Read carefully, guys.Let us discuss the design of this Amp with picovolts of noise at the output.
A little easier to achieve then picovolts 😀The output noise is around 100 picowatts
Duck-Twacy said:firstwatt.com is not reachable at the moment....
Under construction
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It's working for me.
se
This amp must of occured to Mr. Pass while developing and fine
tuning the J-Low speakers. Since the F1 seems to play well with
high pass filters and full range cone speakers, that need the
filtering to be able to boost output. At least that's the idea i got
reading the website. Although i seem to remember Mr. Pass
mentioning that 10 watts might not be enough power. Maybe a
power current source amp doesn't have the same limitations as
normal amps. (i think i may be in over my head here!) 🙂
How would this amp sound with my Straight 8's? ...maybe better
if i had an external crossover?
m.
tuning the J-Low speakers. Since the F1 seems to play well with
high pass filters and full range cone speakers, that need the
filtering to be able to boost output. At least that's the idea i got
reading the website. Although i seem to remember Mr. Pass
mentioning that 10 watts might not be enough power. Maybe a
power current source amp doesn't have the same limitations as
normal amps. (i think i may be in over my head here!) 🙂
How would this amp sound with my Straight 8's? ...maybe better
if i had an external crossover?
m.
Interestingly, he mentions Lowther and Fostex drivers, but not the Jordon drivers in the J-Low. The Jordons are not particularly efficient, so you are probably right. However I do remember Nelson mentioning using a Zen enlightened amp or whatever the one with lightbulbs is-and that was about 10 watts also. I'll bet that it works fine with the J-low in normal listening.
He also mentioned I think that this current (haha) amp is going to be quite expensive. Does it make sense that it might have the monster choke that the recent Zen amps have?
He also mentioned I think that this current (haha) amp is going to be quite expensive. Does it make sense that it might have the monster choke that the recent Zen amps have?
Nelson, has anyone told you that you're a sick puppy?
Grey
(Wish I had enough room for projects that big...)
Grey
(Wish I had enough room for projects that big...)
Whooohooo!! Looks like something a Heating/ AC sheetmetal guy could make!
Buhahaahahhahahah (did I get it right?) just amazing!

Buhahaahahhahahah (did I get it right?) just amazing!

Nelson Pass said:This is what you do with 10 watts.
Not bad. Not quite as elegant as the originals (Be Yamamura's Dionisio 27s), but not bad.
An externally hosted image should be here but it was not working when we last tested it.
se
woody said:But why didn`t you mirror immige them ?
I don't get it. Far as I can see, they are mirror images of each other. Where's the asymmetry I'm missing?
se
I always liked the large Western Electric snail horn with the 594 driver. Thats an amazing piece of gear!
Mark
Mark
I have just read what the F1 is stuff like. How do the speakers /normally they are voltage driven electro-acoustic transducers, and their characteristics are valid only for voltage drive/ enjoy current drive? This should result in poor damping and much worse frequency characteristics compared to voltage drive.
PMA said:I have just read what the F1 is stuff like. How do the speakers /normally they are voltage driven electro-acoustic transducers, and their characteristics are valid only for voltage drive/ enjoy current drive? This should result in poor damping and much worse frequency characteristics compared to voltage drive.
See:
It is well suited to sensitive full-range drivers such as Lowther or Fostex, and allows easy use of parallel loading networks to tailor the driver response.
I think "allows" is a bit of a misnomer. Unless you want a big hump in your bass response (as you increase source impedance, your response starts to resemble the driver's impedance curve), seems to me the loading networks would be pretty much a necessity.
Either that or you'd have to increase the mechanical losses in the driver.
se
Steve Eddy said:
See:
It is well suited to sensitive full-range drivers such as Lowther or Fostex, and allows easy use of parallel loading networks to tailor the driver response.
I think "allows" is a bit of a misnomer. Unless you want a big hump in your bass response (as you increase source impedance, your response starts to resemble the driver's impedance curve), seems to me the loading networks would be pretty much a necessity.
Either that or you'd have to increase the mechanical losses in the driver.
se
Oh - I see at least 2 advantages:
1) you can tailor the driver response by means of parallel network,
2) you can get great bass from small output power utilizing speaker resonance.
Have you already bought one?
Steve Eddy said:Either that or you'd have to increase the mechanical losses in the driver.
Current amps worls best with drivers with inherent mechanical damping -- lowthers are an example.
dave
PMA said:Oh - I see at least 2 advantages:
1) you can tailor the driver response by means of parallel network,
Sure, you can do that. But given that one of the main appeals of full range drivers such as the Lowthers and Fostexes is that they can be used without any intervening electronics between the amplifier output and the driver, I'm not sure that many will consider that an "advantage."
"Gee, I didn't have to have all that stuff in there before." 🙂
2) you can get great bass from small output power utilizing speaker resonance.
How do you figure the small output power? Don't forget that there's an impedance peak at the driver's resonant frequency.
Let's say our current source amplifier is outputting about 350 milliamps RMS. Into 8 ohms, that's about 1 watt. But at the speaker's resonant frequency, the impedance will be significantly higher than 8 ohms. 100 ohms is not unheard of. So using a speaker with an impedance of 100 ohms at resonance as an example, shoving 350 milliamps into that comes to 35 watts.
Have you already bought one?
Not yet. 🙂
se
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