6V6 - Best Distortion Ever ?

[kepeb]

sounds like fun. maybe i could have a go at starting one of these on sunday.

I have been reading CJ and others used various power transformers as cheap output iron.
this would need to be single ended/gapped right?
I still have an old ptx that would suit this and most of the other parts laying around somewhere.
is there a budget/hack output tx? or what am i looking for there?

 

[MasonAtom]

Pretty amazing how much opinions on guitar amps can differ from person to person. I rarely design for predominantly power amp distortion. It never has the edge that I like. To my tastes, I find the best sounds come with the right balance between preamp and poweramp distortion. As they say, your mileage may vary...

And I absolutely hate tone stack defeat mods in any amp I've ever played or built. Recipe for mud IMO. The only 'single knob' EQ I like is the Tilt control (Big Muff Pi, etc), and even that I find extremely limiting.

I've never been super impressed with 6V6 or EL84. 6V6 is ok, but I don't like EL84s at all. For me, KT66 and KT77 is where it's at. I prefer 6AQ5 over 6V6, although maybe that's because you typically run them at a lower voltage so there is less headroom. Electrically, they are pretty much equivalent.

Here's a short clip of a 6.5W push-pull 6AQ5 amp I built called the Lucky 7: http://www.macjams.com/song/63549. The topology is 6AK5 (5654) pentode input stage with variable triode/pentode morph control --> variable coupling cap (a la Orange FAC control) for bass --> treble cut control --> 6J6 (5964) floating paraphase phase inverter --> a pair of 6AQ5 --> 15W 5k:8 ohm output transformer with the screens fed via an ultralinear tap on the OT.

This amp has great touch sensitivity. I have since installed a switchable 6AV6 boost stage, so it can go into huge levels of distortion as well. The project was based on a challenge to design an all 7-pin push-pull amp. I'm still not satisfied with the tone controls so I'm planning to pull the FAC and treble cut and install a Bone Ray tone stack (Merlin Blencowe's creation).

There are a couple of pictures + some of the early schematics here: https://plus.google.com/u/0/photos/116886998028395181572/albums/5491186118511677249 I've changed the phase inverter considerably since the last time I posted a schematic, and the biasing on the input 6AV6 stage is considerably different now. I'll have to re-trace the circuit and post updates at some point, along with some finished pictures.

Mason

 

[pucho812]

My old guitar player had a supro with the following tubes in it a 12ax7, a 5y3 rectifier and a 6v6. Said to be 15W more like 5 or 6. Had only 1 knob for volume and the knob also had a switch for on and off. Best sounding amp I ever heard. lay flat on the back pointing up and the tone was heavenly.  got even better when we swapped the 5y3 for a  solid state rectifier plug.

 

[alexc]

Hey Mason

Some really interesting topological travels there - a lot of food for thought for sure.

Gives some interesting directions for my next, more evolved experimentations.

The 6AQ5 and some of the other tubes mentioned makes me want to do yet another small amp (YASA)

Particularly when I can get such nice chassis from ebay seller po1019 "diy tube amp chassis"
I really like to use these.

I look forward to finding the next steps in my travels towards the "best distortion ever" 

Today was my diy BF Super day - clean with some hair and a depth that's hard to beat.

BUT not a small amp by any standards!

Cheers

 

[ruffrecords]

The very first tube amp I built used a 6V6 fed by a 6J7. I built it when I was about ten years old. It was in Practical Wireless in the late 50s/early 60s. It had negative feedback from the transformer secondary and when I first tested it, it hooted like hell!! Most of the problems were due to poor construction technique but I did eventually get it going. I have loved the sound of the 6V6 ever since.

Cheers

Ian

 

[MasonAtom]

Hey Mason

Some really interesting topological travels there - a lot of food for thought for sure.

Gives some interesting directions for my next, more evolved experimentations.

The 6AQ5 and some of the other tubes mentioned makes me want to do yet another small amp (YASA)

Particularly when I can get such nice chassis from ebay seller po1019 "diy tube amp chassis"
I really like to use these.

I look forward to finding the next steps in my travels towards the "best distortion ever" 

Today was my diy BF Super day - clean with some hair and a depth that's hard to beat.

BUT not a small amp by any standards!

Cheers

If you want to go low power, you can also check out some tubes like 6AK6, EL91, EL95, and even 6AK5. I really like fiddling with all of the lower power 7-pin power tubes. Technically 6AK5 is a preamp tube (max plate dissipation is 1.7W), but you can make about a 400 mW SE amp with them, I've done this before and it sounds really crunchy when overdriven.

mason

 

[soundcollage]

I built a beefed up champ style circuit with a SS rectifier and no tone stack that accepts all the standard octal power tubes. I LOVE it. I actually built it for someone else but they never got it. I usually run it with a 6v6 but it's sure fun to be able to put a kt88 in there.

 

[CJ]

now what kind of speakers were you guys using when you experienced tonal nirvana?

 

[JamesW]

Good God Man don't start with the speakers Ha

 

[alexc]

Soundcollage - nice one. Don't you luv the simplicity 
KT88 is a great choice especially with the triode switching - still has some volume.

CJ - open cab 12" with a fender stock speaker circa 1990

Also tried closed back fender 2x12 and a variety of 8" hifi speakers and 12" hifi speakers.

For sure it is not the be all and end all - just nice distortion and surprisingly loud without a tone stack.

My *next* one will be the be all and end all!

 

[soundcollage]

Yes Alex simple, is wonderful. I dont have a pentode/triode switch on mine for that reason- though I imagine it would be a nice edition. My other guitar amp is a self built Kevin O'Connor standard with all film caps and a switching system of my own design (that has individual pent/tri switches for each tube and too many other options ). It takes up every cubic inch of a 17x10x4 chassis. Ironically, I only bought TUT to use his switching design on a orange style amp, but ended up designing my own switching and using his amp circuit (which i found to be more versatile than an orange) because the circuit in the book would not turn off the indicator lights completely and mute each channel. Even though the standard is most likely the best amp I have ever heard I've rarely used it since I built the little guy- mainly because I don't accidentally deafen myself with inevitable volume creep anymore.
CJ my main cab is an old marshall valvestate compact 412 that I put two vintage 30's in the top holes in parallel and have no speakers in the bottom two holes.  (a 'de-tuned' cabinet as suggested by O'Connor) this seems shockingly louder and bassier to my ears than a fully loaded cabinet but ymmv. This was from my first "stack" I got 20 years ago, the tolex was shredded years ago and its covered is spray on truck bed liner now. I convinced my blues playing buddy, whom i gutted and updated a doa princeton reverb for, to invest in a tone tubby 10" hempcone alnico and damn if it isn't huge and tasty in that small open backed combo. Next time i want to spend a bunch on a speaker I'll probably get a 12". On the budget side (though not so much anymore) warehouse guitar speakers sound pretty damn good. I lucked into some 15" ones for almost nothing before they were well known and have put some 12"'s in amp repairs. I'm definitely not getting paid by any of those companies (and realize you were probably just stirring up a pot with the speaker comment).

 

[alexc]

That kevin O'Connor stuff looks interesting - just reading about it now. Maybe time to TUT too!

I'm doing a 15" open back too. But right now, it's a few planks of pine standing against the wall ;D

The 4x Jensen P10Rs alnico in open back natural finished pine that is the diy bf super is pretty damn good too.
Never goes over '3' on the volume tho'. Still, it has a surprisingly thick sound - nothing at all like
a sf twin, for example! Maybe it's the Mercury Magnetics in it. Who knows?

Just been recapping an old sf fender - classic, pre ultralinear 100W with reverb. Doing mods to the bias
and adding a direct out on that one too. Run it with 2 finals pulled.