12SN7 vs 6SN7

strider

From my understanding of the tube data sheet I found, the only difference on paper between the 12SN7 and 6SN7 tubes is the heater voltage. From a practical standpoint, the 6SN7 are much more expensive, which led to my query.

What are the subjective differences between the two tubes when used as the input and output tubes of a preamp? They'd be going in my Aikido Octal preamp, which has the capability to be set up for either tube type.

Any 12SN7 to look for specifically?

schwarcw

Ben, get some Sylvania 6SN7. Good used ones are about $100/quad. 6SN7s are some of the cheapest and most musical tubes out there. Many were used as tone tubes for organs. They are readily available and many varieties to tube roll.

Face

I agree with Carl.

strider

I hear you, guys, and actually have some of the newer Sylvania 6SN7 in there now. Also have some RCA 6SN7 that are close in build date, but not tested or matched.

Here's what I'm seeing, though. The equivalent 12SN7 tubes are at least half as expensive. Matched pair 1950's RCA 12SN7 for $19.00, Sylvania chrome domes for $15.00, and that's just a quick Ebay search. Just looking for a cheaper way to skin a cat.

heiney9

schwarcw wrote: »

Ben, get some Sylvania 6SN7. Good used ones are about $100/quad. 6SN7s are some of the cheapest and most musical tubes out there. Many were used as tone tubes for organs. They are readily available and many varieties to tube roll.

Face wrote: »

I agree with Carl.

I agree with both. A favorite is the 50's "Chrome Dome", black plate w/square getter. I use the the 6SL7's in a piece of gear and the Sylvania's are my favorite, very similar to the 6SN7. Even the 60's gray plate round getter sound great!

Many times when you run tubes out of spec 6V vs. 12V they don't sound as intended because you are out of the optimal operating range. Plus a 12v tube will draw twice as much as 6v tube, is your piece of gear up for that? I'd be sure and do a lot of research before subbing those.

H9

strider

heiney9 wrote: »

Many times when you run tubes out of spec 6V vs. 12V they don't sound as intended because you are out of the optimal operating range. Plus a 12v tube will draw twice as much as 6v tube, is your piece of gear up for that? I'd be sure and do a lot of research before subbing those.

H9

The pre is designed to run a pair of octals in the input and a pair in the output. The 6SN7/12SN7 produce a gain of 10 when used in all positions, IIRC. If I'm interpreting the manual correctly, the only difference in the circuit would be the need for a 12.6v signal to the heaters on the 12SN7 vs 6.3v for the 6SN7. The tube data sheets for the 6SN7 and 12SN7 are on the same document, with the 12SN7 needing twice the voltage but half the current for the heater grid.

mhardy6647

6SN7, 12SN7, 7N7 (Loktal base, 6.3 V filament) are all the same in terms of performance; try 'em all! In fact, the 76 is half of a 6SN7. There's gold in them thar hills.

http://www.nutshellhifi.com/triode4.html

ALL212

heiney9 wrote: »

I agree with both. A favorite is the 50's "Chrome Dome", black plate w/square getter. I use the the 6SL7's in a piece of gear and the Sylvania's are my favorite, very similar to the 6SN7. Even the 60's gray plate round getter sound great!

Many times when you run tubes out of spec 6V vs. 12V they don't sound as intended because you are out of the optimal operating range. Plus a 12v tube will draw twice as much as 6v tube, is your piece of gear up for that? I'd be sure and do a lot of research before subbing those.

H9

12V tubes do not necessarily "draw" twice as much as a 6v tube. What exactly are you refering to drawing? I suspect watts (or volts or amps or...)? But in this case the 12 gives 0.3 Amps of heater current at 12.6 volt and the 6 gives 0.6 Amps at 6.3 volts, so 37.8 Watts of heater power either way.

The OP also states his amp can be set up either way so his gear obviously is up to that. He would just need to make whatever adjustments his amp requires and plug 'em in - no research required.

Find a good set of either and have fun!

strider

mhardy6647 wrote: »

6SN7, 12SN7, 7N7 (Loktal base, 6.3 V filament) are all the same in terms of performance; try 'em all! In fact, the 76 is half of a 6SN7. There's gold in them thar hills.

http://www.nutshellhifi.com/triode4.html

That's what I'm digging for, the gold! Anyone can go to a jewelry store or what not and pay through the nose, but it's really good when you can find it yourself...

ALL212

ACK!!! Who moved my decimal?! 3.78 watts of heater power not 37.8 watts - that might be a bit interesting.

:redface:

strider

Here's a link to give a better idea of what the tubes are going in. Just re-read the post and realized that wasn't very clear. Built mine a while ago, had it set up with a 6.3v power supply for the heater circuit which dictates (for the most part) the use of a 6.3v tube in the input and output. With a couple of jumper wire changes and a 12v transformer I found in my parts bin, I'll soon be set up for running the 12SN7 I bought.

Ended up with a "platinum" low noise pair of 1957 Sylvania 12SN7GT chrome tops and a pair of NOS GE 12SN7GT from the early 60's to start. Grand total of $52, shipping included. Not too bad, compared to the price of comparable 6SN7.

JerryS

Plenty of disinformation here. There is zero sonic difference between a 12sn7 and a 6SN7. The only diff is the heater voltage. The heaters were originally powered by batteries of the lead-acid variety and that is why you see the "weird" voltages, 6.3 instead of 6 even, 12.6 instead of 12 even. There is a very good sound quality reason to go with 12 volt heaters, which I do whenever possible: Power supply hum. The 12 volts AC is readily rectified into 12 volts DC. The 12 volt heaters will draw HALF the current of the 6 volt version. Power equal volts times amps. Instead of speculating, LOOK UP the data sheets. They will show half the current draw for 12-volt tubes versus 6 volt. The 0.7 volts dropped across the diodes isn't noticed with 12 volts, more noticeable with 6 volts. Also, the diodes only need to be able to pass HALF the current if you are using 12 volts. Save yourself some money. Use 12 volt tubes. Even if I have to use 6 volt power tubes, I simply wire the heaters in series to make a 12 volt heater circuit work.

Here's what I'm seeing, though. The equivalent 12SN7 tubes are at least half as expensive. Matched pair 1950's RCA 12SN7 for $19.00, Sylvania chrome domes for $15.00, and that's just a quick Ebay search. Just looking for a cheaper way to skin a cat.[/QUOTE]

tonyb

Actually a few reviewers have noted better low bass response with the 12's. Mapletree is another bang for your buck pre that uses both tubes.