DIY Audio F4 Premium Resistors?

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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.

Cheers.

Si.

No 'bling' kudos though...
...just 'plain wire'...
...no solid gold or platinum or unobtainium is used in the Welwyn 22's.
 
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...
...it's a 'follower amp' ? isn't it ?
What are you going to drive it with ?

Cheers

Si.
 
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I will be driving it with an all 6CG7 Glassware Aikido.
 

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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...
...as long as the key ones are matched per-position, per-channel...
...at the Welwyn prices, as small 'wastage' is even OK.

Even at 5% tolerance...in 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.

Cheers

Si.
 
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Si,
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.

Thanks,
Richard
 
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For the precision wirewound resistors I was looking at these Vishay MR106's for the 100Ω, 1kΩ & 10kΩ.
They are large at 1/4"x1/2" so there would only be a few that would even fit.
The 100Ω resistor looks like it's right at the 240 & 9240's, that is probably the only place where these would fit.
Are these high precision wirewound resistors really any better that a well matched metal film?
 
Hi Einric

There is of course nothing wrong with the 'vertical-mounting' of longer parts.

I don't think it's 'high-precision' we're talking about really.
The 5% Welwyns, actualy come out pretty darn close to stated value.
Matching, per position & per channel, isn't that hard...
...tiny bit of wastage maybe...
...but seeing as an F4 doesn't need a bucket-load of resistors anyhow, not TOO expensive.

I would buy 6 of the Welwyns; as opossed to 1 'precision' any day.

I think the issue of 'noise' here, is pretty much a 'non-issue'...
...in a phono-stage, yes...an F4 ? Mmmm...well not nearly so...by a country-mile.

I think the issue of Metal-Film Vs. Wire-Wound...
...is more one of 'subjective-tone' , or something like that !
( audiophile-adjectives, NOT a speciality ! )

Why does a valve 'sound' different to a transistor ?...
...or does it even ?
You should know, with your cool line-stage.

I think it all depends on the application...
( I just happen to be WW obsessed at present...
...maybe I'll get over it...
...maybe I won't...
...maybe they'll nail me in a pine-box, with all my de-soldered WW's ! )

Cheers

Si.

Einric...
...There's no such thing as WIN, WIN, WIN !

( we can try though !!! )
 
Thanks Einric

I assumed for some reason, they were probably 'coupling caps'.

But seems not.
HT power-supply bypass instead.

I have the circuit schematic somewhere on the computer.
What are the 'red-Wima's' used for in the Broskie ?

I think, by the way, a valve 'front-end' (sort of) is a great move for a tranny amp.

What you listen to most Einric ?
CD, LP, tape, etc. etc.
Rock, Blues, Jazz, Classical, etc. etc.

Just wondered...

Cheers

Si.
 
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