F5 Turbo Builders Thread

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Marra

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Joined 2009
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This morning I powered up the front end and adjusted the voltages across R5/6;fortunately no issues doing so.As I am running with +- 38V dc I am only getting 11.3V at the jfets[cascoded] Is there an optimum voltage for the jfets as 11.3 seems a bit low. I thought that if I parraled a second 10k resistor;having used Audiosan's formula on the bom I would then have about 16V;would this be better? Tia.
 
Nikitas

Nikitas

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Joined 2011
I've been waiting for those for months. I got responses "in 2-3 weeks will be ready" when I asked, but those weeks lasted months. Looks like the cad designer disappeared - at least untill the day I was waiting - . Go for tea-bags, their all-in-one and of spectacular quality. Only better option I see, is to etch your own.
 
oiphy

oiphy

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Joined 2011
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buzzforb. or anyone else for that matter. please keep the English simple :)

what are the pro and cons of high or low rail voltage.
I'm using same teabag boards as you, fully populated.
yet to decide cooling but might go exotic :)
yet to decide trafo
my caps are several 100v 47000 so.....
any toughs??

ps building 4 boards so stereo mono ... so on ...
 
buzzforb

buzzforb

Member
Joined 2010
Higher rail voltaage means more power into higher ohmic load. For instance, for 100w into an 8 hom load, you will need about 40-42V rails. For a 4 ohm load, you will need only 32v rails. Large impedance loads need more voltage swing. Low impedance loads need more current capacity If you are wanting higher than 100W into 8 ohm load, then you really need to consider balanced(bridged) topology, as this doubles the power into double the load. For example, an amp that can do 50W into a 4 ohm load will be able to do 100W into an 8ohm load if using a balanced(bridged) topology.

A consideration that is often overlooked is heat. Even if you can dissipate a lot of heat, the fet is still generating a lot of heat,internally, before your cooling system takes it away, so life expectancy becomes an issue.

What is your speakers setup?
 
oiphy

oiphy

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Joined 2011
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Blink_PT

Blink_PT

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Joined 2007
audiopt.net
buzzforb said:
What I am saying is that the natural draw of the bias of the amps will drain the caps pretty quickly with out any bleeder.
Click to expand...

I realized, this PSU does not need the resistances of bleeding, because when connecting the channels themselves dissipate the tension, correct?

Today I did a test PSU will, turned on a 2 toroidal 12V without connecting channels, and capacitors were with 17V rail on each, still have stored ...
 
I

ijscobar

Banned
Joined 2012
I'm planning on building a F5T also. Same as TC-Goh
http://www.diyaudio.com/forums/pass...-your-diy-pass-amplifier-153.html#post3334011


I thinking about using 4 of these in the powersupply
ALC10C333EF035 - BHC COMPONENTS - CAPACITOR, 33000UF, 35V | Farnell Nederland
and make a possibility to choose between CRC and CLC. Transformer will be a 2x24V 625VA or 800VA.
The combination of 4x 33.000 uF and transformer will be used for 2 channels. I'm planning on building 2 stereo amps for either bi amping or maybe bridging.

Question: will this power supply be enough?
 
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