Fukushima and Futaba is commonly used in Japanese amplifier. I've seen a lot of Luxman uses Futaba plate resistor.
The resistive element shape is like serpentine, to lessen inductance. Cheers.
I biased mine at 400mV for a time, you will get more power, but what that equates to with your loudspeaker and loudness is impossible to say (output measurement doesn't tell you if an amplifier is going to be enough power, only how much power into a specified load)
I don't know that anyone has hung more output devices on the design, and that would require some other changes....
The other option is to go for dual monos.
Cheers,
Greg
I don't know that anyone has hung more output devices on the design, and that would require some other changes....
The other option is to go for dual monos.
Cheers,
Greg
I don't understand why you feel you need more power than 25W with speakers that are rated at 95dB/2.83V
If you never use more than 2W EVER not sure whether making your amp more powerful is going to lead to audio gains.
It would make more sense making your power supply super quiet and tough as nails.
Maybe you have other reasons to increase the power that I am not aware of.
Increasing power is as simple as going balanced (4 times more power)
Alternatively you could increase the rail voltages, but not sure whether the jfets are happy swinging voltages greater than 24V at the gate. You could take the jfets out if it were necessary.
I guess even if you never exceeded 24V signal peaks there is some benefit having some additional voltage drain to source, that is assuming you actually were swinging 24V peaks in the first place.
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It also depends on what's causing clipping. If it's voltage-limited with your speakers then you need higher rails (which might require cascoding the input stage). If it's current limited with your speakers then you need higher bias (which might require more output devices if you want them to have long lifespans). More output devices also equals more gate capacitance, so you may need predrivers (or switch to lateral FETs).
Either way you're going to need more heatsinking. Monoblocks are the obvious answer, though a 5U case might be enough.
[Cross-posted with pico. If anything is contradictory, go with his answer.
]
Either way you're going to need more heatsinking. Monoblocks are the obvious answer, though a 5U case might be enough.
[Cross-posted with pico. If anything is contradictory, go with his answer.
]
This is why most of my listening is with flea watts. Yes, you run into clipping, but it's rare.
What is the loudspeaker's design? Yours? Commercial? Can you biamp it? Does it have an unkind impedance profile at LF? If so, maybe a Zobel? If you can, that would be my first choice. Try some different high power amps to drive the woofer, then run the mid-high freq. drivers with the F4.
Cheers,
Greg
Ra7- are you wanting more power or more volume? It’s actually two different things.
When dealing with F4 volume is a direct function of how many volts your preamp can swing. If you want more volume, you need more gain in the preamp and it has to be able to swing 50v pk-pk (17.5vrms) into the input of the F4. If it can’t swing a signal that large, the F4 will never clip, so making any changes to the amp will not mean anything, as the limit is the gain/drive of your preamp.
Worth mentioning again, if your speakers really are 95db efficient, the full 25w of the F4 into your speakers will give a SPL of somewhere in the vicinity of 118db, and that’s not just loud, but damage your hearing loud.
To directly answer your question, you could increase the voltage a little of the amplifier itself, which would yield a few more watts because of increased voltage into the speakers, but you can’t go very much higher, since you’ll be above the ratings of the Jfets. Doing this, however, won’t make any difference in the volume you’ll get, since that is determined only by your preamp.
When dealing with F4 volume is a direct function of how many volts your preamp can swing. If you want more volume, you need more gain in the preamp and it has to be able to swing 50v pk-pk (17.5vrms) into the input of the F4. If it can’t swing a signal that large, the F4 will never clip, so making any changes to the amp will not mean anything, as the limit is the gain/drive of your preamp.
Worth mentioning again, if your speakers really are 95db efficient, the full 25w of the F4 into your speakers will give a SPL of somewhere in the vicinity of 118db, and that’s not just loud, but damage your hearing loud.
To directly answer your question, you could increase the voltage a little of the amplifier itself, which would yield a few more watts because of increased voltage into the speakers, but you can’t go very much higher, since you’ll be above the ratings of the Jfets. Doing this, however, won’t make any difference in the volume you’ll get, since that is determined only by your preamp.
Can't a guy want more power for no reason at all? Cheez!
Yes, the speakers really are 95 db/W. My own design, though not that uncommon. It's a 15" JBL woofer with a 2" JBL compression driver on a JBL waveguide. Passive crossover with FIR room correction. My other main speaker right now is a 24 driver line array using TC9 drivers. Both are easily in the 95 db/W region.
My current amp is an M2, which I find to be plenty powerful driving either speaker. I also have a UCD400 (close to 30 db gain) and it subjectively sounds more powerful (and objectively, it is). That doesn't make it better than the M2, of course.
So, I want more power just for the heck of it. Okay? Who knows what I might build tomorrow, or maybe I let my neighbor borrow it for his terribly inefficient speakers. Or, I just sleep better at night knowing I have all that reserve power.
I'll do some math and figure out how much voltage I can swing from the DAC, which is an RMI ADI-2 Pro, and using the 26 pre.
Greg mentioned higher bias at 400 mV or 0.85 amps per device. I guess that is it, then.
It will be on a 4U heatsink. Have some transformer options with 18V and 24V secondaries.
Yes, the speakers really are 95 db/W. My own design, though not that uncommon. It's a 15" JBL woofer with a 2" JBL compression driver on a JBL waveguide. Passive crossover with FIR room correction. My other main speaker right now is a 24 driver line array using TC9 drivers. Both are easily in the 95 db/W region.
My current amp is an M2, which I find to be plenty powerful driving either speaker. I also have a UCD400 (close to 30 db gain) and it subjectively sounds more powerful (and objectively, it is). That doesn't make it better than the M2, of course.
So, I want more power just for the heck of it. Okay? Who knows what I might build tomorrow, or maybe I let my neighbor borrow it for his terribly inefficient speakers. Or, I just sleep better at night knowing I have all that reserve power.
I'll do some math and figure out how much voltage I can swing from the DAC, which is an RMI ADI-2 Pro, and using the 26 pre.
Greg mentioned higher bias at 400 mV or 0.85 amps per device. I guess that is it, then.
It will be on a 4U heatsink. Have some transformer options with 18V and 24V secondaries.
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Yes, you can certainly have more power, nothing wrong with that!
I found that there was a tiny amount of warmth to the sound of the F4 at 400mV, but that was very likely my imagination. But, certainly added warmth to the room!
I thought about building a 7 channel UCD400 for home theater......
I found that there was a tiny amount of warmth to the sound of the F4 at 400mV, but that was very likely my imagination. But, certainly added warmth to the room!
I thought about building a 7 channel UCD400 for home theater......