F4 power amplifier

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#2,103
now that I have all the parts for a F4, I'm wondering if it's the best amp to build ... I'm working a pair of speakers that are shaping up to have the following specs:

about 3dB of BSC
-3dB response at 39 Hz
the woofer is ~86dB efficiency
sum is around 83dB/W/m

I haven't decided really on a proper preamp to drive the F4, so that could definitely be a factor in the equation.

Any opinions?
 
#2,107
luvdunhill said:
now that I have all the parts for a F4, I'm wondering if it's the best amp to build ... I'm working a pair of speakers that are shaping up to have the following specs:

about 3dB of BSC
-3dB response at 39 Hz
the woofer is ~86dB efficiency
sum is around 83dB/W/m

I haven't decided really on a proper preamp to drive the F4, so that could definitely be a factor in the equation.

Any opinions?
Click to expand...

Yep, you need a Pumpkin, and everything will be fine....

🙂
 
#2,108
Yep, you need a Pumpkin, and everything will be fine....
Click to expand...

Hey... Steenoe... I really hate myself, for discussing with the "big guys" in here 😉 ... But, if you don't have sources, with a lot of output, it dosen't do you any good (except soundquality ofcause).
What i mean, is that the Pumpkin is capable of swinging nearly 70Vac, but with a source giving perhaps 1,5Vac out, you still only will get around ~15V out (I think F4 need 25V to drive them max???)

Pumpkin or not, you really need some gain to drive speaker's around 83-86dB (Trust me i have been there with 87dB one's). Actually my Pumpkin with 2pcs. F4 full balanced monoblock's ain't capable of driving them anywear near limit.

I have just build, a pair of halfchang, with fostex fe207e (95dB), and with them the f4's really begin's to rock😀 ... But but still the volumeknob must be around 12-13 oclock.

Jesper.
 
#2,109
lykkedk said:


Hey... Steenoe... I really hate myself, for discussing with the "big guys" in here 😉 ... But, if you don't have sources, with a lot of output, it dosen't do you any good (except soundquality ofcause).
What i mean, is that the Pumpkin is capable of swinging nearly 70Vac, but with a source giving perhaps 1,5Vac out, you still only will get around ~15V out (I think F4 need 25V to drive them max???)

Pumpkin or not, you really need some gain to drive speaker's around 83-86dB (Trust me i have been there with 87dB one's). Actually my Pumpkin with 2pcs. F4 full balanced monoblock's ain't capable of driving them anywear near limit.

I have just build, a pair of halfchang, with fostex fe207e (95dB), and with them the f4's really begin's to rock😀 ... But but still the volumeknob must be around 12-13 oclock.

Jesper.
Click to expand...


just pump the gain of Pumpie
15x (23,5db) is completely same as 10x , for Pumpie ......... but not for F4 :devilr:
 
#2,110
lykkedk said:

But, if you don't have sources, with a lot of output, it dosen't do you any good (except soundquality ofcause).
What i mean, is that the Pumpkin is capable of swinging nearly 70Vac, but with a source giving perhaps 1,5Vac out, you still only will get around ~15V out (I think F4 need 25V to drive them max???)
Click to expand...

besides the Xono, which has lots of voltage, my digital source is rather wimpy.. it's 1.99V for both balanced and unbalanced outputs.
 
#2,111
You can adjust the Pumpkin's gain as you please🙂 Just study the Pumpkin CookBook carefully, or ask Mr. ZM directly. I beleive that 24dB gain is within reason? Furthermore, dont use lower railvoltages if you want to drive it to the max. (low input and low efficiency speakers)

🙂

BTW, The CookBook is a piece of art!
 
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