Expression 2 has arrived (chassis pix)

[Ron]

After three days, I finished my version of the Express, which I call an Expression 2. It has some changes, including a star ground, a 10KL mid pot, and a more reasonably sized 1K/5W resistor. At this point I have 50pf and 100pf bright caps installed as I think they are more useful to my guitars and playing. Metal-film resistors were used throughout the preamp to keep the potential thermal noises low. I am very particular about using the best hardware I have. Dana's perf board lent itself well to securing and routing the hookup wire. BTW, I believe filament wiring and leprechauns should both be green. Here are some pix - I'll add a King Amplifier badge when I find where I put them:

[IMG:640:480]http://img.photobucket.com/albums/v128/ ... G_0034.jpg[/img]

[IMG:640:480]http://img.photobucket.com/albums/v128/ ... G_0029.jpg[/img]

[IMG:640:480]http://img.photobucket.com/albums/v128/ ... G_0032.jpg[/img]

[IMG:640:480]http://img.photobucket.com/albums/v128/ ... G_0031.jpg[/img]

[IMG:640:480]http://img.photobucket.com/albums/v128/ ... G_0030.jpg[/img]

[rockstah]

nice job man! - what did u use to sercure the filter caps?

[Ron]

Silicone sealer! You just can't see it. The smaller 20uf caps must go on the bottom, otherwise the larger 40uf won't fit the space because of the transformer mounting screws.

[UR12]

Ron

Looks great! You got us all waiting.......so hows she sound?

BTW I thought you said this was going to be a winter project

[rockstah]

Silicone sealer! You just can't see it.

thanks Ron - im trying to figure outw hat i need so i can go out and buy it today. any particular type of silicone?

[UR12]

Silicone sealer! You just can't see it.

thanks Ron - im trying to figure outw hat i need so i can go out and buy it today. any particular type of silicone?

You can also use a hot glue gun but it can get messy and you have to be quick to set the caps before it cools off. The silicone works great.

[rockstah]

Silicone sealer! You just can't see it.

thanks Ron - im trying to figure outw hat i need so i can go out and buy it today. any particular type of silicone?

You can also use a hot glue gun but it can get messy and you have to be quick to set the caps before it cools off. The silicone works great.

so silicone sounds easier - but what kind? - i have never purchased silicone before and dont know what im looking for.

[Ron]

Silicone sealer! You just can't see it.

thanks Ron - im trying to figure outw hat i need so i can go out and buy it today. any particular type of silicone?

I used GE Silicone II Window and Door sealant. No drafts inside the amp now.

While I haven't spent alot of time playing with it yet (just finished at 11 pm last nite), I think it sounds like it should. I had a problem with a ground loop from the EQ area. It turns out I was too smart about the star ground and had to remove the lead between the buss bar and the star point. Instead, I grounded the buss bar to a ground lug under the mid pot and the hum disappeared. There is a little hiss, but it's a high-gain amp and I am pleased with how little there is.

It sings and cleans up well for blues. This would be a more versatile amp if there were a clean Fender channel as well. Take an AB165 Bassman head and make an Express clone in the Deep channel (it has two 12AX7s available), change over to EL34s, and you will have it. I did this a couple years ago and offered it as the Expression mod.

Dana, winter came early this year. I saw that I had all the major parts so I went for it!!

[rockstah]

Silicone sealer! You just can't see it.

thanks Ron - im trying to figure outw hat i need so i can go out and buy it today. any particular type of silicone?

I used GE Silicone II Window and Door sealant. No drafts inside the amp now.

While I haven't spent alot of time playing with it yet (just finished at 11 pm last nite), I think it sounds like it should. I had a problem with a ground loop from the EQ area. It turns out I was too smart about the star ground and had to remove the lead between the buss bar and the star point. Instead, I grounded the buss bar to a ground lug under the mid pot and the hum disappeared. There is a little hiss, but it's a high-grain amp and I am pleased with how little there is.

It sings and cleans up well for blues. This would be a more versatile amp if there were a clean Fender channel as well. Take an AB165 Bassman head and make an Express clone in the Deep channel (it has two 12AX7s available), change over to EL34s, and you will have it. I did this a couple years ago and offered it as the Expression mod.

Dana, winter came early this year. I saw that I had all the major parts so I went for it!!

thanks man - ill see if they have that at home depot - again, beautiful job on the amp!

Mark

[rockstah]

i noticed you put the 20u's on the chassis and the 40u's above them - its to make them fit better or?

[Ron]

i noticed you put the 20u's on the chassis and the 40u's above them - its to make them fit better or?

Yep, exactly. I described the reason in a previous post above.

[rockstah]

i noticed you put the 20u's on the chassis and the 40u's above them - its to make them fit better or?

Yep, exactly. I described the reason in a previous post above.

thanks - i missed it in the provious post.

[rockstah]

hey Ron,
how long did you have to let it dry? and will it really hold the caps in place good?

Mark

[tubedogsmith]

Ron, I know this isn't your first rodeo. Do you have any trouble with notes dying fast with it cranked? Have you scoped it by any chance? Running the presence wire through the filament wires and having the grid wires in proximity to all that just never worked right for me. Maybe I need more patience.

[Ron]

hey Ron,
how long did you have to let it dry? and will it really hold the caps in place good?

Mark

It doesn't really dry, it's a chemical reaction with air that releases a vinegary odor. The outside of the silicone will cure first, but the interior could still be squishy. It takes a couple hours to get enough strength to work with the parts. Do it in three steps:

1. "Glue" the three 40uf caps together with silicone, after soldering their ground leads together. You can put a piece of tape on one side to hold them together, then apply some silicone in the grooves between them on the opposite side. Let cure for a couple hours.

2. Lay two of the 20uf caps in the grooves formed by the three 40uf caps and see how much separation there is between the two 20uf caps (roughly 1/8"). Then solder the ground leads of two 20uf caps together while making sure the caps are separated by this distance. When done, 20uf cap will not be in a groove, so the ground lead connection with its neighbor will help hold it in place. Now, apply silicone to one groove and lay a 20uf cap in it.

Note how the 20uf caps are recessed slightly (~3/8") in my amp, behind the longer 40uf caps. They will fit between the PT front-to-back mounting screws, and the grounds of the 40uf will touch the front panel unless you recess the 20uf's slightly.

Apply silicone to the second groove and set the connected pair of 20uf caps in place. While holding them there, apply silicone to the groove between the semi-loose 20uf cap on the end and the 40uf cap below it. Use a piece of tape to hold it in the correct position if you need to. Let cure for a couple hours.

3. Apply a generous amount of silicone to the two grooves between the three 20uf caps, invert the stack and set it into place. You should dry fit it first, of course. Let cure overnight. This holds the caps very securely and it looks OKay unless you got sloppy with the silicone. It's possible to cut and scrape the excess if your German heritage demands neatness like mine did.

I hope this helps you, sorry for the excess verbage.