Crack;Bottlehead OTL
Mar 29, 2017 at 8:56 PM Post #8,356 of 12,304
The stock ones go pretty quick on ebay, though there are alot of 'em right now. Adding artistic flare as you are talking about could increase the price but require the right buyer, and as such make it a longer turn around. It's a pretty popular amp and there alot of people who simply don't want to build it ( so sad for them ).
This is a very thought out answer. I have seen basic ones fetch $450 to $500 but some have extra tubes. Hopefully a quartered oak furniture grade cabinet and copper helps but just cause I like the idea does not mean everyone will.:smirk:

If I do not end up with an extra amp I may just sell the cabinet ready to go for someone to upgrade their kit or finished amp.
 
Apr 2, 2017 at 9:55 AM Post #8,357 of 12,304
 For a while i've been using 6CG7 for my CRACK and i got tired of some 6CG7 tubes will hum with my crappy DIY adapter so i decided to put a switch between Pin 4 and Pin 9 i'am surprised how quiet those same 6CG7 that hum on my adapter.
 
 
Sorry for the crappy phone camera.

 

 
Apr 2, 2017 at 11:18 AM Post #8,358 of 12,304
   For a while i've been using 6CG7 for my CRACK and i got tired of some 6CG7 tubes will hum with my crappy DIY adapter so i decided to put a switch between Pin 4 and Pin 9 i'am surprised how quiet those same 6CG7 that hum on my adapter.
 
 
Sorry for the crappy phone camera.

 

Those are decent enough photos. I look forward to experimenting with various tubes to find those I like best and thankfully there is plenty of info out there describing what others have tried. The biasing LED is pretty obvious in the photo.
 
I must have ordered my kit in early March, so far no news on that shipment. I am still waiting for other parts but I did get 250 ohm headphones going that will match my build once I finish the cosmetics.
 
Apr 2, 2017 at 10:46 PM Post #8,360 of 12,304
Those are decent enough photos. I look forward to experimenting with various tubes to find those I like best and thankfully there is plenty of info out there describing what others have tried. The biasing LED is pretty obvious in the photo.

I must have ordered my kit in early March, so far no news on that shipment. I am still waiting for other parts but I did get 250 ohm headphones going that will match my build once I finish the cosmetics.


Well if you ordered early March then plan on an early/mid April shipment. My SpeedBall took just under 6 weeks to ship. That was during the NewYear time so it was busy for them. I was in no rush tho so it didn't bother me. Funny thing, I STILL haven't installed the SB! Just LOVING my stock Crack. I just wanted the SB on hand for the day I want to upgrade. What a great amp Doc at BH has designed. My hat goes off to that genius!!
 
Apr 3, 2017 at 9:42 AM Post #8,362 of 12,304
 
This is the style quarter inch stereo jack I will use in the crack, it should be nickel plated brass and once i remove the outer coating it should look good with the build. It is long enough to fit through an inch thick cabinet and made by Switchcraft, a quality brand.
  Check this list for where they're at in terms of shipping things out:
 
http://bottlehead.com/bottlehead-kit-delivery-status/


Yeah I have been checking the list and mine should take a little while yet. No biggy I have ordered some tools and parts that should take a while to get here. Once my cabinet is built i will have to decide on which of five or six finishing methods i want to use for quartered oak. I should be able to get it somewhat functional and then mount some parts in the box later. I have laid out entire television chassis and extended high voltage, convergence, and deflection so the thought of the components laid out before installation is not too scary. I will start on the top plate first and get the transformer and tubes mounted but that is all I intend to put there and that plate can sit on the old box for a bit. I will be adding a small transformer for my VU meters but everything will be well shielded. If I were to end up with hum, i will troubleshoot it. Before I do anything I have to fabricate the top, front and back plates. I want to do all cutting before I apply a patina to the copper. (sodium-chloride, nitrogen, and hydrogen). That process will take a couple days in itself.
 
Apr 4, 2017 at 11:34 AM Post #8,363 of 12,304
Hey all, I had a question about my stepped attenuator. I used it in my build and had no issues with it. However this weekend I rebuilt my Crack all the resistance values and voltages were good. Unfortunately when I tested the Crack with my headphones, when I turned the attenuator up 4 "steps" the right channels gets significantly louder and I can't hear the left channel. Steps "3" and "5" are both completely fine. Does this mean I somehow damaged my attenuator in the process or are there any steps I can take to test this before purchasing a new one?
 
Thanks all.
 
Apr 4, 2017 at 3:39 PM Post #8,364 of 12,304
Will the R1 resistor values on the speedball boards need to be adjusted if one would like to run a 6SN7? I'm running a Crackatwoa, but know that I need an adapter for the 6SN7, and that the R1 resistor positions on the small C4S board may need adjusting. I could try the tube, then adjust accordingly, but unsure if voltages will be too far off and harm anything without adjusting first.
 
Thank you,
 
-T
 
Apr 4, 2017 at 7:35 PM Post #8,366 of 12,304
  Hey all, I had a question about my stepped attenuator. I used it in my build and had no issues with it. However this weekend I rebuilt my Crack all the resistance values and voltages were good. Unfortunately when I tested the Crack with my headphones, when I turned the attenuator up 4 "steps" the right channels gets significantly louder and I can't hear the left channel. Steps "3" and "5" are both completely fine. Does this mean I somehow damaged my attenuator in the process or are there any steps I can take to test this before purchasing a new one?
 
Thanks all.
 

 
If only level 4 is  wrong, I would check for solder bridges, exposed wires causing a short,  and/or broken resistor leads. ( I'm assuming you have the ladder style with the resistors running around the outside. )
 
Apr 4, 2017 at 10:49 PM Post #8,368 of 12,304
   
If only level 4 is  wrong, I would check for solder bridges, exposed wires causing a short,  and/or broken resistor leads. ( I'm assuming you have the ladder style with the resistors running around the outside. )

 
Hey deserat, 
 
Yeah only the one step is wrong. It's actually step 3 though not 4. I took a look at the resistors and nothing seems broken, reflowed them just in case. There aren't any exposed leads or cables everything is trimmed as nice and neat as I could. I checked for solder bridges between steps 2 and 3 as well as steps 3 and 4 but everything looks good. Really unsure about what could be the cause of this since the pot was working perfectly before.
 
Is it safe to assume the problem is solely in the pot or is it possible that somewhere along the way something in the Crack circuitry is affecting this.
 
Apr 5, 2017 at 9:01 AM Post #8,370 of 12,304
If I read the specs correctly they are 20 ohm headphones...
 
Cack is output transformerless amp designed for higher impedance heeadpones like the Sennheiser, AKG, and Beyer designs.
 
20 ohms is not "higher impedance"....
 
Not a good choice for these headphones...IMO
 
Alex
 

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