Here's proof that S.E.X. never goes out of fashion. PJ and I spent the last couple days building this first prototype of the newest version of the Single Ended eXperimenter's amp. The original S.E.X. amp went out of production a few years ago, but I felt the concept was more valid than ever, as more and more folks are considering reasonably priced ways of getting into tube audio. I also felt that we could use our 10 year experience base to develop and offer a far more versatile product than one finds in other tube audio kits. And so we put this S.E.X. for the 21st century project ahead of everything else.The new integrated stereo single ended parafeed S.E.X. amp uses 6DN7 dual triode tubes like the original, but only one per channel rather than the original parallel pair, for improved clarity and resolution. One can use 6EM7s as well with a little reworking of the circuit, along with a whole slough of other tubes if one wants to get into the Frankenstein school of homebrew amp/preamp/headphone amp design. Output transformers are the same as used in the stock Paramour, but they are wired as autoformers in this design. PJ spec'd dual bobbin plate chokes have 30H inductance (mounted under the chassis), and performance is about 2wpc into 4 or 8 ohms (using the corresponding tap), 30Hz-30kHz. The single power transformer sports two separate high voltage windings, so there are actually dual mono B+ supplies. The input stage is biased with 431 precision voltage reference chips.
Like the Paramour, the speaker outs (which are on the back with the RCA inputs and the IEC power cord socket) can be wired for 8 ohms or 4 ohms, and as you can see we are experimenting with setting the circuit up so that the integrated amp can optionally be used as a headphone amp via a Neutrik 1/4" stereo jack wired with the IHF standard 120 ohm series resistance. And you could even make up a stereo 1/4" plug to dual RCA jacks adapter and use the SEX amp as a preamp if you were really hungry for an inexpensive autoformer output preamp. An adventurous type seeking more power on a budget could even try rewiring the circuit into a push-pull monoblock. Like I said, it's all about versatility.
We still have some refinements to make, and we are not quite ready for orders yet, but the project is progressing well. Price is hoped to come in around $299.
Follow Ups:
- Nice going Doc!! What's the approx output? (nt) - JP 13:06:42 04/30/04
(2)
- In Reply to: sneak preview - SEX! posted by Doc B. on April 29, 2004 at 18:22:01:
.
- Re: Nice going Doc!! What's the approx output? (nt) - Doc B. 14:10:12 04/30/04
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- In Reply to: Nice going Doc!! What's the approx output? (nt) posted by JP on April 30, 2004 at 13:06:42:
Hasn't changed since I posted it last night ;^)> - about 2, maybe 2.5 watts per channel.
- Thanks Doc, I gotta get those wipers reinstalled on my glasses ;-) (nt) - JP 04:44:25 05/01/04
(0)
- In Reply to: Re: Nice going Doc!! What's the approx output? (nt) posted by Doc B. on April 30, 2004 at 14:10:12:
.
- Thanks Doc, I gotta get those wipers reinstalled on my glasses ;-) (nt) - JP 04:44:25 05/01/04
(0)
- Re: Nice going Doc!! What's the approx output? (nt) - Doc B. 14:10:12 04/30/04
(1)
- Very cool - GLF 08:49:04 04/30/04
(2)
- In Reply to: sneak preview - SEX! posted by Doc B. on April 29, 2004 at 18:22:01:
Will this amp work with the upgraded paramour output transformers?
Have you given it a listen with those Senns?
Andrew
- Re: Very cool - Doc B. 09:37:43 04/30/04
(1)
- In Reply to: Very cool posted by GLF on April 30, 2004 at 08:49:04:
The amp is set up to use the stock Paramour output transformers as 8K loads. The Paramour upgrade transformers are 4k only and they are bigger, so they won't work all that well in this different application. The intended use of this kit is mostly to give folks an easy to build and very versatile first taste of tube audio in the form of a compact amp that can be the heart of small systems like dorm room stereos and computer sound setups. The headphone option was one of those palmprint on the forehead things - "this amp is perfect for a headphone setup, why didn't we think of it years ago?" - and so far the results seem very satisfying with the HD600s and several other headphones. Using the IHF standard setup of a 120 ohm resistor in series with the transformer secondaries is cool because it does a great job of leveling the output regardless of the headphone impedance and it also helps to lower the noise floor even more, which is useful for headphones. We haven't had a chance to check the frequency response of the headphone output, and I still have a few other things to try, but the initial impression is very positive.
S.E.X. has been reintroduced because I wanted to create a three tier product line structure. At around $300 for an integrated SE amp kit it will be our lowest priced means of getting a "full" tube audio setup that requires only a source and speakers. Because of the price point we can't spend a lot of R&D time developing upgrade kits. But because of the design's basic quality and versatility many folks will certainly come up with their own upgrades. It would be difficult for us to support all of the cool ways you could tweak the circuit. Shoot, just off the top of my head I can think of converting it into a preamp with a FP-like circuit with buttkicking cathode follower output, a stereo single gain stage amp with 6C45pis, or a class AB2 PP amp of maybe 8-10 watts output. You could use it as an input/driver stage for a bigass 211 or 805 SE booster amp output stage, by cap coupling off the of the OT primary. The possibilities are abundant.
I envision the Wiki we are setting up as a place for folks to share their mod ideas so that the community itself can do the experimenting and sharing of the results.
We will continue to recommend the Foreplay/Paramour separates path as a way to start modestly and upgrade to a high end system without having to learn a lot of electronics - a mid range of kit tweaking madness, if you will.
And we will eventually get the Paradox and a more evolved preamp out as our top range products, which will have all the trick stuff we can come up with included right from the start.
For this particular case you might want to talk to Mikey about getting some custom EXO-010 10K primary parafeed transformers and matching plate chokes made. Those might really kick butt in this amp.
- Re: Very cool - GLF 12:52:07 04/30/04
(0)
- In Reply to: Re: Very cool posted by Doc B. on April 30, 2004 at 09:37:43:
Thanks for the responce Doc.
I have been looking for something to serve as a headphone amp and something to drive some small, efficient speakers (maybe the oneZ from ACG) for the computer. This looks like the ticket.
Andrew
- Re: Very cool - GLF 12:52:07 04/30/04
(0)
- Re: Very cool - Doc B. 09:37:43 04/30/04
(1)
- If you were not around then, a pic of the Original S.E.X. - Wardsweb 07:15:59 04/30/04
(0)
- In Reply to: sneak preview - SEX! posted by Doc B. on April 29, 2004 at 18:22:01:
The Original S.E.X.
- Dude, - tcain 07:02:12 04/30/04
(0)
- In Reply to: sneak preview - SEX! posted by Doc B. on April 29, 2004 at 18:22:01:
Like if hi-fi wasn't twisted enough. And now this. Please send ^some^.
That is a breakthrough. Well done guys.
TC
- Finally time to build that tubed 5.1 system - Mudhiker 21:48:45 04/29/04
(0)
- In Reply to: sneak preview - SEX! posted by Doc B. on April 29, 2004 at 18:22:01:
Yea! Something else to warm the iron for now that I've finished (for now) the foreplay and don't yet have the cash to spring for the bix/seduction combo... This'll make a nice kitchen amp which'll later drive the rear channels of my home theatre...maybe another of these to handle the center channel and sub...connected to a plate amp sub of course...if I ever get a television!
- S.E.X. from behind - Doc B. 18:25:51 04/29/04
(22)
- In Reply to: sneak preview - SEX! posted by Doc B. on April 29, 2004 at 18:22:01:
Here's the back side of the integrated SEX amp showing the input jacks, stereo speaker outs, and the IEC socket. Chassis plate is 8" x 10" and overall size is about 9.5" x 11.5" by about 6" tall. Should fit easily next to your computer, and plug right into that cool soundcard you bought...
- re: and plug right into that cool soundcard you bought... - artsybrute 15:45:23 04/30/04
(0)
- In Reply to: S.E.X. from behind posted by Doc B. on April 29, 2004 at 18:25:51:
So cool!
I was wondering why you posted that internet radio site.
Now I'll be able to use my KLH model 17's! And probably my Alps black beauty. And ...
Truthfully, I was just talking to JP about wanting an integrated tube amp for the PC.
Tres tres cool.
- Oh baby! Sign me up! - John Bennitt 19:40:17 04/29/04
(2)
- In Reply to: S.E.X. from behind posted by Doc B. on April 29, 2004 at 18:25:51:
I know the original schematic has been out in VALVE for a few years, but can you say "Anticipation"?
How soon can we expect these to be ready to order?JB
(listening to Django over FP/PM's and in need of a kitchen system)
- Re: Oh baby! Sign me up! - Doc B. 20:17:34 04/29/04
(1)
- In Reply to: Oh baby! Sign me up! posted by John Bennitt on April 29, 2004 at 19:40:17:
This is a different circuit than the original S.E.X. design. In the original we used two 6DN7s with the output triodes wired in parallel and the input triodes wired as a mu follower, on a monoblock chassis. You got more power with that design in it's final parafeed iteration, but the sound was a little less refined because of the parallel tubes. In this iteration I wanted to come up with something more compact, hence it became a stereo amp that used one tube per channel that doesn't require a separate control stage. With PJ's superior understanding of the tradeoffs of operating points and our much broader access to parts that can really fine tune the circuit these days, this S.E.X. amp is a fairly evolutionary step from the original.
We have a few ideas we want to work on before we call the design done. Once we feel it's ready (I suspect this will happen in the next couple of weeks) it should be four or five weeks before we have all the parts on hand to build and photograph the production prototype for the assembly manual.
- Whoo whee! (nt) - John Bennitt 20:25:26 04/29/04
(0)
- In Reply to: Re: Oh baby! Sign me up! posted by Doc B. on April 29, 2004 at 20:17:34:
This heat is killin' me!
- Whoo whee! (nt) - John Bennitt 20:25:26 04/29/04
(0)
- Re: Oh baby! Sign me up! - Doc B. 20:17:34 04/29/04
(1)
- Re: S.E.X. from behind - Binayak Bhattacharyya 19:38:39 04/29/04
(0)
- In Reply to: S.E.X. from behind posted by Doc B. on April 29, 2004 at 18:25:51:
Now after all the Foreplay at home I can have S.E.X. at work. Way cool!
Bin
- Re: S.E.X. from behind - Matt in Dayton 19:23:47 04/29/04
(14)
- In Reply to: S.E.X. from behind posted by Doc B. on April 29, 2004 at 18:25:51:
Why the language. I find it offensive,very poor taste. Immature.
Matt Reddington
- Re: S.E.X. from behind - Grainger49 08:05:37 04/30/04
(1)
- In Reply to: Re: S.E.X. from behind posted by Matt in Dayton on April 29, 2004 at 19:23:47:
Ok, I have waited and considered all that has been written to this point. I don’t agree with Matt, but this country is founded on the belief that he has a God given right to say whatever he believes.
An old phrase I have used is, “if everyone is thinking the same, someone is not thinking!” And that is the TRUTH. We need differing opinions everywhere. That and the tolerance for differing opinions is one of the things that makes, “everyone want to come to America.” I was told this by a Chinese engineer I worked with. And I have come to believe him.
So, the names may not be for everyone. Matt may not like them. We don’t know his deepest reasoning, we could agree if we knew, but it isn’t up to him to divulge that. So we can be happy agreeing to disagree. It doesn’t keep us from being friends.
Grainger Morrison
There Is Only One
- Well said - Steve Culton 08:16:08 04/30/04
(0)
- In Reply to: Re: S.E.X. from behind posted by Grainger49 on April 30, 2004 at 08:05:37:
I agree completely. My little joke post below was intended to be good-natured. I don't happen to agree with Matt, but he cerainly has a right to his opinions.
One thing I love about the Bottlehead forum is the complete lack of bad attitudes and macho-shithead flaming. I'm always in awe of how Doc deflects confrontational bad mojo posts. He certainly has more grace and patience than I do.
;-)
- Well said - Steve Culton 08:16:08 04/30/04
(0)
- um, think FCC and Bono... - pRC 19:51:56 04/29/04
(4)
- In Reply to: Re: S.E.X. from behind posted by Matt in Dayton on April 29, 2004 at 19:23:47:
He's (OK, could be she) is from the UK. Discussing a product with this name, not sure he's over the line or outside the limits of eccentricity. Flame me if you want for contradicting you, but maybe BR is just excited. I'm just not sure an off-color comment is not a sign of the decline and fall of civilization.
Nice looking amp, Doc. Looks like a good kit for lots or projects! Might wanna make those binding posts symmetrical - if the GND posts were both facing together it might reduce the chance of a clumsy short?
/pRC
- Re: um, think FCC and Bono... - UK Ray 04:05:55 05/02/04
(2)
- In Reply to: um, think FCC and Bono... posted by pRC on April 29, 2004 at 19:51:56:
Is the fact that he's from the UK relevant?
Ray
- Re: um, think FCC and Bono... - pRC 05:15:32 05/02/04
(1)
- In Reply to: Re: um, think FCC and Bono... posted by UK Ray on May 02, 2004 at 04:05:55:
OK, maybe a stretch there... it has been a couple of years since I was last over on business. I do know that there are all sorts of people over there, but 'fucking brilliant' is not an expression that rolls off the tongue here in the US. Too much exposure to the Osbornes I suppose?
Apologies if I have offended, I was only dashing off a reply without thinking.
Go UK!
/pRC
- Two Peoples Seperated by a Common Language - UK Ray 10:59:17 05/02/04
(0)
- In Reply to: Re: um, think FCC and Bono... posted by pRC on May 02, 2004 at 05:15:32:
No offence taken, just didn't want you thinking that we have all had lobotomies, which brings the topic back to the Osbournes.
Actually, it would appear to one that the SEX looks rather promising and shelling out some dosh for one could be a good crack.
Cheers
Ray
BTW. Bono might take offence at you suggesting that he's from the UK as he hails from Ireland, which isn't part of the UK - that's assuming that I have the right Bono, he of U2?
- Two Peoples Seperated by a Common Language - UK Ray 10:59:17 05/02/04
(0)
- Re: um, think FCC and Bono... - pRC 05:15:32 05/02/04
(1)
- Re: um, think FCC and Bono... - Doc B. 20:01:50 04/29/04
(0)
- In Reply to: um, think FCC and Bono... posted by pRC on April 29, 2004 at 19:51:56:
Good idea Randy. We laid things out facing the same way as much as possible for both channels. If you look at the OTs you can see that they both face the same way. The underchassis wiring is thus pretty much identical from channel to channel, hopefully reducing any wiring errors induced by the dreaded mirror image syndrome. But it would be pretty simple to rearrange the binding posts, and it might well help to avoid shorting + to -.
- Re: um, think FCC and Bono... - UK Ray 04:05:55 05/02/04
(2)
- Re: S.E.X. from behind - Pete B. 19:50:57 04/29/04
(4)
- In Reply to: Re: S.E.X. from behind posted by Matt in Dayton on April 29, 2004 at 19:23:47:
Matt,
The original S.E.X. amps were so-named as Single-Ended Experimentation - yeah, it's silly, but harmless silliness. Then the preamp, which comes before S.E.X., was named Foreplay. If you upgraded your S.E.X. (like I did) to 2A3 output tubes, Magnequest output transformers, and a new circuit, it was renamed Afterglow (after S.E.X., get it?!?!?) The list goes on, with variations to add references to parafeed - the parafeed version of the Afterglow was the Paraglow, then the entry-level 2A3 amp was the Paramour (another romance reference, geddit?), and the phono preamp is Seduction (before Foreplay). I won't further offend you with my theory on the Straight 8 speakers (though someone will probably make some bogus reference to old car engines - before V-8s).
All in good fun, but it might hurt sales in some circles, I guess. Doc, done any market research on that point?
Regards,
Pete Boser
- probably a good thing... - mrh (Mark Hardy) 08:51:04 04/30/04
(0)
- In Reply to: Re: S.E.X. from behind posted by Pete B. on April 29, 2004 at 19:50:57:
... that the good Dr. and Company have refrained from offering full-range loudspeakers using 6" x 9" drivers, then...
all the best,
mrh
- Re: S.E.X. from behind - Doc B. 20:36:37 04/29/04
(2)
- In Reply to: Re: S.E.X. from behind posted by Pete B. on April 29, 2004 at 19:50:57:
Hi Pete,
Thanks for the cool historical explanation. Matt has spoken with Eileen in the past and expressed his concern over our product names, so I'm guessing that he is aware of the names of the other products as well. Matt is certainly entitled to his opinion. He is also responsible for creating whatever image he wishes others to envision of him through the content of his internet posts, as we all are.
I can think of two other individuals who have expressed offense regarding our products in the past. One was a member of the clergy. I've been offended by the marketing style of members of the clergy a few times, so I called that one a wash. The other fellow found a cute picture of my two year old daughter with 1/2" her butt crack showing over the top of her pants offensive enough to send me a rather insulting letter along with his renewal to the then still in print VALVE. I sent his money back. There was someone who was unhappy with the picture of Eileen moving the Straight 8 too, but I don't recall the details. I think that was one of those "my wife was offended" e-mails. She was apparently not offended enough to send an e-mail herself.
Everyone has different levels of tolerance and different matters over which they become offended. I've always found sex (the kind without the punctuation) to be alternately beautiful and hysterically funny. I can't say that I can relate to it being offensive. Well, there was that one date many years ago, but I digress.
My impression has been that the original marketing strategy worked well, that is, folks remember the names of our products. Do a google for the word Foreplay. A link to our kit's webpage comes up in the first 10 of 541,000 results. So I'll guess the "marketing research" is paying off.
- No offense here - Steve Culton 06:54:18 04/30/04
(0)
- In Reply to: Re: S.E.X. from behind posted by Doc B. on April 29, 2004 at 20:36:37:
I am not offended. My wife is not offended. Then again, we tend towards the naughty end of the spectrum. ;-)
Seriously...life's too short, y'know?
- Re: offended wives..... - Matts 20:45:50 04/29/04
(0)
- In Reply to: Re: S.E.X. from behind posted by Doc B. on April 29, 2004 at 20:36:37:
Once I worked at a firm where there was an associate retreat every year and spouses (primarily wives) were not invited to attend. There was a group of them who were very mad about it- and their husbands complained very loudly about it. Finally the firm put it up for a vote by the associates to see if we wanted spouses to attend. About 10 guys stood up and spoke in favor of inviting spouses- in impassioned voices. Then a secret ballot was taken, and there was only ONE vote in favor of it out of about 100 people voting....
Looks like a cool new project...
- No offense here - Steve Culton 06:54:18 04/30/04
(0)
- probably a good thing... - mrh (Mark Hardy) 08:51:04 04/30/04
(0)
- S.E.X. from the side - newsjeff 19:49:25 04/29/04
(1)
- In Reply to: Re: S.E.X. from behind posted by Matt in Dayton on April 29, 2004 at 19:23:47:
This post is twofold. I wanted to see more pics of the S.E.X. project. And I wanted to piss Matt from Dayton off some more. Loosen up, Roddington.
- LOL! He(a)r, He(a)r! - John Bennitt 19:56:49 04/29/04
(0)
- In Reply to: S.E.X. from the side posted by newsjeff on April 29, 2004 at 19:49:25:
OK - no more martini's for me. Still chuckling - "Roddington", ouch!
Mo' pictures please!
JB
- LOL! He(a)r, He(a)r! - John Bennitt 19:56:49 04/29/04
(0)
- Re: S.E.X. from behind - Grainger49 08:05:37 04/30/04
(1)
- Re: S.E.X. from behind - BR 18:59:00 04/29/04
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- In Reply to: S.E.X. from behind posted by Doc B. on April 29, 2004 at 18:25:51:
Thats fucking clean, headphone amp her I come!
- Re: Thats cool!(nt) - Spaaaz 18:42:11 04/29/04
(0)
- In Reply to: S.E.X. from behind posted by Doc B. on April 29, 2004 at 18:25:51:
.
- re: and plug right into that cool soundcard you bought... - artsybrute 15:45:23 04/30/04
(0)
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