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Integrated amplifier

Price: 25 900 zł

Manufacturer: Ayon Audio

Gerhard Hirt | Hart 18 | A-8101 Gratkorn | Austria
tel.: +43 3124 24954 | fax: +43 3124 24955


Country of origin: Austria

WWW: Ayon Audio
Polish language www: Ayon Audio

Text: Marek Dyba
Photographs: Piksel Studio

Spark Delta is one of many new Gerhard Hirt's amplifiers. It's a huge beast weighting over 50 kg! As Gerhard himself explained to me: „if you want to build a good PSE (parallel-single-ended) amplifier with 6C33 tubes the first thing you need are enormous power transformers with lots of headroom, and those, as you might have guessed, weight a lot”. Later he told me also about his new „auto-fixed-bias”. So if you are going to try or buy this amplifier please read the manual before plugging it in – mostly to learn how this auto-fixed-bias works and/or how to operate it. There is a small push-button on the back panel - you need to use it to start the process of testing and setting bias (for each power tube separately). This test is run automatically also if amplifier is on longer than 45 minutes after you turn it off. The reasons are twofold. First of all it allows to find out if any of tubes is faulty (than amplifier will not turn on the next time and proper LED will show you which tube has to be replaced). Secondly only after 45 min of operation tubes reach their optimal working temperature so it makes sense to set bias then so the next time you start your amplifier bias shall be set at optimal level for tubes working in optimal temperature. This way performance should be always best. As Gerhard told me: „6C33s are quite specific tubes – on one hand they deliver fantastic sound but on the other you need to be very careful when using them, as parameters of their work may change and that might be dangerous first for the tube itself and then, as a consequence, also to the whole amplifier. Our new auto-fixed-bias system prevents that from happening – sure a tube may go bad but nothing will happen to the amp. What is also important this system does not affect the performance unlike most „auto-bias” systems used in most tube amplifiers. All you have to do is read and follow the manual – just ran the whole bias testing sequence before the first usage and then each time after tube replacement. Apart from that the whole sequence will be ran each time when you turn off amplifier after minimum 45 minutes of operation because than bias is set for tubes working in their optimal temperature. All that is to make sure that the next time you turn your Spark Delta on bias will be set for optimal performance and at the same time you might be sure that all tubes are fine because otherwise amp would not start at all”.
Well, I personally heard couple of times from some audiophiles that they would never buy a tube amplifier because „tubes will wear off over time, their parameters change over time, you never know if or when they break” etc, etc, and such concerns, even being a tube fan, I can partially understand (although usually it is just an excuse not the real reason). This new Ayon's auto-fixed-bias is an answer for all malcontents – amplifier itself will test tubes, set proper bias and let you know if and which one exactly needs to be replaced. Can it get any easier? Well, OK – you need to run sequence of tests after you replace a tube but it will not happen to often.


Płyty użyte w teście (wybór):

  • Etta James, The Chess Box, Chess Records, B00004TS85, CD.
  • Etta James, Eddie 'Cleanhead' Vinson, Blues in the Night, Vol.1: The Early Show, Fantasy, B000000XDW, CD.
  • Etta James, Eddie 'Cleanhead' Vinson, The Late Show, Fantasy, B000000XE0, CD.
  • Etta James, Seven Year Itch, Polygram Records, B000001FUJ, CD.
  • Renaud Garcia-Fons, Arcoluz, ENJ94782, CD.
  • Renaud Garcia-Fons, Oriental bass, Enja, B000005CD8, CD.
  • Renaud Garcia-Fons, Fuera, Enja, B00002DFOY, CD.
  • The Ray Brown Trio, Soular energy, Pure Audiophile, PA-002 (2), LP.
  • The Ray Brown Trio, Summer Wind, Concord Jazz, CCD-4426, CD.
  • Ray Brown Trio, Live from New York to Tokyo, Concord Jazz, CCD2-2174-2, CD.
  • Arne Domnerus, Antiphone blues, Proprius, PRCD 7744, CD.
  • Carlos Santana, Guitar Heaven, Arista, B003TML0VO, CD.
  • Carlos Santana, Supernatural, Arista, B00000J7J4, CD.
  • Carlos Santana, Shaman, Arista, B00006IR5V, CD.
  • John Lee Hooker, The best of friends, pointblank, 7243 8 46424 26 VPBCD49, CD.
  • AC/DC, Back in black , SONY, B000089RV6, CD.
  • AC/DC, Live, EPIC 510773 2, CD.
  • Keith Jarret, The Koeln Concert; ECM, 1064/65 ST, LP.
  • Beethoven, Symphonie No. 9, Deutsche Grammophon, DG 445 503-2, CD.
  • Holst, The Planets, DECCA, SXL6529, LP.

As I already wrote in one of the recent reviews only very few devices I tested so far were not only very good objectively but I also personally liked them so much that they would have been mine if I only could have afforded them. Among those very few was Ayon Crossfire later replaced by Crossfire II. Both were SETs build around 62B power tubes (that's a more powerful cousin of Western Electric's 300B). They delivered wonderful midrange that came really close to what I love so much about good 300B SETs (like mine ArtAudio or AirTight for example), but coming so close in these area they were capable of delivering enormous portion of dynamics, well extended and articulated bass and wonderful treble. Another important advantage – output power that allowed to dive much more difficult loads than 300B ever could. The only downside (from my point of view) was its/theirs price – absolutely adequate to the performance but not to the depth of my pocket. Most likely if I only could have afforded it Crossfire would have become my reference amplifier even if it meant resigning of small portion of midrange magic (of my 300B SET). Spark Delta is a PSE (parallel single ended) design based on Russian 6C33 tubes (two per channel) delivering 2x35W, which is exactly same output as Crossfire's, which made this (unfortunately indirect) comparison even more interesting.

I would really like putting these two amps side by side and comparing them directly, because only than I could be absolute sure about my preference (I surely have my favorite but direct head-to-head could give me the ultimate certainty). Ups, I did it again – I told you at the beginning I liked this amp…, but on the other hand it wasn't really a surprise (at least for me – a dedicated fan of Gerhard Hirt's SETs and CD players). But let’s not rush things up. All Ayon amplifiers are well build and superbly finished and they weight … a lot. To be honest I really like that characteristic design, period. I think many people feel the same way as there are many owners of products of this Austrian company around the world. Of course there is another explanation – if you manage to bring those damn heavy pieces of equipment to your home for test listening session you simply can't even think about lifting and carrying them again... - a joke obviously, or maybe... (I had to co-carry this 52kg monster up to my fourth floor apartment – that's why I might be a bit grumpy).

When I started my session with Spark Delta I felt a bit … blue, so I started with … blues, Etta James to be exact. And the first day was gone... . Ups, more details? OK. I have quite some recordings of fabulous but bit forgotten Etta, and Spark Delta turned out to be a “heavy weight” SET. The midrange came dangerously close to what I'm used to listening to my WE 300B SET – rich, smooth, warm sound, feeling, emotions, and very palpable image. Etta James stood no more than 3 meters from me. I could look in her eyes, see every face, every gesture that emphasized emotions in her voice, I could clearly see that she put in everything she had – her heart, soul, body and mind. Her voice – dense, sensual, vibrant – it flowed slowly towards me keeping me hypnotized on the couch. Fantastic, spontaneous audience made the whole presentation even more realistic, palpable, almost convincing me that I was also a part of this amazing performance of the great lady of blues and soul. Soundstage was also fantastic and I don't mean precision but rather its size and spaces between musicians that simply “felt real”. There was no huge (and thus false) depth, no instrument was placed 10m from the others – it all felt right. Could I just stop after one album? Nope, so I continued with more and more recordings of this amazing vocalist and I spent with her almost eight hours. After that I realized that I wasn't tired at all – that was surprising – I don't know about you but 8 hours of listening is usually too much for me. This time not only wasn't I tired – I felt great, full of energy. That's one of the advantages of SET amplification - doesn't matter how long you listen to it, you will enjoy it even after many hours of listening. I can't say same thing even about best of the best SS amps, or tube push-pulls for that matter.

Knowing already how good the midrange was I decided to move on and take a closer look at the both frequency range extremes. To find out about Spark Delta's bass performance I chose (of course) double bass recording – two of my favorite bass players to be exact - Ray Brown and Renaud Garcia-Fons. Not only are they fantastic musicians but also most their recordings are of really high quality. Conclusions? Spark Delta seems to deliver rather … „tube-like” bass, meaning there is a lot of it, well extended, rich, colorful with nice rhythm. No downsides? Well, yes but some people might want it to be bit better defined and more taut. Comparing to the long list of upsides it's almost nothing – most people would not even think about it but if you are a fan of very well defined, taut bass Spark Delta won't be your first choice. It all depends on your preferences for both sound you like and music you mostly listen to. Double bass live sounds much like the one delivered by Ayon – decay is quite long as the soundboard is huge. It is bit different when it comes to electronic bass as it might be very short, taut and than a bit longer decay delivered by Spark Delta is not a perfect match. But anyway if you are a fan of electronic music it's quite unlikely you'd buy tube amplifier. Most of Ray Brown's recording were performed by trios and this kind of acoustic performances sound absolutely amazing with Spark Delta. Very tangible, realistic 3D soundstage, tones of precisely delivered details that often tend to disappear, live recordings with clear participation of public – all those things make this performance incredibly involving, realistic, it allows you to forget that you listen “only” to the recording. Recordings of Renaud Garcia-Fons include a lot of different instruments (to be honest I can't even identify all of them) from all around the world. That makes it difficult to tell whether or not the sound of particular instrument is correct but it surely allows to check how well this amplifier differentiates sounds throughout the whole frequency range.

I really enjoyed „Antiphone blues” from Arne Domnerus – that's a “simple” recording of two instruments – saxophone and organ. It was taken in a church so also acoustic environment plays a great role. I really enjoyed this recording as Spark Delta delivered very tangible, vibrant saxophone with wonderful timbre and mighty organ that really made use of Ayon's bass characteristic. I was impressed with this amazingly deep, low tone, really long attack decay and this unmistakable feeling of overwhelming power this instruments gives to the listeners and Spark Delta was able to recreate. As one might have expected from SET the ambiance, reverberations, and huge soundstage were simply amazing. All those elements created extraordinary spectacle with proper solemnity that could only be compared with impressions from some other live concerts.

Acoustic pieces usually sound great on SET amplifiers but not necessarely when it comes to more dynamic, heavier music. Spark Delta had no problem with delivering proper dynamic scale, or rhythm in such recordings starting from John Lee Hooker's electric blues, Carlos Santana's guitar up to heavy rock'n'roll from Australian veterans - AC/DC. An interesting finding – each drummer's strike had a proper strength and weight and there was no sign of this sustained decay which might have suggested that it appeared only in the lowest bass and not in the mid- and upper bass. Each strike was fact, taut and importantly not only decay but also attack sounded right. Regardless of recording electric guitars sounded heavy, even rough when necessary and performance of bass-guitar had proper pace and rhythm. Pieces from AC/DC proved ability of Spark Delta to deliver very nice resolution even in the most dense fragments. Recent Santana's recordings show an influence of “mp3 era” - there is a strong emphasize on the bass range which makes it sound good on mp3 players but if you try to listen to them with a good stereo rig you have to hate this “modern” way of recording making. Anyway Spark Delta didn't try to hide that – the emphasize was obvious so I couldn't really fully enjoy those recordings especially that this bit soft, rounded bass of Ayon didn't help the case at all. On the other hand it proved that Austrian amplifier wasn't one of those that try to hide recordings downsides – if you play a recording that is not so good you can't expect that amp will make some magic and deliver perfect sound. So all you got to do is to use only good recordings and not those made for mp3 fans. As long as you play high quality recordings and hook up well matched speakers (that would not be too difficult loading) you can really enjoy almost any music at all (maybe accept some really heavy stuff).

Large, classical pieces sound quite good but when listening to them I realized that there was quite a significant difference between Spark Delta and Crossfire 2 performance. Spark Delta delivered beautiful midrange similar to what I get from my 300B SET. Crossfire on the other hand offers incredible dynamics and transparency, and shorter, taut bass. These features allow it to present great orchestra in orderly, transparent way, also the scale seems more proper. Please don't misunderstand me – I'm not saying that Spark Delta can't deliver big, classical music in a good way, I simply claim that, if memory serves, Crossfire does it better. Soundstage is more precise, it's easier to follow chosen instrument or group of instruments, distances between instruments are better defined. Beethoven will still sound “big”, dynamic with Spark Delta, timbre will be very nice too but the “big picture” will be more homogenized – it will sound rather like one huge instrument not a complex group of instrument. This way of presentation is quite interesting – that's a conductor's job to create a perfect harmony within all members of the orchestra, right? Spark Delta does its part in this task.

In my ears 6C33 by “Gerhard Hirt” sound more alike 300B, than 62B tube even though the latter is a “cousin” of the most famous triode. So I think that fan of acoustic music and vocal recordings would rather chose Spark Delta, and those who prefer more dynamic, heavier music, also orchestral recordings would probably chose Crossfire. At least I would recommend such choices. Crossfire (especially version 2) seems to be bit more versatile contender, but on the other hand most of us look for an amplifier that plays our favorite music best and not the most versatile one. So most likely (assuming that some potential customer would be considering one of these two amps) final choice would be made upon individual sound/music preference and the level of performance as this is absolutely comparable. Crossfire (first 1 and now 2) is on my short list of “I'd love to have it” and now Spark Delta made it to the list too. These are two wonderful amplifiers, solidly build, beautifully finished, fully capable of delivering amazing performance that brings listener very close to the music. Maybe one day one of them will become part of my rig. I truly hope so.


Spark Delta is a PSE (parallel single ended) integrated tube amplifier, with two Russian 6C33 power tubes per channel. It operates in class A. It is a big brother of our Spark III amp that uses single pair of same power tubes. 2 pieces of 12AU7 and 4 pieces of EL84EH work in input stage and as drivers. Casing looks like typical Ayon – black, with front corners rounded, chrome transformers cans and red backlit logo. There are two nice knobs on front – volume control and input selector. Amplifier is equipped with 3 RCA inputs (very nice ones from WBT), one XLR, and „direct in”. Speaker binding posts (for 4 and 8 Ω) also come from WBT – solid, very nice looking but not the most reliable as their smooth surface makes it quite difficult to get a proper grip when cables with spades are used. Next to the power inlet there is a AC phase polarity control indicator and next to it there is a ground switch that might come handy if any problems with hum appear. There are several cans on top of the amplifier hiding inside powerful transformers necessary to fulfill what Gerhard Hirt described as a must – as good power supply as it gets. Separate power transformers, chokes and filters provide total isolation between the input and output stages. Spark Delta features also regulated DC filament supplies with a soft start (which significantly extends tubes life), and current in-rush limiting. As always Ayon took care of as short signal path as possible (even paths on PCBs are as short as only possible), and there are no solid state elements in signal path. Only carefully selected, premium quality passive components are used in all applications. Amplifier sports remote control – a very nice, handy one that allows user to adjust volume and use “mute” function.

Distribution in Poland: Eter Audio

Eter Audio
ul. Malborska 24
30-646 Kraków

tel./fax: 0048 12 425 51 20/30
tel. kom.: 0048 507 011 858



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