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General Discussions => The Lab => Topic started by: Potato Cakes on February 11, 2020, 01:05:14 AM

Title: TO-3P-3 replacements for 2n3055
Post by: Potato Cakes on February 11, 2020, 01:05:14 AM
Hello, everyone,

I am looking to use a TO-3P-3 NPN BJT to replace the infamous 2N3055 in a circuit design. The power specs seem very comparable, but the one thing I wasn't sure about is the bandwidth. The 2n3055 is rated at 200kHz and the lowest for the TO-3P-3 is 3MHz with most of them rated for 30MHz. My concern is that using this higher bandwidth for the output transistor will cause instability. Being that this is in the output section of a preamp stage with a transformer that follows it, how concerned should I be about instability in this application?

Thanks!

Paul
Title: Re: TO-3P-3 replacements for 2n3055
Post by: JohnRoberts on February 11, 2020, 08:57:48 AM
The 2n3055 was a generic popular "go to" npn power device. Modern device processes are much better and new ones will as you have observed have improved gain bandwidth metrics compared to original old soldiers (original 3055 was slow as molasses and hard to kill).

Wider gain bandwidth is not automatically a risk for instability, might behave better with less lag, or not.

If possible try one and see how it behaves. You should be able to increase stability compensation  if needed.

JR

 
Title: Re: TO-3P-3 replacements for 2n3055
Post by: Potato Cakes on February 11, 2020, 12:07:08 PM
Thanks, JR.

I am aware that the 2N3055 is old and slow, but also aware that swapping parts out for higher slew rates/bandwidth might also be an issue, and even more aware that my electronics knowledge is novice at best so I feel the need to double check every "creative" thought I have when changing out parts to suit my desires. Would a zobel network on the output transform suffice as compensation or will that have to be done somewhere else?

Thanks!

Paul
Title: Re: TO-3P-3 replacements for 2n3055
Post by: JohnRoberts on February 11, 2020, 03:48:59 PM
Thanks, JR.

I am aware that the 2N3055 is old and slow, but also aware that swapping parts out for higher slew rates/bandwidth might also be an issue, and even more aware that my electronics knowledge is novice at best so I feel the need to double check every "creative" thought I have when changing out parts to suit my desires. Would a zobel network on the output transform suffice as compensation or will that have to be done somewhere else?

Thanks!

Paul
I can't guess what you will experience.

Note: some aficionados of "old stuff" believe there is something magical about old slow parts. I do not argue with people on the WWW about what they say they hear. 

Instability in a NF circuit can be caused by the combination of more than unity loop gain with more than 180' of phase shift/delay lag in a NF path. When the phase shift/delay causes the negative feedback to appear positive "and" gain is higher than unity, oscillation can happen.

Most active circuits already contain some stability compensation so A) your circuit may not even oscillate, or B) the fix may be as simple as adjusting the value of an existing compensation cap.

BTW authentic old/slow 3055 have not been manufactured for some time now, so I suspect these circuits may already be working out in the wild using modern parts.

JR 
Title: Re: TO-3P-3 replacements for 2n3055
Post by: Potato Cakes on February 11, 2020, 06:56:19 PM
I can't guess what you will experience.

Note: some aficionados of "old stuff" believe there is something magical about old slow parts. I do not argue with people on the WWW about what they say they hear. 

Instability in a NF circuit can be caused by the combination of more than unity loop gain with more than 180' of phase shift/delay lag in a NF path. When the phase shift/delay causes the negative feedback to appear positive "and" gain is higher than unity, oscillation can happen.

Most active circuits already contain some stability compensation so A) your circuit may not even oscillate, or B) the fix may be as simple as adjusting the value of an existing compensation cap.

BTW authentic old/slow 3055 have not been manufactured for some time now, so I suspect these circuits may already be working out in the wild using modern parts.

JR

Ah, yes,  the NOS transistor argument. I did that one time when I was building an ez760 (ADR Compex type compressor/gate) and most of the NOS transistor parts I ordered were either fake or just didn't work, creating a troubleshooting nightmare as the circuit has more than a handful of transistors in a variety of models. After that my eyes were really opened to the silliness of those types of arguments and I started finding modern replacements for those parts. I still have several newer 2n3055's that I bought a couple of years ago, but I know if I am to look at making a board for continued use it's probably not smart to rely on a finite supply of a discontinued part (or soon to be). I've also been using newer parts for the older, coveted circuits I've built and they all sound fantastic. I don't know how they compare to the "real" thing (serial number dependent) but it does cause clients to be severely impressed.

I'll get couple of types and try doing a direct replacement and report back. It will probably be a couple of weeks before I do.

Thanks!

Paul
Title: Re: TO-3P-3 replacements for 2n3055
Post by: Whoops on February 11, 2020, 08:53:06 PM
but I know if I am to look at making a board for continued use it's probably not smart to rely on a finite supply of a discontinued part (or soon to be).

I understand what you say about NOS and not wanting to do develop a project with hard to find parts,
I just don't understand why do want to replace the 2N3055.
Why do you say that the 2N3055 is a soon to be discontinued part?

This transistor is used in so many different devices, it proved to be useful and sturdy  in different applications (ex PSU and Power amplifiers).
I've just checked and farnell alone has 24 thousand units in stock, other suppliers also have high quantities, so I really don't see this transistor being discontinued anytime soon

Farnell aprox 24000 units
Mouser aprox 1700 units
Digikey 4500 units
Title: Re: TO-3P-3 replacements for 2n3055
Post by: Potato Cakes on February 11, 2020, 11:11:54 PM
I understand what you say about NOS and not wanting to do develop a project with hard to find parts,
I just don't understand why do want to replace the 2N3055.
Why do you say that the 2N3055 is a soon to be discontinued part?

This transistor is used in so many different devices, it proved to be useful and sturdy  in different applications (ex PSU and Power amplifiers).
I've just checked and farnell alone has 24 thousand units in stock, other suppliers also have high quantities, so I really don't see this transistor being discontinued anytime soon

Farnell aprox 24000 units
Mouser aprox 1700 units
Digikey 4500 units

Interesting. I was sure not to long ago they were a little harder to find and quite a bit expensive, though if memory serves me correctly they were all TO-3 and the newer ones are TO-204-3, which I don't see a difference unless there is a slight change to the case dimensions.

The other thing to consider is the footprint. The 2n3055 takes up quiet a bit of space and I don't know how crowded the real estate on the PCB I'm working to design will be, but I think anything thing I can do to cut down on the board dimensions will be a bonus.

Since I am not building a PSU nor an amplifier, I think I will still explore swapping out with a newer TO-3P-3 part as it has it does have higher bandwidth. And hopefully I'll learn something in the process. Which is always the goal.

Thanks!

Paul
Title: Re: TO-3P-3 replacements for 2n3055
Post by: Whoops on February 12, 2020, 12:00:20 AM
Interesting. I was sure not to long ago they were a little harder to find and quite a bit expensive, though if memory serves me correctly they were all TO-3 and the newer ones are TO-204-3, which I don't see a difference unless there is a slight change to the case dimensions.

They were always easy to find, the transistor is used in Neve BA283 amplifiers, so a lot of people use them around here when building Neve type circuits and there was never a shortage as far as I can remember

The other thing to consider is the footprint. The 2n3055 takes up quiet a bit of space and I don't know how crowded the real estate on the PCB I'm working to design will be, but I think anything thing I can do to cut down on the board dimensions will be a bonus.

Definitely they take quite a bit of space.
TO-3P take much less.

wish you all good to your project
Title: Re: TO-3P-3 replacements for 2n3055
Post by: Potato Cakes on February 12, 2020, 12:08:13 AM
Thanks! I'll be a while before I get to test this out, but I will report back when I do.

Thanks!

Paul
Title: Re: TO-3P-3 replacements for 2n3055
Post by: CJ on February 12, 2020, 01:25:03 AM
leakage current, that's where the tone lives.  :D

we swap out old school 3055 stuff for MJ21194  all day long in Marantz receivers and i tell you what, the new transistors sound a bit harsh.

not to say that after a little break in period they might mellow out but that is another different can of worms right there.  i don't have time to wait around a year and make a conclusion.

but how long will those low voltage NOS 3055's last? there is a dependibillty (sp) tradeoff there.
Title: Re: TO-3P-3 replacements for 2n3055
Post by: synthiaks on February 12, 2020, 04:28:35 AM
This is interesting as I'm having a suspicion that a 3055 from Tesla is failing in an Old GDR active speaker that I have.

So the facts are:

3055 is still manufactured to better specs but the online argument is that the older "slower" ones sound better?

Or is it more to it than that?

Just to kind of fine tune my snake oil Radar on this discussion. Before I spend nights and days to find 3055s from the 70s :)

S
Title: Re: TO-3P-3 replacements for 2n3055
Post by: CJ on February 12, 2020, 06:55:38 AM
the 3055 topic is by no means new around here, you might find some interesting reading from days gone by,

https://groupdiy.com/index.php?action=search2



hmm, weird, can not seem to link to a page full of 3055 threads, anywho, if you type 2N3055 in the search box at the star above, you will be greeted by a virtual smorgasboard of info.
Title: Re: TO-3P-3 replacements for 2n3055
Post by: synthiaks on February 12, 2020, 08:34:13 AM
the 3055 topic is by no means new around here, you might find some interesting reading from days gone by,

https://groupdiy.com/index.php?action=search2



hmm, weird, can not seem to link to a page full of 3055 threads, anywho, if you type 2N3055 in the search box at the star above, you will be greeted by a virtual smorgasboard of info.

Sorry...

I got to lazy there :)

As a Swede I'm always looking for a good Smörgåsbord.

S
Title: Re: TO-3P-3 replacements for 2n3055
Post by: JohnRoberts on February 12, 2020, 09:46:04 AM
leakage current, that's where the tone lives.  :D

we swap out old school 3055 stuff for MJ21194  all day long in Marantz receivers and i tell you what, the new transistors sound a bit harsh.

not to say that after a little break in period they might mellow out but that is another different can of worms right there.  i don't have time to wait around a year and make a conclusion.

but how long will those low voltage NOS 3055's last? there is a dependibillty (sp) tradeoff there.
I remain suspicious of unqualified anecdotal sound quality claims like "sounds harsh".  Further I do not expect them to "break in" with time. 

If only you had a test bench so you could back up your observations with numbers.  In my experience I could pretty much measure anything that I could reliably hear, while I could measure things that I could not hear.  :-[

JR
Title: Re: TO-3P-3 replacements for 2n3055
Post by: CJ on February 12, 2020, 03:53:36 PM
well, i'm from Mississippi, the "show" me state.   :D

is there a piece of test equipment that will  measure the beauty of tropical fish in Hawaii?



i like the sound of these silver 4558's, don't know why,  :D

Title: Re: TO-3P-3 replacements for 2n3055
Post by: JohnRoberts on February 12, 2020, 04:53:48 PM
well, i'm from Mississippi, the "show" me state.   :D

is there a piece of test equipment that will  measure the beauty of tropical fish in Hawaii?



i like the sound of these silver 4558's, don't know why,  :D
You are thinking of Missouri....

You can make good soup with ugly bones...

JR
Title: Re: TO-3P-3 replacements for 2n3055
Post by: shabtek on February 12, 2020, 07:34:37 PM
Is this gonna veer into a recipe/cooking discussion?
Loves me some real soup stock, tis hard to find ugly bones at the local grocers: only boneless skinless and “stock” comes in a paper carton.
I do have some old hens roosting so good soup will be on the menu soon.
Title: Re: TO-3P-3 replacements for 2n3055
Post by: JohnRoberts on February 12, 2020, 07:57:35 PM
Is this gonna veer into a recipe/cooking discussion?
Loves me some real soup stock, tis hard to find ugly bones at the local grocers: only boneless skinless and “stock” comes in a paper carton.
I do have some old hens roosting so good soup will be on the menu soon.
Have you ever used bay leaves in soup? (but I was making a metaphor)

JR
Title: Re: TO-3P-3 replacements for 2n3055
Post by: Whoops on February 12, 2020, 09:39:22 PM
3055 is still manufactured to better specs but the online argument is that the older "slower" ones sound better?

Or is it more to it than that?

Just to kind of fine tune my snake oil Radar on this discussion. Before I spend nights and days to find 3055s from the 70s :)

Don't think so, never heard anything about older 3055 sounding better than new ones, never heard anything about a new 3055 not working when replacing and older unit.
I replaced quite a few in the past and always used off the shelf modern replacements, On Semi, Toshiba, ST , all of them work very well.

There might be some discussion on vintage ones because at some point Neve used Motorola branded 2N3055, but thats really just because people see photos of Motorola transistors in Neve BA283 boards, not that they sound any better than others.
Neve actually originally used NewMarket 2N3055, but there's less people looking for those because they appear in less internet pictures.
If someone influential says somewhere online that Newmarket transistors sound better than Motorola's and are crucial to the Neve sound, then some people will trash their Motorola's stock NOS.
Any 2N3055 works well in a Neve type circuit, and also never had any problems in replacing them in power amps.
Never had to replace them in PSUs

This is my experience with 2N3055 from different brands and time periods, if anyone has a different experience please share
Title: Re: TO-3P-3 replacements for 2n3055
Post by: CJ on February 12, 2020, 10:35:39 PM
some people have different hearing than others.
Title: Re: TO-3P-3 replacements for 2n3055
Post by: Whoops on February 13, 2020, 12:19:03 AM
some people have different hearing than others.

I agree,but hearing is not ruled by what the ears capture.
The biggest difference between people it's the Brain itself. It's also the brain that listens and interprets a sound.

The Brain can be influenced by a lot of different things, not only senses like the ears, and it's quite complex.
So yes someone that likes silver gloss, might prefer the sound of a silver component or piece of equipment.

But I was not even arguing that I was giving my honest knowledge based on my experience with the 2N3055,
I'm totally open to other opinions and people with other experiences.

So in your case CJ, is there any specific type of brand of 2N3055 that you prefer and why?
Or did you encounter any problems in replacing an old 2N3055 with a new production one?

Title: Re: TO-3P-3 replacements for 2n3055
Post by: synthiaks on February 13, 2020, 01:49:19 AM




Whoops: thank you for giving such a extensive answer to my lazy question!

The biggest difference between people it's the Brain itself. It's also the brain that listens and interprets a sound.

Working with sound post for Cinema for the last 15 years I can say that's so true. What someone hear can be impossible to hear or even understand for someone else. This is also why I'm a bit sceptical towards the discussion how capacitors "sound" for example.

Then not even considering the fact that many people probably dont even hear that well. Even among the audio pros the elefant in the room is that, experience gained with age, will be hearing lost.
 
Title: Re: TO-3P-3 replacements for 2n3055
Post by: JohnRoberts on February 13, 2020, 12:47:44 PM
There are clearly measurable differences between people's hearing, but +1 to Whoop's observation that there are larger differences in human's post processing (meat computer).

I won't repeat all of my goto anecdotes but one perhaps germane one was the year Peavey introduced their most successful solid state tube mimic (transtube) at the NAMM show with single blind A/B testing in the booth. After several days of random A/B trial results, only 2 or 3 individuals could reliably tell which was glass and which was silicon. This suggests that critical listening is learned or based on life experience. These individuals were experienced guitarists who knew what to listen for (the design engineer could tell them apart also). 

Since human perception is generally flooded with too much information, different people selectively discard different excess information. I suspect there are different areas of specialization. An orchestral conductor will have developed different sonic focus, than guitar players, etc.  I recall working on a SMPTE to midi synchronizer back in the 80s and a bass player who worked with us was driven to distraction by minuscule timing errors in the midi clock driving a drum machine. He had a highly evolved sense of timing, a useful skill for bass players.

I personally find listening tests pretty well worthless for circuit design other than to confirm there are no gross errors.

JR
Title: Re: TO-3P-3 replacements for 2n3055
Post by: CJ on February 14, 2020, 03:05:31 AM
Certain mastering engineers seem to be able to rack up impressive stats on album sales, time after time.

Perhaps they have a gift for music.

If you try out 200 guitars they will all sound a bit different. What do you right down on the spec sheet as to why they sound different?

After a guitar amp circuit is built, the tweaking stage is next. This is done by trial and error. Different caps, resistors, tubes, transformers, speakers, cabinets. What sells and what does not sell is going to depend on the person doing the tweaking.  Will taking a scope shot or measuring distortion at different frequencies tell you the answer?  Transient response using a square  wave?  No.It is the designer who makes the difference. Not the specs or the circuit.  Why do you think James Brown suffered Eddie Van Halen?  :D
Title: Re: TO-3P-3 replacements for 2n3055
Post by: synthiaks on February 14, 2020, 04:50:10 AM
Certain mastering engineers seem to be able to rack up impressive stats on album sales, time after time.

Perhaps they have a gift for music.

If they are over 45 They probably have an Assistant Making sure everything is OK over 14K :)

I don't argue against designer Tweeking I'm just sceptical towards the fellows that have "listening sessions" with capacitors and pay 300$ for audio cables. ::)

Just swapping an on-amp in a "tweaked" circuit and then hearing things described like " transparent" or "air" makes my alarm go off.

But hey, I'm not a audio electronics professional, I work with cinema sound and have 85dB SPL on my ears day in and out so I probably can't hear "transparent" anymore
Title: Re: TO-3P-3 replacements for 2n3055
Post by: JohnRoberts on February 14, 2020, 11:31:39 AM
Certain mastering engineers seem to be able to rack up impressive stats on album sales, time after time.

Perhaps they have a gift for music.
or a strong awareness of consumer taste and trends.
Quote

If you try out 200 guitars they will all sound a bit different. What do you right down on the spec sheet as to why they sound different?
write? Guitar players don't read spec sheets (at least the vast majority do not), so it doesn't matter.  Then there are a long list of tangible intangibles that affect how a guitar plays and feels only indirectly affecting the sound.
Quote
After a guitar amp circuit is built, the tweaking stage is next. This is done by trial and error. Different caps, resistors, tubes, transformers, speakers, cabinets.
I don't think it is that much left to chance at least not with the professional amp designers I have known. There is quite a lot of iterative tweaking but not totally random. I recall how painful it was when my lab was upstairs directly above the guitar amp engineers and there was a bass amp engineer who couldn't play a lick. :o

Mercifully after several months he was hired away by another company. His boss gave him a glowing reference helping him out the door.  8)
Quote
What sells and what does not sell is going to depend on the person doing the tweaking.
Results matter independently of how you arrive there. A design engineer does not randomly create a string of hits by chance, maybe once, but not over and over. I suspect there are some highly valued exotic amps that may be one hit wonders, where amp designers (cough) mostly tweaked other peoples designs and had some success.
Quote
Will taking a scope shot or measuring distortion at different frequencies tell you the answer?  Transient response using a square  wave? 
it can if you know what you are looking for... The repeat success guitar amp engineers I know were also EEs so no slouches about interpreting electrical measurements.
Quote
No.It is the designer who makes the difference. Not the specs or the circuit.  Why do you think James Brown suffered Eddie Van Halen?  :D
It was his job?  Since Jame Brown's office was literally a few yards from mine during this period I know a little about it, second hand from chewing the fat with James. He made multiple visits out to spend time with Eddie at his CA (home)studio, carrying prototypes in their various stages of development for Eddie to kick the tires on and critique. While Eddie's largest contribution was his name value he had a major say (and veto power) over all aspects of the amp. Eddie could not describe in technical terms what he wanted, so James translated his requests into a physical embodiment.  Without sharing any trade secrets Eddie's preferences ranged from choice of cabinet wood, to cabinet construction (which matters), gain staging, and more.  By this point James was already an experienced amp designer, but the 5150 was clearly Eddies vision of Eddie's ideal amp, translated to reality and brought to life by James.

Coincidentally James is now working for Fender on a new EVH project. What goes around comes around but apparently there is still some life in the EVH brand.

JR
Title: Re: TO-3P-3 replacements for 2n3055
Post by: CJ on February 14, 2020, 07:46:17 PM
the automobile came to life in 1886.

the integrated circuit in 1949.

the internet 1990.

 where do you think we will be in 1000 years?

in other words, right now, we don't know crap about anything.

to think otherwise would seem to indicate a lack of humility.
Title: Re: TO-3P-3 replacements for 2n3055
Post by: Whoops on February 14, 2020, 08:55:49 PM
I'm totally open to other opinions and people with other experiences.

So in your case CJ, is there any specific type of brand of 2N3055 that you prefer and why?
Or did you encounter any problems in replacing an old 2N3055 with a new production one?
Title: Re: TO-3P-3 replacements for 2n3055
Post by: JohnRoberts on February 15, 2020, 09:59:37 AM
the automobile came to life in 1886.
They only started talking to us recently (ignoring Kitt from Knight rider).
Quote
the integrated circuit in 1949.
The modern monolithic IC was perhaps a decade later...while there were earlier multi-device integrations, a precursor to the later technology.
Quote
the internet 1990.
I was using a modem on my computer to submit my magazine columns in the early 80s... Not exactly connecting to a world wide web, but days faster than using snail mail.
Quote
where do you think we will be in 1000 years?
dead and buried
Quote
in other words, right now, we don't know crap about anything.
The human race has accumulated a massive body of knowledge (just ask Alexa), while we rarely behave like it.   ::)
Quote
to think otherwise would seem to indicate a lack of humility.
Mea culpa? But I am regrettably still getting all too many reminders of my ignorance. I hoped by now it might slow down a little. I suspect I may be in Kelly Bundy mode where learning new facts, erases old knowledge.  8)

JR
Title: Re: TO-3P-3 replacements for 2n3055
Post by: CJ on February 15, 2020, 07:27:13 PM
these transistors right here are pulls from Marantz receivers.

i do not know who makes them. 

but they sound good. especially the ones with the aluminum domes.  just kidding. i can not quantify that with E=IR or F=ma or any other equations.

music is spiritual. electronics is material.   where they mix is where the fun is.
Title: Re: TO-3P-3 replacements for 2n3055
Post by: Whoops on February 15, 2020, 07:43:14 PM
these transistors right here are pulls from Marantz receivers.

Why do you pull them from Marantz receivers?
Is there anything in the circuit that makes them fail or are not sturdy enough?

Why do you replace them with MJ21194 and not with another 2N3055?

Thanks CJ
Title: Re: TO-3P-3 replacements for 2n3055
Post by: CJ on February 16, 2020, 03:40:15 PM
21194 is good to 250 volts so you have a bullet proof receiver since rails are 53 volts,



not sure why they fail, age, or maybe spikes from the speakers, they did use flyback diodes on later models.

those transistors are from 1975, most of them are still good, might have some leakage, we get a few blown ones from time to time.

music electronics blends art and science. you can be really good at the science part, but if not good at the art part, you will not put down a legacy.
Title: Re: TO-3P-3 replacements for 2n3055
Post by: Gene Pink on February 16, 2020, 05:31:54 PM
>  since rails are 53 volts,

>  not sure why they fail,

If you mean rails are +53 and -53, meaning 106V between rails, check the sec sheet out: 

https://components101.com/sites/default/files/component_datasheet/2N3055%20Transistor%20Datasheet.PDF

Or, as usual, am  I missing something?

Gene

Title: Re: TO-3P-3 replacements for 2n3055
Post by: Whoops on February 16, 2020, 06:00:43 PM
those transistors are from 1975, most of them are still good, might have some leakage, we get a few blown ones from time to time.

I might be missing something also
So if most 2N3055 transistors in those Marantz receivers are still good, and if blown ones are the rare exception, and if in your opinion the 21194 sound harsher,
why are you replacing the 2N3055 for 21194 at all?
Title: Re: TO-3P-3 replacements for 2n3055
Post by: JohnRoberts on February 17, 2020, 01:35:07 PM
>  since rails are 53 volts,

>  not sure why they fail,

If you mean rails are +53 and -53, meaning 106V between rails, check the sec sheet out: 

https://components101.com/sites/default/files/component_datasheet/2N3055%20Transistor%20Datasheet.PDF

Or, as usual, am  I missing something?

Gene
No you are correct... 3055 is generally hard to kill, but +/- 50V rails are a bit much for 60V devices.  The devices "should" be completely cut off when seeing >60V CE, but any reactive load, or even too much class A bias, could stress it outside its operational range.

JR
JR