BTW, I'm looking forward to one of Thomas Mayer's great tube deconstruction photo sequences of this tube.
In the past Thomas never wanted to use this tube - I don't know if he's changed since then!
Indeed. I'm going after my third incarnation of the "Siberian" preamp. I will run the 4P1L rather hot at 35mA with an LL1660 in 4.5:1 to provide low output impedance and drive to my system.
Just started filament supply - choke input
Siberian DHT Preamp Gen3: filament supply | Bartola Valves
cheers
Ale
Just started filament supply - choke input
Siberian DHT Preamp Gen3: filament supply | Bartola Valves
cheers
Ale
I hope not!Spent emission
In pic three and four I cleaned the glass with some toothpaste.
Attachments
Indeed. I'm going after my third incarnation of the "Siberian" preamp. I will run the 4P1L rather hot at 35mA with an LL1660 in 4.5:1 to provide low output impedance and drive to my system.
Just started filament supply - choke input
Siberian DHT Preamp Gen3: filament supply | Bartola Valves
cheers
Ale
Hi Ale,
In my last built PSE I tried it at 40 mA and was the best sound right there.
My OPs were 70 mA so I had to let them run at 35mA, 250V.
I am curious to find out how long they will last running them at 10W.
I have to figure out how to run a accelated test at 40 mA. I dont want to spend 6 months to figure this out.
Best,
Radu
Talk of questionable 4P1Ls reminded me that I bought some a while back but I've never used them. I've just had a quick look at them and wonder if some might be a bit dodgy. They were sold as NOS but at least half of them look a little "milky", perhaps like Bas', though it looks to be internal. In the attached photos the valve which looks good is on the left and the dodgy one on the right. Might they be less than perfect?
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I'm convinced mine are new. They look almost identical too the ones posted on Siberian shop's versions. Why would they post ones with visibly spent emmision. The base and pins also don't look tarnished whatsoever...as is the case in one of Kevin's 4p1l's.
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Last edited:
Sockets FOR Tube 4P1L 4P1? RL2 4P6 Wermacht X 2pcs | eBay
This could offer opportunities to add sound-dampening material to the cylinder of the socket.
This could offer opportunities to add sound-dampening material to the cylinder of the socket.
Did not see anything there
Are these bottom mount phenolic mounts?
I found some made by EDISWAN that seem like they could be good.
Reminds of when Harry Pearson's favorite 12AX7 was made by EDISWAN.
I like the idea of phenolic better than ceramic.
Ordered some 4P1Ls today along with the COLEMAN filament regulators.
Sockets FOR Tube 4P1L 4P1? RL2 4P6 Wermacht X 2pcs | eBay
This could offer opportunities to add sound-dampening material to the cylinder of the socket.
Are these bottom mount phenolic mounts?
I found some made by EDISWAN that seem like they could be good.
Reminds of when Harry Pearson's favorite 12AX7 was made by EDISWAN.
I like the idea of phenolic better than ceramic.
Ordered some 4P1Ls today along with the COLEMAN filament regulators.
A new improved loctal socket board to reduce microphonic noise in the preamp. Using silicone rubber layer between PCBs and silentblock. Looking forward to implement it soon:
Looks a bit like what I used on my 26 preamp. Works great...
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