sovtek mig 100u need to add some gain

dxjxrose · Post by **dxjxrose** » Sat Apr 28, 2012 2:11 am

cant find a schem for the 100u and need some advice about getting some more gain out of this amp

bluesbreaking · Post by **bluesbreaking** » Sat Apr 28, 2012 9:09 am

Why not just run a boost pedal into the front?

If it really needs to be in the amp, you could add a preamp tube. This was somewhere else on this site, but I posted it here for convenience's sake.

dxjxrose · Post by **dxjxrose** » Sat Apr 28, 2012 12:47 pm

not really looking into adding another tube more just resistor and cap tweaks

dxjxrose · Post by **dxjxrose** » Sun Apr 29, 2012 10:55 pm

anyone

bluesbreaking · Post by **bluesbreaking** » Mon Apr 30, 2012 1:57 pm

Is there a reason it has to be the amp? I guess I don't see why you don't just run a boost pedal into the amp?

dxjxrose · Post by **dxjxrose** » Mon Apr 30, 2012 2:04 pm

i do run a boost but i still need a touch more gain on tap for some heavier stuff my new band is playing

jerrydyer · Post by **jerrydyer** » Mon Apr 30, 2012 6:03 pm

what have you done so far? Put a 2700pf over the gain pot. Is it 2203 like.

dxjxrose · Post by **dxjxrose** » Mon Apr 30, 2012 7:39 pm

yes it is just a touch les gain

Jingletone · Post by **Jingletone** » Wed May 02, 2012 11:42 am

If you post a picture of the board i will tell you exactly what you need to do. Probably a 1uf cap on the cathode resistor of the second gain stage will do it. But.. If you want to make it a fire breathing gain machine you can, you just need to change most of the caps and resistors on the the first two stages of gain.. How much experience do you have working on electronics? Do you know how not to shock youself? You can get these amps very high gain with a little work, without adding another tube.

dxjxrose · Post by **dxjxrose** » Wed May 02, 2012 11:52 am

and yes i have worked on amps and know to drain the caps. i have taken a class on electronics yrs ago but just have some issues knowing what each part does in a tube amp.

Jingletone · Post by **Jingletone** » Wed May 02, 2012 11:53 am

Here is the scematic, higher gain than i expected... But probably kinda honky due to the. 047 coupling cap.
[url][http://www.clintronics.com/images/Sovte ... ic.jpg/url]

dxjxrose · Post by **dxjxrose** » Wed May 02, 2012 12:00 pm

the 100 is more like a jcm800 the 100u is like a plexi and the 100h is hot rodded 800

Jingletone · Post by **Jingletone** » Wed May 02, 2012 12:05 pm

On he first gain stage, i would change the 100k plate resistor to a 220k with a 470pf disc bypassing it. This will lower the plate voltage from abour 250v to about 170v. This might be all you have to do, it will lower the clipping point of the tube and sound good. If you want to go bigger change the .47 bypass cap on the first stage to a 1uf capacitor. This will make for a smoother let honky gain. But you will probably then want to change the coupling cap from .047 to .022 or even .010 to filter out some of the low lows the 1uf will add. Then... I would change the 22uf cathode bypass on the second stage to a 1uf or a .068uf cap. It will make the amp tighter and just sound better in my opinion. Also i would concider a resonance mod on this amp. Ive added them to similiar circuits and they sounded great!

Jingletone · Post by **Jingletone** » Wed May 02, 2012 12:06 pm

dxjxrose wrote:the 100 is more like a jcm800 the 100u is like a plexi and the 100h is hot rodded 800

Wow i didnt know they made so many versions. Let me look a little closer and ill get back to you in a bit.
So if yours is a 100u and is like a plexi, does it have a master volume?

If yours is a non master volume its probably the same as this one.
http://www.blueguitar.org/new/schem/sovtek/mig-50.pdf

dxjxrose · Post by **dxjxrose** » Wed May 02, 2012 12:23 pm

and i already did a depth or resonance control on it helped alot but what i am after is a more zakk wylde/ randy rhodes kinda sound...

also i am not well enough versed with tube amps to know exactly which part to change via your last post alil more guidance would be greatly appreciated

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sovtek mig 100u need to add some gain

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