Audiopax 88 - Tubes experimented with?

I know this is well after the initial inquiry. It's now April 2005 and I have a new pair of Audiopax 88 mono amps. The pair was supplied with Sovtek KT88s and RAM 12AT7s. Look, the amps are a little cold, analytical and ragged brand new. The break-in curve is pretty steep though after the first 10 hours or so. A change to Cardas capacitors has made patience on break-in more essential to your satisfaction. I am now well into that steep improvement curve where sound is noticeably better by the hour.

The Russian tubes are clean but bone-dry. I have a stash of circa 1980 NOS British Gold Lion Kt88s which are magnificent in this amp or any other KT88 device, but I am also getting spectacular results and clear improvement over the stock tubes from a matched quad of Tesla Vrosovic KT88s (the maker of the KR KT88 from a few years ago). They are nearly indistiguishable from the Gold Lions. I also have noticed very strong transient clarity and definition from the Ei Type III KT90. With all these tubes, the key is finding the right differential between the timber-lock controls.

For input tubes, the RAM 12AT7s, while not bad, are clearly bested by a set of NOS RCA 12AT7s I am using now.

These amps are sensitive to tube rolling, but frankly nothing sounds bad in them.

Phil

Tao
Can ya buy a pair for me too? You'll have afriend for LIFE!

Hi there folks

My case is the Stereo 88 with custom speakers by Audiopax`s creator Eduardo de Lima. And I have to agree - amazing sound, transient is just amazing and body is just incredible.

Lets go to my experiments

I specially considered "analtitic sound vs euphonic (musical) sound"
I personaly like transparency and not too much color over the sound as audiopax is "what it plays is what it gets".

KT 88 Sovtek: I would say its a good low-cost alternative - they dont have that extention (lo and high) but still are warm sounding and very musical (a bit too much for me with the mids feeling a bit too present). Soundstage is very good but doesnt beat other valves - speacially when about microdinamic elements/reverberations.

KT88 Tesla 187: Not so different from the Sovtek but a lot more expensive (at least here in Brazil). Little more clean hghs.

KT88 Svetlana: My favourites yet - They provide great clean sound, highs and lows are very clean - compared to the sovtek it provides so much better soundstage here (specially the feeling of "size" for the instrumments is way better).
Feels like they drive the audiopax and still have some redroom.

KT88 JJ: A bit too analitic for me - dryer but still clean, very good if you like fast sounding, but the mids will stay where they are. Lows and highs (specially lows) are very rich.

12AT/12AT7
GE Less extention, more body - great for female voices and pianos great reverberation and ambience feel. Those are probably the warmest sounding for those who like older recordings (50s to 65s).

EH Cheap, balanced & precise - as i said above im more of a transparent listenner, so those are the ones im taking yet. Also those are Eduardo's favourites and i bet he has done some testing :)

PHILIPS (dont go for JAN, those are for militry usage - this is for 12AT - there are incredible JAN for other models)
Sound is a bit metalized - hard, i wouldnt recommend.

ECC85 is alternative to 12AT (they are the same but you can find some different looking ones)

Im about to try my first set of ECC85EH but still they should sound the same as the 12AT i already use.

Please let me know what you have over there and how does it sound

But still, Audiopax just sounds good, any valve yet sounded amazing - i just love this thing :)