superamp with +127 0 -127

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
"can I use leach superamp with +127 0 -127 volts for getting more power at 8 and 4 ohms.like only increasing the r13-14 and 82 ohm pairs."

Essentially correct.

Q5 and Q6 would need to be changed to 2N540X and 2N550X types. Q16 and Q17 will have to go to a different part too, and lots, and lots, and lots more (high voltage) outputs.

Far better would be to build the Super Leach.

http://users.ece.gatech.edu/~mleach/superamp/

Similar changes will need to be made here too, but the series connection really reduces the SOA burden on the drivers and outputs.

What you really should do is order a service manual for a Crest 8000, one of the best pro sound amps that has been around for a long time. The schematic looks just like the Super Leach with some extras, inrush current limiting, relay and DC sense, things of that nature.

http://www.crestaudio.com/products/proseries/pro8001.cfm

ACDs idea has merit too. My Leach amplifiers run on ±63V and do 600W/8R bridged. I have three pair of MJ15011/12 for outputs, for a new build I would use the MJ21193/94.
 
I'm just curious :

What speakers are you planing to drive?

Most drivers [even the big ones with 4" or 5" voice coils] start to 'sweat' when driven with 600W just before clipping and in my experience 1200W is the practical limit for 18" or 21" drivers

To get 1200W into 8 ohms +-150V rails would be required but with so high rails also class G or H operation [ie: +-50V +-100V +-150V] is required in order to mantain dissipation and power consumption in reasonable numbers and to keep under control the costs and the number of output devices required [look for QSC schematics, 'EX4000' model may be a reference]

In my oppinion, if you want more SPL and have reached 500W, the best solution is not to add more power but to add more drivers and more amplifier channels. Increasing the number of drivers also increases efficiency so theoretically dual drivers with 500W + 500W produce as much SPL as a single driver with 2000W

Proper horn loading may also boost the SPL by 10dB, and this is a serious thing since it means that 100W of input in a horn loaded system may produce as much SPL as 1000W of input in a direct radiating system

If you want to produce some SPL outdoors, the absolute minimum number of bass drivers or bass horns to place toghether is four [mono bass or four at each side] due to spatial loading issues. Groups of less units will suffer from very poor efficiency
 
"I'm interested in your leach bridge. can you share me your
bridge phase inverter schematic & pcb.?"

That pair were actual LSR&D 101 that were offered in kit form. A shake-the-box kit only requiring a screwdriver to complete.

http://sound.westhost.com/p20_fig1.gif

This method of bridging is not the best in theory, but it has less problems in practice. The Adcom GFA555 uses this method.

http://patft.uspto.gov/netacgi/nph-...&f=G&l=50&d=PALL&RefSrch=yes&Query=PN/3772606

Original class H method, easily adapted to the Super Leach.

http://patft.uspto.gov/netacgi/nph-...,387,876.WKU.&OS=PN/5,387,876&RS=PN/5,387,876

Shows both the Crest class H method and the QSC grounded method

http://www.uspto.gov/patft/help/images.htm
 
i do not have it in elctronic form yet, it can be found in the audio magazine issue dated february 1975, page 28...

the basic principle is to connect a resistor eqaul to the feedback resistor from output of driving channel to the inverting input of the driven channel,this makes the gain of the driven channel equal to unity, the non-inverting input of the driven channel is effectively grounded, input is fed to the non-inverting input of the driving channel...speakers are then connected to the outputs of both channels...

the slide switch is used to get this condition in a bridge mode...

hope i explained this clearly...

tony
 
Bridge is the best idea,but...

If different, and always some differences in amplifier channels, you will have different half cicles problems. They interact, but not correcting differences, they create a third circunstance.

Have to do it more precise, if not, result will be power without quality. You can see, never two channels completely equal, very rare, more exception than the usual results.

When people say, bridged them!, they are saying "Bridge two perfects, and exactly the same amplifiers"....this is not easy to do.

I tried too, but used 122 volts....had a burned amplifier, not Leach!, another one!, it could not stay alive, i was using the 250 Volts transistors too.....maybe with 110, or 100 can survive if you separate power voltage from input voltage, and keept low using regulator with Zener.... More voltage in the first stages resulted in more driver voltage, and a little lower voltage in output can be "healthy" to output transistors, but remember that voltage are always reduced when you push amplifier hard, this final voltage may be considered as real working voltage.

I think is a very good idea, and results can be good to all of us, beeing sucessfull or not. Of course, no doubts, for you a $ risk, and easy to me to say, do it!, because nothing will happens with my own bank account... Edson, and many others, pay a big amount of money researching their ideas. I am paying too, but first i simulate in those, not entirely confidence spicers, but they are saving some money.

Real world example, the Titanic my friend Hurricane made.... 104 volts!.... no problem!....but voltage goes to 63 when hard driven.... this way was safe.... if stable in 104..... do not know if can survive too long.

If you move in the direction of "try some", please, keep me informed:

nanabrother@yahoo.com

regards,

Carlos
 
Leach Amp at +/- 100V

Hai All,

I've got a double barreled super amp running as a main amp. The power supply I use delivers +/- 100 V.

The reason I've started to build this amp with this power supply was that I had the power supply lying around.

Actually I blew up my previous amp (Proton D1200). This amp has a power supply running +/- 110 V. In order to get the output voltage back to 100V, I've used the 12 Volt output of the transformer as my ground.

Never felt really save when building and testing this amp. When someone plans to build an amp with a power supply like this. Use a variac when testing.

Michael
 
"the basic principle is to connect a resistor eqaul to the feedback resistor from output of driving channel to the inverting input of the driven channel,this makes the gain of the driven channel equal to unity, the non-inverting input of the driven channel is effectively grounded, input is fed to the non-inverting input of the driving channel...speakers are then connected to the outputs of both channels..."

http://sound.westhost.com/p20_fig1.gif

"Actually I blew up my previous amp (Proton D1200). This amp has a power supply running +/- 110 V. In order to get the output voltage back to 100V, I've used the 12 Volt output of the transformer as my ground."

Is that rated at the same current as the main winding?

I think not.

Use it as is.

The Proton is a class G, you can hook it up to the Super Leach by adding the two diodes shown in the patent and then it will run class H. Or you can just run it stock in AB with bigger sinks.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.