CROFT regulation stage valves

[Jimbo]

Anyone noticed much difference replacing the regulation valves in Croft preamps.

I know tube rolling valves in the phono stage makes a large difference but can the regulation stage respond significantly to tube rolling.:scratch:


Any recommendations would be appreciated.:)

[Marco]

Hi Jim,

I presume you're talking about the 85A2/CV449 electric stabiliser valves?

If so, yes, upgrading them to a superior type does make a subtle, but worthwhile, difference. Interestingly, I've just changed the one in my Croft, from a NOS Sylvania to a NOS 1950s Mullard CV449, and noticed a weightier, punchier sound, with a more 'liquid' sounding midrange :)

Therefore, I would be tempted to experiment. I've got a few different ones you could try, if you like, so if you're interested, PM me your addy and I'll pop them in the post :cool:

Marco.

[Jimbo]

Hi Jim,

I presume you're talking about the 85A2/CV449 electric stabiliser valves?

If so, yes, upgrading them to a superior type does make a subtle, but worthwhile, difference. Interestingly, I've just changed the one in my Croft, from a NOS Sylvania to a NOS 1950s Mullard CV449, and noticed a weightier, punchier sound, with a more 'liquid' sounding midrange :)

Therefore, I would be tempted to experiment. I've got a few different ones you could try, if you like, so if you're interested, PM me your addy and I'll pop them in the post :cool:

Marco.

Hi Marco,

I have a nice NOS Mullard in the voltage regulation stage (85A2 electric stabilisation), however it was the other two valves (ECC83's) in the other part of the preamp regulation I was looking at rolling. They have stock JJ Teslas in that position at the moment.

They are the two valves to the right in the middle:)
http://i326.photobucket.com/albums/k424/Spendorsp2/77e9fdeb-badb-49a8-b7bc-57e06c27cfc3_zps11359635.jpg (http://s326.photobucket.com/user/Spendorsp2/media/77e9fdeb-badb-49a8-b7bc-57e06c27cfc3_zps11359635.jpg.html)

[worrasf]

Hi Jim
In my prior 25 and now (Glenn upgraded) 25R I indeed found that different valves in the power stage make a difference. I tried many and various both new issue (TJ Full Music) and NOS (Mazda, Brimar, RCA etc etc) but have fond (for me) NOS Siemens & Halske's give me what I want. The letter" valves resulted in better solution of fine detail and a more "open/airy" presentation - presumably down to lower noise ?

Steve

[The Black Adder]

Yep.. the 85A2 Neons do make a difference as Marco said. I've got a nice pair of Amperex I need to try. The CV449 is the mil spec one. It's all good. :) - Currently run Mullards.

[Jimbo]

The JJ,s can be a bit noisy so might see if I can get some more NOS Tesla,s or some Mullards if I can find them.

Took ages for me to get the NOS Tesla,s which are superb in the phono stage so might take a while to find some nice quiet unused NOS ECC83,s for the regulation stage. :rolleyes:

[Marco]

Hi Marco,

I have a nice NOS Mullard in the voltage regulation stage (85A2 electric stabilisation), however it was the other two valves (ECC83's) in the other part of the preamp regulation I was looking at rolling. They have stock JJ Teslas in that position at the moment.

They are the two valves to the right in the middle:)
http://i326.photobucket.com/albums/k424/Spendorsp2/77e9fdeb-badb-49a8-b7bc-57e06c27cfc3_zps11359635.jpg (http://s326.photobucket.com/user/Spendorsp2/media/77e9fdeb-badb-49a8-b7bc-57e06c27cfc3_zps11359635.jpg.html)

Ah, totally different amp, Jim. Apart from one ECC83 and an 85A2, in the power supply, my amp uses all 6SL7s :)

That single ECC83, however, is extremely influential on sound quality!

Marco.