NVA AP30 INTEGRATED AMPLIFIER

NVA AP30

The AP30 forms the fourth in the range of integrated amplifier.

AP50 Specifications

Inputs Six line level

Outputs 4mm speaker sockets.Tape out.

Power supply 1 x 120 VA

Power Output 30 W

Dimensions 430mm x 90mm x 320mm (whd)

AP30 Integrated Amplifier

An internal phono stage is available for this amplifier. For turntable use you must use that or an external phono stage like the NVA Phono 1, Phono 2 or equivalent. All 6 inputs are identical and hardwired to the selector switch using silver alloy cable with PTFE cover. The output of the switch is routed to the potentiometer and tape socket again with the silver alloy cable. The potentiometer is a very high quality. The signal is then routed to the amplifier PCB again with silver alloy cable. The pre-amp stage is entirely passive. The input to the power amp stage has minimum capacitive and inductive coupling and has been designed to operate correctly with the variable impedance output of a passive pre-amp stage. A current mirror operates at the pre-driver stage to ensure that the voltage rails track each other correctly. The driver stage has both current and voltage amplification using devices that could be used as output transistors. The output devices are 12 amp darlingtons and there are two per channel.

The power supply is based around one 120va transformer. A two way smoothing stage is incorporated in the supply. There is no protection circuitry or filtering on the output of this amplifier so care must taken in its usage.

Do not short circuit the output. Do not use bi or tri wire (unless nva LS1 or LS3 or LS5) or high capacitance or litz type loudspeaker cables as these will damage the amplifier as they create a virtual short circuit at very high frequencies which will create instability in the amplifier. As a rule of thumb avoid cables with a capacitance higher than 200pF per meter. Simple solid core or low capacitance stranded cables are cost effective but high quality silver or silver alloy cables such as NVA LS1 or LS3 are best. Avoid loudspeakers with an average of below 4 ohms load impedance or loudspeakers using high frequency notch filters in their crossovers. This amplifier has minimum capacitors, no inductors, and is a low negative feedback class AB circuit design that is unique. The amplifier has an output of 50W per channel. The case design has been created for sonic reasons and is glued and insulated to stop induced circulating currents and static charge problems associated with normal case designs. Due to the power supply nature of the design of this amplifier do not expect it to reach the design sonic performance until used for at least one week from new. It is recommended that the amplifier is left on at all times. Loudspeaker cables can be disconnected but do this at the amplifier end to avoid short circuits.

CYBERFI REVIEW

NVA AP30 INTEGRATED AMPLIFIER

The NVA AP30 integrated amplifier is a 'low budget', pared down development of NVA's Statement series minimalist amplifiers. It uses the fewest possible components with the bare minimum of interfaces, switches, links and other sources of distortion. The AP30 is normally configured as a line source amplifier. However a phono stage can be added, at little extra monetary cost and the loss of one line input. NVA recommends the use of its own ultra low loss speaker cable with the amplifier on the grounds of preferred sound quality. Care should be taken not to use the amplifier with Litz cable. NVA warns that such cable runs the risk of causing high frequency instability. CYBERFi Editor Jonathan Kettle found that the AP30 did prove unusually sensitive to different cable type, its presentation changing dramatically for the better when partnered by NVA's own LS1 cable.

FOCUS ON NVA AP30

The paucity of controls and other external features is a significant clue to the nature of the NVA AP30. It has a volume, on/off switch and four-way rotary source selection control. Inputs through phono sockets mounted on the rear panel correspond with the fascia marks: CD, tape, tuner and disc. Normally the disc input is not a phono amplifier but another line level input. For those who want to play vinyl record using the AP30, a phono stage can be added, raising the price of the amplifier by about 20 per cent.

Clearly the AP30 is less comprehensive design than, say, the Quad 77, reviewed elsewhere in CYBERFi, and herein lies it appeal to audiophiles. Yet it's the very simplicity of this amplifiers design allied to the designer's careful choice of components that suggests it is capable of a high purity of sound. That, and NVA's track record. (If you want purity and earth shattering levels try investigating NVA's Statement series amplifiers culminating in the TDS (The Definitive Statement). The AP30 power output is rated at 30W per channel, though the nature of the design suggests a considerably higher peak output.

Here was an engaging and lifelike sound... For the first week or two I used the NVA AP30 connected to my Snell Type J loudspeakers using Audio Note silver speaker cable. The resulting sound was not entirely satisfactory, there being a slightly raucous edge to the sound. When I mentioned the problem the NVA's designer Richard Dunn he berated himself for not insisting on supplying his own LS1 speaker cable. Replacing the Audio Note with LS1 cable made a colossal difference to the sound, bringing about a balance I could hardly have believed possible. Here was an engaging and lifelike sound with incisive, powerful projection yet without a hint of the previous overbearing brilliance. Complex instrumentation was easily discernible, yet there was no longer the slightest hint of glare. Apart from the amplifiers sensitivity to cable type, my only other doubt about the AP30 concerns its volume control operating logic. The volume control, a cermet (ceramic/metal) passive attenuator of the sort using in NVA's Statement amplifiers, cannot be manufactured to give identical two channel logarithmic operating logic. Having auditioned it on the recommendations of audiophile colleagues within the hi-fi industry, the cermet pot turned out to sound in Richard Dunn's words, 'better than anything else' he'd tried. The quirky aspect of the volume control I had difficulty getting use to is that a high volume is reached rather earlier than usual. I found I rarely need to turn the volume control beyond 11 o'clock, though I suspect heavy metal, rap and grunge headbangers may want to push it round a bit further! My problem was that for the jazz, orchestral, instrumental and choral music I prefer, I sometimes found it difficult to make sufficiently fine level adjustments. Perhaps this difficulty was, to some extent, a psychological one. Often with volume controls, for example, not much happens in the first quarter to third of its travel. With the AP30, the gain is instant. ...the AP30 maintained a consistently astonishing capacity for musical insight... Once installed, warmed up and connected with the correct cables, the AP30 maintained a consistently astonishing capacity for musical insight considering its comparatively low price. Time after time I was struck by the variety of acoustics captured on different CDs. Finely etched nuances were impressively detailed. Little mechanical noises on the Anne Sofie von Otter CD of Grieg Songs; the way she clears her voice midway though track 18; and the vocal purity and brilliantly characterised, intensely felt singing made its mark in a way you'd think impossible without listening to a much more expensive amplifier.

Bass weight was generally fine, drums and plucked double bass projecting powerfully without overwhelming and submerging the rest of the music. Some listeners might wish for a little more weight, in which case NVA's bigger, beefier Statement series could well be the answer. Yes switching to the AP30, having been using some expensive valve amplifiers, I felt the NVA amplifier held its own surprisingly well, sounding both solid, forceful and subtle. Perhaps the sound of the high hat cymbals was not as spine-tingling sumptuous. But for such magic definition you'd need to spend considerably more. Where the AP30 certainly did score was in its ability to grab your attention with the live feel of music. It's that all too rare quality of focus which, once heard in a hi-fi context, cannot be sacrificed.

ALBUM ANALYSIS

Yuri Bashmet: Glinka, Roslavets, Shostakovich Viola Sonatas (BMG Music RCA Red Seal 9026-61273-2) The most intense, controlled, sublimely realised recording of the Shostakovich sonata was powerfully conveyed by the AP30. The balance between viola and piano was convincing and the drama, dynamics, tonal clarity and sense of occasion forcefully projected

Purcelli: Dido & Aeneas Taverner Choir and Players Parrott (BBC MM129)

A difficult disc for any system to reproduce. The soloist and choral sections sounded well delineated with a vibrant, crisp projection. The sense of acoustic space and depth was strong, but somewhat contrived. The amp revealed some of the balance difficulties with this recording without allowing them to intrude too grossly with the enjoyable performance

Greig: Sons Anne Sofe von Otter, Bengt Forsberg (DG 437 521-2)

A stunningly beautiful album, precisely reproduced through the AP30. At times von Otter seemed within the same room as me. Some of the tiny flawed details such as cleared throat and manuscript noise from the piano were also captured, heightening the sense of realism

Abdullah Ibrahim/Africa - Tears and Laughter (Enja 3039 2)

The sense of solidity and weight to the sound of this roughly hewn album, particularly in the track Ishmael, was impressively preserved by the AP30. The intensity of the vocal lines and the drama of the percussion was dramatically realised, though the AP30 did not hide some of the strident qualities of the recording.

TECHNICAL DESIGN

The key to this amplifiers design is its simplicity. From the hard-wired input connections and the use of passive pre-amplification, to the absence of tone controls and filtering, this is about as minimalist an amplifier as you could conceive.

A 100kohm ceramic metal passive volume control is the main component in the passive pre-amplifier. A 10kohm metal film resistor is used with the pot to derive a near logarithmic attenuation logic. The almost total absence of filtering is very unusual. There's no output filer, only a 470pF input capacitor, and tone controls are omitted, on the grounds that NVA believes all these extraneous components and circuits are bound to compromise performance.

NVA's own phono stage can be added to the standard AP30 retrospectively. Alternatively NVA will fit the board during manufacture. As you'd expect, the phono equipped AP30 is slightly more expensive that the line only amp. All the necessary wiring changes and board fitting required to modify from line-only to phono-equipped AP30 are made at NVA's factory.

The amplifiers unusual glued case may not appear an inspired aspect of the design; don't be fooled. The case is an important element in the AP30. NVA discovered that the reason previous products sounded worse than preproduction, bread board equivalents was simply the addition of a production metal case. It turned out that the metal cases stored charge and electromagnetic fields which interacted with the signal-carrying circuits. Hence the use of wooden sides, an aluminum base and acrylic front panel. The power amplifier is designed to deliver high current when required through conventional bipolar output devices. Mains power is fed to a 160VA toroidal transformer closely specified by NVA. Power supply regulation is achieved with the help of conventional 1950s wound paper capacitors.

THE CYBERFI VERDICT

If you like your music up-front and vivid, the NVA AP30 will prove a constant source of delight. It must be partnered with the right cable, preferably NVA's own interconnects and LS1 loudspeaker cable. I was struck by the precision and clarity of sound using the AP30. Its superb focus and sense of rhythmic cohesion is impressive. This is the sort of sound that can practically transport you to the place of the recording. Background listening... forget it. This amplifier demolishes barriers and places you in the front row. If you want musical involvement from a simply configured, well engineered design, the AP30 should be high on your shortlist. Driving suitably responsive, medium to high sensitivity loudspeakers, the AP30 can deliver surprisingly high levels, though careful adjustment of the unusually configured volume control may be necessary.

RIGHT OF REPLY

Richard Dunn, NVA.

What a nice bit of nostalgia, having to reply to a review on one of our products. It's just as we used to do with the sadly missed Audiophile magazine. I use to love replying in that UK magazine, as it gave me a 'soap box' to rant about the political nature and general state of the UK hi-fi industry. CYBERFi is an international magazine on the internet, so I can no longer be so parochial. I am forced to address myself only to the content of the review. Ho hum! I think it would be churlish to criticise the review in any way. It seems to have described the essence and also many of the nuances that make NVA ownership so fascinating to the many worldwide addicts to our brand of musical exploration. I would like to accentuate Johnathan's comments about cable and widen the discussion. There is no such thing a 'the best cable'. Loudspeaker cable should be looked at as part of the amplification system. Just because with your own or with a specific amplifier you have found a cable to be best DO NOT presume that this will hold true with all amplifiers. I have received NVA amplifiers 'blown up' by people who have believed what other manufacturers or their dealers told them. A case in point was one customer who was sold a 10m set of tri-wired cable. The result: one week later the poor amplifier gave up trying to drive a grossly capacitive load. The moral is: a little knowledge is a dangerous thing, especially when acquired by indoctrination.

A second case occurred because a distributor I share with Audio Note in the Far East insisted on using NVA amplification with Audio Note silver cable. Now this is a very fine cable when used with valve (tube) or highly compensated solid state amplifiers, but is lethal when used with non compensated or filtered amplifiers. The moral of this tale: never confuse salesmanship with fact. Please note that there are many cables suitable for use with NVA amplifiers. As a rule of thumb, if you use cable or under 250pF per meter and do not bi-wire or tri-wire, or more importantly use the cable that has been designed for the amplifier, NVA cable, then the benefits and pleasures amply described by Jonathan Kettle in the review will be yours.

WE ARE SO CONFIDENT IN THE QUALITY OF OUR PRODUCTS AND DESIGNS WE OFFER 30 DAY NO QUIBBLE RETURNS POLICY

Available in 120v or 240v please stipulate on purchase

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

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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 FOURTEEN DAYS DEPENDING UPON ORDER PRESSURE

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 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.