F5 power amplifier

I will most certainly be auditioning a pair of 1990 MG2.6/R's on a F5.

Rated for 87dB sensitivity and 4.7 ohms, I cannot imagine the ribbons will disappoint with an F5, I hear the top-end is supernatural on the F5 - that is also how I could describe those foil ribbons - what a match!

I hope so. I have a pair of them and am just starting to build an F5 for dedicated use on the foil ribbons. Bypassing the passive crossovers was the first step. And I still have trouble believing how big a difference that made. The F5 looks to me like a really good choice for the ribbons. At least I am going to find out. Crossover point is about 750 Hz and impedance is aprox. 3.2 ohms. And they are far more efficient than the bass panel. If this works out as well as I hope it does, then I will have to find the complimentary amplifier for the bass panels. Which I don't want to think about yet. But those are a whole different animal. I suspect that will ask for maybe 200 Watts into 4 Ohms to get all of the goodness out of those. Perhaps less now that the passive crossover isn't taking its tax on the supplied power.
 
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Like this maybe
 

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Hi,

I make layout for my F5 board, please help me to check this layout, assuring there is no faulty on it. I havent edit the SK370 layout, the correct one is reverse it. Also about the thermistor, its better if placed near output transistor.

Thanks before
 

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F5firstwatt.jpg


i am wondering, there is +24 -24 and Gnd after CRC, the picture shown above don't connect anything to Gnd after crc, is it no need to connect the Gnd from crc to the Gnd of F5 board??

here is mine.
An externally hosted image should be here but it was not working when we last tested it.



i have a bunch of stupid questions, hope you all don't mind

my transformer used is E transformer which lead out 18 0 0 18, in before i am too stupid to connect both 0 0 together and into the Gnd of the CRC, and smoke coming out from the wires :O so end up i don't connect anything to both 0. Or is it wrong anything?
 
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Psu (CRC) ground is connected to F5 board.(Green wire)
Generally, the outputs of a transformer are 0-18-0-18 and not 18-0-0-18.
To check, connect the two presumed 0 together and then measure voltage across the two 18. You should read 36v. As long as you do not short a winding, there is no risk.
 
post7766.
are the two double insulated wires coming from the transformer, the mains input?
If yes, then they should be double insulated all the way back to the mains fuse and to the IEC input socket.

Twist all the wire pairs into and out of the transformer to minimise the radiated fields.
 
chchyong89;
On mine the F5 ground goes to speaker negative and input negative only, CRC ground goes to chassis earth, 18 0 to 1 rectifier and the other 18 0 to other rectifier with the 2 positive outs of rectifier joined together to CRC + and same with - from rectifier, hope that makes sense.

i am using the example shown by
An externally hosted image should be here but it was not working when we last tested it.


i connect both 18Vac into one rectifier, which the 0 where to go is still a question😕