Naimish style power amp

For the three and more legged things
richardcooper2k
Old Hand
Posts: 780
Joined: Thu Jun 07, 2007 2:32 pm
Location: sheffield

#1 Naimish style power amp

Post by richardcooper2k »

In case anyone is interested i thought i'd post about my experince with this

I'd been thinking about building one for a while as i thought it would be interesting to have something, which to my mind was at the opposite end of the spectrum to what i have (300B SET). And be able to compare in the same room with the same system. A useful reference maybe and to find out if i was missing out on anything.

I did some reading around the net (in a manlike or at least melike, obsessive fashion). What follows is what i discovered and I probably will have got some things wrong.

Until relatively recently all naim amplifiers used more or less the same circuit . The main difference is the amount of beef in the power supply. When you get up to the Nap 250 it is regulated as well (output stage included i think).

My main reference has been the acoustica website which amongst other things has stuff on tweaking naim gear
http://www.acoustica.org.uk/

There's a lot of stuff on the Pink Fish Media Forum including a project to diy build an optimised NAP style amp.

I also discovered the Avondale audio site, who do Naim upgrades, their own range of finished products and DIY modules.
Thoughts are just little stories that our brains tell us !
richardcooper2k
Old Hand
Posts: 780
Joined: Thu Jun 07, 2007 2:32 pm
Location: sheffield

#2

Post by richardcooper2k »

What i decided to do was buy a kit off ebay:
http://www.ebay.co.uk/itm/H-140-Audio-P ... 4721wt_954

It is actually most similar to the NCC200 Avondale audio circuit than an original Naim one. There are other kits on Ebay which are closer to what you find in a NAim amp. You can see the NCC200 circuit here:
http://avondaleaudio.com/power-amplifier-module-ncc200/
(click on the icon) there is some information on the circuit diagram about component choices and output inductor that proved to be very useful.
Naim schematic here:
http://www.acoustica.org.uk/t/naim/powe ... ematic.jpg

Main difference i think are the NCC200 circuit has the protection circuitry removed and some filtering between stages in the power supply.

The kit only includes amp boards and components so to be able to make a complete amp i bought a Denon amp from ebay which was being sold for spares or repair.

So i built a working amp which sounded very different to my SET but which i also liked the sound of. It lacked detail and tone but made some music bounce along in a way which i really enjoyed.

So could i "improve" the amps so they gained each others strengths or did i need two systems (or a system where i could swap power amps)?
Thoughts are just little stories that our brains tell us !
User avatar
ed
retired
Posts: 5384
Joined: Thu Jun 21, 2007 4:01 pm
Location: yorkshire
Contact:

#3

Post by ed »

brave man to let spawn of naim into your music place :)

seriously though, any chance you can try and describe the difference(s)
There's nowhere you can be that isn't where you're meant to be
User avatar
Paul Barker
Social Sevices have been notified
Posts: 8864
Joined: Mon May 21, 2007 9:42 pm

#4

Post by Paul Barker »

I don't know that I have ever heard a Naime, but I may be wrong.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
simon
Thermionic Monk Status
Posts: 5600
Joined: Thu May 24, 2007 11:22 am
Location: People's Republic of South Yorkshire

#5

Post by simon »

I found the earlier Naim stuff really aggressive - pasted against the back wall kind of thing. 10 or 15 years or so ago the stuff became much more rounded from my very narrow experience. It really grabbed hold of any rhythm in a way I've not really heard any other amps do, but had a better stab at some of the other things we like.

Haven't heard a Naim for quite a long time now, and it would be interesting to compare. £32 + power supply aint a lot to find out.

What are you using for a power supply Richard?
richardcooper2k
Old Hand
Posts: 780
Joined: Thu Jun 07, 2007 2:32 pm
Location: sheffield

#6

Post by richardcooper2k »

Simon - This amp is not forward sounding compared to my 300B amps or the power amp in a NAD 3020A.
transformer, bridge rectifier, 2 off 4700uF caps, heat sink, case, connectors, etc are all being used from the Denon donor. So it's not a high spec power supply. I have recently clip leaded in another 4 off 4700uF caps. This improved the top end with cymbals, etc appearing in the mix. Not ideal i wouldn't have thought as according to my multimeter the clipleads have measurable resistance.

Did some listening tonight to try and identify differences.
Became confused....
Started off with the SET amps in the system. Listened to a side of 33 and a third. Sounded good. Switched in Hamish the naimish amp. First reaction sounds dull, can't hear what is going on, what did i see ( or hear) in this amp. Left music on a while, while i pondered and just let the music play. Then found i didn't want to switch it off and wanted to keep listening. Why ? Realised that everything was still there but the soundstage was further back. It seemed like with the SET amp everything had hard edges but Hamish portrayed things more subtly, yet somehow the whole thing was more solid, and actually i could hear more of what was going on. (similar to Steve's recent experience with forwardness ?) Hamish's tone was a little grey in comparison but this didn't seem to get in the way of character and expression of performers.

OK, confession time ! This wasn't a fair test as the SET amps still have different drivers in the left and right channels.

Since Hamish had been working i have made some other changes which improved things but i'm tired so they'll have to wait for another day.
Thoughts are just little stories that our brains tell us !
User avatar
Paul Barker
Social Sevices have been notified
Posts: 8864
Joined: Mon May 21, 2007 9:42 pm

#7

Post by Paul Barker »

are you saying that this for £32 is better or not worse than a 300b SET amp?
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
richardcooper2k
Old Hand
Posts: 780
Joined: Thu Jun 07, 2007 2:32 pm
Location: sheffield

#8

Post by richardcooper2k »

Hi Paul

I do not want to make that judgement as i'm not sure it would be useful and might even prejudice further investigations. What will be more meaningfull to me is what i end up listening to. At the moment i like having both. Just as different people have different tastes, my own taste is not static.

I have had a couple of other reflections though:

At some point i will want to try and address the forwardness (for want of a better description of the SET amps). Having a another amp for reference (not necessarily a "better" one) to switch in and out may help me be more objective whilst doing this as i tinker. It has already helped me identify something.

The other is i wonder if Owston makes forward sounding setups sound better. The room seems to mudy things so as well as having efficient speakers and amps with headroom perhaps forwardness is helpful to sounding better in that room.
And this may not translate to what will sound best back home.
Maybe nearfield listening would be better rather than trying to drive the room although it would be difficult for us all to listen at once and would be much less fun. Not that this would put me off going of coarse.
Thoughts are just little stories that our brains tell us !
steve s
Shed dweller
Posts: 2829
Joined: Wed May 30, 2007 6:19 pm
Location: east yorks

#9

Post by steve s »

Paul Barker wrote:are you saying that this for £32 is better or not worse than a 300b SET amp?
paul i would guess richard is saying its different to his set amp..
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#10

Post by pre65 »

I'd be interested to see details of any DIY PSU suitable for these Naimish amp modules.

Preferably high quality to rival, or exceed the Naim hi-cap versions.
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
richardcooper2k
Old Hand
Posts: 780
Joined: Thu Jun 07, 2007 2:32 pm
Location: sheffield

#11

Post by richardcooper2k »

steve s wrote:
Paul Barker wrote:are you saying that this for £32 is better or not worse than a 300b SET amp?
paul i would guess richard is saying its different to his set amp..
Indeed. Not only do they have different drivers; they also have had to put up with me interfering with them. :wink:
Thoughts are just little stories that our brains tell us !
richardcooper2k
Old Hand
Posts: 780
Joined: Thu Jun 07, 2007 2:32 pm
Location: sheffield

#12

Post by richardcooper2k »

pre65 wrote:I'd be interested to see details of any DIY PSU suitable for these Naimish amp modules.

Preferably high quality to rival, or exceed the Naim hi-cap versions.
I think the naim hi-cap is for a pre-amp rather than a power amp. There is info on naim pre-amp and power supply upgrades/builds on the acoustica website.

Avondale do a power amp power supply module which consists of a bank of caps joined by inductors which schottky diodes:
http://avondaleaudio.com/cap6/

There is a project called hackernap on pink fish. Here are the details:
https://www.box.com/shared/jnasoijb2gg7mopasbuo
On this project the output stage and front end of the power amp have separate supplies. Output stage has big caps joined by 10uH inductors. Front end has smaller caps joined by resistors. Details are all in the link.

How much difference all of this will make i don't know although i will probably be doing further investigations. I doubt i'll go as far as suggested with spending on mains transformers though
Thoughts are just little stories that our brains tell us !
simon
Thermionic Monk Status
Posts: 5600
Joined: Thu May 24, 2007 11:22 am
Location: People's Republic of South Yorkshire

#13

Post by simon »

There was a Scottish guy who'd "reverse engineered" a lot of the Naim amps and had circuits for them all - must be going back over 15 years, but might be lurking somewhere on the net? Probably more likely Naim hunted them out though.
richardcooper2k
Old Hand
Posts: 780
Joined: Thu Jun 07, 2007 2:32 pm
Location: sheffield

#14

Post by richardcooper2k »

Neil McBrides site was still up last time i looked
Thoughts are just little stories that our brains tell us !
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#15

Post by pre65 »

richardcooper2k wrote:Neil McBrides site was still up last time i looked
http://www.neilmcbride.co.uk/
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
Post Reply