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NJ321 and 729 resistors

C

Colin Barron

pfm Member
Which resistors are best. Avondale use Welwyn Ultra precision bulk metal film resistors 4812 and 4804 series. Another suggestion was holco, another charcroft Z foil (very expensive). In the 321 notes the implication is that only R1 R2 and R2a matter so does that mean only use quality ones here and anything will do for everything else. Holco are only 25p so using this better quality for the other positions will not break the bank.
 
You could try the Dale 55D or 60D series. Some are available on ebay, or through Mouser.
 
I use Welwyn RC55Ys for all the signal path resistors and Welwyn MFR4s for all the others. All easily obtainable from Farnell.

malcolm
 
I guess it depends on the application... MRS25 metal films are cheap but good. Ideal for regulator circuits, etc.

I agree with chiily about the Dales. The RN55, RN60 etc sound pretty good in the signal path and are cheap enough, too. I used them in my Starfish. Mouser has loads. For feedback resistors in my fish and monoblocks I just stuck to the tried-and-tested Welwyn RC55Y, and they sound fine. Any better than an MRS25 or RN55? No idea. Haven't even tried!
 
hacker said:
I guess it depends on the application... MRS25 metal films are cheap but good. Ideal for regulator circuits, etc.

I agree with chiily about the Dales. The RN55, RN60 etc sound pretty good in the signal path and are cheap enough, too. I used them in my Starfish. Mouser has loads. For feedback resistors in my fish and monoblocks I just stuck to the tried-and-tested Welwyn RC55Y, and they sound fine. Any better than an MRS25 or RN55? No idea. Haven't even tried!
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I've yet to put RN55s in my Starfish. I should really get around to that. I have them in the 323's transistor ladder (@15R) and they were certainly an improvement in noise terms over Naim's orginal cardons.

I think the consensous is that the RN55/60 are a little more 'round' sounding, with the Welwyn RC55Y's a little more 'direct'.

You could try both.
 
I use the Charcroft in my B1 on the outputs, I can't say they sounded any better than the RC55's they replaced.
 
These cards have relatively small pin holes and a lot of the spacing is pretty tight, so be careful to not over-size the resistors. I found PRPs, in particular, to be a pain on these cards.
 
These cards have relatively small pin holes and a lot of the spacing is pretty tight, so be careful to not over-size the resistors. I found PRPs, in particular, to be a pain on these cards.
Bearing this in mind would you recommend 1/4 watt for all sizes.
Would Welwyn RC55Ys 1/4 watt work ok in all positions (most comment they are the optimum price performance).
 
colin Barron said:
These cards have relatively small pin holes and a lot of the spacing is pretty tight, so be careful to not over-size the resistors. I found PRPs, in particular, to be a pain on these cards.
Bearing this in mind would you recommend 1/4 watt for all sizes.
Would Welwyn RC55Ys 1/4 watt work ok in all positions (most comment they are the optimum price performance).
Click to expand...

Yes, but there is no point in the extra expense apart from the ones in the direct signal/feedback paths. If you don't know which those are I'll put up a list tomorrow. As I said before MFR4 (0.5W) are perfectly fine everywhere else.

malcolm
 
Which resistors carry signal in the NJ boards - 321 and 729 circuits?

I experimented with various values for R15 the output resistor and in the end I went back to the Naim (32.5/72) standard 22K as opposed to the 100K of the 82 circuit, in fact a Welwyn RC55Y 22.1K that gave better tone and detail to standard resistors. Perhaps that O/P resistance value better matches older Naim power amps like my 160.

I wonder if it's worth changing R10 back to the 32/72 standard, I think 1K, though it sounds fine as is. What purpose does that have?
 
Colin Barron said:
Which resistors are best. Avondale use Welwyn Ultra precision bulk metal film resistors 4812 and 4804 series. Another suggestion was holco, another charcroft Z foil (very expensive). In the 321 notes the implication is that only R1 R2 and R2a matter so does that mean only use quality ones here and anything will do for everything else. Holco are only 25p so using this better quality for the other positions will not break the bank.
Click to expand...

We have tried countless series of resistors Colin, from the most basic cheap 1/4 carbons to the charcroft z foils. Our experience is that the best are indeed expensive. In the signal path, consider using Welwyn MFR, RC55Y, AMRG or bulk foils. The latter couple will give excellent results but the bulk foils are in a league of their own, we have tried time and again to find better and they are simply the best you can get, extremely costly though.
 
Not much between them as long as they are metal film.
Brands don't count as much as measuring the resistors and matching values for left and right channels.

Upgrading from metal film to metal foil is worthwhile for phonostage though.
 
Could anyone help identify the signal path resistors in the 321/729 , i.e. NJ321/729 boards, by listing the R numbers? Thanks.
 
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