In short words, because it is one of the best amplifiers after modifications! The EL86 is a modified EL84 with a low impedance output, designed for OTL (~800Ohm) operation. The purely OTL AG9014 was upgraded with a transformer at the AG9015 which had to bridge just a smaller difference in the impedance (800Ohm to 8Ohm), so this is one of the reasons for the great sound. Then there are the legendary Miniwatt tubes from Holland + the legendary Philips mustard capacitors + the Philips electrolytes which are sometimes in a condition better than new (see blog feed for cap measurements). There is no overall negative feedback, just some local which is good. Also the circuit is an SEPP (Single ended Push Pull), which is nowdays by ETF members rediscovered super circuit. (This is NOT SE, NOT PP, neither Ultralinear!)

How did I realized what a legendary great amp we talk about?

In 2018 – as in many other years – I visited the Klangbilder High End fair in Vienna. In one of the rooms, I saw a demonstration with Dr. Simon audio products ( Nahfeldmonitor with a so-called “Bionisches” preamplifier https://somu-auko.eu/unsereproduktezurmusikwiedergabe.html

(Alte links: https://www.klangbilder.at/de/aussteller/2018/somu_auko/ http://www.liverecordings.com/highendaudio/index_p3.html )

They did not have any amplifier to offer so they used a Philips AG9015 to demonstrate their loudspeaker and riaa preamp.

The sound I heard at this room was amazing! I am mostly very tired with good sounding systems, which is like a sound with “demo” mode on (too much highs, too much bass, so like the tv picture with demo on at the shop, which you would never use at home) This is very attarctive for first, for a 3 minute catchy demo, but very tiring after some minutes, not to speak about how to live with such. But this sound was so different, so natural, flowing like a charm, has everyithing so exactly how I was always hoping, AND not tiring (well this is not true, as later it turned out it is really tiring to not sleep till 04:00am, because vinyl after vinyl which can’t stop with). I decided to buy the loudspeaker + the amp. The amp was relatively easy to get, can be sourced for 200-600EUR, but the speaker what I heard at Klangbild was more then 7kEUR (much more), so a clear “no go” for my budget. (and many people were sure Manger speakers create more troubles then they resolve… Dr.Simone NSW is an high priced better built Zerobox 109, but with 8 Ohm… While 8Ohm is a must due to the Philips transformer, so Zerobox 109 was also not an option.)

So I had just the little Philips Ag9015 with some bad old Hungarian 8Ohm Videoton (used in garage today) speakers from my childhood. The Videotons sounded far better then earlier ever, but somehow with the feeling that the real sound is still behind a barrier which I have to remove. Well I managed to destroy this wall and release step by step the music and have the amp what I was always was looking for. The amp works now with a Tannoy Monitor Gold 12″ Chattsworth, which perfect match pair and fulfills all my dreams after so many years of search. Please join me and let me explain what you need to modify in the Philips AG9015 to make it one of the best amp. An amp what proudly can be shown at any High End fair to convince open minded listeners.
By the way: When I talk about the AG9015, then all statement matches to AG9018, which is equivalent, except it has nice wooden housing.

Please click the page through (level 1, 2,… components to use, ect) to understand what to tune, how to dig out the extreemely nice sound from this amplifier.

The first 2 pic from Vienna Klangbilder 2018: