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NAP 90 versus NAP 160

There is an alternative. Have you listened to stuff outside the Naim stable? If you have and you don't like it then well and good, carry on. However if you haven't there is a possibility that you don't actually like the Naim sound.

These Naim upgrade threasds seem often to have a common theme -
Question - I've upgraded but I don't like it.
Standard answer #1 - You need to service it, it must be faulty.
Standard answer #2 - If this doesn't work, junk all your non-Naim kit or buy more expensive Naim gear. (Implication: No other brands will possibly work.)

You wouldn't accept this kind of advice re a car or any other household equipment, so why would you on a hifi?
 
Listening to stuff outside the Naim circle isn't the issue. Everyone knows the 160 is a far better amp than the 90 and it will easily better the 90 in all the areas the OP mentioned. That makes you think there's something wrong with it so the replies have been about getting it sorted. We all know there's life outside of the "Naim circle" - just that non of it's better that's all pmsl.
 
The other possibility is that someone has been tinkering with it and all is not as it should be... another reason to get it serviced by an authorized dealer like Class A.
 
amp2.jpg






Pics as requested. Anything dastardly here? I can't see any leaks or anything. The wiring all looks good to my eyes.

I know I like the Naim sound. I'm very close to the getting the sound I want.

In an ideal world, I'd have bought a fully serviced as-new amp.
And in an ideal world, I would still be employed :)

So, as funds are scarce, I shall be going the DIY route as Jon tells me it's dead easy and he's been kind enough to give me a list of the parts I need.

If the power all goes off in your houses next week, you'll know I've started.
 
hollamby said:
Pics as requested. Anything dastardly here? I can't see any leaks or anything. The wiring all looks good to my eyes.

I know I like the Naim sound. I'm very close to the getting the sound I want.

In an ideal world, I'd have bought a fully serviced as-new amp.
And in an ideal world, I would still be employed :)

So, as funds are scarce, I shall be going the DIY route as Jon tells me it's dead easy and he's been kind enough to give me a list of the parts I need.

If the power all goes off in your houses next week, you'll know I've started.
Click to expand...

Looks quite a bit different to the 160 I owned but then yours is older. I wouldn't recognise it versus mine so you need someone who has knowledge of the bolt-up type.

Nothing looks to be leaking to me but if you've got a list of parts to replace and it's economical enough then you may as well try it. Look out for a 32.5 though, is my advice.
 
The capacitors all look original but there's a sign that someone's been inside before. If you look where the wires (black and red) come into the amplifier board section you'll see marks where a soldering iron has come into contact with the wiring. I doubt that Naim would ever have left them like that.

A couple of the nuts holding the amp boards are rusty, but that's not a major problem.

I'm sure that Jon has given you very good advice but, for what it's worth and bearing in mind your need to keep expense to the minimum:

Replace the two large blue 10,000 uF, 40V capacitors.

As you have a CD 3 I'm assuming that your FlatCap is running your NAC92. If so you don't need the pre-amp supply in the 160 so don't bother upgrading it. So there's no need to change the smaller 3,300 uF blue capacitor, nor the two red tantalum beads on the PAPS1 board (that's the tiny board on the centre divider). To isolate the pre-amp supply completely unsolder the two orange wires coming from the transformer to the small bridge rectifier on top of the 3,300 uF cap. Isolate and insulate them.

Replace the three red tantalum beads closest to the input end of each amplifier board on a like-for-like basis using good types such as Kemet or AVX. The values of these vary from amplifier to amplifier in the Naim range. The input coupling one is almost certainly 10 uF, 35V the other two probably 47 uF but they could be higher.

The other two red tantalum beads on each board are part of the SOA circuitry which should be disabled to give a good sonic improvement. There are several ways to do this but the easiest is to snip or lift one leg of each of the two diodes just below the two red beads. On one board they are blue and black and on the other they are multicoloured. Alternatively you could remove the two small transistors beside those diodes. Either of these methods will disable the unwanted part of the circuit and save you replacing those four beads into the bargain.

Whilst the boards are out replace the rusty mounting hardware with stainless steel parts.

With no speakers or input connected check the bias on each board and re-set if necessary. Check that the d.c. offset on each channel is <30 mV or so. Bob's your father's brother.

Total parts buy: 2 x 10,000 uF, 40V capacitors, 6 x tantalum beads (values depending on what is already fitted), nuts and bolts. That's got to be less than £35.

malcolm
 
misterc6 said:
The capacitors all look original but there's a sign that someone's been inside before. If you look where the wires (black and red) come into the amplifier board section you'll see marks where a soldering iron has come into contact with the wiring. I doubt that Naim would ever have left them like that.

A couple of the nuts holding the amp boards are rusty, but that's not a major problem.

I'm sure that Jon has given you very good advice but, for what it's worth and bearing in mind your need to keep expense to the minimum:

Replace the two large blue 10,000 uF, 40V capacitors.

As you have a CD 3 I'm assuming that your FlatCap is running your NAC92. If so you don't need the pre-amp supply in the 160 so don't bother upgrading it. So there's no need to change the smaller 3,300 uF blue capacitor, nor the two red tantalum beads on the PAPS1 board (that's the tiny board on the centre divider). To isolate the pre-amp supply completely unsolder the two orange wires coming from the transformer to the small bridge rectifier on top of the 3,300 uF cap. Isolate and insulate them.

Replace the three red tantalum beads closest to the input end of each amplifier board on a like-for-like basis using good types such as Kemet or AVX. The values of these vary from amplifier to amplifier in the Naim range. The input coupling one is almost certainly 10 uF, 35V the other two probably 47 uF but they could be higher.

The other two red tantalum beads on each board are part of the SOA circuitry which should be disabled to give a good sonic improvement. There are several ways to do this but the easiest is to snip or lift one leg of each of the two diodes just below the two red beads. On one board they are blue and black and on the other they are multicoloured. Alternatively you could remove the two small transistors beside those diodes. Either of these methods will disable the unwanted part of the circuit and save you replacing those four beads into the bargain.

Whilst the boards are out replace the rusty mounting hardware with stainless steel parts.

With no speakers or input connected check the bias on each board and re-set if necessary. Check that the d.c. offset on each channel is <30 mV or so. Bob's your father's brother.

Total parts buy: 2 x 10,000 uF, 40V capacitors, 6 x tantalum beads (values depending on what is already fitted), nuts and bolts. That's got to be less than £35.

malcolm
Click to expand...

Malcolm

Thanks for that, but knowing Kim as I do, that'll have scared the sh1t out of him!

Clearly someone had been messing around with this amp, as this thread shows, but I didn't notice the soldering iron burns of which you write.

Kim, I'm happy to replace the caps for you, and can check the DC offset with my DMM. I think we can leave the pre-amp PS in situ as, since it's unused because you have the FlatCap, I don't think it'll do any harm...

Bet you wish your flight hadn't been cancelled!
 
Malcom, many thanks for taking the time to write all that lot. Much appreciated.

I am definitely scared now.
 
Well it's a very early 160 - witness the blue caps (probably branded "Erie" or "ITT") Having replaced these in my NAP250 and similar caps in my multitude of Meridians I can tell you that leaking or not they are sh*gged out and need to be replaced before they go completely. I think I can see a slight bulge in the vent cap of the right one ----indicating it's on its way out. And when they go bad this happens

I'm not sure if the bridge rectifier is original - all bolt together 250s/160s I have seen previously have had 4 axial diodes mounted through the wall,. Though it looks to be more than adequate for the task in hand and in line with Naim's later units but could probably be bettered with some fast recovery diodes.

The amp boards have obviously been worked on at some point and repairs made - it looks like in isolation to the bad channel. The 1N4148s are different on the two boards as are 2 or 3 of the resistors. While it probably doesn't make much difference it would be my preference to make parallel changes on both boards to make sure everything stays in balance. But the red tants all look to be original - which my mean the all need replacing for best performance. You'll probably find that 3 of them are 10uF/35v and two are 47uF/6.3v

And since it has been worked on some output devices may have been changed - pop the covers of the 4 transistors on the back panel and make sure they all match. They should probably all be BDY58s for this period.
 
Johnny Blue? Goodness me , the cavalry's arrived.

You're right, I am scared. Turn the football off and prepare for a big week.
 
Don't mention the f-word. Did you see the results yesterday? I'm still in mourning.

Follow Malcom's and Neil's advice and see what those caps are, and then order some replacements. I want some stuff some from Farnells, so don't order anything until I can piggy-back my order onto yours (or, better still, vice versa and I'll add the caps to my existing order).

Thanks to one and all for the guidance: much appreciated.
 
Sorry. that wasn't my intention. I hoped, rather, to save you buying more than was absolutely necessary for your use.

To both yourself and Johnny Blue - I'd still recommend disconnecting the input to the pre-amp supply from the transformer. Even if you are not drawing any current from it there is still a danger of the elderly capacitor leaking and you'd not be aware that was happening. This could easily be reversed later if you wished.

Let me know how it goes,

malcolm
 
Good advice from Neil above.

The square bridge rectifier here is a new one on me as well but I thought that it was original as there is no sign of the four holes for the individual diodes. I would also have recommended the fitting of better rectifier diodes but was mindful of the need to keep the cost down.

The caps are almost certainly ITT at this vintage.

I've seen both those types of 1N4148s in 160s but never mixed in the one amplifier.

Please let us know which power transistors are fitted as Neil suggested.

malcolm
 
I'd agree with Malcolm, just disconnect the smaller blue cap and remove it if you are not going to use the supply.

The big caps are 15,000uF/63v and if buying from Farnell I'd probably go with the BHCs...and consider upping them to 22,000uF
 
All the 160s I've seen have 10,000 uF 40V fitted and I would caution against going up to 22,000 uF. There have been other threads on here where undesirable effects have been noticed from going that high. There's no problem going to a higher voltage rating though especially as improvements in the technology has shrunk the size of electrolytics over the last 40 years.

Here's an album with photos of two 160s (I've 'borrowed' some of these shots from CJ1045, hope he doesn't mind for this exercise):

http://picasaweb.google.com/misterc6mg/NAP160?feat=directlink

The first picture shows a pair of ITT 10,000/40 in place in a 160 and looking pretty original. The second is of an identical ITT that I removed from a NAP110. The third shows a different 160 with a pair of 10,000 uF Erie caps that look like replacements to me.

These from Farnell should do the job:

http://uk.farnell.com/jsp/search/productdetail.jsp?sku=1572893

although Kendeil do a 10,000/63 but the only source I can find for these is eBay Italy,

malcolm
 
Sorry about that - my extruded case 160 definitely had 15,000uFs in it as did my BT 250s in it I just assumed that the BT160 did too.
 
No problem Neil. I might have advised going from 10,000 to 15,000 uF but not to 22,000 uF although there's something to be said for replacing like for like with vintage Naim stuff.

malcolm

p.s. I think I'm correct in saying that there's quite a bit more space in the CB (extruded) case compared with the bolt down.
 
Have you seen the size of modern caps , like for like they are a lot smaller in some cases , I've used 22,000uf caps in place of 15,000 and they were 80mm long as opposed to 105mm of the 15000 that were removed.
 
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