Modified Leach Super Amp

[mura]

Modified Leach Super Amp






110 V rails,Choke Regulated , Dual Mono with 2 X 1KVA transformers,

Output stage MJ21195 and MJ21196 8 pairs per channel.

Driver stage MJE15034 NPN,MJE15035 PNP.

During initial testing with a speaker during a loud musical peak i saw an input current draw of 6 Amps.Is this OK?

[AndrewT]

Hi,
could you post details of your choke regulated PSU.
Some design calculations to go with it would be nice.
There were a couple of threads recently that could not be fully answered due to lack of knowledge.

Re your output current.
6A into 8R is only 48V. You have about 100V available as drive voltage so output currents approachung 12A into 8R are possible and your stages should be designed to cope with this.
However 8ohm speakers can have impedance dips to below 6ohms in parts of the frequency range (mostly in bass) then your peak current could exceed 17A.

Were you talking about output current or PSU current before the choke?
If before the choke then 6A in and 17A out proves that the choke regulation is working and using stored magnetic energy.

[djk]

I would assume 6A input current is at 240V, about 1.5KVA.

This would be about right for this amp driving an 8 ohm load per channel on music. If it is a choke input filter (as opposed to a Pi filter) I would expect the output to be about 600W at 8 ohms per channel.

[Tony]

good job!

interested on the heatsinks, are they local made? how much do they cost? and can you post links to manufacturer?
thanks....

tony

[jacco vermeulen]

Impressive, Mura.
Any particular reason for choosing MJE15034/15035 as drivers ?

[sajti]

Originally posted by jacco vermeulen
Impressive, Mura.
Any particular reason for choosing MJE15034/15035 as drivers ?

Maybe the better SOA... As I remeber the 34/35 has higher Vce (350V), as the 32/33.

sajti

[jacco vermeulen]

Originally posted by sajti
Maybe the better SOA...

Wrong answer, you should read a datasheet first.

[amplifierguru]

I hate to seem pedantic about detail, but a finned heatsink actually functions FAR more efficiently when mounted vertically and in heights of around 125-150mm. Also the heat draw from your mounted devices is optimised when they are mounted centrally on the heatsink. Why waste value. If only for resource/environment/future generations/... reasons.

It's probably because I'm a physicist, it's entrenched.

Greg

[jacco vermeulen]

Mr Ball,

i suppose this is just a test setup.
Notice the attention to detail, the number of devices that have their legs sleeved.
If not, this is the best arrangement for stewing components and boards.

[mura]

Originally posted by jacco vermeulen
Mr Ball,

i suppose this is just a test setup.
Notice the attention to detail, the number of devices that have their legs sleeved.
If not, this is the best arrangement for stewing components and boards.

Yes it is a test setup. I wanted to make sure everything works before i install it in my monoblock Aluminium Case.

I also got new PCB with integrated support for 8 pairs of TO-247 output devices.

I plan to do 3 Box setup with 1 PSU, 2 monoblock Amplifiers.