S.E.X. 2.1 Retired!

[Doc B.]

The last S.E.X. kit sold early this morning. We have decided to retire the Single Ended eXperimenter's kit due to the supply of 6DN7s getting so sparse that we can no longer purchase the volume of tubes necessary to justify continued production. There will be plenty available in small quantities for some time if you need a spare. Thanks so much to everyone who purchased a S.E.X. kit in one (or more) of its iterations over the past 21 years. It's the kit that got us started, and we plan to continue cooking up unique and great sounding products like it for as long as I have new ideas - of which there continue to be plenty.

[Bonzo]

Looking forward to see the new masterpiece!!

S.E.X. is dead, long live the ______ !

[tdogzthmn]

Love my little SEX 2.1 it's been awesome as a headphone amp and diving my Orcas's.

I'd personally be interested in seeing Bottleheads take on an OTL power amp for speakers!  Love to hear some thoughts on this.

[Natural Sound]

Before I knew about Bottlehead I built a 6T9 amplifier that was featured in the August 2004 issue of Nuts and Volts magazine. At the time the 6T9 was plentiful and cheap. Fast forward to 2016 and the 6T9 is often difficult to find but if you do it comes with a hefty price tag. I still have that amp but I don't use it anymore. My S.E.X. 2.0 and 2.1 amps sound much better. I did learn my lesson though and amassed a small stock of 6DN7's that should get me to the end of the line.

http://www.sparetimegizmos.com/Hardware/Stereo_6t9.htm

[Doc B.]

Love my little SEX 2.1 it's been awesome as a headphone amp and diving my Orcas's.

I'd personally be interested in seeing Bottleheads take on an OTL power amp for speakers!  Love to hear some thoughts on this.

My thought is that it might be pretty cool if you had 600 ohm speakers. For 8 ohm speakers, what I would do would not be very practical.

[tdogzthmn]

My thought is that it might be pretty cool if you had 600 ohm speakers. For 8 ohm speakers, what I would do would not be very practical.

I've built and enjoyed the Crack a few years ago with my 600 ohm AKG's but I also know there are some manufacturers that make OTL Tube amps designed to work with speakers.  I can't comment about the efficiency differences between designs (OTL vs SET), I just know it has been done before.  Mostly I was wondering if it was something you had explored previously and abandoned? 

[Paul Joppa]

I have considered how to do that periodically, and always came back to the same point - it's just not practical without using a push-pull topology with lots of feedback.

Example: if the Crack works well into 600 ohms, then 75 paralleled cracks should work equally well into 8 ohms. But it's still a cathode follower, which means there is still some negative feedback sound. And it would consume 2 to 3 kilowatts, producing maybe 20 watts.

That's a crude analysis, and could probably be improved - but not dramatically.

[Jim R.]

I have always found it interesting that an awful lot of people with OTL speaker amps use impedance matching autoformers with their amps. If you have as warped a sense of humor as I do, you'll see the supreme irony in this :-).

[Brent]

Jim,

I have observed the same with some amusement. It's like the ingredients list on a slim Jim, which includes both 'defatted beef' and 'beef fat.'  It's just weird. But whatever floats your boat. I'm sure I do plenty of things other people think is pointless or wrong. 

Brent

[Paul Birkeland]

I have always found it interesting that an awful lot of people with OTL speaker amps use impedance matching autoformers with their amps. If you have as warped a sense of humor as I do, you'll see the supreme irony in this :-).

Yeah, god forbid that you tell that they no longer have an OTL amp, you'll cause a miniature meltdown on whatever forum you happen to be on.

[Jim R.]

Yeah, That's why I just shut. Up and let it be. :-)

As Brent said, I probably do plenty of things that other people think is odd.

-- Jim

[murray]

I have always found it interesting that an awful lot of people with OTL speaker amps use impedance matching autoformers with their amps. If you have as warped a sense of humor as I do, you'll see the supreme irony in this :-).

I think I see what you did there.  Yes, those big transformers would be very "irony". Lots of iron.

[murray]

I think the universe is trying to tell me something. I was slowly saving for the recently retired kit. It was to have been my first foray into tubes after years of transistors and MOSFETs.  Meanwhile, in the weekend, my old oscilloscope has died (fried) for what looks like the last and final time, so my first job will be to look around for a new one, as there's several projects on hold now.
I'll still keep an eye out here, though.

[Jim R.]

Hi Murray,

Yes, the universe is telling you to get one of the other kits ASAP -- you won't need the scope to build one. Of course, I have no idea what else is on your bench, so maybe the scope is more important to you right now.

Good luck with whatever path you take.

Take care,

Jim

[Wardsweb]

This will always be one of my favorite little amps.

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fwww.wardsweb.org%2Faudio%2Fsexamp%2Fsexamptop.jpg&hash=64085df9efabdce9f65ad70b113db79e95a457d9)