EL84 models. Mine is an EL34, with one, 12" Celestion 80w in a closed-back combo with reverb. This amp has two channels that are very simple to use. The clean channel, Ch 1 has individual Vol, Bass, and Treble controls. It shares the Master Vol and the Presence with Ch 2. The crunch channel has individual Bass, Mid, Treble, Vol and Gain. The main controls are all on the front face of the amp. The amp comes with a 3 button footswitch which 1, changes between the two channels, 2 engages/disengages the reverb, and 3 engages/disengages Ch 2's "boost" feature--a nice subtle overdrive which is nice for soloing.
The spring reverb is excellent, but an expensive addition to the amp (add $325). It's British-sounding rather than the Fender "surfy," or Peavey "boingy" reverb. I love a good spring reverb on a combo. Just a touch makes the amp sound big like it's in a ambient room.
The rear panel has an FX loop, (1)8 & (2)16 ohm speaker outputs, and a very nice feature: a separate reverb knob for each channel so you can vary them. There is a two speed fan built into the amp that you can set to low for low to mid-volume playing -- very quiet. And if you're really cranking the amp and pushing the tubes, you can set it to high -- less quiet, but at high voulme, you'll never hear it anyway.
I'm a low-tech guy. I really like simplicity in an amp, and this amp is simple. It doesn't have a ton of bells and whistles, but it's still very flexible. I can get a good volume balance going from clean to crunch. While this amp can easily get extremely loud and sound great, you can also get a good, bedroom-volume tone that won't wake your family or neighbors late at night. I should also mention that when you're plugged in but not playing, this amp is very quiet, even at high volume.
Ch 1's clean settings are very nice, and very clean. Sounds marvelous with a chorus. If you want it to stay clean at volume, keep the Ch 1 volume reasonably low and turn up the Master volume. If you crank the Ch 1 volume and dial in the appropriate tone settings, you get a pretty authentic Marshall Plexi rhythm sound. I couldn't quite get the Plexi lead tone, but hey, you can always switch to Ch 2 for a lead tone.
Ch 2 is the crunch channel, and the heart of the amp. The way it is set up, the "Gain" and "Vol 2" will both distort wonderfully smooth and complex, but they are pretty different in tonal character. With a humbucker, if you crank the Gain knob and turn off the Vol 2, you get a very fat Les Paul type tone (a lower mid-peak). If you reverse it: Gain off, and Vol 2 cranked, the tone is much more like a Flying V than a Paul (a higher mid-peak)--think Michael Schenker. Useful to know! What I typically do is blend the two channels and create my own hybrid sound. I leave Vol 2 around 11 o'clock, and the Gain anywhere between 10 o'clock for vintage and 2 o'clock for more of an "80s metal" (you can also use the footswitch boost to do metal too).
It weighs 85 lbs, which is a LOT for a 1x12 combo. In retrospect, I would have done better buying a head over a combo. That's my fault, not the amp's.
Minor complaint 1: There are no numbers on the knobs or faceplate to indicate the setting. I therefore must use clockface analogies. (i.e. the knob doesn't go from 0-10, it goes from 7 o'clock to 5 o'clock)
Minor complaint 2: When you spend $2K on an amp, it should come with a cover, it doesn't. Instead, I got a very nice, padded, cover for it from Tuki (www.tukicovers.com).
The amp aparently requires a special Bogner-made chord for the effects loop. I never needed one so I never bought one.
It arrived with two minor problems: First the metal switch on the footswitch that changes between channels was working intermittently when I got it. Sometimes (not often) it would stick on one channel and it would take 5 to 10 presses to go back to the other channel. I don't consider this a problem with the amp itself. We're all familiar with these switches--they're the kind used in most footswitches and some stomp boxes. Sean at Bogner said they're the best ones available, but you can still get a bad one. They sent me a whole new footswitch, and I sent the faulty one when I got it. Second problem: While cranking up this amp really loud, I noticed something was making a vibrating sound. On closer inspection, I realized that the four screws that actually mount the amp to the cabinet (visible on the top of the cabinet) were not as tight as they should have been. I tightened these four screws and the vibration stopped. These issues probably occured during shipping and the amp has been fine ever since.
The amp carries a lifetime warranty. Bogner has been conscientious and helpful in my few dealings with them.
For 70s hard rock Zeppelin, Purple, Sabbath, to 80s metal, the amp simply sounds fantastic. Like Bogner's cube cabs, this 1-12 thumps like a 4-12. The Shiva's inherent tone is very "middy," i.e. lots of midrange, more Orange than Marshall. If you've always found your tone a little thin, this is the amp that will thicken it up for you.
I should point out, however, that while this amp has plenty of gain versatility, it is not going to give you Mesa Boogie or modern very high gain type tones. This amp is going to give you a very Brown, smooth distortion, a ton of crunch and sustain, and can provide many of the great Dino tones.