Current capability.
Many don't realise that the speaker demands current. It's this demand that must be net.
All of the Above, and the effects of the higher voltage, the MOSFET outputs like higher voltage and current, gets them into "the sweet spot". Also the front end is cascoded to protect the inputs from the higher voltage with the side effect of increasing the speed of the front end, which I think helps with detail and speed related distortions, but then their is always some that don't like the sound of cascading, I like the extra detail, each to his own.
Thankyou thankyou for all the info, perfect! I knew some already but that put my mind to rest. So maybe If I Make a F5 with 2 output pairs I might be happy, the turbo is a big task which I once tried and failed with, transistors were blowing up all over the place. I reworked the Turbo power supply 3 times and had problems over and over so In the end gave up.
I never used the cascode in F5t though, which may have added a degree of stability ?
Had no problems building the ACA, Zen 4, F5, and Zenlightenment
So perhaps the sound of F5 with dual outputs may sound a bit closer to the F5t ? not sure if I need 50w really although plan to use some power hungry speakers later.
I never used the cascode in F5t though, which may have added a degree of stability ?
Had no problems building the ACA, Zen 4, F5, and Zenlightenment
So perhaps the sound of F5 with dual outputs may sound a bit closer to the F5t ? not sure if I need 50w really although plan to use some power hungry speakers later.
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Interesting, when I heard the F5t I built it was built without cascode, may be why it was more likely to be unstable but anyway. Extra detail is a plus, not sure what with and without cascode should sound like
Having had a singe pair F5 with 24V rails, a dual pair F5 with 24V rails and a 32V F5T (no diodes or cascode) I can pretty confidently say the difference is mostly in bias and the change in the feedback network. Bias has a pretty dramatic effect in the "weight" of the amp. And the feedback change really mellows the amp out and has the side effect of adding gain.
I would love to have a F5T with the original feedback arrangement. Not sure if it would be stable though.
The cascode does not make the amp more stable it only reduces the voltage to the front end FETs protecting them from overvoltage condition. You could have an amp with the higher voltage for the multiple outputs and reduce the voltage before feeding the front end, though I don't know what that would do to the drive to the output. The only thing for stability on the F5T, that I see, is at what point the diodes across the output emitter resistor starts to conduct, that can burn out outputs. You could just have the emitter resistors on the outputs and would be stable but would not support the high currents of the diodes.
If the Fets were overpowered and blew could other parts then blow as a result.
I once built an F5 turbo and it kept going wrong. I rebuilt the PSU 3 times with no result.
So I'm thinking of trying again with an F5t build. With the new diyaudio boards. Last time I tried it was revision 1 of the boards which were not as good.
Just a couple of questions about F5t
If u had say 32v rails and 35v caps in my PSU. Is that too close to the caps Max rating?
If I create dual PSU then it's two transformers with 1 rectifier each?
I'm guessing this will create a better separation.
Just a couple of questions about F5t
If u had say 32v rails and 35v caps in my PSU. Is that too close to the caps Max rating?
If I create dual PSU then it's two transformers with 1 rectifier each?
I'm guessing this will create a better separation.
Rixta,
you are in the UK where we use the harmonised mains supply.
The normal range of mains supply voltage is from 216Vac to 253Vac.
Find out what secondary voltage your transformer will give when the nominal 230Vac primary has 253Vac applied.
Then you can determine what capacitors you should use.
Thanks. Don't have a transformer yet but have 8 x 35v 10.000uf caps so far.
I'm Looking for 2x 400va 24v transformer
Yes I'm in UK
OK o get what you mean. In case the mains fluctuates too high at some time it may go over the assumed 32v from 24v transformer.
I'll keep that in mind then.. Thanks Andrew
I'm Looking for 2x 400va 24v transformer
Yes I'm in UK
OK o get what you mean. In case the mains fluctuates too high at some time it may go over the assumed 32v from 24v transformer.
I'll keep that in mind then.. Thanks Andrew
I think your maximum voltage after the rectifier could be ~39Vdc from a 230:dual 24Vac 6% regulation transformer.Thanks. Don't have a transformer yet but have 8 x 35v 10.000uf caps so far.
I'm Looking for 2x 400va 24v transformer
Yes I'm in UK
OK o get what you mean. In case the mains fluctuates too high at some time it may go over the assumed 32v from 24v transformer.
I'll keep that in mind then.. Thanks Andrew
I would NOT use 35V capacitors.
Many thanks.
I now have transformer/rectifier/4x 68,000 U32d in seperate box and 8x 22,000 Kendeils in amp box.
There are a few issues relating to this build of which I am uncertain.
a, which box should house the R.
b, how much R is recommended (I have some 0.47 1%,3w dales).
c, at which position on the power supply ground, should the,
bridge/thermistor be returned to earth.
d, with respect to the above power supply, what amp rating of plug/socket should be used to connected box 1 and 2 together.
At the risk of sounding like a complete lunatic, the above build is running as well as the one described at #4991