So what powers this beast?

stephie's place

Moderator: sbench

Post Reply
sbench
Posts: 296
Joined: Fri Jan 28, 2005 3:45 pm

So what powers this beast?

Post by sbench »

The intent of this project is a totally "contained" amp. That is, phono preamp, line amp and power amp. In addition, the amplifiers are intended to have no caps in the direct signal path. The power supply becomes important, since it *does* have capacitors. The HV is intended to be regulated and no output side capacitors.

The PA is a totem pole, EL34 driven by D3a. The B+ requirements are 462V regulated at 200mA. There is an intermediate 172 volts at the totem pole center. Since the output stage draws more current than the driver, this 172 volts is "shunt" regulated by zener (actually 2 banks of zeners totalling 172 volts) and this also powers the line stage. The phono is powered from 2 independent 220 volt regulators. The PA also requires 2 independent isolated 250 volt regulators for the screen grids of the EL34s.

In addition, I planned a 3 stage mute/turn on delay, 12 seconds, 40 seconds, 90 seconds.

Here's the overall specifications I designed to...
+520V 250mA (drives 462V regulator)
+360V 250mA (part of same... this part drives 220v regulators)
6.3VDC 1.5A filtered, isolated - filament for line stage maybe
6.3VAC 8A - EL34 heaters
+462V 200mA regulated
+220V 25mA regulated
+220V 25mA regulated (one per channel)
+250V 30mA regulated, isolated
+250V 30mA regulated, isolated
+12.6V/+18V 1.5A regulated. Filament for phono stage. 18v not used.
+15VDC 100mA. Mute Relay(s) B+
Delay1 12 seconds... slow start of +520 and +360V sources.
Delay2 40 seconds, ground after 40 secs for mute relays on line and PA.
Delay3 90 seconds, ground after 90 secs for mute relay on phono stage.
LEDS: 8 as...
+462, +220, one of the +250, +12.6
Mute:Delay1, Delay2, Delay3, Discharge
(when power is remover, the mute relays quickly mute the system before any other power supply "wiggles", and discharge/rearm the delay circuits. This is for power surge, storms etc)

Input: 115 or 230 VAC 50 or 60Hz. 390VA.

Output: DB25 connector (all voltages) DB9 (phono section in case it don't fit)

Attached .PDF files describe...
MAINPS.PDF = System block, transformers, I/O
HVREGS.PDF = 360 and 520 sources. 462V regulator, both 220V regs.
M_PS_OR.PDF = both isolated 250v sources and regs, 18/12.6V source and regs, 6.3VDC filtered source.
PS_DLY.PDF = mute circuitry.

Steve
Attachments
m_ps_or.pdf
(17.66 KiB) Downloaded 792 times
hvregs.pdf
(19.08 KiB) Downloaded 772 times
ps_dly.pdf
(15.22 KiB) Downloaded 744 times
mainps.pdf
(21.78 KiB) Downloaded 810 times
Post Reply