Revitalizing SEX with C4S - resistor question

kyelenik · 1195

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Offline kyelenik

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on: December 30, 2013, 12:01:31 PM
Apologies in advance for this newbie question.

It's been 7+ years since did my last bottlehead project (2006).  I purchased and built my SEX kit and have been loving it's use as a headphone amp.  For various tragic (or maybe lucky) reasons, I am now using it as well to drive my speakers.  It sounds very nice, but I now hear where it could use the C4S - which I purchased with the kit but never installed. 

Does anybody have a nice and easy way to determine the C4S resistor values? 
I have started reading the directions, but these days I do not have enough knowledge or time to tackle the methods described.  Searching the net for hours is no longer in the card either (although that sounds nice). 
I am ready to tinker but need the cliff's notes! 

If it matters to the sizing, these are the other components:
Seduction/Anticipation C4S phono pre
Foreplay modified with C4S, Goldpoint stepped volume control, -20dB T-padded input
SEX (no mods)
Meadowlark Kestral Hod Rods (89dB, 6.5Ohm) 

Thank you in advance for help!



Offline Paul Joppa

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Reply #1 on: December 30, 2013, 02:35:23 PM
If you mean, what are the values of the resistors included in the kit, use your meter to measure them. That's what I do with every resistor before actually installing it.

If you mean what SHOULD the values be, they are identified in the parts list.

Paul Joppa


Offline Doc B.

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Reply #2 on: December 30, 2013, 03:23:02 PM
For the SEX 2.0 R1 is 499 ohms, R2 is 150k ohms. Remove the 150k plate loads, c4s boards go in their place. Also change 8.2k ohm power supply dropping resistors to 18k ohms.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline kyelenik

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Reply #3 on: December 30, 2013, 11:55:20 PM
I should have clarified that there were no resistors included in the C4S addition purchased with my SEX - just the boards, transistors, and LEDs. 

I will try with the values provided in the quick reply - thank you. 

One more question: Was my SEX (June 2006) version 2.0? 

Thanks again to Doc B, Paul and crew...Happy 2014 to you.



Offline Doc B.

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Reply #4 on: December 31, 2013, 08:40:48 AM
Yes, 2.0. The 150k resistors should be rated for about 2W.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.