[syphen606]

Finally tried a couple different tubes in the stock crack.
 
Sylvania 6080WB, Phillips 6080WB and a RCA 6AS7G black plate. 
Sound differences don't seem huge but the Phillips 6080WB does seem to have a tiny bit more clarity in the trebles and top end. The 6AS7G takes the aesthetic looks for me Too bad looks aren't everything. Love the big tube.
 
The 6AS7G is much more microphonic, but as long as your not playing with the amp its good.

 

[lost&confused]

I've only had my amp a few weeks now and I've bought a tung sol 5998 and mullard CV491 12AU7 K61 ....this mullard is meant to be a really good tube but I prefer the stock tubes!  ...    it came with an RCA Jan 6080 and a hewlett packard 5963 (Orange writing) and I really like this sound,  The tung sol doesn't sound that good to me (odd me I know  it sounds heavy wooly bassy good detail but not so fun sounding kinda  like other amps I've tried  not tube amps.
 
Its the same with the mullard tube I like the hewlett packard more  
 
My bottlehead crack is stock but ordered the speedball which I'm not sure I'm gonna install now ..well for the moment.  I just love this combo I'm using now and I notice a massive difference when I change tubes on my crack all different combos.
 
The amps working really well I have no hums or crackles  its plugged into creative ZxR sound card on a  desktop computer sitting 1 foot away from the pc ,  I only have noise if I have the volume at max and its only faint.
 
I do have a small problem with noise if  the volume turned up really high (much higher than I listen tho)  If i scroll with my mouse on web pages I hear a static noise but it doesn't really bother me, its right next to my pc! its from my sourse soundcard.
 
 
Love this amp with stock tubes for now everything sounds ace on my old HD600's even music on youtube !
 
Thanks

 

[lost&confused]

And sotto you should build one!  Its really easy the instructions are excellent,  I've never soldered a thing before doing this amp    The pictures in the manual are great and its fun building her then when you wanna mod it you  no how.
 
Go for it"!!  Good fun

 

[Klots]

How about GE 6AS7GA with stock crack? Anyone uses one and can comment how does it sound? 

 

[sotto123]

  And sotto you should build one!  Its really easy the instructions are excellent,  I've never soldered a thing before doing this amp    The pictures in the manual are great and its fun building her then when you wanna mod it you  no how.
 
Go for it"!!  Good fun

 
I purchased an assembled one from a fellow head-fier last night

 
Do you guys know what wattage the Crack uses? I was going to get a transformer that can support up to 300w but it's probably unnecessary. They're more expensive and much bulkier too. Would I be good to go with a 75w or 100w one?

 

[lost&confused]

Lazy!    I think its 120v sotto  but dont quote me on that ...someone will come along and comfirm it.
 
Whats your crack had done to it then? speedball  upgrade ? You in the UK then ?  I was going to buy a pre built one from another member but decided to go for it!
 
 I'm really not sure I wanna install the speedball     I think I'll order the standard parts to put it back to standard if I dont like the speedball ...but everyone says it makes biggest difference installing the speedball.  But loads of ppl say the tungsol is great tube.....I'll  give the other tubes another try. 
 
Maybe the tungsol sounds better with the speedball upgrade but I've read that with the speedball you dont notice tube sound changes as much than with the standard crack.
 
have fun!

 

[Tequilasunriser]

I've read that with the speedball you dont notice tube sound changes as much than with the standard crack.

I've read this as well too, can anyone chime in with some science on this? Subjective info would be nice too.

I like the way my Crack sounds now, not sure I want to install the SB.

 

[skeptic]

There's nothing about the speedball to dislike, IMO.  Crack's overall signature stays the same.  You just get a blacker background, tighter bass, and reduced voltage sag.  Loading your tubes with constant current is never a bad thing in headphone amps.  
 
As I understand it, akin to running in class A, it reduces the amp's overall efficiency - so you're unlikely to see it in a whole lot of speaker amps, but it is a nice improvement to sq.

 

[sotto123]

  Lazy!    I think its 120v sotto  but dont quote me on that ...someone will come along and comfirm it.
 
Whats your crack had done to it then? speedball  upgrade ? You in the UK then ?  I was going to buy a pre built one from another member but decided to go for it!
 
 I'm really not sure I wanna install the speedball     I think I'll order the standard parts to put it back to standard if I dont like the speedball ...but everyone says it makes biggest difference installing the speedball.  But loads of ppl say the tungsol is great tube.....I'll  give the other tubes another try. 
 
Maybe the tungsol sounds better with the speedball upgrade but I've read that with the speedball you dont notice tube sound changes as much than with the standard crack.
 
have fun!

 
Yeah, I'm in the UK. Got myself one with the speedball upgrade and Sino 6AS7G as an extra. Really looking forward to how it will sound with my T1's, meant to be a great match.

 

[lost&confused]

Sure it will sound real nice with those headphones!  I've never heard the T1's but one day I'l try them, I'm big into comfort so important to me, the weight and cable  .  I was going to buy new headphones but thought I'd try this crack amp with all the hype I've read and glad i did  stopped me spending loads on new headphones.
 
Thanks Sceptic for the info think I'll install it when it comes  have time.
 
How you running the amp then sotto?  I must try and plug these into my record player some day but hardly ever use it now,  I love searching youtube for music  and have loads of mp3s , sounds really nice with my hd600s.

 

[Doc B.]

  There's nothing about the speedball to dislike, IMO.  Crack's overall signature stays the same.  You just get a blacker background, tighter bass, and reduced voltage sag.  Loading your tubes with constant current is never a bad thing in headphone amps.  
 
As I understand it, akin to running in class A, it reduces the amp's overall efficiency - so you're unlikely to see it in a whole lot of speaker amps, but it is a nice improvement to sq.

It doesn't have as much to do with efficiency loss from running class A (it's already doing that) as the need for additional supply voltage headroom, and that is only in the case where a constant current source is used with a voltage amp rather than a cathode follower like the Crack uses. For example you can put an output transformer primary or a plate loading choke above a traditional 2A3 voltage amp output circuit and have B+ supply of maybe 300V. If you use a constant current source instead you might need a 450V supply. That plate load CCS will need to dissipate additional heat beyond what the tube and cathode is dissipating, much more than a choke would running at a lower B+. But with a CF this is a non issue because the CCS is just standing in for the cathode load resistor. The only increase in dissipation is a wee bit for the bias string.
 
From a technical standpoint the main difference of using a C4S constant current source is an addtional 60dB or so of power supply ripple rejection (thus the descriptions of a blacker background) and a distortion curve that stays linear with increased power up to a point further than it would with a lower impedance load like a resistor or choke. So distortion comes in later, that is when the signal is a little higher than it would be without the CCS. And when it does happen distortion is at a high enough level that it is less subtle unless you are careful to keep that stage linear all the way up to where the following stage is distorting first, which is definitely doable. So if you keep the signal level such the the tube's output stays within the linear zone the amp sounds more dynamic - and that's pretty easy to do when you are running headphones. My opinion is that cathode followers don't really sound that great without a CCS under them to make them more linear and I much prefer a Crack with the Speedball. 
 
Anyway all of this hopefully helps to explain why the tube becomes less influential in the overall sonic signature when a CCS is used. It has less power supply noise for the tube to add color with, and it is running in a more linear fashion, i.e. closer to the ideal for the particular tube type, as the signal thru it increases. 

 

[Sonido]

Anyway all of this hopefully helps to explain why the tube becomes less influential in the overall sonic signature when a CCS is used. It has less power supply noise for the tube to add color with, and it is running in a more linear fashion, i.e. closer to the ideal for the particular tube type, as the signal thru it increases. 

Alas we come full circle to solid state where components should not impart its own sound.

 

[sotto123]

  Sure it will sound real nice with those headphones!  I've never heard the T1's but one day I'l try them, I'm big into comfort so important to me, the weight and cable  .  I was going to buy new headphones but thought I'd try this crack amp with all the hype I've read and glad i did  stopped me spending loads on new headphones.
 
Thanks Sceptic for the info think I'll install it when it comes  have time.
 
How you running the amp then sotto?  I must try and plug these into my record player some day but hardly ever use it now,  I love searching youtube for music  and have loads of mp3s , sounds really nice with my hd600s.

The T1's are actually pretty comfortable. I was coming from a Grado so pretty much anything would've been an improvement in comfort.
 
I pretty much only listen to music through my laptop, so I definitely need to buy myself a decent DAC. The thing is that we get ripped off so badly in the UK when it comes to this stuff. I'm interested in a Schiit Bifrost, but it costs £519 here, compared to $519 in the USA.

 

[lost&confused]

Thats great info Sir Doc thanks for taking the time.

 

[lost&confused]

yeah its bad with expense gear from the usa with duty,  I imported the Schiit Vali amp and payed about £30 duty. You can buy online with schitt USA website. 
 
Them usb dacs are meant to be good , also Bottlehead I heard are making a dac  released soon i think.