Crack modified for 6SN7 voltage amplifier
- Thread starter Natural Sound
- Start date
Grainger49
New member
Radio Shack sells small gauge wire. Probably more like 24 AWG or the metric (Chinese) equivalent.
I appreciate the offer, however I touched base with a buddy of mine that hand builds (really sweet) tube guitar amps and told him my plan. He's going to send me something he has lying around that should work pretty slick for a temp solution. Heck, if I hadn't already ordered an adapter I'd probably just make something nice with this and roll w/it.
I got the item pictured above yesterday. Haven't had time to fire up the soldering iron yet though.
My friend also shared the following:
"A few things off the top of my head on the 6sn7...
I really like them, they're an older tube than the noval you're replacing. They pull twice the amount of filament current (600mA) than a 12au7. Make sure your power transformer can handle it. Also, you might notice a 60hz hum if your filaments are AC. Regulated DC on the filaments is the way to go with these tubes, IMO. These tubes can also be quite microphonic. Heat-shink over the tube can help a lot. Have fun!"
My friend also shared the following:
"A few things off the top of my head on the 6sn7...
I really like them, they're an older tube than the noval you're replacing. They pull twice the amount of filament current (600mA) than a 12au7. Make sure your power transformer can handle it. Also, you might notice a 60hz hum if your filaments are AC. Regulated DC on the filaments is the way to go with these tubes, IMO. These tubes can also be quite microphonic. Heat-shink over the tube can help a lot. Have fun!"
Interesting! Your friend's comments would seem to explain some of the posts from users who have reported minor audible hum when using the 9 -> 8pin adapter to run 6sn7's.
Per the crack schematic (in the PDF manual), the heaters on both sockets are drawing AC from the transformer.
Per the crack schematic (in the PDF manual), the heaters on both sockets are drawing AC from the transformer.
In my brief experience, I like the 6SN7 sound. I have two RCA cookie base with the "long legs" and they are microphonic and exhibit some hum, the recent Russian Tungsol is very quiet as is the Sylvainia chrome top. ATM I prefer the Sylvainia. Tube rolling with this amp is a lot of fun if a bit hard on the wallet!!
I got my temporary ghetto adapter wired up and running. The only 6SN7 I have right now is a Tung-Sol 6SN7GTB tall Boy.
It sounds quite nice I think. No discernible hum. I've only been listening for about 15 minutes though. Definitely a different character , more tube-y?
I'm liking it.
Couldn't tell you if I like it better than the NOS Tele smooth plate 12AU7 yet though, going to have to pop that one back in later and do a more direct comparison.
(edit)
I swapped the Tele 12AU7 back in. The the 6SN7 def has a huge bass sound. that's the biggest difference. I still really like this Telefunken though. I can't say yet which I prefer, I like them both.
I might have to try some other 6SN7's yet.....
It sounds quite nice I think. No discernible hum. I've only been listening for about 15 minutes though. Definitely a different character , more tube-y?
I'm liking it.
Couldn't tell you if I like it better than the NOS Tele smooth plate 12AU7 yet though, going to have to pop that one back in later and do a more direct comparison.
(edit)
I swapped the Tele 12AU7 back in. The the 6SN7 def has a huge bass sound. that's the biggest difference. I still really like this Telefunken though. I can't say yet which I prefer, I like them both.
I might have to try some other 6SN7's yet.....
Grainger49
New member
Glad to hear you got there. Multiple brain farts here!
Yup, IME the 6SN7 is always more tubey sounding than a good 12AU7 - one of those cases where they look better on paper, but I find that a good 12AU7 actually sounds more pleasant to me. Haven't tried it myself in Crack, but I will once again recommend a 12BH7 as having that 6SN7 weight without so much of the tubey bits.
Natural Sound
New member
The next step in this journey is to install the constant current boards (speedball). I picked up the kit during the "Black Friday Sale" and they were delivered just before Christmas. My plan is to install the kit in two phases so I can observe the effects on the sound. Phase one will cover the 6SN7 and phase two will be the 6080 tube.
I have one question that I think I have the answer to. I just wanted to ask the guys "in the know" before I warm up the soldering station. Are there any resistor changes on the constant current boards that need to happen for the 6SN7 substitution?
Thanks,
Tom
I have one question that I think I have the answer to. I just wanted to ask the guys "in the know" before I warm up the soldering station. Are there any resistor changes on the constant current boards that need to happen for the 6SN7 substitution?
Thanks,
Tom
Yes!Laudanum said:
PS...My RCA sounds allot like a 12au7 though just average dynamics unlike many of the other 12au7's I have. I think the 6SN7's sound really, really cooool. I just got a russian equivelent in today (Metal base, steel braces, not the cheap plastic crappy version) and it is amazing. The largest soundstage i've heard yet...punchy, detailed, realistic bass, nice high end sizzle. Very Hard to find. I've got my russian inlaws searching for more with very good prospects. I think they bought me a case of them for $30. They sell for $3 ea. over there, Here though Brent Jesse was selling them for $100 and is all sold out! Really worth checking out though e-bay is probably the only source for the moment.
PSS...I probably should move this to the toob rolling thread...but I'll wait for the case to arrive and listen some more.
jrihs ... my post is a bit dated now but appreciate the info anyway. I've been using a 12BH7 in Crack lately. Using FPIII now with 6SN7's and another 6SN7 in Crack is a bit much. I figured after the FPIII with 6SN7's that I'd end up with a 12AU7 back in Crack. But seem to be enjoying the 12BH7's right now. Nothing fancy, I have a few GE's, RCA's and Sylvanias. I like both the RCA and Sylvanias. Been listening to the Sylvania for a while now. I need to drop one of my preferred 12AU7's back in now and see whether my initial preference for the BH7's holds up. I think it probably will but the Holland Amperex (or maybe even the GE) may give it a run.
Yeah, sorry- I should pay more attention to the dates. You know I keep putting the 12BH7 in and it just does not call me back like the euro-tubes (amperex BB's, mullards, tellefunken, seimens chrome plates), and some of the 6sn7's do (especially the rusky tube). I got mine NOS-NIB (1968 RCA). Would a longer burn-in than a couple hours help improve the dynamics significantly? What music do you mainly listen to? Though my tastes run pretty darned eclectic.
I kinda favor a tubey sound which may be my attraction to the 12BH7 in Crack after I added the FPIII with 6SN7's. But I listen to a lot of electric blues, as well as classic hard rock and a good deal of metal (mostly classic). I was in my late teens and 20's during metals hey-dey and it hasnt left me eventhough Im pushing 50. I do listen to some jazz now and then but on the Radio on the other system. I dont own a single jazz LP or CD I dont think.
