lego's spin on Sluckey's AC15

[lego4040]

With one daughter in High school and two younger daughters, you do see women from a different perspective.

[sluckey]

I've put together a webpage for my AC-15 build. Here's the link...

     http://home.comcast.net/~seluckey/amps/VAC15/ac15.htm

This is definitely my last amp. The fire is gone.

[lego4040]

That is awesome Sluckey, I hope another amp inspires you to build so we can follow along. When I get back my transformers will be there at my friends shop. Eds faceplate will be there in my mail and all I will be missing is the 3Rma pot. I don't have enough amp builds to retire. This is my second amp and it's my first scratch. I just found the Gibson GA16T &18T are their version of the tremolux's. I found the sch layout here and will try and find some YouTube vids of one

[sluckey]

I hope I put together enough big pics to be of some use to you on your build. And as always, if you have questions, ask away.

If you look at the top side of my chassis, there's plenty of room to put the cap board/doghouse on top. That will free up a lot of room inside the chassis. You will appreciate that. Just be careful and plan ahead when you start drilling.

And when you start working the faceplate, I highly recommend at least a 10" 80 tooth carbide tipped blade. And brad point bits for the holes.

[lego4040]

Done and done. Not sure where I'll put caps

[dbishopbliss]

Question about the 16uF capacitors C10 and C15... Are these the dual cap can? Hoffman seems to only carry the 32uf dual caps... will these work or should I look elsewhere?

[sluckey]

Are these the dual cap can?

yes. AES has them.

[lego4040]

My bad I read your question wrong, Sluckey's cap is dual. I might go that route next build

[Ed_Chambley]

I've put together a webpage for my AC-15 build. Here's the link...

     http://home.comcast.net/~seluckey/amps/VAC15/ac15.htm

This is definitely my last amp. The fire is gone.

SLuckey,
Even I have made the comment.  I said I was only going to maintain what I had and sell most of that.  The fire is gone.  My wife laughed out loud.  You see, every time we are somewhere like traveling through the mountains and we stop at a place that has old stuff around (here in the city they call them antique boutiques) I am drawn to ice cream and things with tube in them.  Cant help it, I just like the stuff.  Doesn't matter if I buy it, I usually do not, just like looking.


Every once in a blue moon I stumble across "the thing".  Most of the time it is a radio, I will admit.  Like Jojokeo said to me, you have played or owned about every amp.  This is true and after a while it really has to spark something to get me motivated enough to build it for myself.


I love the archiving you did mentioning Barry.  He must have been a large influence on the guys here on Hoffman.  He came back around just long enough to get the interest in this build.  I was new here and watching and wondering if the amp would get built as it has a lot of parts just to be a 15 watt with a wiggle.


I don't really know why this amp is a difficult build, but it is.  I have not taken the first photo, but I will as I am just at the loaded board stage.  I have built some cabinets, but that is just photos of wood.  When complete I will post photos.  I think the complex scratch build just takes too much out of me and I have to do thing I don't like to get to do the thing I do like and that is more like a job than hobby.


Stay with me. 
When the complex scratch is done, it still is not a 1960 Vox AC15.  If I found one needing some TLC next weekend I would probably repair it and put off to the side the scratch build.  That is the difference to me.  It has something to keeping the history alive that a clone can never do.


However, that being said.  No one is making a kit, but it wouldn't take much for Mojotone to add this and an AC30 version to their kits.  Wonder if anyone is watching this with the idea in mind?

[TNblueshawk]

Sluckey, fantastic work. Really makes me want to open up my wallet sooner rather than later and build this.
 
By the way, since your chicks are figthing I figure you have 3 choices. One, do what you did. Two, get a little red rooster to keep them in line. Three gets some mini chicks from Small Bear
 
http://www.smallbearelec.com/servlet/Detail?no=1190

[sluckey]

I didn't even know there were any mini chicks. Got some ordered. Thanks for the tip.

[Willabe]

AES has them too.


            Brad     

[lego4040]

Ed I just got home and opened the faceplate package   what size table saw blade did you use again it rip it down?

[sluckey]

I used a 10" 80 tooth carbide tipped blade. I also screwed the faceplate to a 1x6 sacrificial board to act as a carrier to make handling easier during the ripping process. Very little filing needed. More like removing the burr edge from a freshly sharpened knife.

[Willabe]

I used a 10" 80 tooth carbide tipped blade.

Teeth forward or backwards?

We always cut aluminum siding with the carbide tipped blades teeth backwards.

Now that was a thinner stock.

I also screwed the faceplate to a 1x6 sacrificial board to act as a carrier to make handling easier during the ripping process.

Makes good sense as cross cutting a long narrow piece will very much tend to bind and kick back as apposed to cutting a long narrow piece of stock that will smoothly go through the cutting without binding and kicking back. Kick backs not only will mess up the stock but more importantly can and will hurt you VERY seriously!!!!!

Did you leave the face plate hanging over the 1"x6" a little bit so as to only cut the face plate or did you cut through the board and the face plate at the same time?

I think most of you know this but, please remember ONLY leave any circular saw blades teeth extending past the stock as little as possible for safety.   


                  Brad       

[sluckey]

Blade was not installed backwards. I've done the backward blade before on some 1/8" thick aluminum. That generates too much heat for me and does not give as clean a cut. I didn't want to risk burning the ink.

The long edge of the faceplate hung over the edge of the 1x6 by about 1/16". This was done so the faceplate (not the board) made contact with the fence for a true rip. I cut mine on a radial arm saw with the faceplate facing up. Blade was set to cut through the faceplate and about 1/16" into the 1x6. I used a featherboard and push stick to insure a good rip and constant feed rate.

To duplicate what I did on a tablesaw the faceplate would be facing the table with blade height set to just cut through the faceplate and not all the way through the 1x6.

[lego4040]

I've gotten kick back before, I always try and stand to one side so if I got to move fast it's only a little. Where did you screw plate down, did you use center of pots?  I will probably cut it in half then trim. I have a good 10" blade but not carbide tip

[sluckey]

I screwed it in the white waste area at each end of the faceplate.

[Ed_Chambley]

I use the same blade as Sluckey, but have used a rip blade as well.  It is just aluminum.  I don't do anything but put tape on the face.  I have a Jet eXacta 50" cabinet saw.  It is an old one, and very heavy.  I have also cut them on a Delta floor model, US made and heavy as well, but not a cabinet saw.


I run the blade down.  I use it to cut steel pipe poles for closets.  I also use a chop for the same.  I cut metal a lot.  I actually use the table saw to cut my chassis and to make the holes for laydown transformers.  I drill 4 large corner holes and raise the saw blade into the metal while holding the metal down.


My point for saying all this is cutting aluminum or pot metal is not a problem with a wood saw.  Actually cutting Maple or 3/4 inch Birch is harder.  Just move it slow.  I cut yours and Sluckeys in half before I shipped them.  All I did was set the rail, turn it on and cut it while all the time WEARING SAFETY GLASSES!!

[lego4040]

My iron came in and its time to tape chassis up and measure things out and cut faceplate

[Ed_Chambley]

The rest of my stuff is on Fedex for tomorrow delivery.  The only thing left is the last order which contains all the stuff I forgot about.  Really I have everything I need now, I just wanted to use Teflon Hookup wire in a nice color scheme and I did not have enough colors.


I see where Sluckey used all white on his pots.  I am going to use White on the normal channel, but I am waiting on purple for the VIB channel,  You know purple conducts mojo best.  I may use a combo of purple come to think of it.  Everything carrying the signal may get purple, and yes I do have some purple spaghetti to cover the shielded cable.


Truth, I am waiting on some Teflon and my OT which will deliver tomorrow.  My progress is going to be much slower and will be in a new thread.  I promise you this, the Long Board version is a great idea until you begin loading the thing.  I was working for 4 hours and sat back and was only a little over half.  Done now, but I still have to put the leads on and solder everything.


It really is a very cool, but involved build.  My first ever build was a Marshall 1987 circuit.  I applause you for taking this in as your first scratch.  I have done many scratch builds now and this one is really involved.  Not saying anyone cannot do it, just saying be ready for a lot of work.

[lego4040]

I did some mocking up and this is what I got so farso I started with board placement, then sockets which start 1.5" of edge then every 2". From faceplate to board will give me approx. 1.5".  As for tranny I'll keep them like Sluckey's. Suggestions welcome. Oh I can either put cap board inside right next to main turret or dog house it?

[lego4040]

Question, on long board version you have 330K resistor going to preamps EF86 pin9 and 12ax7 pin 2. What's the reason? It's not in your original and should I do it anyway

[sluckey]

Question, on long board version you have 330K resistor going to preamps EF86 pin9 and 12ax7 pin 2. What's the reason? It's not in your original and should I do it anyway

Those are 33K. They replace the 68Ks that were on the double input jacks. My single input jacks are wired as high inputs. On the original when you plug into the high jack the 68Ks will be paralleled for a combined resistance of 34K. So I just used a single 33K to replace the two 68Ks. And I moved it to the tube socket rather than leave it on the input jack.

If you will have high and low jacks (total of four) you don't need the resistor at the tube socket.

[lego4040]

My bad on color code, I am gonna take this next measuring part real slow. I've never scratch built a chassis but I have messed up the occasional stomp enclosure.

[lego4040]

Need to make and order that 33k value change as well as that 220k on speed pot

[lego4040]

started center tapping for hole drilling, man this is nerve breaking stuff. Im going to have to use the dog house method fr the main caps. no room for a newbie in their. I misplaced all my grommets

[dbishopbliss]

started center tapping for hole drilling, man this is nerve breaking stuff. Im going to have to use the dog house method fr the main caps. no room for a newbie in their. I misplaced all my grommets

Anyone know of an inexpensive way to practice chassis drilling?  I think I want to build this but I don't want to mess up a $50 chassis while I'm learning.

[dbishopbliss]

I should have thought of this before... people are selling 9x12 remnants of 0.09" 6061 aluminum on the bay for $6 plus shipping (another $6).  That might be expensive for 1, but if they will combine shipping then buy 5.  This will give me plenty to practice with and some left over for other projects.

[sluckey]

I drilled every hole on my chassis from the outside. You can sometimes get into trouble drilling the inside. Most holes were done at the drill press.

I like to use an automatic center punch to mark the hole location. Then I drill a small pilot hole. If this is to be a screw hole, then I use the correct size bit for body or tap size. If it will be a 3/8" or larger hole I enlarge my pilot with a #1 bit, then I switch to a step bit. I highly recommend using a step bit for any holes bigger than screw holes. Greenlee is my choice. That means holes for pots, switches, grommets, sockets, jacks, etc. The step bits are easier to control than a twist bit and do not grab just as the bit breaks through like a twist bit will. Using a 1/2" twist bit to drill a hole for a switch can ruin your day!

Whatever kind of bit you use, always hold the chassis firmly and just apply steady pressure with the press. Don't strong arm the press! This chassis can be kinda awkward to cut on a small table top press. Get a piece of scrap wood about 3/4 x 8" x 30" to go between that small table and the chassis. That will help you maintain control and keep the chassis perpendicular to the drill bit.

Tip for using the step bit. Let's say you're ready to drill the 3/4" holes for the sockets. Wrap a piece of masking tape around the bit to cover up all the steps that are bigger than the 3/4" step that you want to stop on. Do the same for 3/8" holes but only leave the 3/8 and smaller steps exposed. And use a slower speed.

[lego4040]

    Ok guys, I got some done. Once I drilled that first hole there was no stopping. I did my best and did a quick mock up. I still have to do face plate and order smaller standoff for the main cap and the dog house. I swear I was shaking, I did tap all holes except the Trannies. I have to resize them first then will post. Yes its MIller time, more like Lagunitas

[sluckey]

Nothing to it man! You just got through drilling over 100 holes on that fiberglass board and that looked good. You're a pro. I'm drinking an Ice House with you.

I think I have the same little drill press you have. Mine is a 25 year old Delta.

[lego4040]

i added the missing standoff but need smaller ones and need to drill a hole to pass wires thru. I also cheated and tapped all holes with a very slow speed drill

[lego4040]

I bought a spring loaded center punch and I have really good step bits that I use on electrical panels. I did cheat and go free hand instead of press.

[sluckey]

That looks good. Take a break. Dream about your next step. 

[Willabe]

Come on now, even when your just testing the lay out, use the rubber grommets, so you don't scrape the PT's or any other wires insolation.

Other wise, looks real good to me!

                     Brad           

[Ed_Chambley]

Looking good.  Those 9 pin sockets look real nice all in a row there.  Where did you buy those?  I will run our of all my nice ones on this build and will need to order some.  You guys seem to leave the tape on there longer than me.  Do you take the parts back off to remove the tape, or will it slide from under the edge of the parts?


I received my OT and hookup wire I was waiting for.  I need to drill my chassis.  Strange how we are concerned about different things.  I am reusing a Power tranny with short leads I am going to have to add which is a concern and making sure all my resistors are the correct value before I solder the whole board is my largest concern.


Again, really nice work.  Thanks for joining with us and sharing your build.  In reality, that Doghouse is going to look nice and it will give you more room.  That is why I love the last chassis I made.  19 x 8 x 2.  Next ones I make are going to be 19 x 8 x 2.5 or maybe even 3". I am not sure yet, but I may have enough room to separate my power tubes allowing me to place my Power Tranny on one corner and the OT on the other.


I did score some nice Bugle Boys EL84.  Now I have 3 varieties.  I know you have JJ's, but Sluckey never mentioned what he is using.

[sluckey]

My EL84s and EF86 are JJs. All the 12A?7s are JAN Sylvanias. And the EZ81 is some off brand duck, Mallard or something.

Ed, here a pic of one possible solution for short leads on a PT...

     http://home.comcast.net/~seluckey/amps/november/nov_03.jpg

Guys, double check the under board jumpers before installing the board. I like to verify again after installing all the connecting wires. I use an ohm meter to check for zero ohms between turrets that should have a jumper. I do this from the top side of the board so I'm not actually looking at the jumpers.

[HotBluePlates]

And the EZ81 is some off brand duck, Mallard or something.

The one in the rear-view pic looks like a Telefunken.

[sluckey]

The one in the rear-view pic looks like a Telefunken.

Yep, that's right.

[Ed_Chambley]

My EL84s and EF86 are JJs. All the 12A?7s are JAN Sylvanias. And the EZ81 is some off brand duck, Mallard or something.

Ed, here a pic of one possible solution for short leads on a PT...

     http://home.comcast.net/~seluckey/amps/november/nov_03.jpg

Guys, double check the under board jumpers before installing the board. I like to verify again after installing all the connecting wires. I use an ohm meter to check for zero ohms between turrets that should have a jumper. I do this from the top side of the board so I'm not actually looking at the jumpers.

That is a good solution.  Are those sag resistors you are using?

[sluckey]

Are those sag resistors you are using?

Yes, although I rather call them dropping resistors because the voltage was too high.

[dbishopbliss]

The chassis I'm using (see reply #146) is 20 x 6.5 x 2.5. Got it from watts. I would not go any smaller.

I may go with the 20 x 8 x 2.5 chassis to give my novice building hands a little more room to work.  This would also allow me to use 4" wide board material so I could increase the distance between the turrets and use mallory capacitors instead of xicons. 


Any reason that I should not do this?

[sluckey]

I may go with the 20 x 8 x 2.5 chassis to give my novice building hands a little more room to work.  This would also allow me to use 4" wide board material so I could increase the distance between the turrets and use mallory capacitors instead of xicons. 


Any reason that I should not do this?

You can do that but it's a LOT OF WORK! I would want a more compelling reason than just so I could use M150s. As designed the board will accommodate M150s except for about a half dozen of the 0.1µF caps. M150s have been my go to cap. This is the first project I've used Xicons. Xicons will be my new go to cap.

You did notice that my drill guide is ready to print, tape to a blank board, and drill? How will you widen the board layout to 4"?

[Ed_Chambley]

The chassis I'm using (see reply #146) is 20 x 6.5 x 2.5. Got it from watts. I would not go any smaller.

I may go with the 20 x 8 x 2.5 chassis to give my novice building hands a little more room to work.  This would also allow me to use 4" wide board material so I could increase the distance between the turrets and use mallory capacitors instead of xicons. 


Any reason that I should not do this?

I used the same drill guide and had no problem using SOZO and Mallory caps.  Trick is use the 400v Mallorys.  I had Xicons as well, but I have been wanting to use up the Sozo.  Doug Hoffmans 50 watt Marshall style builds are considered some of the finest and he uses Xicon.  Xicon caps get a bad rap from people who have never used them.


We are a little cap crazy.  No one wants to use cermaic because they re too harsh, but everyone is cloning amps that have them inside them, but they make them better by knowing that Silver Mica sound better.


If you like the tone of the old amp, why use something you know is going to change it?   

[sluckey]

Hey lego... I've updated the original layout on my website. I've separated the grounds and relabeled them to match the grounding on the long board version. I've also included a ground scheme to show how it's all tied together.

The main board layout and the cap board layout both have minor changes that would require snipping a jumper on each board. Those are the only two pages that have changed. Take a look. I think you'll like it better. These changes make the grounding scheme for your amp look like the grounding scheme on my amp (except for the fact that your caps are all on a separate board).

[Ed_Chambley]

Here are a couple of photos of my board.  I will have cab photos next week.  I used larger caps than I planned to use up some I have had around.  Let me know what you think and who wants to be the first to mod this board?


You may notice I have no ground wires yet.  I am planning to build the ground scheme inside the chassis.  The ground layout is really nice..  The photo of the iron shows how short my leads are on the Power Tranny.  I believe I will be making a single row turret strip to connect.  I have found some lead I cut on a previous build and it matches.  I could simply add it.


Now its time to layout the chassis for punching and drilling.

[sluckey]

Hey, that looks familiar!

[Ed_Chambley]

Hey, that looks familiar!

Yes sir!  Layout done by one of the best and one I consider a friend.  I am just an old hack and am painting by numbers.


The caps fit better than I thought once I was working on it.  I am saving the chicklets for my next build and plan to do a Hoffman style board and they will come in handy.  I will finish this one first.
 I hope you caught up on your chores you neglected while building another silly amp.  Are you ever going to grow up?

[Ed_Chambley]

Hey, that looks familiar!

It appearss you have 3 additional drill holes and I believe I will have one.  Are these left from changing from the Doghouse version to the Long Board version?