Thanks Tim,
That sim program of yours saves an enormous amount of time, particularly with such an intriguing small "bunch o' bits"!
So, Rails of +/- 12volts, about 500 mA X 2 per channel = 24VA per channel - nice and solid, eh - no "toys"!
It will be interesting to hear how the different supplies effect the sound.
Should all those common connected Jfets have small isolation gate resistors?
Chokes: Most of the large size commercial ones that I've found are higher voltage units made for valve gear and the usual "large L, small C" designs have been for preamps and such - this load [1/2A X 2] doesn't fit into this category at all.
Is there such a thing as an "L multiplier"?!
About the bill - what do you need that we may have over here? [Apart from the AudioX which isn't available here, yet!]
Appreciate your time & effort - thanks again.
That sim program of yours saves an enormous amount of time, particularly with such an intriguing small "bunch o' bits"!
So, Rails of +/- 12volts, about 500 mA X 2 per channel = 24VA per channel - nice and solid, eh - no "toys"!
It will be interesting to hear how the different supplies effect the sound.
Should all those common connected Jfets have small isolation gate resistors?
Chokes: Most of the large size commercial ones that I've found are higher voltage units made for valve gear and the usual "large L, small C" designs have been for preamps and such - this load [1/2A X 2] doesn't fit into this category at all.
Is there such a thing as an "L multiplier"?!
About the bill - what do you need that we may have over here? [Apart from the AudioX which isn't available here, yet!]
Appreciate your time & effort - thanks again.
Nelson Pass said:If you Google "Fistwatt", you will get 9 references.
Argh, Freud you know.... but luckily i'm not the only one as googling FistWatt proves it...... ;-) Ant most of them are about YOUR product....
Anyway, did you get a free lunch with all of those more ??
There must be a price to it.
F1 rocks the bottom part of the sound spectrum, how does F5 compare to ? F3 is a close tube like sound, is F5 more classic Class A or more Class A like F3. Regards
Matching pairs
Matching pairs but unfortunately not matched pairs ? Would have been rather nice in such forum. Wwell schizophrenia does not help. ;-). Seriously, never noted this phenomenon, unless that occurs only on some computers..... argh,,,,, (how many pairs of this now ??)
Regards
jacco vermeulen said:
Matching pairs but unfortunately not matched pairs ? Would have been rather nice in such forum. Wwell schizophrenia does not help. ;-). Seriously, never noted this phenomenon, unless that occurs only on some computers..... argh,,,,, (how many pairs of this now ??)
Regards
jameshillj said:
You can add the small gate isolation resistor if you want.
Just a Biasing and Testing notes:
Test and bias each side with the the 15R resistors disconnected. when the sides are biased matched and tested then connect the 15R resistors.
You will have to tweak the biasing because your JFETs will be different from my sim JFETs. Make R134 R148 R102 R139 a 1k resistor in parallel with a 1K trim pot + 4k7 resistor.
Make sure the bias currents are identical between the left and right sides before connecting the 15R resistors.
Try to match the left to right sides of the amp as well as the top to bottom.
Don't worry about the the supply voltage will not effect the bias currents too much.
This amp is -3dB at 1MHz so be careful with your circuit layout and shielding.
If you want to change the gain, change R137 and R131. The circuit gain is (R150+R136)/R137.
[/NOTE]
If you could help me find some JFETs it would be much appreciated.
Cheers
Tim
F5 as populist amp
I completed the AX article. I loved the intro about gates and drains and water pipe references.
I suspect the fistwhat F5 will become a very popular DIY project.
It's got a small parts count, less power fets, and reasonable gain and output. It's not as strange by design as the others IMO. The 25W RMS makes it a popular replacement for the GainClone crowd, assuming the sound is anything like the F4 from reviews.
If Nelson sticks to his word (or my interpretation of it), than the next few are repeats with more power as monoblock projects, and the cheapskates may be left behind, or at least listening in mono.
I completed the AX article. I loved the intro about gates and drains and water pipe references.
I suspect the fistwhat F5 will become a very popular DIY project.
It's got a small parts count, less power fets, and reasonable gain and output. It's not as strange by design as the others IMO. The 25W RMS makes it a popular replacement for the GainClone crowd, assuming the sound is anything like the F4 from reviews.
If Nelson sticks to his word (or my interpretation of it), than the next few are repeats with more power as monoblock projects, and the cheapskates may be left behind, or at least listening in mono.
vdi_nenna said:
People 'round these parts will make you an amp out of a paper clip, tooth paste and a ball of twine if that's all they had. Bring it on!!!
I didn't mean to offend all the MacGyvers out there.
Your talking to someone who buys surplus heat sinks and mostly used music. Of course I pretend/try to be eco-concious...but really cheap cheap at heart
F5 is great poweramp
Few days ago, I complete my F5 project based on only this thread's info.
Now I use it, I can simply say it's great amp!!
The change point:
1. Power Voltage is 19V, bias is now set for 0.8A.
2. do not use R15,R16,TH1,TH2.
3. Q5 is changed to 2SA1020, Q6 is changed to 2SC2655
My impression:
1)Easy to set bias and very stable
I made ZV5 with JFET inputs before, but F5 is more stable.
That's very important point for PassDIY beginner I think.
I was very scared the bias setting of ZV5, but now I am not.
2)Very tight bass, clear mid and high
I prefer the sound of F5 than ZV5 with JFET inputs.
Now I'm happy with my F5.
Thank you for Mr.Pass, Your amplifier stimulated my creation mind.
Few days ago, I complete my F5 project based on only this thread's info.
Now I use it, I can simply say it's great amp!!
The change point:
1. Power Voltage is 19V, bias is now set for 0.8A.
2. do not use R15,R16,TH1,TH2.
3. Q5 is changed to 2SA1020, Q6 is changed to 2SC2655
My impression:
1)Easy to set bias and very stable
I made ZV5 with JFET inputs before, but F5 is more stable.
That's very important point for PassDIY beginner I think.
I was very scared the bias setting of ZV5, but now I am not.
2)Very tight bass, clear mid and high
I prefer the sound of F5 than ZV5 with JFET inputs.
Now I'm happy with my F5.
Thank you for Mr.Pass, Your amplifier stimulated my creation mind.
F5 specs
remarquable, like Adelph Oracle... Thanks
How noisy is the amps, is it close(r) to F3 (100uV, rather noisy when driving 106db horns) or to F2 (dead silent)?
Still have no idea about power and other spec (except that it is all more of everything.....), but i reckon i'll have to wait for the AXP article to come in the mail box or wait until it appears in FisRtWatt web site. Both fine
Regards
Nelson Pass said:
remarquable, like Adelph Oracle... ThanksHow noisy is the amps, is it close(r) to F3 (100uV, rather noisy when driving 106db horns) or to F2 (dead silent)?
Still have no idea about power and other spec (except that it is all more of everything.....), but i reckon i'll have to wait for the AXP article to come in the mail box or wait until it appears in FisRtWatt web site. Both fine
Regards
