Tube Rolling w/Crack

[nick-seattle]

This is for anyone with experience using the 12AX7. Any preferred brands? NOS or Current production? Just purchased a used Jolida FX tube Dac that I am modifying and is slated for my bedroom system. It uses 12AX7s in the output.

Cheers,
Shawn

Depends on what you want to get out of your sound: Amperex - balanced & sweet; RCA - warm & rich; Mazda - bright; Mullard - warm & relaxed; Telefunken - precise.

Here is a good write up:
http://www.watfordvalves.com/cgi-bin/documents/testreport_2.pdf

You also might want to try 5751 - there are some gems in the stack - but again depends on the sound you want to get.

I have a few of them next to my amp - and swap them depending on music I want to play.

[Noskipallwd]

Thanks guys, the 5751 has less gain than the 12AX7 IIRC.

Cheers,
Shawn

[nick-seattle]

Got 5998 tubes today. They tested quite good at 95%, but I have a very basic tester, but at least it tests as good as any other 6as7s that I got. Heats up quickly and doesn't have noise. So all is good.

Now, about the sound. All the "rumors" about SQ getting better with the tube are true It feels that another layer has been added to the sound. It sounds sweeter than Svetlana and more transparent and dynamic than the 6as7. If I can compare the 3 tubes to 12ax7: Svetlana is like Telefunken - clear etched sound, RCA is like... RCA warm and juicy, but not very transparent - also noisier than the other two; Tung-Sol is like Mullard - very transparent and dynamic, but relaxed.

BTW, if you are looking for a dark sounding tube with incredible warmth and juiciness that rivals even RCA, you should try Westinghouse 12au7 with carbon black plates. In the article below, I put a few steps how to ID the real WH compare to WH branded RCA tubes:
http://tubemaze.info/westinghouse-12au7-carbon-plates/

They pop up on Ebay once in a while.

[jrihs]

Very informative and nicely articulated, thanks! Where did you find the 5998's (pm me please)? All I find on e-bay are questionable. Fact is I just won one for 50 bucks and am very skeptical...for one, nobody else bid! There are some from England but he wouldn't give values on single tubes when asked. Only that they all range from 80-100% Maybe I should gamble once more...

By the way...those westinghouse 12au7's in your link are on e-bay...same background, same toobs. http://www.ebay.com/itm/3ea-12AU7A-1ea-12AU7-Vintage-Westinghouse-Radio-Tube-/140665492681?pt=Vintage_Electronics_R2&hash=item20c05114c9

[nick-seattle]

Very informative and nicely articulated, thanks! Where did you find the 5998's (pm me please)? All I find on e-bay are questionable. Fact is I just won one for 50 bucks and am very skeptical...for one, nobody else bid! There are some from England but he wouldn't give values on single tubes when asked. Only that they all range from 80-100% Maybe I should gamble once more...

By the way...those westinghouse 12au7's in your link are on e-bay...same background, same toobs. http://www.ebay.com/itm/3ea-12AU7A-1ea-12AU7-Vintage-Westinghouse-Radio-Tube-/140665492681?pt=Vintage_Electronics_R2&hash=item20c05114c9

I got them from Ebay - I guess I got lucky I put the max bid of ~$35 and won O_o. The issue with the tubes is that it's very hard to measure them with any tube tester - so the numbers you see on Ebay - I wouldn't trust - the tube could be much more performant than they state - you need to have a reference NOS tube (to get performance) and then see how they warm up. If they warm up fast and show close to the NOS tube performance, it's all good and they will likely last for a long time (hopefully). There is no guaranty even with NOS.

The Westinghouse in your link appear to be gray plates - so it's likely a rebrand. Here is the real version (not responsible if they are gone by the time you look at them )
http://www.ebay.com/itm/Westinghouse-12AU7A-Tube-Pair-82-and-92-/320904055498?pt=Vintage_Electronics_R2&hash=item4ab75f4aca

There is also a special military version of the WH tubes - marked as CWL (these sound the same as usual version, but they are selected & ruggedized):
http://www.ebay.com/itm/3-NOS-Westinghouse-by-Tung-Sol-Long-Black-Plate-FAT-D-Getter-JAN-CWL-12AU7-Tubes-/120911863648?pt=Vintage_Electronics_R2&hash=item1c26e89f60

They are getting kind of pricey and not because of my review

[nick-seattle]

So here is another interesting finding - I already discovered it with the other amps, but rediscovered it with Crack

Tube rolling results are very dependent on the output tube (6as7). I had the same experience with Dared 300B & McIntosh 275 (even driver tubes and cathod followers prevented a tube to shine if they were not transparent enough). If I put output tubes that are not transparent enough, all rolling experience is screwed up. All tubes sound the same because output tubes affect sound so much, so the more transparent the output tubes the better.

Now, in one of my first thought stated that rolling with Crack is hard - I have to admit I was absolutely wrong. Rolling is only hard when Raytheon (6080) or Svetlana or RCA are used as output tubes. With 5998 it's a new world, the amp is so responsive to rolling (I don't have Speedball - I have prejudges against SAND) that each new tube is like new experience.

As I mentioned before I modified my Crack to work with 6SN7, 12au7, 12ax7 family. Check out the photo
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Ftubemaze.info%2Fwp-content%2Fuploads%2F2012%2F05%2FDSC03682-1-768x1024.jpg&hash=49a006ca90cf64bd2d756e26f64e4889a6cefc38)

There is a switch now that switches between anode voltage and bios of medium-mu (12au7 & 6sn7) and high-mu tubes (12ax7). WOW!!! New tubes that I rolled were just absolutely gorgeous. I try to post my experiences on www.tubemaze.info every day.

I understand that 12ax7 is not the best tube for headphones - whatever! There are some tubes in the family that can't be matched my any other tubes. For example, I was selling my Telefunken 12ax7 Smooth plates Selects on ebay because although they were for my MC, I couldn't hear a difference between regular smooth plates and Selects - speakers, as you know, are not the best media to communicate nuances of music. With the modification I finally understood why the freaking tube costs $200 (I didn't buy it, but inherited with the MC). Anyways, if you are into discovering new dimensions of music, 12ax7 & 5751 is a must. So make the mod!!! It's super easy.

[nick-seattle]

You can hate me and say that Mazda doesn't have the real tube sound, but it doesn't sound like SS either - it has a unique sound to it and for some music I'm just absolutely in love with the tubes. JTake for example, Diana Panton - she has such an absolutely unique voice - imported from Canada - hard to get here CDs, but they pop up on Amazon & Ebay. Mazda makes her CDs sing like no other tubes, so... before you reject them, try them - you will be amazed, with the right music (Diana Panton for example . The freaking things could be expensive - but that's the beauty of Crack - it only takes one tube in preamp

[Beefy]

I try to post my experiences......

You know, I probably wouldn't mind reading your great walls of text so much, if you didn't keep pimping you own personal website all the time. You may not be selling anything, but the PPV ad at the bottom doesn't really bode well.

[nick-seattle]

I completely forgot about the ad. It was an experiment I did some time ago, but since it was all the way on the bottom, it completely slipped my mind. The ad is gone now.

The site is really designed with a single purpose in mind - to help others with tube selection. I think a claim that tubes sound different in different amp is somewhat misleading. There are great tubes that sound great everywhere. There are bad tubes that sound horrific everywhere. I went through the majority of the tubes through now 5 amps (building my 6th amp now) and the sonic results are quite the same. There are cases when circuitry doesn't allow the tube to shine, but it still sounds great. When I started with tubes, I was absolutely confused and lost - there are so many choices and the most obvious ones are very expensive, but there are superb tube for a reasonable price, but they are fairly unknown. So I invite everybody to contribute and help everybody else.

[nick-seattle]

I'm in the Output tube rolling mode right now The first one I got was Bendix 6080WB (waiting for 7236 & Sylvania GB 6080). It looks like Crack was shipped with Bendix before, but then changed to other tube - not sure what the reason was. In general, I felt that this tube provided a better balance across the spectrum compared to 5998. Tung-sol does have more powerful bass, but it comes at an expense of overemphasizing LF and making things much darker than they should be in reality - you can balance it by using brighter tubes - RCA 12au7 Long Gray Plates - without loosing creaminess. On the other hand, I felt that Bendix provided more clarity in instruments - each instrument was much easier to separate compared to 5998. There was a significant improvement in clarity when playing Chantal, Marga Etoile(Sopran)-Lulle, Lullay And Lullabye. The sound is definitely thinner than 5998, but more balanced & dynamic. One negative, the darn thing is hard to roll - it gets extremely hot!!! but it's built like a tank,  the plate structure is very cool looking and a slit in the middle  plates - is like a window into a soul

Had anybody else try the two tubes? Any impressions?

[Laudanum]

It's got to be a relative thing if you think that the 5998 overemphasizes the LF.  I dont have a Bendix to compare but dont find that to remotely be the case comparing the 5998 with any of the 6080's or 6AS7's that I do have, including the Svetlana 6H13C.

[nick-seattle]

It's got to be a relative thing if you think that the 5998 overemphasizes the LF.  I dont have a Bendix to compare but dont find that to remotely be the case comparing the 5998 with any of the 6080's or 6AS7's that I do have, including the Svetlana 6H13C.

That's quite true. When I use 5998 or 6h12c and play Melody Gardot she sounds much older than she is. Also, low notes on the piano sound much lower than they would with a real piano - I asked my wire to play a piano passage for me - and then I run to listen to the same passage on with my amp the results - with Bendix came much closer to the real piano. This definitely depends on the input tube, but in both cases I used Mullard 12au7 Long Plates (BTW, this is a killer tube - quite dark, but the amount of nuances it can communicate!!!). My headphones are quite balanced (Sennheiser HD650), so they shouldn't lean towards LF. BTW, my goal is to get the amp as close to real sound as possible (SS can't produce natural sound as it would be in reality -way to sharp) - which is not exactly the vintage sound that a lot of people are buying tube amps for. I do enjoy vintage sound with some music, but definitely not all. I know how to get the vintage sound - Westinghouse 6SN7 or 12au7 get me right there. With natural sound... I'm still looking, but Bendix gets me a step closer.

I've been using Bendix for 2 days now. The amp gets much hotter than with other tubes. So far very pleased. Anybody needs 5998??? Just kidding - I'm planning to keep the tubes. On the other note, I've heard that 7236 is very close in sound to Bendix - Very dynamic tube. I should get it this week and will report on my findings. One is selling right now on ebay for $19. I bought from the same seller, but he puts them out one at a time.

http://www.ebay.com/itm/Cetron-7236-Military-Vacuum-Tube-PN-3213999-/320906292086?pt=Vintage_Electronics_R2&hash=item4ab7816b76#ht_1254wt_1168

[/quote]

[Laudanum]

7236 is supposedly a computer rated 5998A (not 5998).  The 5998 and 5998A are a bit different tube.   Quite a bit of info out there for both the 5998a and the 7236 and it's a mixed bag.  I havent had the interest to try either and the reviews havent swayed me.   But it's cool that you are trying everything that you can get your hands on.  Rolling is fun but I have to set my limit.   Money being spent elswhere lately on other things that, for the time being are getting seemingly scarcer (and expensive) that NOS vac tubes ... It is another Presidential election year and demand for items necessary for one of my other interests always skyrockets during election years.  I'll leave it at that 

[Lee Hankins]

I have been playing around with the 7236, 6336A, and 6528A lately.  Like the sound of the 6336A/6528A over the 7236, not really much difference here, if any at all.  The 6528A has become my tube of choice, but I really believe that it is because I like the looks of this extremely rugged tube over the other two (6528A is just slightly larger than the 6336A).  These tubes run extremely hot!!!

[nick-seattle]

I have been playing around with the 7236, 6336A, and 6528A lately.  Like the sound of the 6336A/6528A over the 7236, not really much difference here, if any at all.  The 6528A has become my tube of choice, but I really believe that it is because I like the looks of this extremely rugged tube over the other two (6528A is just slightly larger than the 6336A).  These tubes run extremely hot!!!

So this is interesting. 6528 * 6336 draw 5A of heater current, but structurally they looks similar to Bendix 6080 - that might explain why Bendix takes 15 seconds to start playing and gets everything hot. Although, it's very interesting that Bendix being marked as 6080 would draw more current. I would have to try 6528.