Tube adapters??

[mikek200]

Ah,OK Tubejack
Thanks for that clarification
I'm a little new to crack & the tubes,that can & cannot be used.?

Basically,what I'm trying to find out is...does the 6sn7,produce better quality sound,with all things being equal ,vs. the 12au7
My thinking,correct me ,if I'm wrong,or,coming from left field,is,that, due to the bigger physical size,the 6sn7 should produce bigger,better SQ?
Also,most of my 6sn7's,that I've purchased,are all made in the 50,60's..& jan labelled
Weren't the tubes ,made in that era..better quality,better sound? low noise??

With that being said,yesterday,I got delivery of another tube ,a Siemens 12au7 ecc82 triplemica ,,,the quality of sound with my HD800's & Crack, ,and tung-sol 5998 ,was so outstanding,_ I listened to it for almost 12 hours nonstop

Natural sound,
Great pics......the original tube that came with my crack,was from a "Conn" organ
Thanks for those links.

Any other input/advice ,will be greatly appreciated

Mike

[Paul Birkeland]

correct me ,if I'm wrong,or,coming from left field,is,that, due to the bigger physical size,the 6sn7 should produce bigger,better SQ

This is kind of a gnarly misconception.

The primary difference between a 6SN7 and 12AU7 would be ten years of technological evolution (6SN7 evolving into the 12AU7).  If you go backwards from the 6SN7, you'll find the single bottle 6J5, then the 76, 37, etc.

One way to judge the impact of physical size is to look at how much heat one of the plates can dissipate.  A 12AU7 can burn off 2.75 Watts, while earlier 6SN7's are rated to 2.5 watts (the GTB/A can do more). 

It's also worth noting that the overall geometry differences between the 6SN7 and 12AU7 lead the SN7 to have more stray capacitances, which may contribute to some of the observed sonic differences. 

IMO, the very best of the 12AU7 family edge out the 6SN7, but an average 6SN7 will sound a little better to me than an average 12AU7.
-PB

[mikek200]

  "IMO, the very best of the 12AU7 family edge out the 6SN7, but an average 6SN7 will sound a little better to me than an average 12AU7"

PB,thanks for your reply..

So,basically,size does not matter..
Key word here,might be ..edge out,.


I was guessing as much,& I'm assuming the very best of the 12au7's,might even be price prohibitive?...Lorenze, {if you can find one ?},matched & balanced Siemens tubes?
Dollar for dollar,the 6sn7,might be the way to go?

M

[Paul Birkeland]

Eh, the prices that tubes command can be circumvented to a large degree by buying used tubes with unusual labeling.  I see a few Mullard 12AU7's with non-Mullard printing on eBay for $15, that's a nice place to start.

When you move into Siemens, Telefunken, Amperex, and Mullard type 12AU7's, then the 6SN7's that can keep up become a bit more scarce. 

[mikek200]

Paul,
Thanks for your suggestion

I went on e-bay,& found a few tubes {12au7 }, that I might be interested in,.Amperexes Mullards,Brimar
These have odd labeling,but seem to be authentic..such as--Mullards ,made in India,and one or two others
Prices were low,& the readings were good-to like new...

Still waiting on my 6sn7 to 12au7 adapter..coming from China.

[Laudanum]

I've used the adapter to run 6SN7's in crack.  The adapters work well.   I ultimately built an FPIII with 6SN7's and use a 12AU7 or variant in Crack.   If I was running the Crack standalone, Im not sure where I would have ended up.  Most likely the VT-231 (6SN7) primarily but I also have some favorite 12AU7's as well as some of the 12AU7 variants and 12BH7.  Tube rolling can be fun 

[Lar]

Paul,
Thanks for your suggestion

I went on e-bay,& found a few tubes {12au7 }, that I might be interested in,.Amperexes Mullards,Brimar
These have odd labeling,but seem to be authentic..such as--Mullards ,made in India,and one or two others
Prices were low,& the readings were good-to like new...

Still waiting on my 6sn7 to 12au7 adapter..coming from China.

Yea I believe mine took the same boat when I ordered, must have taken 3- 4 weeks to get them. 

[mikek200]

OK,really no luck with dealing with Chinese adapters..or,6 week delivery times.
Maybe you guys can still help?

Here is what I am looking for:

a 9pin base to 6sn7 {on top} adapter...that plugs into my 12au7 input
Does anyone know,of a seller in the USA,or,someone who can build me one  ,in the USA?

Is this idea doable,safe?

Thanks
Mike

[mikek200]

OK found it..
Just in case anyone else may need one:

   http://www.ebay.com/itm/281031554093?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

[Laudanum]

Took less than 2 weeks for me to get those adapters from HK.  I think it was the same seller too.  They work fine.  Of course, YMMV on shipping time.

[dubiousmike]

thanks for the link and feedback on the hongkong seller Mike and Laudanum - I was on the fence about ordering from a non-US seller but did just order one up.  here's hoping it gets here in some relatively reasonable time frame!

[dubiousmike]

Well - finally received my 6sn7 adapter, and sadly I'm getting a bad buzz in the left channel (that increases in loudness as I turn up the pot).  With the pot at 0, no buzz is audible. 

I acknowledge that the problem could be my tube - but I only have 1 6sn7 on hand (a seemingly nice Sylvania vt-231 foil getter I picked up from tubemaze), so my money's on the adapter.  It has a hex bolt on the bottom.  Has anyone successfully taken one of these apart to check the connections? 

My amp continues to run beautifully with all of my other input tubes.

[Laudanum]

Never had the need to take one apart.  They had it apart to build it, shouldnt be too difficult, maybe just a loose wire/bad solder joint.

[Grainger49]

If the volume is at zero, and there is no buzz, then the problem is before the volume control.  The only things that are before the volume controls are the input RCA jacks and 3 pieces of wire (it may be four pieces of wire, but I remember the input wires being braided). 

Is the buzz in one channel?  It could be the interconnects.  Regardless, try reheating the solder joints on he inputs and the volume control.

[dubiousmike]

Thanks for the input laudanum and grainger.  The buzz is only in the left channel, but to clarify, I dont have any issue when running the amp with any of my many 12au7's or 12bh7's.   So I don't think the problem is with the amp, interconnects, etc. 

Gotta be either my adapter or 6sn7.  I'll have to see if I can open up the adapter later today.  I pulled the hex nut from the bottom, but it doesn't fall open immediately.  Maybe time to contact the vendor on ebay.