Tell me, why do you need 3 pairs? What will they give you that you don't have with two? Again, they need to be selected so as not to produce unnecessary distortions, it seems...
Extra pairs of output devices give the amplifier better power handling. The output stage would would be very likely to fail with +/-63V rail voltage that it's designed for if it only had two output pairs.
Well, if just because of the supply voltage. I planned to supply +-40 volts. The SOT-323 input transistors do not give me pleasure to solder. But the difcascade and the current mirror with a double SMD transistor are said to be good. I haven't tried it . Is it really audible, or does it only affect the distortion?
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Jeff's right, two pairs are perfect for 100 wpc. For his supply voltages he does need more pairs.
-Chris
-Chris
I noticed the pairs too, but what got me more than that was how you intend to sink them being in the middle of the board like that?
You bolt the board and sandwich the transistors to the heatsink as one assembly. It saves space at the same time and makes the channels modular (if you want or need that)
With two pairs it's actually advantageous to mount the devices close together for thermal coupling so they share the load better. +/-40VDC rail voltage won't generate a lot of heat anyway. With more output pairs the center devices will run warmer causing current hogging though.
Speaking of thermal coupling you might want to rearrange the input transistors so you can stick Q1 and Q2 together.
I solve this issue differently. I cut off the convex part with a diamond file, bringing it to the plane. After that, thermal paste and heat shrink.
old cold war joke: the CIA stole blueprints for the T-14 "Armata" tank. Assembled - steam locomotive. Disassembled, assembled-steam locomotive! What to do, a Russian specialist was stolen. The specialist takes the drawing, looks, looks and says: "There is also a small font at the bottom: after assembly, modify by the rasp!"
Running
I spent the better part of a week going through it and learning the circuit as best i could. I also found values I didn't like in other area, so I replaced those as well. I just got done biasing it up to 40mA and all went well. Nothing hot no excessive voltages across the fuses, 8.25V across R14, DC off was just about zero without touching it. Biased it up and light started to come on and got bright, but that was expected at that point, it rolled it back lower and removed the light and reset the bias to and it looks good.
Tomorrow, I shall put everything back ion the chassis and check again. I can't get to the bias pot with it in the machine on that channel, so I shall match the other to the final numbers on this one.
Damn that was a bit of a deal. I know where every part is now without looking at the boar lmao.
Did id feel good to win? You bet your **** it did. 🙂 It took me longer to repair than it did to build.
I spent the better part of a week going through it and learning the circuit as best i could. I also found values I didn't like in other area, so I replaced those as well. I just got done biasing it up to 40mA and all went well. Nothing hot no excessive voltages across the fuses, 8.25V across R14, DC off was just about zero without touching it. Biased it up and light started to come on and got bright, but that was expected at that point, it rolled it back lower and removed the light and reset the bias to and it looks good.
Tomorrow, I shall put everything back ion the chassis and check again. I can't get to the bias pot with it in the machine on that channel, so I shall match the other to the final numbers on this one.
Damn that was a bit of a deal. I know where every part is now without looking at the boar lmao.
Did id feel good to win? You bet your **** it did. 🙂 It took me longer to repair than it did to build.
Did id feel good to win? You bet your **** it did. 🙂 It took me longer to repair than it did to build.
Been there and done that soooooo many times. Good Job!
I spent the better part of a week going through it and learning the circuit as best i could. I also found values I didn't like in other area, so I replaced those as well. I just got done biasing it up to 40mA and all went well. Nothing hot no excessive voltages across the fuses, 8.25V across R14, DC off was just about zero without touching it. Biased it up and light started to come on and got bright, but that was expected at that point, it rolled it back lower and removed the light and reset the bias to and it looks good.
Tomorrow, I shall put everything back ion the chassis and check again. I can't get to the bias pot with it in the machine on that channel, so I shall match the other to the final numbers on this one.
Damn that was a bit of a deal. I know where every part is now without looking at the boar lmao.
Did id feel good to win? You bet your **** it did. 🙂 It took me longer to repair than it did to build.
be deliberate, take things slow, and think over before you do....
i heard a guru say, "if you do not know the hows and the whys of what you are about to do, then do nothing..." this served me well thru the years....i still got a lot to learn though...
Ya, no kidding... I fired it up this morning checked my levels again and did a bit of tweaking. I broke out the gators and sent it input to test speakers. It's been running about 20mins at low/med levels on the one channel I repaired and it's sounds just fine.
I'll give myself a Bravo Zulu for the repair, but it was just stupid for it to get smoked in the first place.
Overall it was a frustrating learning experience. You always learn more when things go sideways than you do if all goes well.
JT
I'll give myself a Bravo Zulu for the repair, but it was just stupid for it to get smoked in the first place.
Overall it was a frustrating learning experience. You always learn more when things go sideways than you do if all goes well.
JT
I'm about to start bulding yet another honey badger. This time a 2ch amp for the fronts. And use the 5ch honey badger for center and rears. I've got most of the parts.
Ordered transformers to day. One 800VA 4x40Vac and one 20VA 2x12Vac for the DC protections. That was a little expensive. 270€ + 25% taxes. It better be silent 😀
The next big expense will be the 16x10.000uF caps.
Ordered transformers to day. One 800VA 4x40Vac and one 20VA 2x12Vac for the DC protections. That was a little expensive. 270€ + 25% taxes. It better be silent 😀
The next big expense will be the 16x10.000uF caps.