Best 6V6 Single Ended Voltages?

[ncusack]

Hello,

Im just wondering what the general concensus might be for plate and screen voltages for single ended 6V6 power section. I know in the end its all about hitting that happy dissipation value but im curious about where people have settled for this kind of setup.

To be more specific im curious about new production tubes like the JJ and Electro harmonics 6V6's.

Cheers,

Neill

[firemedic]

Still workin' on it I see!
Mine is at 370v plate-to-cathode, w/ screen within a couple volts of that. It sounds really awesome but I think I'm eating the tube up, right at 100% diss.. The printed 6V6 EH logo is fading fast. I'm gonna try to drop my entire B+ @35-40v w/ a zener between the PT CT and ground.
I have a 220R 10W resistor right after the 5Y3, which drops 10v or so. I turned it all the way up & got this awesome sag on the hard notes! But I'm really afraid it's not stable & runs too hot.
Anyway, hope that helps....

[ncusack]

Yeah with the new plan im thinking about using a 5u4 in the HoSoSE build. It should give me about 345 at the first node so probably about 330-335 on the plate. Screens will be pretty close to that and then preamp should fall in line. Im just curious what other peoples experience has been so thanks again for the response firemedic.

[tubenit]

OK, I acknowledge my response is a little off topic but hopefully it will add something to ponder.

In every push/pull amp I've built where I have installed a VVR,  I have liked the tone of the amp with the power tubes at a lesser voltage than without the VVR.  I don't remember exact voltages but on one amp (for example) without the VVR, it was around 390v and I like the tone "better" around 270v (IIRC).

Having said that, I find that I need the preamp or overdrive voltages about the same whether push/pull or single ended.  Just food for thought.

With respect, Tubenit

[John]

Tubenit, that does give me something to think about. Maybe I'll put the NOS tube back in, re-place the original value dropping resistor, and listen some more to mine (albeit it's got el84s) Sometimes tinkering is as much fun as the playing!

Thanks yet again for all the contributions you and everyone else make so freely here!

[jojokeo]

Still workin' on it I see!
Mine is at 370v plate-to-cathode, w/ screen within a couple volts of that. It sounds really awesome but I think I'm eating the tube up, right at 100% diss.. The printed 6V6 EH logo is fading fast. I'm gonna try to drop my entire B+ @35-40v w/ a zener between the PT CT and ground.
I have a 220R 10W resistor right after the 5Y3, which drops 10v or so. I turned it all the way up & got this awesome sag on the hard notes! But I'm really afraid it's not stable & runs too hot.
Anyway, hope that helps....

Why worry about dropping voltage because of your situation? You should consider lowering your power dissipation from 100% instead by increasing your cathode resistor value.

[firemedic]

I want to drop PA voltage too, so instead of lots of dropping resistors I'd rather try a lower B+ to begin with. Plus I've never tried this method & I like messing with my amps.
My cathode resistance is now 740R, I don't have any higher values on hand.

[labb]

I think that I would just invest in one of Hall amplification VVR's and dial in the voltage that I thought sounded the best.

[jeff]

I was thinking of this today. Say you use a VVR to drop the voltage in a champ to 250V, I don't think that's the same thing as building a 250V amp. In a champ you usally use a 7K transformer and a 470 ohm cathode resistor. With the VVR you're lowering the voltage but not changing the tran or cathode resistor. If you were to build a 250V champ you'd probally use a 5K tran and a 250 ohm Cathode resistor.

But I think the VVR works because to some extent it balances it's self.

Start with a 250V 5K 250 ohm amp, ideal setup. If you replaced the 250 ohm cathode resistor with a 470 ohm you'd be biasing cooler. The tube is no longer center biased. In order to keep the tube center biased you could replace the 5K with a 7K tran. This is the same conditions as using a champ with a VVR turned down to 250V. Both setups work, but I don't know if they're the same thing.

Even though both amps are running at 250V the amp built for 250V would be biased at 100% and the VVR turned down to 250V would be biased cooler. It may be an apple to oranges thing. They're both fruit(250V), but are they going to taste(sound) the same?

I don't know if this makes a difference. What do you think?

[jojokeo]

Personally speaking, I've built a number of lower powered amps specifically to use various power tubes for varying output power levels. Where I thought there would be greater tone differences, there really wasn't as much as I'd thought prior to completions. They do have a bit different characterstics but not as much as you might think. I've switched the output speaker jacks w/ an 8ohm speaker to the 4 & 16 ohm taps and there's very little differences to be noticed in most cases there too.

With using VVR, I've noticed that as the voltage was lowered for the first 1/4 to 1/3 of rotation of the control pot, there's almost no noticeable difference in tone or volume. Then when I get to half-way, the output power starts to get noticeably less, however the threshold of the amp staying clean gets less and distortion/overdrive tone begins to increase losing headroom. This amp doesn't have a master volume as the vvr control IS the master volume.

As this relates to the earlier comment of an amp built to 250v vs the amp lowered by vvr to 250v - you may not hear enough of a difference in that amount of change until maybe you start to get to around 200 volts? Or the vvr'd amp may start to get earlier break-up compared to the one designed to 250?

[labb]

" however the threshold of the amp staying clean gets less and distortion/overdrive tone begins to increase losing headroom".

What if you just control the voltage to the Power tube? I have an email into Hall right now for one of the VVR3's. I've got a 5F2-A that I am going to play around with. Probably already been done but I can't find the results.

[jojokeo]

What if you just control the voltage to the Power tube?

That's what was done. It only lowers the voltage to the plate and screen, not the preamp.