NVA Phono 2

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Somethingfunny
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Re: NVA2

Unread post by Somethingfunny »

"You have investigated with what, do you realise how inacurate your measurements are, what was the reference. RIAA is a filter they are all inacurate and inacuracies will change as from used normally i.e. listening to music or connected to a test rig"

I don't understand this? Are the measurements that are inaccurate? Or is Firbottle inaccurate with his measurements, Yes? and how, if so?

"RIAA tolerances"

This give space for changes, as in making it sound a particular way?

It is not illegal to do this. It is ok to make it sound the Doctors way!

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Dr Bunsen Honeydew
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Re: NVA2

Unread post by Dr Bunsen Honeydew »

Zebbo it is just an arse talking out of his arse, it is part of the dissing games that has been going on for years, it has no reality in music. All he is trying to do is make people *not* trust their ears.

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Dr Bunsen Honeydew
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Re: NVA2

Unread post by Dr Bunsen Honeydew »

I can't keep repeating Somethingfunny, I will have to shorten it. Some or thing or funny all don't work STF sounds almost like STFU. Any suggestions.

Anyway what we have here is a classic example of FUD https://en.wikipedia.org/wiki/Fear,_unc ... _and_doubt it needs to be seen for what it is.

Somethingfunny
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Re: NVA2

Unread post by Somethingfunny »

Dr Bunsen Honeydew wrote: Mon Jul 16, 2018 11:35 pm I can't keep repeating Somethingfunny, I will have to shorten it. Some or thing or funny all don't work STF sounds almost like STFU. Any suggestions.

Anyway what we have here is a classic example of FUD https://en.wikipedia.org/wiki/Fear,_unc ... _and_doubt it needs to be seen for what it is.
STFU LOL

SF? or Alb. Either is ok

So this is FUD?.

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Lindsayt
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Re: NVA2

Unread post by Lindsayt »

Firebottle wrote: Mon Jul 16, 2018 8:18 pm
...I personally would have fitted a 47K resistor in place of the 68K feedback resistor to give a flat RIAA response, and probably ditched the 47uF tanatlum capacitor that gives the rumble filter function...
By how much and at what frequencies does the NVA Phono 2 deviate from a flat RIAA frequency response?

And how does this compare to how much anyone's given speakers in their listening rooms at their listening positions deviate from a flat frequency response?

I know 2 wrongs don't make a right. But when one "wrong" is completely swamped by another wrong elsewhere in the system the first wrong becomes unimportant to the point where it bears no impact on any sensible buying decision.

This leaves other wrongs on which I will base my buying decisions. Price. Clarity. Transparency.

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Dr Bunsen Honeydew
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Re: NVA2

Unread post by Dr Bunsen Honeydew »

Still clearing the FUD up and reactions to it, any more will be removed as well. what is here will stand until the units are compared AGAIN!!

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Dr Bunsen Honeydew
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Re: NVA2

Unread post by Dr Bunsen Honeydew »

As can be seen there are variations in application both at manufacturers of cutters, also in the tape machines used (a tape head alters and filters the sound). The frequency curve is altered at every stage in the recording and playback process, from acoustic to mic to desk EQ - through the whole process to the speaker and your ears. NOTHING IS ACCURATE IN TECHNICAL TERMS, to say small variations in RIAA are all important is ludicrous, it probably has the smallest variation and need for tolerances in the process.

What we have here is one manufacturer trying to put down another manufacturer with FUD. In practice RIAA has always had a wide tolerance to compensate for the different ways recording companies did things, and it is little known but the curve used in 45s is different to that used in most 33s rpm. to say one way is totally accurate is bullshit. RIAA equalization is a form of pre-emphasis on recording and de-emphasis on playback (like Dolby). So accuracy of playback (de-emphasis) depends on what messing around has gone on in the production process (pre-emphasis).

https://en.wikipedia.org/wiki/RIAA_equalization

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Dr Bunsen Honeydew
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Re: NVA2

Unread post by Dr Bunsen Honeydew »

More relevant information which can be discussed as long as not used to continue individual product promotion or dissing.

The effects of tube ageing on the RIAA filters and other amplifier stages.

When tubes age, the cathode emission decreases. This is what tube testers try to test: either they test the emission (cheaper testers) by measuring current through the tube when it's connected and behaving as a diode, or the expensive testers test the transconductance of a tube. There is also a company also claiming to test the tubes for gain.

How does the decreased cathode emission affect the sound then? In general there are two tube parameters involved: The S / GM / Transconductance of the tube decreases which will result in less gain for the same input voltage. Do we care? Well we do for the sake of total gain of the amp, but in most cases we will just turn up the volume a little more. For some phase splitter circuits etc. It can be an issue if both parts of such a phase splitter are not the same tube and age differently (for example we do not use double triodes).

But for phono amps another parameter is more important, if tube ageing affects the plate resistance (r_a) of the tube. In this case that effective plate resistance will increase significantly, the output impedance of the tube will increase as well. Remember that for CCS the output impedance is the effective impedance of Rp and r_a in parallel. Therefore the value of R1 in series with Z_out of the tube will increase and our filter is not calibrated anymore.

My point - well nothing is perfect and valves have problems here that don't exist for solid state circuits. Also this is not a "it works / it doesn't work" aspect, this is a continual wear process like that of stylus wear altering response.

There is an agenda at work here that is prominent at AoS largely because of Marco, and as with all his pronouncements it is nonsense. It has continued with things like the Stoke bake-off and also now being used, as with this thread, to try and make a created valve v solid state delusion have some reality - it doesn't. A good phono stage is a good phono stage - full stop. There is only one proof in this, not the opinion of those with agendas but the opinions of users with their music their ears and their systems and their rooms, everything else is BULLSHIT! Best is loans, so any valve phono stage owner member here is very welcome to have a loan of a NVA unit to hear for themselves, a second less good alternative is attend a bake-off and bring the unit for comparison.

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Andy-831
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Re: NVA2

Unread post by Andy-831 »

From a personal perspective, I have used Glen Crofts valve phono and Guy Seargents valve P10 in the past but currently in residence is a Phono 2 and pair of PSU's make of that what you will. :grin:
Analogue
401 / PU7 / AT33ev
Longdog Audio Quartz Garrard PSU.
Longdog Audio Phono stage (MCj1)
Digital
NVA BMU.
Innuos Zen / Caiman Seg and Dorado
Cambridge CXC
Amps
Tron Seven Linestage.
Bel Canto Set 40, or LDA 300B Set Monoblocks
Speakers
Tannoy GRF Memory.
Tannoy ST100 Supertweeters

Lurcher300b
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Re: NVA2

Unread post by Lurcher300b »

There is a small inaccuracy in what Richard said, the gain of the valve remains constant, its fixed by the geometry in the valve, but the transconductance will decrease and the anode resistance will increase (as written). because the gm decreases, the amplification of the stage may be reduced as the overall gain of the stage is set by the load resistor and the valve transconductance interaction, not the gain of the valve. All of what Richard said was true, but for that small correction.

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