solid-state Bass amp

[lotus]

So I have a solid state bass amp using a pair of 2n3055 transistor for output. I want to remove these for another application and replace them with another pair of to-3 device. Does anyone have any suggestions for better substitute? More wattage is this possible Also I am a newbie regarding power amps but is it possible to sub with mosfet device or pnp device? Thanks

[Geek]

Hi,

Modding a SS amp for more power and newbie do not mix. Most old timers would give it a pass for the amount of work involved.

What amp is it and how many watts and how much do you want?

Cheers!

[lotus]

ya i'm removing the original motorola 2n3055 for a neve mic pre and I could replace with newer 2n3055 which I have. The transistors are not hard to access. I'm wondering if it's possible to replace with a higher fidelity to-3 device.

[Nigel Goodwin]

2N3055's are a perfectly fine transistor, and quality is already very high - they were commonly used in top HiFi amps back in their day.

You can't change either the power, or the quality, by just changing transistors, you need to redesign the entire amp, and while you could increase the power, you probably wouldn't improve quality, which doesn't need to be great for a guitar or bass amp anyway.

[lotus]

I see. more volume I don't need. I understand that 2n3055 was good back in the day. People change opamps for fidelity improvements. If I insert a npn to-3 device with the same ratings except higher-fidelity will it not increase transient response and punch?

[mjf]

hello.
once i saw transistor amps that used
bd 317 , and mj 15003 (and so on)................
try to measure the current amplfication (hfe or beta) of your 2n3055 ,and compare it with the new ones - the new should have equal or a little bit higher hfe.
have a look at the bias current (measure it before and after change ...).
have a look at the possibility of oscillations................
for more punch you can make the power supply bigger (bigger rectifier,bigger elco's)..........
greetings...............

[Nigel Goodwin]

Originally posted by lotus
I see. more volume I don't need. I understand that 2n3055 was good back in the day. People change opamps for fidelity improvements. If I insert a npn to-3 device with the same ratings except higher-fidelity will it not increase transient response and punch?

Unlikely to make any noticeable difference, particularly for an instrument amplifier.

Transistors don't have 'fidelity' ratings either.

[lotus]

"Transistors don't have 'fidelity' ratings either" I understand what you mean, however the nte to-3 transistors do have a fidelity rating in their recommended uses. So if transistors don't make a noticeable difference particularly in instrument amplifiers I guess all amplifiers sound the same. Bottom line is I have to replace existing transistor with something and I 'm trying to learn about output transistors for amplifier stages .

[Enzo]

There is a problem right there - using the NTE specs as a guide to anything. All their guides are useful for is determining which NTE part is closest to one you need to replace. It will tell you which of their parts is closest to yours. Sometimes you have a part you are not familiar with and googling the part number doesn;t help. You can often then find what NTE would REPLACE it with. Not what its specs are , but at least what NTE would have you use in its place. That isn;t the same as having the original specs, but absent those, it is better than nothing.

NTE makes a line of general purpose REPLACEMENT semiconductors. They are not exact copies, they are not the same parts. They may recommend certain of their transistors for audio applications, as opposed to switching applications or such things as pass transistors in power supplies or horizontal output transistors in TVs. It is not because some are "higher fidelity."

Guitar - and bass - amps do not deal in fidelity anway. You want to hear fidelity, plug your guitar into a PA system.

"So if transistors don't make a noticeable difference particularly in instrument amplifiers I guess all amplifiers sound the same."

No, instrument amplifiers all have their own sounds, they are designed to sound different one from another. But it is the whole system, not the particular transistors. On the other hand PA amplifiers ARE designed to sound alike, and they pretty much do. And they do it usung all kinds of different transistors.

[Nigel Goodwin]

Originally posted by lotus
"Transistors don't have 'fidelity' ratings either" I understand what you mean, however the nte to-3 transistors do have a fidelity rating in their recommended uses. So if transistors don't make a noticeable difference particularly in instrument amplifiers I guess all amplifiers sound the same. Bottom line is I have to replace existing transistor with something and I 'm trying to learn about output transistors for amplifier stages .

Different amplifiers have completely different circuits, it's the different circuit that make sthem sound differently, not a specific transistor.

If you've blown the 2N3055's then replace them with some more 2N3055's, there's nothing wrong with them. If you want something different?, try 2N3772's, they are higher rated as well - but it won't make it any more powerful, or sound better (it will possibly make it more reliable, if the 2N3055's are really been pushed).

In my opinion you can get 50-60W from a pair of 2N3055's, for a 100W amp you need to use four of them. 2N3772's can run at 100W on a pair, but I'd sooner see four of those as well.