Yes, I recall that previous search then and finding the similarity was just not there. Funny, I had also looked some years earlier and found, IIRC, another RCA design which I saw as having strong similarity to the NAPA. Perhaps I've just confused it with another search but that design, as Nigel Pearson put it, was like nothing he could remember.
Not really. The RCA is rather better in some ways ( See Harmon Kardon Citation for a better match if memory is correct ) . It is like saying A Honda is an MV Agusta motorcycle. In the simplest way yes it is. I think this idea was put out by people who copied Naim in the early days. I wrote to Alan Morington West about this (as near as he will say he designed it , he wasn't pleased to be asked ). He is not unlike the D Self we all read. He said that the design was original in a way that convinced me. The design I suspect comes from the 741 op amp if anywhere ( also Sinclair Z30 of 1969 ). An idea who's time had come. The old Quad valve design hints at the same and the Rogers Cadet. Radford being the really interesting version of pentode plus triode in long tail pair. Early transistor amps for cheapness took a backwards step, the devices cost a fortune. Before anyone says, the valve amps only have a passing similarity. The idea of note being from Alan Blumlein circa 1934. His long tail pair input. Gorge Gogny somewhere between 1964 to 67 was using the idea. In some small ways RCA might have copied him. I rather like the feedback he used. HC Lin was using this idea in 1960 when the op amp was classified. It is highly strange no one did what we now take as standard. It was possible in 1957 and even furthur back. The NAP160 output stage is HC Lin of 1957 plus a Baxendale diode for better balance. Mr Self objects to the suggestion of saying modified Lin for the modern designs. Perhaps someone somewhere sees that Lin almost certainly was the first to use it in op amps. Mr S infers the writers do not see that the feedback route is very different in the 1957 amp. However the 1957 is the better example of how to apply feedback and the Gogny maintains that whilst having a Naim like input.
The 22K and 1 K long tail pair resistors are so wildly wrong as to be a choice. I had the spectrum of the NAP 160 of early vintage. It was almost perfect if following the ideas of Jean Hiraga. That is if the distortion falls exponetially harmonic to harmonic the ear will hear much less distortion. This seems to be true. Very distorted valve amps that follow this rule sound very clean. Equally the Quad 303 sounds very similar. The difference is the two distortion curves are 40 dB apart. To most peoples ears both are very low distortion. The reasons for this in medical research are well known. It is just the shape of the inner ear that sets a reference. If the amplifer distortion is not unlike the ear all is good. The ear hitS 30 % at times. If you balance the Naim input you will have a sound more like a Denon PMA 250. Both are excellent. A current mirror to replace the 22K and 1 K would work ( BCV 62 if memeory correct ). The stability capacitor might need to be increased to regain stability as slewing has improved ( > 56 pF ) . Personally I would keep the 22K + 1K. It raises the second harmonic to give warmth and give correct harmonic balance. I have always suspected the NAP160 was a rejected Quad design that was to replace 303. 405 was promoted instead. All the Naim amps of old love Quad speakers. The sound is so much better than a typical Naim sound as to make me think the NAP160 was super tuned to that speaker. Even the Nait 2 works. Naims are not noted for the depth of sound stage. With the Quads it is vast.
I have said much of this before. Seemed time to say it again. Naim, Like HD motorcycles. What is "so bad" about them is why people like them.
I think D Self uses 22R for current mirror balancing. BCV 62 would be OK with that. Self isn't quite right about mirrors. The Vce is important and his intended results do not seem real world. To get rid of second harmonic distortion is not a typical Naim sound. If BCV 62 you could try a double mirror and no resistors. Fig 3, 4 transistors.
Current-Output Circuit Techniques Add Versatility to Your Analog Toolbox
Current-Output Circuit Techniques Add Versatility to Your Analog Toolbox
If one uses a single transistor without any degeneration resistor for the second stage, or VAS/TIS, then one only has ~600mVbe available across the load from the first stage.
If that load is a resistor, then it's easy to determine the load current and thus the first stage current.
When you replace that collector load resistor with a CCS, or mirror, the CCS also sees the same ~600mVbe.
If one adds a degeneration resistor to the CCS/mirror, then one runs into saturation of the CCS, i.e. it does not works as a good CCS/mirror. The bigger the volts drop across the degeneration resistor the worse this saturation problem becomes.
Now change to the added EF in front of the VAS/TIS. This is the arrangement in the Blameless and adopted by many since.
One has ~1200mVbe as the voltage across the input collector load.
Now you can add in the degeneration resistors to the mirror.
Some, including D.Self, use very low volts drops across the degeneration resistor attached to the CCS/mirror.
Other recommend upto 600mVdrop across the degeneration. But remember this ONLY works when there is adequate voltage to avoid saturation in the CCS/mirror.
If that load is a resistor, then it's easy to determine the load current and thus the first stage current.
When you replace that collector load resistor with a CCS, or mirror, the CCS also sees the same ~600mVbe.
If one adds a degeneration resistor to the CCS/mirror, then one runs into saturation of the CCS, i.e. it does not works as a good CCS/mirror. The bigger the volts drop across the degeneration resistor the worse this saturation problem becomes.
Now change to the added EF in front of the VAS/TIS. This is the arrangement in the Blameless and adopted by many since.
One has ~1200mVbe as the voltage across the input collector load.
Now you can add in the degeneration resistors to the mirror.
Some, including D.Self, use very low volts drops across the degeneration resistor attached to the CCS/mirror.
Other recommend upto 600mVdrop across the degeneration. But remember this ONLY works when there is adequate voltage to avoid saturation in the CCS/mirror.
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rensli, I can't see why you would try to use a balanced LTP when the original is clearly intended to be unbalanced to ensure the 2nd harmonic distortion is prominent.
You'll wind up with a low-grade generic design by using a current mirror in the input stage of a Naim and whilst it will probably sound more clear and sharp, it won't be as pleasant to listen to. Both approaches to good sound quality have their merits but I think it would be better to simply build a chipamp amplifier if you want good results with that mirror arrangement in a Quasi-complementary design.
With tweaking experience, you can do better with discrete designs but it takes good skills with basic electronic design and hundreds of hours testing and listening to learn what it takes to get decent, "musical" sound quality from a particular design. You can't learn that from forum posts, so be prepared to study formally and do a lot of empirical experimentation for yourself.
I see your note about the dominant pole capacitor (100pF in your schematic) being there to prevent destruction. I guess that could be the case if it was too small but 100 pF is a heavy amount, depending on the capacitance (Cob) of the actual VAS transistor used. If you overcompensate, the sound quality becomes awful, rather quickly. So it pays to get this value matched to the VAS and its current source transistor. That's why you only need 39pF if the original ZTX653/753 pair are used. See the values on the NCC200 schematic posted recently.
You'll wind up with a low-grade generic design by using a current mirror in the input stage of a Naim and whilst it will probably sound more clear and sharp, it won't be as pleasant to listen to. Both approaches to good sound quality have their merits but I think it would be better to simply build a chipamp amplifier if you want good results with that mirror arrangement in a Quasi-complementary design.
With tweaking experience, you can do better with discrete designs but it takes good skills with basic electronic design and hundreds of hours testing and listening to learn what it takes to get decent, "musical" sound quality from a particular design. You can't learn that from forum posts, so be prepared to study formally and do a lot of empirical experimentation for yourself.
I see your note about the dominant pole capacitor (100pF in your schematic) being there to prevent destruction. I guess that could be the case if it was too small but 100 pF is a heavy amount, depending on the capacitance (Cob) of the actual VAS transistor used. If you overcompensate, the sound quality becomes awful, rather quickly. So it pays to get this value matched to the VAS and its current source transistor. That's why you only need 39pF if the original ZTX653/753 pair are used. See the values on the NCC200 schematic posted recently.
Both Andrew and Ian make strong points. I was fogetting that the input current is a bit less than modern designs.
One thing you could try is a very small resistor in the VAS emitter. When I did this for a friend we used 47R and 0R ( 0R as now , TR4). That was to clearly show how it changes the sound. What you might notice is the sound becomes softer with perhaps more detail when 47R. The latter is hard to understand as from any point of view it should be a bad idea. What could be happening is the TR4 is when 0R a true TIS and when 47R a VAS. Many will prefer 0R as it gives more punch. My friend prefered 0R. Another friend much prefered the 47R. After that other values might be tried. 16R was one I used. My definition of VAS is Zin >3 times greater than the feeding resistor. If the transistor has gain of 100 and 25/icmA we have circa 300 R. If we have 50 R that is 5000R. 30R might be the transition point. It's not in any books and is just something to think about. I often wonder if so called slewing distortion is only the VAS or TIS compromise. No amplifier needs to be as fast as is suggested if sensible input bandwidth is used. 8 V /uS should be OK at 100 watts 6R. Some really dreadful 1960's amps can be transformed by simply adding an emitter resistor to the VAS. The worse example was Goodmans Module 80. The VAS had a diode in the emitter. Simply replacing it with a 56R resistor cured it's problems. Although the DC points were the same the IM distortion wasn't. The designer obviously thought a diode was better as a resistor would be cheaper. It was suggested Module 80 was a germanium design changed to silicon. It used an all PNP output of 2N2955. That is bonkers. The modified Module 80 with new caps where possible sounded rather good.
One thing you could try is a very small resistor in the VAS emitter. When I did this for a friend we used 47R and 0R ( 0R as now , TR4). That was to clearly show how it changes the sound. What you might notice is the sound becomes softer with perhaps more detail when 47R. The latter is hard to understand as from any point of view it should be a bad idea. What could be happening is the TR4 is when 0R a true TIS and when 47R a VAS. Many will prefer 0R as it gives more punch. My friend prefered 0R. Another friend much prefered the 47R. After that other values might be tried. 16R was one I used. My definition of VAS is Zin >3 times greater than the feeding resistor. If the transistor has gain of 100 and 25/icmA we have circa 300 R. If we have 50 R that is 5000R. 30R might be the transition point. It's not in any books and is just something to think about. I often wonder if so called slewing distortion is only the VAS or TIS compromise. No amplifier needs to be as fast as is suggested if sensible input bandwidth is used. 8 V /uS should be OK at 100 watts 6R. Some really dreadful 1960's amps can be transformed by simply adding an emitter resistor to the VAS. The worse example was Goodmans Module 80. The VAS had a diode in the emitter. Simply replacing it with a 56R resistor cured it's problems. Although the DC points were the same the IM distortion wasn't. The designer obviously thought a diode was better as a resistor would be cheaper. It was suggested Module 80 was a germanium design changed to silicon. It used an all PNP output of 2N2955. That is bonkers. The modified Module 80 with new caps where possible sounded rather good.
I had no choice. A gentleman was having his Garrard 401 restored and wanted the Gooodmans brought up to a higher standard. Silly money was offered. The Module 80 was a Thorn BRC chassis as far as we could tell bumped up in voltage and silicon fitted. My late brother did the work. If still alive he would have been very good to know on this thread.
He also did up a Leak amplifier in the same way. The owner said it was a Naim killer. This was going as far away from standard capacitors as possible whilst using common types. Also getting the best from the amplifier stages.
He also did up a Leak amplifier in the same way. The owner said it was a Naim killer. This was going as far away from standard capacitors as possible whilst using common types. Also getting the best from the amplifier stages.
Curiosity in its human nature and You are all very right, that NAIM has its own approach to the sound. And i also was against that mod shown above, thinking that it will take the sound to a different level. Thanks for clearing that up.
The idea came from a buddy, who follow's D.Self Blameless Amplifier editions.
He knows what he is doing with Karlson's 15" speaker cabinets and 100W tweeters, blameless and crest audio amplifier systems.....
He knows what he is doing with Karlson's 15" speaker cabinets and 100W tweeters, blameless and crest audio amplifier systems.....
I myself, compliteing an "u101" radiotehnika amplifier and "A-B Switch Box" from rodelliot
. If this two are done, i would be able to compare in real time
, two completely different schematics.Made few days back a comparison: My Naim Ebay H-140 Clone vs Original Sony RX55
Speakers 8" Finland 40W retro, signal source, all were the same except actual amplifiers.
I noted bad and good characteristic of the sound starting from:
Piano's and ending with todays electro/computer music.
I do not know from what class(A, B, or D) is the RX55 amplifier coming from except that it uses CHIP mounted on a huge radiator.
There is also transformer and PSU caps inside.
There is also transformer and PSU caps inside.
- First RX55 fails to deliver pleasant HIGH(hits, hats) notes. Naim is like an instrument in that spectrum compared to Sony
- Second is BASS, i tought MPSA06 and MJE243 slowed the amp down in bass register(it did BUT it is still more controlled and Tighter then SONY RX55)
- Third, MID-HIGH, here naim is more detailed ...but at the same time more Edged then Sony RX55...... Both were catastrophic in some mp3-s
- Fourth, MID and MID-LOW... both good actually... mid piano notes were pleasant with both amps.
Imaging = SONY RX55 can't do that... cuz its muddy... and muddy sound can't image nothing.... the bass register was also more "boomy" tooo.
Funny thing is that before this amplifier DIY business, i was using SONY RX55 as my main amp... tought it was pretty good lol...
About VAS resistor... i have 220R 1W resistor before that VAS and LTP, like in NCC200 schematic(both -/+ DC lines have 220R to the FRONT-END)... should i remove it ?
I remember changing it to 100R, noticed DC mV drift on the output from 4mV to 10+mV
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We often change our views when we hear something that really excites. The aim is different with strictly high fidelity amplification, which principally aims to reduce noise and distortion to insignificant levels. The result may be electronically perfect and essential for professional applications but for many people listening at home, perhaps in a small space at low levels, the result is not always satisfying or exciting.
The solution is not mysterious. While people talk of pace, rhythm, timing, air and other vague subjective terms, audiophile sound quality usually comes down to ensuring there is some very small but carefully tailored range of low order harmonic distortion produced in the amplifier, not so much in the signal processing chain.
Engineering designers don't seem to have much time for these amplifiers they call "effects boxes" but this is not about technical assumptions and aims, it's about satisfying the user, whether it is a commercial or DIY product. I believed the notion that perfect specs meant perfect sound until after many auditions in retail listening rooms, I could not figure why the highest spec. amps sounded least entertaining. Then, when I listened many years ago to a complete, new Linn/Naim system, the penny dropped.
Naim is like Harley Davidson. Everything is wrong yet that is the product. Something already in doubt in 1930 lives on. Harley put two cylinders where one should go. The engine has less parts than most. The angle is about 60% of what would be better. Here the analogy with Naim is strong. The Naim mimics a single input transistor whilst maintaining op amp style simplicity of DC conditions. One should rememeber all speakers grew up with either the single input transistors or valves. The dry as a bone modern amps are not typical of then. Jean Hiraga was to show later on that how Naim is configured might sound of lower distortion than the "ideal " current mirror input stage. I read some years ago that the Naim sound is a predominace of thrid harmonic distortion. This is as far from the truth as is possible. The reviwer stated the pace of the amplifier came from this. Sadly I trusted this statement. Removing the second harmonic is a bit little bit like playing a Cello concerto on a Violin. It can be done and mostly will sound right , but it will not be right. The daft thing is much is said without any reality check. How music works, typical hearing and total system distortion are ignored.
The signal transmission time through the lower and slower Complementary pair in the half differs from upper the Darlington pairing.
The forward feed networks to the driver transistors e.g. NAP250 adjust the phase of each push-pull half to avoid the mismatch that would otherwise arise in the combined output and feedback signals.
The use seems to be reserved for the high end Naim amplifiers.
I have just been given a Naim AV1. I never knew it existed. I had said to a friend about Hafler 4 speaker stereo . She thought I should have this. Digital processing of LP's in the early days made surface noise more obvious ( Dolby ). Worse than low grade turntablles. I suspect it still would today and might say why digital isn't the complete miracle we hope for. I have heard very good CD against analogue mastertapes and can say the sound is strangely different. Almost like a tribute band. A LP less so and a 78 microgroove cut almost identical ( played in real time as a test piece for the lathe). The CD didn't sound tonally right which is hard to understand. The man who did the transfer to CD was rather upset as he thought it was his best work. He didn't say, but it showed on his face. He mastered Paris Texas LP if wondering, many know that one.
I went to a London store in the 1970's. They showed the cheapest speakers they had on demo ( AR7 ? ). It was wonderful. The guy then said I shouldn't run away with the idea I would get that sound. He was playing what he called a mastertape. This was a very big room. It was filled with sound that had plenty of bass. Certainly I have heard similar since. This was the first time, about 1971 I guess. This was years before Linn and Naim said FRIGRO, feed rubish in, get rubbish out. The reference to computers was made.
The Hafler did the opposite. It semed to throw the noise outside the listening circle.
Here is the RCA circuit most speak about. It is as similar to Naim as me and Michael Caine. Compared with Frank Sinatra me and Michael could be twins as we both are English from similar origins and the same height. I met him once. More impressive in real life.
RCA Circuit Used By Naim Photo by John_Luckins | Photobucket
I went to a London store in the 1970's. They showed the cheapest speakers they had on demo ( AR7 ? ). It was wonderful. The guy then said I shouldn't run away with the idea I would get that sound. He was playing what he called a mastertape. This was a very big room. It was filled with sound that had plenty of bass. Certainly I have heard similar since. This was the first time, about 1971 I guess. This was years before Linn and Naim said FRIGRO, feed rubish in, get rubbish out. The reference to computers was made.
The Hafler did the opposite. It semed to throw the noise outside the listening circle.
Here is the RCA circuit most speak about. It is as similar to Naim as me and Michael Caine. Compared with Frank Sinatra me and Michael could be twins as we both are English from similar origins and the same height. I met him once. More impressive in real life.
RCA Circuit Used By Naim Photo by John_Luckins | Photobucket
Yes, same image as that posted on Avondale Audio's site prior to the 2013 makeover. I get the impression Mr Wolstonholme was using it to illustrate the origin of those driver base networks referred to by mjona, (above). There's not much else in common as you suggest and I don't think he would suggest other similarities that plainly don't exist.
I know Les and like him. He was at a show when prizes were given out and said he never got prizes. The reason being he based business on improving Naim designs. Much of his work is logical and correct. It has caused some to say he has lived from the sucess of Naim and is harmful to Naim. I wouldn't like to offer an oppinion on that. Les perhaps like people here has mistaken the circuit for the product. As Julian Vereker said " Some people say my amplifers are 80 % power supply . Mostly that is right ". I am sure that isn't the exact words, close enough. What people do not realise is the whole range were alike. The NAP 250 having a power regulator much like a power amp. If you like a big LM317 in descrete parts. Les bought the story of the RCA and thought the Naim's were also a copy ( right idea, wrong origine). I asked Bob Stewart why he let Naim produce a Bob Stewart idea first. J V went to a lecture given by Bob. " Causes of distortion in amplifers due to loss of imformation " or about that. At the end Mr J V asked how he would make an amplifer like that. Bob said take a Sinclair Z50 ( 1969 ) and get it to be tough enough. Then build it a power supply of great size. Bob said " I didn't exspect him to do just that and sell it ". Bob wasn't the right one to do it. His 105 was already moving on from there. The Lecson was more like it.
An interesting anecdote. There is some discussion on the early days of Naim from the man himself at Julian Vereker's Last Interview - The Tom Tom Club.
I think I saw this many years ago and remembered the observation about the phase correction networks and his attributing the source to an American company mentioning the name Spectra-sonics History ? Spectra Sonics who manufactured a range of studio equipment - a line of business Julian Vereker was developing in England.
The interview on the Tomtom site is interesting, but you might like to not see the comment about the Quad 303.
I have a record by The Tom Tom Club, I wonder if that's the reason why it's named that way?
J V singles out Quad. Mostly they were selling units instead of him as to why he said it ( his engineer was thwarted by Mr Walker it has been said ). The Quad 303 is a remarkable amp when given a chance. I am sure Julian didn't know much technically as the NAP250 is in many ways an exact 303 clone, many who knew J V said it was who worked for him that made Julian's wishes come true ( Mr West ). In many ways the 303 is a better piece of engineering, it turns it's problems into advantages. The 303 has a single transistor regulator which is not like conventional series regulators. The 303 was intended as a professional unit which the public could buy. 70% of Quad sales were single power amps for mixing desks etc. 303 has a very cautious protection circuit that really work. It is the simplest I ever saw as an add on device ( MOS FET's just cope. They seldom need anything, they act like the Quad ). The 303's big problem ( if that is true ) is when the protection is working you might not know. It will make the amplifer sound less dynamic. Julian knew the era when 82 dB/W for spearkers was common and bad phase changes. With a well designed speaker the 303 comes close to perfection and is very dynamic compared with it's modest build. Magnepan SMGa is great with them. The Quad will save the SMGa from trouble as a bonus.
The Sinclair story from Bob Stewart I seem to remember was told to me about 1980. Bob also told John Dawson of Arcam the same story and helped the young A&R company. I owned A&R A60 SNo 301 bought with my very first cheque from John. It is a mystery to me why Bob did not make what he recomended to the man who asked questions, Mr J V. The Meridian 105 which was a genius device is too small to be what it could have been. Bob Stewart's problem is he gave the lecture but did not listen to himself. Bob told me he was too involved with other things to chalenge Naim at the time. You should have seen the smile on his face as he told the story. He was very warm hearted about it. Perhaps what Bob said would never have seen the light of day if J V hadn't had a near religious understanding of what Bob was saying. For J V I suspect it was life changing. It is rare in this world to be listened to. Maybe Bob was thankful as the path had been made for other ideas. The Meridain CD player of early vintage is still one of the best. Bob and Michael Gerzon really understood how to get digital to work. Michael was the most inspirational person I ever met.
J V told me a bit of nonsense years ago. He implied that using a NAP250 with other make preamps would be dangerous if wrong. His reason being that bandwidth limiting was a complete pakage. He went on to say less stages were needed if so and this looses less musical imformation. His best statement was a NAP 250 could project a speaker cone 30 feet in theory. I know how these things happen. I tell my boss similar things. Inside of 1 minute he stops listening. Then what I said comes back to me without the qualifying statement I made. The dangerous statement was dangerous to J V as he was a control freak. I admired and liked him. I wasn't deaf to his self promotion. With Julian you did learn better ways of thinking. Alas with me it told me to use my ears and not join a religion. The starangest thing he ever said to me at a hi fi show was. " I don't know theese people, I know you ". He then went on to share interesting things which I don't think were self promotion. I think Julian knew I was not convinced by the things he said. He also knew I did not question that he was asking the right questions.
One myth that was promoted was that Naim did not use protection circuits. The myth stated that the amplifers were tough enough not to need them. Naim unlike any company of the period did not publish repair imformation. Also repairs were rare. It took years to find out that the Naim amplifier was very obvious and to be honest primitive. The other fact that is missed is that the power supplies were very different. The primary of the transformers were at the limit of what our 13 amp mains fuses could stand on start up. Most fuses will cope with 2 x rated current when so. The NAP 160 which is the most important Naim design is a very unremarkable amp as would be the original Ford V8. I hope the correct irony of that is not lost on people.
A small company Lab47 uses a chip amp and fantastic PSU. Many would prefer it to a NAP250. Also read Paul Kemble. One advantage I have is I knew Julian. I doubt if anyone one did know J V having said that.
J V singles out Quad. Mostly they were selling units instead of him as to why he said it ( his engineer was thwarted by Mr Walker it has been said ). The Quad 303 is a remarkable amp when given a chance. I am sure Julian didn't know much technically as the NAP250 is in many ways an exact 303 clone, many who knew J V said it was who worked for him that made Julian's wishes come true ( Mr West ). In many ways the 303 is a better piece of engineering, it turns it's problems into advantages. The 303 has a single transistor regulator which is not like conventional series regulators. The 303 was intended as a professional unit which the public could buy. 70% of Quad sales were single power amps for mixing desks etc. 303 has a very cautious protection circuit that really work. It is the simplest I ever saw as an add on device ( MOS FET's just cope. They seldom need anything, they act like the Quad ). The 303's big problem ( if that is true ) is when the protection is working you might not know. It will make the amplifer sound less dynamic. Julian knew the era when 82 dB/W for spearkers was common and bad phase changes. With a well designed speaker the 303 comes close to perfection and is very dynamic compared with it's modest build. Magnepan SMGa is great with them. The Quad will save the SMGa from trouble as a bonus.
The Sinclair story from Bob Stewart I seem to remember was told to me about 1980. Bob also told John Dawson of Arcam the same story and helped the young A&R company. I owned A&R A60 SNo 301 bought with my very first cheque from John. It is a mystery to me why Bob did not make what he recomended to the man who asked questions, Mr J V. The Meridian 105 which was a genius device is too small to be what it could have been. Bob Stewart's problem is he gave the lecture but did not listen to himself. Bob told me he was too involved with other things to chalenge Naim at the time. You should have seen the smile on his face as he told the story. He was very warm hearted about it. Perhaps what Bob said would never have seen the light of day if J V hadn't had a near religious understanding of what Bob was saying. For J V I suspect it was life changing. It is rare in this world to be listened to. Maybe Bob was thankful as the path had been made for other ideas. The Meridain CD player of early vintage is still one of the best. Bob and Michael Gerzon really understood how to get digital to work. Michael was the most inspirational person I ever met.
J V told me a bit of nonsense years ago. He implied that using a NAP250 with other make preamps would be dangerous if wrong. His reason being that bandwidth limiting was a complete pakage. He went on to say less stages were needed if so and this looses less musical imformation. His best statement was a NAP 250 could project a speaker cone 30 feet in theory. I know how these things happen. I tell my boss similar things. Inside of 1 minute he stops listening. Then what I said comes back to me without the qualifying statement I made. The dangerous statement was dangerous to J V as he was a control freak. I admired and liked him. I wasn't deaf to his self promotion. With Julian you did learn better ways of thinking. Alas with me it told me to use my ears and not join a religion. The starangest thing he ever said to me at a hi fi show was. " I don't know theese people, I know you ". He then went on to share interesting things which I don't think were self promotion. I think Julian knew I was not convinced by the things he said. He also knew I did not question that he was asking the right questions.
One myth that was promoted was that Naim did not use protection circuits. The myth stated that the amplifers were tough enough not to need them. Naim unlike any company of the period did not publish repair imformation. Also repairs were rare. It took years to find out that the Naim amplifier was very obvious and to be honest primitive. The other fact that is missed is that the power supplies were very different. The primary of the transformers were at the limit of what our 13 amp mains fuses could stand on start up. Most fuses will cope with 2 x rated current when so. The NAP 160 which is the most important Naim design is a very unremarkable amp as would be the original Ford V8. I hope the correct irony of that is not lost on people.
A small company Lab47 uses a chip amp and fantastic PSU. Many would prefer it to a NAP250. Also read Paul Kemble. One advantage I have is I knew Julian. I doubt if anyone one did know J V having said that.