Anyone built an AC-15? (Awesome new Lil Dawg content)

[King Fan]

I've mostly built, and mostly seen Fender builds here. We also see a decent number of Marshalls, and of course some Gibsons, Valcos, Spitfires, etc. But not many Voxes, methinks, and for me at least, that's a tone country I'd like to visit.

I came across this prototype AC-15-style build by the amazing Jim Nickelson at Lil Dawg amps (no affiliation). He did this prototype as a 'lunchbox' head, and notes it has normal & top boost but not the tremolo channel. I can't say how closely the circuit follows the AC-15, but I always admire his builds, and I see he's adopted even more cool build practices here, like filter caps near their sectors.

He says, "I was pleasantly surprised with a great sounding amp full of the Vox tone that I had been missing from my line-up for so long. So it’ll be available in my catalog of circuits as a LunchBox head for now, and maybe a head or combo if I can find a suitable chassis to work with." If you're interested:

AC15 LunchBox - Lil Dawg Amps & Pickups

While I waited for some parts to show up I remembered a friend asking if I ever thought about a Vox AC15 style build. I had a number of times but finally thought today is the day to work out the details for the build. The layout seemed fairly straightforward to me as I’ve done so many LunchBox...

www.littledawgamps.com

 

[toanhunter]

I've been tempted by this: https://modulusamplification.com/rox-15w-tone-boost-valve-amp-kit-3396-p.asp as my first amp kit build.

 

[Whoa Tele]

Jim’s a righteous dude .

 

[Mr Ridesglide]

King - I wish you would take a look at the Creme Brûlée from Nik at Ceriatone. I pretty much took his ideas into an old record player years back. I gigged it with a 2-12" Cabinet and it was very sweet. I put my Bad Cat Black Cat 30, made by Mark Sampson away, and used that little amp until I build a '59 "Pro" that I absolutely love. That EF 86 Channel is a great tonal giant. My Bad Cat has a EF86 channel as well. This amp from Nik has a master volume and a boost pull out knob. It's killer.

 

[Mr Ridesglide]

I didn't use Nik's layout, but put all those caps on the board instead of the switch itself.

 

[elpico]

I played with vox circuits many years ago. So many famous names have been associated with them, and there's no denying how dang cool they look, but if we're talking about faithful clones of the 60s circuits? I learned that's not for me. The vox tonestack is just straight up broken. Even the "fixed" version is pretty inferior to the Fender/Marshall one. And I have no idea how the top boost channel got so popular, that 1st coupling cap is too small for any guitar I've owned. Should've been 1n at least.

The current stuff seems to go more vintage "inspired" than direct clones, and that's probably a good idea

 

[King Fan]

Good points; Jim says his is Vox *style*, not necessarily a straight clone. I’ve seen other criticisms of Vox circuits. So I think the ideas above about successful modern *takes* on Vox tone would no doubt be a smart starting point for a build. But the scale and relative simplicity of Jim’s build look ‘do-able.’

 

[Vibroluxer]

Jim a builder of the highest degree and is a sweet man to boot.

 

[chas.wahl]

Steve Luckey did a version of the AC-15 (and AC-30) over on EL34world.com a decade back.

Sluckey's 1960 Vox AC-15 and AC-30 (Marshall style)

Hoffman Amplifiers Tube Amp Forum, Sluckey's 1960 Vox AC-15 and AC-30 (Marshall style)

el34world.com

There are also quite a few threads there concerning builds by forum members.
His amps website seems to have been taken down for awhile, but the basic files for the AC-15 are available as attachments in his post of the thread linked-to above. He calls his version "1960", though sniffing around in other schematic files I've found suggests that the schematic he used (and includes, though bearing no date) is a slightly later iteration, later than sometime in 1961. He also suggests some mods as part of the package.

Oh, for access to SluckeyAmps.com as was, there's always the Wayback Machine, I guess -- but it would be nice if someone (with Luckey's permission, of course) could archive his stuff somewhere.

 

[toanhunter]

this looks really good as well, if you are after an AC30 style amp https://modulusamplification.com/wr...-head-kit---optional-master-volume-3229-p.asp

 

[mk_716]

Hey @King Fan ,
I've got a copies of two sluckey variations a single channel ac-15 and a single ac-15 with a matchless reverb.

P.m. me if you're interested.
m.

 

[Vibroluxer]

@mk_716

Exactly what I love about this place. Good on you, Man!

 

[King Fan]

Steve Luckey did a version of the AC-15 (and AC-30) over on EL34world.com a decade back.

Thanks. I’d totally forgotten that one. His builds are inspiring.

 

[dougsta]

I'm up for an early AC10/AC15 design, with the EF86. I'm learning to use KiCad to do a very simple vintage style strip board of 2 x 33.
I can get 5 boards from the usual Chinese PCB manufacturers for £15 delivered to my door.


The AC10





Here's one I got made for 2 x 30 with 'eyelet' type thru holes as a test.





I also added in a Bassman 5F6A on a single board (not my design) to the PCB order to test the quality of PCB manuafacture - all very good, again £3 each board. A future project I have in my head - JTM45/5F6A.

 

[timbraun]

I found a Brown Note Foxy18 at a local shop, which was / is based on the ac15 ef86 channel. Love that amp.

The schematic / layout was published for diyers. It'll take a little searching to get that. I was getting ready to build it when I stumbled across the built one in the wild.

Here's the schematic in layout form, the only schematic I've ever found for my amp:

El34 world foxy18 schematic image

 

[Pete Farrington]

The vox tonestack is just straight up broken. Even the "fixed" version is pretty inferior to the Fender/Marshall one

Could you explain your thinking there, and what's the fix (I'm just wondering )?

I have no idea how the top boost channel got so popular, that 1st coupling cap is too small for any guitar I've owned. Should've been 1n at least.

My take is that the Gibson tonestack Vox used tends to be somewhat bassy.
All in all, it's not dissimilar to using a Rangemaster in the normal channel, which was a pretty popular thing to do through the 60s and 70s, and yielded some successful tones (including that of my hero, Rory Gallagher ).

And for the past few decades, Tube Screamer based pedals have been a popular 'always on' option, and their bass cutting shelf filter has a similar effect to the Vox brilliant channel's high pass filter.

 

[elpico]

Could you explain your thinking there, and what's the fix (I'm just wondering )?

I'm not referring to anything new or exciting there, the tired old debate about whether Vox knew they were copying a couple errors when they cribbed the "top boost" channel from Gibson. The super fans will tell you the Vox guys knew about the tone stack error but are such geniuses they recognized that the error makes it "better" and decided to keep it. The standard "It's not a bug it's a feature!" defense. The rest of the world wonders if they had such electronics geniuses working there, why did they need to copy the whole design from Gibson in the first place?

That 1st coupling cap value is different. The tone stack is objectively messing up and adjusting ranges that the knobs say it shouldn't, but the coupling cap is purely subjective. I'm just not a big enjoyer of thin guitar sounds. 1n isn't a big increase, but it's noticeable. First time I built a top boost channel l almost immediately added an orange style switch for that 1st cap. Think I put I values between 500p and 5n on it. It was never in the 500pf position. I have a feeling anybody who had that knob on theirs would say the same.

I only commented because Kingfan was wondering aloud why we don't see more Vox builds. I'd say the reason is cause they're kinda hit and miss. They had the best marketing hands down. They look amazing and they paid the right people to put them on stages behind the right acts, but they didn't even know how to make a bright channel? I think a lot of new guitarists and builders *think* they're going to love Vox circuits, and then the reality is kinda "huh. This needs work.."

 

[King Fan]

I found a Brown Note Foxy18 at a local shop, which was / is based on the ac15 ef86 channel. Love that amp.

The schematic / layout was published for diyers. It'll take a little searching to get that. I was getting ready to build it when I stumbled across the built one in the wild.

Here's the schematic in layout form, the only schematic I've ever found for my amp:

El34 world foxy18 schematic image

Nice, thanks -- schematics are great for understanding a circuit, but for actual building it's very helpful to have an actual layout like you shared. IF I ever decide to build one, I'm gonna have that in my files for comparison to others like Sluckey's.

 

[Uffepungen]

I found a Brown Note Foxy18 at a local shop, which was / is based on the ac15 ef86 channel. Love that amp.

The schematic / layout was published for diyers. It'll take a little searching to get that. I was getting ready to build it when I stumbled across the built one in the wild.

Here's the schematic in layout form, the only schematic I've ever found for my amp:

El34 world foxy18 schematic image

Very cool that you found that amp! Many years ago, when I was just starting to getting into amp building, I decided that one day I would buy a Foxy18 kit. When I finally had the cash, I read so many online reviews of how people never got the order that they had paid for. So didn't dare to buy one

Didn't it have some sort of "brown switch"? Maybe it lowered the B+ or something like that?

 

[Kev-wilson]

I built the Sluckey AC15 lite (with the Marshall 18 as a second channel), it's the 1959 version iIrc using the EF 86, and a take on a 6 position rotary tone control which I think comes from the Matchless, the schematic and layout are on my thread about the build, it's a nice 'Voxy' sounding amp.

Clip of my mate playing it.