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Old 16th February 2017, 01:39 AM   #1
andyr is offline andyr  Australia
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Default Is there a First watt model which can take a 2ohm load AND ...

has a power bandwidth (into 2 ohms) that extends to at least 50Khz?

I have come across a problem with the Mosfet amp driving my 2 ohm Maggie ribbons. It is 'stable' into 2 ohms - in that it doesn't blow up (although it gets warm) - but recent measurements have shown that the output voltage at 20Khz is only 73% of the output voltage at 6Khz ... and only 40% at 30Khz.

So it is not delivering equal power at all frequencies ... so is useless for my 2 ohms ribbons.

So I was hoping there might be a Pass circuit which has a power envelope up to 50Khz, for a 2 ohm load.


Thanks,
Andy
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Old 16th February 2017, 02:01 AM   #2
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F5 Turbo, most likely F4 and not Firstwatt BA3 with push pull output stage
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Old 16th February 2017, 02:27 AM   #3
andyr is offline andyr  Australia
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Originally Posted by 2 picoDumbs View Post
F5 Turbo, most likely F4 and not Firstwatt BA3 with push pull output stage
Thanks, mate. Reading the F5 manual - that seems to be the ticket. But I couldn't find any info on the 'Turbo' version?

And are these:
* fully mase up amps
* or kits which you buy from First Watt and solder?

Thanks,
Andy
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Old 16th February 2017, 02:46 AM   #4
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Originally Posted by andyr View Post
But I couldn't find any info on the 'Turbo' version?
Try find inside of :

http://www.firstwatt.com/pdf/art_f5_turbo.pdf

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Old 16th February 2017, 03:24 AM   #5
andyr is offline andyr  Australia
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Great - thank you very much!

Andy
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Old 16th February 2017, 03:38 AM   #6
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Pcbs are available from diyaudio store
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Old 16th February 2017, 03:41 AM   #7
andyr is offline andyr  Australia
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Pcbs are available from diyaudio store
Excellent - thanks!

Andy
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Old 16th February 2017, 03:45 AM   #8
rayma is offline rayma  United States
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Excellent - thanks!
I'd go with two mono amps on this one.
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Old 16th February 2017, 04:00 AM   #9
andyr is offline andyr  Australia
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I'd go with two mono amps on this one.
Yes, That is what I will be doing, Ray - my setup has an amp box containing 3 monoblocs, behind each Maggie.

Andy
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Old 16th February 2017, 04:02 AM   #10
rayma is offline rayma  United States
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Yes, That is what I will be doing, Ray - my setup has an amp box containing 3 monoblocs,
behind each Maggie.
Good, they'll get pretty hot, you know. Get plenty of air under and around them.
Read up on all the info available here and at FW before starting. Use the current, proven pcbs.

Last edited by rayma; 16th February 2017 at 04:06 AM.
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