Ceriatone Forum

Hi guys

I am looking at building an amp soon. I will most probably do a 5e3 circuit as I really like the simplicity of the circuit.

Now my problem comes when I need more power than 2 6v6 tubes are going to give me. I know the 5x3 uses 6l6 tubes with but these aren't really the sound I am after. I would rather use kt66s or possibly el34s.

Would this be similar to the 5x3 design for 6l6s? What further mods would I need to make to the circuit?

This would get in the realm of about 20w yea?
I am looking to between 20 - 30w. Would I be better off taking the power amp section of a higher powered amp and the front end of the 5e3 to build something more to my suiting or will there be problems here as well?

Are there any other simple designs that I could look into? I like the least amount of knobs possible...

Thanks for any help you can give me. Sorry for the long windedness of my post but I hope it all makes sense.

Cheers

Adam

I guess I would start with the KT66, they should drop in with a bias check. The EL34 will need some finagling of the power tube socket, screen resistors etc. Not a huge deal, but it seems like the 66 would be the easiest place to start....
I am assuming Ceriatones PT can handle the current demands of the new power tubes. I believe Nik uses the same PT for the X3 model, so you should be OK.
Good Luck

The 5X3 uses the the same transformers as the 5E5 Pro.  Higher voltage power transformer and beefier, higher--wattage output transformer.

There are two things required to really get extra output from the larger power tubes.  Higher plate voltages and a higher output output transformer.  You can boost the voltages by swapping rectifiers to a 5AR4 or SS rectifier (heck, you would need to anyway for it to bias right), but the small-ish 5E3 output transformer will choke off any significant increase in output.  Tube amps are rather reactive.  If the output transformers can only handle 15-watts RMS, that power tubes will only put out 15 watts, no matter how hard you try and push them (unless you push them to damage)


That is EXACTLY what a 5X3 is. 

The 5X3 is a 5E3 front end married to a 5E5 back end that is cathode biased.  The 5E5-A Pro Ceriatone offers is fixed-biased and around 35-40 watts.  The cathode-biased 5X3 is probably around 25-30 watts.  (the 1955 5E5 was cathode-biased, the 1956 and later 5E5-A was fixed biased).

I like Wyatt's post here. it is very well done and is accurate with regard to tube amp theory. 

One thing that I found by a happy accident is that many modern build guitar amps use plate voltages that are above or at the maximum ratings for the power tubes.  A few amp builders are using power transformers that offer lower secondary (high voltage tap) voltages than what the majority use.   This is in regard to 6v6's and 6l6's.   There is a wonderfully different tone palette available by doing this.

I found this out purely by accident from purchasing a wonderful sounding amp through eBay, a Siegmund Midnight Blues (Blues Breaker) head.  It is offered from the builder tube rectified, also supplied with a proprietary SS rec adapter in three different voltage ratings for the main power transformer and also a choice of at least three different styles of output transformer in style of windings and capacity for current.  Mine was built with the lowest voltage PT option and has the larger, but not largest sized Radiospares type OT.  This type of OT was only used in the very few first Marshall amps due to its excessive cost.  Even when using only a pair of 6f6g's, the amp is surprisingly loud, and wonderful sounding. 

Being a vintage tube collector with literally hundreds of vintage preamp and power tubes in my stash, I found that I was able to run the older versions of 6v6 and particularly 6l6 power tubes, and the tones I got from doing that were jaw droppingly gorgeous.  Since the amp uses a fixed bias pot and bias balance pot in it's build, I was able to try tubes ranging in output from 6f6g all the way to 6550 in power tubes, and the output sockets had pins 1 and 8 connected to run el34's and kt66's as well.

My point here is that if a lower voltage PT is used, then the user gets to try the earlier versions of 6l6.  There is an increase in power over 6v6, but not as much as the jump in output to the later build 6l6gc types available today, and frankly the old glass just sounds better, in some cases MUCH better.  Currently I'm running a Bendix Red Bank 5r4 "tater masher" in the rec socket, and a pair of British vintage Emitron (Genelex type) kt66's in the power tube sockets, and the tones are beano-ish to say the least. 

So if this 5x3 were built with a PT having say, 275- 300v secondary taps and in sufficient current capacity, with all other things considered the use of these older 6l6 types, particularly the real 5881's, (Sovteks excluded) 6l6wgb mil stock, or 6l6gb's  should result in a wonderful sounding build.  Output will fall within the range that the OP wanted.  Old style tubes for an old style amp platform!  These older tubes are available on eBay for less than horribly expensive prices, and even though you might have to get  more than just a pair within a chosen type to put together a nicely balanced pair, the results are very much worth the effort.  And of course with pins 1 and 8 connected on the power tube sockets, this platform should be able to run kt66's or el34's as long as sufficient heater current is available from the PT.   Perhaps a few component values in the power section could be tweaked to optimize the circuit for el34's.