Most of you might be able to put to rest the whole, "There are no dumb questions," thing, 'cause I think I just asked one. Anyway, all jokes aside, what's the allure of the EF86 option? What is the tonal difference between one with EF86 and and one without? Now... we wait.
In the typical Vox style preamp you get an EF86 and/or a 12AX7 channel (normally refered as a top boost channel) In these preamps one EF86 provides almost as much gain as the top boost preamp, made of 3 stages of amplification. The gain that the EF86 provides has a quicker attack and a generally snapier character. Another big difference in these two is that traditionally the EF86 preamp only has a tone control, which is a high pass filter. Therefore you get a much broader and flatter frequency response. The top boost preamp has a Treble/Bass tone stack, which creates a mid scoop and an attenuation of the signal. So, EF86 is higher gain overall, fast response and big touch sensitivity, flat and full freq response. 12AX7 (top boost) is your normal clean/crunch tone, with a bright and scooped tone shape.
I have an EF86 in my Hayseed 30 and it is a darker, mid heavy tone, more like a Marshall. It also takes dirt pedals amazingly well. Through the Top Boost channel, dirt pedals are a bit 'buzzy', though I love the Top Boost channel for clean stuff.
I think... and not disagreeing here... 'jes saying... the circuit is the first "decider" of tone, right? I had a custom Morgan DAG15 that had an EF86 in V1 and it was fairly top end heavy. A potential buyer called it "shrill." (Said potential buyer being a WAY better guitarist than me.) I sold it to Crowder here and I'm pretty sure he moved it on "right quick" too. Only point I'm making here is: it surely didn't seem to make the Morgan amp darker... But not having a 12AX7 DAG15 to compare to... I should prolly 'jes keep my yap shut. lol
I have a Fargen Custom AC15 with only an EF86 preamp, no tone control, just a Cut control and a Bright switch. I would certainly not call it darker. I would say it is "thicker" sounding then a To Boost preamp. It does take pedals better IMO, and to my ear sounds smoother are less fatiguing to listen to. Keep in mind that EF86 tubes are notoriously microphonic, so they can be problematic in a combo, but if you get a good one (I use NOS RFT's and Teslas) the sound is glorious!
I can only use the old AC15H1TV I had as an example, but I found that the EF86 channel was thicker, better balanced from the lows to the highs, a bit smoother on the high end and subsequently enough, took pedals a little bit better as well. The 12ax7 side definitely has a bit of a mid-scoop, the high end comes out a little bit thinner with a more aggressive bite. When I first got my Vox, I liked the 12ax7 side, but as time went on, I preferred the more neutral flavor of the EF86. Hope that helps!
Both my Morgan's (Dual 20 and AC20 Deluxe) have a switchable ef86, and it's the only mode I use. Nice fat tone with more gain on tap. I'm surprised more boutique builders aren't utilizing them.
For me, the EF86 seems to be a little more HI-FI on clean settings in the right amp. Almost like going from FM radio to a CD (or high quality .wav file), not a big difference but definitely noticeable. This would be in amps like Dr. Z Stangray, RxJr, Gabriel Voxer, Winfield Cyclone, Matchless DC30, ect.... In other amps based more on the actual Vox circuit it's a darker channel..... Like in my Hayseed, the EF86 is a darker, thicker channel... When I jump the TopBoost (12ax7) and normal (EF86) channels, this is total magic. You get the 12ax7 bite and the EF86 thickness and the two different breakups going on together. I found similar results in an AC15H1TV and AC30H2 I had a few years ago. I also like EF86 tubes because they have a different gain structure to them that you can tell the difference even at slightly hairy settings. When fully cranked up, there is more gain than a typical 12ax7 and most of it seems to come at the last 1/4 of the volume knob. I told myself a few years ago "I will never own an EF86 amp" because of the cost of the EF86 tubes. After I got one, I said "I will never own 2 EF86 amps". Currently, both of my amps are EF86 amps. It's one of those things that you either like or don't like and you really won't know until you actually play one for yourself. After playing amps with EF86's, I find it hard to play straight 12ax7 amps. Just my $.02 worth
ayep. EF86 is thick/meaty/throaty. in the vox context comparatively, the 12AX7 in its respective channel is chimey/bell-like/clear. which is a departure from what i usually think of, since i use fender amps and the 12AX7 in a tweed usually brings the rage when cranked, and I have to tame it with lower gain tubes sometimes. just an example of how different amps can have their own signatures even when using the same tubes.
In my D/C-30, I use the 12ax7 side for rhythm and the EF86 for solos. One side has more chime, the other has more gain and a fatter sound.
I have the Bad Cat Black Cat 30R. Very different flavors for each - but typically more gain on tap, significantly more low end, more dynamic level of break up on the EF86. The 12AX7 gets used for my "clean" channel.
