Definitive Build

[Daniel Quinn]

I've been doing diy for 4 years . I started because i'm stubborn [ 1 arm Isn't going to stop me], I was suddenly poorer and I needed something to do.

I'm not a natural diyer , if it hadnt been for the brain bleed I would have been content with NVA. Though Richards death and real world prices mean it was much less attractive.

Ive made about 37 amps. All solid state and all with the same power supply.( transformer, bridge and caps) The only thing that differed was the size of transformer, caps and the amp boards. I've now settled on the amp boards . fm300 £120 from China. Its well made , as minimal components and even fewer capacitors. .

time as come to do my definitive build. Which is why im seeking the collective advise of audio talk. They are to made of acrylic as thier predessors were in tribute to richard.

is it worthwhile shielding the transformer?
the best connection wire?
size of transformer and capacitors
any modifications to power supply?
are connectors made of copper or' audiophile' materials a waste of money

And anything anybody as learnt whilst building their own amps and now would'nt build an amp without it

[pre65]

Sometimes a picture, or diagram is of use.

Try doing a sketch of your power supply, with component values, then we can comment.

[Nick]

My 2d

"is it worthwhile shielding the transformer?"
No, but I would think about getting some from toroidy.pl I have found them to be much better made than ones from RS or Rapid in the sizes that you will be using.

"the best connection wire?"
Thick enough copper for the current. twin code and earth is a good source of solid core.

"size of transformer and capacitors"
For a 100w amp, I would consider 300w-400w. Maybe > 50000 uF per side. Try and use low ESR types, preferably longer life. Also experiment with 1uf film bipass on them as well. Some amps like them some dont.

"any modifications to power supply?"
Without knowing what you are building its hard to say. I would suggest using two bridges and two secondaries, one for each rail. Works better with asymmetric loads.

"are connectors made of copper or' audiophile' materials a waste of money"
There are some good value solid but not too expensive connectors from CMC that I like. Depends on how much you value bling and how often you intend to plug/unplug.

[ed]

is it the naim circuit that fm300 refers to?
if so, are you sure you're paying the right price for the board?

just thought I'd mention it because there are loads of fm300 ready built for much less than the figure you mentioned....one thing I have learned since moving to Yorkshire is to keep my hand in my pocket for as long as possible....

[Daniel Quinn]

sorry partial info!

there are no photos as it hasnt been built and i dont understand circuit diagrams.

ive got two 650va with two 30v secondries vigortronix transformers. ive never had any noise problems as i cover them in contact glue and i cannot tell the differences in terms of sound.

i currently use 1 bridge for plus and negative rails and 33,000 caps in tandem

never seen the board anywhere else and it is populated as i cant do fine soldering.

its not a naim circuit , but ive got loads of them.

[Daniel Quinn]

Not worked !

[Nick]

I have edited it for you. It needed to be a link to the site not an image. Just using the link lets the forum software try and do the right thing.

[Daniel Quinn]

Thanks . It shows the power amps I built from scratch. The pre amp and phono amp I built with nva boxes and the Lenco tt I built

[Paul Barker]

Sometimes a picture, or diagram is of use.

Try doing a sketch of your power supply, with component values, then we can comment.

with one hand and that not very good?

[pre65]

Sometimes a picture, or diagram is of use.

Try doing a sketch of your power supply, with component values, then we can comment.

with one hand and that not very good?

If Dennis can build and modify amps and turntables with one hand I'd think a simple diagram was well within his capabilities ?

[Paul Barker]

It sounds like youre power transformer is right power. Nick’s post to you on these things is on the money. Paul Mcgowan of psAudio said something similar about power supplies. It goes something like Paul Mcgowan speaking not me “ We tried a bigger power transformer and it sounded better, so we tried an even bigger one, and that sounded better too, so we tried another one bigger than that, it too sounded better.”

What I find lets the Chinese down so far is their scrimping on power supplies. Ive stripped a few chinese amps down to the components and there is nothing in them I could use, theyre built so weak and stretched. They never use centre tapped high tension windings so all the world are building hybrid rectifiers, compromise 1 right there. Then the core is saturation because onbody told the Chinese our voltage never was never has been 230v, and now were out of Europe, the lie we told when we pretended to harmonise with Europe, was simply a form filling excercise and we carried on the same. So cores are too small for our voltages. So yes as Nick and Paul Mcgowan say, you go bigger and the bigger you dare go you will be rewarded.

Of course psaudio are well known in the diy community for their power conditioners, which were all the talk 20 years ago, but all talk like that is a bit silent key these days. But power conditioning is a worthwhile thing imho. I am opposite of you I dont know the Late Richard or have any interest or knowledge in his past circuits, and there wont be any more. Im only interested in valve amps and the ways of building them that did for them in their day. So I wont comment on hook up wire caps or resistors or connectors interconnects or power chords. But I fancy those are less significant than power supply, though theyre used in it!

[Paul Barker]

Sometimes a picture, or diagram is of use.

Try doing a sketch of your power supply, with component values, then we can comment.

with one hand and that not very good?

If Dennis can build and modify amps and turntables with one hand I'd think a simple diagram was well within his capabilities ?

youre obviously not an ex nurse.

[pre65]

with one hand and that not very good?

If Dennis can build and modify amps and turntables with one hand I'd think a simple diagram was well within his capabilities ?

youre obviously not an ex nurse.

No Paul, I am not.

I think the reason Dennis was against diagrams was his lack of knowledge on the symbols used to indicate electrical components, but I could be wrong.

*

[Nick]

because onbody told the Chinese our voltage never was never has been 230v, and now were out of Europe,

Our mains is and was perfectly in line with the EU specification. Its just they never built to the spec. CE required handling 220v to 255v. That in its self is a problem as without regulation that means heater supplies are from maybe 6v to 7v. Of course getting a primary tapping switch is hard now so even if the primary had the old 100-110-120-220-230-240-250 taps it would be a problem to make it available.

[Daniel Quinn]

Is there any theoretical advantage of using 4 33,000uf capacitors per channel on my monoblock power supply instead of 2 .

And how do I wire them up?