Boosting SC200+ Mark IV

20 Studio, 50+, 50PA, 50R, L100, B100, L120, L120PA, L120R, 120 SLAVE, B120, B150, L150, L200, B200, Concord, and SMF

Boosting SC200+ Mark IV

Postby Vucinic on Tue May 17, 2016 2:56 pm

Hi,

Can someone recommend some power booster pedal to achieve natural overdrive considering active preamp on Mark IV

Thanks in advance

Bozo
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Re: Boosting SC200+ Mark IV

Postby partsstan on Tue May 17, 2016 4:28 pm

Hi; I like the Radial Tone Bone Hot British. It has a lot of adjustment and it is tube driven so you can try different tubes to customize your sound. :jam: :jam: :jam: :D
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Re: Boosting SC200+ Mark IV

Postby Vucinic on Wed May 18, 2016 7:09 am

I'm not a expert. so can you please advice?
My SC200+ have 4XECC83 and driver ECC81 in active preamp.
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Re: Boosting SC200+ Mark IV

Postby Papa Dog on Wed May 18, 2016 3:00 pm

Vucinic wrote:I'm not a expert. so can you please advice?
My SC200+ have 4XECC83 and driver ECC81 in active preamp.

that is correct

should have 4xECC83 (12AX7) and 1xECC81 (12AT7) as a Phase Inverter.

1 is the dual pre-amp
2 are the three tone sections and the "sensitivity" (gain).
last '83 is a driver and cathode follower.
that tube also has the "presence" control, which is really just a passive tone circuit with a very specific freq range, somewhere between the mids and the treble.

there are some "interesting" things about the Mk 4 circuit, especially as the pertain to both the 200+ and the 120+.
the pre-amp has a 200k plate resistor to each section.
this allows for very high "gain"
there is a 2k2 resistor in the cathode (both sections). This affords a fairly "center" bias.
So you can get a very "loud" output with very low distortion.
the "grid leak" on those amps is typically 220k. That means that with most guitars cranked up full, the amp is NOT supposed to "break up". Very hot pickups and big strings will give it some "edge" but not like an old plexi marshall.
The simplest "fix" for that is to raise the "grid leak" to 1M or 1M5, depending on taste. YMMV

the Mk 4 is "pedal friendly" in its natural state, but the deal is that if you put a distortion, fuzz, or overdrive ahead of that amp, then what you will most likely here is NOT the amp being pushed into overdrive, per se, but the sound of the box. The exception would be something like the "Dallas Range Master" type box, which boosts the signal in such a way as to overdrive the inputs on that amp. Really, a simple "clean boost" (and the simpler the better) placed directly ahead of the input will "do the trick" but the key is to add just enough to get what you want and still be able to "back off" and get the massive clean headroom these amps allow.

hope that helps
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Re: Boosting SC200+ Mark IV

Postby Vucinic on Fri May 20, 2016 11:01 am

Hi partsstan,

Because I cant force my amp to natural OD (maybe outside), I must do it with pedal. I check Radial Tone Bone Hot British. there is great review on you tube and I realy like it.
Thanks
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Re: Boosting SC200+ Mark IV

Postby partsstan on Tue May 24, 2016 4:19 am

Glad to be of help :cheers:
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Re: Boosting SC200+ Mark IV

Postby Mr. Foxen on Wed May 25, 2016 5:11 pm

200w is a lot of iron to be carrying about is breakup is what you are after.
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