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Gb: F5 Pcb

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#1,121
Got some new toys in the mail from the west coast.😀😀:mischiev:
 

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#1,122
caps

Got mine too -- real nice looking -- as usual.

Christian, you have two locations on there for a pair of power supply caps? Have you (or has anyone) tried putting caps that close to the outputs? I thought I read a while back that someone was having issues with oscillations with caps close to the outputs.

Thanks,
Steve
 
#1,126
sekess said:
Got mine too -- real nice looking -- as usual.

Christian, you have two locations on there for a pair of power supply caps? Have you (or has anyone) tried putting caps that close to the outputs? I thought I read a while back that someone was having issues with oscillations with caps close to the outputs.

Thanks,
Steve
Click to expand...

I'm happy to hear the boards are starting to arrive! 😉

The caps are marked "casc." because they are for cascoding. You can rewire them to become rail caps, but I would advice against that.

I also got a few questions about if I have more available and yes, I ordered plenty because I know from experience that a lot of people usually want to join in later when they discover the thread. 😉
 
#1,127
brucegseidner said:
I need to request some assistance and don't know if this should go elsewhere.
But, my enthusiasm frequently out distances my knowledge and judgment.

I purchased two ginormous toroidal transformers that may become boat anchors if I can't regulate them down for the F5. I imagine I can easily get by using just one for this amplifier. But I don't mind being silly and strapping the two large mains and having separate boxes for each channel. I can always use them to do some arc welding when not playing music.

What sort of regulation comes to mind and how would I wire it? Any leads would be welcome.
Click to expand...

You can use a cap multiplier to get rid of a few volts, and then you could cascode the F5 to make it run on higher rail voltages - might be too advanced, but also pretty cool. 😉
 
#1,131
Oh yeah thats right - sorry.

I'll do a guide to the changes, but I'll focus on sending out boards first, if it is ok.
Exotic parts suggestions is not my preferred hobby since I believe that most people will be able to get a better bang for the buck by getting quality standard parts and use the rest on upgrading the rest of the system or spend it on wine and music. 😉
But I can wrap up a bom for both standard F5 and the one with a few mods - no problem.
Regarding the external psu, that is a question that pops up once in a while. I think the best solution is to have the first bank in the psu box and the second bank in the amp chassis.
 
#1,134
a.wayne said:
CV,
I want to do the full board any ideas as to best place to obtain the extra cascode parts q101 and q102 , should they be matched prs also ?

Do i need the thermistors ?

regards,
Click to expand...

You can use the ztx transistors as the rest of the amp or bc550/bc560 would be perfectly fine too. For the caps, papa would recommend elna silmic. You do not need to match the transistors.
The thermistors make the amp more stable with temperature, which is good, but it is not essential to the functioning of the F5.
 
#1,136
I have just finished shipping the orders of f5, so people should get their boards soon.

a. wayne, I'll look at the parts list later, hopefully tomorrow. The cascoding is mainly for people who want to fool around with it, but I can give you an example: resistors 4.7k and 220uF caps. But you may have to fiddle around with these to get the perfect operating point.
 
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