Building a new Express check the pix !

[martin manning]

You can use single conductor wire, but you should twist the pairs together (coupling caps to pots is one pair, pot wipers to power tube grids is the other). If you use 2-conductor shielded you can use the shield to carry the bias voltage and have just two cables.

[Curranproducer]

LOVE THAT PPIMV!!!!!! so sweet!!1 it doesn't do a darn thing to the tone!!! if anything it makes the amp more metal!!!!!

[Curranproducer]

I failed to twist the wires for this monster but it still sound incredible!!!!

[martin manning]

I failed to twist the wires for this monster but it still sound incredible!!!!

The twisting is to provide some self-shielding to prevent oscillation. If you are not getting any, then it's all good.

[Curranproducer]

OK!!! i am super in love with this amp!!! tons of gain and incredible tone!!!! I still have an issue with the amp oscillating when nothing is plugged in AND the volume/treble/MV are pegged. I got the 33K grid stopper happening, and the 1M across the input jack. The amp is actually louder and noisey with nothing plugged into it as well. There is a lot of SHHHHHHHHHHHHHHHH before I plug anything into it. When I plug in the guitar it quiets down NICELY!! It is almost creepy how quiet the amp is for how much metallica distortion is coming out of it. This thing is quieter than my Dual rec and MKIV with the same level of saturation!


the next question, how can I get the tone stack to be more "re-active". I am not unhappy with the tone by any means, BUT I would like to know how to make the mids scoop harder, and the bass to get more aggressive in the amp. It seems to me that all the boutique amps I amp building have more "passive" or "transparent" tone control reaction. With the mids turned all the way down there is still a ton of midrange. But on my dual rec, or JSX I can really scoop out that midrange. I know the JSX has an active tone stack but i am not sure about marshall's and boogies.

I am going to build another TW but go for a two channel thing with a vox clean then a straight TW gain channel. but I want to make the EQ on the TW side of things really aggressive in its ability to effect the tone

[martin manning]

For more scoop, make the tone stack more Fender-like: 250p treble cap C2, 0.1u bass cap C3, 250k treble pot.

[Curranproducer]

would there be a way to make that switchable on the front of the amp? I will try goofing with that anyway on the turret board

[martin manning]

It might be difficult to switch all that without running into noise and stability problems. You can see what the effect is with little effort by changing the treble cap to a 250p, and then just tack an 0.068u (or even an 0.1u) across the bass cap, and a 330k resistor across the treble pot's outer lugs to make it look like a 250k.

[jjman]

The input jack may have a poor connection between it's shorting contacts.

[Curranproducer]

hmmmmmmmmmmm I may have to check that out. I have a bunch of input jacks from a recent order and my 18 watter is still acting incorrect. like it is a crummy connection or somthing?!?!? i will have to swap and see what happens

[martin manning]

I think jjman is on it. Try shorting the tip of the input to ground, or maybe just push on the contacts with a chopstick and see if that quiets it down. You might the able to adjust the contacts and get it to work.

[Curranproducer]

OK, SO i have been working with this beast for a few weeks, and most of the overlords here know that the amp is kinda noisy when nothing is plugged in. I Did find that one of the can cap grounds had broken loose at some point. I regrounded the cap, but still the same thing. I sand papered the input jack connections and I think that cleaned up the oscillations. I pegged all the controls, and no whistling. BUT if I slap the chassis I get lots of the noise coming though the amp in addition to the general noise of the amp with nothing plugged in. I have the Kevin O'connor book that show decoupling each preamp stage can reduce the noise dramatically without affecting the tone. would this me a neat little mod to do to the amp? just wondering if I do this to bring down the noise floor of the amp when not plugged in. It is WHISPER quiet with a guitar plugged in!!! very cool in that regard!

[gktamps]

I just had a Switchcraft shorting jack that was apparently not only incorrectly adjusted to short properly, but would not stay in adjustment. The contact springs have almost no memory, so just keep bending.