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i would agree with the comments so far regarding higher voltage 'replacements' for the 6SN7s. i would like to add 2 more advantages of using higher filament voltages:
- less hum; a higher voltage means less current. current generates magnetic fields. magnetic coupling means hum. hence less current = less hum.
- you can get cheaper filament trannies for 12V.
fwiw, iirc there are also 25n7s and 40n7s out there.
Well - I have this BRIMAR 13D1...also a 25V filament. The thing is that I only have one: I’ll need two more, and a different heater wall-wart, for my 6V/12V MPX3. On the other hand, I do very little tube rolling nowadays. If anyone would like to have it, give me an offer.
EDIT: A 13D1 is supposedly a 25V filament 6SN7...
__________________ A truth only last till something else is more true. /Glod
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In an eBay search for 6SN7 variants, I came across this auction. The tube appears to be a RCA 5692 manufactured by Marconi-Radiotron, a company that in this thread does not seem to be credited with making a 5692. I'm certainly no expert on tubes, but I thought I would post this so those who are more knowledgeable could look into it.
I use these tubes in an integrated amp and not for a headphone amp, but still wanted to share my 2 cents.
As noted, combining tubes will often produce the best results. My amp uses 4 6SN7's per channel and I have settled (repeatedly) on the following combination:
Sylvania 6SN7W tall bottle
Tung Sol RP
B65 Marconi/Osram/GEC (All sound the same for vintage UK manufactured. Foreign made B65's are not in the same league)
Swedish Standard 33S30
The Sylvanias and TS's have been well covered here and I agree with the general consensus.
The B65 has gone largely undiscussed. In the combination that I use, this tube adds depth to the soundstage and places instruments accurately. It also smoothes out highs, such as triangles, that can be shrill when using only the Tung Sol, for instance. When used alone, it has strong bass, but is slower than the Sylvania or TS. It is also a touch euphonic (though it does not roll off the high end). For me, this actually complements the other tubes well.
I find the Swedish Standard to be a stellar tube. Adhoc and Len have mentioned that it is a 5692 in construction. However, it sounds nothing like an RCA or CBS.
I must note that I do not have 8 of the Swedish standards and, therefore, cannot describe them as a stand-alone tube. I have tried the Sylvanias, Tung Sols, and B65's alone and have found it best to use a pair of each rather than 8 of a single make.
Anyway, the Swedish Standard, when used with the other tubes, provides unsurpassed neutrality. It seems to allow the other tubes to shine in their particular areas of strength while mitigating their flaws. Instruments and vocals are anchored, bass tightens, soundstage opens, clarity increases, timbre becomes more natural, and timing is made more accurate.
Would I use the Swedish Standard if I only had a single 6SN7? I have no idea since I can't attribute its benefits to the tube itself without hoarding a bunch more and slipping them into all 6SN7 sockets, but I would certainly give it a try if you use multiple 6SN7's.
I hope that this was helpful for the 33S30 and B65's that haven't been covered much in this thread.
"I hope that this was helpful for the 33S30 and B65's that haven't been covered much in this thread."
Are these two tubes "drop-in replacements" for the 6sn7? What kind of prices do they go for.
- augustwest
I would consider the B65 a direct drop in for a 6SN7GT. (edited)
The B65 has what many consider to be 'tipped up' highs that add an unnatural amount of 'shimmer' to music. Also, IME they are extremely prone to microphonics. Perhaps a lot of the mystique has to do with the metal bases earlier examples of this tube come with?
I have tried the Osram (2) and Marconi (1) flavours and did not like them - that's not saying others cannot though. They come up from time to time on eBay and I would expect them to go for ~$50 minimum each in fair condition (ie not testing as new).
The 33S30 is AFAIK identical to a 5692, so use it as you would a 5692.
It is also exceedingly rare - I have only come across 2 examples in the last 3 years on eBay. In one instance, it was labeled correctly (Swedish Standard) and went for an astronomical price; in the other it was labeled 'Haltron 5692' and went for a pittance.
The trick is to look closely at the plates - do they have a 'dirty black' (as opposed to flat black or matte black or shiny black) coating and numbers scratched on? If so, you're good to go. When labeled correctly, these tubes can go for upwards of $150 per tube.
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The one constant in life is change, so will that change?
Feel with your own heart, see with your own eyes and hear with your own ears. Sand is sand no matter where it is found. Listening to: The Greatful Dead, The Closing of Winterland 1978, Fillmore West 1969, Lucinda Williams Favorite headphone: Ultrasone Ed. 9 #1010 Listening to: Predator- an exceptional portable, Woo 6 Modified-pseudo dual PS, iBasso D2 Boa, the new Xin Reference Portable amp ratings: *1. a. Xin Reference 12,000uf, b. RSA Predator*2. iBasso P2 *2. Micro IV*3. Mini IV *3. SR71 *4. D1 iBasso upgraded amp *5. iBasso P1 (upgraded opamps) *6. C & C Box (good decay, tilted up high frequency, slightly synthetic) *8 iBasso T1 *9. iBasso T2*10. XTRA X-1 (warm not neutral, very musical) *11. LD M+ These amps are enjoyable to listen to and present a slightly different interpretation of the musical signal. Portable monitor ratings: *1. PortaPros, KSC35 (modified-a great value) *2. Amadana P-117 bamboo *3. UM2 (respond to top quality amplification but I don't enjoy their sound) *4. OVC 8+ Source: iRiver H130,140, D303 optical out, D-EJ955, D-EJ1000, D-EJ2000, 25s, 25, D-303, D-777 and others (optical out if available) Digital Conversion: Altoid tin Monica Dac I, Altoid tin Monica II Asynchronous Reclocking Dac. Headphone Amplifiers: iBasso D1, IV Micro, IV Mini, Xin Reference, SM3B, SuperMacro V LE, SM3 V6 Xin (IV all switches), XRTA X-1, LD Micro +, LD Micro Tube, C&C Box, iBasso P1, P2, D1, D2, Woo 3 Modified-Siemens 6922 driver, 7236 power tube, Woo 6 Modified Pseudo dual PS - Headphones: Ultra Ed. 9, HD650, Ultrasone 750, HFI780, PortaPro modified, KSC35, Equation RP-21, Westone UM2
What is the average life of a NOS '40s-'50s 6SN7 ?
Any links, resources on the subject ?
Depends on how long you run them.
5692 - 275 Volts maximum & maximum 1.75 Watts per section
6SN7GT/WGT -- 300 Volts maximum & maximum 3.5 Watts per section
6SN7GTA/GTB - 450 Volts maximum & maximum 5.0 Watts per section
Using the general audio application of 250 plate volts, a bias of 8 volts results in 9ma of current and a plate dissipation of 2.25 Watts, we find:
5692 - runs 43 % over maximum rating – It isn’t a 10,000 hour tube when you run it this HOT!
6SN7GT - runs 64% of maximum – coasting and liking it
6SN7GTA/GTB - runs 45% of maximum – Hardly turned on, may outlast you.
"5692 - runs 43 % over maximum rating – It isn’t a 10,000 hour tube when you run it this HOT!
6SN7GT - runs 64% of maximum – coasting and liking it
6SN7GTA/GTB - runs 45% of maximum – Hardly turned on, may outlast you."
Linear Mode
