more headroom possible?

[Helmholtz]

The 6k6 OTmakes it even worse for EL84s as it means increased plate signal current and excessive plate dissipation at medium output.
With 6V6s a 6k6 OT is fine.

[daz]

The 6k6 OTmakes it even worse for EL84s as it means increased plate signal current and excessive plate dissipation at medium output.
With 6V6s a 6k6 OT is fine.

More reason for 6V6. I'd love to get the right OT, PT and speaker which is what it would take, but I don't wanna spend that kinda money without rebuilding the rest of it which is in horribly sloppy shape. You have no idea ! So we're talking build a whole new amp basically and if i'm gonna spend enough to buy a fender supersonic used, which i was debating before i dusted this ol thing off and started tweaking it, i'd just by the fender. I know those are loud enough too. Then i have an amp thats worth what i paid and if i were to sell it while a home brew is for the most part un saleable, and i know a fender SS has the volume for band use. Guess i'll just S-can the whole el84 idea.

[Chuck H]

FWIW I ran some simulations with your schem and there is no problem with the PI pushing 6V6's to clipping with the preamp set clean. Meaning that your preamp and PI are not distorting ahead of the power tubes with the exception of using the master volume. So you're good to go.

[Chuck H]

And... You really can get more volume using a Vintage 30 or a G12H Anniversary or Heritage.

Is there no way to wire your OT for an 8 ohm output?!? Sorry if this has been covered already. I didn't back read all the associated threads. Because you'll probably not find a V30 or G12H in 4ohms.

[Chuck H]

And... (sorry. I always have an and )

considering that the cabinet is cramped enough that you have to settle the speaker loose on the mount screws before tightening down just to get everything to fit I have to wonder if that cabinet is voluminous enough for the speaker at all? This can make a difference also. If you've ever heard a speaker run without the benefit of a cabinet you'll know this.

[daz]

FWIW I ran some simulations with your schem and there is no problem with the PI pushing 6V6's to clipping with the preamp set clean. Meaning that your preamp and PI are not distorting ahead of the power tubes with the exception of using the master volume. So you're good to go.

Well, thanks for doing that. But i think 6V6's are just not my thing. It does seem the amp still has headroom when cranked loud, but it's not apparently so much that as it just doesn't have much definition/focus. The 84's do. I've been cranking it to the no doubt displeasure of my neighbors. And the conclusion i came to is 6V6's are not great with overdrive preamps. Probably why they mostly use em in fenders. My modeler slayed it when we jammed saturday according not only to my ears but everyone else's. I thought the amp DID have that little something in the top end that modelers just can't copy, but it was lost in the mix unlike the modeler which stays tight and sings when i need it to. Next jam is about 4 weeks and i'll do what i can to it in the meantime and see what works. Less preamp gain is definitely on order because i had to turn that down a lot saturday. But at this point a 20 Lb modeler that sounds as good as it does with built in tuner and every effect known to man and 1 minute setup is hard to beat, so it either has to kill tone wise or it's back into the garage it goes. I have a couple like new celestion 10's i may try and trade for a 100 SPL12" and see how that works out. But having moved to the middle of bumf*ck california the nearest craigslist trader would be 50 miles away at best.

[daz]

And... You really can get more volume using a Vintage 30 or a G12H Anniversary or Heritage.

Is there no way to wire your OT for an 8 ohm output?!? Sorry if this has been covered already. I didn't back read all the associated threads. Because you'll probably not find a V30 or G12H in 4ohms.

Yeah, it has 4 8 and 16 taps. I posted that last post an hour ago but forgot to hit the submit. went to the store and came back and saw i hadn't posted it. Just in case it seems odd after your last posts. And i don't think the small cab is a problem. Some 50 watt marshalls are almost as small. They just place things strategically.

[daz]

Well here's some good news....i have used this 20H choke in a lot of builds and it's always stiff feeling but replacing it with a resistor was never satisfying, that is till now. Maybe it's because it's this is the only 6V6 amp i have done and somehow a resistor works better in it. In any case this really got the amp where i wanted it, as it;s always been much too stiff feeling and sonically it's better too. So i find myself adjusting other things to balance better with this new sound and feel.

However, thats not really the good news i was talking about. Because of this i can remove the choke and the choke is what was in the way of the speaker ! So i can now fit speakers with bigger magnets in it. Theres still a potential obstacle but i don't think it actually is....the frame just touches the OT, but far as i know all regular stamped frame speaker, at least celestion should be the exact same dimensions so i don't think it's a concern. Now my concern is two fold...1-if i buy a speaker and the volume difference doesn't eliminate my volume issue i'm out the $ i paid because i live in a remote area and can't sell gear, at least now w/o a lot of luck. I have 2 10" celestions i have been trying to see for over a years but no one will drive the miles to my area and shipping would take 1/2 my money with speakers, And 2-i have read the SPL doesn't always make the difference in real life as it does on paper. One post i read was someone saying they have tried 3DB higher speakers and a couple times was disappointed to find no real difference.

So i have to consider whether i wanna risk it. But at this point i'm a lot happier with it than i have been so if i can get enough volume to easily work in the band setting i think it could be a winner. Time will tell, but at least now i have the option to try it thanks to losing the choke. (no to mention a couple pounds...that 20H choke is huge)

[Chuck H]

Two things...

First thing is that you are probably lowering the output a little by using a resistor instead of a choke since the the resistor is likely of a higher resistance than the choke and that will reduce screen voltage. It depends on actual measurements and the difference is likely small but in this game of small amps for gigs a watt is a watt.

Regarding the 3dB thing I'll just say that there are some speaker manufacturers that tout their SPL questionably. It should be cut and dry based on strict parameters but I've noticed that at least one guitar speaker manufacturers SPL figures don't seem to stand up when bluntly ear tested. Celestion is NOT that manufacturer. Also, if Celestion is giving the SPL figures for the speaker you have and the speaker you switch to I don't think you'll have that problem. I'd be more concerned if I were changing brands if I only had published specs to work with.

FWIW I did some *outube listening and I think the G12H Heritage sounds most like the G12T-100. But I can't be sure this is your speaker. You've only mentioned that it's a 100W Celestion. What is the model?

[daz]

Yes, it's a G12T100 alrighty. I'm just hesitant because if i buy one and it doesn't add enough volume it's money literally thrown away. As to the resistor, it lowered the plate and screen (why did the plate lower tho, it's BEFORE the reisistor?) voltages by around 10 volts. The other light bulb moment was i removed the 500pf at the second treble peaker and i usually hate EL34 amps w/o them but i guess being 6V6 may be why i liked it. But that wasn't the light bulb moment....that was when it hit me now i have a 440k grid stopped and i remembered i never liked the effect of grid stoppers unless needed to stop blocking or such. So i remove it all and went right to the grid and wham bam TYM, the thing just came alive. I always thought grid stoppers of any considerable size just dulled the tone and when i looked at the two 220ks with not treble cap i was kinda shocked that it didn't hit me till now that i was dealing with a huge grid stopper even WITH the cap. And the kicker is it;'s as bright, no, BRGHTER than i was with the treble peaker but in a different and better way. So the resistors and cap are gone and the tone is so much better it's stupid. Anyways, i have one more challenge....lower the gain a bit without changing the tone in a negative way and pssibly lowering the brightness. Don't wanna do this with a grid stopper for obvious reasons so i have to find another way. Maybe a lower value gain pot to load it at that point. Could just parallel a resistor and get it down to maybe around 250k, tho having done that before i'm not sure it'll work. Anyways, if i can get the gain down about 10-15% i think it's be just right at stage volume. Probably wait about 3 weeks till the next jam to see if i think it's now good enough that i want to get a speaker. Wouldn't mind trying one of those celestion redbacks. Or would the huge power handling mean the amp won't be able to get the most volume out of it?

[Helmholtz]

1W more or less would mean a difference of 0.2dB. Less than 1dB typically isn't noticeable.

A speaker having 3dB more sensitivity has the same effect as doubling amp power.

[daz]

A loss of 1W would mean a difference of 0.2dB. Less than 1dB typically isn't noticeable.

A speaker having 3dB more sensitivity has the same effect as doubling amp power.

30 watts would be great. I did a lot of gigs with pv c30's and no volume issues at all. Plenty of headroom, at least my idea of headroom. Just having a bit of a time finding a used 100db celestion thats is reasonable due to shipping. Gonna do it tho. Maybe a creamback 75 if i can find a used one.