trinityamps.com

Since I've quoted I'll chime in. The amp I built uses a fixed bias output based on the Deluxe Reverb output stage but using 18 watt transformers. I've built a couple of these. The Trinity OT is perfect for this amp. I just used the 8k primary, but I bet the 5k would work well too. I just really like how the amp sounds now and don't feel a need to mess with it.

There's no reason you couldn't modify an 18 watt style cathode biased output stage to work. You'll just need a few changesl. The grid leaks should be changed to 220k, the PI can be changed to the more common 470R/22k pair for 6V6s (or 28k for the second). This will drive the 6V6s properly. Also consider reducing the grid resistors on the 6V6s to 2.7k or even 1.5k.

That chassis looks VERY nice...

_________________
Richard Johnson
-------------------
Playing an insturment doesn't make you a musician, listening does

Thanks. I can hardly wait. That chassis can be & was modded to have both 6V6 & EL84s installed as a prototype.

Update: The sIII is built & working. The octals are in place, heaters connected. I hope very soon this will be working and under test!

I want to be able to switch the 6v6/EL84 in/out - either pair at a time (not both)

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

I'm trying to figure out the best way to use/switch between both.

How do you think this might work out? Changes from stock sIII in Red.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Stephen, that looks reasonable. It is certainly a great place to start. However, I think the .01uf coupling caps are too small. Use .022 for a better low end. Don't worry about flab, since the too high .1uf of the DR is usually the cause of this. I've had a lot of sucess with the .022s.

Maybe you can drive the EL84 sockets by paralleling a seconf set of coupling caps to the EL84 output section?

_________________
Richard Johnson
-------------------
Playing an insturment doesn't make you a musician, listening does

I have an sIII with 6V6 and EL84 power tubes installed. I am running the cathode resistors and capacitors through a relay to ground so I can switch between tubes with a foot switch. The 6V6's are much higher in volume and I would like to bring them closer together so I don't go from normal volume to a roar when switching. I've tried to increase the value of the resistor on the 6V6 set. There's not much differance, I've gone from 250 ohm to 3.5K. Does anyone have an idea on how to tame the 6V6's a bit. Everything sounds great and runs OK other then this.

What happens if you put the 8.2K EL84 grid resistor in there? Sounds like they have lots of drive. Or maybe go back to the original long tail pair PI resistor?

Sounds like they need less drive.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Can you U/L a schematic of the power section. You might need to use a second set of coupling caps, grid leak and grid resistors for the 6V6s. This would let you adjust down the grid leaks for the 6v6s to 220k, which should provide the lower drive you need, while still using 2.7k or less grid resistors. The extra coupling caps will keep the circuits for the two sets of output tubes from interacting too much.

_________________
Richard Johnson
-------------------
Playing an insturment doesn't make you a musician, listening does

Well, I think I found my problem. I have one power tube with some sort of internal short. As it heats up it draws more and more current and the volume increases along with it. I put a bias tester on the amp and could watch the current climb. It actually starts to distort at a point. So, I'm going to order a new matched set of tubes today and see how things work out.

Can't wait. I'm going to wire this puppy up today/tomorrow I hope & lbet & I will test drive ours soon and report back in a new thread.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

My sIII V6 is working as a prototype.

I left the LTP at 56K . If we want more drive, I'll add another 56K in parallel to the LTP and see how it goes.

I simply added another 120 ohm cathode resistor in series with the one for the EL84s so the cathode bypass cap only is working on 120 ohm cathode resistor.

Used 1.5K grid resistors to the 6V6s

Used NOS Sylyania 6V6s

Rest is stock sIII

lbet is coming over to test drive it this weekend. If we both like it, it'll get cleaned up and put into service.

Probably make it switchable. Right now, if you want V6 power, you have to plug them into the spare octals I installed in the new, modded chassis, and remove the EL84s.

Oh yeah, and I better put his boost switch in before he gets here.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Gents, I don't suppose you could make a few sound clips for us on the 18 watters running EL84's vs. 6v6's could ya?

Well, we want to but lbets recording studio computer is down and out. As soon as it's back up again, for sure.

I took mine (now called the sIII v6) to get an opinion from Rob Baker from the Tragically Hip. He already has one of my 30 Watters. After 45 minutes of playtime, he wanted one, so I'm thinking, this is winner! Duhh

It deserves some serious clips.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

For sure! He's got a nice smooth tone so if a guy like that who doesn't muck his sound up by running it through a rack of effects likes the tone, then i think I know which version I will be going for. I take it these 18 watt flavours take booster pedals well? some times for some extra lead its nice to have...

The 18 watt is very good with boost pedals. I even play around with a treble booster on mine, just to do the Brian Mayish thing and is great. However, I really like it with just a chord and the guitar volume control.

_________________
Richard Johnson
-------------------
Playing an insturment doesn't make you a musician, listening does

Oh yeah, he wants the Boost Switch Option too!

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

I will be working on the pc this weekend. I anticipate clippage early next week.

LB

I'll be waiting here with bated breath. (Or at lease breath that smells like bait. )

LeeMo

Another vote for boost switch here.. would love to have the option on an amp running 6v6's!

I'm working on foot controlled EL84/V6 switch and the boost switch now. Currently, just toggled On/Off, but these will be electronically controlled.

Can't have the roadies flipping switches on stage now can we?

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

"Sod 'em, they get PAID" - Pete Townsend...

_________________
Richard Johnson
-------------------
Playing an insturment doesn't make you a musician, listening does