Member
Joined 2009
Paid Member
Since I felt started here I searched for the mag - and found it quickly.
So let me quote Julian Vereker from Hifi+ Issue4 (Dec1999), talking about the NAP250:
"... In the very early years, the actual transistor types did vary, but the planar type Motorola pre-drivers and the Ferranti drivers are still the same as those we used in '74. The input pair hasn't changed either, and these have been very closely matched, because this is where the feedback meets the signal. There are no circuit configuration changes of any sort.
The power transistors changed too in the early years, basically what I really wanted simply wasn't available. The early Solitrons were, quite frankly, too fragile, and things got better first with the BDY56s, and then the BDY58s. Iwanted a transistor which was very fast (rather than necessarily linear), without any staorage time especially at low currents, and I wanted it to turn off at low currents...."
I do not know if Paul Messenger has mixed up things here a bit.
On the same page:
"... Big transfomers and the diode switching spikes are a real devil to control - but you need them to make the thing work. Sure you can go and put a capacitor across them and the spikes will go away, but so will the music too! ..."
So let me quote Julian Vereker from Hifi+ Issue4 (Dec1999), talking about the NAP250:
"... In the very early years, the actual transistor types did vary, but the planar type Motorola pre-drivers and the Ferranti drivers are still the same as those we used in '74. The input pair hasn't changed either, and these have been very closely matched, because this is where the feedback meets the signal. There are no circuit configuration changes of any sort.
The power transistors changed too in the early years, basically what I really wanted simply wasn't available. The early Solitrons were, quite frankly, too fragile, and things got better first with the BDY56s, and then the BDY58s. Iwanted a transistor which was very fast (rather than necessarily linear), without any staorage time especially at low currents, and I wanted it to turn off at low currents...."
I do not know if Paul Messenger has mixed up things here a bit.
On the same page:
"... Big transfomers and the diode switching spikes are a real devil to control - but you need them to make the thing work. Sure you can go and put a capacitor across them and the spikes will go away, but so will the music too! ..."
Member
Joined 2009
Paid Member
Interesting !
In terms of power supply, I've read similar comments from Hugh Dean regarding the AKSA amplifier. There is a goldilocks amount of capacitance that produces the sound the designer is seeking.
I'm not surprised about JV's interest in the absence of minority charge carrier storage given that the quasi-comp output is susceptible to cross-conduction because of it.
In terms of power supply, I've read similar comments from Hugh Dean regarding the AKSA amplifier. There is a goldilocks amount of capacitance that produces the sound the designer is seeking.
I'm not surprised about JV's interest in the absence of minority charge carrier storage given that the quasi-comp output is susceptible to cross-conduction because of it.
Member
Joined 2009
Paid Member
WOW ! - that seems to me to be a rare find. I've not seen anything about the NAP 120 and certainly none of those detailed photographs.
Read what the owner had to say about it: "What a great amplifier. Funky and dynamic with great transients and superb timing, which make it sound accurate and controlled as well. It plays with enthusiasm and never give up regardsless and can sound sweet, but also fierce when needed - impressive."
As links are wont to stop working I've uploaded the images here
Note - there are no Zetex E-line transistors, all TO-92 cans. I found a comment on the Naim forum that the NAP 120 was derived from the NAP 160 (JV's favourite?).
A very simple power supply, common rail caps for both channels and they look only to be 1,000F per cap. I think the EI transformer helps (only used in early versions, later changed to a toroid) as they tend to block mains-borne hash better than toroidal transformers from what I've read (it all depends on the windings...).
Whose to say I shouldn't just go with option a), the simple single-rectifier for both channels and be done with it. It seems nobody complains too much about the NAP 120!
Read what the owner had to say about it: "What a great amplifier. Funky and dynamic with great transients and superb timing, which make it sound accurate and controlled as well. It plays with enthusiasm and never give up regardsless and can sound sweet, but also fierce when needed - impressive."
As links are wont to stop working I've uploaded the images here
Note - there are no Zetex E-line transistors, all TO-92 cans. I found a comment on the Naim forum that the NAP 120 was derived from the NAP 160 (JV's favourite?).
A very simple power supply, common rail caps for both channels and they look only to be 1,000F per cap. I think the EI transformer helps (only used in early versions, later changed to a toroid) as they tend to block mains-borne hash better than toroidal transformers from what I've read (it all depends on the windings...).
Whose to say I shouldn't just go with option a), the simple single-rectifier for both channels and be done with it. It seems nobody complains too much about the NAP 120!
Attachments
Last edited:
Ah , my first work on Naim gear was with one of those NAP120s. I recall the difficulty and long delay obtaining the correct electrolytics and surprise at the E-I transformer. Local enthusiasts didn't rate the 120 very high on the scale of Naim models. Perhaps this was just prejudice because some examples here were manufactured under license in New Zealand, not only Salisbury, in those times when high tarriffs were used to restrict imports. Surprised? 
Nelson Pass said the same thing - the charging pulses need to be slow. Capacitors charge near the peak voltage which is a relatively small time period in an a.c. cycle. Fast rectifiers switch abruptly and charge in a shorter time. If the switching time base is reduced the height of the spike will be greater to deliver the same energy.
Member
Joined 2009
Paid Member
Since we quote JV, I'd like to say that I respect the man, but he wasn't the designer of the Naim circuit.
I see him more like the Steve Jobs of audio. He knew what he wanted and he had the vision how to do it. He was interesting person no doubt. Charming maybe. He had good taste for sound and interests in mechanics, but I wouldn't take everything that he says in interviews and blogs as indisputable truth. I have a long text file with his posts, and I have read several magazine interviews. IMO, parallel to some valuable info, he was also a big contributor to some of the "snake oil" in hi-end.
Use with caution
I see him more like the Steve Jobs of audio. He knew what he wanted and he had the vision how to do it. He was interesting person no doubt. Charming maybe. He had good taste for sound and interests in mechanics, but I wouldn't take everything that he says in interviews and blogs as indisputable truth. I have a long text file with his posts, and I have read several magazine interviews. IMO, parallel to some valuable info, he was also a big contributor to some of the "snake oil" in hi-end.
Use with caution
This has to do with capacitor charging rate and diode resistance which increases if the rectifer has to pass more current. So there is a question in terms of peak current whether it is better to have 2 diodes or 1 conducting on a half cycle - for efficiency 2 will have less resistance and charge the capacitor more rapidly - or to defy convention and take another approach as in the NAP250 which is not the present focus.
Well said. I guess much of JV's practical talent for audio was limited to the tweaking of existing ones. That much can't be denied because it's what critically identifies the products as different (and very successfully so) from the basic application note designs they were. The rest, including PCB design, pretty wiring, power supplies, dated component types etc. was always spin and obfuscation, as you would expect from any entrepreneur or spokesman for a high-end manufacturer, unwilling to consider change to a successful formula.
You have to admit that he made some astute, brave choices and creatively articulated claims over many years with the same black boxes and add-ons. We still celebrate the basic, original sound quality despite the product's otherwise forgettable features and for the most of us, still unaffordable prices.
Much of what JV commented on was picked up and used by the British Hi -Fi press in the glory days of subjective assessment when a load of new descriptions came into fashion. This helped the British Hi-Fi industry then under threat of being over-run by Japanese manufacturers. Had that happened it would have decimated the British Hi-Fi press.
It is easy to look back and criticise - but this needs to be seen in the context of the time. It happened and the world learned and moved on.
It is easy to look back and criticise - but this needs to be seen in the context of the time. It happened and the world learned and moved on.
Member
Joined 2009
Paid Member
Absolutely ! - even here, today in this forum, people become fascinated by audio because of the mixture of engineering and art, the objective and subjective, the real and the imaginary. If we all talked about Kirchoff and poles and zero's it would be dry, I never would have been interested in the hobby in the first place. It can be fun to read through the writings of the pioneers who actually made a decent living at this stuff, not the cheapo stuff on eBay.
One thing I try to be careful about is bringing forward all of the opinions from the past when based on technology that has changed a lot since then, making some of the findings of old unsuitable for basing decisions on today.
Naim now have designers who wear white lab coats for press photographs
One thing I try to be careful about is bringing forward all of the opinions from the past when based on technology that has changed a lot since then, making some of the findings of old unsuitable for basing decisions on today.
Naim now have designers who wear white lab coats for press photographs
Last edited:
Naim now have designers who wear white lab coats for press photographs
Maybe that is why the modern Naim amps still sound good, but the older ones had much more mojo and character!
As far as I know JV never claimed to be the creator of the basic circuit, since it is a simple application from the 70s. But he changed it in several significant details until the sound was up to his expectations. You may call that tweaking, but I call it ingenious!
I remember that somebody in the envious press "found out" that the basic Naim circuit was just an application from RCA. He then claimed loudly that the amp was crap, because of that.
What do we learn from that: (Audio-)journalists are just humble humans (or sometimes plain stupid) and the spirit always is in the details.
I remember that somebody in the envious press "found out" that the basic Naim circuit was just an application from RCA. He then claimed loudly that the amp was crap, because of that.
What do we learn from that: (Audio-)journalists are just humble humans (or sometimes plain stupid) and the spirit always is in the details.
Well, let's also try to remember that it is the source music that is the art we should be getting all romantic about.
The electronics is engineering. Characterizing engineering problems as being nebulous and ethereal and open to artistic interpretation is the road to crap electronics. This characterization often works well for people trying to sell crap, tho.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.