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Old 15th June 2013, 02:18 AM   #13161
Rush is offline Rush  United States
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Quote:
Originally Posted by Rixsta View Post
12v F5 possible, using 2x 12v batterys ?
Possible. But the voltage will drop the whole time you listen and the sound will change and the bias may not be stable or at least not where you thought you wanted it.
Sweet spot will pass by in a cut or two.
It would take a massive set of batteries for any length of listening time.
For the money you would spend on batteries, do a great big ole power supply like Mr. Pass suggests, with a huge transformer VA rating.

I have a Mac Mini music server that I have powered with a 12 volt regulated power supply with a battery backup (when you pull the plug on the supply, the batteries are connected directly to the 12VDC output) and although it pulls less than an amp, it draws the two 12 AH 12 volt batteries down from the charged voltage of 13.4 VDC to 12.3 VDC within a CD of listening and you can hear the difference (higher voltage sounds better). It is smother though at first and but the sound stage starts to collapse as the voltage drops. It doesn't take long before I am plugging it back in.
I also have a straight regulated supply that has been tweaked that sound better anyway.

Rush
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Old 15th June 2013, 02:56 AM   #13162
6L6 is offline 6L6  United States
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Quote:
Originally Posted by Rixsta View Post
12v F5 possible, using 2x 12v batteries ?
If you have 50Hz hummm you have an input loop or signal loop problem, not PSU.

PSU problems are almost always twice the mains frequency, because you are rectifying both sides of the 50Hz AC, charging your caps at 100Hz.

Remove the B1 from the amp for the time being.

Also look at your output wiring, you really should take the speaker output from the center board. (Yes, I know that there are not enough solder holes to do that conveniently...)

But, if you want a battery powered F5, get 4 batteries, stack them and make it 24V+24V
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Old 15th June 2013, 03:53 AM   #13163
lhquam is offline lhquam  United States
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Quote:
Originally Posted by Rixsta View Post
12v F5 possible, using 2x 12v batterys ?
If you are willing to go to the Balanced-F5 such as here Balanced F5 in a Small Footprint then you should be good for around 25 watts into 8 ohms.
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Old 15th June 2013, 10:41 AM   #13164
Rixsta is offline Rixsta  United Kingdom
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Not too bad with the right speakers or for Trebble down to Mid-bass, then another amp for the low bass, perhaps.
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Old 18th June 2013, 11:32 PM   #13165
bcmbob is offline bcmbob  United States
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Wanna see a "COOL" F5 ?
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Old 19th June 2013, 12:36 AM   #13166
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I like it.

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Old 19th June 2013, 12:43 AM   #13167
bcmbob is offline bcmbob  United States
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Thank you Mr. Pass. That means a lot. Your contributions to the diy audio world are greatly appreciated...... and it's a lot of fun.
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Old 19th June 2013, 12:49 AM   #13168
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realy nice
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Old 26th June 2013, 10:30 PM   #13169
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My F5 was blowing fuses on power-up.

I was using 1.25A slow blow fuses and it worked for several power-ups before the first one went. Then for some reason I could barely get the thing on without it popping them, so I tried a 1.6A slow blow, whihc seemed to resolve my problems for a few days and a few power-ups, but then these again started popping on turn on, and having got though 5 in a row, I went up to 2A slow blow, which is now working fine.

I have a 300VA toroidal, with 240v primaries (not two 120vs joined as it is a UK manufactured toroidal). I see on Nelson Pass's diagram that 1.25A is recommended for 240v supplies and 2.5A for 120v supplies.

Is there anything I can try without resorting to my current (pun intended) 2A fuse? It seems stable now, but maybe even these will blow in time? Curious!

Thanks
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Old 26th June 2013, 10:36 PM   #13170
6L6 is offline 6L6  United States
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You could use a 'soft-start' circuit, which would keep the fuses intact.

Do you have the CL-60 in the transformer primary?
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