2. amps-preamps
  3. 191451-185418

NOS Tube Recommendation for Quicksilver Phono Pre Amp

I recently upgraded from the onboard phono stage in my Technics 1500SL to an all tube Quicksilver Phono Pre Amp. I’m about half way through the 30 hour recommended break-in period and so far, there is a lot to like about this piece of gear: Much thicker/more pronounced bottom end (I’ve had to readjust the gain on my subs quite a bit) and much wider/more defined sound stage. However, because I’m also running an all tube integrated amp (Raven Audio Osprey), there is now a very noticeable "warm" coloration to the music that wasn’t there before. I don’t want to give up on my new phono stage, but it’s like I’m listening to music with a wool blanket over my speakers. I’m thinking rolling the tubes to something a little cleaner/brighter could give me the best of all worlds. There are 3 tubes in the circuit topology: 2 12AX7s (one input, one gain) and 1 12AT7 (cathode follower). I’m currently considering a matched pair of Raytheon JRP black plate 12AX7s and either an RCA or Telefunken for the cathode follower (all NOS). Any and all suggestions/inputs are very much appreciated! P.S. my speakers are Raven Audio Corvus Reference Monitors and my current cart is the always amazing Nagaoka MP-500.

crawfishdaddi

Showing 5 responses by cey

cey's avatar
cey
295 posts
 

ask dave thomson at raven audio he also has a lot of NOS tubes for sale. 

your phono amp may not be a good match for the integrated you have. 

pass on mullard,  brinar, amperex/philips and tungsram seem the wrong direction

for your qicksilver.

the raytehon iblack plate s worth a try. 

if you want to spend a lot money, get mazda nickel plate; if you want to spend not as much, get telefunken smooth plate. RCA blackplate have good upper frequency extension as well 

go ahead and start with the top dealer in the US, brnt jessee. hes not the cheapest but not the most expensive, neither. or check with dave thomson at raven audio hes welll-educated on the matter.  

cey's avatar
cey
295 posts
 

@skiznfliz & @crawfishdaddi 5751 are not a drop-in substitute for 12AX7--thats circuit-dependent, and a phono circuit theyre almost never a substifute for 12AX7. quicksilver will tell you if 5751 can sub for 12AX7 in their phono stage. 

cey's avatar
cey
295 posts
 

most tube enthusiasts dont know enough to know that that is incorrect, @crawfishdaddi. 

to be clear, 5751 is not a drop-in substitute for 12AX7 . that particular substitution is circuit-dependent. its rarely the case in a phono circuit.

glad to clear that up.

ceylon

cey's avatar
cey
295 posts
 

@larryi 5751 and 12AX7 specs differently in a few significant ways. gain is one of them. heater current, plate resistance are 2 others. 


@crawfishdaddi 5751 is not a drop-in substitute for 12AX7, especially not in phono circuit. any such substitutions are circuit-dependent. ask quicksilver if such a substitution is ok in their circuit.

 

cey's avatar
cey
295 posts
 

 

@onhwy61 gain (mu) is one of the differnces. there are more, and all are significant. 5751 is not a drop-in substitute for 12AX7. they are not interhangeable. any such substitutions are circuit dependent. check with the builder, manufacturer, designer to find out what substitutions are ok. 

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