Sex it up with modding updates

[JamieMcC]

Cheers Bottlehead again!

Building the Sex has been a enjoyable and rewarding experience, no problems encountered the manual was nice and clear to follow even for me.

The Sex has proved just perfect for its intended use as a office/bedroom rig and sounds super with the Beyer T1's. I also could not resist hooking it up to my 25 year old Marantz bookself speakers which are a bit of a mismatch and could hardly believe my ears the 2.5W drives them to a decent level in the room and is easily the best I have ever heard them sound I was genuinely surprised and looking forward to trying out the Fostex FX120 drivers later with it once I get round to making a pair of enclosures for them.

Currently in stock form (save for the attenuator) and am looking forward to fitting the C4S and impedance switches a little later. I dare say a tweak or two some of those implemented by Mark (mcandmar) and Lachlan (Loquah) look interesting  But for now I am savouring a wee dram and enjoying the fruits of my labour.

Cheers guys

 

[wullymc]

Very nice work!

I love the look of the top plate!

Enjoy!....Dave

 

[mcandmar]

Very cool, congrats  8)

...i really should try some speakers on mine.

 

[JamieMcC]

The C4S doesn't take long to install and is pretty quick and easy compared to the Speedball in the Crack.

I have been pondering over output cap options and while I have a few to hand whilst going through them most have a lower voltage than the is required for the Sex, but I did find amongst them a pair of Jantzen Superior Z-Caps with a 800v rating, one of the very first caps I had tried bypassing with in the Crack and could not resist soldering them in.

I wasn't very fond of them in the Crack but they work a treat in the Sex  ;D

 

[mcandmar]

I knew you wouldn't be able to help yourself

Those two jelly bean .1uf interstage caps would be the first on my hit list, i believe they are actually Panasonic Polys.  There are plenty of Russian options to try in those sizes.  I confess to having bought a bunch of different types and never got around to trying them, the FT3's became a permanent fixture.

 

[JamieMcC]

Funny enough Mark I have some FT3's on the way 

 

[kgoss]

Nice work, I like what you did wth the top plate a lot!
I have Jupiter HT caps in my 2.0 version amp and liked them so much I never tried any others. I have them in both the interstage and output positions.  Jupiter now has a copper foil version that I am considering installing in the interstage position.  Sounds like a good  project for this winter.

Edited to change interstate to interstage. Dang auto complete on my iPhone!

 

[JamieMcC]

Thanks Ken,  I have been eyeing up the Audyn True Copper Foil recently and the Mundorf Supreme range always seem popular.

 

[Atraf]

Really nice man!
Which do you prefer? sex or crack?

 

[grausch]

If this sounds half as good as it looks, it should sound very good indeed.

 

[JamieMcC]

After following the discussion on Mark's (Mcandmars ramblings) thread a little while back on chasing down some noise experienced with some low Z cans I decided to implement a few of the modifications  discussed at the time by Mark, PJ, PB and the Doc. Whilst I find the Sex totally quiet with the 600ohm T1's and am really enjoying the Sex amp I am hoping these inexpensive modification will prove beneficially when running lower impedance headphones later on.

These are the ones implemented and the relevant discussion taken from Marks thread informative thread.

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

Part 2: Heater supply cap and resistor.

-Capacitor: As discussed further on in the thread doubling the capacity of the smoothing capacitor serves to half the ripple on the supply but has little to no audible or measurable effect on the noise levels of the amp. The capacitor i have used is a 22000uf Panasonic TS similar to the rest of the power supply caps, and physically the same size.

10000uf 10v - Lelon REA 85c 20% H010(M) 35mm x 18mm x 7.5mm - 2430mA
22000uf 16v - Panasonic TS-H 85c AECOS1CP223CA - 25mm x 35mm x 7.5mm - 6100ma 

- .1r Resistor: My hatred for those ugly wire wound cement blocks was my motivation here to source a Dale for no other reason than its not a cement block.  There are two versions of these being inductive and non-inductive, i opted for the non-inductive version.

- 100r Resistors: As suggested by PJ connecting two 100r resistors in series between the + and - terminals and grounding the center point serves to balance out the voltages on the DC side of the heater circuit.  This simple modification seems to have a considerable effect in reducing background hum and is highly recommend if you are having issues. Connect one 100r resistor between terminal C1 to C3, and C2 to C3 as shown in the attached pic.

 

[Strikkflypilot]

Looks really neat and tidy!
That single malt adds to the experience in a very good way, I take it?
Would be great to hear what You think the SEX is, compared to Your thoroughly upgraded
Crack.

 

[JamieMcC]

A Care package arrived today containing some Ampohm Paper-in-Wax Tin Foil and Ampohm paper-in-wax alum foil caps for the Sex ;D  I was very relived they turned out be smaller than I had imagined so as soon as I was home from work it was out with the soldering iron and in they went.

 

[HF9]

Nice! Some good old fashioned paper in wax!

 

[JamieMcC]

Nice! Some good old fashioned paper in wax!

These are my first paper and wax caps they took about 50hrs to burn in at first the mids where nice the bass was loose and muddy and there was something a bit strange about how the sound transitioned from the mids to highs. I had been leaving the amp running during the days on the speakers and came home from work and instantly noticed the amp sounded much more cohesive, bass had tightened up and was more focused and a lovely richness and density of tone has now appeared.

I added some Russian Teflon bypasses to the Ampohms last week I have a few more little tweaks to make but am enjoying listening to the amps so much I keep putting them off.

 

[JamieMcC]

Is there a cure for this madness? I found it to hard to resist the 20% off they had only on the Mundorf 2.7uf silver oils, which was odd as it made them less expensive than the 1.5uf's.  One of the nice things about buying stuff from German suppliers is they often include some sweets as a little gift a nice and touch   

 

[HF9]

Haribos, Bonus! ;D The Germans know their candy.

There is no cure for this sickness my friend, get used to it  8)

 

[JamieMcC]

Happy new year all.

Finally got round to replacing the resistors for two chokes to the Sex power supply today as detailed by Mark (mcandmar) in his "Mcandmars ramblings"  thread and it is a really nice modification the effect of which is instantly noticeable if anyone has been thinking about it.

 

[JamieMcC]

Something about my Sex has been really been bugging the hell out of me recently

 

So it was time to put that something right and proudly fix my Bottlehead badge in place on the front of the amp.  I am sure it sounds much better for it!

Thanks guys the Sex really is a very enjoyable amplifier it still regularly continues to surprise me with its ability and is also proving to be a superb match with the Fostex FX120 speakers

 

[JamieMcC]

Finally scratched the planar itch the HE-6 and the Sex is making for a enjoyable listen but I cant help but wonder what effect having a few more watts available might have....