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Help choosing a quad of 6SN7 tubes

104.172.19.114
Posted on January 11, 2017 at 14:44:12
scruffy_
Audiophile

Posts: 1665
Location: Los Angeles
Joined: August 5, 2005
 I just purchased a Schiit Freya preamp that's being used with Magnepan speakers and it's on the bright side. Can anybody suggest some tubes that will tame the brightness?

~~~~~~~~~~~~~~~~~~~~~~~~~~~
"Humility is the true mark of genius. Just get used to it."
-Anonymous

 

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How Do You Know It's the Tubes?, posted on January 12, 2017 at 08:37:50
Triode_Kingdom
Audiophile

Posts: 10041
Location: Central Texas
Joined: September 24, 2006
 Whan an amp or preamp doesn't sound right, the first thing I do is measure frequency response and distortion. It's a shot in the dark changing anything until that's done, and measurements are a lot cheaper than a quad of NOS 6SN7s.



 

It's not the tubes!, posted on January 13, 2017 at 10:37:49
scruffy_
Audiophile

Posts: 1665
Location: Los Angeles
Joined: August 5, 2005
 There was a midrange glare, but only on a few CDs that did not create any problem when I had my passive preamp installed, and I mistakenly called it "brightness" which people attribute to higher frequencies. It only occurred on a few female vocals and some piano. I now attribute this glare to poor recordings, but I'm still a little mystified why these CDs did not seem to have any glare with my passive preamp. I did order some used RCA 6SN7GTB getter tubes, but I'm now kicking myself because I now believe that they will probably restrict the extended frequencies and color the midrange.

~~~~~~~~~~~~~~~~~~~~~~~~~~~
"Humility is the true mark of genius. Just get used to it."
-Anonymous

 

RE: It's not the tubes!, posted on January 13, 2017 at 22:29:37
fred76
Audiophile

Posts: 1586
Location: Manila
Joined: February 28, 2004
 Hi,

I think those RCA's would actually sound better IMO. I haven't heard newer Russian SN7's, but the older Sovteks had that sound you described in the mids.. It's usually the operating points that shifts how it sounds too. In fact, it plays a bigger part as well as the overall circuit design. So cheer up, your new RCAs would most probably be still be an upgrade.

I also noticed that Schiit uses Wima MKP caps for coupling in their other tube preamp. I surmise they use the same on your preamp. I find Wima MKPs a bit dry and grainy in the upper mids. The only Wimas I liked are the smaller lower voltage FKP's in digital circuits and some solid state riaa analog eq filters. The (non-boutique) radial caps I liked better are the blue ones made by Epcos and Evox-Rifa. But since Schiit chose Wima, your best recourse is to try better tubes.

 

RE: It's not the tubes!, posted on January 13, 2017 at 12:41:27
sony6060
Audiophile

Posts: 1465
Location: USA
Joined: August 8, 2014
 Well with a change in high frequencies per original post order Sylvania 6SN7GTA, The 'GTA' guarantees 1950-1953 era tubes. These tubes are ultra clear sounding unlike a lot of other 6SN7s and has nice clean treble.

 

is it OK to mix the tubes?, posted on January 13, 2017 at 23:33:43
scruffy_
Audiophile

Posts: 1665
Location: Los Angeles
Joined: August 5, 2005
 I have read several times that the tubes can be mixed for better sound. I tried to coax Schiit into revealing the make of the stock tubes but they would not say!

~~~~~~~~~~~~~~~~~~~~~~~~~~~
"Humility is the true mark of genius. Just get used to it."
-Anonymous

 

RE: RCA 6SN7, posted on January 11, 2017 at 17:44:19
DAK
Audiophile

Posts: 2712
Location: PACIFIC
Joined: August 8, 2010
 If you want to get USA made, which frankly are some of the best for price, IME, RCA seems to be a more laid back type tube. There are NOS available here and there. You would probably need to make a purchase or 2 to get 4. The "black glass" type are usually expensive even used and maybe microphonic. Make sure you know what to look for so you don't get ripped off. Also if your preamp is new there will be some time that it needs to burn in before the sound settles down.

 

RE: Help choosing a quad of 6SN7 tubes, posted on January 11, 2017 at 16:37:06
Chip647
Audiophile

Posts: 2647
Location: The South
Joined: December 24, 2012

They would appear to be Schiit.

 

RE: Help choosing a quad of 6SN7 tubes, posted on January 11, 2017 at 16:58:17
Eli Duttman
Audiophile

Posts: 10455
Location: Monroe Township, NJ
Joined: March 31, 2000
 Agreed. Older Russian and Chinese 6SN7 "equivalents" are guano. OTOH, New Sensor's current production "reissue" TungSol made in Saratov, Russia, is good.


Eli D.

 

RE: Help choosing a quad of 6SN7 tubes, posted on January 11, 2017 at 15:59:18
Tre'
Industry Professional

Posts: 17293
Location: So. Cal.
Joined: February 9, 2002
 What tubes are in it now?

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

They are unmarked. , posted on January 11, 2017 at 16:45:02
scruffy_
Audiophile

Posts: 1665
Location: Los Angeles
Joined: August 5, 2005
 I only have about 30 hours on them, so they may tame by themselves after a few hundred hours. I really like this preamp in that it does not distort my choral music other than making it a little too bright. I'm using an equalizer to tame them now from my computer and I love listening to my music.

~~~~~~~~~~~~~~~~~~~~~~~~~~~
"Humility is the true mark of genius. Just get used to it."
-Anonymous

 

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