Vintage preamp tube 12ax7- 5751 tone trial sound perceptions

thickwood

New member
So many great sounding old 12ax7 tubes no particular tube is best in all amps except perhaps RCA long black plate 12ax7 tube !
In the amps that have preamp gain breakup that is what I call the overdrive tube socket.
In short as I can describe them.

The RCA ax7 Black plate or Bp tubes do not crunch but have the best natural harmonics of midrange ever made.
Your amps EQ 12ax7 might need to have ample highs to push the RCA Bp tube.
Next similar but a thicker OD sound is the Sylvania 12ax7 Bp tube which has more highs slightly more Richie Blackmore sounding.
Tungsram 12ax7 is magical sounding but no crunchy mess just pure pushed sustain sound so much sweeter than any tube ever !
Not a bad note will it do pushed.
Old Mullard ax7 is very good on breakup and nice rounder notes with moderate highs .
Japan long grey plate 12ax7 is more focused that a Mullard with detail and highs not a great overdrive tube but EQ or recovery socket is recommended or FX loop tube ! {made on the Blackburn mullard equipment}
The GE horseshoe getter long plate ax7 has great tones in a dark or muddy amp , it rocks with modern focused sustain & breakup.
Surprised as hell by mistake buying a Telefunken ridge plate 12ax7, the seller thought it a GE ax7 ? wow what a Marshall breakup and crunching with awesome full range harmonics and the most gain of any 12ax7 I ever had wow its good in the Egnater Rebel 30 OD socket. Not for bright amps perhaps
Ei Yugoslavian 12ax7 great deep crunch with great gain in heads , combos my shake them into malfunctions. great tube
The GE 5751 is made for thin bright focused sounding amps , making a deeper warm and good breakup with recessed highs .
Can be a muddy sound in warmer amps.
Honorable mention to currently made Sovtek 12ax7 long plate LPS tube for phase inverter perfection. This tube is a must for overdriven amps in the PI socket no contest !

I found horrible texture in the tone of all new production 12ax7 tubes except the Tungsol 12ax7 RI has decent breakup and depth pushed , but funny I bought one with higher gain than normal and it stayed clean at higher gain setting but was loud as heck !

Raytheon-Sylvania grey plate - old Ken Rad and tungsol- amperex -Holland made ax7 tube and others may be worth bidding on but its hit and miss on tone except Sylvania long grey plate 12ax7 is must for a reference of gain and just nice tone breakup varies but usually not the best !
Your amp and your idea of tone you prefer is waiting for the right tubes which re-voices the amp to work for you and not holding you back !
I found user reviews useless and bought over time too many vintage 12ax7 !
I wanted the best sound possible , but when you crank the power tubes up its a different gain and each amp needs a different EQ and recovery tube for the bass and highs to be great !

Just passing along some tube trials taught me , my effects loop send and return on the Rebel 30 was smearing the highs and needed a warm tube there .
I found that by accidently changing tube there, night and day difference.
My currently made preamp tubes are sitting in a case unused ! except the Sovtek 12ax7 Lps tubes I use for PI sockets !
 
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