ON TEST avm inspiration p1.2 phono stage AVM s CEO, Udo Besser, refers to it as our smallest guy, while others within AVM call it our newest baby, but what they re all talking about is this German company s latest phono stage, the AVM Inspiration P1.2. As with all phono stages, the purpose of the AVM P1.2 is three-fold: to boost the low voltage from a moving-magnet or moving-coil cartridge to a level that s highenough to drive a pre-amplifier; to provide an appropriate load for that cartridge, so it performs as its designers intended; and to provide RIAA equalisation to correct the music signal recorded on vinyl LPs. Why do you have to correct the signal recorded on the LP? Basically, in order to be able to engrave an audio signal on an LP, the mastering engineer has to dramatically reduce the level of the bass frequencies (gradually from 1kHz until by 20Hz the level has been reduced by 19.27dB) and dramatically increase the level of the high frequencies (gradually from 1kHz until by 20kHz the signal level is boosted by 19.62dB). If this were not to happen, the groove would meander so violently at low frequencies that it would, literally, throw the cartridge out of the groove, while at high frequencies, the sound caused by the stylus scraping over the vinyl would drown out the treble. (This is a somewhat simplified explanation, but an exploration of the effects of the constant velocity characteristics of magnetic cutter heads is, I think, somewhat beyond the requirements of this review.) So it s the job of the phono preamplifier to boost the level of the bass back to where it s supposed to be, and reduce the level of treble, via a process known as equalisation. The equalisation curve that s used nowadays to perform this function is known as the RIAA equalisation curve simply because it was developed by the Record Industry Association of America. Before the RIAA stepped in, different LP manufacturers used different curves, so if you played an LP pressed by Columbia you d need one curve, then if you played one pressed by Decca, a different curve and then, if you played one by Deutsche Grammophon, another completely different curve again. In fact, at one stage, there were more than 20 different equalisation curves in common use, which was obviously a nightmare for both consumers and manufacturers alike. Even as late as the 1970s, some manufacturers refused to use the RIAA-specified curve, which is why some phono stage manufacturers still produce phono stages with switchable equalisation (usually between the RIAA, Columbia, Decca, CCIR, and Teldec EQ curves). The Equipment In typical AVM fashion, the Inspiration P1.2 (which offers only RIAA-standard equalisation) is beautifully crafted from solid brushed aluminium and the front panel is an exercise in minimalism: there s just an AVM logo and a small LED that glows when the unit is switched on. In order to keep the noisy 240V a.c. mains power supply away from the phono circuitry, AVM supplies a plug-pack 32
that converts the 240V a.c. to 24V d.c. and it s this d.c. voltage that is plugged into the rear of the P1.2 using a standard 3mm d.c. plug (tip positive). A power button is located alongside the d.c. input but note that it s not a mains power button: it just disconnects the d.c. from the AVM s rails. Although the AVM doesn t draws much power when it s operating (3.4-watts, according to the At one stage, there were more than 20 different equalisation curves in common use, which was obviously a nightmare for consumers manual), I d still recommend switching it off when you re not using it. Switch it off first by using the power switch on the rear panel, and then by switching off the 240V supply to the plug-pack. (Similarly, when switching on, switch the plug-pack on first, and the power switch on the AVM second.) The AVM P1.2 has two inputs: one for moving-magnet cartridges; the other for moving-coil cartridges. Both use gold-plated RCA sockets. Some early AVM manuals and brochures say the AVM P1.2 has three inputs. This is incorrect. What looks to be a third input on the rear panel is actually a socket that allows you to plug in external loads to modify the input impedance of the moving coil input. AVM provides three standard loads for you, 100Ω, 200Ω and 1kΩ, with the resistance wired inside a standard phono plug (see photo page 36). When plugged in, the resistance is paralleled with the AVM P1.2 s internal resistance of 47kΩ. This means that with no plug fitted, the MC input s impedance is 47kΩ. With the 1kΩ plug it s changed to 979Ω. With the 200Ω plug it becomes 199Ω and with the 100Ω plug it becomes 99Ω. (There are two plugs, one for each channel, and you always need to use BOTH plugs, which also must be the same resistance). Although AVM s plugs cover the most common impedances, if your cartridge requires, say, an impedance of 150Ω, you could easily create this load yourself by wiring a 150Ω resistor across a phono plug, and using that instead of AVM s loads. (You d need to make two plugs, of course!) I was disappointed that AVM s manual offers no advice at all about impedance matching, or even how to use its impedance-matching plugs in fact it doesn t even mention the plugs at all! Nor is there any advice as to how to make your own loads. I am advised that these oversights will be rectified, but that their omission was apparently in part because AVM expects that its dealers should be responsible for providing this information to their customers. Switching between the MM and MC cartridges is accomplished via a small pushbutton that s mounted on the rear panel immediately below a ground terminal post. Mounting the power and cartridge selection switches on the rear panel keeps the front panel neat and clean-looking, but it is a tad inconvenient but only a tad, since the AVM P1.2 is so small 150 120 45mm (WDH) that it s actually very easy to reach behind and switch them as necessary. In Use and Listening Sessions First-up, I have to say how pleased I was that the AVM P1.2 has both moving-magnet and moving-coil inputs, because it means I was In typical AVM fashion, the Inspiration P1.2 is beautifully crafted from solid brushed aluminium and the front panel is an exercise in minimalism: there s just an AVM logo and a small LED. The same could be said of the internal circuitry. able to connect both my tonearms at the same time. Yep, I have two arms fitted to my turntable, because, as a reviewer, I figure that this is the only real way to compare phono cartridges when doing A B listening sessions. However, I also do it from a practical point of view, because when I am not listening critically, I use the arm fitted with the moving-magnet cartridge (which has an easily-replaceable stylus), but when I am listening critically (such as when I am writing a review of an album, for example), I use the tonearm fitted with the moving-coil cartridge. (As you ve probably guessed, some phono preamplifiers have just a single input that serves for both MM and MC inputs, with a switch to select which one you want. This configuration means that if you re running two cartridges, you have to physically swap over phono leads every time you change from one to the other, which is obviously a real nuisance.) I listened first via the moving-magnet input and very much liked what I heard from the get-go. I first heard the gorgeous sound of vinyl: that sweet, smooth, incredibly life-like and natural organic sound that eludes all the digital formats including the hi-res digital formats! But then I heard more the stereo imaging ability of the AVM P1.2 is phenomenally good. Not only was I truly immersed in the musical soundfield, I was embedded in it, so as I swayed and moved my head (I find it impossible not to start dancing in my listening chair when I m listening to vinyl), none of the imaging collapsed or altered: only my perception of it changed to reflect my 33
ON TEST LAB REPORT Laboratory Test Results physical movement in space. Listening to the Sony Legacy remaster of Simon and Garfunkel s Concert in Central Park I was struck by both the superb clarity and richness of their voices, and perhaps made a little sad that although both their voices are still good, their (individual) more recent albums show that age has certainly wearied their vocal cords. If you weren t around in the 80s to hear Simon & Garfunkel at their very best, this is the album that most accurately delivers what they really sounded like, including the incredible harmonies, which are so tonally dense. Because this was New York, they also played their best material for this concert, so every song on this two LP set (180g virgin vinyl) is a classic think America, Fifty Ways to Leave Your Lover, Sounds of Silence, April Come She Will Switching to the moving-coil input, I used my Kontrapunkt B (with AVM s 200Ω load) to audition Jim Hall s Concierto, using the new double-disc re-release on Pure Pleasure. The sound of Ron Carter s double-bass had me open-mouthed from the outset: such depth, such a stringy tone to the sound, yet delivered with a warmth that eludes digital formats, whether on disc or on file. Paul Desmond s sound, immediately recognisable as one of the most distinctive alto sax sounds I ve ever heard, was partly because of his superbly melodic style, and partly because of his choice of sax (a Selmer Super Action). Like me, Desmond was a huge fan of T.S. Eliot s poetry and once remarked to Dave Brubeck, when he saw a former girlfriend on the street with another man: There she goes, not with a whim but a banker. (Referencing the lines in T.S. Eliot s poem The Hollow Men: This is the way the world ends/not with a bang but a whimper. ) Funnily enough, I am not totally convinced by Jim Hall s version of Rodrigo s Concierto de Aranjuez that gives this LP its title, but all the other tracks are superb, and with a line-up that also has Chet Baker on trumpet, Roland Hanna on piano and Steve Gadd on drums, this is another must-own LP. The sound using the AVM P1.2 was again superb, this time in particular the sound of Gadd s kit, from kickdrum to cymbals, which I think might also be partly due to the sympathetic acoustic of Van Gelder s Englewood Cliffs studio, where this album was recorded, which was noted for its 13-metre-high ceilings. Conclusion You can certainly pay more for a phono preamp than AVM is asking for its Inspiration P1.2 phono stage, but any premium you pay will only get you a larger and more impressive chassis, a front panel full of buttons and flashing lights, and perhaps the ability to switch in pre-made cartridge loads, rather than having to manually fit your own. But the extra money you pay won t buy you any more tonal accuracy, or higher-quality sound. This is one sweet little phono stage. Aaron Perkins Readers interested in a full technical appraisal of the performance of the AVM Inspiration P1.2 Phono Stage should continue on and read the LABORATORY REPORT published on the following pages. contact details Brand: AVM Model: Inspiration P1.2 Category: Phono Stage RRP: $1,249 Warranty: Three Years Distributor: National Audio Group Address: Level 1, 585 Burwood Road Hawthorn VIC 3142 T2: (03) 9230 2088 E: info@nationalaudiogroup.com.au W: www.nationalaudiogroup.com.au Compact case Glorious soundstage MC load adjustment Instruction manual Rear-mount controls The frequency response of AVM s P1.2 phono stage is shown in Graph 1. As you can see, it s outstandingly good, being almost perfectly flat across the majority of the audio band. You can see that from 50Hz to 2kHz it essentially tracks the 0dB reference: that is, 50Hz to 2kHz ±0dB (ignore the little wiggles between 50Hz and 100Hz, it s just a little mains hum that s crept into the measurement). Below 50Hz, the response rolls off to be just 0.08dB down at 20Hz, 0.5dB down at 9Hz and 1.75dB down at 5Hz. Above 2kHz, the response rises very gradually to be +0.17dB at 20kHz and +0.24dB at 40kHz. Overall, Newport Test Labs measured the AVM P1.2 s frequency response as 10Hz to 50kHz ± 0.7dB. The AVM P1.2 s RIAA equalisation curve is shown in Graph 2. Despite this supposedly being a standard there are actually several different versions of it, the most commonly-used one being the IEC-RIAA version proposed in 1976 (and subsequently withdrawn in 2009) but it appears that AVM is using the originally proposed RIAA curve but with a little added boost below 80Hz. measured channel separation at 1kHz as an excellent 68dB far more than will ever be required and channel balance was near-perfect, at just 0.02dB. Inter-channel phase error at this frequency was an outstandingly good 0.03. Overall THD+N was measured as being 0.05%, with a spectrum analysis of the distortion spectra shown in Graph 3. You can see that the second harmonic component is at 102dB (07%) and there s a third harmonic at 115dB (01%). You can see from this graph that the noise floor of the AVM P1.2 is more than 120dB down above 4kHz, and more than 100dB down across most of the audio band. It s only at very low frequencies that the noise floor starts to diminish. However, the A-weighted signal-to-noise ratios measured by Newport Test Labs were excellent, with the laboratory reporting S/N at 78dB A-weighted for the moving-magnet input, and at 64dB A-weighted for the moving-coil input. 34
LAB REPORT dbr 3.00 2.50 2.00 1.50 These don t quite tally with AVL s specifications (86dB for the MM input and 72dB for the MC input) but it s likely AVL was using a higher reference voltage than Newport Test Labs, which would easily account for the discrepancy. Input sensitivity was measured at 5mV for a 500mV output using the moving-magnet input and 0.5dB for the same output voltage using the moving-coil input, equating to gain of 40dB for the moving-magnet circuit and 60dB for the moving-coil input, exactly as specified by AVL. Figure 1. Frequency response of MM input at an output of 500mV. [AVM P1.2 Phono Stage] 1.00 0.50-0.50-1.00-1.50-2.00-2.50-3.00 1 Hz 10 100 1000 Graph 1: Frequency response of MM input at an output of 500mV. [AVM P1.2 Phono Stage] dbr 3 25.00 2 Figure 2. RIAA Curve of MM input at an output of 500mV. [AVM P1.2 Phono Stage] 15.00 1 5.00-5.00-1 -15.00-2 -25.00-3 10 1 Hz 1000 100 Graph 2: RIAA Curve of MM input at an output of 500mV. [AVM P1.2 Phono Stage] dbfs -2-4 One of the three pairs of loading plugs that come supplied free with the AVM Inspiration P1.2. Figure 3. THD+N at 1kHz at an output of 500mV. [AVM P1.2 Phono Stage] -6-8 -10 Overload voltage was measured at 62.3mV for the moving-magnet input and 6.23mV for the moving-coil input, figures that put the AVL s maximum output voltage at a hefty 6.23 volts. These are also excellent figures in themselves, resulting in a phono overload margin of 22dB. Power consumption was measured at 3.58-watts, which is fractionally higher than AVM s 3.4-watt spec, but it s academic, because it s way too low to have any impact on your electricity bill! Overall, the AVM Inspiration P1.2 phono stage performed perfectly on Newport Test Labs test bench, such that, so long as you use the correct cartridge loading plug, it will be completely compatible with all moving-magnet and moving-coil cartridges, and also completely compatible with all following electronics (pre-amps or integrated amplifiers). Steve Holding Outstanding performance! Readers should note that the results mentioned in the report, tabulated in performance charts and/or displayed using graphs and/or photographs should be construed as applying only to the specific sample tested. 36-12 -14 Hz 400 800 1200 1600 2000 Graph 3: THD+N at 1kHz at an output of 500mV. [AVM P1.2 Phono Stage] Laboratory Test Results Test Measured Result Units/Comment Frequency Response @ 1 volt o/p 20Hz 20kHz ± 0.2dB Frequency Response @ 1 volt o/p 10Hz 50kHz 1.55dB Channel Separation Channel Balance Interchannel Phase THD+N 68dB 0.02dB 0.29 / 0.03 / 0.31 0.05% db degrees ( 20Hz / 1kHz / 20kHz) @ 500mV out Signal-to-Noise Moving Magnet 65dB / 78dB unweighted/a-weighted Signal-to-Noise Moving Coil 47dB / 64dB unweighted/a-weighted Input Sensitivity Moving Magnet 5.0mV for 500mV output Input Sensitivity Moving Coil 0.5mV for 500mV output Maximum Input Moving Magnet 62.3mV Maximum Input Moving Coil 6.23mV Maximum Output Voltage Gain Power Consumption Mains Voltage Variation during Test 6.23V 40dB/60dB 3.58 239 248 (MM/MC) watts Minimum Maximum
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