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Naim Nac 12

Thanks,
I'll send you pm with serial number later on yurivv.

Great you got the phonoboards sorted Jeam, very engaging and bouncy with vinyl through the Nac12 - enjoy.
 
HiCap-powered sounds right - not 'OTT' at all! :) I'm sure a SuperCap would make your 12s-5 sound even better! :D

Andy

Ha! I would need at least 2 Supercaps - one on each rail:eek:

I will see what gives once the answers roll in.

Cheers,
Peter
 
The Nac 12 after a quick clean. Also i transfered a voulme pot from another example. Some difference in sound between the 12/3s, but not much. Very enjoyable - Get Rythm,-
I have ordered a blue alps 20k. Do I wire the leads the same place as on the original pot?

IMG_2350.jpg


cards121.jpg
 
Can anyone suggest a simple way to reduce the overall gain on a NAC12S driving a NAP 120?

My setup is in a small room and I have Videoton Minimax speakers and am quite close to the speakers. The volume control is nearly always between 8 o'clock and 10 o'clock!

I have and attenuated lead for the CD but even on the LP12 the volume control is too sensitive.
 
Can anyone suggest a simple way to reduce the overall gain on a NAC12S driving a NAP 120?

My setup is in a small room and I have Videoton Minimax speakers and am quite close to the speakers. The volume control is nearly always between 8 o'clock and 10 o'clock!

I have and attenuated lead for the CD but even on the LP12 the volume control is too sensitive.

There is such a mod - and I read about it here. Neil McBride is the name of the guy who posted it; he has a website.

Or, buy the Ryan Sound Labs replacement daughter-boards ... these have (I think) 3 different gains that you can set using jumpers. They are also supposed to sound considerably better than the Naim boards - I can't confirm this yet, though, as I have bought the boards but haven't yet installed them.


Regards,

Andy
 
Output board gain can be altered by changing the amount of feedback, which is set by the value of two resistors. As standard the values are R9=1K and R14=12K, which sets the gain at 13 (R9 + R14 / R9). This translates to 1V output for 75mV input. To change the gain you need only change the value of R14. Changing R14 to 5.6K halves the gain.

Gain_board_schem.jpg


Mr Tibbs
 
There is such a mod - and I read about it here. Neil McBride is the name of the guy who posted it; he has a website.

Or, buy the Ryan Sound Labs replacement daughter-boards ... these have (I think) 3 different gains that you can set using jumpers. They are also supposed to sound considerably better than the Naim boards - I can't confirm this yet, though, as I have bought the boards but haven't yet installed them.


Regards,

Andy
Ryan Sound Labs probably out of my budget but thanks for the suggestions.
 
Mr Tibbs

Thanks again. Just got myself some 5.6k resistors that helps a lot. Gives me a couple of extra "hours" on the volume control.
 
Output board gain can be altered by changing the amount of feedback, which is set by the value of two resistors. As standard the values are R9=1K and R14=12K, which sets the gain at 13 (R9 + R14 / R9). This translates to 1V output for 75mV input. To change the gain you need only change the value of R14. Changing R14 to 5.6K halves the gain.

Mr Tibbs

Thanks for the tip. :) OK, changing R14 from the stock 12K to 5K6 halves the gain ... does this produce more feedback (to go with the lower gain) ... or less feedback?


Thanks,

Andy
 
Thanks for the tip. :) OK, changing R14 from the stock 12K to 5K6 halves the gain ... does this produce more feedback (to go with the lower gain) ... or less feedback?


Thanks,

Andy

Yes; feedback doubled = gain halved.

Side benefit of increasing feedback is improved performance (measurably lower distortion and flatter frequency response).

Pitfall of increasing feedback is greater risk of instability so don't be tempted to go too far. Interestingly the schematic above shows an extra cap (C6) added across the base/collector of TR5 and this has the effect of improving stability.

cctaylor - glad that worked for you.

Mr Tibbs
 
Yes; feedback doubled = gain halved.

Side benefit of increasing feedback is improved performance (measurably lower distortion and flatter frequency response).

Pitfall of increasing feedback is greater risk of instability so don't be tempted to go too far.

Mr Tibbs

Thanks, Mr T. :) But another pitfall of increased feedback (associated with lower distortion) might well be a change in the harmonic profile to reduce H2/H3 and increase H5 and above? Which will tend to make the sound harsher.


Andy
 
Thanks, Mr T. :) But another pitfall of increased feedback (associated with lower distortion) might well be a change in the harmonic profile to reduce H2/H3 and increase H5 and above? Which will tend to make the sound harsher.


Andy

We're talking going from very low THD to lower still. Highly unlikely there would be any difference subjectively.

Mr Tibbs
 
We're talking going from very low THD to lower still. Highly unlikely there would be any difference subjectively.

Mr Tibbs

On the surface - yes. But I suggest the only way to decide this is to listen to both - ie. a 12s with stock gain vs. a 12s with half the gain, through R14 halving.

IME, an amp which has, say, 0.01% THD ... 99% of which is H2 - will sound better than an amp which has 0.001% THD ... 99% of which is H5 and above. IOW, it's not the absolute level of THD which makes an amp sound good - it's its harmonic profile.


Regards,

Andy
 
I transplanted Siemens caps from the 111 phono boards to the amplification and buffer boards to replace the Samwha caps in the Nac12/2 (see post 111) I think the unit sound better with the Siemens caps - even more enganging and natural, also it's nice to have it in original condition.
The phono cards are 322/1.

IMG_2462.jpg
 
I still use a serviced Nac 12S in original condition, right now with a recapped Nap 120. The latter is superb, a fantastic power amplifier.
A 12/2 which resides here now came with an instruction leaflet. It seems that Mr Vereker recommended Technics turntables at some point.

nac12%20instr.jpg~original
 
I still use a serviced Nac 12S in original condition, right now with a recapped Nap 120. The latter is superb, a fantastic power amplifier.

What do you mean by "fantastic", Svein? Compared to other Naim amps ... or to amps in general?

Where I'm coming from is that about 15 years ago, I took one of my 250s over to the home of the guy behind AKSA amps ... to compare against his 'AKSA 55', which was about the same power into 4 ohms. The AKSA completely demolished the 250 - so I bought 2x AKSA 55s and an AKSA 100 for my 3-way active Maggies and sold my 2x 250s and 1x 160.

If I rate the AKSA 55 as 4/10, the Naim 250 would have been 2/10 ... so my opinion of the sound of Nail amps is low. :D And since then I have gone through 3 AKSA amp upgrades so that I'm currently sitting at 8/10 (compared to the original AKSA 55 rating).

Andy
 
Hi andyr. I am sure your AKSA ampilfiers are very good. The 250 is not my favorite amplifier either. The BD 160 is better. I am a bit crazy about Naim from the 'Salt Lane days' and think this gear perform in a way that I really like. The midband in particular sounds very direct, rythmic really enganging. I was in doubt about mentioning the 120 because the intention was to share the Nac 12N leaflet. Yes, I think the Nap 120 is a good amplifier by any standards. In addition to the dynamic rythm and drive it's also melodic.
 


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