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A question for 45 SET experienced listeners

Hello,

A few months ago I posted a topic regarding speakers paired with a 45 SET amp. Well, I am still debating the purchase of one since I adore my 2a3 to no end. I own a Triode Lab 2a3 and a Triode Lab/Finale 300b. I enjoy both for different reasons, as I'm sure you guessed. My 2a3 uses a 6SN7 drive tube and the 300 a 12AX7. Well, the amps Frank creates are just treasures to me, but I only just came to the conclusion that I would like a 6SN7 tube to drive my 45. Well, I took a look at the Triode site and bam, I see a 12AX7 on Frank's 45 amp. I will talk to him about it, but I was hoping to get some advice from some of you regarding your thoughts on the 6SN7 and 12AX7 driving a 45 tube.

Basically, do you guys think a 6SN7 in a 45 amp would perhaps render a bit too much bloom? I enjoy the sound of mellow, thicker, warmer amps, but must admit I am curious if this may be too much, and maybe the 12AX7 would be the right choice.

I was a classical musician and enjoyed warmer instruments. Classical is the primary music genre I listen too, so Heifetz through a mellow sounding system is just right for me. Though, not a 'honey' viscous thick system.  

What do you guys think? Ideas?

And if this may help any, I am using Omega speakers. They have plenty of air on top, with the soundstage up there just as plentiful. So, this is only a guess, but I'm thinking even more warmth, beyond that of my current amps, may be a good thing. 

Thanks for reading,
robert
vvcv
6 responses Add your response
larryi
4,033 posts
 
I am a fan of both 45 and 2a3 tube myself.  I own a parallel SET 2a3 amp and a pushpull 45 amp.  I have heard numerous 45, 2a3 and 300b SET and pushpull amps.  As a general observation, the 45 is like the baby bear in the "Three Bears" children's story in that it sits sonically between the 2a3 and 300b--it is not as lean sounding as the 2a3, but it does not have as much of the upper bass bump up and warmth of the 300b.  I like the 300b warmth and midrange beauty, but, that tube lacks the liveliness of the 2a3 and 45.  Overall, I like the tonal balance of the 45, the tight but not thin bass of the 45 over the somewhat lean character of the 2a3.  I loaned the parallel 2a3 amp to a friend and I have given him permission to convert it to a parallel 45 amp. 

I don't know about what driver tube is best with the 45.  I know a builder who prefers the 6sn7 for all three of these triodes because it has a bit more oomph than the 12ax7 family of tubes.  I think there is a wide enough range in sound of 6sn7 tubes for you to find one to match your preference.
alexberger
916 posts
 
I don’t understand why some digners use 12AX7 to drive any ouput tube in SET amplifier. I also don’t think that 6SN7 is a good driver for 300b.
In my 300b amp 6F6g in triod mode is used as driver.
And it doesn't sound slow at all.
Coincidence Frankenstein 300B amplifier has even more powerful driver than 6F6 and sounds very dynamic and fast.
I read one Russian DIYes forum. One guy tried dozen different driver tubes in 300B amplifier including 2A3, 45, 6F6 and he told the best driver for 300B was 300B, and the legendary Japanese designer Sakuma used 300B driver in his 300B amplifiers. 
I think to use 6sn7 driver for big tubes like 300B, 845, 211 it is similar to using 1 liter engine in track.
atmasphere's avatar
atmasphere
11,841 posts
 
I've used a 6SN7 in a type 47 SET and it worked fine. Not too rich at all!
alexberger
916 posts
 
Hi @atmasphere ,

Do you know why so many designers use 6sn7 driver for 300B and even 211 and 845 tubes?
1. Do they want to achieve a special slow signature of an amplifier sound?
2. Do they do it as result of lack of knowledge and experience?

Regards,
Alex. 
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atmasphere's avatar
atmasphere
11,841 posts
 
Do you know why so many designers use 6sn7 driver for 300B and even 211 and 845 tubes?
1. Do they want to achieve a special slow signature of an amplifier sound?
2. Do they do it as result of lack of knowledge and experience?
@alexberger

To the first, no. I've yet to ask any designers of amps using those tubes why they made any of the choices they did.

To the second, no. You have a different set of issues with the tubes you mentioned- getting bandwidth in an SET of the power levels these tubes are capable of is increasingly more difficult for the output transformer as the power level is increased. I could see that lack of bandwidth being construed as 'slow'.

To the third, no.


You can get good bandwidth with a 6SN7 and you can get low distortion owing to good linearity. So it can be quite neutral, and has the advantage of being capable of fairly high current, so you can drive a fairly high capacitance grid with it no worries. The grids of the power tubes you mentioned would be a walk in the park for this tube. Since its designed for audio, its easier to find lower microphonic examples than it is to do so for something like a 6922 or other frame-grid triodes. A further advantage is that its in production and easy to get. Its also pretty reliable.
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