Wow! 100VDC rails

[whatsnext]

I picked up a not dead Crown XLS602 and while poking around found out what 100VDC feels like. Pretty interesting. All the shock but without that annoying 60Hz hum. Is there a reason most of the DIY stuff seems to use lower rail voltages but most of the pro amps I see use at least 70. Four pairs of MJ15025/MJ15024 per channel and a claimed 1200 into 8 ohm bridged.
John........

[johndiy]

high power = high voltage rails, is that simple

high rails have a more pronounced bass musicly

john

[Leolabs]

What's the rating of the transformer???

[TomWaits]

Voltage is potential, the higher the voltage the higher the potential. However, to get power from that voltage you need to support it and stilt it up with current carrying capabilities. Current is the ability to deliver that voltage into a load.

The trend around here for DIY audio enthusiasts is more output devices and bigger power supplies. I'm speaking in generalizations, of course.

I was just looking at a +-100volt supply in a Phase Linear 700B. Looked nice.

Question, who used (uses) the highest rails in a -+ semiconductor amp output? Must be designs that go into +-120V and beyond?

Cheers,

Shawn.

[clem_o]

Rail voltages like that should be able to do pretty much 500Wrms into 8 ohms per channel... that's a fair amount of power!

Theoretical 2KW bridged - so it's current-starved when running bridged mode. The transformer should be pretty much rated at 1200W... (?)

Cheers

[anatech]

Hi Shawn, Clem,
Just peak under the hood of many Carvers. The high rails may commonly run plus and minus 125 VDC. At these voltages some of the problems you normally see have special high voltage problems added. It can be fun. It may also blast your probe tips into a liquid spray.

A non-Carver amplifier with these supplies would be a scary deal. When a Carver fails, it can usually shut down the supplies fast enough to save the rest of the amp and the speakers. With the way the average amplifier is built, I would expect burned off transistor leads and blasted PC boards. Bye bye speaker as well.

I am convinced Carvers are pushing reasonable limits and expectations. But they did a good job. For me, 80 VDC rails are scary enough.

-Chris

[clem_o]

Hi Chris,

For sure, working with high-voltage requires another level or two of caution and awareness!!

I have a question about how Carver manages to squeeze so much power from their amps, but since it's OT, I'll just ask you via PM...

Cheers!

Clem

[TomWaits]

Originally posted by anatech
For me, 80 VDC rails are scary enough. -Chris

Plus/minus 100 volts DC has got to require some serious circuitry? In terms of voltage supply where do we cross over from consumer into commercial? Is there a common threshold?

John, what are you using your Crown XLS602 for?

Shawn.

[whatsnext]

Originally posted by TomWaits


Plus/minus 100 volts DC has got to require some serious circuitry? In terms of voltage supply where do we cross over from consumer into commercial? Is there a common threshold?

John, what are you using your Crown XLS602 for?

Shawn.

Nothing yet. I just got it because the previous owner thought it was dead and I was going to part it out. Turns out it's fine. They probably had shorted speakers or cables that caused one of the many layers of protection to kick in. Either that or their techs are not very techy. I'm sure it would make a kick butt sub amp. The tranny is huge. It makes my 500VA torroids look like toys, probably 20lb. It says 74-0-74 and 18.3-0-18.3 but no amperage ratings. Only 10,000uF of caps per side but the PCB of the PS has room for twice that and the fans are variable speed and are almost silent at idle. Until I build a sub I have nothing that would give this amp the slightest workout. A houseful of speakers I could drive with a SET and a 1Kw amp. Cool.
John......

[Arius]

90V to 100V rails will give about 300W-400W into 8 ohms (accounting for rail droop and output stage losses). Multiply that by (up to) 4 if you bridge it. Many pro amps have such a nice big figure but note that their power supply transformer is about 1.4KVA so you'll never really get more than that amount of power continuous into low impedance loads.

A totem-pole type amp design can easily handle such high rails (e.g. Leach Superamp, Sloan Totem-Pole Optimos). Many of the big monoblocks reviewed by Stereophile are usually stereo bridged amps (vendors prefer to call them "balanced" amps). The high power stereo amps (e.g. Simaudio W-8) use totem-pole.