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Old 22nd August 2012, 02:58 PM   #1481
AndrewT is offline AndrewT  Scotland
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One is twice the other.
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Old 22nd August 2012, 03:07 PM   #1482
Junie is offline Junie  Philippines
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supply voltage of -/+75Vdc, is it correct now?
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Old 22nd August 2012, 03:14 PM   #1483
AndrewT is offline AndrewT  Scotland
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then 73Vdc rail to rail was stating only half the voltage on your amplifier.
-/+75vDC, +-75Vdc & 73Vdc-0 -73Vdc are quite clear/unambiguous, all three work.

It was the "rail to rail" that caused the confusion.
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Old 22nd August 2012, 03:21 PM   #1484
Junie is offline Junie  Philippines
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So is it safe for 2SC5200 and 2SA1943 to run on that supply voltage? so far my amp not smoking yet, it sounding good.
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Old 22nd August 2012, 03:35 PM   #1485
AndrewT is offline AndrewT  Scotland
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You need to look at the temperature de-rated SOAR for a capacitive/inductive loading.
post1471 said
Quote:
But have you looked at and evaluated the HV SOA of these devices?
It seems that your method is "does it smoke?"
If you have lot's of money, then this is a good method, better than all the simulations can ever predict.
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Old 22nd August 2012, 03:48 PM   #1486
Junie is offline Junie  Philippines
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I don't have money, that's the reason why I'm using the said device because it's cheaper than the suggested one.

I'm not an engineer AndrewT but I can build an amp.
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Old 22nd August 2012, 10:48 PM   #1487
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Junie,
If you already have the boards and are willing to build a very
ROBUST power supply please buy On Semi or equivalent output devices. This design if properly built will last several DECADES. This is one of the most important places to spend money. The outputs do a lot of work and get hot if driven hard. Also, use a very good insulator under the transistor. Heat transfer is imperative. It will only hurt once in the initial buy.

Most of my ten output amps are running 75 to 85 volt rails. They never get hot. I have the bias set at 1 amp per rail with the fuse removed and my meter across the gap as discussed in the Marshall Leach website. Others use different methods to achieve bias, I chose to use this method. As I dialed up the bias the bass just came alive. I use a small screwdriver with a long wooden handle taped to it to keep me out of the live stuff when adjusting the pot. I also was careful to flow the solder to both sides of the board. Some of the devices have contact on the front/back and others on both sides. The frontend is very congested. Layout your build so you can solder the components without too much stress.

Tad
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Old 25th September 2012, 11:18 PM   #1488
mj777 is offline mj777  Philippines
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Hi Tad, do you have any plan to organize a group buy again?

regards,
Marjohn
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Old 26th September 2012, 12:40 AM   #1489
evette is offline evette  Canada
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Mr. Junie What Mr. Tryonziess has stated He,s correct. This is a great amp, and if you need some extra trannies just let me know. Evette
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Old 26th September 2012, 12:53 AM   #1490
evette is offline evette  Canada
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Mr. Marjohn,,are you looking for pcb,s for the Leach Amp? Evette
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