Where has the NDX into Hugo thread gone?

Gandalf_fi,  I agree that systems are important to relate to when reviewing a source. In my 282/250.2/HiCapDR with ATC SCM19 with some room treatments system I found the Hugo has built on the separate strengths of the NDS/555PS and NDAC/555PS. I wrote about this in the context of specific recordings  on the thread we are still waiting to return.

In short I find the Hugo seems to match well with the Naim character and shines with uncoloured revealing speakers where the musical textures, timbres, subtle details, phrasing and dynamics can be appreciated with out being thrown at or etched out for you.

But as we have read elsewhere on this forum  perhaps more filtered speakers might not be a great match.

Simon

He is quite right.  A pre-amp is an analog device and so to some extent will degrade the sound.  In the case of very high quality pre-amps this will be very little but it will be there.

Matching a pre and power amp is not difficult.

Generally best not to use a valve pre-amp with a semi power-amp.  The reason being that generally valve pre-amps cannot output a lot of current (have a high output impedance) and semi power-amps tend to have (cf the valve variety) a lowish input impedance and will possibly load the valve pre-amp more than it likes.  On the other hand valve power amps tend to have a very high input impedance and will be fine fronted by valve or semi pre-amps.

But if the Hugo has a decent pre-amp built in which can supply a decent amount of current then it will drive any power amp.  Remember any DAC will require a built-in pre-amp anyway.

Remember also that a pre/power amp interface is not about maxing the power transfer like in the power-amp/speaker interface, where we require the output impedance of the amp to be close to the input impedance of the speakers.  No the requirement here is not to load the pre-amp too much causing the signal level to drop.

You will only use a separate pre-amp if you need (a) a bit of gain, (b) require a phono amp, or (c) need controls like volume, balance or tone controls (erk!) Many people use passive pre-amps and these are basically no pre-amp with a potentiometer as a volume control but they might have a phono amp built in.

So yes his statement is correct but you may not notice the degradation if you have a top-notch pre-amp.

You're talking about pre-amps degrading sound in a narrow scientific definition only.

It is quite clear how an active Naim pre-amp sounds better than a passive pre-amp. Try it yourself.

You appear not to realise that people use pre-amps because they choose to have the active effect. It is not simply for the extra controls or a bit of gain as you wrongly state.

You're talking about pre-amps degrading sound in a narrow scientific definition only.

No I am not!  Look at the specs of your (or anyone else's) pre-amp and a part of this spec will be a distortion figure and a noise figure and will be quoted in such a way as to make the kit look as good as possible.  You have to accept that all pre-amps will degrade the sound because of this distortion.

It is quite clear how an active Naim pre-amp sounds better than a passive pre-amp. Try it yourself.

Again no it isn't and I have tried this little experiment, so I know that under certain conditions a passive pre-amp will beat any active one.  But, and it is a big but, passive pre-amps need careful matching with the power-amp.

You appear not to realise that people use pre-amps because they choose to have the active effect.

I have absolutely no idea what an 'active effect' is, perhaps you could explain it please Mark.  btw doesn't the active pre-amp in the Hugo have this elusive 'active effect'.  If you have a DAC that produces a healthy signal, ie more than enough to drive long cables with a tranny power-amp at the end of the cable, then unless you want to connect in a whole load of other kit and it has a volume control then don't connect through a pre-amp.  If the pre-amp in the Hugo is poor then plugging it into the best pre-amp in the World won't make it any better.  I can assure you.

It is not simply for the extra controls or a bit of gain as you wrongly state.

So the controls are not important huh?  Well if you use a tape deck or a tuner etc then the switching will be crucial.  It might also be the only volume control you have, as it is on my analog system.  Finally if your phono amp only churns out 1V then you might struggle to get a suffcient volume for your listening pleasure.  These are the reasons why you buy a pre-amp!  Wrongly state????  read up about pre-amps Mark before you accuse me of being wrong.

Sorry Mark but I an struggling to see why you can't understand this, it is a sad fact of analog reproduction.  EVERY STAGE DEGRADES THE SOUND.  You can't beat physics Mark.

Bill, not going to engage with long-winded 'look-at-me' posts. Pedantic points on a narrow definition.

Ask yourself this. If a passive pre-amp, available for £100 or so, improves on Naim pre-amp, how have they sold so many 52,'s, 82's, 72's, 282's, 252's, 552's etc? In addition, if all they do is provide switching and volume controls then why do they sound different?

It might help you to think about what the pre-amp adds, not what it takes away.

This has nothing to do with 'look at me posts'.

You are struggling with the misapprehension that a pre-amp 'adds positively to the sound'.  Sorry Mark this is nonsense.

Mark I know what a pre-amp adds, for the sake of some gain and the flexibility of controls and switching it adds a bit of distortion and noise.  A very good pre-amp will add very little and I accept that the NAIM models are very good and will add little.

The goal of pre-amp designers over the decades has been to design a pre-amp that adds NOTHING.

A passive pre-amp adds nothing but as I said before needs careful matching.  If this wasn't true then why have so many passives been sold over the years?

Perhaps you could tell me what is this magic that a pre-amp adds?  What is this exotic concoction that the designers put into kit that takes an analog signal and make it look much more like the original analog signal?  Because basically that is what you are saying.  A passive adds nothing so if the passive is matched well to the power-amp and your pre-amp sounds better than the passive then your active pre-amp must be cleaning up the signal.  Sorry Mark that is nonsense.

Mark, Bill,

Are you both willing to listen to an argument that shows that you are both right, just in different contexts?

(This argument is based on my experience of designing pre-power combination using active and passive pre-amps.)

Back to the topic please... We are not in a pre amp thread!!!

No.

I have my own experience of building and designing amps.  If you think that pre-amps add positively to the sound then fine but I don't wanna hear it.

Take it up with the guy who designed the Hugo, obviously not as talented as you Huge but he has done a bit and he says a pre-amp will degrade the sound, which is true.  As I said at the beginning all analog components will degrade the sound - even a cable.

I actually said that you were right (as equally was Mark in a different context to you), but since you don't want me to help explain how that can be, I won't.

However both your sarcastic disparaging comments and the implication that you already know what I'm thinking are unwelcome.

You are not correct in your beliefs on what I think.  I did not state what you seem to believe that I think.  I was respectfully offering to support your argument and your response was needlessly discourteous.

Huge why on Earth would I want your support?  I can get on very well by myself.

Me and Marky were very happy having our own little argument and we were both enjoying it.  Nobody asked you to butt in but I guess we all knew you would be an expert.

Thread is getting hot and not for the weather. We should all know where it will soon be gone.. to find an answer to our next thread: Where has Where has the NDX into the Hugo thread gone thread gone? 

Chag -

I suggest you exchange private mail then and take it elsewhere....

Loosen up a bit.  I will remember this the next time you disagree with someone.

Huge once promised me that he would ignore my posts in the future and he has broken this promise.  He always claims to know everything about everything and yes I now realise that he will almost certainly hit the report abuse button and this will all disappear.

At least me and Marky were having a good humoured rant at one another.

Perhaps you might like to put your views on what the designer of the Hugo said about using a pre-amp?  Because that was all this was about.

Doesn't the Hugo have a pre-amp?

Is it not therefore a comparison of Hugo's pre-amp (analogue stage) versus a NAC, before signal gets to the power amp?

Maybe I am missing something more technical there.

No, you're not missing anything apart from naming conventions: you got it in one.

The Hugo has a section in it's digital logic that functions as a control amp and an analogue output buffer / driver that functions as a pre-amp when it's used to drive a power amp.

Yes you are quite right it has a pre-amp as do all DAC units.  Following the D to A conversion it boosts the very low signal level and will also boost the current level so it can drive long cables.

The point the designer was making and I was also trying to make is that connecting the Hugo into a pre-amp is not required unless you need switching for other equipment, volume, balance, tone controls etc, because you certainly won't need any gain.  Does the Hugo have a volume control built in btw?

If a DAC has a duff pre-amp then connecting it to your system via a brilliant NAIM pre-amp won't make it sound good.  I think people forget that if a designer has created a great DAC stage then he must also design a great pre-amp stage.  Some designers have even gone to the trouble of producing a valve pre-amp stage in their DACs, for example AudioNote.

I remember one of the Quad designers some years ago saying that the ideal amplifier was a piece of wire with gain.  Surprisingly he got a lot of flack over that statement - mainly from HiFi journalists.

Yanc I can't see how your naming conventions are wrong, the pre-amp stage as you say will be in the analog section of the DAC.  Maybe it will be more correctly called its output stage.  The Hugo's designer state in their literature that the pre-amp stage is all class A as of course are all modern pre-amps, never come across one that wasn't.  When someone mentions class A we are talking analog stage NOT digital. How could it possibly be in the digital section because it does follow the D to A conversion after all?

Yes, output stage is a better description I think; saves confusion. Having built a fair number of DACs, it's pretty clear the output stage has a profound effect on the sound quality of the DAC (not done a valve one yet). For my second, all-digital input, system I wanted to eliminate as many boxes as possible and currently use a Naim V1 for the purpose (I wanted remote control switching of inputs and volume. Managed the latter DIY but the former got a bit flakey so I chose the easy option). I originally used a NAC122X preamp & the sound was definitely a bit better using this.

In my simplistic way, I look at it like this - whichever way you cut it, you need to increase the volume from the DAC chip to listenable levels. If you use an active preamp then part of this volume gain is carried out by the preamp, requiring less gain from the power amp than if using a passive pre. I confess I really don't know the detailed technicalities of this but I assume the initial amplification is the most crucial in ensuring good sound quality. 

Take your point Tony but manufacturers don't make DACs that have microscopic output voltages and that can't drive cables.  Obviously not the same people who make Moving Coil cartridges.

Besides from what I remember, the Red Book specification outlined the output requirements at 3V thus making an output stage mandatory.

It is very difficult to understand why playing your V1 through a NAC122X sounded better than playing the V1 straight into you power-amp, because it will still go through this stage.  Unless of course you were able to bypass the pre-amp in the V1 but I doubt that because you will have to drive a cable.  The switching argument I can understand though and that plus a volume control and the 6-12db of gain most pre-amps provide are the main reasons we use pre-amps.

In the days when we used to use separate tuners (I still do on my analog system) you would need a bit of gain.  I think most tuners back then only output 1V (line level standard???) and that wouldn't drive most power amps.  I built a pre-amp with an Erno Borbely JFET phono stage (boards and component kit) and a passive pre-amp using very high quality stepped pots and it does struggle with my Quad FM4 tuner to provide a sufficient volume.  The phono amp provide plenty of juice and sounds brilliant playing LPs.

I won't blunder into areas I don't properly grasp, but the DACs I've been using recently are based on the Twisted Pear design & have all used the Sabre 32-bit ES9018. This has an inbuilt digital volume control but this is a current output DAC & requires an I/V stage which then amplifies the signal by boosting to (in this case) a maximum 2.1V. You can use this volume control via I2C using an ADC to read the position of the potentiometer on the board. If you just use the fixed output you bypass this additional level. Maybe this explains it? (or, not...)

Tonym,

I think you've got it right.  You definitely have to have the gain somewhere.

It's better to have a dedicated gain stage to change low level, medium impedance signals into medium level low impedance.  This provides a better drive to the input of the power amp.  the corollary is putting all the gain into a power amp that can be driven from higher impedances sources, and that compromises its design somewhat, and may also present greater problems with cables (but is still necessary for passive pre-amps).

Why it sounds better with a(nother) pre-amp?  That's a harder one.

There is however, a possibility:  All amplifies are to a degree non-linear devices.  Despite the designers intentions, the output isn't quite a precisely scaled version of the input, there are unavoidable changes in the amplitude / time relationships.

These can include non-linear and frequency / rise-time dependant propagation delays.  These slow parts of the signal differentially, affecting transients and phase relationships.

There are also distortion effects that subtly affect the harmonic relationships, and these can also be frequency / rise-time dependant.

These differences are mathematically interdependent.

The ear/brain combination process both these sources of information to produce what we 'hear'.  If a pre-amp were to add a small amounts of distortion to some parts of the signal, it's possible that this could fool the brain into thinking that the time shifts were less severe.

N.B.  I'm not claiming that this IS how a pre-amp can appear to improve the perceived sound, just illustrating a possible mechanism (there are others based on similar principles).

Just looking at the Twisted Pear site - very interesting - I have not blundered on this company in the past and they look to have some really good products.  Which board(s) did you buy?

Yes bypassing a cheap pot will generally improve things!

Those discussions about the utility of a preamplier with digital sources only are interesting. The reason I think the Hugo could drive a Naim amplifier is because the Hugo have a low output impedance and enough current to drive directly a pair of 90db 8ohm loudspeakers. Second, it's digital volume control do not degrade sound.

It seem many people discussing about the capabilities of the Hugo dot not own it otherwise there would already been a few reports about it's effectiveness when used directly with a power amplifier.

Do modern Naim amplifiers still need bandwidth limited input signals?

Hi Bill,  if you want to find out more, and you've a few days to spare(!) take a look at the thread in the DIY forum over on pfm entitled "Buffalo II -assembly for the Electronically Bewildered" I originally started. (I'm Suffolk Tony over there by the way). Lots of interesting stuff.

Yes that would be interesting.

As I mentioned earlier in the thread, the claim about "no degrading sound" was also made by Weiss when they produced the DAC202 with volume control a few years ago.
But, when I home demoed it (going directly to my NAP) was a considerable degrade. DAC directly to NAC and then NAP was much better.
I never got a satisfactory answer when I asked them about it, so I gave up with the plan.
Most reports on the net, also point to folks getting better results going through a "proper" pre-amp.

I wonder if that last statement has something to do with it.
i.e The Interface between pre and power amps is not a universal standard, and therefore one is better off using a combination from the same manufacturer.