NVA AP20 INTEGRATED AMPLIFIER

NEW PRODUCTION NVA AP20

 

The AP20 is a real quality cost effective integrated amplifier. This is a four input amplifier of very high sound quality

AP20 Specifications

Inputs - Four line level

Outputs - 4mm speaker sockets

Power supply - 1 x 100 VA

Power Output - 25 W per channel

(whd)

- -

Hi-Fi Choice Review

NVA AP20

The NVA remains one of the last bastions of minimilist UK hi-fi, right down to to the throughly utilarian and utterly impregnable casework! You'll either love it for its purist ideals or loathe it as an anachronism.

Either way, the AP20 is as accommodating an anachronism as you'll ever find, one that's available with either MM or MC disc stages (but not both) or, alternatively, with neither. Got that? Good because round the back you'll discover standard phono sockets for CD, tuner, disc and tape.

Recessed 4mm sockets are provided for speaker cables, though I'd warn against using high capacitance brands as these might tip the AP20 into instability. High resistance cables, like NVA's LS1, will act as the `Zobel network' that's missing from its own output stage. Just use our cable booklet as a guide.

Lab report

TEST RESULTS

20Hz 1kHz 20kHz

Maximum Continuous Power Output

8ohms 32.5W 35.0W 6.8W

4ohms 39.1W 44.9W 10.8W

Dynamic Headroom (IHF) +2.09dB (56.6W)

Peak Current (5msec, 1% THD) +12.8A

Output Impedance 0.0065 Ohm

Damping Factor 1238.5

CD/Aux MM

Stereo Separation

(1kHz) 81.4dB 78.0dB

(20kHz) 64.8dB 57.9dB

Channel Balance

(1kHz, -20dBV) 0.49dB 0.52dB

(-60dBV) >50dB >50dB

Total Harmonic Dist.

(0dBW) -60.7dB -64.2dB

(2/3 power) -71.4dB -70.9dB

CCIR Intermod. Dist.

(0dBW) -62.5dB -63.3dB

(2/3 power) -26.6dB -26.1dB

A-wtd Noise

(0dBW) -87.2dB -84.4dB

(2/3 power) -98.8dB -87.0dB

Residual noise

(unwtd) -78.6dBV -78.6dBV

NVA has an uncanny knack of designing solid-state amps with tube-like overtones. Weed thinks the whole thing is a real hoot! Ahem. Loose power supply regulation yields a small 1.1dB rise from 35W to 45W into 4 ohm but, the flipside, its +2.1dB headroom and +12.8A current rating are very generous. The 0.0065 ohm output impedance is equally impressive.

Sound quality

Initially alarmed by the noisy swish-swish of the NVA's cermet volume control, our listeners' fears were quickly allayed by the very organised and detailed sound that ensued. Here was an amp that retrieved the airiness and height of Prokofiev's Symphony despite its restrained sense of dynamics and decidely gentle tonal balance.

Nevertheless instruments like the woodwinds, rich in character, were faithfully represented, enmeshed in an equally deep and uncluttered soundstage. Otherwise this hint of softness, this velvety texture only mollified what were described as the `digital excesses' of our pop selection. So cymbals and strings lost the hard and edgy qualities that had been heard earlier in the day, traded for an altogether sweeter hue.

Vinyl was described as euphonic, an easy going presentation but one that lacked the openness and finer detail revealed via CD. Bass, in particular, lacks the resolution, the weight and impact that is available on-tap with the CD input.

Conclusion

As a CD-only amplifier, the AP20 has the ability to reproduce a stunning variety of tonal colours and musical styles, lacking only what our listeners insisted on describing as `grunt'. Stick with sensible low/medium resistance, low-capacitance cable and a pair of sensitive speakers and you too will discover the unforced and delightfully natural performance of NVA's AP20.

WE ARE SO CONFIDENT IN THE QUALITY OF OUR PRODUCTS AND DESIGNS WE OFFER 14 DAY NO QUIBBLE RETURNS POLICY (less p&p)

Available in 120v or 240v please stipulate on purchase

- For full information on NVA go to http://www.nene-valley-audio.com/ -

NVA's Overall Philosophy

Generally, we have never been keen on producing conventional literature, because it's usually just glossy expensive paper full of pretty meaningless specifications which have little bearing on how good the sound of audio equipment is when playing music. If you buy hi-fi equipment on the basis of what a manufacturer says about himself (including us!) you really do deserve what you get.

As an alternative, one of our dealers suggested that we try to explain good design and how to recognize it. People probably won't believe this, but really the basics are very straightforward. A famous British amplifier designer is supposed to have said, "Good amplifier design is not the things that you do right, but the things you don't do wrong". I really wish I had said it first, because it's amplifier design in a nutshell. You can come up with all the new circuit configurations under the sun such as feed forward, low feedback, class A to Z, but ignore the common sense ground rules, and you will have a sonic bag-of-nails capable of being blown away by a couple of EL34's in a 1950 Williamson tube circuit. I am afraid 80% of the amplifiers built today fall into this category. The thing that never stops amazing me is that so many audiophiles keep falling for it. There is nothing like a good story to have people hocking the next three years' spare income on the latest all-singing, all-dancing creation. Not only that, a good story sells magazines as well, which just exacerbates the problem.

Here are my ground rules:

1. There is only one thing better than the best component money can buy, and that is no component at all.

2. Never use two components when you can do the job with one.

3. Screw up your earth (ground) paths at your peril.

4. Always use the largest transformer (toroid if possible) you can cost in.

5. If your ears and your test equipment tell you two different things, trust your ears.

6. If you have a fault in your source material or elsewhere in the equipment chain, you cannot correct it by creating an inverse fault in the amplifier with tone, balance, and filter controls. Two wrongs do not make a right.

After that it is all down to experience, and fine-tuning the design to your own taste. It is easier to get a half-way decent sounding amp using Vacuum State Logic (warm glass bottles) than Solid State Logic (hopefully cool lumps of plastic) because there is less to do wrong (Neanderthal Logic). That is why so many people have jumped on the valve bandwagon. All things being equal, bits of doped silicon encapsulated in metal or plastic (transistors) potentially are capable of doing more things with music, i.e. wider (frequency), larger (amplitude), cleaner (distortion and noise) for less cost. Remember though, the more you try to do, the exponentially easier it is to do it wrong.

If you can get most of it right, then think very carefully before you try to get the very last bit, because you may be too clever and ruin everything you've gained thus far.

This explanation is all very simplistic of course, and common sense and experience must apply as well. For example, a Class A circuit is a lot simpler that the equivalent Class B or AB. Ergo, applying my logic it should be better. Wrong, unless you spend a fortune on the power supply, which then makes the amplifier grotesquely expensive and heavy. The problems of current demand by the amplifier outweigh the simplicity. If I could buy 1000VA transformers not larger than 4" square, and weighing less than two pounds for £10, and if I could get good and consistent output transistors (i.e. not FETs) that could sink 20 amps, and either, not get hotter than 70 degrees C doing so, or stand 150 degrees C without going into self-destruct mode, I would produce Class A amplifiers. I will not produce them just because they have become some reviewers latest buzz word.

Every amplifier has its own sonic character, which is very much down to the musical parameters that are most important to the designer. The process is very much "lose on the swings, gain on the roundabouts". I once knew an amplifier designer, in fact I employed him back in Tresham Audio days to produce a professional FET power amplifier, who saw no necessity for listening to the amplifier at all. It was only after he left, and some ears were applied to the design that it started to sing, not as much as the best hi-fi amplifiers, but it went very loud and was virtually indestructible.

My greatest hang-up is information retrieval - musical information, especially dynamic separation. I will always go for information even at the expense of upsetting the "make everything bounce and swing with the tempo" brigade. My other priority, which seems to be out of favour at the moment, is neutrality, or as I prefer to call it, lack of the irritation factor.

Richard Dunn, Founder and Owner, NVA

- -

PLEASE NOTE ALL NVA PRODUCT IS BUILT TO ORDER SO THERE WILL BE A DELIVERY DELAY AS THE PRODUCTION AND TESTING IS SCHEDULED. AVERAGE DELIVERY TIME IS FIVE TO SEVEN DAYS BUT CAN ON OCCASION GO OUT TO TEN TO FOURTEEN DAYS DEPENDING UPON ORDER PRESSURE

 

PRICE LIST

ELECTRONICS

AP10H Headphone Amplifier £240.00

AP10P Personal Integrated Amplifier - £260.00

AP20 Integrated Amplifier - £350.00

AP30 Integrated Amplifier - £450.00

AP50 Integrated Amplifier - £550.00

AP70 Integrated Amplifier - £700.00

AP80 Integrated Amplifier - £1000.00

P50 Passive Pre Amplifier - £160.00

P50sa Passive Pre Amplifier - £260.00

P90 Passive Pre Amplifier - £240.00

P90sa Passive Pre Amplifier - £540.00

P90 Passive Pre Amplifier plus active phono stage - £350.00

P90sa Passive Pre Amplifier plus active phono stage - £650.00

RVC Remote Volume Control - £120.00

A30 Stereo Power Amplifier - £300.00

A40 Mono Power Amplifiers (pair) - £400.00

A60 Stereo Power Amplifier - £600.00

A70 Mono Power Amplifier (pair) - £800.00

A80 Mono Power Amplifier (pair) - £1000.00

P.S.U. Power Supply for Phono2 and Dacon - £190.00

Phono1 Head / Phono Amplifier (in built psu) - £220.00

Phono2 Head / Phono Amplifier - £260.00

Phono PCB’s – for fitting to nva products – £100.00

CABLES

Sound Cord – per 10cm length pair – terminated - £5.00 (SEE SPECIAL OFFERS)

Super Sound Pipe – per 10cm length pair – terminated - £20.00

Sound Pipe – per 10cm length pair – terminated - £10.00

Sound Pipe Digital – per 10cm length - terminated - £5.00

LS1 – per metre length stereo set – terminated - £20.00

LS2 - per metre length stereo set - terminated - £10.00 (SEE SPECIAL OFFERS)

LS3 – per metre length stereo set – terminated - £30.00

LS5 - per metre length stereo set - terminated - £50.00

Sound Pipe LS - per metre length stereo set - terminated - £100.00

Bi-Wire – per end (speaker and amp) – terminated - £10.00

We offer a 100% trade in value on our products if you trade up within the nva range of like products within two years of your purchase date (only applicable to direct sales from us or through ebay). After that date we will still trade in your item but on a sliding scale as to age and condition. You must print out and keep your ebay receipt or invoice to verify your purchase date.

THIS SERVICE AND OFFER IS QUITE UNIQUE IN THE WORLD OF AUDIO AND HI-FI

NVA AND SPEAKER CABLE SAFETY

For best sound the amplifier should be left powered up. Electricity consumption is very low. It is for this reason that the power switch is located on the back panel, where it may not be easy to reach. Turn the amplifier off when you do not intend to listen to it for extended periods.

NVA amplifiers are unique, and one thing that makes them so is the minimal compensation for the output stage. It is very possible to send this amplifier into oscillation by connecting too large a capacitive load on the output, the usual culprit being unsuitable speaker cable such as Litz or Goertz type constructions. The amplifier normally runs cool, but if it is driven unstable the output transistors will become hot and the sound will distort and the amplifier could fail putting your loudspeaker coils in danger. You can check for this by placing your hand on the amplifier and feeling for hot spots. If you find the amplifier overheating switch off immediately and consider changing your cable.

Only NVA LS1, LS2, LS3, LS5 or SPLS is recommended for use with this amplifier, other cables invalidate our guarantee. If you insist on using other cable please ensure it is no more than 200pf per metre and it should not be used in lengths over 10 metres. If you wish to Bi-Wire this can only be done with NVA cable and they can be made that way on order for small added cost.

For design performance only NVA Soundpipe Super Soundpipe or Soundcord  Interconnects should be used, but this is for sonic as opposed to safety reasons.