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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
crawfishdaddi OP
35 posts
 

@yogiboy - yep, sure did. 

@cey - great thought... text has been sent!

@russ69 - good to know there are high quality new production tubes out there as an option; the NOS tubes are getting rarer and WAYY too expensive!

@skiznfliz - you're the second person to suggest subbing in 5751s for the 12AX7s and I'm intrigued. I will definitely experiment with this!! Also, I started with the MP-200 and it is an AMAZING cart. It is definitely the sweet spot on the graph of performance vs cost. Upgrading to the MP-500 (before I started running the QS phono stage) was the best sound I've ever gotten out of my system. I was MC cart curious, but now I'm most likely MP-500 for life!!

Finally, if you want to save SERIOUS $$$, order your Nag direct from Japan (https://www.cdjapan.co.jp/product/NEONAG-MP-200). I bought my mp-500 this way and had zero issues. 

inagroove
122 posts
 

When I needed to replace the tubes in my Phono Preamp, I called the manufacturer, Zesto.  Fortunately, they are a small to mid-sized manufacture and the owner/designer/salesman, George, is a wonderful guy who loves to speak with audiophiles.  

He told me that he listened to many new and several NOS sets of tubes when voicing my Andros 1.2.  His choice for the 'Best Sounding' tube was current production (and inexpensive) JJs gold.

You may want to contact your gear's manufacturer... like George at Zesto, they probably have done their homework!

@ larryi, thanks for the information on Tele-fakes. Perhaps this is why so many folks are reporting that modern-production tubes, of various brands, sound as-good or better-than NOS tubes.

cey's avatar
cey
275 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. 

crawfishdaddi OP
35 posts
 

Good thought @cey , I ran a quick search of Audiogon and found this:

https://forum.audiogon.com/posts/2446823
 

sounds like 5751s are interchangeable, but I’ll follow up a with a call tomorrow. 

cey's avatar
cey
275 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

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