F5 Turbo Builders Thread

Marra · 2013-03-13 12:20 pm

I was listening to some vinyl last night through the cascoded V2 when my daughter happened to walk in; she sat down for a listen and said "it has such deph" followed a short while later by "its like being there!"
I could'nt agree more I think its a keeper.I'm listening with P3 in mid position;once I'm used to the amp I will have to experiment.
I think I asked once before would there be any benefit to using four output's and lowering the bias? Its currently running at 320mv with the sinks a cosy 45C.

Marra · 2013-03-13 12:28 pm

A couple of pics.

The power supply before I wired in the umbilical.

The amp on top of p/s.

buzzforb · 2013-03-13 12:51 pm

Yes. I think there is another advantage that I am unsure of. One reason Nelson used the diodes was to reduce drop across Rs and increase the available current from the fets. By using more fets, you get more current capability by default and each fet has to contribute less to the total demand. This is speculation, but i wonder. Other benefits are higher DF and lower temps inside the individual fets, making it easier to maintain a specific temp.

PKI · 2013-03-13 1:40 pm

I am busy this weekend, but will be playing with different numbers of outputs next week. If you wait, I will post about my experience. Here the picture of my amp(I really like this concept of chassis

buzzforb · 2013-03-13 2:31 pm

too small, but goes well with surrounding.

Marra · 2013-03-13 4:38 pm

Thanks Buzz I think I'll run it as is for a while and maybe double up some time later in the year.I must say I'm liking what I hear this amp is so in control;not that the standard F5 was'nt; but the V2 is just so authoratative and I'm sure Im hearing stuff that I was'nt previously.

buzzforb · 2013-03-13 5:55 pm

Don't have to convince me. Dual mono helps out as well in terms of low end, clarity, and blacker background. Best thing in the world is to just stop and enjoy.

valvesound · 2013-03-14 7:30 am

PKI said:
I am busy this weekend, but will be playing with different numbers of outputs next week. If you wait, I will post about my experience. Here the picture of my amp(I really like this concept of chassis

PKI - (1) what value caps are you using?
(2) what voltages are you running on the secondaries?

BTW I like your layout, it makes it very simple and clean to transplant to the case eventually.

Marra · 2013-03-14 8:47 am

buzzforb said:
Don't have to convince me. Dual mono helps out as well in terms of low end, clarity, and blacker background. Best thing in the world is to just stop and enjoy.

Thats exactly what I intend to do.I've hardly turned the amp off the past couple of days.
A big thanks to Nelson;Teabag for the pcb's and yourself for the matched Fairchilds and cascoding transistors. :cheers:

PKI · 2013-03-14 12:49 pm

Valvesound, they are 100k uf @50V each. Secondaries are 25V. Thanks

valvesound · 2013-03-14 2:03 pm

PKI said:
Valvesound, they are 100k uf @50V each. Secondaries are 25V. Thanks

0.1F each WOW! 0.4F / channel not a cheap supply. I was thinking with going for 47000uF each...do you think that's to small?

PKI · 2013-03-14 2:10 pm

valvesound said:
0.1F each WOW! 0.4F / channel not a cheap supply. I was thinking with going for 47000uF each...do you think that's to small?

Not a super expensive either, check digikey

Even with halve of this reservoir I had a very good sounding amp. Now it is just a bit better

AudioSan · 2013-03-14 2:38 pm

wow. 400.000uF pr ch? i hope you have heavu duty transformers

PKI · 2013-03-14 3:00 pm

I hope so too

))

Good thing about it: I turn it off and have time read the forum and fall a sleep still listening ;-)

AudioSan · 2013-03-14 3:48 pm

i would use around 1000VA+ transformers for that amount

or a slow charge. it is hard for transformers to charge those caps. i tryed 408.000uF with 1000VA transformer. everything was vibrating when i started it up

PKI · 2013-03-14 4:36 pm

With two thermistors everything looks good. just a small vibration for less than a sec

. But I like this thrill feeling of powering up my gear and feel the power

.

AudioSan · 2013-03-14 4:51 pm

PKI said:
With two thermistors everything looks good. just a small vibration for less than a sec . But I like this thrill feeling of powering up my gear and feel the power .

hehe

i know the feeling

i guess those thermistors are on the mains(softstart). and around a sec sounds about right

PKI · 2013-03-14 5:23 pm

I'd say that soft start helps. Maybe I'm wrong though.

AudioSan · 2013-03-14 5:30 pm

well. that only helps the main fuse and the transformer. but it does nothing with the charging current to the caps. and that is hard for the transformer.
AndrewT may have a recipe for this one.

PKI · 2013-03-14 6:39 pm

AudioSan said:
well. that only helps the main fuse and the transformer. but it does nothing with the charging current to the caps. and that is hard for the transformer.
AndrewT may have a recipe for this one.

I am not so sure about this, but I am not an engineer, so maybe some parts in the picture I have in my head will cancel out and everything will be as you say

F5 Turbo Builders Thread

Member

Member

Member

Member

Member

Member

Member

Member

Member

Member

Member

Member

Member

Member

Member

Member

Member

Member

Member

Member