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Old 7th November 2015, 06:20 PM   #1
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Default Increase gain and output power of my F5?

I have a stock F5 amplifier (I bought it from FirstWatt a while ago). Since I changed to smaller speakers with lower efficiency (around 86 dB/W) I am thinking about my options to get a bit more oomph and louder music:
  • Can I modify the F5 for more gain (without reducing feedback / damping factor)?
  • Can I modify the F5 for more power (using the same chassis)?

I know this information is probably available in existing threads, but it's just way too much to read. It would be great if someone could lead me the way...
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Old 7th November 2015, 06:22 PM   #2
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-no
-no

don't use force , take bigger hammer
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Old 7th November 2015, 06:24 PM   #3
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- Why?
- Why?

How can I increase the size of my hammer?
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Old 7th November 2015, 06:36 PM   #4
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- no , without altering amount of NFB , which will lead to reducing DF

-no , without changing PSU to higher rails and most probably cascoding input JFets , when you are already in area of needing bigger heatsinks ; read F5 Turbo article to see what different levels are

easy ; first find Thor ......
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Old 7th November 2015, 06:38 PM   #5
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Quote:
Originally Posted by mbrennwa View Post
....options to get a bit more oomph and louder music.....could lead me the way...
The best way to optimal satisfaction are not on side of amplifier but speakers.
Solution 95 dB or more efficiency , amplifier have less hard work and play music louder
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Old 7th November 2015, 07:07 PM   #6
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Quote:
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- no , without altering amount of NFB , which will lead to reducing DF
Ok. Then I'll check if I can increase the gain of my preamp.

Quote:
Originally Posted by Zen Mod View Post
-no , without changing PSU to higher rails and most probably cascoding input JFets , when you are already in area of needing bigger heatsinks ; read F5 Turbo article to see what different levels are
Hmmm (page 3 in the PDF):
Increasing the power supply voltage is the obvious way to get more power out of an F5. You can simply raise the supply rails to +/-32 Volts and get 50 watts into 8 ohms right away without other modification.

Has anyone done this, is it worth it?

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easy ; first find Thor ......
Ok, ok, replacing my F5 with a F5T(hor) may be the way out. How much better would this be than just increasing the PSU voltage of my existing F5? Also, can someone recommend any F5-Turbo kits (PCBs, matched transistors)?
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Old 7th November 2015, 07:24 PM   #7
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Ok. Then I'll check if I can increase the gain of my preamp.
Surely your preamp has more than 6dB of gain already, or do you like the sound of a clipped amp.
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Old 7th November 2015, 07:54 PM   #8
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....

-no , without changing PSU to higher rails and most probably cascoding input JFets , when you are already in area of needing bigger heatsinks ; read F5 Turbo article to see what different levels are
.....
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Old 7th November 2015, 08:04 PM   #9
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When I used F5 with mid 80 db speakers I similarly needed bigger hammer. Building BA-3 preamp did the trick.

I did not experience any obvious clipping at reasonable levels. Likely pushed into AB at times.

Like someone else here said, get different speakers, if you must rock out.
Russellc
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Last edited by Russellc; 7th November 2015 at 08:10 PM.
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Old 7th November 2015, 08:09 PM   #10
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when you are already in area of needing bigger heatsinks
Not sure what you're trying to tell me. But my impression was that if I'd go for higher PSU voltage I'd have to lower the bias current in order to stay within the temperature / heatsink limits. I guess that would mean the amp would leave class A before reaching the max output power. Should I try that or is it a waste of time and money (I'd have to build a new power supply)?
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