[Zashoomin]

   
They're used as a resistor.

 
They also show if everything is working. If they don't turn on than you know something is wrong. 

 

[whatthedac]

They're used as a resistor.

 
Thanks.  Excuse my ignorance in the subject, but why not just use a typical resistor?
 
Edit:  Zashoomin, that is a plus.

 

[Jmstrmbn]

Someone correct me if I'm wrong but I believe the LEDs are used to bias the voltage the tubes receive.  In older circuits biasing was done manually and often "wandered" in and out of the correct bias.  Thankfully, the LEDs negate the need for manual adjustment as the resistor changes so does the voltage the tube sees.  
 
I don't have much background in circuits just some light reading so this may be totally of base and is more or less my understanding of the matter.
 
Anyway hope it helps clear things up!
 
John

 

[netmask254]

My location China has a voltage as 220V. I heard Crack has a 240v version, is it also usable in my area without any sound quality loss?

Besides, can someone give a rough ship weight of Crack since I need to calculate the oversea ship cost. Thanks a lot!

 

[clowkoy]

You should have no problem running a 240-volt crack in your country.
You can go to the Bottlehead website, put a crack in the cart and it will calculate the shipping cost.

 

[Zashoomin]

   
Thanks.  Excuse my ignorance in the subject, but why not just use a typical resistor?
 
Edit:  Zashoomin, that is a plus.

 
Well they also are diodes so current can only run in one direction.  If that helps.

 

[Aeolus Kratos]

   
INDEED!
 
A few tube enthusiasts have opined to me that they found the Ken Rad 6C8G (RPs) to sound fairly similar to the (famed) Ken Rad 6SN7 (RPs).  Now, I've haven't had a chance to actually hear the highly regarded 6SN7 version.. but if the sound of the 6F8G variant is any indication, the 6SN7 version must certainly be something special.  The 6F8G's bass is definitely punchy and impactful.. w/ the focus being on the sub bass rather than the midbass.  The treble has a smooth, balanced (in reference to the midrange) presence and good depth  Treble is crisp & complimentary to the addictive bass and deep, engaging midrange.  It's certainly in the top two or three favorite tubes I've rolled into the Crack.

May I ask what are the rest of your favorite tubes? I'm using the Raytheon 6SN7 thanks to your recommendation which you posted about a month ago and I love it!
 
Just be curious if the Raytheon is still in your favorite tube list

 

[trentrosa]

Wow!

Finished my Crack today. I'm a first time diy guy and noob with the soldering iron. Luckily, the only mistake I made was a backwards rectifier, blew a fuse. Honestly I'm quite proud of myself.

With my HD650s, I first listened to some Waylon Jennings, Ronnie Milsap, and Allison Krauss, immediately noticing tighter bass and amazingly clearer instrument separation opposed to my fiio e11.

Very well done on the Crack Doc. B, wonderful investment.

 

[Zashoomin]

Wow!

Finished my Crack today. I'm a first time diy guy and noob with the soldering iron. Luckily, the only mistake I made was a backwards rectifier, blew a fuse. Honestly I'm quite proud of myself.

With my HD650s, I first listened to some Waylon Jennings, Ronnie Milsap, and Allison Krauss, immediately noticing tighter bass and amazingly clearer instrument separation opposed to my fiio e11.

Very well done on the Crack Doc. B, wonderful investment.

 
Congrats man and enjoy.  Once the DIY bug bites it doesn't let go.  Don't say I didn't warn you 

 

[brunk]

   
Congrats man and enjoy.  Once the DIY bug bites it doesn't let go.  Don't say I didn't warn you 

 
LOL i still don't have my crack complete yet because of some parts i ordered went missing and are now on backorder. However, I now have a DIY Lightspeed Attenuator and First Watt F5 clone in the works. I'm in parts up to my elbows! 

 

[amcananey]

How much is the Lightspeed? I assume there are multiple options, so if you could describe yours and how much it cost, that would be great.

Thanks,
Adam

 

[netmask254]

You should have no problem running a 240-volt crack in your country.
You can go to the Bottlehead website, put a crack in the cart and it will calculate the shipping cost.

Thanks for your advice!

 

[brunk]

How much is the Lightspeed? I assume there are multiple options, so if you could describe yours and how much it cost, that would be great.

Thanks,
Adam

 
I believe the original lightspeed cost around $700.
 
There are several different approaches you can take. It can range from $50 in a cardboard box, to $2k for a fully decked out unit. I spent about $250 on my project and that includes a remote control!
 
DIY LDR3X board from Tortuga Audio. I got it on promo sale for $195, I can't tell if it's still on promo or not because the site is currently down. All i needed to buy was a suitable power supply, steel enclosure (with enough space for addon board in future), chassis jacks (RCA/PSU), status LED, and some wire.
 
If you want to go full-blown DIY without remote you can get matched LDRs here. Soon as you go into remote control territory, Tortuga Audio is the better deal because most the work is done for you. If you would like an assembled unit that has a very good price with remote, the EVA 2 is a great choice, but who knows when it will be back in stock.

 

[amcananey]

Cool, thanks for the info and links!

Best regards,
Adam

 

[brunk]

Cool, thanks for the info and links!

Best regards,
Adam

 
No prob Adam 

 
My LDR unit has shipped, but I'm waiting on a back order from pcX to be able to complete BOTH my Lightspeed and Crack lol. I'm hoping it ships this week!
 
EDIT: LDR3X diagram picture below
 
 

Spoiler: LDR3X diagram