lego's spin on Sluckey's AC15

[lego4040]

So Neil's pedal board fails 2nd song into set and he says fuck the pedals and plug straight into the amp(ac30) vox tules

[jojokeo]

Be quiet with this comment.  There are some who will punish me.

Still playing with PtP builds and really like it.  They are really a challenge.

Don't worry, nobody will find out your secret. 

Here's the EF86 channel AC15-ish chassis amp going waaaay back in the day that still sit's on a shelf & gets dusted off every once in a while to remind me how far things have come, it's a hybrid sort of P2P does that count? Actually I have others but again don't want to stray from the AC15 topic. This can be an example of how small & simple one can be made and without tone knobs too. But it does have a gain switch and pentode/triode mode for both ef86 and the EL84s.

[jojokeo]

So Neil's pedal board fails 2nd song into set and he says fuck the pedals and plug straight into the amp(ac30) vox tules

lego - now I want to hear what came of it!?

[lego4040]

The sound was incredible. You don't need pedals except for the modulated stuff. He is a family oriented person, his wif is the bassist and for second encore he brought out Liam and Elroy jus sons and ripped on Bowies Moonlight Daydream, not since Racer X  gave I heard a fantastic version

[sluckey]

Does this resemble the Vox faceplate?

EDIT... big pic removed.

[sluckey]

Quick question, is your context spell correction working on the new forum.  Mine is not.

Yes. Your spell checker for your face plate software is not working either.   

Mine is reverse of yours.  Is mine backwards?

yes

[sluckey]

That looks good Ed. I would put the ON label above the power switch though. And I like to label the standby switch with "OPERATE" above and "STANDBY" below.

[lego4040]

So when can I order one, seriously.

[SILVERGUN]

Man, you guys are having too much fun over here....I'm enjoying reading along

I love to see tube fever running rampant 

This will make a very good build guide for the future, covering every detail.

Keep up the good work lego and keep inspiring the "regulars"

[sluckey]

Don't understand.  Standby=No Dc, Correct.  Marshall switches go down for contact and up to break contact.  I like the term operate, so shouldn't operate be on the bottom replacing ON?
 
Also, if you would, please address the jumping.  If I can put a switch I would love to remove the low jacks.

The switch don't care. If you want to play guitar when the switch is up, put "OPERATE" above the switch. If you want to play guitar when the switch is down, put "OPERATE" below the switch and simply rotate the switch body 180°. In my mind it makes more sense to flip both switches up to be on and operating.

You can use a switch to jump the channels. Here's another option... Just use a single input jack and a three position switch to select either channel or both channels. Might look like this...

EDIT... big pic removed.

[sluckey]

If you install them upside down they are about 3/16 from the chassis.  Maybe even a tad closer.  I am scared this is too close.  Do you agree?

I would not be concerned about 3/16" clearance. Put a piece of electrical tape (or other insulating material) on the chassis near the contacts if it makes you feel safer. This is done all the time.

I really want to do the front switching and I know you know how or you would have not mentioned it.  I just cannot get my head around it.  Is it on-on-on DPDT with the input to the center.

Yes. It's a DPDT on-on-on. Connect the jack to both center terminals. Connect one end terminal to NOR tube. Connect the opposite end terminal for the adjacent switch to the VIB tube. It may be difficult to find a toggle switch that matches your Carling switches though.

Maybe a better solution would be to use this 3 pole 3 position rotary switch from AES...

     http://www.tubesandmore.com/products/P-H395

[dbishopbliss]

I have a friend that REALLY wants an AC-15 so I'm pricing it out for him.  The only 22K 7W resistor I can find on mouser must be purchased in quantities of 100 or more.  Does someone have another source for these?

[sluckey]

That 22K 7W spec came from a parts list that I got from Bnwitt. The power spec is unconfirmed. I'm just using a 22K 3W metal oxide available from Hoffman for now. I plan to measure the actual dissipation as soon as the amp is built. The 3 watter may just be enough. If not, my plan is to use two each 47K 3W in parallel.

BTW, my long board layout is designed to accept the 3 watt metal oxide resistors. Using another form factor might not fit very well without board modifications. If you use the separate cap board you have room for almost any form factor for 10 watters or less.

[dbishopbliss]

I'm not ordering right now just giving ballpark cost but I am trying to put together a BOM to make ordering the parts easier in the future.

What are the dimensions of chassis people are using?

[sluckey]

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.

[jojokeo]

I do however have an amp room, or closet.  Whatever you want to call it and it is almost soundproof.  I control volume by how far I open the door.

There is only my wife and dogs at my house and neither care as they hear it every day.  I guess I am lucky as many wives do not like loud guitar.  Mine doesn't either, but she lives with it and I live with Dance Moms and a million bottles and brushes in the bathroom.   I believe after 40 in men a new gene appears and I call it the apathetic gene.

You know the difference between ignorance and apathy?
I don't know and I don't care.   I have had waaaaaaaaaaaaaaaaaaaayyyyyyyyyyyyyyyyyyyyyy to much coffee.  I will quit now.

I was just trying to catch-up on this by reading the entire thing but it's very challenging to say the least as the new posts keep popping like Jiffy Pop popcorn.
 
Ed, that's some funny stuff there and nothing closer to the truth for me too! You know the things that are funniest are the things that are closest to reality in real life situations. A good comic knows this and Ed my friend, I think you may be missing your true calling???!!! 

[sluckey]

Ed, I noticed the pilot light is not in line with the other controls. Is that planned?

[lego4040]

Ed that's perfect , I'm using ken watts 20" x6.5 x 2.5 chassis.my tubes came in also. Is that the color or what you put on with the program

[lego4040]

I will look at a head I was interested in for the face measurement. 100 hours of break in I thought a bout using Jupiter Reds for the Vibrolux

[lego4040]

What ever size 17" and longer is great Ed, I'll probably have cab made and give them the size needed

[sluckey]

I got the front panel drilled and loaded today. Even got a poor man's face plate on it. Beginning to look more like an amp now.

EDIT... big pic removed.

[sluckey]

The faceplate is inkjet photo paper stuck to the chassis with double sided carpet tape.    I rather have one of your fancy plates but I would require 20" long.

All four toggle switches are short bat Carling SPST (like Doug sells).

[lego4040]

  I need to hit lotto so I can just work on this all day. I couldn't get my head wrapped around your DPDT theory, can someone draw it out? I'm working on 4hrs sleep out of the last 48. Last nights  and  wearing me down right now

[lego4040]

Been reading your reply Sluckey on the one input way for switching between normal and vib. I get on-on-on but why dpdt not spdt if your signal is going to center and the two other legs are either nor/vib. My other question is since it's only one input each channel are you using high or low? I'm sure  with another switch you can put that on back of chassis and have that option still.

[sluckey]

I get on-on-on but why dpdt not spdt

I've never seen a single pole three position switch where the center position made contact with both outer lugs (ON-ON-ON). The usual configuration is the center position makes contact with no other lugs (ON-OFF-ON). I suppose someone may make such a switch.

However, ON-ON-ON configuration is commonly available in double pole switches. Look at switch 7211 in this C&K spec sheet (page 2). Imagine pins 2 and 5 tied together and connected to the input jack. Now connect pin 3 to CH 1 and pin 4 to CH 2. This wiring will give you CH1, both, CH2.

     http://www.mouser.com/ds/2/60/7000Toggle_20feb14-241455.pdf

My other question is since it's only one input each channel are you using high or low?

It's high. The low input is just a voltage divider sample (lower level) of the high input.

[lego4040]

  thank you Sluckey. Not like I haven't used these in pedal builds, I just blank with the amp build because of size a lack of experience.

[sluckey]

Here's an easy board mod for those who like to check bias. Just add two turrets and two 1Ω resistors. The big 130Ω/10W will need to be replaced with a 130Ω/5W. See pic...

EDIT... big pic removed.

[HotBluePlates]

I get on-on-on but why dpdt not spdt

I've never seen a single pole three position switch where the center position made contact with both outer lugs (ON-ON-ON). The usual configuration is the center position makes contact with no other lugs (ON-OFF-ON). I suppose someone may make such a switch.

You get single-pole On-On-On in a rotary switch. It takes 4 contacts; 3 switched circuits and a common.


Like you said, maybe someone out there makes one, but I've not seen it in a toggle switch. You'd probably only need to buy a couple hundred-thousand to have a company custom-make them. 

[lego4040]

That bias mod is easy enough to do. I drew your switch out and I get it, I had my number to pins wrong when I first drew it out. But with the two lows gone now and only one line going into switch legs 2&5 what is the wiring layout for the two jacks. I know you need the 68k for them but not sure on the rest

[lego4040]

I'm going to try and answer my question    does this look right? Or do I loose that 1M or am I way off

[sluckey]

does this look right?

yes

[lego4040]

  It takes a while but sometimes the mind works right. Thanks for the patience

[sluckey]

does this look right?

yes

There is one thing I forgot to mention... You need to remove the 1MΩ from the hi jack. Now install two 1MΩ resistors on the switch. One connects to pin 3 and gnd, the other connects to pin 4 and gnd. This way both tubes always have a grid return to ground regardless of the switch position.

[sluckey]

Looks like I'm backing up but I'm really still in forward gear. All chassis drilling is completed and heavy stuff removed to facilitate some wiring such as filament string and board interconnects. But I've got to break away for a few days and take care of some yard and garden chores. Come on rain!

EDIT... big pic removed.

[lego4040]

   I made the schematic change for the switch, thank you. I finally heard back about chassis and parts, and of coarse they were slow getting shipment out and I'll be away when it gets to my house  Post office better not loose it. I got to call my buddy and see if the Iron got in yesterday too

[lego4040]

That is beautiful

[Willabe]

Did it come with that shield around the IC connector?  Why is that needed as it seems it would create more problems.

Look closely at the schematic on it.

There's a little circuit inside to kill incoming line noise. There's different types for different equipment and different dB loss at different frequencies? A few R's, a few C's and maybe a small inductor or 2.

Look up Corcom inlet filters at Mouser. I can't seem to capture the link. There's differential, common mode and combinations of the 2. Can't explain any more as this is above my pay bracket. 


             Brad      

[Willabe]

Is sort of a line conditioner?

Yes. It kills line noise hash before it can get into the PT primary.

Go back and look at my post as I added text while you were posting.

I would bet that most guys here would say it's over kill but with more and more electronic gadgets coming on the AC power grid and more and more loading of the AC grid with sudden spikes of use there's more and more noise coming on line with it.


             Brad     

[Ed_Chambley]

I use them all the time, just did not know what they were,  I got it now.  The ones I rob from power supplies are made this way.  Mine just look different.


Thanks!!!

[Willabe]

There called power entry modules in the Mouser catalog for EMI and RF.

I would think at this point most if not all computers come with these stock as there not much money anymore because of mass production?

Medical equipment uses special types so no one who's hooked up to a machine gets messed up because of interference coming in from the wall acv. Those seem to cost a lot more but if it saves a life fine. We don't need as much protection as they do just for our amps to knock down some line noise.


             Brad     

   

[lego4040]

I got a few donor pc's for those receptacles, On pedal builds we usually just add a 100ohm resistor(dont hold me to that value) in series with the hot side coming in. I got my board soldered, both sides. And after close look I had one leg wrong on the underboard wiring. I fixed it and Im in limbo while other parts come What do you guys use to get rid of the flux specs? I will remember next time to solder jumpers before populating. I knicked one Mallory with solder gun   Not bad but I was doing real good until that

[sluckey]

Couple of questions about your chassis.  Did it come with that shield around the IC connector?

My chassis came as a completely undrilled empty blank box. The IEC connector has a built in EMI line filter. I used it only because I had it and I didn't have a plain Jane IEC connector. Certainly not necessary.

Also, did you tap the holes or did it come that way.  I have never felt confident with bolting into aluminum.  Do the holes hold up well, or is there a nut in the other side I cannot see?

I tapped the tube socket screw holes with a 4-40 bit. The cap can is tapped for 6-32. This is a thick chassis. Light weight stuff like the sockets are very secure. All iron is bolted on using 10-32 screws and kep nuts.

[sluckey]

What do you guys use to get rid of the flux specs?

Mineral spirits works well. I also have an aerosol can of flux remover that works well. I think Doug once said he allows the flecks to harden somewhat then just uses some pointy object to just flick them off.

[dbishopbliss]

Looking through the parts bin today... I have a hammond 270FX power transformer already - I don't even remember what I bought it for.  I also have two triad chokes; C-7X 10H, 90mA, 270 ohms and a C-14X 6H, 200mA, 150 ohms.  Could I use either of those chokes?


Also, in another thread there was a question about the best output transformer for this amp but it doesn't seem like there was any real consensus.

[sluckey]

I would use that C-7X if I already had one. This amp is probably gonna idle at about 70mA and all that current will be flowing thru the choke.

I'm using the Hammond 1650F OT mainly because I salvaged it from my Lightning amp. It's a good match for a PP pair of EL84s and the Lightning power amp is almost identical to the AC-15 circuit. If I had to buy new iron it would be a coin toss decision between the Hammond iron and the ClassicTone set for the AC-15. I decided against Mercury Mag solely because of price.
 

[Ed_Chambley]

I could find no consensus on a transformer set.  I did a lot of searching, emailing and speaking with people.  I did not find anyone who actually used the Classictone as they all have the same question.  6K primary on it, but Mojotone has one with a 6K primary and they are sold out.  People must be using them, but I wonder if they are using then on the newer ones as I have heard they are having a lot of transformer problems.


  I decide this way.  If I am experimenting with a build, or if I have a strict budget for the build I look for one with the specs I need and go for it.  I usually will have one I have puled from something else.  One common characteristic of all of the replacements as they are beefy, much more so than say a Princeton.


If I am building an amp for me that I want for a keeper, you know, like I am building a cabined and getting the exact speaker I want I ask myself what I would use if it were free.  Then I begin to try to find the best price for that.  The reason is by this time I have already spent so much time, effort and money that another $50 is chump change at this point.  Hell, I spend 4 and a half hours just looking at the physical sizes of caps to choose the ones I wanted, but this amp is for me and will be a keeper.


I really like Hammond Iron, the stuff from Canada that Logo and Sluckey are using.  I would not use the Classictone simply because of the 6K primary and I could not get any response form Magnetic Components.  Mojo just told me it dod not matter and I got pissy and told them to just send me one for a JTM45 then.  Edcor has one that looks right and is least expensive of all.  it is this one:
https://www.edcorusa.com/cxpp21-ms-8_6k
I bought one of these also as I wanted to see how well it sounds against the Mercury I ordered.  The specifications look great and is multitap.  Looks better to me than the Classictone and almost half the price of the Hammond.


The largest consideration on the Hammond is they make great Transformers and Keep in mind that is what Sluckey is using and I assure you it is not just because he salvaged it from the spitfire.  From what I have noticed is if he felt it was not a great choice he would not be using it as I see a lot of Mercury iron in his other builds.


I know this was long and I hope it helped.  The Edcor is great stuff and if I were contract building one (which I think you are doing), it is what I would use for Power, Choke and Output.  I could make a tad more money and not feel bad at all.  They look great and when I have used them for builds the client feels they are an upgrade since most of us are used to seeing silver and black end bells.

[dbishopbliss]

The Edcor is great stuff and if I were contract building one (which I think you are doing), it is what I would use for Power, Choke and Output.  I could make a tad more money and not feel bad at all.  They look great and when I have used them for builds the client feels they are an upgrade since most of us are used to seeing silver and black end bells.

I wouldn't say I was "contract building" an amp.  My friend knows I build stuff and he really wants an AC15 so this thread caught my eye.  I am putting together a breadboard version of my 1 watt amp to build and while I was digging out the parts I noticed I had quite a few parts that work for this project.  When I was younger and had more disposable income, I would buy stuff thinking I would build but usually never got around to it.  Now I'm trying to use what I have.

By the way, the edcor transformer you linked to is 8.6K while the Hammond that Steve suggests is 7.6K.  Did you mean to link to the edcor CXPP25-MS-7.6K?
I've heard good things about ClassicTone in general so I wonder why they don't make a transformer that is closer to the AC15 spec.

[sluckey]

ClassicTone's claim states " Vox AC15** Style Amplifiers ".

[Ed_Chambley]

The Edcor is great stuff and if I were contract building one (which I think you are doing), it is what I would use for Power, Choke and Output.  I could make a tad more money and not feel bad at all.  They look great and when I have used them for builds the client feels they are an upgrade since most of us are used to seeing silver and black end bells.

I wouldn't say I was "contract building" an amp.  My friend knows I build stuff and he really wants an AC15 so this thread caught my eye.  I am putting together a breadboard version of my 1 watt amp to build and while I was digging out the parts I noticed I had quite a few parts that work for this project.  When I was younger and had more disposable income, I would buy stuff thinking I would build but usually never got around to it.  Now I'm trying to use what I have.

By the way, the edcor transformer you linked to is 8.6K while the Hammond that Steve suggests is 7.6K.  Did you mean to link to the edcor CXPP25-MS-7.6K?
I've heard good things about ClassicTone in general so I wonder why they don't make a transformer that is closer to the AC15 spec.

I did not intend to link to the one you linked to.  The one you linked to will work as well IMO.  I just ordered the other one because it's primary is over 8k and some of the older OT's speck for EL84's were upwards to 10k on the primary side.  Hammond has been making transformers a long time and I have never had a problem with them.  They are bulletproof, for the lack of a better term.


I ordered it because of the power wattage being less.  I have another 10K pull from a Bladwin organ.  This one falls sort of of in the middle and will give ma many alternatices for tewaking. I can sell any OT I have pretty quickly if it can be used for Push Pull 6v6 or EL84.  I do collect too many parts and completely understand as I have stuff I am sure will never be built.  I also have radio parts like this.  I am not under the delusion "i will build this or that one day".


Like any other hobby I have, I usually go overboard.    I did not mean anything about the contract comment other than building for someone else.


I am wanting to recreate an amp sound I have in my head from 33 years ago and I know it is different than I remember.  It is just one of my crazy things I do.  I was simply suggesting the Edcor as a less expensive alternative instead on the Classistone as I am absolutely sure I would not use their AC15 Style OT as Sluckey put is, however in the early years Vox did use a 6k3 primary.  If you build it as the layout and use a proper speaker, it will sound like an old vox whether you use Hammond, Mercury or Edcor I believe.


I think we may be splitting hairs here.  The only reason I am not using the Hammond is because we have 2 others *Logo 4040 and Sluckey* using the hammond.  Also, there is no denying Mercury makes great stuff, but the do put a little snake oil on everything the sell.


There are other great amp builders, most much better than me.   IMO, you it would be best to listen those who have a more knowledgeable electronics background.


I have never heard anyone mention anything negative about Edcor and I really like it for a less expensive alternative.

[dbishopbliss]

ClassicTone's claim states " Vox AC15** Style Amplifiers ".

So does that mean they overheat and fail. 


I have't compared, but I expect that there would be a difference in sound between a 6K, 7.6K and 8.6K transformers.  What did VOX use, or is it all of the above since they seemed to change manufacturers (Pameko, Woden, Haddon)?  I might have to buy a ClassicTone and have my friend by an Edcor so we can compare.