I'm thinking of building a Spitfire, but...

[M Fowler]

That sparkly clean is what Dr Z Stangray was looking for with EF86, 12AX7 into four EL84's or the Z28 EF86 and 5751 into 6V6. Also the KT45 and Route 66 all used EF86 v1 with 12AX7 V2.

You might have to add another mid amp tube 12A_7 to get distorting gain.

[topbrent]

Finished. Something's not right. It's sparkly clean to the top of the dial. It's loud. It's sounds really, really, good. But there's no break up anywhere. Start poking around tomorrow. I can't do anymore today.

What did you end up building?

Sound anything like this one?

These pics came from the web a few years back. There was a page up on a EF86 18w lite and this sound file was posted.
Nice sounding and a very clean build.

[pinkphiloyd]

That sparkly clean is what Dr Z Stangray was looking for with EF86, 12AX7 into four EL84's or the Z28 EF86 and 5751 into 6V6. Also the KT45 and Route 66 all used EF86 v1 with 12AX7 V2.

You might have to add another mid amp tube 12A_7 to get distorting gain.

That doesn't really add up to me. I've compared the schematics of the DC30 and the Spit, and I've essentially built the EF86 channel of a DC-30, with two power tubes. A DC-15, if you will. Same PI, same power section, etc. The only difference is I put a Spit tone control after the EF86. So, I wonder if maybe that's sucking signal due to the low output Z of the EF86? That's just a barely educated guess, I'm still pretty new to all this. I want to try bypassing the tonestack and see what happens but the GF is still asleep. Grrrrrrr.

Topbrent, I think this answers your question as well. That sounds really good. If this turns out to be the tone stack, I may just eliminate it from it's current position and place a traditional cut control for tone. Seems to me like that would work.

[crbowman]

I have a modified homebrewed Spitfire that I tweaked to something similar to an AC15 with EF86. I completely removed the master vol, and tone control and subbed in a Vox style cut control in it's place. At about 10:00 it's basically at full volume and just saturates from there. Ridiculous amount of gain, and sounds really beautiful with super nice cleans but very little headroom. I can only assume that you are losing a lot of gain with the tone circuit. FWIW, the cut control works really well. I don't miss the tone control at all.

[pinkphiloyd]

Not the tone stack. I was pulling my hair out and figured out that I had inadvertently placed a 1.8 M resistor to the screen instead of a 2.2 M. Incredibly...all the difference in the world. All of a sudden, there's very little headroom. I may compromise with something in between 1.8 and 2.2. But I didn't do it on purpose. I almost wonder if the resistor package was mislabeled.