Hi.Due to lack of confidence on others, i placed a new order at RS comp for some ST Tip3055(to-247). I believe tip3055 is good enough for JLH Class-A although no Ft spec in datasheet
I used the Bourns TIP2955/3055 in that package for a ESP project 3 clone amplifier I built for my HNC studies.
I don't know who acquired Bourns, but I expect the Ft of the ST is similar at about 2-3MHz
I used double the Transistors for a roughly 100W push pull amp, certainly one better for 4 Ohm loads, and a heatsink of about 0.5C/W maybe slightly less.
Good. I am glad my recall wasn't inaccurate!
Also testing my recall again, the to247 package is something like 90W verses 125W for to3, at least it is maybe 20% less capable.
So the rationale of doubling output devices was to mitigate this and spread the heat.
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On speed?
Yes, of course, Epitaxial by design is way faster than slow robust Hometaxial.
An advantage for Hi Fi design (NAD uses epitaxial 3055/2955 in some models with excellent results) but in my particular niche, a curse, Musicians regularly connect in parallel all cabinets they have available to a single amp out, use very high capacitance long screened guitar cables for speakers, replace broken plugs with new ones, no solder or iron involved, just twisting wire, use metal cap pugs without insulating the center connection, the works.
Give me strength over speed any day of the week.
EDIT:
Ok, even more in my favour
In practice difference is even larger: both 90W and 115W are fictional, impossible to achieve in practice , they are a poorly written representation of the real parameter which is Rth die to case.
Big Watt numbers look impressive and help sales , but are useless.
To keep case at 25°C and dissipating 90 or 115W, heatsink should be held below Zero °C ... do you think that´s realistic or achievable? (just do the Math, stated dissipation times typical 0.5°C/W case to heatsink Rth)
"Only in a Lab" [tm]
The single most unrealistic spec in any datasheet.
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TIP3055?
Yes, that´s fine.
Great for a , say, 30-40-50 W (tops) per channel Home Hi Fi amplifier.
Any higher use metallics or better spec´d transistors.
Two UR/USHA 2N3055H could deliver 100W RMS into 4 ohm loads with +/-42Vrails all day long, way above nominal datasheet ratings, but those were exceptional.
Same nominal spec ST? no way.
Yes, that´s fine.
Great for a , say, 30-40-50 W (tops) per channel Home Hi Fi amplifier.
Any higher use metallics or better spec´d transistors.
Two UR/USHA 2N3055H could deliver 100W RMS into 4 ohm loads with +/-42Vrails all day long, way above nominal datasheet ratings, but those were exceptional.
Same nominal spec ST? no way.
Can anyone GET a reliable source of 2N3055H for production use these days? And if so do they cost as much as an MJ15024 (from Mouser).
I can find 3055H or RCA house numbers which are derivatives of the 3055 on the surplus market from time to time, with prices ranging from good to “you want WHAT for it? Choke on it!”. But only hit or miss, and with the usual risk of fakes which is only mitigated by buy and try.
I can find 3055H or RCA house numbers which are derivatives of the 3055 on the surplus market from time to time, with prices ranging from good to “you want WHAT for it? Choke on it!”. But only hit or miss, and with the usual risk of fakes which is only mitigated by buy and try.
Truly 'exceptional' assuming modern epi based device. But today their price is really very high, around $12US/pair! With that money you can buy much better transistors today. Although i understand your point, the dissipation capability of to-3 is really very good i admit.
What do you mean by 'top'? You can expect more than 50w from a pair of tip3055 into 4ohm reliably. Around 75wRMS or so & that's a great value from $2.5usd/pair transistors.
Edit- The brand USHA is still functional, an age old & trusted company.
What do you mean by 'top'? You can expect more than 50w from a pair of tip3055 into 4ohm reliably. Around 75wRMS or so & that's a great value from $2.5usd/pair transistors.
Edit- The brand USHA is still functional, an age old & trusted company.
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Try to source genuine BEL transistors, they had their own shop on St. Marks Road in Bangalore, I still have ASZ17 purchased from there.
Now it seems to be in the Jalahalli plant in Bangalore.
BEL turnover 4.4 billion USD.
Have a friend do it, and send them to you.
They have o 100W version, 2N3055HV.
Now it seems to be in the Jalahalli plant in Bangalore.
BEL turnover 4.4 billion USD.
Have a friend do it, and send them to you.
They have o 100W version, 2N3055HV.
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Nah, i already ordered ST tip3055 & that's enough for my JLH Class-A. I was in search of slow output pairs similar to mj480.
I was suggested a current Indian source for USHA (or its succeeding company) 2N3055 H and at least the ones I used up to 2008 or so were VERY good.
I "would" order more today, just for stocking and repairing my old stuff floating around on the Market; I delivered more than 14000 amps along many years and they are tough as nails, many stay in use and now and then need servicing, here it´s not an exaggeration that "everybody had a Fahey amp", at least once.
A couple are currently in exhibition at our own National Congress, illustrating "the History of Argentine Rock" exhibition, go figure, together with drum sets, guitars, etc. used by locally famous Rock Stars.
But we have a schizophrenic Customs system, anybody can order anything .... as long as he orders "up to three" units .... any more and it´s presumed "for resale/commercial use".
So a boutique maker who is a friend had a bag with 100 carbon composition resistors stopped (total value $5 or $10) while in the booth right by him a girl was picking three laptops.
He complained: "inside each of them there is way more than 100 resistors" but the Customs guy was inflexible.
CRAZY!!!!!!!!!
So to make it worthwhile I need to order at least 300-500 transistors, and better pad the order with something else, because a "despachante de aduana", (customs dispatcher?), the registered guy who goes through all the paperwork charges a fixed U$400 fee.
Plus I need some registered importer number/code to be written in the invoice.
Now a guy who imports U$50000 of goods pays exact same fee.
Crazy.
You might order , say, 10 of them from India, from a regular shop, through normal mail or Courier, and test them real world, in the amps you intend to make prototypes, destroy them, cut them open with a saw (don´t trust MY word), etc.
When you are happy with quality, bulk order from a distributor or even Factory, if they will take it.
State of the art 2022 Market/Suppliers research
Obviously I would expect a good price for them, around 1U$ per unit, in quantity.
Do you need them for servicing old stuff or for a new product?
I use them for servicing old stuff. I scour the surplus market looking for stuff I can use, and build a stash for repair work and my own creations. I don’t make my money doing repair work, and when something comes my way it’s because they won’t pay more than the amp is worth to fix.
I was more curious about what you do if you’re stuck in the position of needing them because they’re designed in, and the required quantities don’t really justify a million dollar PO and the hassles of importing.
I was more curious about what you do if you’re stuck in the position of needing them because they’re designed in, and the required quantities don’t really justify a million dollar PO and the hassles of importing.
SOA on TIP35C isn’t wonderful - falls off really fast above 35 volts. And don’t push it either - they mean it. Grrrrreat for small-ish class H amps where they never see too much VCE while supplying current, but a NO NO for +/-50V class AB. Even two in parallel. if that D, E, and F aren‘t any better above 35V who cares if the VCEO is 160? But if they are REALLY the dies out of the old 2N5629, 30, and 31, THEN we might be getting somewhere. The s/b breakpoint on those is 35V too (according to the spec sheet), but it doesn’t fall as fast and they can really take more than their ratings.
Yes that's correct. One has to be very selective for BJT devices regarding SOA as it plays a very important role else the device will go into secondary breakdown. Thats why MOSFET are preferred as it do not suffer from secondary breakdown and drive is simple and very straight forward.