[gwitzel]

  My amp is microphonic to some extent with many of the tubes I've tried for input and output.  My 5998 is a bit microphonic like that too. It's fine for listening. I only paid $60 for mine though. 

 
 

  I wouldn't worry about the microphonics unless you're in an environment where the amp gets bumped often and you can hear it.
 
As far as the sound goes, the 5998 sound signature is very subjective. It's got a lower output impedance so bass typically is tighter and better controlled. I also think it sounds more analytical than other tubes and results in a more detail. It also means it sounds more like solid state than other tubes which some people like and other don't. I've worked with solid state most of my life so I can appreciate what the 5998 brings to the table, but it also distances you from what most like about tubes. I've grown to like the warm signature and musicality of tubes and these days my favorite output tube is the Bendix 6080WB slotted graphite. A close second are the Sylvania Gold Brand GB6080 and Cetron 7236. These tubes all offer a warmer sound with a fat sounding bass, which I think pairs well with the HD800 which are known to be quite analytical and a little thin in the bass. 

 
Thank you for the reply, this is reassuring. The seller also confirmed that light microphonics are normal and might become better with time. However, it is very light indeed so I will not worry.
 
I felt that the stock tube had a nice timbre and was really pretty good. I am curious to see how I like the TS 5998. Unfortunately, I did not really have time to listen to it carfully. I will know more in 3 weeks when I am back home. After my last mod I had the sense of incredible channel speparation and clarity, but in loud orchestra moments it sounded a bit direct and dense, and the channel separation sounded a bit artificial. I hoped for a bit more transparancy in those dense moments, and more spacial coherence.
 
However, already with the stock tube the presentation was so real. My chain is:
 
Mac/Audirvana -> Schiit Wyrd -> Singxer F1 -> Schiit Gungnir MB BNC-input -> Bottlehead Crack -> HD600/650.
 
I love that I could build this myself for this price. The American audio community is awesome (says the German)

 

[Doc B.]

Tapping a hot tube with your fingernail might damage your fingernail, but unless your fingernail is a like a sledge hammer it's not going to harm a tube like the 5998. A 6080WA was designed for twenty 450G hits ferchrissakes. 

 

[gwitzel]

  Tapping a hot tube with your fingernail might damage your fingernail, but unless your fingernail is a like a sledge hammer it's not going to harm a tube like the 5998. A 6080WA was designed for twenty 450G hits ferchrissakes. 

 
Haha, I thought so... twenty 450G hit? So I still have 18 to go?
 
The web is full of strange opinions, sometimes very tough to sort out when you deal with technology that is new to you.
 
However, the Crack is a great set and I had incredibly much fun building it! Thank you!

 

[networkn]

I have a quick dumb question. I just added my speedball to my crack, and am about to power on for the first time. Instructions mention volume to lowest point, but the issue I have and have always had without turning it on, is how do I tell what is lowest? I didn't (stupid) mark this in prior occasions for some reason, but will do so now. 
 
How do others mark it as such? is there a "nice" way that looks good?

 

[Tom-s]

I don't have it marked. It's just the point where the volume pot is all the way to the left and stops.* Don't know how to describe this. 
Don't plug anything in but the powercord.
And never turn it on with a headphone connected. I leave it on for +-30 sec - 1 min before plugging in my headphones.
 
Should mention i removed my volume pot altogether and use a pre-amp, so my crack powers on at maximum volume every time without any problems.

 

[networkn]

  I don't have it marked. It's just the point where the volume pot is all the way to the left and stops.* Don't know how to describe this. 
Don't plug anything in but the powercord.
And never turn it on with a headphone connected. I leave it on for +-30 sec - 1 min before plugging in my headphones.
 
Should mention i removed my volume pot altogether and use a pre-amp, so my crack powers on at maximum volume every time without any problems.

 
Hi. 

Thanks for the reply. Left viewing from which side?

 

[Tom-s]

Anticlockwise

 

[networkn]

  Anticlockwise

 
Are you saying, if the RCA's are top left, and the volume knob is bottom left (headphone jack bottom right), then turning the knob all the way anticlockwise, will be at it's quietest (IE 0) and all the way clockwise would be say 10?

 

[Keithpgdrb]

Are you saying, if the RCA's are top left, and the volume knob is bottom left (headphone jack bottom right), then turning the knob all the way anticlockwise, will be at it's quietest (IE 0) and all the way clockwise would be say 10?

Yes. Works like every other volume in the world.

 

[networkn]

Yes. Works like every other volume in the world.

 
THANK YOU for taking the opportunity to make me feel extra stupid by using SARCASM! It's a fantastic way for me to start my week!

 

[networkn]

So I installed my speedball upgrade over the weekend, voltages all matched except :
 
19 - Reads 80v (Should be 0)
20 - 0 (Should be 206)
 
Apparently my version of the manual doesn't reflect an error which says measurement of 19 isn't relevant (no need to test) and 20 is supposed to be zero. (0v)

 

[JamieMcC]

  So I installed my speedball upgrade over the weekend, voltages all matched except :
 
19 - Reads 80v (Should be 0)
20 - 0 (Should be 206)
 
Apparently my version of the manual doesn't reflect an error which says measurement of 19 isn't relevant (no need to test) and 20 is supposed to be zero. (0v)

 
In the Crack section on the BHF there is a sticky on Crack manual corrections
 
http://bottlehead.com/smf/index.php?topic=657.0

 

[networkn]

Would anyone who has installed their speedball upgrade say that sound was more sibilent afterward? 

 

[deserat]

  Would anyone who has installed their speedball upgrade say that sound was more sibilent afterward? 

 
Didn't notice more sibilence but my 12au7 was bad so I upgrade that at the same time. 

 

[networkn]

Hi. 
 
Did anyone do this mod: 
 
http://bottlehead.com/smf/index.php?topic=2946.0
 
Who would mind photographing it, as I can't really understand exactly what is required. 
 
Also sorry I haven't read through the 523 pages of this thread, but is there a consensus on what valves to buy as a must-do upgrade. I am not particularly budget sensitive but also don't want to spend stupid money either. I guess max $100?
 
It would need to be plug and play though, I am done soldering my unit for a while.