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Upgrade NAP110

A

allen6266

pfm Member
Hi Guys,

Need your advice, I plan to change some components in my aged NAP110. As in picture below, can someone please tell is the sky blue BHC capacitors are original fitted by Naim?

IMG_3108_zpse917269f.jpg


My plan:

1. Change reservoir caps to kendeils 6800uf63v, how many pcs do I need or best, in order to match with its transfomer? 4 pcs or 6 pcs?

2. Change the tiny bridge rectifier to 36MB40A. Or any other recommendations?

3. Change the feedback cap, what is the best value? 68uf? 100uf? or stick to 47uf as fitted by Naim?

4. Change new 1k trimmers.

I do not intend to remove the protection circuits, and have already changed those old tantalum caps sometimes ago.

Thanks for your inputs.

allen
 
yes, get rid of the protection, it only protects the output transistor anyway, no good for speaker protection. Just snip the two leads, you can always solder them back in then.
 
Judging by the transformer that's a fairly early 110, if you have the serial number I can date it for you. Production ran from 1979 to 1987. Naim usually used the dark blue ITT or STC capacitors but I have seen some units with the light blue BHC ones. Any of these will have a four digit date code, yyww, where yy is the year and ww is the week. Comparing the capacitor date with the serial number date will give you a pretty good idea whether your capacitors are original or not.

What you update depends on how original you want to keep it. There is something to be said for getting a pair of BHC/Kemet ALS30A 10,000 uF 63V capacitors. The higher working voltage will help them last longer. The use of 40V capacitors when the rails can be over 39V is not recommended. The original bridge rectifier is more more than adequate for the job and having a higher rated one is not going to bring any improvement although you may like to consider one using Schottky or fast recovery diodes.

You've mentioned using 4 or 6 capacitors so you could consider using an Avondale MiniCap4 or MiniCap6. This would require the removal of the preamplifier power supply circuit and your decision would depend on whether or not you need it. I don't have the details of the MiniCap 4 to hand but the 6 comes with Kendiels and Schottky diodes killing two birds with one stone.

For the feedback cap you will get dozens of suggestions as to different types to try. If you want to stick with the tantalum beads which are an important part of getting the Naim sound I would use 47 uF or possibly 68 uF. 100 uF beads tend to be leaky and Naim got around this by fitting two 47 uF ones in parallel.

The 1k trimmers should be O.K. but replacing them won't do any harm. I sometimes fit multi-turn types even though it's easy enough to set the bias with the single turn ones.

I'd have to agree with Stuart that disabling the SOA circuit is very worthwhile, you can do this very easily by snipping or lifting one leg of each of the two diodes in the circuit.

Good luck!
 
+1 for all of what Malcom said above.
Putting those BHC (Kemet) ALS caps in is the biggest bang for buck there.
 
The serial no is 0408.

May I know which lead I have to disconnect to disable the protection circuit? Just lift diodes legs as in red circle below:

disconnect_diodes_zpsc469de64.jpg


I am more concern about the transformer size 200VA against capacitance of 6 x 6800uf caps, it will be total of 40,800uf compare to 20,000uf. And is the original bridge rectifier be able to cope with 40,800uf? I have got some kendeil caps and 36MB40A lying around here.

Thanks and appreciate you guys inputs!
 
neiljadman and martin clarks of this ilk both have worked on this

neil mcbrides page still shows up on google I think and he has all the low down

I monoblokked a pair of 110's for my briks according to neiljadman -

still have 'em
 
allen6266 said:
The serial no is 0408.

May I know which lead I have to disconnect to disable the protection circuit? Just lift diodes legs as in red circle.

I am more concern about the transformer size 200VA against capacitance of 6 x 6800uf caps, it will be total of 40,800uf compare to 20,000. And is the original bridge rectifier be able to cope with 40,800uf? I have got some kendeil caps and 36MB40A lying around here.

Thanks and appreciate you guys inputs!
Click to expand...

You need to cut one leg of each of the diodes circled, if you do it carefully you can remake the connections without removing the boards.

As to the capacitor/rectifier question I can only refer you to my previous post. The 36MB40A will bring no benefit over the existing rectifier. I'm unclear as to what you intend doing with the six 6,800 uF capacitors. If you intend just putting three in parallel on each of the two supply rails you will have gone from 10,000 uF to 20,400 uF on each rail which will probably slow down the response of the amplifier. In this instance you would be better off following my previous advice for 10,000 uF 63 V replacements. The Avondale and HackerCap boards feature inductive decoupling between the capacitors so the transformer only 'sees' the first 6,800 uF which represents a lighter load on the transformer than the original capacitors. These boards also feature better rectifiers which will enhance the performance of the amplifier.
 
I have hackercap with me, does it fit into place?
can I have the part no for the schottky'?
hope can get them from RS or farnell.

Thanks.
 
Here's a HackerCap in a mono 110:

nap110mono2.jpg


as you can see, it's a tight squeeze but there's still room for the second amplifier board. Do bear in mind that you have to lose the preamplifier power supply if you go this route.

The original HackerCap used LQA30T300 diodes (x 4) which are not stocked by Farnell or RS but you can get them from Mouser or Digi-Key. Maybe someone on here has four spares? You can also use the lower current versions down to the LQA06T300.

110 serial number 0408 was manufactured in the first half of 1980.
 
HI
I had the same choice about 18 months ago.
I phoned Les W and bought a minicap6 (about £100 I think) - brilliant and VERY easy to install, massive upgrade - though as others have noted, you will need a separate supply for your preamp (e.g HiCap). But the difference was BIG- really pleased.
If your budget is tight then the Mini Cap 4 from Les is a very good alternative (about £35 cheaper as I recall) - haven't tried it, but I've yet to hear any bad reports about Les' upgrades.
If you pm. me with your email address, Les also sent me a list of which tant's to replace and which values - I'll email it to you with instructions, pictures etc. I also have pictures of installing the minicap 6
One word of advice: DO NOT disconnect the +ve or -ve inputs to the board from the capacitor bank while the amp is or, OR turn the power on while either is disconnected - I did and blew several components!

As a final upgrade, Les may be able to let you have an AST transformer (if he's got any in stock) for this amp - again I did this and the DC voltage to the board was raised slightly from +/- 38V to +/-42V: main difference was that driving my speakers seemed effortless.

If you want to go the whole hog, go monoblock - you'll need another 110, but if you want to DIY one, you will already have the amp board, one more transformer, another minicap 4 or 6 and one of Flat's shoeboxes (available from him on ebay) and away you go.

Upgraded 110 monoblocks: STUNNING and will put a 250 into the shade.
So there you have it - one upgrade path, but you can do it in bite sized steps.

If you have a HiCap or particularly like the Naim CB look etc, the simplest and easiest upgrade for that is Les "ASR Moduue" -again a major upgrade, but really easy to do.

Good luck-Graham
 
Thanks for the info & picture. I have a diy hicap, so I do not need power supply to the pre.

I have some LQA06T300, but will I sacrifice something? is 30A vs 6A of current. But good to hear I can use them. I still hope can get something from RS who offer free shipping.

Do I need the inductor in between caps on hackercap board? can I use resistor 4R7 or 47R? CRCRC? or CLCLC?

Graham, thanks for your suggestions.
 
6A rectifier diodes will be fine for a 110, going to 30A will gain you nothing. The transformer and rectifiers charge up the capacitors which then supply the short bursts of high current required by the amplifier boards.

CRCRC for low current power supplies, CLCLC for high current power supplies. Think about it, if you use CRCRC with 47R resistors and the amplifier demands a modest 1A the circuit will try to drop 94V across the two resistors but the rail was only 39V to start with. Even two 4R7 resistors will drop 9.4V and the rail voltage will sag when you want it to remain at 39V.

Something like these inductors are fine:

http://uk.farnell.com/epcos/b82111bc22/inductor-9uh-20-6a-150mhz/dp/9752161?Ntt=9752161

Both Farnell and RS charge for shipping if the order is less than £20 but offer free shipping above that.
 
Bumping a NAP110 related thread - probably quite an elementary level question, but does upgrading the power supply unit in a NAP110 (say, to a Minicap 4 or 6) affect the gain of the amp at all?
 
eka said:
Bumping a NAP110 related thread - probably quite an elementary level question, but does upgrading the power supply unit in a NAP110 (say, to a Minicap 4 or 6) affect the gain of the amp at all?
Click to expand...

No, it doesn't alter the gain at all.
 
Another thing I was wondering (please bear with me :)) - what is the difference of the continuous power outputs of NAP110 and NAP140 based on, given that the transformers and the amp boards are exactly the same? Do the different rectifier/cap arrangements of the power supplies really affect the continuous max output (to, say, 8 or 4 ohms) so much?
 
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