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Einric 9th November 2012 12:17 AM

DIY Audio F4 Premium Resistors?
Are there any resistors needed in the DIY Audio F4 clone that would be well worth the splurge on Low Noise or High Stability premium resistors?

The Space Egg Corp 9th November 2012 02:20 AM

Hi Einric

You could try some nice 'old-school' wire-wounds.
The small green 'Welwyn 22 type' 3W are quite nice.

Not realy a 'high-end, audiofool' type product...
...thus, no 'splurge' required !

Just good wire & EXELLENT stability.

You could try giving them a nice 'heat-cycle' in the oven; before matching.
Values will NEVER change after that !

Low noise...?...
...I don't think there is anything lower in noise, than a coil of wire !...
...I don't imagine you would notice any 'noise' in an F4 anyhow...
...more the territory of phono-pre's...
...but wire-wounds are 'cool' anyhow.

I like 'em anyway.



No 'bling' kudos though...
...just 'plain wire'... solid gold or platinum or unobtainium is used in the Welwyn 22's.

Einric 9th November 2012 03:06 AM

Funny thing.....Those Welwyn 3W .47Ω resistors were the ones I already had picked out.

Are any of the 1/4W resistors benefited by High Stability and better than 1% matching?

The Space Egg Corp 9th November 2012 04:17 AM

Hi Einric

I'm trying to use ALL wire-wounds EVERYWHERE !
( just a current obsession ( no pun intended ! )

Not sure about the F4 exactly, not familiar with the circuit.
I fancy a BA-3 at present with all wirewounds for the 1/4W's as well.

Using a bigger 1W metal-film, where 1/4W's go could be good ( less reactance to heat, perhaps ).

Must have a look at the F4...'s a 'follower amp' ? isn't it ?
What are you going to drive it with ?



Einric 9th November 2012 04:18 AM

1 Attachment(s)
I will be driving it with an all 6CG7 Glassware Aikido.

Einric 9th November 2012 04:20 AM

1/4W Wirewounds are pretty spendy.

The Space Egg Corp 9th November 2012 05:12 AM

Hey Einric...

N I C E !...

...She just went in my 'cool amp' folder !

Broskie has some cool designs...
...Your woodwork & caligraphy look great.

What output caps you got ?... that 'Obligato Gold' ?



The Space Egg Corp 9th November 2012 05:21 AM

Hi Einric

Sorry missed your last post.

Yeah...I see small ones at 3-4 UK each...
...but the Welwyns at 1/2 UK each.

I don't see the 'tolerance thing' as much of a deal... long as the key ones are matched per-position, per-channel... the Welwyn prices, as small 'wastage' is even OK.

Even at 5% a small batch...they come up 'good enough' on value...with a teeny bit of matching.
The series values & large ones are normaly less critical anyhow.

Only question is...will they fit the board...3W's are about 1/2" long.



PreSapian 9th November 2012 06:31 AM

how about caddock thick films?

Einric 9th November 2012 12:18 PM

Thank you for your kind words.
Yes I did use Obbligato Golds.
The design on the front actually says Ai-Ki-Do in Japanese.
I did it with a my soldering iron w/ a 1/8" tip.
I took the writing from Google Images and scaled it down to the size I wanted.
Then I taped it to the front and traced it with an X-Acto knife.
Then removed the paper and filled it in with my "wood burning" tool.

The size of these wirewounds is my main concern.
I do not know if they will fit.
I will compare my F5 boards to the online pictures of the F4 and see if there is any way of judging.
Maybe I will take the online picture and scale it to life size.
Then I can measure for fitment.


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