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09-12-2018, 11:52 PM
(This post was last modified: 09-13-2018, 08:00 PM by soundmasterg.
Edit Reason: making the power info a little more clear
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I took a Bogen CHB100, gutted it, added my own circuit to it, and then added power scaling to it. It is the same size as a 5E3 Deluxe but a bit taller and heavier. It has a single 12, is about 50-60 watts, and has a breakup like a Vox in that it is smooth with lots of harmonics and touch responsiveness, but it is thicker sounding than a Vox and gives close to but not quite JCM800 Marshall distortion when up loud. Its very versatile and every guitar I have tried through it sounds good. The power scaling circuit made it so I can use it for any gig, though it did take awhile to dial it in just right. It is PTP and looks pretty messy but it is wired up pretty well given that I stuck with the Bogen layout. If I did it again I would build it with a better layout and probably on a PCB or a turret board at least. Would be easier to work on it!
With 480V B+ before I added power scaling, I would have thought it should have higher power. A 7868 with those voltages should be around 44 watts per pair, but this was only giving me 55 watts with a true RMS meter and four 7868's, though I was measuring that on the scope with the signal completely clean. Since RMS is supposed to be measured with 5% distortion, then it is likely a bit higher power than that 55W since I measured it with no distortion, but I don't think it is close to the theoretical 88 watts that the RCA manual says I should have.
Greg
With 480V B+ before I added power scaling, I would have thought it should have higher power. A 7868 with those voltages should be around 44 watts per pair, but this was only giving me 55 watts with a true RMS meter and four 7868's, though I was measuring that on the scope with the signal completely clean. Since RMS is supposed to be measured with 5% distortion, then it is likely a bit higher power than that 55W since I measured it with no distortion, but I don't think it is close to the theoretical 88 watts that the RCA manual says I should have.
Greg
