Sonics, Crack vs. SEX

[tdogzthmn]

I am a happy Crack owner, but I would like to know how the SEX amp sounds in comparison to the Crack.  Are there any differences in overall sound or more in the details such as bass extension, texture, treble...  I plan to build one down the line and would like to learn how the two compare to one another.

Thanks.

[Paul Joppa]

Any chance you are close to the Seattle area? There's a HeadFi meet on March 5, both will be available - plus we are building a prototype of a third design which will hopefully be available for listening. It doesn't exist yet, so nobody's heard it, but could be interesting.  :^)

[Grainger49]

I can't tell you about the sound but the two Bottlehead headphone amplifiers are intended for different impedance headphones.  The Crack that you have is capable of driving "higher impedance" headphones, 100 ohms or higher.  That isn't to say that some users don't use low impedance headphones with it an still like the sound.  The differences will be in the control that the amp has on the bass most specifically.  The Crack is OTL and the headphone impedance works with the output capacitor to roll off the bass response.

The SEX amp has an output transformer that allows use with lower impedance headphones like the 32 ohm Grados.  The transformer allows for good bass response to such low impedances.  However it loses some control with the high impedance headphones.  But it also drives speakers, the Crack doesn't.

You can bet that there are more differences in the sound.  If you are not convenient to Seattle you might try in the General forum asking if there is a Bottlehead near who will share his equipment with you some afternoon.

[Lee Hankins]

I have both, each has been modified.  I always change out the RCA's and pot on any Bottlehead Kit, best sound improvement for the price.

Crack; PEC pot, CMC silver plated RCA's, silver/gold/teflon signal wire, teflon sockets with PCB adapter, and replaced coupling caps (bypass with teflon cap).  A photo is in the Gallery.

S.E.X.;  DAC pot, MagneQuest iron upgrade, auricaps.  No other upgrades because this kit was built in Seattle during Stem Cell transplant.

Headphones; Sennheiser HD 650 w/custom cable and AKG 701.

The Crack is just a wounderful sounding headphone amp, the SEX didn't come close with headphones, but excellent sound quality with my single driver speakers.  I had previously only used the SEX with headphones while in Seattle, nothing to compare with at the time.  It bothered me at the sound difference of these two amps, so I did a quick and dirty installation of bypass caps for the auricaps.  Without any break in the SEX became a new amp, much better than before but still not as good as the Crack, it will never be a good as the Crack (IMHO).  Just a side note, I never trust my ears when testing equipment, was assisted by my eldest daughter and her boyfriend.

One last statement, I have never heard a single bigger change in sound improvement than this addition of bypass caps in the SEX; .01 Vishay MKP 1837 on .1 Auricap and .1 russian teflon on 2.2uf Auricap.  The SEX is now a good headphone amp (great amp for speakers) but as stated above IMHO it can never be as good as the Crack, the Crack is just another magnificient Bottlehead product.

Cordially,
Lee Hankins

[tdogzthmn]

Any chance you are close to the Seattle area? There's a HeadFi meet on March 5, both will be available - plus we are building a prototype of a third design which will hopefully be available for listening. It doesn't exist yet, so nobody's heard it, but could be interesting.  :^)

I live in the SF Bay Area so I will be missing your Head-Fi meet.  Fortunately we are having our own Head-Fi meet and I will be there showing off my crack in its full glory.  Hopefully someone can bring a SEX amp to that meet for me to try.