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the CTH (Compact Tube Hybrid) Rev A thread... - Page 3

post #31 of 596
Thread Starter 

Adding a wire going from the pot to IG worked! No more hum or buzz when touching the RK27 pot! Thanks again cfcubed!


I think I still heard a very very low buzz/hum with a few tubes though. It wasn't noticeable at all with other tubes. Tube heater voltage didn't matter. Some 12v had the buzz, others didn't. The 6v tube I tried out today was silent as well. Must be the particular tube then. Time to test all 15 or so tubes.

post #32 of 596

I will give up one of my CTH boards.  PM me only if you are going to build this amp in the next month or two. 


Of the 3, i am keeping one, sending one to ujamerstand and one more is going to someone who wants to build this one of these.  


Preference given to someone who hasn't built one of these before. PM me 

post #33 of 596

So, I recieved all my parts from Mouser/Digikey and am pretty excited to build the CTH Rev A.  Unfortunately, I am short one 9.31k resistor (my fault!).  Is there any chance a kind sole can purchase an extra when they place their order and put it in the snail mail for me?  Cheapest shipping from Mouser is $8, that is one expensive resistor :)  The part # is 71-RN55D-F-9.31K, PM if you can help out, I can paypal over the stamp and part cost.


Thanks in advance

post #34 of 596

Just order it in from digikey.

post #35 of 596

I'd say that it would be easy to find 1/8W resistors at a nearby electronics store - say Radioshack, but if you feel like waiting...I can include it in my upcoming order.


An alternative is to use resistors you have in parallel or series and get the resistance you want.  It would increase the power rating as well...

post #36 of 596

Bop- True but the heater circuit resistor values must be very close to their spe'd value & are tombstoned in a tight space. I've a spare 9,3k I offered to send if civilmonkey gets back to me before I leave on a trip (<< Ha ha, he just did this minute:).


Sachu -  You say just order from Digikey, do they ship for free or like $1 for a $1 part?

Edited by cfcubed - 3/23/11 at 3:57am
post #37 of 596

Cfcubed hooked me up.  Thanks everyone. Hopefully you will see a photo or two from me sooner than later.

post #38 of 596
Thread Starter 

Digi-Key has first class USPS shipping, which was like $2 for the 2 parts that are needed there as per the BOM. I'd imagine it would be the same for 1 resistor. It's better than the $6 or $8 that Mouser charges for ground shipping.

post #39 of 596

ahhhh. yes, that would work, but I don't think it's available to Canada.  My only option seems to be Fex-Ex overnight, although to be honest, I didn't complete the checkout process 100%, only to the shipping part.

post #40 of 596
Digikey is only FedEx to Canada at $8CDN flat rate.
post #41 of 596

Thanks to sachu I have a board on the way to me.  Actually he donated it when he learned that I'm building this up for my brother being deployed to Afghanistan.  Thanks, dude!  smily_headphones1.gif


My mouser and digikey orders are on the way with expedited shipping.  Hoping to tackle this one asap.


Maybe I missed it in the mega CTH threads, but where can I source some of that nice black perforated material for the top of the hammond case?




post #42 of 596

I'm told the perf top is standard perforated sheet metal.  I imagine you could find a local metal supply place and buy some.  The option I'm going with is drilling a symetrical hole pattern above each heat sinks and finshing them with black nylon grommets.

post #43 of 596

Boards are out on their way to Ujamerstand and BK, and one black perf top to mullet.

post #44 of 596

Missed the group buy :( Anyone has a spare board that you could sell me? Would appreciate a lot.

post #45 of 596

I purchased the following tubes for Project CTH-Kabul:


6CG7 RCA Clear Top

6DJ8 Amperex Bugle Boy Holland

6DJ8 Mullard Great Britain


Any others to consider to capture a broad spectrum?


I'm also assembling grub and skeleton DACs for the care package - I'll audition and include only one.  Any creative way to shoe-horn one of those babies into the short Hammond CTH case?  That would be super cool.




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