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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
38 posts
 

@larryi , I'm embarrassed that I didn't know this (I only upgraded from a vintage console ~1 year ago, so I'm still steep on the learning curve). The worst part is, my TT is only ~2 ft from the phono stage on the same rack! I was using that ridiculously long cable (originally bought for my R2R which is across the room) because the cable I ordered specifically for my new QS phono stage hasn't arrived yet (it should be here tomorrow according to USPS tracking). 

Last night, I took that long cable out and swapped in the 1M Raven Audio Soniquil RCA interconnect cable I was using for my Cassette deck. The sound INSTANTLY improved. A LOT. The invisible wool blanket over my speakers is gone. 

I'm still interested in rolling the tubes at some point, but the urgency is gone. I think I'm going to start with switching the input tube to a Raytheon/RCA 5751 with windmill getter or the GE 5751 triple mica. When I finally pull the trigger, I'll update this thread with the results, but for now, I think the problem has been resolved.

Thanks again for all the help

P.S. kudos for identifying the correct issue early in this thread... you had the right idea all along!!

cey's avatar
cey
302 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. 

lradder
57 posts
 

RCA Clear Tops.

Buy from Andy at Vintage Tube Service 

leemark
21 posts
 

The Quicksilver preamp tubes are curve traced at all frequencies. You will likely not do better than stock. Try a golden dragon in place of the JJ 12at7 however I have two of these units with stock tubes and they are the opposite of warm wet blanket. Check the input impedance of your one preamp. That can definitely give you a dark thick sound. Check with Mike on the speaks of your line stage. You can also change the input loading resistor to 1 k but that should not be necessary.

tomic601's avatar
tomic601
13,182 posts
 

it also remains to be heard IF your R2R can also drive that 17’ cable…

We all learn

 

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