FDP Forum / input jumper vs Y cord on SF Bassman100: any difference?/ 5 messages in thread.

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montana63



socialism

May 14th, 2017 04:41 PM        

I hooked up an A/B/Y pedal to my SFBM100 to compare the channels and happy surprise! the amp sounds EVEN MORE AWESOME(and loud AF!) than usual if I simply keep both channels on and use the volume knob for each channel to mix them, both on simultaneously. it occurred to me that I often use "input 2" to connect to another amp, IOW the inputs are parallel in/out, so I should get the same result if I just put a short patch cord between "input 2" of the "bass instrument" channel and "input 1" of the "NORMAL" channel... will this work exactly like running a Y cord or A/B/Y pedal to plug in to both channels at once? this is assuming I want both channels on and not needing to switch between them. hope my question makes sense...



pdf64



UK

May 15th, 2017 07:22 AM        

The channel inputs aren't directly in parallel, rather there are mixing resistors between them, probably to mitigate interaction between the inputs.<br /> Those resistors (68k) will tend to lose a bit of signal, most significantly high frequency roll off will be exacerbated.<br /> So use of a Y splitter should be better in that regard.



RDR

Contributing Member
********

I tried to think

but nothing happened!
May 18th, 2017 08:24 PM        

Let me ask this- if using a passive a/b/y switcher to input into both channels, is the signal strength into each input halved?



pdf64



UK

May 19th, 2017 05:39 AM        

No.<br /> In the Y mode, the 2 parallel inputs will load the instrument's PUs a tiny bit more than 1 input, but assuming use of the regular loud #1 input of a regular guitar amp, the effect on signal strength will be minuscule.<br /> If one or both of the inputs is a medium impedance eg line type, then the loading effect will be much greater, and signal strength may well drop 6dB.



montana63



Spokane

May 19th, 2017 12:56 PM        

I know this is subject to all sorts of psycho-acoustic cognitive dissonance on my part, but plugging in to this amp this way makes it "sound" twice as loud. when I start turning the volume up on both channels at once it feels like I am actually hearing both channels coming up in volume. in any case, the amp has more volume, headroom, depth of tone, clarity.. just overall sounds better and is really easy to dial in a little more of whatever part of my tone or overdrive I want at any volume. I'm actually using the stereo outputs on my TC Trinity Reverb to split into both channels now. sounds awesome.



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