[jinrum8]

   
From what I've digested over the last couple of days searching for new tubes, each tube can offer different qualities in sound. There are a few output tubes (the bigger tube) that are already established as sounding really nice with the Crack. The best ones being the WE 421A and GEC 6AS7G, but those will run you over $200 each. A few of the input tubes (smaller tube) that are recommended are Mullard CV4003, Valvo 12au7, and CBS Hytron 5814a just to name a few. Those will range between $20 to $100. Also, some tubes sound really good together and some don't. The two tubes that are reasonably priced are Tung Sol 5998 (2nd best Output tube) and CBS Hytron 5814a (very good quality for its price) that I just recently ordered. I'm still awaiting on how it sounds. Now, I'm not expert in the vacuum tube rolling game so I cannot tell you how any of these sound, just what I've researched on to be the most popular combos. I realized tube rolling is a subjective experience so it will depend on your tastes as well and can only be determined by hearing it for yourself. Hope this helped!

I am now really enjoying the Chatham 2399 with the Mullard 4003 which I received yesterday. Awsesome! I will roll the 2399 with my CBS Hytron and others soon.

 

[Jimmy24]

  I am now really enjoying the Chatham 2399 with the Mullard 4003 which I received yesterday. Awsesome! I will roll the 2399 with my CBS Hytron and others soon.

I just received my Tung Sol 5998 yesterday but I wasn't too impressed with it with my stock 12au7 tube. It was a bit too flat to me. I'm glad you found the Mullard 4003 to your liking. I am still waiting on my CBS Hytron 5814a to come in the mail as well as some Amperex Bugle Boys 12au7's. I've always heard lots of great things about the Mullard 4003. There are quite a few variants of the 4003, which one do you have? 

 

[jinrum8]

  I just received my Tung Sol 5998 yesterday but I wasn't too impressed with it with my stock 12au7 tube. It was a bit too flat to me. I'm glad you found the Mullard 4003 to your liking. I am still waiting on my CBS Hytron 5814a to come in the mail as well as some Amperex Bugle Boys 12au7's. I've always heard lots of great things about the Mullard 4003. There are quite a few variants of the 4003, which one do you have? 

I got this from my brother for Xmas and he got it from ebay. Not sure which variant. On tube are the letters 000-4003 CV 4003 KODDK 85-09. Sounds great though if you like warm lush sound.

 

[Jimmy24]

Did anyone here feel like the Speedball didn't make the Crack sound that much better? When I heard the Crack w/o Speedball it sounded very good. The separation was there, songs like Gravity by John Mayer and 1234 by Feist really shined with all its acoustic instruments. I felt like that Speedball gave better separation in instruments but the sound imaging for me was more 2d than the Crack. I'm hoping this has something to do with the tubes so hopefully the sound changes when I hook up an Amerex Bugle Boy or CBS Hytron into it. Maybe I was expecting too much but I was slightly disappointed with the upgrade. Maybe I'll have to take out Speedball again and see if my opinion on it remains true. 

 

[Jimmy24]

So I had another listening session tonight with my Tung Sol 5998's with the stock tube. I want to take back what I said about it sounding flat. The instrument separation and 3d imaging is all there. I guess I needed a day to really relax my ears. I think yesterday I was stressed out and doing a bunch of other things while listening to music so that probably influenced my opinion on it. I find them really amazing. I was listening to Fleetwood Mac's self-titled album and everything just sounded so good. I also tried listening to it on a lower volume and it made much more of a difference. I can't wait to roll different tubes with the 12au7's. I'm really diggin the 5998's. 

 

[JamieMcC]

  Oh crap... Missed the deal for these pair:
http://www.ebay.com/itm/Pair-Tung-Sol-12AU7-12AU7A-ECC82-Vacuum-Tubes-Very-Strong-/321609528392?pt=Vintage_Electronics_R2&hash=item4ae16bf448&rmvSB=true&nma=true&si=dUjiHdRDBeloa%252BQ0zXgDQGEZTlQ%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557
 
Any similar deal? I couldn't find one.

 
Here is a option for you I contacted and checked with the seller who confirmed the four brown box's with 5814A and 12au7 marked in pen are Tung-sol JTL tubes I was thinking about snapping up all four but shipping to the UK makes them to expensive for me.
 
http://www.ebay.co.uk/itm/RCA-JTL-12AU7-vacuum-tube-/301146315622?

 

[dxanex]

  Did anyone here feel like the Speedball didn't make the Crack sound that much better? When I heard the Crack w/o Speedball it sounded very good. The separation was there, songs like Gravity by John Mayer and 1234 by Feist really shined with all its acoustic instruments. I felt like that Speedball gave better separation in instruments but the sound imaging for me was more 2d than the Crack. I'm hoping this has something to do with the tubes so hopefully the sound changes when I hook up an Amerex Bugle Boy or CBS Hytron into it. Maybe I was expecting too much but I was slightly disappointed with the upgrade. Maybe I'll have to take out Speedball again and see if my opinion on it remains true. 

I had both a Speedballsless Crack and a Speedball'd Crack at one time and A/Bing them using the HD 650 and HD 800 I honestly didn't hear any clear night and day differences. To me the differences were subtle at best.
Putting in a Tung-Sol TS 5998 on the other hand and the difference was much more clear. Particularly in the low end and mids. The bass was much more detailed and controlled opening up the soundstage a bit more, and the mids were smoother and placed more forward- even in the non-Speedballed Crack the results were the same.
 
Now I feel like it's much easier to recommend the TS 5998 as a substantial upgrade to the stock Crack, rather than the Speedball. If I did it all over again though I would skip the Speedball and go straight for the TS 5998. Of course, this is IMO and YMMV.

 

[atomicbob]

  So I had another listening session tonight with my Tung Sol 5998's with the stock tube. I want to take back what I said about it sounding flat. The instrument separation and 3d imaging is all there. I guess I needed a day to really relax my ears. I think yesterday I was stressed out and doing a bunch of other things while listening to music so that probably influenced my opinion on it. I find them really amazing. I was listening to Fleetwood Mac's self-titled album and everything just sounded so good. I also tried listening to it on a lower volume and it made much more of a difference. I can't wait to roll different tubes with the 12au7's. I'm really diggin the 5998's. 

Listening at lower sound levels has three benefits:
 
1. less listening fatigue for long sessions, lower risk for hearing threshold shifts and damage
2. electroacoustic transducers (drivers in headphones) make smaller excursions thus remaining in a more linear range of operation
3. amplification elements (tubes) also remain in a more linear region of operation
 
All three add up to much lower distortion.

 

[JamieMcC]

 
I had both a Speedballsless Crack and a Speedball'd Crack at one time and A/Bing them using the HD 650 and HD 800 I honestly didn't hear any clear night and day differences. To me the differences were subtle at best.
Putting in a Tung-Sol TS 5998 on the other hand and the difference was much more clear. Particularly in the low end and mids. The bass was much more detailed and controlled opening up the soundstage a bit more, and the mids were smoother and placed more forward- even in the non-Speedballed Crack the results were the same.
 
Now I feel like it's much easier to recommend the TS 5998 as a substantial upgrade to the stock Crack, rather than the Speedball. If I did it all over again though I would skip the Speedball and go straight for the TS 5998. Of course, this is IMO and YMMV.

I have AB-ed  the two together as well and came to a similar conclusion that the superior sonic ability of the higher tier tubes some what compensates for the lack of speedball.  Certainly I would rather have a Crack without speedball compared to no Crack at all and no one should be put off by purchasing a Crack because it does not have one fitted its a easy upgrade to retro fit if the urge is felt later.
 
There are to my mind a couple of trade offs with the speedball.
 
This first one is a bit subjective but I will throw it out there for comment.
 
It felt to me as if some of the raw dynamics a stock Crack has were dialled back just a fraction.
Its well reported the effects of tube rolling can be slightly diminished (imo the effects of rolling are still easily noticeable just dialled back a fraction).
The increase gain with the speedball fitted can make noise related problems with tubes or RF/mains interference more noticeable. These are frustrating but often easily sorted with a little time spent methodically chasing down the cause and rerouting, moving to shielded cables, optical instead of USB etc.  

 

[Doc B.]

From a theoretical standpoint, without the Speedball you will see distortion occur at a lower power level than you will with the Speedball. That is to say, the tube will stay more linear to a higher power level with the Speedball. The distortion that arrives earlier in the stock configuration progresses more gradually, and allows the Crack to work somewhat like a compressor. The Speedballed Crack stays clean to a higher power level, but transitions into distortion more abruptly.

So it may sound like the stock Crack is handling transents more gracefully. It is. However those transients are actually more clean in a Speeballed Crack, as long as the level is kept below total harmonic distortion of, say, 5-10%.

 

[JamieMcC]

Interesting Doc thanks for that clarification.

 

[pedalhead]

Just ordered a Crack today. Total newbie to DIY but hoping to have it ready for the UK meet in April 

 .

 

[rock-solid]

First step is done - Crack is up and running.
 

 
 

 
All done in 3 relaxed evening sessions.
The wooden case is only taped together as the woodwork will be done in spring (have the tools in my summer house and want to smoke the wood - too cold outside for that).
The wiring looks a bit like spaghetti explosion because of the fly leads for the output caps and the longer input wire tor the stepped attenuator coming.
But it passed all tests on first try and is dead silent.
Now it´s time to burn in, especially the tubes before any critical listening.
Of course I had a sneak preview with my old DT990 - oh Lord, that sounds promising...
Next steps: burn in, waiting for the new DAC, play around with tubes. And listen till dawn while sleeping time reduces to the half...

 

[bigfatpaulie]

  First step is done - Crack is up and running.
 

 
 

 
All done in 3 relaxed evening sessions.
The wooden case is only taped together as the woodwork will be done in spring (have the tools in my summer house and want to smoke the wood - too cold outside for that).
The wiring looks a bit like spaghetti explosion because of the fly leads for the output caps and the longer input wire tor the stepped attenuator coming.
But it passed all tests on first try and is dead silent.
Now it´s time to burn in, especially the tubes before any critical listening.
Of course I had a sneak preview with my old DT990 - oh Lord, that sounds promising...
Next steps: burn in, waiting for the new DAC, play around with tubes. And listen till dawn while sleeping time reduces to the half...

 
 
Looks great!!  A bottle of Laphoraig Quarter Cask will elevate a listening system to astounding levels 

 

[JamieMcC]

Nice job and a good idea to have your build all prepped up ready for your intended mods. I'm looking forward to seeing what you plan on adding next.