MPSU 57 / 07 headsup

[Clipped]

for anyone looking for MPSU 07/57 substitutes other than Central Semi, i ran into a cross with philips semiconductor....the actual cross is ECG188/189 ...BUT.. a better match seems to be
ECG 49/50.

ECG 188/189

CBO 80
CEO 80
HFE TYP 80
mhz ft 50

ECG 49/50

CBO 125
CEO 100
HFE TYP 100
mhz ft 150

legs are the same EBC

[1moreamp]

My hats off to you Sir.....
I am bookmarking your post for future needs if I ever run out, heaven forbid that ever happening...Thanks again!

[ECM]

Good looking out Clipped.

I have that 250hcca I need to fix. Hopefully the 07/57 are good, but you never know.

[Perry Babin]

If you use a faster driver transistor, you need to check the output to see if oscillation is a problem. You should run through a range of loads (speaker and dummy loads with series cap, 0.1uf cap across speaker leads, dummy loads with no capacitance as well as a variety of speaker loads) to determine if the amplifier is going to be stable.


In the older Orion amps, doing something as simple as replacing the old output with new outputs can cause low level oscillation. I tried 'faster' outputs (D44VH10 and D45VH10 - specs very similar to the originals) and it oscillated rail to rail.


Has anyone had trouble with the Central semi components? In every amp that I've seen with the Central parts, at least one of the Central components had failed.

[Clipped]

i use BD909/910 or 911/912 for the outputs... i havent ran into any problems using them, but this is just what i can tell by ear.

for the MPSU replacements, im still using transistors like the BD's as pre drive and drivers with the legs bent around to accomodate EBC, and ive been pounding on this amp, and they are still holding up.

on that 2150sx you helped me fix ive changed the pre/driver to BD, outputs to BD, ps fets to 3205, opamps to TI....and it is louder than the other 3 sx's i have... this is just a little annoying, because now i have to make the other 3 just as loud.

ive changed the tantulums to 25 volt also, with hope that the ps will hold up under 16 volts for competition this season.

btw, the original smp60n06....crosses with ssp60n06 labeled as fairchild, but i think samsung makes them....this fet is also labeled as being 'monitor application specific', as you can see by the triangle on the original smp....but i think the 3205 may be better.

[EnvisionAudio]

What's wrong with using the good old 2N6488/6491? No reason to keep using the really ancient stuff.

[Clipped]

cant get the 2n6488/91 in my part of the world... im runnig out of shops to get BD's, every shop i go to...i end up clearing out there stock....20 transistors and 18 fets, orions aint cheap man...

just wondering,...would a darlington work? theyre EBC (BDW93/94).

[EnvisionAudio]

Originally posted by Clipped

just wondering,...would a darlington work? theyre EBC (BDW93/94). [/B]

No, absolutely not. At best you will waste your money. At worst, you will cause more damage.

[Clipped]

no no i meant for the predrive/drive circuit (MPSU) should have been clearer sorry... ehhh come to think of it i would probably still waste money... but i have a couple here staring at me though.

i hate bending the legs for the drive circuit.