F5 power amplifier

[ma_coule]

I echo the words, of ma_coule, many thanks to Cviller, Peter, and www.diyaudio.com, members and diyAudio Editor's.
Especially to Mr Nelson Pass for all the wisdom and share your knowledge with the community of DIY.

Thank you very much,
jpedro

Hi jpedro,
Thank you, but kind words are from thanh1973...
Mine is only ...

 

[jpedro]

Hello ma_coule and thanh1973,

You made the correction. "Your on your own" my apologies to thanh1973. Once again thank all those involved in DIYAudio. I have learned a lot.

Best regards,
jpedro

 

[jackinnj]

Well, I am going to give lateral MOSFETs another try, I'll use the boards I have for the IRF Fet's and twist the little suckers in to fit:

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Soldered in:

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

 

[doggy]

Hello all, I have an antek ps, 400va powering my a30, this clc ps gives me 21.7 dc per channel; will this be ok for the F5 or under powered? I am thinking of swapping out my A30 boards.

 

[labjr]

Hello all, I have an antek ps, 400va powering my a30, this clc ps gives me 21.7 dc per channel; will this be ok for the F5 or under powered? I am thinking of swapping out my A30 boards.

Seems a couple volts low but should be okay. I think 400VA is enough. Which Antek are you using? The 18V?

 

[bobodioulasso]

The F5 current demand being lower than the Aleph 30 one, your rails will go higher.

 

[doggy]

Yes it is the 18vac-18vac, I was wondering why the rail voltages were lower. Are the irfp240 and 9240 not advisable?(that is what I have from an f4 parts) apparently they have some type of distortion? or ok to use? I wonder what the distortion is?

Mr. Pass said " it is not a deal breaker", but I wonder if I really want to build in a flaw for the sake of parts cost?

 

[Nelson Pass]

The IRFP9240 has higher distortion, but I have listeners who
prefer it to the Fairchild parts, so go figure.

 

[doggy]

Thanks for your observation Mr. Pass-I will use those IRFP parts then,

 

[labjr]

The F5 current demand being lower than the Aleph 30 one, your rails will go higher.

Anyone know if Antek transformers run a couple volts lower than Plitron. I was thinking of using an Antek. I want to be sure the rail voltages are high enough.

 

[RKH]

Anyone know if Antek transformers run a couple volts lower than Plitron. I was thinking of using an Antek. I want to be sure the rail voltages are high enough.

All of the Antek transformers that I have used output at the as-rated voltages. E.g. "25 VAC" gives me 25 VAC. I cannot comment on the output voltages of Plitrons.

Ryan

 

[vdi_nenna]

I have used three Antek transformers for 2 F5's and all transformers have been on target.

 

[bigfishe]

Best tranny I know of for the money

 

[vdi_nenna]

Not trying to advertise for them, but the also have nice chassis and heatsinks too. Their service is great and their right over in Jer-zee!

 

[labjr]

All of the Antek transformers that I have used output at the as-rated voltages. E.g. "25 VAC" gives me 25 VAC. I cannot comment on the output voltages of Plitrons.

Ryan

I'm more concerned about the net voltage at the power supply rails of the F5. Not what comes out of the transformer with no load. Antek makes 20 volt model which may be better if the rails come out too low with the 18 volt one.

 

[vdi_nenna]

labjr,

You will see a drop in voltage after the rectifiers and the recommended Cap-Resistor-Cap (C-R-C) filter, if you use it, which you should. It will drop a volt or so.

18 * 1.414 = 25.452, but you will lose a volt after the rectifiers. 24v after the the rect. and CRC.

20 * 1.414 = 28.28, that's too high.

Vince

 

[Zen Mod]

are we talking here about PSU loaded with A class amp , or about PSU testing , without load ?

under load - with sane VA xformer and sane C bank - you'll hardly see more than 22Vdc from 18Vac sec ......

so 1,41 is shrinking ........

 

[Horio]

Does anyone know of a good source to buy a 750VA or so transformer with 12V+12V secondaries? Seems to be a hard combination to find. I'm looking to build a pair of balanced F5 monoblocks and I want to optimize them for 3ohms prior to balancing/bridging them. The higher output rating is to allow for the option of parallel mosfets.

Thanks

 

[d to the g]

20 * 1.414 = 28.28, that's too high.

Vince

I disagree, I think the slightly higher rails sound much better.

 

[labjr]

Maybe the Plitron transformer regulates better or has a higher voltage to start. I don't know. I just want to have 24 volt rails like the real F5 because I want as much power as it will put out. Every volt matters when it's a twenty-five watt amp.