Where to next?

[Matty_V]

Coming up with ideas for a new build. I've got the parts for a champ type circuit. I want to try out pentodes in the preamp, and make the thing pretty simple. Just something that makes a little noise, maybe have some voicing switches and a cut control to shape tone. Would an ef86 or 5879 be enough to spank a 6v6? Or would I need some more gain from a 12ax7 section?

Just interested in taking a minimalist approach, with a bell or whistle here and there.

[tubenit]

With the parameters of a 5879, Champ style, minimalist .................

I would be tempted to try this.

with respect, Tubenit

[Matty_V]

Thanks, thats kinda where I was heading. I'll use this as a starting point. I'd probably dump the effects loop and go with ss recto as well.

[jojokeo]

Would an ef86 or 5879 be enough to spank a 6v6? Or would I need some more gain from a 12ax7 section?

Matty,
No a single ef86 is not enough to  a 6v6 all by itself. I tried that. It gave out maybe 1/2 to 1 watt of power. I added another ef86 and much much better. I also have used a normal CF afterwards which works well also so tubenit's suggestion would work great too.

[ncusack]

Im pretty interested in this build idea myself so I drew up a possible hoffman sytle board layout for it. Check it out and let me know if I made any royal goof ups.

[kagliostro]

No readable details in layout

please post at least a pdf file with a good resolution

Kagliostro

[Matty_V]

Its good to know my tubes won't be beating each other over the head with hammers while I'm trying to get my rock on.

I can't really help with your layout, cause as it stands I'm the king of royal goofups. Proudly reigning supreme across the land.

Any opinions of ef86 vs 5879? Price comes to mind. I'm leaning more toward 5879 but I'm easily persuaded, which is one reason I'm such a good king.

[phsyconoodler]

Quote:"No a single ef86 is not enough to  violent1 a 6v6 all by itself. I tried that. It gave out maybe 1/2 to 1 watt of power."

He meant in the PREAMP section not as a power tube.

A 5879 will drive the crap out of a 6V6.

[jojokeo]

I guess I should've said that I had a Champ chassis w/ good iron and an open canvass to play with. I wired up v1 w/ the ef86 and used a TB tone stack to the 6v6. It sounded great but only gave about a watt of power. It didn't/couldn't drive the 6v6 properly. Maybe w/out the tone controls it would've been better but I still don't think there would've been enough signal to drive the 6v6 properly.

Its good to know my tubes won't be beating each other over the head with hammers while I'm trying to get my rock on.

There's no "slap" or "spank" icon so gotta use what there is. :)

[TIMBO]

Maybe this is something to consider http://www.el34world.com/Forum/index.php?topic=11628.0

[Matty_V]

Slap, spank, belt over the head with a hammer, its all the same really.

I'm wanting to build a test station similar to the "tube lab #3" setup, so I can try these things out and hear for myself before committing to a solid build.

Then all I'd have to do is nicely ask my basement to stop filling up with water and I'd be all set to conduct my evil tube experiments  

[phsyconoodler]

Quote:"I guess I should've said that I had a Champ chassis w/ good iron and an open canvass to play with. I wired up v1 w/ the ef86 and used a TB tone stack to the 6v6. It sounded great but only gave about a watt of power. It didn't/couldn't drive the 6v6 properly. Maybe w/out the tone controls it would've been better but I still don't think there would've been enough signal to drive the 6v6 properly."

Tell that to an AC15 or an 18 watt with an EF86. You did something wrong.They should be more that enough.

[tubenit]

Ncusack,   Can you post a SCH version?  I can't read the one you put up.  I tried to zoom it larger but was unsuccessful to get a clear enough image of the component values etc...

I appreciate your willingness to share the Hoffman board layout for it.


Thanks, Tubenit

[Matty_V]

The ac15 and 18w have a phase inverter which increases gain though. I'd still be interested in seeing what a 5879 could do to a 6v6 with no gain sucking tone stack in the way. If nothing else just to say I did it.

[PRR]

The first Champ is a pentode into a 6V6.

Every effort made to get the most out of that pentode (no tone-suck, high impedance, no NFB).

There may be a reason Leo soon moved to 2-stage 12AX7 and never looked back. When you count screen-grid parts, the cost is about the same. The available gain is 25 times higher, impedances are lower (better 10KHz flatness), and you have a point in the middle (gain of 50) where you can turn-down before the first stage overloads.

A more versatle amp might be a low-gain pentode, volume, and a low-gain driver into the 6V6. But that is an awkward line-up.

[Matty_V]

That does sound a little knuckle headed. Of course thats never stopped me before.

My main goal is to try out some tubes I've never used before in a relatively simple circuit. Although 12ax7s and el84s are pretty neat I'd like to dip my toe in a different pond for a bit.

[jojokeo]

Tell that to an AC15 or an 18 watt with an EF86. You did something wrong.They should be more that enough.

Thanks phsyco but - umm, there's a difference between a 6v6 and an el84/6bq5 isn't there? Can you tell me what is wrong please? I'd like to know what happened.

*It's been a couple years and I guess I forgot that I did install a tone stack bypass and it still wasn't enough. That's why I remember it being less than a watt and maybe slightly more when bypassed.

[Matty_V]

Hehe, I like turret boards with snipped turrets on it. My 18w ended up way different than I originally designed it, all sorts of snipped turrets, crooked turrets added after install. Gotta love it.

Looks like a nice build, sucky it didn't turn out to your liking.

Something about 'triode stage -> pentode -> cathode follower -> ts -> power stage' is jumping out at me. I think I'll start there and see what happens.

[jojokeo]

Looks like a nice build, sucky it didn't turn out to your liking.

Ahh, but it did turn out very much to my liking...after I added another EF86. This is the first time I defaced something old by punching another socket into the chassis but I didn't deface the faceplate and used one of the inputs. I found a 10" cab for it - better than the standard 8" cabs/speakers and put in a Redfang Emminence speaker. Perfect combo all around and it gets really loud for what it is. Blows away my other "stock" Champs & Vibro Champs for sure. Those little pentodes have an unbelievable tone and vibe you feel in your fingers down into your gut.

[Matty_V]

I like your workbench setup. I was starting to get mine in order and to my fancy when the damn basement flooded. Now I'm reluctant to set up down there again.

I need to get some organizers and separate my resistors and caps by value.

[bluesbear]

"I need to get some organizers and separate my resistors and caps by value."

Meijers, walfart, etc, sell organizers with different size drawers, depending on which you buy. There cheap, though its been a couple years since I bought one so I can't tell you how much. I have 4 and I couldn't survive without them. In fact, I could use 4 more.
Dave

[ncusack]

My layout has been updated in my earlier reply and the .sch file is there too.