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:
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...
- 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...
- 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 ......
-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 ......
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 🙂
Ok. Then I'll check if I can increase the gain of my preamp.
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?
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)?
Surely your preamp has more than 6dB of gain already, or do you like the sound of a clipped amp.
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
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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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)?
Better off reading F5T article. All 4 version are there, including original F5.
You'll need a larger transformer and higher voltage caps for F5T v1. Probably other changes as well.
You'll need a larger transformer and higher voltage caps for F5T v1. Probably other changes as well.
exactly, on all accounts
waste of money and nice amp originality
go and build properly new one , from scratch
Might close to impossible to sell, cause the market is flooded with F5 and it probably out of warranty.
The case has more value.
Have fun, take your time and do what you want. You paid for it.
The case has more value.
Have fun, take your time and do what you want. You paid for it.
I'd be willing to pay a $1000 for a 2nd hand F5 built buy Papa, purely as a reference to compare with my own designs.
Your amp has around +/-23VDC rails at this time. and the PSU have 25V caps. how much can you raise the rail voltage?
so you need new caps and new transformer. just to get a lower biased class A/B amp? or you can get a New chassis as wel. but then the output transistors will stop you in your way. best to stay within 30W dissipation pr output. you can og higher at lifetime cost.
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How loud are you listening and how big is the room? Have you tried putting a voltmeter set to ac on the terminals and seeing how many watts you are actually using when listening loud? You may need current, not more wattage. Especially if the speakers are 4 ohm or have low impedance dips.
keep your FirstWatt for efficient speakers. and go DIY for your low efficency speakers.
Don't bugger up your factory FirstWatt.
Ok, I am considering a new build:
I want about 50W to 100W in the 4-16 Ohm range. With rail voltage of +/-40VDC and a total idle current of 5A, I calculated the following effective output power:
- 50W at 16 Ohm and 100W at 8 Ohm (voltage limited)
- 50W at 4 Ohm (class-A, current limited), and more if going to class B is allowed
- The heat dissipation would be 2*40V*5A = 400W for a monoblock
First question: do these number seem correct?
Second question: how many output device pairs do I need? I could use many device pairs at a low idle current each, or I could use fewer pairs at a higher current. Which is better (soundwise and from an engineering perspective)?
I want about 50W to 100W in the 4-16 Ohm range. With rail voltage of +/-40VDC and a total idle current of 5A, I calculated the following effective output power:
- 50W at 16 Ohm and 100W at 8 Ohm (voltage limited)
- 50W at 4 Ohm (class-A, current limited), and more if going to class B is allowed
- The heat dissipation would be 2*40V*5A = 400W for a monoblock
First question: do these number seem correct?
Second question: how many output device pairs do I need? I could use many device pairs at a low idle current each, or I could use fewer pairs at a higher current. Which is better (soundwise and from an engineering perspective)?
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