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I'm new to tubes and appreciate your patience with a newbie.
I just got a Cary Audio SLP - 05, slightly used. It sounds great, but of course I want to see if there's even more to to get out of this great component. It comes with 8 Electro-Harmonix 6SN7 tubes for the balanced, headphone and gain stages and 1 5AR4 rectifier tube in the power supply
I've seen an old thread from 2011 on this here at Audio Asylum. On www.thetubestore.com there are two upgrade packages for this preamp: 1) Tung-Sol 6SN7GTB and Tung-Sol 5AR4; or 2) EH 6SN7 Golds and Mullard GZ34 / 5AR4. For a lot more $ they also have Northern Electric 6SN7.
I'd like to go with something that will give me a definite improvement without a lot of trial and error (is that possible?).
Any advice you have is greatly appreciated. I'm tempted to go with the Northern Electric 6SN7 and the Mullard 5AR4.......
Follow Ups:
I installed a sextet of these about 3 months ago in my SLP-05 (don't use the headphone out put so I have an old set of 6SN7's in those positions). Everything about this tube has been excellent: superb tonality across the board, very good dynamics and very quiet/non-microphonic. You can get them for about $45 each. Highly recommended for the Cary SLP-05.
First, tubes 3 and 6 are only used if you are using balanced inputs. If you are using single ended, you do not have to worry about their quality. Supposedly, you can even take them out. And, 7 and 8 only matter for headphones. You may be dealing with only changing 4 tubes. I have EH 6SN7 and am happy with them, but have not tried others.
I just had a blown fuse in my SLP-05 and figured it was the 1970 era RCA 5AR4 going bad so I replaced it with a new Mullard. The difference was stunning. The old tube was clearly passed its peak. The Mullard increased the bass, gave more detail and pretty much improved everything. Honestly, I think it sounds better than with the RCA in its prime. I must admit, I was surprised how much a warn out 5AR4 degraded the sound. The moral is - don't forget the rectifier tube.
Also came across cryo treated tubes and gold pated pins.
Are these worth the cost or just snake oil?
Add some SR diodes to the VR, as Eli Duttman suggests, even add a choke or two and up the filter capacitance a lot. Where possible use film caps in the PSU. And, improve the heater supply as well.A far bigger and lasting improvement.
Warmest
Tim Bailey
Skeptical Measurer & Audio Scrounger
Edits: 07/07/15
This is pretty new to me -- I'm comfortable switching out tubes but if it involves soldering etc I'd hate to screw up a nice piece of equipment (without any experience doing the work). Is it likely Cary wouldn't have done a pretty good job with the power supply? If it would really improve performance and does require tools/expertise I don't have, any recommendations for where to go?
Circuit Design Class A Triode Vacuum Tube Preamplifier Design
................................................................................................................................................
Output Voltage 2 Volts rated, 12 Volts maximum
................................................................................................................................................
Overall Gain 17dB Single-Ended RCA
24dB Balanced Operation
................................................................................................................................................
Rated Distortion 0.03 % THD
................................................................................................................................................
Noise and Hum -90 dB below full output
................................................................................................................................................
Input Impedance 50,000 Ohms - RCA
100,000 Ohms - XLR
................................................................................................................................................
Output Impedance 400 Ohms
................................................................................................................................................
Frequency Response 5 Hz to 250,000 Hz
................................................................................................................................................
Vacuum Tubes 8 ea - 6SN7 tubes for the balanced, headphone and gain stages
1 ea - 5AR4 Rectifier Tube in Power Supply
................................................................................................................................................
Power Transformers R Core 200% Duty Cycle
................................................................................................................................................
Resistors 1% Metal Film
................................................................................................................................................
Capacitors Polystyrene, Film and Foil
................................................................................................................................................
Power Supply Capacitors 2 ea - 560 μF @ 400 VDC
Since you just got the preamp you really should let its "sonic signature" grow on you a bit. If you get the most expensive tube line up that some store is selling how much of a baseline will you have established with just 2 types. IMO, do some trolling and get a good deal on some NOS 6sn7 and then swing for the fences after you have batted around some of those different brands. Happy listening, Dak
Again, thanks for the help.
Some follow up questions:
1) Do the tubes in a preamp need to be matched or is that really just an issue for amps?
2) If they do need to be matched could it be in pairs? a) Right negative and positive gain paired and Left negative and positive gain paired vs. b) Negative right and left paired and Positive right and left paired? Sorry for my utter ignorance here.
3) Could I use different tubes in pairs or quads according to the attached layout or should they all be the same make?
1. 6SN7 tube - left channel positive phase gain - buffer
2. 6SN7 tube - right channel positive phase gain - buffer
3. 6SN7 tube - left channel balanced input buffer
4. 6SN7 tube - left channel negative phase gain - buffer
5. 6SN7 tube - right channel negative phase gain - buffer
6. 6SN7 tube - right channel balanced input buffer
7. 6SN7 tube - right channel headphone amplifier
8. 6SN7 tube - left channel headphone amplifier
They don't all have to be the same or matched. I would use matched pairs for the gain and input tubes. Just a guess, but I would think the input tubes would make the biggest difference. Can't comment on the new reissue recomendations made by others as the only one I have tried is the EH that came with my amp. They are not good IMO, pretty much anything will be better.
There is a lot of info on 6sn7 on this site. You don't have to spend a fortune, Most 6sn7gtbs like Sylvania's or RCA's or GEs are priced similar to new production. 6sn7GT from the 1950s are costlier but sound better generally.
You have a great preamp you should definitely upgrade the EH tubes.
Enjoy the roll!
Thanks for the advice. Reached out to J McShane, looking for the Sylvania and Tung-sol.
Wondering how important matching is for preamp tubes. Or just matching pairs like the left or right channel positive and negative gain buffers.
Whether or not matched tubes are needed depends on the circuitry. Let Jim McShane check for you and heed his advice. Jim is straight shooter! No flim/flam from that quarter.
Eli D.
New Sensor's recent entries in the 5AR4 sweepstakes have been received favorably. However, a pretty simple tweak makes the inexpensive Sovtek 5AR4 rock solid. I've uploaded the graphic (not original with me) for the tweak. Given my somewhat "anal" nature, I suggest UF4007s instead of the 1N4007s, simply because they are quieter. The vacuum rectifier blocks SS diode switching noise from reaching the PSU filter, but (IMO) less noise, from the outset, has to be better.
I strongly 2nd the "reissue" TungSol 6SN7 suggestion. If you want to try NOS, without surrendering body parts, build or buy Loctal/Octal adapters and install 7N7s. External labeling and packaging means nothing, when dealing with Loctal tubes, as all were made by Sylvania in PA. If you do some research, you'll find lots of folks "drooling" over NOS Sylvania made 6SN7s. The "guts" in Sylvania 6SN7s and 7N7s made in the same time frame are the same. ;> )
Eli D.
To the OP . I am a compulsive tube roller let me be clear at the start, I found t interesting and fun substituting various brands and types of tubes and there are a lot of 6SN7s to choose from.
The most actively sought after NOS tubes are the early versions of 6SN7s which are denoted by the GT suffix for the most part. Those get expensive and aren't always in good shape. If you are willing to use the NOS tubes more recently made from the big manufacturers, you will find 6SN7 GTB suffix. There are true electrical differences between them in abundance and in better condition. Generally speaking they are perfectly suitable for most current applications, and are denoted bythe GTB suffix. The current production Tung Sol is a GTB I believe.
The other more recently produced tubes had "coin" bases that are about as thick as a poker chip, I would avoid them.
All that said Eli knows this field and I would take his suggestions seriously.
Steve
good. They won't break the bank either. I have more NOS than I can shake a stick at but I am glad the Tung-sols are around because they really are very good.
5AR4's are wide open. I like and use NOS Mullards, often in metal base but others are good as well.
iBasso DX100,DX50 DX90. Chord Hugo. HiFiman 901 balanced. RSA Intruder, The Lightning. Fostex TH900 balanced, Hifiman HE-6, 560, 500, JH13 Pro balanced. Lyr2, Audeze. All phones balanced mostly with Whiplash cables. Photo gallery: www.pbase.com/jamato8
Contact Jim McShane. At least he can give you the pros and cons of what tubes should work best for -you-.
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