Bottlehead Forum

Bottlehead Kits => S.E.X. Kit => Topic started by: DDDamian on July 17, 2015, 10:42:31 AM

Title: Sex on steroids - best way to increase usable range?
Post by: DDDamian on July 17, 2015, 10:42:31 AM

Hi all. I just upgraded my SEX 2.0 + C4S with the new 2.1 iron and some Mundorf Supreme caps. What a great upgrade to an already very special amp. I'm truly blown away by it.

In the last round of upgrades I wired the new transformers for 32ohms and also removed the 120ohm resistors from the headphone jack. I removed them to get a bit more ooomph from my LCD2.2's and HE-400's - both pretty current-hungry cans.

That sure did bump everything up, but I am finding a little higher noise and with my 300ohm Senn 650's and 800's the usable volume range is very small.

Which is the best way to go? Rewire the transformers to a lower output impedance, L-pad the jack or replace the 120ohm resistors?

Trying to find the happy halfway point.

Thanks in advance!

Title: Re: Sex on steroids - best way to increase usable range?
Post by: Paul Birkeland on July 17, 2015, 11:38:29 AM

Quote from: DDDamian on July 17, 2015, 10:42:31 AM

Which is the best way to go? Rewire the transformers to a lower output impedance, L-pad the jack or replace the 120ohm resistors?

The impedance switch kit will resolve the issue.  Switching to a lower impedance will give you a much lower noise floor, while switching to a higher impedance will give you more power (presuming that your load is still equal to or greater than the impedance tap selected).

You may also consider just leaving the amp on 4 Ohms, as there should be plenty of power available.

-PB

Modified by Josh to remove a confusing solution

Title: Re: Sex on steroids - best way to increase usable range?
Post by: JamieMcC on July 17, 2015, 11:44:07 AM

If you have not seen it  Mcandmars ramblings \ build thread has lots of info on modifying the Sex some are very inexpensive and simple to implement well worth a read through for anyone contemplating some Sex modifications.

http://bottlehead.com/smf/index.php?topic=5316.0

Title: Re: Sex on steroids - best way to increase usable range?
Post by: DDDamian on July 17, 2015, 03:01:30 PM

Thanks guys. I'm amazed how effortlessly it can feed either the high-impedance Senns or the current-hungry planars.

Not sure the questions answered though: either method reduces the power output, but is one method sonically better than the other?

Title: Re: Sex on steroids - best way to increase usable range?
Post by: Paul Birkeland on July 17, 2015, 04:02:18 PM

Quote from: DDDamian on July 17, 2015, 03:01:30 PM

Not sure the questions answered though: either method reduces the power output, but is one method sonically better than the other?

The lower impedance tap will be sonically better than an L-pad or the series resistors.

Title: Re: Sex on steroids - best way to increase usable range?
Post by: mcandmar on July 17, 2015, 04:22:15 PM

As above go for 4 or 8 ohms.  I find 8ohms works well with just about everything.

Title: Re: Sex on steroids - best way to increase usable range?
Post by: DDDamian on July 17, 2015, 04:39:17 PM

Brilliant guys - thanks for the help!