How Many Mods are out there?

[malachais]

Hi All.
was wondering what mods were availible?
seen the gain boost on here.
does it work on all channels? or just one?

id love to see what was availible for a AVT150HX

thanks
Malachais

[fixr1984]

The gain boost works with both channels. It boosts the pre amp gain so thankfully it will work with either channel.

As far as i know there hasn't been any mods for the AVT150 as of yet. I'm sure the gain boost option would work but not having seen a schematic for it I have no clue where to start.

[Marshall]

Doesn't the AVT150 already have that boost option?

If I remember correctly it has Clean/Crunch OD OD2.

Maybe the tone mod Fixr suggested at the Marshall Forum would help you out.

[fixr1984]

I would be more than happy to show pics and a little write up on the mid shift mod for the AVT50 if anyone in interested. It could most likely be added to the AVT150

[malachais]

Hi there guys.

Fixr1984, id love to see the mid shift.
also, Marshall, the AVT150 has Acc. Sim, Clean, OD1 and OD2

maybe in a week or two (if i try the gain boost) ill take pics for the guts of the avt150H and post em.

also, am i completely stupid for asking of the possibility of adding a second tube? the AVT150H only has one.

would that work? or just be dumb with the tube/transistor mix?

thanks
all the best Malachais

[Marshall]

MM.. now we are talking, adding another tube would be fun. The Mode Four has a couple of preamp tubes in them but I think they have 2 amps built into one. Maybe a mod could be done to switch tubes on and off with out having to manually do it?

[Marshall]

The way to do it would be with a Preamp tube for each channel. So the AVT 150 could run 4 for the (Acoustic/Clean/OD/OD2) and the AVT could run 2 (Clean/OD). It might be impossible though, I would really need a good look at the design. What do you think Fixr?

[fixr1984]

I think the idea is good but I would guess major modifications to make it work. Something to think about.

[fixr1984]

I will be getting a large stash of tubes this weekend. I have no clue what #'s they are or if they are usable, I have a few ideas floating around that I will share once I recieve them.

[Marshall]

Cool, keep us posted.

[malachais]

ya forsure.

pm me when you have some ideas.

might buy a second head locally as backup

cheers

[fixr1984]

The guy i'm getting them from works in a mill that just closed down, they have boxes and boxes of NOS tubes they are going to toss out. I told him that I would take everything they had but he insists that he check them all over and get me only the numbers I ask for. I looked everywhere I could and gave him a huge list.

So far all I have gotten is about 10 12au7 nationals and 5 5751 (1 GE and 4 national). He is still looking, he has to cross the number on the box over to the standard number and its taking him a while. (he should have just given them all to me...lol)

My ideas are to possibly add a footswitchable? tube as a gain boost. Maybe try to make it so each channel has its own tube. Run more than one pre amp tube. or add a tube driven tremelo. Lots of possibilities.

[malachais]

i got a 9 page schematic for the avt150h.
here is the link

www.wilderamplification.com/schematics/Marshall/avt150h.pdf

here is the root directory of (not my work obviously) the guys schematics if anyone wants.

www.wilderamplification.com/schematics/

so... im learning... but a jcm series has pre amp and power amp tubes? is that right?
and the avt has a preamp tube, and solid state power amp?

also.... is there any difference between the avt150h and the avt 150hx?
ive read that its just a newer relaese??

thanks guys

[malachais]

hey fixr.... hope all is well.

you think your "gain mod" would work on my sweety? (avt150HX)

thanks
Malachais

[fixr1984]

For some reason most of the posts this last month just started showing up for me...Yes it should work. Check your PM