Sound difference between MJ15003 and MJ15022?
Searched high and low but could find the original thread on sound differences between transistors so I put my question in new thread.
I wanted to try out MJ15003 output instead of 2N3055 in my JLH amp. I started to look for those new transistors from local shops but currently they were out of MJ15003 and recommended a MJ15022 as a substitute. Could there be any sound differences between MJ15003 and MJ15022?
The MJ15022 is a "newer" part, higher SOA and slightly more linear, but "newer" is in the sense of parts introduced around 1979 versus earlier in the 70's (I know; I designed a pro amp for the company I was working for in 79 using the MJ15024/25 complements.
The real claim to fame for these devices was fairly high second breakdown capability; at 50V, they're really still 250 watt transistors (SOA 50V, 5A), and even at 80V they're OK with 2A. This was a new benchmark for it's time.
Hfe holds up OK to about 3A, and falls after that. Ft at 3A is about 4 MHz.
These are over 20 year old designs; why not use something a little more contemporary, like the 2SK3281/2SA1302, or On Semi's equivalants? (MJL3281/1302). Like the Toshiba originals, they are extended beta devices, with flat gain out to 7A or beyond (depending on VCE), and a typical Ft of 30 MHz. It's possible to get excellent open loop behavior in the output stage with these transistors without running very high bias currents; 10 kHz THD under 0.01%.
go for mj15003 i used it before the minimum hfe for it is 25 while 15022 is 15 but the ft of 15022 is higher(4mhz) than mj15003 (2mhz). don't use mjl/sa1302 audio trans unless you utilize a miller domination cap as the jlh doesn't need the cap since it was design with low ft devices. comparing 3055 and 15003 for Jlh, the treble is more define bass is better.
Thank you for the advises guys.
Though, at first I thought I will try out those MJ15022 anyway and bought couple of pairs of them form that shop.
Only after purchase I started to scrutinize them closer and what I could tell from their looks, they had all the indications of counterfeit devices. So I brought them back to the shop and required for refund. To my big surprise retailer paid back my money with no questions asked. Also he offered some MJ15024 and MJ15003 to me this time. Unfortunately those looked to be fakes too.
Even if it is a happy end I am still back where I should have started at first place– to by 15003 from more reliable retailer.
Oh well forgot to mention that the shop I told you about gets its parts from Nedis, so all European DIYers - be aware.
Parts from Nedis
Nedis is notorious for its second sourced parts. They are low in price but you get seldom the parts from the original manufacturer. I also got TDA1541R instead of TDA1541AS1 for the same price. That did it; slammed the door!:mad:
Also ordered TDA1545 DIL and got a SMT part.:mad:
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