Jens Rasmussen Leach clone group buy - Page 149

AndrewT · 22nd August 2012, 01:58 PM

One is twice the other.

Junie · 22nd August 2012, 02:07 PM

supply voltage of -/+75Vdc, is it correct now?

AndrewT · 22nd August 2012, 02:14 PM

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.

Junie · 22nd August 2012, 02:21 PM

So is it safe for 2SC5200 and 2SA1943 to run on that supply voltage? so far my amp not smoking yet, it sounding good.

AndrewT · 22nd August 2012, 02:35 PM

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.

Junie · 22nd August 2012, 02:48 PM

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.

tryonziess · 22nd August 2012, 09:48 PM

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

mj777 · 25th September 2012, 10:18 PM

Hi Tad, do you have any plan to organize a group buy again?

regards,
Marjohn

evette · 25th September 2012, 11:40 PM

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

evette · 25th September 2012, 11:53 PM

Mr. Marjohn,,are you looking for pcb,s for the Leach Amp? Evette

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22nd August 2012, 01:58 PM	#1481
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	One is twice the other.

22nd August 2012, 02:07 PM	#1482
Junie diyAudio Member Join Date: Sep 2010 Location: Dubai, UAE	supply voltage of -/+75Vdc, is it correct now?

22nd August 2012, 02:14 PM	#1483
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	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.

22nd August 2012, 02:21 PM	#1484
Junie diyAudio Member Join Date: Sep 2010 Location: Dubai, UAE	So is it safe for 2SC5200 and 2SA1943 to run on that supply voltage? so far my amp not smoking yet, it sounding good.

22nd August 2012, 02:48 PM	#1486
Junie diyAudio Member Join Date: Sep 2010 Location: Dubai, UAE	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.

22nd August 2012, 09:48 PM	#1487
tryonziess diyAudio Member Join Date: Apr 2007	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

25th September 2012, 10:18 PM	#1488
mj777 diyAudio Member Join Date: Dec 2010 Location: dubai	Hi Tad, do you have any plan to organize a group buy again? regards, Marjohn

25th September 2012, 11:40 PM	#1489
evette diyAudio Member Join Date: Jun 2006	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

25th September 2012, 11:53 PM	#1490
evette diyAudio Member Join Date: Jun 2006	Mr. Marjohn,,are you looking for pcb,s for the Leach Amp? Evette