Have you visited the First Watt web site? This is quoted from the home page:
"With oddball characteristics and output power ratings of 25 watts or less, First Watt is not for most people. If you have efficient loudspeakers, listen at reasonable levels and are obsessed about subjective performance, then you probably have come to the right place."
Each one is great in its own way. They are unique designs and none of them complex. First Watt amplifiers have only two gain stages, except the F3 which is single stage. It's very hard to pick one favorite, which is why many people end up building more than one.
Agreed. Said this earlier in thread but bears repeating...M2 seemed like easiest to me, bias setting itself, just dial down the offset and away you go.
Not to mention, I feel it is one of the best sounding of the ones I've built.
Russellc
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It is worth reminding that First Watt is a commercial venture catering to a niche market. Nelson Pass generously shares the schematics of discontinued products and provides details about design goals and decision making.
The ACA was also designed by Nelson Pass but it was meant as a beginners' amplifier. It is a good design but not intended as a commercial product.
The ACA was also designed by Nelson Pass but it was meant as a beginners' amplifier. It is a good design but not intended as a commercial product.
Yes, but it was never a commercial First Watt, either. Interested in seeing the new version however. For that matter, neither was BA-3 (or 2 or 1), really like my 31 volt rail complementary BA-3 amplifier....
Russellc
Sprags,
Do they sound different? Yes, absolutely, but remember we are comparing class-A amplifiers of similar power that use similar (or identical) active devices. The differences are in the topology.
As somebody who has built and heard a great deal of these, my recommendation is simply this - if you are more interested in trying single-ended, build the Aleph J, if you are interested in push-pull, build the BA-3 complimentary.
Or both.
Do they sound different? Yes, absolutely, but remember we are comparing class-A amplifiers of similar power that use similar (or identical) active devices. The differences are in the topology.
As somebody who has built and heard a great deal of these, my recommendation is simply this - if you are more interested in trying single-ended, build the Aleph J, if you are interested in push-pull, build the BA-3 complimentary.
Or both.
I've been sitting on my BA-3 Complimentary boards for a long while. I think the. Different variations and how to put everything together baffles my non electronic mind.
I'm thinking an amp with one board per channel plus the universal power supply, a transformer and few other components such as the speaker outputs, the RCA connectors, a switch, an IEC and maybe an LED would be something I can handle without screwing up.
I'm about finished with a Tubelab SSE (I hope) so I'm thinking a Class A solid state amp would be the next thing I could try.
My biggest concern is messing up soldering components on the boards. I think I've gotten pretty good at soldering but it's not something I do every day so....
I'm thinking an amp with one board per channel plus the universal power supply, a transformer and few other components such as the speaker outputs, the RCA connectors, a switch, an IEC and maybe an LED would be something I can handle without screwing up.
I'm about finished with a Tubelab SSE (I hope) so I'm thinking a Class A solid state amp would be the next thing I could try.
My biggest concern is messing up soldering components on the boards. I think I've gotten pretty good at soldering but it's not something I do every day so....
Agreed. Was a first time builder - built the ACA with own DIY enclosure and still enjoy it so much that the F2, F5 and F6 boards are still on the shelf. One day...
They are all easy circuits.
It's the small details that people often get stuck on. Ground loops, bad connections, poor solder joints, correctly wiring up things, drilling and tapping holes, time wasted on forgetting to order parts, what fasteners do I need, where do I get that from, what thermal pads should I use, what transformer should I use, what capacitors should I use, what IEC socket should I use, what fuses should I use, what gauge hook up wire should I use, copper, tin plated, or silver plated, how do wire all this up without killing myself ir destroying the amp, how tight is 1.1 Nm of torque, aah crap this is costing more than I thought, and taking much longer than I thought.
Hahaha
A year goes by and the project is still unfinished.
ACA less things to think about. Finished in a weekend.
It's the small details that people often get stuck on. Ground loops, bad connections, poor solder joints, correctly wiring up things, drilling and tapping holes, time wasted on forgetting to order parts, what fasteners do I need, where do I get that from, what thermal pads should I use, what transformer should I use, what capacitors should I use, what IEC socket should I use, what fuses should I use, what gauge hook up wire should I use, copper, tin plated, or silver plated, how do wire all this up without killing myself ir destroying the amp, how tight is 1.1 Nm of torque, aah crap this is costing more than I thought, and taking much longer than I thought.
Hahaha
A year goes by and the project is still unfinished.
ACA less things to think about. Finished in a weekend.
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I get it as far as all the extra time and effort needed for acquiring stuff. And since you can buy an ACA kit that includes everything mistakes regarding ordering the wrong parts won't happen but going from the ACA as the easiest which is the next more difficult amp? Or would you say the Aleph J, the F4 and the F5 are about the same?
As mentioned, there is no real difference in complexity between AJ F5 F4 F6, where the BA-3 has an extra board or two, but it's not that big a deal.
The thermistors in the F5 are a minor concern, just make sure they are touching the Mosfet.
The front end of the BA-3 is essentially a mini F5. The output stage of the BA-3 is identical to the F4 save the input buffer. Build it, and it's two birds with one stone.
The thermistors in the F5 are a minor concern, just make sure they are touching the Mosfet.
The front end of the BA-3 is essentially a mini F5. The output stage of the BA-3 is identical to the F4 save the input buffer. Build it, and it's two birds with one stone.
Zenmod suggested having the thermistors in very close proximity but not touching may be a better method, based on the possibility that if they are touching and one becomes detached (eg through thermal cycling etc) the result might be disastrous.
I think this is good advice.
If you look at close up images of F5 showing position of thermistors, I think Papa may have also done it this way.
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They could be in close proximity, touching through lead pressure if you bent them just right, and/or glued. I have seen examples of all methods, and they all seem to work. I prefer to bend them and have them touch, but a small spacing is also a good idea. I personally have not glued them.
You could just omit the thermistors, as the circuit works just fine without them, merely the warm up becomes slower and less stable. (I don't actually suggest this, however)
You could just omit the thermistors, as the circuit works just fine without them, merely the warm up becomes slower and less stable. (I don't actually suggest this, however)
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