2n3055 vs MJ15003 any recent opinions?

[xjbear]

I can get pretty well matched MJ15003 from Peavey very reasonably priced and also the newer manufactured 2n3055 from mouser or CE.
Any thoughts on these in Acoustic and Peavey amps?

[Enzo]

AMps are remarkably flexible about transistors, so we can usually put an MJ15003 in place of 2N3055 with no problem. But the MJ15003 is a 20 amp part rated at 140v. The 2N3055 is a 15 amp part rated at 60v, though some may carry a higher voltage rating or at least be selected for it. So you cannot put 2N3055 in place of MJ15003 in most places.

Other than maybe some REALLY old first designs, I don;t recall 2N3055s in Peavey amps. I know they used them early on, but I don;t recall in what. MJ15003 was the workhorse of PV amp for a long time.

MJ15003 is my go to part for something like an old Acoustic. But it is important not to mix them. Do not put one MJ15003 in a row of 2N3055. They will not share current well. So all of one or all of the other.

[J M Fahey]

MJ15003 .

You will not get 70's vintage 2N3055H which was the premium version better manufacturers used and modern 2N3055 (E) are no match for them.

I had to stop using 2N3055 around 2003/2004 when my supply run out.
I had been using them since 1969 !!!!!!!!!!

[drewl]

Yeah, some guy named Enso or Enshow or something taught me tat years ago.
The MJ15003 is a good modern day replacement for the old 3055's.

I have couple customers who are bandmates that just kill their old Sunn Concert Leads, running them flat out often into weird impedances mixing different cabs.

By beefing up their amps and using the MJ's the amps can stand the abuse.

[Enzo]

I heard of that guy, I don;t trust him...

[DrGonz78]

I heard of that guy, I don;t trust him...

Except that he makes #1 brand chili.

[J M Fahey]

600V +V 8 x KT88 chili:

[R.G.]

2N3055 in all flavors is only specified to 60V for BVceo. Their safe operating area is quite small by modern standards. I would never use a 2N3055 when things like the MJ15003 and its bigger brothers are available for about the same price. And as noted, if you replace one, replace them all.

[nashvillebill]

Would the MJ15003 suffice as the modern replacement for the 2N3772 (Peavey's in-house number 60142) ?

[Enzo]

The Peavey part order number for MJ15003 is 84140. (Well, really 70484140)

The Peavey part order number for 2N3772/60142 is 84140.

So Peavey seems to think so.

[nashvillebill]

Ah, thanks, I went through their cross reference list but didn't go backwards through the 84140 number. (I actually don't need them at the moment, it was just a matter of curiosity since I've got an ancient amp that uses them)

[Enzo]

I think if I just kept a draw full of MJ15024 and MJ15025, I would have my TO3 needs covered for most anything except the darlingtons.

[xjbear]

Cool which ones would you use then in an acoustic or peavey the mj15024 or 25? Ive got a nasty collection of peavey and acoustic heads from the 70's and a couple Sunn Coliseums

[nashvillebill]

Cool which ones would you use then in an acoustic or peavey the mj15024 or 25? Ive got a nasty collection of peavey and acoustic heads from the 70's and a couple Sunn Coliseums

Well, if I understand your question right: the MJ15024 are NPN so you use them where an NPN was used, and the MJ15025 is PNP so you have to use it where a PNP was used.

[mhuss]

As long as you get good MJs from reputable sources. There was a rash of crappy counterfeit (way) under-spec transistors on the market a few years ago.