R52 alternate tubes

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Learning to Wiggle
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R52 alternate tubes

Post by Sookilala » Thu Sep 12, 2019 7:48 pm

Hi All

Proud owner of a bunch of yellow here

I want to buy some alternate tubes for my R52

Have read in the documentation the R52 is wired for all manner of pentodes...
12AU6, 12AW6, 12BA6 being recommended but capable to accept 12BL6, 12CN5, 12CX6, 12CY6, 12DK5, 12DK6, 12DT6, 12EK6, and 12EZ6.

Does anyone have any experience loading the R52 up with tubes other than those supplied??

Reading through the forums I can see examples 12AW6s being described as "more nasty"

Personally I would be after smoother results. I love the R52 but I find the range for me is exceptionally narrow (not narrow in the freq domain but the resonance)

If anyone has tried different tubes, particularly if said tubes tamed the resonance a little?
Sometimes screamy is good but I always find its a very fine line between the effect kicking in and taking off (I realize big differences in fine settings is a part of the metasonix experience)

Love the rich tones of all my yellow

Thankyou all in advance.

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Yes Powder
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Post by Yes Powder » Thu Sep 12, 2019 9:46 pm

12AU6s will tame it somewhat. I had a pair in mine for a while, but ultimately decided that I felt the resonance control had more range with AW6s and switched back to those. YMMV

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Post by luchog » Fri Sep 13, 2019 1:05 am

Moved house last year, and one of the tubes on my R-52 got damaged in the process, so I bought some replacements. Picked up a trio of Mullard 12AW6s for $4 each, and a trio of Telefunken 12AU6s for $9 each. All NOS, not pulls. (Three so I had spares just in case.)

The 12AW6s definitely have the more aggressive sound, steeper cutoff slope and sharper resonance. But I find I like the softer response of the 12AU6s better. "Tamer" is a good description of the sound, it's smoother and easier to control.

The difference isn't enormous, but it's definitely noticeable.

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Post by Sookilala » Wed Sep 25, 2019 6:56 pm

Thanks for the responses I really appreciate it :)

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Post by metasonix » Thu Oct 31, 2019 2:24 pm

PS in case you're wondering: we used AW6s because they had high gain and were dirt cheap and easy to get. They also have much higher signal distortion than AU6s.

I tested pentodes for Vacuum Tube Valley magazine long ago. (LONG ago, like 1994). Should you be insane enough to wish to build a low-distortion audio preamp out of pentodes, these are some of the best. Helps to explain why we see 6J7/12J7s, 6AU6s, EF86s, Western Electric 310As, and 12BY7s in old pro-audio and hifi equipment.
in triode connection:
12J7GT RCA 50s 37k .005 .002 -4.8 .63
6AK6 JAN RCA 1954 12k .007 .015 -1.6 1.25
12BY7A GE 70s 25k .015 .010 -1.0 .44
310A WE 50s* 97k .015 .005 -3.6 .67
3S4 JAN RCA 1957 48k .015 .015 -4.8 2.25
EF86 Valvo 50s* 240k .020 .020 -.67 .34
6AC7W JAN RCA 1953 48k .020 .005 -1.5 .26
7788 Amperex 60s* 193k .022 .012 -1.2 .26
5654/6AK5 Raytheon 50s 97k .025 .010 -1.2 .46
EF86 Telefunken 50s* 240k .025 .020 -.95 .39
6J7GT RCA 50s 48k .025 -1.81 .67
in pentode connection:
3Q4 JAN RCA 1949 97k .010 .030 -11.8 .23 100v on screen
6AK6 JAN RCA 1954 240k .030 .025 -10.9 .63
3S4 JAN RCA 1957 97k .045 .020 -11.5 2.3 100v on screen
310A WE 50s* 97k .045 .065 -6.8 .13
6AG7Y JAN RCA 1957 12k .055 .002 -6.3 .23
12J7GT RCA 50s 240k .060 .002 -8.4 .090
12SJ7 RCA 50s 193k .065 .005 -10.2 .13
6AC7W JAN RCA 1953 193k .070 .005 -4.9 .047
12BY7A GE 1962 25k .070 -5.16 .29
6AU6A GE 60s 292k .085 .002 -5.0 .061
6SG7 JAN GE 1952 193k .100 .005 -11.6 .30
12BY7A Raytheon 60s 25k .115 -4.01 .21
6J7GT RCA 50s 292k .120 .177 -7.49 .39

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Post by Moog$FooL$ » Thu Oct 31, 2019 3:09 pm

IMHO 6J7's & 6SJ7's in some of the old Valco low wattage combo amps i've owned & played are just fantastic. sure they often have microphonic issues but you can usually find a tube that works fine.

Eric, what are those numbers you list above after the tubes in triode & pentode connection??? do you feel like telling us about this testing session??

you need to write a book! :bananaguitar: :sb:
i use to drink & smoke.
that fat cat had to go..... wasn't even mine.

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