Since hifi2000 doesn't provide us with such data, the best we can do is to follow Papa's rules: always get the biggest heatsink you can, and after that use the palm rule! I have a small infrared laser thermometre, so that helps!
19.2 is pretty close to my estimated value of 20 after derating
I always knew deep down I couldn't be too dumb.
Hahahahaha
No need to lose sleep over this, I have that very case you are inquiring about, the heat sinks can easily do what you are asking them to do.
I have a bit of an odd question regarding the BA3 I built together with 6l6(Jim). I'd like to change out the 10uf caps on the input board to a smaller value, so that the amp will roll off the signal below 150hz.
What cap value should I change in order to make that happen? You might wonder why I want to do this.... its because my speakers run planar magnetic drivers for the midrange and I'd like to only send them a signal from 150hz and up. I have a separate bass section that has it's own amps, so I don't need a full range signal from the BA3.
I know that the formula to calculate this is:
1/RC = 6.3 * F
R= ohms
C = farads (not microfarads)
F = frequency
I know that F will equal 150, but I need to know the input impedance of the BA3's output boards (I'm using the complimentary, push-pull boards from the DIY Audiostore). Does anyone know their input impedance? Because that should give me R, and then I can calculate C.
What cap value should I change in order to make that happen? You might wonder why I want to do this.... its because my speakers run planar magnetic drivers for the midrange and I'd like to only send them a signal from 150hz and up. I have a separate bass section that has it's own amps, so I don't need a full range signal from the BA3.
I know that the formula to calculate this is:
1/RC = 6.3 * F
R= ohms
C = farads (not microfarads)
F = frequency
I know that F will equal 150, but I need to know the input impedance of the BA3's output boards (I'm using the complimentary, push-pull boards from the DIY Audiostore). Does anyone know their input impedance? Because that should give me R, and then I can calculate C.
Today I did a bit of listening to my newly built BA-3 (front end + power amp in separae chassis). I am impressed by dynamic, control, resolution, very delicate high frequencies, but comparing to Aleph J there is less colours, less presence and human voices sound a bit worse - is this something that can be cured by adjusting P3? I haven't touched it yet.
Aleph J sounds better at low volumes, BA-3 I kept increasing volume, it is very relaxed.
Aleph J sounds better at low volumes, BA-3 I kept increasing volume, it is very relaxed.
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Also you are hearing the differences between the AJ and the BA-3... The BA is pretty neutral whereas Alephs are quite colored, but the colors are so incredibly beautiful that nobody cares. 
The BA-3 is still my favorite amp, with the AJ in a very close second, despite their differences.
As ZM says, you can adjust P3 and tune to taste.
The BA-3 is still my favorite amp, with the AJ in a very close second, despite their differences.
As ZM says, you can adjust P3 and tune to taste.
Also you are hearing the differences between the AJ and the BA-3... The BA is pretty neutral whereas Alephs are quite colored, but the colors are so incredibly beautiful that nobody cares.
The BA-3 is still my favorite amp, with the AJ in a very close second, despite their differences.
As ZM says, you can adjust P3 and tune to taste.
Right, thanks. I need to replace heatsinks in the Front End as they are getting a bit too hot for my liking and then it's time for fiddling with P3
Went over to Jim's house yesterday and made 2 very nice improvements to my BA3.
1. Dialed up P3 to increase 2nd order harmonics. There's definitely a 'sweet spot' where the adjustment gives you the best results. And it's not "turn it all they way up". I'd say it was closer to "turn it up about 4/5ths" on my amp. Having good equipment to measure on is very nice because it allowed us to mirror the distortion curves very tightly on each channel.
2. Installed a ultra low noise transformer from Antek and a steel cover. And added some super-absorbent material for mechanical isolation. Here's a stock pic of case:
Net result? It is quiet!!! Like, you turn it on and you're like "is that thing actually on"? And it's heavier due to the larger transformer and the steel shield. It looks MEAN with the giant transfo cover, too.
And last but not least, it sounds just like a regular BA3 except more beautiful, thanks to getting the 2nd order harmonics dialed up. Which was the main goal of all this.
And a big shout out to Jim - man, you rock!
1. Dialed up P3 to increase 2nd order harmonics. There's definitely a 'sweet spot' where the adjustment gives you the best results. And it's not "turn it all they way up". I'd say it was closer to "turn it up about 4/5ths" on my amp. Having good equipment to measure on is very nice because it allowed us to mirror the distortion curves very tightly on each channel.
2. Installed a ultra low noise transformer from Antek and a steel cover. And added some super-absorbent material for mechanical isolation. Here's a stock pic of case:
Net result? It is quiet!!! Like, you turn it on and you're like "is that thing actually on"? And it's heavier due to the larger transformer and the steel shield. It looks MEAN with the giant transfo cover, too.
And last but not least, it sounds just like a regular BA3 except more beautiful, thanks to getting the 2nd order harmonics dialed up. Which was the main goal of all this.
And a big shout out to Jim - man, you rock!
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I'll let 6L6 answer that, as it was his equipment we were working on.
Sorry, misposted. I meant low noise transformer from Plitron.
It is quite common to increase the degeneration as output device numbers (in parallel) are increased.
Each degeneration resistor is effectively in parallel with it's neigbour. Thus 1r0 for one pair becomes 0r5 for two pair and 0r33 for three pair.
Lowering degenration resistors can lead to Thermal Instability and that will be exacerbated if the supply voltage is also raised. R.Cordell first discussed this in his "interviews Threads" and it is further covered in his book.
Each degeneration resistor is effectively in parallel with it's neigbour. Thus 1r0 for one pair becomes 0r5 for two pair and 0r33 for three pair.
Lowering degenration resistors can lead to Thermal Instability and that will be exacerbated if the supply voltage is also raised. R.Cordell first discussed this in his "interviews Threads" and it is further covered in his book.
Has anyone noticed that the schematic on the first page of Jim's build guide and on the store for the BA-2 shows only IRFP240's and no IRFP9240's? It also appears that the boards Jim used are different ones that are shown at the store. I know that both 240 and 9240's are used but some novice may not. Mute point actually if they are not in stock and maybe not stocked again. I am helping a fellow diy'er who has boards and noticed this fact. The boards Jim used shows N and P mosfets.
