F5m kit

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northpaw

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Joined 2016
Lewisknox said:
Is the 200 VA Trans OK also from Antek?
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If the answers above still leave doubt, I used the 200VA Antek and I feel my unit works fine. I had 24V rails unloaded, and only checked them again after it was running for several days, and remember being surprised that they measured lower when loaded. I think between 21-22Vdc, and I can't check now as I am traveling. And as mentioned above, there is the benefit of the bias current running higher for a given dissipation.

Also remember that Nelson approved of the 200VA 18V Antek in his write up. So there isn't any question that the F5m will work well with it.
 
twofires

twofires

Member
Joined 2022
Holzarbeiter said:
twofires:

That answers my muddy questions very well. I just ordered the parts before knowing this from Digikey and was wondering what I should do now before the 'second' kit arrives. More parts for the spares.

Do you think the board 5) Therms are a different value then the 1) ground lift Therm.?
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My assumption is that when @WBS says (emphasis mine) "Thermistors will be Ametherm 10 Ω 8A 22mm", they mean all of them. I'm hanging a lot on pluralisation there, though.
 
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Jason

Jason

Switches things on and off again
Joined 2000
diyaudio.com
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Holzarbeiter said:
why is the picture still showing the old board
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New (nice) photos take several weeks to organize, and we know you'd rather not wait :) Moving forward, for the first few batches of any new kits we will likely be moving towards not-so-nice but more up-to-date photos. Or a note of "Photo is of R1" and the description details that the kit being sold currently is R2, etc. This is also an issue in regards to build guide photos with parts changing from batch to batch based on availability.
 
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Z

zman01

Member
Joined 2011
northpaw said:
If the answers above still leave doubt, I used the 200VA Antek and I feel my unit works fine. I had 24V rails unloaded, and only checked them again after it was running for several days, and remember being surprised that they measured lower when loaded. I think between 21-22Vdc, and I can't check now as I am traveling. And as mentioned above, there is the benefit of the bias current running higher for a given dissipation.

Also remember that Nelson approved of the 200VA 18V Antek in his write up. So there isn't any question that the F5m will work well with it.
Click to expand...

Mr. Pass mentions 1.1A max bias for use with a 2U heat-sink; a 200VA power transformer would be sufficient for the amplifier running at 1.1A bias.

Dropping ~2V on the rails is common when operating under load for a Class A amplifier.
 
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barossi

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Joined 2003
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twofires

twofires

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Joined 2022
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e_fortier

e_fortier

Member
Joined 2001
northpaw said:
If the answers above still leave doubt, I used the 200VA Antek and I feel my unit works fine. I had 24V rails unloaded, and only checked them again after it was running for several days, and remember being surprised that they measured lower when loaded. I think between 21-22Vdc, and I can't check now as I am traveling. And as mentioned above, there is the benefit of the bias current running higher for a given dissipation.

Also remember that Nelson approved of the 200VA 18V Antek in his write up. So there isn't any question that the F5m will work well with it.
Click to expand...
For folks looking for a deal on a 200VA, I recently bought the following transformer for another project. I offered the seller $30 and he accepted it.

200VA eBay
 
birdbox

birdbox

Member
Joined 2014
Well F5m sold out and instead of 36 minutes, it was over 36 hours! That was a good run this time around. I hope to see Greedy Boyz builds from all over the world soon on this thread. Glorious music for all.

I'll also add a big Thank You to all the folks who make these awesome projects possible; Papa, WBS, Jason, Elena, and the rest of the DIY Audio team!!!!
 
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seventenths

Member
Joined 2007
Vunce said:
These are Bourns “like” trimpots.
I would be cautious using Bochen trimpots in any project, especially if using any obsolete or difficult to replace transistors.
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I bought a bunch of bourns knockoff 25 turn pots from Tayda and they seem to measure fine, but haven't put any into an amp yet. "Baoter" and "Bonens" @ something like 25 cents ea... they are cermet. I'll cross my fingers and give em a go on the next couple of channels
 
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