The Amp Challenge Thread

[Hemisaurus]

aw heck paw, can'r we just use 10uF all round

[dunwichamps]

aw heck paw, can'r we just use 10uF all round

use large grid stoppers, >100k

[BrianDamage]

Ok I am completely retarded when it comes to this stuff so can anyone get a pic of which caps to clip to make my vtm 60 less ice picky or explain to me how to find them? Also do these caps need discharged before clipping or is that just the filter caps on the power board?

[Hemisaurus]

No those particular caps won't have much of a charge, nor will your filter caps if your amp isn't broken. The cap leads are the red dots on this layout diagram.



Unplug your amp, turn it on, let is sit for a minute.

[Chovie D]

"Unplug your amp, turn it on, let is sit for a minute."

I guess Im paranoid. I like to actually discharge the caps to be sure.

[dunwichamps]

you can always measure with a meter and make a discharge stick. Given this particular problem with working on amp i always use some damn bleeders and I wish every amp company did 2

[Hemisaurus]

"Unplug your amp, turn it on, let is sit for a minute."

I guess Im paranoid. I like to actually discharge the caps to be sure.

If the amp is working, turn it on without it plugged in does the same thing. If you're working around the HV you can always make sure with a meter, if you are snipping a cap from the top-side, I wouldn't worry.

But I guess he did say he was completely retarded, in which case my advice is Take it to a tech!

[BrianDamage]

I would take it to a tech but I am broke and if it is just clipping the caps I am comfortable doing that. Just needed help knowing which caps for sure because I would really not want to clip the wrong thing and have my amp get all shitty sounding.

[Hemisaurus]

Well clip the wrong caps, it may not sound atall. Maybe if Justin does it he'll take pics, I don't have one here to take pics of, we're working from schematics. You may find the board itself is labelled. It's the board the 12AX7's sit on. I suppose if you take pics of it, good pics, we can highlight the parts we're talking about.

Hopefully it is labelled and all you need to do is find the ones labelled C4 and C9 using the diagram as a road map.

[SpaceTrucker]

so, I got these dip switches on my vtm120. and their a pain in the ass you need a paper clip to move them. and some are starting to break. I would like to just drill and add a bunch of switches(metal flip switches). would I even be able to do this?

[Hemisaurus]

They are all SPST switches (one switch element one pole, they ever connect or don't) if you can physically find the panel space for them I don't see why not. 5 of them are for grounding parts of the circuitry, and another couple are hooked together, so you have 8 in but only 3 out, which might make wiring them a little easier, you'll have eight connections in, and 3 out.

Finding the panel space may be tricky, as the board that all the other controls are mounted on will get in the way.

It's easy enough to figure out what switches what, you have two rows of eight pins, the switch connects pin 1 of row 1 with pin 1 of row 2, and so it goes on all the way along.

If you only ever tweak some of the switches you could always just run a hardwire where the ones you leave on are, and no connection between the ones you always leave off, and just add switches for the ones you actually use.

[BrianDamage]

Ok I clipped those caps. Sounds much better. Kind of a half Marshall/half Orange tone. And now that I have done it can you explain to me what the caps were I got rid of and what it was they did to make it so trebley?

[dunwichamps]

Ok I clipped those caps. Sounds much better. Kind of a half Marshall/half Orange tone. And now that I have done it can you explain to me what the caps were I got rid of and what it was they did to make it so trebley?

There are resistive dividers which are used to knock the amplitude of your signal down before each gain stage. If there is just a resistive divider is affects all frequencies equally. If you add a bypass cap effectively what happens is that frequency's above a certain cutoff will pass through the resistive divider without being attenuated where as frequencies below the cutoff are normally attenuated. Thus you get a much brighter tone 

[Hemisaurus]

The caps bleed treble through

[dunwichamps]

The caps bleed treble through

sorry about my complicated explanation

[justinhedrick]

Ok I clipped those caps. Sounds much better. Kind of a half Marshall/half Orange tone. And now that I have done it can you explain to me what the caps were I got rid of and what it was they did to make it so trebley?

brian, did you clip both of them? i should do that to my VTM . . .

[VOLVO)))]

Y'ALL FIND OUT HOW TO CLIP THIS CAP OFF MY 800'S BOARD WITHOUT ME HAVING TO TAKE THE ENTIRE FUCKING THING OUT!

Bright cap, kill it with fire~

[Hemisaurus]

I was too simplistic, I should have addd the word deliberately.

Sunn that is a freak of a Marshall, I'm having nothing to do with it

You talking about C5 on that schematic? I don't know where they'd put it on yours, you can surely get at the component side of the PCB, no?

[VOLVO)))]

If it's really just clipping C5, I should just pop all the knobs and jacks, and just do it. Anything else interesting I should do to it?

[Hemisaurus]

Why not just clip one side of it close to the board first, if you like the sound, then dismantle it, if you don't, dismantle it, and solder the cap, back in.

Then again, why do I bother you always do the over complicated thing.

[VOLVO)))]

There isn't enough lead on that son of a bitch to clip. It's ceramic, if it were that easy, I would've done it. What's the value on it? I don't have the schem or layout handy at the moment... I should dig up a replacement before I snip anything out of it.

[Hemisaurus]

err, skip back a page

[VOLVO)))]

err, skip back a page

Zoinkas, got it!

[BrianDamage]

Ok I clipped those caps. Sounds much better. Kind of a half Marshall/half Orange tone. And now that I have done it can you explain to me what the caps were I got rid of and what it was they did to make it so trebley?

brian, did you clip both of them? i should do that to my VTM . . .

Yes I clipped them both. A much warmer amp now.

[dunwichamps]

gratz sounds good. Sometimes thats all it takes