18w project

[jay_back_in_chicago]

Hey everyone, here I come with my latest build plan.

I have made few amp tweaks so far, mostly to my valve jr. and my ceriatone twreck clone and now I'm moving on to first build.

Got myself a set of classic tone 18w marshall transformers, and I'm going to build Lite 2B version with 6v6 in it, and from mhuss website I will experiment with supro tonestack, I wonder how it sounds.

What would be best layout out there for Lite 2B? What changes will I have to make for 6v6?
And after all, I found few BOM's online, is there anything in particular that I should follow? For caps and resistors that is, I have all the other parts ready.

[sluckey]

Here's my Dual Lite. It's a Lite IIB plus a Vox AC-15 Lite in one small chassis. The schematic and layout are at the bottom of the page...

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

You may find a dedicated Lite IIB layout on the 18watt.com forum or else where on the net. Use google. I don't recall seeing a layout on this forum.

As for BOM, do your own from the schematic you choose. That's an excellent way to become familiar with the amp circuit.

Here's a schematic that includes notes for using 6V6s as well as EL84s...

[jay_back_in_chicago]

what a nice build!

yes, saw that one, found layout that was so far my reference point.

One question, since I have GZ34 and 5v4 both at home, will there be much difference since the amp is cathode biased?

[sluckey]

One question, since I have GZ34 and 5v4 both at home, will there be much difference since the amp is cathode biased?

no

[jay_back_in_chicago]

so I will go with that...

few more... i have already 32uF + 32uF 500V at home, F&T, could I use that instead of 33uF 450V x2 in schematics you posted?

[sluckey]

yes

[jay_back_in_chicago]

So I made my own BOM for the build, caps and resistors, and I will leave it here so if I made a mistake somebody can point it out, and if it's correct it might be of use to somebody

CAPACITORS (total number=13)

2x  50uF  50V
1x 0.0047 uF
4x 10nF
1x 100nF
1x 470pF Silver Mica

1x 16uF 450V
1x 32uF + 32uF 500V Radial

RESISTORS (total number= 21 )
1M    x2
820  x2
120K
22K
470K x4
100K  x2
8.2K x2
1K 3W
250 5W
100 3W  x2
2K2 2W
8K2 2W
220K 1W


POTS
500K LOG (audio)  x2

[sluckey]

Which schematic?

[jay_back_in_chicago]

Following the one made by mhuss (link bellow) and the one you posted I used for 6v6 mods.

http://mhuss.com/18watt/schematics/18wattLite2b.gif

[jay_back_in_chicago]

Pretty much everything is ordered, I just had hard time finding 5W 250 resistor here in EU, any advice?

[kagliostro]

If you want to share a BOM seems mandatory to post a schematic that corresponds exactly

Franco

[jay_back_in_chicago]

If you want to share a BOM seems mandatory to post a schematic that corresponds exactly

Franco

Working on it as we speak, it's just a few changes but I will scan and post when done

[sluckey]

I would use this...

http://www.tubeampdoctor.com/en/shop_Resistors_Wirewound_Resistors/Resistor_270_Ohm_5W_5_for_Fender_Tweed_Deluxe_1507

[jay_back_in_chicago]

thank you, I will wait for it to become available

for all the resistors I went with carbon comp 1/2 W, unless more is specified, is that ok?

[sluckey]

I'm sure if you use google you can find plenty of EU suppliers. Here's another supplier...

http://www.ampmaker.com/store/5W-metal-oxide-power-resistors.html

[jay_back_in_chicago]

There are, TAD is just practical since I buy there often, have some discount and local free shipping....thank you for the tip anyway

[kagliostro]

If you buy also from RS

http://it.rs-online.com/web/p/resistori-montaggio-a-foro-passante/8916287/

http://it.rs-online.com/web/p/resistori-montaggio-a-foro-passante/8915830/

http://it.rs-online.com/web/p/resistori-montaggio-a-foro-passante/8506604/

Franco

[jay_back_in_chicago]

All the parts are here, and I started...

Here is assembled board with extra lugs so I can mod it to use cap can 32 + 32 and still connect it according to dockery layout.

One question...If I decide to use one switch, so off-standby-on, what should I buy?

[sluckey]

One question...If I decide to use one switch, so off-standby-on, what should I buy?

Click the "switches" link at the bottom of this page. Scroll down until you come to this switch...

Carling DPST Switch
3 Position toggle switch
You can use this switch for Off-Standby-Play
Very nice if you only have one switch hole
4 Solder terminals
Click here for wiring information.
 Price each = $7.35

[jay_back_in_chicago]

Will order that one soon!

One dumb question, but I want to make sure. Can I use terminal strip for 2x 3,15 and ground? And then wire from there according to schematic?

[sluckey]

Can I use terminal strip for 2x 3,15 and ground? And then wire from there according to schematic?

Sure. Lot's of people do that, including me sometimes.

[jay_back_in_chicago]

Ok,I can finish planning my layout then, attached is my plan now...

My 5v 2A and 0 wires are really tough, I will just run them parallel to rectifier, there is no way I could twist them. Same with heaters, I will run them parallel to terminal and twist from there. Is that ok?

What about 6.3V unused wire for rectifier? I just shorter it and tuck in somewhere ?

[John]

Twisting from term strip will be fine. IMO though, the routing of the heater wires is way more important than whether they're twisted or not. I have started positioning my tube sockets so that the heater wires are always away from everything else (usually along the back side of the chassis). And I don't bother twisting anymore. But, Best Practice is indeed, nice neatly twisted heater wires. 


The 6.3 unused wire you're talking about; I wouldn't shorten it any, but just coil it up nice and neat and tuck it out of the way. You never know what you might use this transformer in at some point down the road. I've used the same set in 3 different builds.

[sluckey]

What about 6.3V unused wire for rectifier?

Be sure to put tape or heat shrink tubing on the end. That wire will have B+ voltage on it.

[jay_back_in_chicago]

Will do so, heat shrink it at the end and tuck away.

I was planing to run heaters in end corner, as far away from everything else.

Is my preamp tube placement ok? I wanted to give more space to myself back there so I moved them up front, plus I will need shorter wires for V1 and V2 to connect them to jacks.

[jay_back_in_chicago]

I have some shielded wire leftover from old hiwatt clone that I got so many years ago, pic attached under

Is that enough AWG for this amp or am I better buying new wire?

Since there is no ground connection on other side for that wire, is there alternative wiring that I could use? like from jack ground to chassis?

[shooter]

Since there is no ground connection on other side for that wire,

It's fine for your input, you only ground 1 end, just like your layout pic shows.  The "tube" end only connect the signal wire, NOT shield.

[jay_back_in_chicago]

I get it, will just re use those wires in this build

[Ritchie200]

"jay back in Chicago" is in the EU?  Is there a story behind this?

Jim

[sluckey]

Yes. I want to hear it too! 

[jay_back_in_chicago]

"jay back in Chicago" is in the EU?  Is there a story behind this?

Jim

sure thing!!! not so interesting haha 

I have been traveling a lot for work last few years, and so many good things used to happen right in Chicago, that after a while I began to say to all my USA( and other) friends, "When I come back to Chicago(instead of USA), it will..." :D

Now I use any opportunity I have to visit ;), and  If I expand my business enough I will open an USA branch right there, or Oregon

[moonbird]

Sorry for the intrusion    Jay.


Sluckey - What would be required to add a little "plexi" dust to this already very cool design? Could some mix resistors be added before the PI to allow both channels to be active?? If so, could you suggest some mods to try - I would have no idea what components would allow this idea to work. Thanks kindly.

[sluckey]

Build this instead...

http://www.ax84.com/index.php/oldprojects.html?project_id=november

[moonbird]

Yayyah - Way cool Sluckey. Thanks.

[kagliostro]

http://sluckeyamps.com/november/november.pdf

http://sluckeyamps.com/november/november.htm

Franco

[sluckey]

Sluckey - What would be required to add a little "plexi" dust to this already very cool design? Could some mix resistors be added before the PI to allow both channels to be active?? If so, could you suggest some mods to try - I would have no idea what components would allow this idea to work. Thanks kindly.

I was not trying to be a smartass with my answer. There's just no way to get from the amp Jay is building to what you're asking. Jay's amp is an 18 watt Lite IIB. It is based on the Marshall 1974 circuit, but the normal channel has been removed and the tremolo circuit has also been removed. This leaves a single preamp feeding into a cathode biased EL84 power amp. There are no two channels. This amp is so different from a Plexi that I suggested you just build an amp that is based on the Plexi design.

Now here's the smartass answer. Please take it in jest...

If you want 'to add a little "plexi" dust to this already very cool design' then put a plastic faceplate on it.   

[shooter]

put a plastic faceplate on it

I used art glass, doesn't sound plexi, but then I don't sound like a guitar player

[moonbird]

Sluckey - No worries. As a hijacker I get what I get I figger. And yes I appreciate the jesting!!


Just for the record however, I was talking about your dual British amp. I though having a plexi-style, mixed input; might be fun and make it a sort of "triple" British amp. Thats what I thought of when I saw your schematic. Needs another thread I reckon.


Cool blue shooter!!

[sluckey]

Just for the record however, I was talking about your dual British amp.

Ahh! That makes a big difference. But you never mentioned that until now.

If you want to do that then drop the input selector switch and tie the two inputs together. Then tie the two preamp outputs together using 220K mixing resistors and feed that to the top PI input cap. Ground the bottom PI input cap. Use the two volume controls to blend the two channels together as desired. Expect a bit of interaction.

I actually considered this when I built the amp but ultimately decided to go with the existing circuit just because I was not interested in blending the two channels together. I wanted one or the other, not both.

[moonbird]

Sluckey - Sorry to all for my inept communications earlier. Perfect!! Just what I was looking for!! Many thanks!!


Jay - Best of luck on *your* project!

[jay_back_in_chicago]

no problem on asking for informations here! It's all in good spirit if you ask me

My chassis will be done tomorrow, and I will  continue with my project. I used this weekend to finish head box finally

[jay_back_in_chicago]

Guys, I used silver unprotected wire for ground connections under board, is this ok?

[jay_back_in_chicago]

I need rectifier advice/help

I'm using gz34

pins 4 & 6 are for 290V connections
pin 1 goes to my standby switch

but with heaters, pin 2 and 8, next to 8 stands f,k,....my question is, out of 0V and 5V, wich ones goes to pin 2 and which to pin 8?

thanks

[sluckey]

Pins 4 and 6 are for 290VAC connections.

Pin 1 is not used.

Pin 2 goes to 0V on the filament winding.

Pin 8 goes to 5V on the filament winding. Also connect a wire to pin 8 that goes to the standby switch.

[sluckey]

Guys, I used silver unprotected wire for ground connections under board, is this ok?

I would use insulated jumpers. I would also redo those jumpers to look like this...

[jay_back_in_chicago]

thank you for grounding tips, will do that

about gz34,glad I asked, all the pin outs suggested I need to use pin 1 :(

[sluckey]

about gz34,glad I asked, all the pin outs suggested I need to use pin 1 :(

Really! I've never seen a datasheet that said to connect pin 1 to anything. Can you post a link to a datasheet that says to use it? Especially a datasheet that suggests to connect pin 1 to a standby switch.

[jay_back_in_chicago]

maybe that was my misunderstanding of data, or trying to combine ez81 logic with gz34 logic :/

[sluckey]

.

[jay_back_in_chicago]

Now I understand it, tahnks

This is how I wired my 32+32 uf cap

(I know that resistor looks really close to the screw but there is good amount of distance there)

Is this ok??