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"Better" resistors in the Naim phono stage

RichardH

RichardH

Bodging pleb
I'm messing with the Naim phono stage, and am intending to swap out some of the resistors for some "better" ones.

Looking at the schematic on Neil McB's site, I was assuming R5, R10, R16, R22 and R14 (direct signal path) should be addressed, but what about others, in particular R13? Is it necessary to replace all of these I've mentioned?

Also, I note that Audiocom are now stocking the much more affordable non magnetic Holcos as well as Vishay VSRJ. Any experience of these, particularly compared to the Welwyn RC55?
 
Vishays are cheaper from Audio Synthesis - nicer to deal with as well.

There's been a lot of stuff about resistor types on DIYAudio - might be worth a search ( I think someone called Andrew L. Weekes contributed to one of the threads on resistors)

Tim
 
The Welwyn's are ok not as good as Holco's Vihay's are better.....but you'll pay loads.

If Holco's are what you want pm me I've a few 10's of thousands so can probably find what you want.....
 
The Welwyn's have a different sound to the Holco's.

Both are good, but the Holco's have a soft sound compared to other non-magnetic options (e.g. Dale / Vishay RN types).

They are non-mag, which is good, but can be a bit soft if used exclusively, IMO.

Andy.
 
www.schuro.de do the dale cmf industrial series in small quantities and they will deal with uk. I think the cmf industrials are extremely similar to the cmf RN military spec
 
Thanks guys, is there any other good sounding resistors available in the UK? I have tried Holco's and the RC55's, the Vishay's are a bit to expensive
 
I think the cmf industrials are extremely similar to the cmf RN military spec
Click to expand...

Unfortunately the industrials are moving to magnetic end-caps, as have most resistors and sound worse for it.

The RN's are usually copper-based for leads and end-caps and are totally non-magnetic.

Andy.
 
Andy

Ref cmf resistors

Schuro website says each one they supply is tested for non-magnetism. I might email them to see if the details are a bit out of date

Tim
 
Tim,

timH wrote:

Schuro website says each one they supply is tested for non-magnetism. I might email them to see if the details are a bit out of date
Click to expand...

I do not hope so; my last invoice from Schuro (21.11.03) says clearly:

"CMF-55-143 22.1K +0,1% T9
Vishay Dale Non-Magnetic 0,25W TK25"

Any easy method to test this?

Best regards,

Oliver
 
Get one of those big red horseshoe magnets from Acme Magnet Co and see if the resistors stay where they are. Mind you it never worked on 'Road-Runner'
 
timH wrote:
Get one of those big red horseshoe magnets from Acme Magnet Co and see if the resistors stay where they are. Mind you it never worked on 'Road-Runner'
Click to expand...

*ROTFL* No such luck, no ACME product at hand. My girlfriend's diving compass is safely tucked away somewhere during the winter; my slightly magnetic screwdriver (magnetic enough to lift those bulky computer screws) did not lift them. But it was a joke anyway, wasn't it? ;)

Best regards,

Oliver

P.S. I like that ACME acronym (A Company that Makes Everything)
 
I just use a magnet to test leads / endcaps, it's not an Acme one though ;).

Most resistors are copper leads / steel endcaps, thot Schuro source looks very tempting, must compare prices.

Andy.
 
Alright then, I'll buy a test magnet tomorrow; I'll post my results in the evening. Obviously this is a tool that belongs on a DIY'ers workbench ;)

Best regards,

Oliver
 
Obviously this is a tool that belongs on a DIY'ers workbench
Click to expand...

Most definitely!

Put it into perspective though, whilst all components are better with copper leads / non-magnetic construction (it does add measurable non-linearity) as with all things it doesn't pay to assume it's the be-all and end-all.

Sometimes other things dominate, e.g. the Welwyn RC55 resistors are very good, despite the magnetic end caps.

It's icing rather than cake :)

Andy.
 
Hi everybody,

sorry for not having posted my results yesterday as promised; my 3-year-old Dell Monitor decided to kick the bucket (probably the PSU, but such things are not worth being repaired nowerdays, it seems). I had to re-animate an old Mac that had not been booted for a year. Slow, but reliable ;)

OK, I tried the Dales with my new horn tweeters, as they have a pretty strong magnet. The Dale resistors are totally unmagnetic. Just to get a positive result I also tested some Yageos, which stuck on the tweeter as if glued :)

I hope this is useful for some.

Best regards,

Oliver
 
You may like to check www.mouser.com for prices.

The RN60 (CMF60 equivalent) parts which are higher power and generally better in my view are a fraction of the price on Schuro (who only sell the cheaper CMF55).

The RN55's at 1% are even cheaper and these should fit the Naim boards (RN60's are too big).

There's no import duty on these components so you should only get clobbered for VAT in customs.

Just a thought - Mousers site is fun to navigate though...

Andy.
 
Nice one Andy - looks like an order is in order (so to speak). Presumeably you only get hit for VAT if the order is over £18. What are shipping charges like - the site is a little coy on these things.

Blimey - see what you mean re the Mouser site, though.

Just to clarify, you suggest trying:

Vishay/Dale 1/4W 1% Metal Film Resistors

Vishay/Dale 1/8W 1% Metal Film Resistors

...or is the the precision ones?
 
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