Hello, JahNice
thanks a lot for checking it out and replying
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As for "sound before (or after) modification", there is no really difference in terms of how the mixer or reverb/mix "sounds", as I have not change anything in the audio path.
I've just added control and inputs. So it's the same mixer but with more features
The potentiometers on each channel that I've added only provide control over how much signal you want to send to reverb from each individual channel. Before that, all you could do was to turn reverb ON or turn OFF ("send to reverb" that is) on the chanel by flipping the switch (so it's like having send-to-effect button (aux send) but no "send knob" on a mixer).
And another modification was to add Line-Level inputs. Before you only have mic level input, which means that the signal goes through a mic preamplifier, and if you plug a line-level signal into it - you get too high signal level and it gets overloaded and distorted.
So the line level inputs are there "bypassing" the mic preamp stage and go right to channel's level (volume) control (the fader) and then to chanel amp stage and then to Bass/Treble passive eq (tone control).
So this second mod is kind of important if you want to use this unit as spring reverb effect when dubbing (where you send line-level signal from your dubbing mixer to Spring Reverb unit). And the coolest part of MPR-6 is that it is a spring reverb, but you can send up to six different parts (instruments, tracks, channels) while dubbing, and have a lots of control over the situation and dub on the fly LIKE YOU MEAN IT
Also, nice thing about this unit is that it can be used simply as spring reverb effect or as mic mixer, this would be appreciated by dubbers who record acoustic instruments, drums and what ever with microphones.
Also at the same time it is a siple yet pretty good preamp with reverb for a guitar player. You can simply plug electric guitar into mic input and record your guitar to what ever recorder or computer from the output of MPR-6 and you can add spring reverb to guitar while recording, which is always cool thing.
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So for all these reasons I've decided to take time to do all this detailed work to demonstrate what this unit is about.
Just wanted to share this with Dub-Men
I've seen these mixers out on eBay, not often though, but sometimes, and they sell rather cheap, maybe most people don't see them as much useful or something.
I think there are also some older TAPCO mixers with spring reverb in it which may be similar, but I don't know for sure (and couple or few others).
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God Bless
and keep on Dubbin'