Been meaning to put some words down on my latest acquisition (that is, before my next acquisition arrives which is fairly soon!) - an Audiopax Model 5 preamp.
It’s been a long journey - over six months on the pre specifically - though the larger change started about a year ago when I changed my power amps from the Radford STA100 (100w class AB restored for me by Radford Revival) for some Silvercore 833C monoblocs, dropped in for a listen by G-Point Audio in the UK.
In my opinion the Radford (though it dates from the late 1960s) is about as decent a KT88 PP amp as you’ll get, and works extremely well with moderately inefficient speakers such as vintage Tannoys. But there was something intensely musical about the 20w single ended Silvercores that just turned the musical engagement up several notches for me. (Kedar here has heard them and I think rated the Tannoy HPD -Silvercore combination, also Audiophile Bill has been round).
The Silvercores with my custom Tannoys, built around 12in HPDs drivers in a vintage looking but modern-specified, well braced and damped enclosure with tricked out custom crosssovers, don’t quite have the absolute bottom end grip of the Radford, but excel in just about every other area, not least in their delightful way with air and space, as well as their timbral accuracy with acoustic instruments. For my main diet of baroque, renaissance and early classical chamber, vocal and solo instrumental music, plus 19c Lieder and an increasing amount of jazz, it’s hard to imagine much better.
However the Silvercores’ new transparency raised a niggling doubt about my preamp - an EAR 912 - to a higher level. This is a preamp I still rate highly - at least as a phono stage - and which at that time I’d owned for about four years. In my view the phono stage in the EAR 912 - an LCR type which uses inductors in the RIAA conversion, alongside three tubes in the phono stage and a pair in the output stage - is one of the finest out there at least at sensible-ish money. It’s unique to the EAR 912 - the phono circuit in the EAR PB88 stand-alone phone stage and the similar one in the EAR 868 phono preamp are different, using two tubes and a FET alongside the inductors.
As a fully-featured phono preamp with a unique four-option super quiet built-in step-up transformer (similar but subtly different in its ratios to the stand alone EAR MC4), together with an interstage section for gain matching, mono button, tape loops, VU meters, and all fully balanced, it’s about as comprehensively equipped as you can reasonably expect. It replaced an Aurorasound Vida + Modwright 36.5 in my setup, and I found it even held its own against dedicated stand alone phono stages without preamp sections of similar sort of value (that is, the £10k GBP mark). So the line stage is kind of ‘free’.
In my last year or so with, though, I found I had stopped using all the features - starting with bypassing the internal SUTs using external Miyajima ETR-Stereo and ETR-Mono SUTs respectively. These are primarily known for their flexibility, with the mono one having 11 possible narrowly-spaced ratio settings from 1:9 to 1:45, and the stereo one having an incredible 16 possible ratio settings from 1:4 to 1:100. This is achieved by having four taps on the primary and four taps on the secondary, independently adjustable. Both mono and stereo also have four loading options (to provide further trimming for better matching with the phono stage), while the stereo one also has variable capacitance - not common in the MC world but effective in taming some cartridges with high frequency lift. Both are also bypassable if you want to use a MM cartridge. These proved a pretty major upgrade on the EAR internals.
I then started to experiment with separate components - and found that while the phono stage in the EAR remained hard to beat, the line section was indeed a relative weak spot. I tried out quite a few line stages including ones from Grandinote (solid state), Audio Research Ref 3, and the matching Silvercore preamp. All of these were very good indeed (as you’d expect), but then I hit on a second hand Audiopax Model 5 preamp, from Brazil. This was a very early version dating back to 2004, and while it was a bit flaky - a channel kept cutting out and it had a very noisy PSU (that PSU was later completely superseded), and it clearly needed some attention, I really liked what it was doing when it came on song. It uses FETs rather than tubes, but you’d never tell from the sound which was as harmonically rich as you’d ever want and never etched or stark in the manner of a lot of solid state preamps, or passives of the various stripes. Rather it brought with it a really nice way with detail and a delightfully impressive ability with space and 3D-ness. I felt it allowed the Silvercores to bloom and perform to their full potential - the synergy I was getting was very surprising. Going back to using the EAR line stage was far from shabby, but lacked the musical insight I was getting from the Audiopax.
Anyway, the flaky old Audiopax reluctantly went back went back to its owner, and I focused on finding a phono stage that would improve on the EAR - eventually settling on the Allnic H7000V. The phono stage selection is quite another story for another time (I had the Munich show in between which was consumed by my search for a stand-alone LCR phono and I think I've contributed some impressions here before). But after after that arrived, and especially after I swapped out its stock Chinese rectifier first for a vintage RCA and later for a fancy KR one, it made no sense just to keep the EAR just as a linestage. I sold it and placed an order for a new, custom built Audiopax Model 5 from Brazil. Features from the previous Special Edition had been rolled into the fourth generation version, but I decided I wanted fully balanced - two balanced inputs and output - which meant a custom build including chassis modification.
Audiopax is not a hugely-known brand at least in Europe, but it has had a bit of attention at different times in its history I’m not going to repeat the stuff online about it (which is worth a read - I've put some links below) but the Model 5 dates back to the early 2000s and was Audiopax’s second big product after the breakthrough one, their Model 88 mononoblocks. Both pre and mono blocks have a feature entitled timbre lock, which seems to use differently-tuned gain stages in series to enable the characteristics of the output to be tweaked. This isn’t a tone control, but rather something that changes the nature of the sound that’s produced. For the monoblocks it’s primarily aimed (it appears) at tuning the amplifier sound to match the speakers; for the preamp, the goal is to match the preamp and power amp.
Reading the various blurbs I was skeptical but in fact in use it’s fairly intuitive and quite easy to determine what sounds ‘right’ (in my opinion). One the reviews calls it a ‘gestalt changer’ and I’d pretty much agree with that - used with solid state amps, you increase the values on the timbre lock and you get a more musical, open, single ended-type sound. Single ended valve amps need much lower numbers as this doesn't need to be dialled, in; push pull valves generally something in the middle.
In between my order and the Model 5’s arrival, I was loaned an Audiopax Maggiore L50 by the UK distributor, Audio Reference. I was a bit nervous about this - compared to the ‘Classic’ Model 5, the L50 was a massive upgrade - in addition to the vintage model’s way with timbre and detail, it has a truly wonderful, full, very large, 3D spacious sound, bags of detail, rock solid bass (producing tight, prodigious bass I was surprised that my Silvercores were capable of) and a lovely feeling of quality in how it operated. It was also dead quiet. What if my Model 5 was a let down compared to this £16k GBP slice of magic (over twice the price of the Model 5)?
In the end, the gamble paid off. What I ordered was generation four of the Model 5, which has been out for a few years. But Audiopax are on the cusp of releasing generation five, and what arrived was a kind of 4.5 version that already incorporates most of the changes soon to formally come in the new model. The Model 5 as received didn’t have quite the massive scale of the L50 (its power supply is similar sized but notably lighter, though still pretty chunky), but it seemed to have more detail, more intimacy, and was nicely scaled for my listening room, and also (very welcome this) was just as solid in the bass as the L50. Word came back that the L50 is up imminently for similar updates, to the point that my Model 5 does indeed leapfrog its big brother in several aspects, at least temporarily - so it seems my feeling of a general improvement over the L50 was not just my imagination. Anyway, I’ve been utterly delighted with it.
I am going to have to hear the Model 88 monoblocks at some point - that will be an interesting comparison with the Silvercores. But for now I'm happy.
A few links for further info:
https://6moons.com/audioreviews/audiopax4/model5.html
http://6moons.com/audioreviews2/audiopax/1.html
http://www.audiopax.com/e/Model5.html
http://highfidelity.pl/@main-628&lang=en
http://www.enjoythemusic.com/magazine/equipment/0102/audiopax88.htm
I was the first UK owner of the original Model5 pre. It’s superb. Congrats on your choice. Eduardo,God rest his soul, was a genius.
