Tube Rolling w/Crack

[Paul Birkeland]

You can run that Mullard in the Crack with no 6080, then measure the voltages at T1 and T5.  If they are 70-90V, you have a 12AU7.

[JamieMcC]

You can run that Mullard in the Crack with no 6080, then measure the voltages at T1 and T5.  If they are 70-90V, you have a 12AU7.

Thanks Paul  that's a useful thing to know. It checked out and sounds ok at low/average levels but starts to distort quickly when the volumes turned up a bit. Listening to some Simon and Garfunkel live from New York city 1967 with it at the mo its not bad with the vocals and with the acoustic guitars. But its probably seen better days.

[JamieMcC]

I really like the Mullard cv4003 box plate with the TS 5998. When using a 6080 I like the RCA clear top. The previous is my first choice though.

+1 

5998 RCA clear top is a nice combo with the HD650 but is a touch tinny with the T1's I tend to match these with a Mullard ECC82.

I do have a Tung-Sol JTL 12AU7 early 1950's which pairs well with the 5998 and works well with both headphones above it still has that higher definition of the clear top that works well with the HD650 but doesn't sound tinny or over the top with the T1's .

I would like to try one of those Tung sol 12au7 black glass tubes. They seem to have good write ups and I am curious to how a more premium 12au7 tube will compare to the E80cc's which quiet a few like here.
 

[serpent68]

I recently bought a nice pair of Sylvania 12BH7 from ebay to try out in place of the Amperex 7316.  When I installed it, there was a loud buzzing sound on both channels.  Same buzzing sound with the other tube in the pair.  When I put back the Amperex 7316, everything was back to normal (thankfully!).

Anyone can help explain why there is a buzzing sound?  Is the 12BH7 not a drop in replacement in the crack? Or could both the Sylvania 12BH7 be faulty? By the way, I have the speedball upgrade and running a TS 5998.

[Grainger49]

This thread has 12AU7 equivalents in it.  It also applies to Crack.  The parameters on a 12BH7 is not the same as a 12AU7.  The 12BH7 is used as a regulator in the Eros.  Has someone suggested the 12BH7 in this thread?  Did it work for them?

http://www.bottlehead.com/smf/index.php/topic,1027.0.html

I see now that Caucasian Blackplate (Paul) recommends changes to the circuit if you use a 12BH7. 

Here: http://www.bottlehead.com/smf/index.php/topic,663.msg45798/topicseen.html#msg45798

[serpent68]

Thanks Grainger.  I've read the post from PB, and I also remembered reading about not needing the mod if the speedball is installed.

In any case, I was expecting that the worst case scenario would be a loss of sound quality.  Did not expect such a dramatic loud buzzing sound  .  Still wondering if the 12BH7 tubes are defective.

I also have a pair of Philips E80CC coming my way from Ukraine to try out as the driver tube.  Any advice on compatibility issues with the E80CC, and do I need to make any mod to the stock crack + speedball to accomodate it? 

[Doc B.]

Buzzing means there was a bad ground connection. It was probably bad contact of one or more of the tube pins in the tube socket. It's not because it was a 12BH7, more likely corroded tube pins or just a bad tube.

[serpent68]

Thanks Doc.  I checked the pins on both the 12BH7 and they look fine.  Its strange that both tubes had such a loud buzzing sound, even with the volume turned off.  The 7316 tube is totally silent, so I do not think its the crack.

Is there any way to check out the tube without plugging into the amp?  I don't have a tube tester and I'm reluctant to plug the 12BH7 back into the crack again for fear of damaging it... I'm totally in love with my crack and any damage to it would devastate me.

[Paul Birkeland]

Buy a different 12BH7.

[onelivewire]

Hey everyone, I'm the lucky new owner of a crack+speedball kit, and I need some advice! I'll be using the crack to replace my schiit valhalla, which I run along with some beyerdynamic t1s. Good recordings sound great thru the valhalla, but there is no forgiveness for poorly mixed treble, and darker tubes seem to fix this for the t1s (at least, on my roomie's darkvoice). I was wondering what tubes you guys might recommend for bringing out a bit of bass in the t1s, and especially curbing the treble. I've read through some of the posts here, and saw the Mullard ECC82 recommended for the t1s, along with the standard 5998. Is this a good start for the t1s? Are there other respected pairings for the t1s? Thanks much in advance, I am new to the forum, so I hope I'm not breaking any rules!

[Paul Birkeland]

For less treble, the newer Russian 12AU7's should help out a bit. Also, not using a digital source is potentially more helpful than any tube rolling.

[serpent68]

I have the Beyer T90 running with crack + speedball.  Currently using the TS 5998 with Amperex 7316.  Very nice and balanced combo, the T90 does not sound harsh at all.  The mids are full bodied and the highs are sweet, not shrill.  I've also tried the Siemens 12AU7 silver plates, but it tilted the T90 to the bright side a bit.

[JamieMcC]

I've read through some of the posts here, and saw the Mullard ECC82 recommended for the t1s, along with the standard 5998. Is this a good start for the t1s? Are there other respected pairings for the t1s? Thanks much in advance, I am new to the forum, so I hope I'm not breaking any rules!

I think its a great place to start and will be very good as a reference for future rolling. Let us know how you get on.

I am running the T1 Crack + Speedball with 5998 at the moment and had started taking a few notes to use as a base line for future choices, its in rather raw form at the moment as it

[onelivewire]

Thanks for all the replies guys! From what everyone's saying, it sounds like I'll be looking into those 5998s with the Mullard ECC82s for my first new set. As far as source goes, I always prefer to listen to vinyl when it's available, and generally there's no treble issue. However, most unsigned, independent artists don't have the money for pressing records so an enjoyable digital source is pretty necessary for me and my eclectic music tastes

Thanks again everyone!

[JamieMcC]

Can anybody help with identifying which variant or age of Mullard 6080 this is? I am positive its a Mullard as the older style edge and bottom of the shield logo is faintly discernible as are the 8 & 0. It has triple spiky mica and double halo getters each off of its own set of goalposts.

In the gap between the second and third mica there is some black plates shielding? It would be nice to know the correct name for this metal plate also.

(https://www.head-fi.org/image/id/5460695/width/900/height/900/flags/LL)

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fcdn.head-fi.org%2Fa%2Fa0%2F900x900px-LL-a053f8a2_036.jpeg&hash=74b305484ff63a1de093f4f4e99e8f93076caaf9)

(https://www.head-fi.org/image/id/5460640/width/900/height/900/flags/LL)

(https://www.head-fi.org/image/id/5460641/width/900/height/900/flags/LL)

Thanks if anyone can help.