Sovtek mig 100 more low end please? too bright

[chris ogard]

Hello,
I just picked up a sovtek mig 100.
And although it sounds very good.
it is very bright.
I clipped the bright cap at the low input and although it did get me in the direction i want.
it was a subtle change .
and I still have the bass on 10 and mid , presence and treble at 3 or so.
Also i am not sure clipping the bright cap is really the best way to coax some low end out of it..
I have tried a couple different cabinets and still not quite enough low end.


My amp is the mig 100 but i believe it is the same as the mig 100u.
They also did a mig 100h that i know has some different resistor and capacitor values.

Thank you in advance any help appreciated

 

[FleshOnGear]

That amp should have plenty of guts. It’s very similar to a Marshall 2203. The Sovtek doesn’t have the cold biased 2nd stage, so not quite the same. Some say the 2203 is bright, but few say it’s excessively bright and lacking bass. Have you tried replacing the preamp tubes?

I have owned two Sovtek MIG100h amps, and both were plenty bassy. BTW the 100h is wired differently. The cathode follower stage of the 100 is replaced by another gain stage in the 100h.

 

[chris ogard]

Thanks for the reply.

Yes i have tried different combinations of preamp tubes.
i had a 50 watt jcm 800 years ago and i dont remember it being this bright
I also had a mig 50 h and it was not this bright

I am also using the low input btw.

here is something i found on the net ( differences in the mig 100 vs 100h
"Tube V3 (Phase splitter)
Mig 100(H) Ca V3.1/ V3.2 = .1uF (more bass)
Mig 100(H) Cg1 V3.1 = .01uF

Mig 100U Ca V3.1/ V3.2 = .022uF (less bass)
Mig 100U Cg1 V3.1 = .022uF"

 

[FleshOnGear]

First, I apologize for not properly welcoming you to the forum. Glad you’re here!

Yeah, the coupling caps between the PI and output grids are different. On the 100 the 0.022 caps with the 150k bias feed resistors gives -3dB knee at 48Hz. On the 100h, the 0.1 caps with the 150k bias feed resistors gives -3dB knee at 11Hz.

Both knees are below the bass notes of the guitar. The difference is probably a matter of subtle increase in cabinet thump on palm muted passages. Personally, I don’t believe increasing that capacitor will cure the brightness problem. I’m wondering if there is another issue with the amp.

Just out of curiosity, where do you have the Master set when you’re playing the amp?

 

[chris ogard]

Thanks for the welcome. Glad to be here!

I should mention i use the low input for a clean tone and a big muff for dirt

I have tried different combinations with the controls

i have the volume knob (preamp) on 6 and the using master to adjust overall level
that seems to have a bit more low end than the master maxed and the volume knob (preamp) to adjust overall level



I dont think there is a problem with the amp.. i guess there could be..
but is sounds good .
its quiet. no hum even with p90s
No weird sounds
it is responsive.
the big muff sounds fantastic through it

 

[66 Kicks]

Probably not causing your problem, but the Presence is not completely off when the knob is on zero.

It seems like every Sovtek amplifier was different and none of them were exactly like the schematic. (Nice schematic you posted, BTW. Where did you get that?) You might want to check the actual components in yours.

Here is a schematic for an actual 100 U.

 

[chris ogard]

Probably not causing your problem, but the Presence is not completely off when the knob is on zero.

It seems like every Sovtek amplifier was different and none of them were exactly like the schematic. (Nice schematic you posted, BTW. Where did you get that?) You might want to check the actual components in yours.

Here is a schematic for an actual 100 U.
View attachment 94601

 

[chris ogard]

i got the schematic on music electronics forum
I guess they made 3 different ones .
a 100 a 100u and a 100h
mine is the 100

 

[chris ogard]

From what i see ....
What my amp has that the U and H do not is an 82k resistor off the bass pot going to ground.

 

[66 Kicks]

i got the schematic on music electronics forum
I guess they made 3 different ones .
a 100 a 100u and a 100h
mine is the 100

I don't see it in their library. I know I posted that schematic somewhere, but I can't remember where. Was it in a post at music electronics forum?

 

[66 Kicks]

From what i see ....
What my amp has that the U and H do not is an 82k resistor off the bass pot going to ground.

From the wiper to ground?

 

[chris ogard]

Let me get a pic one minute

 

[chris ogard]

The bass pot is the 1m on the right .
the 25k is mid

 

[chris ogard]

I don't see it in their library. I know I posted that schematic somewhere, but I can't remember where. Was it in a post at music electronics forum?

yes on music electronics forum

 

[66 Kicks]

The 82K is going from the bass pot wiper to the treble pot wiper most likely. The tie point is insulated from the chassis.

 

[chris ogard]

The 82K is going from the bass pot wiper to the treble pot wiper most likely. The tie point is insulated from the chassis.

AHHH i just saw that lug and assumed it was to ground .but your right it is insulated

 

[chris ogard]

bump..anyone?

 

[FleshOnGear]

One more question for you. Do the EQ controls work well? I mean do they sound like they’re effective? Or do they sound like they’re not doing a whole lot?

 

[chris ogard]

One more question for you. Do the EQ controls work well? I mean do they sound like they’re effective? Or do they sound like they’re not doing a whole lot?

they definitely work.

 

[tschrama]

more bass: fix'ed depth mod: 4n7-1Meg in series with the FB resistor.
Tame the brightnes: 100pF from CF Cathode to Gnd