[audiojun]

My Bottlehead Crack is for sale check my signature. Hard to let this go, I have so many fond memories with it, but my wife wants me to sell it since I have 2 headphone amps at the moment.

 

[silentmoon]

I have never listened to any crack otl but I've been living with 6080 for years, tried all 6080 of all versions and countries and found that the best was 6h13c from old Soviet Union. They do not magic, they do not make colorations, they do sound fine and natural.

 

[chiggah]

Just bought my first amp - a used Crack + SB that comes with tubes

How are these tubes and what config should I use with the Sennheiser HD650 ? And how much these tubes worth ?

What upgrade should I be going for first ? Below are the seller comments

I have built this amp as carefully and meticulously as I can. The circuit is noise-free and all voltage readings are within spec.

A high quality Alps RK27 volume pot has been installed instead of the supplied, which has much better low volume tracking. The output capacitors have been installed on leads for easily upgrading to PIO or film capacitors.

The box is finished in "liquid amber" wood stain and clear polyurethane varnish. I will admit the varnish is not 100% smooth in places and could do with another coat. The chassis plate and transformer bell housing is finished in high-temperature rated matte black.

The following tubes are included:

Power:
RCA 6AS7G (x2)
Svetlana 6H13C (x2)
Telefunken 6080 (this one is a rebranded Sylvania)
Unfortunately all bar the Telefunken have slight microphonics

Input:
RCA 12AU7 (x2)
Phillips Miniwatt 12AU7
Brimar 12AU7 (x3, all different plates)
Electro Harmonix 12AU7

 

[JamieMcC]

How are these tubes?

RCA 6AS7G
Svetlana 6H13C
Telefunken 6080 (this one is a rebranded Sylvania)

Input:
RCA 12AU7
Phillips Miniwatt 12AU7
Brimar 12AU7 (x3, all different plates)
Electro Harmonix 12AU7

I would take the Svetlana and probably the if using hd650 then the RCA if its a clear top is always a good choice but not so good with other phones like byers.

 

[Aradea]

How are these tubes?

RCA 6AS7G
Svetlana 6H13C
Telefunken 6080 (this one is a rebranded Sylvania)

Input:
RCA 12AU7
Phillips Miniwatt 12AU7
Brimar 12AU7 (x3, all different plates)
Electro Harmonix 12AU7

I have the Brimar long gray plate and its a musical input tube.

 

[chiggah]

How does a 6BL7 compare to the 5998 TungSol ?

 

[chuckwheat]

  my wife wants me to sell it

but why!?

 

[audiojun]

  but why!?

I have no desk space, right now It's unused. I also need money for my twins that are about to be born soon. Also I recently built the Torpedo III and loving it 

 but in a way it's feels like it's the opposite of what the crack is all about, it uses output transformers and it's differential push-pull instead of single ended. I wish I could keep both because they sound different enough. The Torpedo III wins on dynamics and resolution but the Crack is better for musicality and smoothness.
 
edit: My crack doesn't have the full mods just only speedball. A fully modded out Crack or Crack2 should be on another level but I haven't heard it.

 

[Demoninja]

Hey all just wanted to confirm if this is the right part. I'm interested in upgrading the pot to a stepped attenuator but I'm not willing to pony up $150+ so I'm gonna go with a Valab. http://www.ebay.com/itm/Valab-23-Step-Ladder-Type-Attenuator-Potentiometer-100K-Log-Stereo-/301934856580?hash=item464cb84984:g:cekAAOSwo3pWgXR7 Is this the correct part? If it is the right part is there anywhere I can purchase it from for a similar price but faster shipping? I can't seem to find any place to get it besides eBay.

 

[JamieMcC]

  Hey all just wanted to confirm if this is the right part. I'm interested in upgrading the pot to a stepped attenuator but I'm not willing to pony up $150+ so I'm gonna go with a Valab. http://www.ebay.com/itm/Valab-23-Step-Ladder-Type-Attenuator-Potentiometer-100K-Log-Stereo-/301934856580?hash=item464cb84984:g:cekAAOSwo3pWgXR7 Is this the correct part? If it is the right part is there anywhere I can purchase it from for a similar price but faster shipping? I can't seem to find any place to get it besides eBay.

You have the right one, I haven't seen them for sale anywhere else other than on ebay I have used a several now in different projects. With the Crack you will probably need to braid up some new signal wiring as the Valabs hook up points are on its top and I think I needed a extra couple of inches of length after swapping out the stock pot. 
 
Importantly don't forget to bridge the two separate channel grounds on the top of the Valab together with a small piece of wire

 

[chiggah]

My crack is dead quiet at minimum volume up to about 1-2 o'clock on the knob. But when I turned off the music and maxed out the volume knob...around 2 o'clock there was some slight hiss...kinda like a white noise and grew louder as I maxed out the volume knob. 
 
Not complaining because I would never set the volume at 2 o'clock (too loud) anyways, but just curious what noise could that be ? 
 
Is that the hiss coming from the Asus Essence ST source ? That would be my guess
 
Would one method to tell is by disconnecting the RCA from the input on the Crack itself ? Please let me know what other methods I can test to determine the source of the sound.
 
However, I just found the below on the Crack FAQ page - so this is nothing to worry about ?
 
5.  When I turn my Crack all the way up, I hear some noise, is this normal?
Generally yes, there will be some noise with the volume control at its maximum level.  The amount of noise will depend greatly on the impedance of the headphones, but the important thing to remember is that this is well beyond a comfortable listening level.

 

[Demoninja]

 
You have the right one, I haven't seen them for sale anywhere else other than on ebay I have used a several now in different projects. With the Crack you will probably need to braid up some new signal wiring as the Valabs hook up points are on its top and I think I needed a extra couple of inches of length after swapping out the stock pot. 
 
Importantly don't forget to bridge the two separate channel grounds on the top of the Valab together with a small piece of wire

 
Thanks for the heads up on bridging the grounds and the potential need for rewiring. I plan on doing a pretty extensive rebuild of my Crack that already called for all new wiring.
 

 
However, I just found the below on the Crack FAQ page - so this is nothing to worry about ?
 
5.  When I turn my Crack all the way up, I hear some noise, is this normal?
Generally yes, there will be some noise with the volume control at its maximum level.  The amount of noise will depend greatly on the impedance of the headphones, but the important thing to remember is that this is well beyond a comfortable listening level.

 
If it's only noisy at volumes way way beyond what you would listen to it at I don't see why you would worry about it, just enjoy your Crack!

 

[Doc B.]

If the noise gets louder when you turn the volume up it's not coming from the Crack. It's coming from the gear ahead of it.

 

[Solarium]

Just grabbed several pieces of tubes at great prices on ebay:
 
TS 6080 - $38 (output)
CBS JHY-5814a - $20 (input)
Telefunken 12AU7 / ECC82 - $32 (input)
 
3 tubes for the price of 1 TS5998, not bad at all! Can't wait to finally do some tube rolling. I'm wondering if I should still even look for the 5998 at this point.

 

[Walderstorn]

Uuuhhh i would like to try that telefunken.