Do these 2N3055s look genuine?

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Aaronrash

Well-known member
Joined
Jan 5, 2012
Messages
244
Location
Houston TX
Hey everybody, I found these vintage motos and had to buy them since they are getting so hard to find. To me they look authentic but I figured I would post some pics and get other opinions who have maybe dealt with this transistor often
 

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gswan said:
Since when was a 2N3055 hard to find? These are jelly-bean parts.

Yeah modern day 2N3055s are very easy to buy practically anywhere, but I am talking about the NOS Motorola 2N3055s used in the original 1073s. They are extremely slow and horrible spec but they are characteristic in vintage sound.

These are so hard to find that they are counterfeited allot and that's why I'm posting this theard to see if they are genuine.

If you can find old motos manufactured in the US from the 60s through 70s that are like jelly bean parts, please point me to where?
 
[IRONY] I think you need to do a gas chromatographic analysis of the paint used for marking, Motorola was well known for the use of cadmium based paint during the seventies so you should be able to clarify the origin of the parts quite easily.... not! [/IRONY]

if they 'feel' like originals, I'm sure they are going to sound like originals too...

- Anonymous, I don't want to be flamed...
 
One difference I noticed right away is how light they are. They hardly weigh anything. I guess the older ones were aluminum while the current day ones are steel. I'm sure they are real.
 
Motorola TO-3 were always steel (kovar?) AFAIK.  I think the first aluminum TO-3s I recall were Hitachi mosfets.

It seems one could tweak the circuit to mimic the low gain bandwidth of early 3055 parts.

JR
 
Aaronrash said:
I guess the older ones were aluminum while the current day ones are steel. I'm sure they are real.

Yes, you are right,  they are real.
The first aluminum TO3 transistors I saw was some TFK from early seventies.
 
Yup they are real i got 11 of them and they look exactly the same as yours.
 
KDE said:
Yup they are real i got 11 of them and they look exactly the same as yours.

Thanks, yeah the guy I bought them from had hundreds of vintage transistors so I doubt they are knockoffs

I want to try these out in my 1073s and see how they sound. I have a generic Mospec 2N3055 in there right now that sounds pretty good. Geoff says they tested the Motorolas for bandwidth in the 1073s witch is something I have no idea how to do without a curve tracer.

I also don't even know what they really mean by bandwidth, frequency response maybe?
I also hear they are very slow, I'm guessing they mean slow in the sense of like a old tube with a slow slew rate?

Can anyone that has used the vintage Motorolas comment on how these sound compared to the generic modern day 2N3055
 
Aaronrash said:
KDE said:
Yup they are real i got 11 of them and they look exactly the same as yours.

Thanks, yeah the guy I bought them from had hundreds of vintage transistors so I doubt they are knockoffs

I want to try these out in my 1073s and see how they sound. I have a generic Mospec 2N3055 in there right now that sounds pretty good. Geoff says they tested the Motorolas for bandwidth in the 1073s witch is something I have no idea how to do without a curve tracer.

I also don't even know what they really mean by bandwidth, frequency response maybe?
I also hear they are very slow, I'm guessing they mean slow in the sense of like a old tube with a slow slew rate?

Can anyone that has used the vintage Motorolas comment on how these sound compared to the generic modern day 2N3055
Probably talking about ft or gain bandwidth. At higher frequency the current amplification capability of the transistor falls off. The 3055 was a rugged workhorse power transistor but not ideal for HF use.

I have nothing to offer about pursuit of legacy "sound". I expect the designer at the time was trying to make the path flat and linear using the parts available at the time. 

JR
 
Crack 'em open, I've seen some pictures of counterfeit transistors (but those were modern types, I believe Motorola ones, used in diy HiFi amps), but these had a much smaller die in there than the originals. You may not want to do this on all your 2n3055's  :)
Where did you buy them? What kinds of other components did the seller have?
If it is obvious the seller has all kinds of old stock (including a lot of stuff that you really can't do anything with, like say, old Dolby B IC's  :-\ ) then they probably are NOS. But if the seller has is pretty anonymous, perhaps some negative feedback (on eBay), only has really sexy components, is a lot cheaper than other vendors etc etc... thread carefully.
 
[quote author=Aaronrash]
Can anyone that has used the vintage Motorolas comment on how these sound compared to the generic modern day 2N3055
[/quote]
seems that despite the advices of james your quest for vintage neve sound is not over
http://groupdiy.com/index.php?topic=54302.msg693906#msg693906
maybe you should  try looking for original Tx...I guess it would make more differences soundwise than changing 3055.

Regarding fake motorolas 3055 you can crack one open and look for the copper heat spreader. Fakes don't have one.
http://sound.westhost.com/fake/fakes-r1.jpg
 

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