F5 power amplifier

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#11,363
AndrewT said:
Using an F5's gain of 6times to a source signal of 2Vac takes the maximum speaker level output to 12Vac ~= 17Vpk. This is comfortably under the clipping voltage of an F5 driving a reactive 8ohm speaker load.
That 17Vpk into an 88dB/W @ 1m speaker gives a peak SPL of ~103.5dBpk @ 1m.
Click to expand...
Giving some meaningful math calcs to my data, thanks once again Andrew!

btw, a peak of 103.5dBpk, is it a peak of 106.5dBpk considering that, in fact, there are two speakers and not one?
 
#11,366
AndrewT said:
Using an F5's gain of 6times to a source signal of 2Vac takes the maximum speaker level output to 12Vac ~= 17Vpk. This is comfortably under the clipping voltage of an F5 driving a reactive 8ohm speaker load.
That 17Vpk into an 88dB/W @ 1m speaker gives a peak SPL of ~103.5dBpk @ 1m.
Again the sums show that the gain of the F5 suits those speakers and most Members listening conditions.
I can understand that one would prefer listening at the 12o'clock position, which could be anywhere between -3dB and -20db of attenuation.

Rixsta gave us nothing to compare to. His post was almost useless.
Click to expand...

Did you have any concerns to drive a Magnepan 1.7 or 3.7 with the F5?

Witch version of the F5c would you recommend (standard, four output devices and with/without cascade for the JFET input pair) ?
 
#11,370
Determining the "R" in CRC

Please help.

I am using BrianGT's power supply board for the Aleph.

I saw someone using several 0.47ohm/5W in parallel on this board, but it wasn't clear what value the capacitors were...

I plan to use it with 44,000uf/rail both before and after the "R",
How much resistance is needed for this CRC filter
which I'm building for my for my Pass F5 amp?

Thanks in advance!

-Chas
 
#11,372
clm811 said:
Please help.

I am using BrianGT's power supply board for the Aleph.

I saw someone using several 0.47ohm/5W in parallel on this board, but it wasn't clear what value the capacitors were...

I plan to use it with 44,000uf/rail both before and after the "R",
How much resistance is needed for this CRC filter
which I'm building for my for my Pass F5 amp?

Thanks in advance!

-Chas
Click to expand...
Lower resistance will give you lower output impedance. Higher resistance will give you more filtering. As zen zen sez, 0.1ohm (4x parallel 0.47ohm) uses to be a good balance.
 
#11,374
clm811 said:
Zen Mod wrote:


With all due respect, mind telling me what rule and who's thumb? 😕

Essentially, how did you calculate 0.1ohm (4x parallel 0.47ohm)?

I shall be grateful for your explanation! :goodbad:


Respectfully,
-Chas
Click to expand...
Sure.
Here, look at the formula of an RC low pass filter: f=1/2·Pi·R·C , quoting them "which is the frequency that the filter will attenuate to half its original power". So, the bigger the value of both the resistor and the capacitor, the lower the frecuency cut-off point. But the higher the resistor is, the higher the output impedance you get from the PSU...
 
#11,379
Good evening

Which has to be the maximal tension of exit(release) for the transformer of food(supply) of f5 can one use a tension superior(higher education) in 18vac such as on original plan.
I plan to use a tension enter 18 and 24vc before recovery and filtering what has to be the way?
Thanks to all
 
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