Just finished my S.E.X. 3.0

[ejb14]

And wow - what a difference over the stock headphone amps in my solid state preamps. Really enjoying this!

This question has probably been answered already, but where would I buy replacement tubes? 6FJ7's - sorry, new to tube amps in general and just want to make sure I get quality replacements. I would like to buy a couple of sets to ensure I have some on hand in case one gets blown or wears out. Also, I noticed the two that came with the kit are not the same brand (GE and RCA) - I take it they don't need to match?

Thanks!

(added some pics - came out real nice, thanks to terrific instructions!)

[Paul Birkeland]

Most tube dealers should have some 6FJ7s laying around, though they may not list them.  There also should be some available on eBay (do not buy or pay attention to the prices from Bangy Bang Tubes). 

The printing on the tube is just a label, do the internals of the tubes match?

[ejb14]

I think they match yes - just looked at some pictures I took on my phone and they appear to have the same insides..I will take a closer look when I get back home after work today.

Thanks for the tip on Ebay! "Most tube dealers" - do you have any specific sources you could recommend - perhaps where you got the ones from my kit I am finding a few online like tubedepot (out of stock) and the tube store (just says 'assorted brands in stock'). I am just hoping to get a tube that is either new/old stock and unused or at least guaranteed to be up to specification. I don't want to put in something that will hurt this beautiful amp.
Thanks again!

[Paul Birkeland]

You are going to find that most 6FJ7s available are nos.  I would order from vacuumtubesinc.com.

[ejb14]

Excellent thanks - and thanks again for the Bangy Bang tubes warning - they have lots of 6FJ7's available and 100% positive reviews on Ebay. I would have definitely ordered from them otherwise.

Thanks for the tip on vacuumtubesinc.com too - I will buy from them.

[ejb14]

Sorry for all the questions - is there an Frequently Asked Questions thread for the S.E.X. kit?

For instance, I understand that the lifespan of the tube may be circuit dependent, so was wondering how long I should expect the S.E.X. kit tubes to last. I see a general 500 to 1000 hours for tubes in general.

Thanks again for all your help!

[Tom-s]

I wouldn't be surprised for a tube to survive 10.000-100.000 hours in a good circuit.
Don't worry about it. It will take you a few years of continues amp-on time to get them to run out.

In some manufacturers data sheet for long life tubes (at least >10.000 hours), they do make a statement that this is under condition's where a tube doesn't get more than 12x on/off every 24 hours. So switching an amp on and off a lot might influence tube life.

[Paul Birkeland]

For instance, I understand that the lifespan of the tube may be circuit dependent, so was wondering how long I should expect the S.E.X. kit tubes to last. I see a general 500 to 1000 hours for tubes in general.

I have a similar amp running in my shop with a slightly different (but very similar) Compactron tube.  I think I got about 5 years of constant operation before they started sounding funky, which is about 40,000 hours.

[ejb14]

Great - thanks again for all your help! Much appreciated!
-Ed

[Karl5150]

Nice, clean build. Enjoy the S.E.X. There is something magical about these little amps.

[skatole1967]

I am glad you started this thread!  I just finished my S.E.X. as well.  I am really happy with how it sounds.  I have heard heard a few  Schitt and Audio Gd amps in this price range but I have to say that even the stock SEX amp punches well above its weight.   I have the C4S upgrade parts sitting on the table and I'm wondering how it will improve on the great sound I already am getting.  I have tried the SEX so far with Focal Clears, Audeze LCD 2.2s, Audeze isine 20's, and some Massdrop Fostex TR-X00s.   I felt like the LCD 2.2s and Massdrop cans sounded great.  The LCD 2.2 is pretty inefficient though.  It's a good thing the SEX has so much power on tap.  The isine 20 didn't fare so well.  Too much midrange emphasis with a very metalic sound.  The Focal?  All I can say is wow.  They just sound so meaty, so clean throughout the audible frequency spectrum.  I have heard the Focals thru the Woo Audio WA22 and the sound is very similar to me with the SEX.  Not bad considering the Woo is about $2500. 

[Karl5150]

Looks great, the chokes and transformer in gold work well with the black plate. Sounds ( :p ) like you have the HP bases covered. And with what the S.E.X. amp can do with the right speakers it is an even bigger bang for the buck. 

[skatole1967]

Thanks Karl.  I will probably just keep the SEX as a headphone amp.  Unfortunately, my speakers aren't very efficient, Magnepan 1.7s (around 86 dB), so I haven't even bothered to try them with the SEX.   .  I think eventually I will try to build a Kaiju 300B amp and mate that with a more efficient speaker. 

[Paul Birkeland]

A pair of strapped Kaijus might just get you there!

[skatole1967]

That sounds like a good plan, Paul!   I have always wanted a 300b amp, the Kaiju may be just the ticket.  I just completed the C4S upgrade with the SEX.  I noticed when I did the voltage checks afterwards that there was a discrepancy between the OA and OB values.  I got 48 V for OA and 72 V for OB.  Is this a wiring issue, transistor issue or is this just normal tube to tube voltage variations?  All four LEDs light up.  As far as the SQ, it is fabulous.  IMHO, it sounds even better than stock with a more refined presentation.  More resolution, images are more distinct, bass is tighter and better defined.  All in all, I am very pleased with the upgrade and overall performance.