With +/-32V supply, 3A total bias and 8 Ohm load, you should have (theoretical values):
Peak power: (32*32)/8= 128W --> 64W RMS
Class A power: 8*(3*2)^2= 288W --> 144W RMS
Heating power: 64*3= 192W
First of all: please someone confirm this
Then I would like to have some clarifications: in this case the class A power is greater than the RMS power. Does this mean that the bias is "too high"? Is it right to set the bias so that the class A power equals the amp power?
You won't get rail to rail voltage swing unless you run the front end at more than 32v. Therefore the voltage limit will be a little less. Perhaps reaching +/-28V peak, 98W peak and 49 W RMS. As 6L5 said earlier, about 50W.
Your class A power calculation uses peak current, not RMS. The peak class A current is twice idle with a push pull circuit. That's why it looks so odd. Divide by two to get RMS and the voltage and current limits come a lot closer together.
There's no such thing as too much bias. There are many examples of circuits that sound better when the voltage is the power limit than the current capability. Aleph circuits in particular.
Your class A power calculation uses peak current, not RMS. The peak class A current is twice idle with a push pull circuit. That's why it looks so odd. Divide by two to get RMS and the voltage and current limits come a lot closer together.
There's no such thing as too much bias.
There are many examples of circuits that sound better when the voltage is the power limit than the current capability. Aleph circuits in particular.
Assuming you can swing all the way to the full 32V rails (which you can't with 1ohm source resistors...) It will make lots of power.
But let's be just a little optimistic and say you can get +/-30V, or 60V Pk-Pk
60V Pk-Pk * .3535 = 21.21V RMS
21.21 ^2 = 450
450/8 = 56W RMS into 8Ohm
450/4 = 112W RMS into 4Ohm
My experience says you will be just a little short of that, but close enough to not matter.
The BA-3 is a very powerful, clean, smooth, detailed, and lovely amp. I really like it. It has Bass in a way that an Aleph doesn't, tuneful and powerful. (The aleph is very pretty and musical, but could use a bit more oomph)
I'm sure you will be happy with a 50W BA-3
But let's be just a little optimistic and say you can get +/-30V, or 60V Pk-Pk
60V Pk-Pk * .3535 = 21.21V RMS
21.21 ^2 = 450
450/8 = 56W RMS into 8Ohm
450/4 = 112W RMS into 4Ohm
My experience says you will be just a little short of that, but close enough to not matter.
The BA-3 is a very powerful, clean, smooth, detailed, and lovely amp. I really like it. It has Bass in a way that an Aleph doesn't, tuneful and powerful. (The aleph is very pretty and musical, but could use a bit more oomph)
I'm sure you will be happy with a 50W BA-3
Jim, it seems power and bass are the most often discussed topics with the NP designs. Since you have heard and/or built just about all of them, can you share your impressions on how the top end compares between say - F5, Aleph and the BA family. I understand clarity and lack of distortion are hallmarks, but do you hear any particular inherent flavor or signature in the upper register that warrants comment?
I'm thinking like cymbal sizzle, realistic fret sounds or other elements that contribute to a sense of presence. I'm suspecting the Aleph (the one I haven't built yet) may get the edge, but not sure.
(hope this is a proper place to ask and not intrusive)
I'm thinking like cymbal sizzle, realistic fret sounds or other elements that contribute to a sense of presence. I'm suspecting the Aleph (the one I haven't built yet
) may get the edge, but not sure.(hope this is a proper place to ask and not intrusive
)
The upper registers isn't where the various designs differentiate themselves, in my opinion... bass reproduction seems to be the most obvious difference. The BA-3 and F4 have the most oomph, the F5 has less, and the Aleph has the least, mainly due to it's (relatively) high output impedance.
But in that 3-5K and above range I wouldn't really say there is anything that is noticeably better or worse than the rest. The Magic is in the midrange, and they are all so fantastically good at those frequencies that most people who build one can't believe how 'bad' their old amps sound. Like I said, the most obvious subjective (an objective) differences are in the bass. BUT that is something that is dominated so strongly by your room nodes that the amp performance is kinda an afterthought.
I'm thinking like cymbal sizzle, realistic fret sounds or other elements that contribute to a sense of presence. I'm suspecting the Aleph (the one I haven't built yet
Well, sorta. If you want more of that HF zing and air like what you describe, I suggest deceasing the resistance of the series resistor in your tweeter xover by about an ohm. The amps will all do what you want - they are all as clear as a mountain morning, and although the Aleph is probably the best at what you describe, they are all pretty much equal in that regard.
I am after the amp that gets me closest to the music. I want to forget I'm listening to my stereo and just enjoy it. I could give a rat's posterior about all the normal audiophool drivel and verbage, and want the amp that will get me singing along to the song, or the one that make it feel like only a few minutes have gone by and I have to flip the record.
ALL the firstwatt amps I've made do that in spades. Every one. The biggest propblem with comparing the F5 to F4 To Aleph to BA-3 is much akin to going to look and drive all the cars in this photo and choosing which one is the most red Italian sports car --
See the problem? They are all awesome in their own way.
Even though it is a power amp, any reason why I couldn't place a potentiometer on the input and some source selection solution, and call it an integrated?
I've seen the ba3fe + crippled f4 recommended as pre+ power solution and the ba3 is basically just that right? The first solution saves a case and interconnects from the system.
I've seen the ba3fe + crippled f4 recommended as pre+ power solution and the ba3 is basically just that right? The first solution saves a case and interconnects from the system.
Thanks Mr. 6, that's the confirmation I was seeking. With my limited experience (ACA-F5-BA3) I haven't heard a standout in the top end - meaning consistent and that's a positive. Lots can be done on either side of the power (output) amp to adjust the 'flavor and tone' so I won't look for something that's not there.
A couple weeks ago I pulled out my 15 year old Vifa MTMs, and with the BA-3 the system is dramatically different in character - which aligns with your XO comment. Completing the complementary outputs might tweak the BA a bit, but I'll concentrate on the fuel injection, exhaust manifold and hub caps on my sound chariot.
BTW- just saw the fun new NFS movie, so planning to paint some blue stripes on mine for competitions...... red is old school.
A couple weeks ago I pulled out my 15 year old Vifa MTMs, and with the BA-3 the system is dramatically different in character - which aligns with your XO comment. Completing the complementary outputs might tweak the BA a bit, but I'll concentrate on the fuel injection, exhaust manifold and hub caps on my sound chariot.
BTW- just saw the fun new NFS movie, so planning to paint some blue stripes on mine for competitions...... red is old school.
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I have used a Creek passive with the BA3 and it works very well. Just looking at a Philips Bluetooth with audio hifi output device that can be had for £25 to use with my Google Nexus7. I would hope the volume could be controlled from the Google. If I try it I'll let you know.
If you haven't seen it take a look at "Gozmo" from Jriver. It has complete function control using Android phones. Works great with both on-line services and with media stored at home on PC hard drives.
I would disagree with Jim.
For me, the AJ offers something the other two amps do not, when it comes to the midrange and top end. It is silky smooth, with plenty of air, and just the right amount of bloom in the midrange. If i could pick a shape to describe the soundstage it creates, I would pick a bubble, if that makes sense. Its a big, soft, busty woman, that you just want to grab and snuggle with. Yes I said snuggle
The F5 is my least favorite amp of the FW series, but it is not because it is bad, it just does not have a personality. IT offers nothing but reproduction and just tend to like a little syrup with my ice cream. It does nothing wrong and arguably performs well in all regards, but it does not offer me something to get excited about. It does not seem to excel in anything, but is good at everything.
The F4/(whatever FE, in this case, BA3 or BA3B) is more similar to the F5, but the ability to add some toppings. You can just play with the Ba3 FE by changing fets or by tweaking sound with P3, or go further and dive into Leaving CLass A article. It is a twiddlers amp and has the abilty to variations in sound. By far the most versatile of his amps, and under capable hands, has a lot of upside potential, if you consider some commercial offerings. Unfortunately, this takes skill beyond my level and beyond that of most who build these amps.
Of the FW amps I have built, the AJ is top 3, maybe 2 in terms of lasting impression it made on my auditory memory.
For me, the AJ offers something the other two amps do not, when it comes to the midrange and top end. It is silky smooth, with plenty of air, and just the right amount of bloom in the midrange. If i could pick a shape to describe the soundstage it creates, I would pick a bubble, if that makes sense. Its a big, soft, busty woman, that you just want to grab and snuggle with. Yes I said snuggle
The F5 is my least favorite amp of the FW series, but it is not because it is bad, it just does not have a personality. IT offers nothing but reproduction and just tend to like a little syrup with my ice cream. It does nothing wrong and arguably performs well in all regards, but it does not offer me something to get excited about. It does not seem to excel in anything, but is good at everything.
The F4/(whatever FE, in this case, BA3 or BA3B) is more similar to the F5, but the ability to add some toppings. You can just play with the Ba3 FE by changing fets or by tweaking sound with P3, or go further and dive into Leaving CLass A article. It is a twiddlers amp and has the abilty to variations in sound. By far the most versatile of his amps, and under capable hands, has a lot of upside potential, if you consider some commercial offerings. Unfortunately, this takes skill beyond my level and beyond that of most who build these amps.
Of the FW amps I have built, the AJ is top 3, maybe 2 in terms of lasting impression it made on my auditory memory.
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