Bogner Shiva suprises

[Bob-I]

I had the opportunity to open and look over a Bogner Shiva this past weekend, some interesting observations.

#1) this amp ROCKS. With some tweaks it sounded very close to my Dumble clone, a tab more spongy but the general charactor was very similar.

The preamp tubes (stock) were mostly Sovtek 12AX7LPS, with one China 12AX7B and one unlabeled in the PI. Power tubes Winged C.

Reverb, superb on this amp, is tube a driver and IC recovery.

Caps are 715, Xicon (blue metal) and WMA (green). Pots were all Alpha. Resistors are mostly carbon film, 1 Watt size. Tons of filtering, main filters are 2-270uF/350V totem pole, another 2-200uF for screens and 5 47uF/450V for interstage filtering. There's also several IC's (I suspect voltage regulation) that were unlabeled. Switching is handled by 5 LDR's and 5 relays.

The PCB has all the tubes mountded directly to it so no lead dress issues.

Next step, go the pics and try to make heads or tails of the architecture. Sorry, can't share the pics out of respect for my friend.

[drz400]

#1) this amp ROCKS. With some tweaks it sounded very close to my Dumble clone, a tab more spongy but the general charactor was very similar.
.

Wow I actually have the opposite experience, a new one with no reverb, got this one cause most say it was the better sounding one. Brand new
I took it apart to see why I DIDNT care for it
Coupling caps in the first 2 stages were small, gotta go back to my notes but like .0022 or .0047, made the channel 2 weak sounding. I thought channel 2 was harsh sounding and not enough girth.
Clean channel shares same first stage as lead channel which has a small cathode cap, making the clean channel kind of weak sounding, I didnt see anything unlabeled, I think there is an IC for reverb but mine had none, The return stage of the effects loop on the instrument return is boosted with an op-amp, two wasted gain stages (not used) could have been used to fix the clean channel and use a tube gain return for the loop. Pots in this one were CTS, some 715P's that really didnt fit, doesnt look like parts are consistant from amp to amp. I could tweak the amp to a place where I like it but there are other amps I like a lot better. No numbers, graphics look unfinished, no fan and gets hot. Only interesting thing is he used a Switching power supply for all the heaters. Drag is that the amp gets very hot and the efficiency of the power supply goes to shit after about 120F it is 5A but he is even running the power tubes and all the switching from this supply which can be had from Digikey for $25. I dont know, I might tweak it or just loose it. As it is kind of sounds lifeless to me