Tube Rolling w/Crack

[TurbOSquiD77]

So I was looking at 6SN7's and came across this:
https://www.tubedepot.com/products/sylvania-vt231-6sn7gt-1945

I feel as if one should be careful about who they buy from, and their pricing. Are these Sylvania's really worth this much? What are the typical TOTL 6SN7(GT)'s that are usually favored?

Regards,

-T

[calmiswar]

Hello All,

I recently purchased a 12AU7 Telefunken tube, the seller tests on a Maxi-Preamp 2. Between the 2 triodes, I see A has a gain of 15.5 and B has 17.2.
I saw this after I purchased, is this normal or have I purchased a lemon?

Thanks.

[elnrik]

So I was looking at 6SN7's and came across this:
https://www.tubedepot.com/products/sylvania-vt231-6sn7gt-1945

I feel as if one should be careful about who they buy from, and their pricing. Are these Sylvania's really worth this much? What are the typical TOTL 6SN7(GT)'s that are usually favored?

Regards,

-T

I got a pair of these off eBay for my Elise.  IIRC, they were $80 for the pair.

[Tom-s]

Hello All,

I recently purchased a 12AU7 Telefunken tube, the seller tests on a Maxi-Preamp 2. Between the 2 triodes, I see A has a gain of 15.5 and B has 17.2.
I saw this after I purchased, is this normal or have I purchased a lemon?

Thanks.

This is perfect! I've used Telefunken measuring 13 vs 8.5 and that tube sounded perfectly normal.

[calmiswar]

This is perfect! I've used Telefunken measuring 13 vs 8.5 and that tube sounded perfectly normal.

Thanks a lot for the reply! That is great to hear.

[Paul Birkeland]

I recently purchased a 12AU7 Telefunken tube, the seller tests on a Maxi-Preamp 2. Between the 2 triodes, I see A has a gain of 15.5 and B has 17.2.

That's a little less than 1dB of difference.  It will likely be a little audible, but not intrusive.  It's certainly not abnormal.

[calmiswar]

That's a little less than 1dB of difference.  It will likely be a little audible, but not intrusive.  It's certainly not abnormal.

Thank you. I was playing with the balance feature on my Fiio X3ii and I can't really tell the difference of 1 dB.
Just thinking, can I compensate for the dB difference in the input tube triodes using the balance feature?

[Lawrence Ho]

Thank you. I was playing with the balance feature on my Fiio X3ii and I can't really tell the difference of 1 dB.
Just thinking, can I compensate for the dB difference in the input tube triodes using the balance feature?

I have seen someone modified his crack so that there are two individual, separate rca channels, and two volume controls (alps blue velvet) of course.

If you are interested, I can quote the link here later when I am home.

Lawrence

[MIKELAP]

First time poster here. About using a 6SN7 in the Crack i got myself a 6sn7 to 12au7 adapter .it works alright but problem is sound level doesnt get very loud  is there a modification that has to be done to use this tube .i was under the assumption it would work ok with adapter kinda puzzled .i heard of guys using this tube .

[Doc B.]

We have not made the Crack with the intention of accomodating this kind of thing, so you are in the realm of experimentation here. It should have about the same gain. But not knowing how this adapter is wired, it's pretty much impossible for us to offer any guidance. Could be a worn out tube, could be a socket that is somehow not optimal, etc. If you can post voltage measurements we might be able to offer some suggestions.

[Paul Birkeland]

I have seen someone modified his crack so that there are two individual, separate rca channels, and two volume controls (alps blue velvet) of course.

Our first preamp kit, the Foreplay, offered two dual mono volume control pots as you described.  I built several over they years, and I found it extremely tedious and difficult to ever get the channels balanced, and once they were balanced, I would never really want to adjust the volume because then I would have to start over and rebalance the channels at the new level.

[Natural Sound]

First time poster here. About using a 6SN7 in the Crack i got myself a 6sn7 to 12au7 adapter .it works alright but problem is sound level doesnt get very loud  is there a modification that has to be done to use this tube .i was under the assumption it would work ok with adapter kinda puzzled .i heard of guys using this tube .

I wired my Crack amp to use a 6SN7 (no adapter). I have more gain than I can use with my Sennheiser HD600's. What kind of headphones are you using?

[MIKELAP]

Hi i am using a pair of Senns HD800S. I was told by this Chinese seller that these adapters worked in the Crack.win some lose some i guess . Thanks

[Tom-s]

I use a chinese ebay adapter for 6sn7's without problems. Voltages are within normal range using 6SN7's on crack+speedball.

[JamieMcC]

First time poster here. About using a 6SN7 in the Crack i got myself a 6sn7 to 12au7 adapter .it works alright but problem is sound level doesnt get very loud  is there a modification that has to be done to use this tube .i was under the assumption it would work ok with adapter kinda puzzled .i heard of guys using this tube .

I used a 6sn7 adapter in my Crack for a year or so and rolled a number of 6sn7 tubes and didnt find any that lacked volume using Beyer T1 or HD800 my adapter was essentially plug and play.  So its odds on that its either a problem with the adapter or the tube. Maybe get a inexpensive new 6sn7 to try. I do remember when looking into using the adapter myself that one or two Crack users on headfi were having noise issues with their adapters but mine worked fine from the off.