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Old 18th May 2012, 09:40 PM   #11
AndrewT is offline AndrewT  Scotland
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Each channel of an F5 draws a continuous 1.3Adc from the PSU.
That requires an absolute minimum rating for a single channel transformer of 2.6Aac.

To ensure cool running I recommend a single channel transformer rating of ~5Aac.
using 18+18Vac transformer that equates to a single channel requirement of ~180VA, two channel rating of ~360VA and 4 channel rating of ~750VA.
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Old 18th May 2012, 10:51 PM   #12
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Dimkasta.
1KVA pr ch??? on standar F5? thats a waist of money. 200VA pr ch is suficant.
i run 225VA pr ch. with 1.7A bias.
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Old 18th May 2012, 11:40 PM   #13
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Here it is 1000Va 24 v sec F5
the picture 1 is just main suply
the rest is in 2 towers with another 100 mU of caps
it sounds prety good with 2.6 A bias and is ready to go balanced
Just have to put in another 100 mU worh of caps and bolt in 2 extra boards.

Yes got head and hart hake reading Zen Mod post but he is prety decent chap
I wrote once
quote >
if it came from Zen it must be fertiliser...

Wel worth to take your time and put spaces on tha post

Can say same for same that never built a thing or heard F5
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Old 19th May 2012, 06:04 PM   #14
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My dual mono F-5 uses two Antek transformers, 300VA each....there is no reason for more. The same could be said for an even smaller one. If I recall, the commercial F-5 used a single 250VA? I may be mistaken. My current F-5 build is using a single 500VA.

Russellc
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Old 20th May 2012, 12:03 AM   #15
alazira is offline alazira  United States
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Commercial Stereo F-5 uses a single 300VA transformer. A little more will be nice (400 or 500VA) but 1K is definitely overkill. But then NP's motto is FAB so go for it.
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Old 20th May 2012, 12:09 AM   #16
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it was 1KVA pr channel
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Old 20th May 2012, 01:12 AM   #17
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Guys just a question.
Your suggestions are based on experience between 1KVA and smaller ones, or is it just that you are content with the smaller ones?

The reason why I am asking is that I see you saying that the small ones should be "sufficient" or "enough" or other adjectives that tend to describe something that is just working without problems.

Does anyone have actual experience indicating that the 1KVA has no sonic difference over for example the 300VA?

The results I have so far form my phono indicate that the difference is huge with a bigger transformer.

Please have a look at this blog entry by Richard RJM
http://www.diyaudio.com/forums/blogs...-you-need.html

You will see that the rectifier-diode/filter combination does not need current on a continuous basis, but rather in a spike-like manner. And the spikes can reach easily 10 times the nominal current draw. Which can easily be translated according to Andrew's calculations (minus the cooling compensation) to 2,6x10=26A or and for 2x18 secondaries to 18x2x26=936VA

I have tried/verified Richard's theory on my phono and there is a huge difference in the sound.

I see no reason why the bigger PSU should behave any differently. Especially with the huge filter caps that practically act like shorts
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Old 20th May 2012, 01:25 AM   #18
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I say go for big. Only thing better is dual mono with large toroid per channel. My F5T V3 will have dual 600VA. Only reason I am stopping there is because that is largest size I can get at proper voltage from Antek.
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Old 20th May 2012, 01:38 AM   #19
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i doubt you will hear any difference from a single 4-500VA and up to 2x 1KVA on F5.
and don't mind those pulses. this is what transformers are made to do.
there is no point in going for 15times transformer rating. 2-3times is just fine on a class A.
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Old 20th May 2012, 01:40 AM   #20
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Quote:
Originally Posted by buzzforb View Post
I say go for big. Only thing better is dual mono with large toroid per channel. My F5T V3 will have dual 600VA. Only reason I am stopping there is because that is largest size I can get at proper voltage from Antek.
i'm going for them for my turbo V3 too
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