6SN7 via the Garage adapter make Mainline sound better

ipetruk · 2021

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Offline ipetruk

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  • Igor Petruk
on: January 20, 2022, 12:34:53 AM
Hi,

I often roll 6SN7 on my Crack via the Garage adapter. One of the tube I did not like in particular is Psvane Globe. It is pretty brigh, shouty and thin, so I put it in the box.

That tube has an amazing look to it, so I wondered if I can put it in the Mainline for looks alone, since rolling a power regulard should not make a difference.

Oh boy there was a difference. Now Mainline with my Verite Closed sound ABSOLUTELY perfect. There is nothing to add or to remove, pure magic.

When I roll 6SN7 I normally have to put my volume twice as high, they seem to deliver lower gain, at least via that adapter. So it is NOT exactly the same as 12AU7, I don't know in which way exactly. In fact, Psvane in partiular provides THE LOWEST gain even among 6SN7 and it sounds on Mainline the best comparing even to other 6SN7 I have.

I have two questions:

1) Is it safe for prolonged use? If I am not stressing the circuits to it's limit I'd prefer to keep using it as my power regulator. "It works and sounds good" does not mean I am not stressing the Mainline circuits.

2) What could be the reason for a better sound? Rolling 12AU7 should not make the difference, but 6SN7 is slightly different.

Thank you.

Roon -> Raspberry 4 -> Khadas Tone in Bottlehead Crack+Speedball -> detachable cable modded DT880


Offline Paul Birkeland

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Reply #1 on: January 20, 2022, 05:41:18 AM
The 6SN7 is going to draw some extra heater current and will heat up the 1085 regulator a bit more.

The 6SN7 would otherwise operate electrically just fine. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline ipetruk

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Reply #2 on: January 20, 2022, 05:50:33 AM
I wonder if better sound comes from heating up that regulator? Maybe it works better at higher temperature.

Everything sounds much crisper, it's almost like a Speedball on Crack. Maybe to a less degree, but it definitely goes towards clarity and separation

Roon -> Raspberry 4 -> Khadas Tone in Bottlehead Crack+Speedball -> detachable cable modded DT880


Offline Paul Birkeland

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Reply #3 on: January 20, 2022, 05:55:38 AM
The regulator and tube heaters in general are not in the signal path, provided that the heater voltage is adequate and not limiting emission.

The tube specs are pretty similar between the 12AU7 and 6SN7, especially in regulator duty, so it's tough to say what accounts for the differences you're hearing. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Doc B.

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Reply #4 on: January 20, 2022, 07:45:39 AM
It's really hard to say what is causing the difference without hearing it. Have you tried different 12AU7s and heard a difference? That might help you along the path to figuring out what makes the difference. I would not say that swapping tubes make no difference. Just that, IME, the differences are pretty small. And that, as you found, what makes for a good audio tube might be different than what makes for a good regulator tube.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline Tom-s

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Reply #5 on: January 20, 2022, 10:32:58 AM
When I roll 6SN7 I normally have to put my volume twice as high, they seem to deliver lower gain, at least via that adapter. So it is NOT exactly the same as 12AU7, I don't know in which way exactly. In fact, Psvane in partiular provides THE LOWEST gain even among 6SN7 and it sounds on Mainline the best comparing even to other 6SN7 I have.

Could a more knowledgable soul than myself help me out.
Why does a regulator tube have any influence on perceived volume / loudness?

Espescially on an amp like the Mainline. Where there's a CCS after the shunt regulator tube.



Offline Paul Birkeland

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Reply #6 on: January 20, 2022, 10:35:39 AM
Why does a regulator tube have any influence on perceived volume / loudness?
It should not.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline ipetruk

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Reply #7 on: January 21, 2022, 01:31:53 AM
Rolling 12AU7 makes some difference, with more like 90% of tubes being the same, and 10% sounding worse.

Putting 6SN7 was a surprise. And again, 90% of 6SN7 were the same, but this stood out. As I said, it also stands out in Crack, where my normal listening volume is usually 30%, but for this tube it has to be noon.

I don't really know what is the role of the regularor tube, since there is already a solid state regulator there. You often explain that it "helps", but it is not quite clear I guess without understanding the circuit how specifically. Maybe having lower gain there makes that impact.

Roon -> Raspberry 4 -> Khadas Tone in Bottlehead Crack+Speedball -> detachable cable modded DT880


Offline Doc B.

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Reply #8 on: January 21, 2022, 06:19:25 AM
Measure voltages before and after you change to the 6SN7. Collecting data is the logical thing to do if you are trying to understand what might create the difference.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.