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Naim 323 'K' boards Q's

The Captain

The Captain

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Hi chaps,

sorry if this is an old hat of a subject- but having just acquired a pair of MC 323/3 K boards it's dawning on me afterwards, that it's a bit tricky to consider it's output/ choice of carts which match. I had thought there was just 322 for MM's, & 323 for MC's. Then I read about the K/S/E.. urgh. Ballache for me to understand: arm & cart "micro information" I find daunting & often difficult to comprehend.

Ok I think I'm right that these K 323's, were designed 'for Linn' carts? If so, why is this? I suppose it might be something to do with output matching (so it think that's mV?) , &/or loading value (which I believe is simply a resistor value).

So am I tethered in choice to only Linn mc carts then? Or if not, am I looking for a particular 'range' of matching criteria values in another brand of MC cart to suit these K boards?

If only it was as simple as 322 MM's: one type/ bung em in/ buy a MM cart (even high output MC's work) & you're done.

Thanks, Capt
 
323K's were specifically designed for the Linn Karma (hence the K). The 323S was designed to work with earlier Linn cartridges.

My experience is that they certainly need the loading components altered and sometimes also the gain for optimum use with other MC cartridges. Fortunately this is very easy to do for the loading since it just involves changing one resistor and possibly one capacitor (thought actually the capacitor often makes very little difference).

Gain is a bit more involved.

What cartridge are you looking to use?
 
colasblue said:
323K's were specifically designed for the Linn Karma (hence the K). The 323S was designed to work with earlier Linn cartridges.

My experience is that they certainly need the loading components altered and sometimes also the gain for optimum use with other MC cartridges. Fortunately this is very easy to do for the loading since it just involves changing one resistor and possibly one capacitor (thought actually the capacitor often makes very little difference).

Gain is a bit more involved.

What cartridge are you looking to use?
Click to expand...

Hi cola,

thanks that's a fab summing up for me. In fact I had just now found Neil McBride's page with a bigger explanation- but your post is an ideal boiled down few lines for me!

Well I haven't yet got a cart. The idea being that I scour the classifieds for an old 323 pair, bag em, then I can proceed to explore MC carts. I totally forgot about MC board variations, & gain/ matching xyz. So I just bought these 323/3 K's.

I did once try 323's (I think likely 323/2 'S' boards.. but can't rememeber) with a DL 103. Ten years ago. Sniffed at the sound being too hard, or bright or something. But was probably too hasty in retrospect.

Ten years on & a bit more knowledgeable about changing one cap value in my current MM (322) boards, to suit a cart.. by attenuating the treble.. I am thinking to dip a toe back into MC. A second wind as it were.

So I can easily change the input resistor &/ or the input cap, to perhaps do that treble attenuation 'tailoring' thing this time: great: realtively simple then. But it's the gain aspect then though- I see a thread of a pfm'er who comlained his dynavector 20 cart, with 323 K's, was much lower on the preamp vol dial. This would drive me nuts. So in his case, what could be done to up the gain?

Thanks indeed, Capt
 
Upping the gain a bit is just a resistor change which is fully explained on the McBride site but I've never tried more than doubling it. Lowering the gain for things like Lyra and newer Ortofon is a bit more involved. There's a thread in DIY where I optimised the gain and loading for a Kontrapunkt b with a bit of help from Malcolm. Ended up with a board somewhere between K and E in terms of gain. The big issue with some of the newer "low" output MC's is that the output isn't low enough for Naim boards and you get an audible headroom issue.
 
@colasblue So in the example of the dynavector chap, whose preamp vol knob was unusually high it seemed to him, the idea there would've been to UP the gain on the MC boards? Have I got this thinking the correct way round?

I'm not quite following the "audible headroom issue" phrase you see.. as your eg there seems opposite to my imagining things, as I imagine this phrase to mean the vol dial is ( like the dynavector chap), up unusually high.. meaning the unwanted introduction of audible noise.

If the vol knob was unusually low, I can't see how there would be any "audible issue", as there wouldn't be any introduction of anything unwanted (would there?).

Thanks, Capt
 
Ahoy @The Captain,

In @colasblue's absence, I'll attempt to shed some light (hopefully in line with what he was saying).
The Captain said:
@colasblue So in the example of the dynavector chap, whose preamp vol knob was unusually high it seemed to him, the idea there would've been to UP the gain on the MC boards? Have I got this thinking the correct way round?
Click to expand...
Yes, as this would get the cartridge signal up relative to the noise floor of the electronics. IOW, having the volume knob far higher than usual will only better reveal that there exists worse signal to noise than is possible. Basically, there need be a balance between input sensitivity and gain. Those cartridges that fall foul of this balance, either too high or too low in output level, are more likely to not sound at their best.
The Captain said:
I'm not quite following the "audible headroom issue" phrase you see.. as your eg there seems opposite to my imagining things, as I imagine this phrase to mean the vol dial is ( like the dynavector chap), up unusually high.. meaning the unwanted introduction of audible noise.
Click to expand...
I think the confusion here has to do with colasblue also describing the opposite scenario where many modern MCs have higher output than some phono inputs are capable of dealing with. Think amplifier clipping where the signal is so high that the peaks end up being clipped off. Back when I were in retail, HOMC were a new thing and there were more than a few punters who seemed to think that these performed best into LOMC inputs (rather than into MM as intended). It wasn't much of a surprise to moi that many of these customers were also heavily into heavy metal rock. (insert head banger emoji here)
 
@Craig B I was actually hoping your ship might come to my stranded self, & impart your wisdom!

Great those two scenarios you kindly outline make things clear.

You see as I see it/ in my observation, that although I read many opinions saying "Meh, who cares if your naim vol knob is right up at 4 o'clock, instead of 12 o'clock.. so what?" what I hear being introduced as I turn up the vol knob, even with nothing playing, is a gradual increace in noise. Hiss. Every amp does it. Turn VOL up to 4pm even with nothing playing, & it's a significant ammount (let alone I'm not too comfortable with it up so high on it's rotation just because).

So to my thinking, a 'standard output' MC cart with the "correct" gain on the 323 boards, for example, meaning I have my vol dial at my typical 12 o'clock listening vol knob position (eg matching my MM cart via my 322 boards too- which is what I hope to achieve once I choose a MC cartridge)... would be less noisy, than if my gain on my 323 MC boards were to be lower (&/ or my MC cart's output were to be lower) meaning my vol knob would need to be ramped up to 4pm.

This is chiefly why I want to achieve you see, a " 12 o'clock parity" on the vol knob, with what I'm used to with my MM carts: well near as dammit 12.. a tad of variation maybe, say 12:30pm one MM might have been.
 
The important bit from McBride site:

'Moving Coil NA323 Phono Board...
A few component changes were made over the years, with slight layout changes. The modern Mark 5 boards have a few changes; R2=4K3, R3=100K, R17=200K, R14=82K. The loading is done by R1 and C9. The one shown is the S type i.e. 470R, 6n8. The K type is 560R, 1n0.

Note that the gain can easily be adjusted (I've tried changing it by a factor 2 with no problem) by changing out R13 (220R). For example putting in a 110R in its place will double the gain, which may be useful if you are trying to match the subjective output from LP and line inputs'
If you change R13 to 110ohm you really need to up the feedback cap to at least 100uF, otherwise you really will begin to roll the bottom end off.
 
@a.palfreyman that's fantastic info, many thanks!

You know what, I was going to go on to ask whether or not it's a simple enough job to affect the gain, by altering a resistor or two on these 323's. Fab. So that answers my Q.

I can safely then buy a LOMC without worrying too much if sounds 'low on the VOL dial'.

I would tho prefer not to have to change out the 47roe feedback, if I could: I'm that convinced these feedback maroons are so important/ fundamental for the naim sound. I've never seen a 100/40v type, rare as hens teef I'd bet.
 
Aha thanks @a.palfreyman I didn't think these existed. Might I have to buy 10x minimum though.. hmm.

I just hope I can stay with the original though, & only small resistor tweaks needed.

If I have an MC in mind, when I stumble upon one, maybe I can get some thoughts on what the tweaks would likely be.. before I buy it: if it were to cost say an extra £25 just to change this cap, I'd have to choose another cart.
 
Not sure of the overall gain TBH.
I have (but haven't used in ages) an ATOC9 MLII into diy stage based on NA323 circuit. ATOC9 MLII specs at 0.35mV so decent for MC and I found I had to double the output (by above resistor mod) to get near CD level. I'll have a look what I used for FB caps...
The issue is that 110ohm and 47uF puts the corner frequency (roll-off) at 30Hz which is quite high...
 
323 cards have modest snr, upping the gain or actually using the full range of the pre amp, I'd go for the latter
 
@a.palfreyman I'd be interested in what MC cart you and anyone used into these 323's.. indeed. That would be very useful info.

"Matching to cd level" is a good phrase for what I mean. My 322 MM's are just one small notch lower on my stepped vol pot (so almost as loud/ a good match/ fine), as my cd player.

So with these K boards in standard configuration, am I looking for a particular "range of output numbers", with the MC cart, in order to make them similarly loud as my MM boards?

As you can tell I'm a real newbie re. MC carts. Thanks, Capt
 
a.palfreyman said:
According to this:
NA323 has 26dB more gain ie 20x that of the NA322.
What cart gives you a close match on the 322 cards @The Captain?
Click to expand...

Hey great vintage naim bumf there.. never seen those, my 32-5 etc.

I'm using a Shelter 201 mm. Which was a pinch less on my dial than a Linn k5 stop gap cart.

So if my cdp were at Vol dial 12 pm (straight up).. my best MM equivalent so far in terms of output, is this Shelter at Vol dial 1:15 pm (& k5 @ 1:45pm ish). If that makes any sense to you.

Ideally I just tweak the loading resistor in these 323's, were I to find my Vol @say 3pm with whatever cart I stumble upon, to get me to my 1:15pm aim point. Anything more complicated I'm a bit reticent about, as 4 of those 100uf ROE's = £20 you see.

I wonder if anyone might have an mc that's end of life, that I could just get a brief taster with (& return it back for example): this would be a very useful idea. Mainly the output but even get a semblence of the sound too. Summat like apthe typical charlies DL304 or 103, At33 or OC whatnots. No idea if such old dead ones lurk unused but I believe not worth anything being single use stylus's.

Thanks for the help 'freyman.
 
Shelter is 4mV and K9 is 4.5mV nominal output.
OC9 MLII is 0.35mV nominal output so should be nearer 12 o'clock on the dial with the 323 cards.
 
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