Nelson designed this amp, very very nice amp for class a/b, I don't know much about the circuitry. My question is that amp sounded great for class a/b, could those type of "can" transistors be used for a class A amplifier? Sorry for the "can" comparison but I don't know the correct term for the transistor.
Yes, but the output power would be lower because class A heat is less efficient than AB. More cooling is necessary to accommodate the greater heat dissipation.
ok they would get to hot with no way of cooling them, would be interesting if it could be done, they have a very warm sound, why I thought of them as possibly being used for class A
You'd need to design a new amp from scratch, using those output transistors with much larger heat sinks and much bigger power supply. It would make ~25% of the output power as the class B version with same number and type of transistors. ~75% of the power as heat.
The only reason to do it is of you love class A sound, or if you get chilly in the winter. 😛
Likely the sound of the 555 that you love has more to do with the overall amp design than it does with just the output transistors. All the stages and parts contribute to the end result.
Likely the sound of the 555 that you love has more to do with the overall amp design than it does with just the output transistors. All the stages and parts contribute to the end result.
Do love class A sound no doubt finishing up my f5 turbo v2, might be doing mono blocks next, lol my house is cold so a couple of hot amps wouldn't hurt a thing besides my electric bill which is already monsterous.
You could probably do it if you limited Class A power to 10 watts then the rest transitioning to Class AB
The bipolar Adcoms like the 555 are not such great candidates for dialling up the bias, but the mosfet Nelson-designed amps (5200, 5300, 5400, 5500, 5800, 5802) are superb candidates for making more class A if you can get rid of the additional heat and keep the ps ripple low.
I have been running a 5200 w 20W of class A (0.8A) for a few years now, but I added a bigger cap bank and a fan w additional hs.
I have been running a 5200 w 20W of class A (0.8A) for a few years now, but I added a bigger cap bank and a fan w additional hs.
I don't think he was referring to dialing up the bias of his existing amp, it seemed to me he was referring to the suitability of the transistors for a Class A design.
At least that is how I read what he is saying.
Yes I was wanting to build a class a with the can transistors, I will just tackle a v3 of the turbo, and leave the can transistor, as a faint memory lol.
And I'm pointing out that bottled up inside every 5400 is an F5 TWIN TURBO with the gain you're missing...
The "Can Transistors" are just the mounting package. (Known as TO-3) The silicon inside the can and the silicon inside the black plastic with the 3 legs (known as TO-247) is almost always completely identical.
If you are able to find IRF240/9240 in the TO-3 package, by all means build your F5Tv3 with them. If you have to build them with the TO-247 package devices, understand that it will be completely the same.
If you are able to find IRF240/9240 in the TO-3 package, by all means build your F5Tv3 with them. If you have to build them with the TO-247 package devices, understand that it will be completely the same.
The supply rails on the 555 are rather high for that. If you had lower voltages
you could think about upping the bias significantly.
With fans and such you could take it up a bit.
I thought that those transistors had a different sound, was my thought behind it, but if the 247 is the same I guess would be no point at all in doing it besides the obvious to be different.
IRF240/9240 are available in TO-3 (in limited amounts) from Newark, at the rather humorous price of $16.64 each. (The modern package is about $2.00 each. less in quantity.)
Handling heat is a function of proper heatsinking more than anything else.
Handling heat is a function of proper heatsinking more than anything else.
I have never owned a 5400, I can just say the 555 was fantastic, a poor mans way to own something that sounded good, but now thanks to Mr Pass we can own a class A amp for the price of a new 555, very cool guy for letting that happen. I was trying to talk my wife into us taking out a loan for a couple of the x series pass lab amps, so far no luck lol.
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