AC15/30 build Help

[AndyCharles]

I'm looking to make myself an AC15/30.

all I want is the Normal channel with a switch to go between 12ax7 and EF86, half power switch, vol, tone cut, Brite, switch and a tight switch to tighten up/cut the Bass.

Can anyone help with a build like this and how to go about it as a first build.

Should I make a separate 15 and 30 to make life easier for myself? I'm a complete novice other than being able to solder as a guitar tech and having done a little electronics at school.

with No idea where to start and how to use the tag board layout program it would be great if I can get the starting pointers.

Thanks in advance

Andy

[Blueboozer]

Sluckey's Dual Lite is a great design. You should check it out.

http://sluckeyamps.com/dual_lite/dual_lite.htm

[jordan86]

I’d advise you to do a kit. Hoffman, Mojotone and Trinity all offer their spin on a Vox style amp. A kit will simplify everything and you can focus on learning the circuit and completing the build. That’s enough to learn. Sourcing parts and doing a layout on your first build is a steep learning curve. Ceriatone probably has a couple kits as well in that vein though they offer less documentation/support.

I’d pick a kit though and study it til you understand it. And then implement your mods later or as you see fit.

Modifying a kit to add a bright switch and tight switch should be simple enough. The AC circuit probably has a bright cap on the volume pot already. Just put that on a switch. Tight switch would likely just be paralleling two different value caps on V1. Either the bypass capacitor, or the coupling capacitor.

[sluckey]

That's a very tall order for a first project! Walk. Don't Run!

[AndyCharles]

Ok so a kit it is. In the UK there is a train Week Rocket kit.

I believe this is a normal channel ac30 with a Bass and treble control.

Is adding a switchable ef86 to that a tall order to or should I just go with that for the time being.

I just like the idea of volume and cut only.

UK is a little light on kits etc

[sluckey]

Ok so a kit it is. In the UK there is a train Week Rocket kit.

I'm guessing you are referring to a Train Wreck Rocket? Everything you need is available at The Amp Garage. There is a discussion forum and a files forum dedicated to Train Wreck amps. You can find chassis, boards, magic components, etc. It's all there. But it's not a kit. You have to do all the research, parts sourcing, and actual build yourself. Lot's of helpful/savy people to guide you. But you are in the deep end of the pool. Best to already know how to swim. 

[PharmRock]

I’d advise you to do a kit. Hoffman, Mojotone and Trinity all offer their spin on a Vox style amp. A kit will simplify everything and you can focus on learning the circuit and completing the build. That’s enough to learn. Sourcing parts and doing a layout on your first build is a steep learning curve. Ceriatone probably has a couple kits as well in that vein though they offer less documentation/support.

I’d pick a kit though and study it til you understand it. And then implement your mods later or as you see fit.

Modifying a kit to add a bright switch and tight switch should be simple enough. The AC circuit probably has a bright cap on the volume pot already. Just put that on a switch. Tight switch would likely just be paralleling two different value caps on V1. Either the bypass capacitor, or the coupling capacitor.

I started out with a couple of Trinity kits, and they are great.  I was thinking the TC-15 would be exactly what Andy is looking for.  Unfortunately Trinity no longer has this amp as a kit, but the schematic and layout are still posted. In any case, this is a pretty serious build for the first time builder.

[AndyCharles]

Oh the trinity sounds good. Do you have any links to the schematics and layouts.

As for the Trainwrek Rocket I can get a proper kit of that here from Modulous amps. I will check with them to see if it's based on the normal or top boost channel.

Thank you for all being kind and helpfull

[PharmRock]

Go here for docs on the TC-15.  Schematic, Layout, and Builder's Guide is on this page.
https://www.trinityamps.com/support/

the BOM is on page 65 of the builder's guide.

[AndyCharles]

Hi Guys, Im really looking for just the EF86 Channel, vol and tone cut, thats it. Can anyone help with a layout for that. it seems impossible to find for some reason. all the others have so much more going on.

I would be eternally grateful if you can

like the attachment but 15watt and a layout

[jordan86]

This may be of interest to you. Ceriatone  offers this kit.

http://www.ceriatone.com/ceriatone/wp-content/uploads/2021/02/Creme-Brulee-LB-10-Feb-2021.jpg

http://www.ceriatone.com/ceriatone-creme-brulee/

[sluckey]

Time to go to work...

Edit... Revised pdf now includes schematic, layout, and board drill guide.

[dwinstonwood]

Ha! I just literally finished almost the same thing. 

[PharmRock]

I built BrownNote Foxy-18 a number of years ago. Single input, EF86, 2xEL84.   I don't have a schematic, just the layout.
Gain (volume), Tone, Contour, Cut, MV.  it's a great sounding amp, and the MV is very handy.  the 6-position contour control as well as the cut control offer a remarkable amount of tone shaping.
Here's a thread I started over at Trinity Amps when I started this project.
https://www.trinityamps.com/phpbb/viewtopic.php?f=2&t=4194

[AndyCharles]

Time to go to work...

 

You wonderful Human.

Now for a layout and parts list and I get to go shopping.

[sluckey]

Now for a layout and parts list and I get to go shopping.

There's a layout on page two of that pdf. Did you not see it?

That schematic and layout was originally made for four EL84s. I simply eliminated two tubes and associated components and changed the shared cathode resistor to 150Ω rather than 50Ω. You can use a 130Ω like the AC-15 if you like but the 150Ω allows the tubes to run a bit cooler and last longer.

I hope you're up to the task of scratch building this amp, especially the board. I can provide a drill template for the board if you are serious about building this. And remember, THIS IS NOT A KIT!!! There are no step by step instructions provided. You are expected to be able to use the schematic and layout. Layout your chassis to resemble the layout and it will work very well. This will easily fit a 17" x 6.5" x 2.5" blank chassis that you drill yourself.

When shopping, look for transformers that are suitable for the AC-15, NOT THE AC-30. Good luck. Ask questions if you need help.

[AndyCharles]

Ahhh I see it now sorry. I was looking on my phone.

I'm up for the task and completely understand it is not at all a kit.

I do have a free friends who are electronics engineers / ex blackStar tech so I should be ok for a hand.

I'm really looking forward to it. A parts list and drill board would be amazing and I will of course keep the Forum updated.

[sluckey]

A parts list and drill board would be amazing and I will of course keep the Forum updated.

You'll have to make your own parts list and board. I can provide you with a drill guide template, but you must cut, mark, drill, and install turrets yourself. Hoffman sells everything you need to build a board.

[AndyCharles]

Ok I can do that. I have a pillar drill and can make a jig to get everything in line and neat. As for the Transformers if I get a set designed for the AC15 from mercury or Hammond they should be fine?  same with the choke?

[sluckey]

I would not bother with Mercury unless you just like paying twice what it's worth. I used all Hammond iron in my full AC-15 clone. See it here. Lot of good building techniques on that page as well...

     http://sluckeyamps.com/VAC15/ac15.htm

My iron...

     Hammond 270FX power transformer
     Hammond 1650F output transformer (I recommend the newer 1650FA for easier secondary wiring)
     Hammond 159P or 193B choke

PS... All my other AC-15 style amps use iron salvaged from Hammond Organ amp AO-43. Excellent iron and cheaper than buying new Hammond iron.

[AndyCharles]

that's ace I will see what I can source.

I will take a drill template. as for the chassis will a 12inch long chassis be a bit tight. I can get 18 1/2 inch easy here but that seems a bit massive next size down is 12 inch available easily

 

[sluckey]

I could build it on a 12" x 6.5" chassis. I'll tweak the layout and do a drill guide too. May take a couple days.

My Dual Lite is built on a 12" chassis...

     http://sluckeyamps.com/dual_lite/dual_lite.htm

[AndyCharles]

That's fantastic of you. I'm really looking forward to it. If i have a guide for the layout of the chassis and board I can defiantly make it. I have that kid of tooling.

 

[AndyCharles]

just looking at buying the transformers now and read this on the Hammond site,

"Hammond output transformers are well known to design engineers and audio hobbiest alike. Proper output transformer design is crucial to the success of an audiophile quality amplifier. Hammond transformer designs have been proven to meet the test of time. Designed for push-pull tube output circuits, these transformers include 40% screen grid taps for Ultra-Linear operation. Black matte finish. Frequency response 30-30,000 Hz (+/- 1 dB Max ref 1kHz at full output power. Suggested tube types: 6L6GC, 6V6, 807, 5881, EL34. 25 Watts 7K ohms CT"

this info is for the 1650fa, I'm sure its suitable but it makes no mention of el84 and is rated at 25 watt. is this just to over spec for more headroom/dynamic range? is there anything I need to do to make it suitable for EL84s

[AndyCharles]

Ha! I just literally finished almost the same thing. 

So how did it work out? any vids of sounds etc? What transformers did you use? I would love to see it

[shooter]

welcome to the rabbit holes;


what do you want from your OT?
do you want it to saturate and add tone?
Do you want it to simply pass whatever tone you've already designed in?


the UL tap is nice for "options"  I usually build using the UL tap. 

[dwinstonwood]

So how did it work out? any vids of sounds etc? What transformers did you use? I would love to see it

Hey Andy, this is going to be a "re-build" of an AC15/AA964 Princeton hybrid that I built last year. I'm going to remove the AA964 circuits and make it into a more original EF86 single-channel AC15.

Here's the thread for the hybrid build: https://el34world.com/Forum/index.php?topic=26947.0

[sluckey]

See reply #11 for revised pdf that now includes schematic, layout, and board drill guide.

[HotBluePlates]

... read this on the Hammond site,

... Suggested tube types: 6L6GC, 6V6, 807, 5881, EL34. 25 Watts 7K ohms CT"

this info is for the 1650fa ... is there anything I need to do to make it suitable for EL84s

Nothing that you need to do.  It's a 7kΩ primary to 4/8/16Ω secondaries.  The 25w rating is "higher than you need" and the 30Hz to 30kHz bandwidth is "wider than you need."

While it may offer a bolder, beefier sound, your EL84s only care that they see ~7kΩ at the primary.