Quote:
Originally Posted by FloridaBoy
The copper V-Caps will be a revelation. Be sure to re-visit your 6V6's after they settle in. Do you have a 5R4GY rectifier?
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No, I don't. That one features 67% higher max plate voltage (750 vs 450 volts) compared to my four preferred rectifiers, plus a higher voltage drop (except for the 80):
5U4-G - 5.0 - 3.0 - 44 - 225 - 450 - octal 5Z3 (274)
5AR4 - 5.0 - 1.9 - 17 - 250 - 450 - low Vdrop 5U4/5Y3
5Z4 - 5.0 - 2.0 - 20 - 125 - 350 - low drop 5Y3
80 - 5.0 - 2.0 - 60 - 125 - 350 - 4pin 5Y3
5R4-G/GY 5.0 - 2.0 - 67 - 250 - 750 - high voltage 5U4
Any technical concerns / risks with it?
Here's a quote from poster wyatt at another forum explaining the effects of these specs in an amp:
"The Vdrop is the voltage drop across the rectifier, those numbers (-17, -20, -44, -60) are over-simplified, the actual Vdrop will depend on the actual incoming AC voltage becing rectified. The 5AR4/GZ34 has the least Vdrop, then the 5Z4, then the 5U4G and finally the 80 (5Y3)."
"A side-effect of the voltage drop is the sag it adds. The more Vdrop, the less efficient the rectifier is, meaning it takes longer to supply the current. This adds Sag. When you pick a note or strike chord, the amp demands more current and the less efficient rectifiers can't supply it right away, so you're note/chord sort of drops in volume before ramping back up again. The more the amp is cranked the prominent the sag."
I adhere to these observations because I have always preferred the sound of low Vdrops in my rig. The goto 274B in my case is an intermediate Vdrop (44) so it's a tradeoff and it sounds great with smaller output tubes. The preferred 5AR4 is ideal with larger (more current demanding) output tubes (6550 / kT-88) and this rectifier limits sag.
"Higher voltages mean more headroom and tighter feel. Because the plate voltage changes, you should check bias after swapping rectifiers."
The last statement may create a problem since our amps are self-biased. Should this be a consideration?