[pdrm360]

Do you folks have any idea what the warmest sounding tube for Crack is? 

 

[Loquah]

Mullards are a good bet

 

[pdrm360]

  Mullards are a good bet

 
What about the power tubes?

 

[Loquah]

Mullards are available for both.

 

[dreame77]

Spent today 7 hours to do all soldering. Likely no mistakes. 
And yes, with Beyerdynamic T1 it sounds great!

 

[JamieMcC]

  Spent today 7 hours to do all soldering. Likely no mistakes. 
And yes, with Beyerdynamic T1 it sounds great!

 
Congratulations the Crack and T1 are a superb combination

 

 

[dreame77]

Speaking of soundstage size, HD700 with Magni is similar to T1 with Crack (with Magni it was too small). 
It's hard to imagine how big would become soundstage of HD700 or HD800 with Crack... 
 
And one more interesting thing: it is said that one need high-Ohm headphones...
BUT I have no problems and distortions with Denon D600 (actually I need to turn volume knob 1,5 more), and with ZMF mod Fostex t50rp (twice the volume of T1). 
 
May be it is due to maximum input power of headphones: D600 -- 1800 mW, t50rp -- 3000 mW ?

 

[Doc B.]

The issue isn't volume level. Lower impedance headphones will not be controlled as well in the bass region as they would by an amp with a lower output impedance. It's not like low impedance headphones won't work at all with a Crack. But if you do a side by side comparison with an amp designed for lower impedance headphones like a S.E.X. amp you will hear the differences.

 

[grausch]

  And one more interesting thing: it is said that one need high-Ohm headphones...

I have a set of Shure SRH 440s (32 ohm) and the 250 ohm DT 770s. If I listen to the SRH440s with my cmoyBB, they sound very analytical with a very flat frequency response. The DT770s with the Crack tend to have accentuated bass and perhaps some accentuated treble with a slightly recessed midrange.
 
If I listen to the SRH440s with the Crack, then the bass becomes very loose and flabby. I was quite amazed at the change in character. I definitely prefer the DT770s with the Crack.
 
On another note, I can use the DT770s straight out of the iPhone, I lose some volume, but otherwise they tend to sound OK. Not as good as out of the Crack, but not as bad as the SRH440s with the Crack. Edit: Should add that I listen at low volumes. At higher volumes, the Crack / DT770 combo sounds a lot better than straight out of the iPhone.

 

[Bacci]

  The issue isn't volume level. Lower impedance headphones will not be controlled as well in the bass region as they would by an amp with a lower output impedance. It's not like low impedance headphones won't work at all with a Crack. But if you do a side by side comparison with an amp designed for lower impedance headphones like a S.E.X. amp you will hear the differences.

 
Most Senns have an impedance peak around 100 Hz due to resonance, how does this impact control in the bass region by OTL amps (which need high impedance cans for best performance)?
If we take the HD598 for example with a nominal impedance of 50ohm, but with an actual impedance of > 120ohm in the 50-200Hz region: would that impedance peak mitigate the problem of controlling its low frequencies?
In other words, if the impact of a bad dampening factor is mostly heard in low frequencies, would these cans perform a little better than one would expect based on their 50ohm nominal impedance (even though they would still be a bad match overall)? 
 
Or is the impact of an impedance peak due to resonance to be understood differently?
 

 

[dreame77]

  The issue isn't volume level. Lower impedance headphones will not be controlled as well in the bass region as they would by an amp with a lower output impedance. It's not like low impedance headphones won't work at all with a Crack. But if you do a side by side comparison with an amp designed for lower impedance headphones like a S.E.X. amp you will hear the differences.

Thank you, now I get it!
Why do I liked D600 with Crack -- it has much less prominent bass, healing overall balance. 
 
But T1 with Crack is just awesome. The sound is stunning, I could not stop listening. May be it is due to my first experience with tube amps (Shiit Magni, Audinst mx2, Fiio e17 my previous)?
Highs and mids are so beautiful, clear and liquid like. On the other side, while bass is pretty good, but not at the level of mids and highs. I am wondering would it be healed by Speedball Upgrade?

 

[Keithpgdrb]

  I have a set of Shure SRH 440s (32 ohm) and the 250 ohm DT 770s. If I listen to the SRH440s with my cmoyBB, they sound very analytical with a very flat frequency response. The DT770s with the Crack tend to have accentuated bass and perhaps some accentuated treble with a slightly recessed midrange.
 
If I listen to the SRH440s with the Crack, then the bass becomes very loose and flabby. I was quite amazed at the change in character. I definitely prefer the DT770s with the Crack.
 
On another note, I can use the DT770s straight out of the iPhone, I lose some volume, but otherwise they tend to sound OK. Not as good as out of the Crack, but not as bad as the SRH440s with the Crack. Edit: Should add that I listen at low volumes. At higher volumes, the Crack / DT770 combo sounds a lot better than straight out of the iPhone.

Yeah, complete impedence mismatch with your 440's.  It should sound like crap on the crack, which apparently it does.  Read up on the amping requirements for these cans.  all of your observations are spot on.

 

[grausch]

  Yeah, complete impedence mismatch with your 440's.  It should sound like crap on the crack, which apparently it does.  Read up on the amping requirements for these cans.  all of your observations are spot on.

Yeah, I know. I was merely quoting dreame77 and providing some insight into the differences between high and low impedance cans with the Crack. My low impedance cans have loose bass, which is what Doc B also suggests.
 
It was quite an interesting test, as I did not expect the SRH440s to ever have uncontrolled bass.

 

[liamstrain]

   
Highs and mids are so beautiful, clear and liquid like. On the other side, while bass is pretty good, but not at the level of mids and highs. I am wondering would it be healed by Speedball Upgrade?

 
I'm not sure it will - what you are describing is pretty much what the T1s sounded like to me - not something to fix with an amp change, just their sound signature.

 

[dreame77]

   
I'm not sure it will - what you are describing is pretty much what the T1s sounded like to me - not something to fix with an amp change, just their sound signature.

 
To make it clear. The last phrase I wrote comparing change of sound after moving from Magni to Crack. Mids and highs changed a lot in a good way, but bass changed not to the same extent.