Croft preamp - 12BH7A or 6SL7?

[Firebottle]

Just a couple of resistor values I would have though Nick, it is just a line stage with the gain set by feedback.

[lurcher]

Yep, but the difference in gain of the two, 60 and 10, is going to mean a lot more feedback with the 6sl7. so I would have thought the spectral output of the two would be very different. Also I assume there is a cathode or source follower on the end, there have been in the ones I have seen. Otherwise the different ra will make a difference to its load driving ability. All the Croft stages I have seen have been anode followers plus a source follower inside the feedback loop. Are there different sorts from that? The difference between the two valve would make me think you could use any dual triode with relevant anode load and feedback resistor.

I would have thought a 6072a would make a better 9pin version of the 6sl7. Or a 6sn7 as an octal replacement for the 12bh7

[mathewf]

Yep, but the difference in gain of the two, 60 and 10, is going to mean a lot more feedback with the 6sl7. so I would have thought the spectral output of the two would be very different. Also I assume there is a cathode or source follower on the end, there have been in the ones I have seen. Otherwise the different ra will make a difference to its load driving ability. All the Croft stages I have seen have been anode followers plus a source follower inside the feedback loop. Are there different sorts from that? The difference between the two valve would make me think you could use any dual triode with relevant anode load and feedback resistor.

I would have thought a 6072a would make a better 9pin version of the 6sl7. Or a 6sn7 as an octal replacement for the 12bh7

From what I understand the circuit is quite different for the Octal and 12BH7.

[mathewf]

Seems there is a 6SN7 option as well as the 6SL7 for the 25RS LS

The 6SN7 is more neutral from what I understand so possibly the way to go - does anyone have any experience either way with 6SN7 vs 6SL7 Croft equipment?

[vinyl]

Have you enquired / put your questions to Glenn?

[mathewf]

Have you enquired / put your questions to Glenn?

I have indeed, he says he has no personal preference...

[vinyl]

My experience with octals - I have a Charisma X pre with phono - it utilises 5 x 6SL7 in total. The phono output stage 6SL7 can be swapped with a 6SN7 to my preference (which I haven't tried). As it uses the two 6SL7 in the line stage, I can easily say it is the most sonically satisfying of any preamp I have heard - and I have heard many including high end / very expensive / call them what you will preamps in comparison with some nudging £10k. That's not to say the more expensive gear isn't good - it is very good but personally not for me.

Glenn has told me Jo's, Marco's and mine are practically the same preamp circuit wise.

Glenn is quite right as the preference in sonics between the two octals will be how you enjoy them and you won't know until you've tried. Glenn welcomes feedback and whatever you choose and then don't enjoy he'll change for you. Hope this helps.

[mathewf]

Glenn is quite right as the preference in sonics between the two octals will be how you enjoy them and you won't know until you've tried. Glenn welcomes feedback and whatever you choose and then don't enjoy he'll change for you. Hope this helps.

Thanks vinyl, yes it does. I'm pushing ahead with the 6SN7 version (if only because no one else seems to have), I'll see how I get on.

[The Black Adder]

Seems there is a 6SN7 option as well as the 6SL7 for the 25RS LS

The 6SN7 is more neutral from what I understand so possibly the way to go - does anyone have any experience either way with 6SN7 vs 6SL7 Croft equipment?

Hello Mathew.

I have the 6SN7 version and it's really very nice indeed. Mine now runs 2x 6LN7's in the line, 1x 6SN7 as the middle and x2 6SL7s in the phono. Let me know if you need to know any other information.

[Jimbo]

Thanks vinyl, yes it does. I'm pushing ahead with the 6SN7 version (if only because no one else seems to have), I'll see how I get on.

I will be keeping an eye on this Mat as I would like a phono stage with 6SN7,s.