sunn 200s looping each imput

[vegedge]

so the 200s has 2 imputs. i have been told that when plugged into one, the other is bypassed. not true. i plugged to instruments in and both ran.

so i was wondering if any one else plays like this.
effects pedal(sansamp) into imput one, and passive output of pedal back into imput 2. giving me effect, and the natural 200s sound at the same time? it sounds good to me i think. not sure how much it is noticable put i know people loop imputs on the 2000s, traynors and bassman alot.

is this okay for the amp?
your thoughts?

[EdBass]

This is the schematic for the inputs on a 200S;



As you can see they are both the same and both go to the same place, for all intents and purposes they are just two jacks on a single input, and in fact the 200S is a single channel amp. It sounds like you are using this feature to blend wet and dry signals, which should be dandy.

Often players jumper channels on amps to add gain, but that isn't the case with old Sunns since they are single channel amps.

[vegedge]

its weird. the second channel is muffled and really feels like half the volume of the first imput. my friends 200s is the same way.

[Isaac]

To repeat, there is no second channel. The 200S is a single channel amp. If the second input is muffled, I suggest that the input jack is oxidized.

[EdBass]

Possibly one/both of the 68K resistors has drifted over the decades?

[loudthud]

When you plug something into the second input like a stomp box, signals from the first input will be attenuated by 6 dB or so. Also, the 200S has a lowish input impedance, around 200K. That tends to reduce the overall output of passive guitars.

[Isaac]

When you plug something into the second input like a stomp box, signals from the first input will be attenuated by 6 dB or so. Also, the 200S has a lowish input impedance, around 200K. Thata tends to reduce the overall output of passive guitars.

That seems unlikely. The 200S has a 68K input resistor, followed by a 1M to ground in parallel with the grid. For the 200S to have an input impedance of 200K, the grid resistance would have to be around 150K. As the 200S uses the same preamp tube as most other tube amps, they would all have a similarly low input impedance.

[Isaac]

Possibly one/both of the 68K resistors has drifted over the decades?

That's possible, but it would have to have drifted a lot to make a big difference.

[loudthud]

When you plug something into the second input like a stomp box, signals from the first input will be attenuated by 6 dB or so. Also, the 200S has a lowish input impedance, around 200K. Thata tends to reduce the overall output of passive guitars.

That seems unlikely. The 200S has a 68K input resistor, followed by a 1M to ground in parallel with the grid. For the 200S to have an input impedance of 200K, the grid resistance would have to be around 150K. As the 200S uses the same preamp tube as most other tube amps, they would all have a similarly low input impedance.

Sorry, I was thinking of the four input amps like the 100S and 2000S. The 200S does have the 1 Megohm input.

[Isaac]

That's cool. I didn't know that about the 2000S. I had always assumed that it had the same preamp as the 200S, but twice the power. Turns out I was quite wrong about that.

[D.M.N.]

I use both inputs on my 200s. I plug one output from my bass (the dagstar pickup) into input 1, and the output of the Jazz bass bridge pickup into input 2. Sometimes I also run effects off the Bridge pickup into input 2. I thought the inputs were supposed to be the same, as I have been told and has been discussed here. However, after playing around with them, I have to agree wit vegedge. I've definitely noticed a difference between input 1 & 2. Compared to input 1, #2 seems to be a bit quieter and less bassy. Switching back and forth between the inputs, same pickup, all settings the same (in my case, both switches engaged, treble at 10, bass at 10, vol at 2), the difference between the two is instantly recognizable. So not really sure what's going on there if that schematic of the inputs is accurate.

[Isaac]

The schematic accurately represents the inputs on my 200S. I'm inclined to think that the difference is corrosion on the Input 2 jack.

[D.M.N.]

I'd just be rather amazed that corrosion would have that much of an effect. It's quite noticable. My 200s is in pretty clean condition, so again it'd be interesting if input 2 had corroded that much compared to inout 1 less than half an inch away. If I have time today, maybe I'll pop mine open and take a look to compare it to the schematics.

[Isaac]

It would not surprise me, particularly if input 1 it used consistently, keeping its contacts clean, while input 2 sits idle while oxides slowly build up. Otherwise, I have to believe that two identical inputs have significantly different electrical characteristics for some other reason. Possible, but what might those reasons be?